Thèses : « CO2 capture and conversion »

1

Brandvoll, Øyvind. « Chemical looping combustion : fuel conversion with inherent CO2 capture ». Doctoral thesis, Norwegian University of Science and Technology, Department of Energy and Process Engineering, 2005. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-1203.

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Chemical looping combustion (CLC) is a new concept for fuel energy conversion with CO₂ capture. In CLC, fuel combustion is split into seperate reduction and oxidation processes, in which a solid carrier is reduced and oxidized, respectively. The carrier is continuously recirculated between the two vessels, and hence direct contact between air and suel is avoided. As a result, a stoichiometric amount of oxygen is transferred to the fuel by a regenerable solid intermediate, and CLC is thus a varient of oxy-fuel combustion. In principle, pure CO₂ can be obtained from the reduction exhaust by condensation of the produced water vapor. The termodynamic potential and feasibility of CLC has been studied by means of process simulatons and experimental studies of oxygen carriers. Process simulations have focused on parameter sensitivity studies of CLC implemented in 3 power cycles; CLC-Combined Cycle, CLC-Humid Air Turbine and CLC-Integrated Steam Generation. Simulations indicate that overall fuel conversion ratio, oxidation temperature and operating pressure are among the most imortant process parameters in CLC. A promising thermodynamic potentail of CLC has been found, with efficiencies comparable to, - or better than existing technologies for CO₂capture. The proposed oxygen carrier nickel oxide on nickel spinel (NiONiA1) has been studied in reduction with hydrogen, methane and methane/steam as well as oxidation with dry air. It has been found that at atmosphereic pressure and temperatures above 600° C, solid reduction with dry methane occurs with overall fuel conversion of 92%. Steam methane reforming is observed along with methane cracking as side reactions, yealding an overall selectivity of 90% with regard to solid reduction. If steam is added to the reactant fuel, coking can be avoided. A methodology for long term investigation of solid chemical activity in a batch reactor is proposed. The method is based on time variables for oxidaton. The results for NiONiA1 do not rule out CLC as a viable alternative for CO₂capture, but long term durability studies along with realistic testing of the carrier in a continuous rig is needed to firmly conclude. For comparative purposes a perovskite was synthesized and tested in CLC, under similar conditions as NiONiA1. The results indicate that in a moving bed CLC application, perovskites have inherent disadvantages as compared to simpler compounds, by virtue of low relative oxygen content.

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Kim, Hyung Rae. « Chemical Looping Process for Direct Conversion of Solid Fuels In-Situ CO2 Capture ». The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1250605561.

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MARCHESE, MARCO. « Conversion of industrial CO2 to value-added fuels and chemicals via Fischer-Tropsch upgrade ». Doctoral thesis, Politecnico di Torino, 2021. http://hdl.handle.net/11583/2914540.

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Shokouhfar, Nasrin. « Synthèse et caractérisation de nouvelles armatures métal-organique à base de zirconium à partir de ligands carboxylates et étude de leur application dans l'adsorption et la détection des pollutions de l'eau et la capture et la conversion du CO2 et N2 ». Electronic Thesis or Diss., Université de Lille (2022-....), 2023. http://www.theses.fr/2023ULILN058.

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Cette thèse porte sur la synthèse et la caractérisation de cadres métallo-organiques (MOF) à base de Zr et leurs applications dans le traitement de l'eau et la production de carburant solaire. Les MOF sont des matériaux poreux composés d'ions métalliques et d'éléments de liaison organiques qui présentent des structures et des fonctionnalités ajustables. Ces propriétés les rendent aptes pour diverses applications, telles que le stockage de gaz, la catalyse, la détection, l'administration de médicaments, etc.Le traitement de l'eau consiste à éliminer les contaminants de l'eau afin de la rendre propre et sans danger pour l'homme. L'un des principaux contaminants de l'eau sont les colorants, largement utilisé dans les industries du textile, du papier et du cuir. La pollution par les colorants peut entraîner de graves problèmes pour la vie aquatique, la santé humaine et la qualité esthétique de l'eau. Pour éliminer les colorants de l'eau, nous avons synthétisé un nouveau Zr-MOF appelé TMU-66, qui a une forme de sphère creuse et un groupe fonctionnel N-oxyde. TMU-66 peut adsorber efficacement et sélectivement les molécules de colorant par le biais de diverses interactions, telles que les interactions électrostatiques, l'empilement π-π et la liaison de coordination. TMU-66 a présenté une capacité d'adsorption de 472 mg/g pour le colorant rouge Congo à un pH de 6,8 et à 25 °C, une des valeurs les plus élevées obtenues jusqu'à présent pour des adsorbants à base de MOF.La production de combustibles solaires est le processus de conversion de l'énergie solaire en combustibles chimiques qui peuvent être stockés et utilisés ultérieurement. L'un des carburants les plus prometteurs est l'ammoniac (NH3), qui peut être produit à partir d'azote (N2) et d'eau (H2O) en utilisant l'irradiation solaire comme source d'énergie. Ce processus est appelé photoréduction de N2 ou fixation photocatalytique de l'azote. Cependant, ce processus est difficile car N2 est très stable et difficile à décomposer. Nous avons modifié un autre Zr-MOF, appelé MOF-808, en introduisant un groupe nitro dans le linker organique. Cette structure modifiée peut absorber la lumière visible et transférer des électrons aux molécules de N2. Nous avons également combiné le MOF-808/NIP avec un autre matériau, le g-C3N4, pour améliorer l'absorption de la lumière et le transfert d'électrons. Le composite ainsi obtenue, MOF-808/NIP@g-C3N4, peut produire jusqu'à 490 μmol d'ammoniac par gramme de composite et par heure sous irradiation visible.En résumé, les objectifs de ce travail de thèse étaient d'étudier le potentiel des MOF pour deux applications distinctes, en utilisant une approche conceptuelle qui intègre l'ingénierie de la bande interdite, la modulation de la structure et les matériaux composites à hétérojonction. Les résultats ont révélé que les MOF peuvent adsorber les impuretés de l'eau et fonctionner comme des photocatalyseurs pour produire de l'ammoniac grâce à la photoréduction de N2 sous irradiation visible. Les résultats obtenus ouvrent des perspectives très intéressantes dans le domaine de traitement de l'eau polluée et de production d'ammoniac. Ces technologies sont cruciales pour sauvegarder notre planète et garantir un avenir stable
This thesis investigates the synthesis and characterization of Zr-based metal-organic frameworks (MOFs) and their applications in water treatment and solar fuel production. MOFs are porous materials composed of metal ions and organic linkers that exhibit tuneable structures and functionalities. These properties make them suitable for various applications, such as gas storage, catalysis, sensing, drug delivery, etc.Water treatment is the process of removing contaminants from water to make it safe and clean for human use. One of the main contaminants in water are dyes, which are widely used in the textile, paper, and leather industries. Dye pollution can cause serious problems for aquatic life, human health, and aesthetic quality of water. To remove dyes from water, we synthesized a new Zr-MOF called TMU-66, which has a hollow sphere shape and an N-oxide functional group. TMU-66 can efficiently and selectively adsorb dye molecules through various interactions, such as electrostatic attraction, π-π stacking, and coordination bonding. TMU-66 exhibited and adsorption capacity of 472 mg/g for Congo red dye at pH 6.8 and 25 °C, one of the highest values achieved for MOF-based adsorbents so far.Solar fuel production is the process of converting solar energy into chemical fuels that can be stored and used later. One of the most promising fuels is ammonia (NH3), which can be produced from nitrogen (N2) and water (H2O) using sunlight as the energy source. This process is called N2 photoreduction or photocatalytic nitrogen fixation. However, this process is challenging because N2 is very stable and difficult to break apart. We modified another Zr-MOF called MOF-808 by adding a nitro group to its linker. The modified framework is able to absorb visible light and transfer electrons to N2 molecules. We also combined MOF-808/NIP with another material called g-C3N4, which can enhance light absorption and electron transfer. The resulting composite, MOF-808/NIP@g-C3N4, can produce up to 490 μmol ammonia per gram of composite per hour under visible light and ambient conditions.In summary, the objectives of this thesis work were to investigate the potential of MOFs for two distinct applications, utilizing a conceptual design approach that incorporated bandgap engineering, structure modulation, and heterojunction composite materials. The findings revealed that MOFs can absorb water impurities and function as photocatalysts to achieve ammonia production through solar-powered N2 photoreduction. This breakthrough has the potential to foster the creation of more effective and environmentally conscious technologies that tackle worldwide water pollution and ammonia production issues. These technologies are crucial in safeguarding our planet and guaranteeing a stable future

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Ramkumar, Shwetha. « CALCIUM LOOPING PROCESSES FOR CARBON CAPTURE ». The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1274882053.

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Daza, Yolanda Andreina. « Closing a Synthetic Carbon Cycle : Carbon Dioxide Conversion to Carbon Monoxide for Liquid Fuels Synthesis ». Scholar Commons, 2016. http://scholarcommons.usf.edu/etd/6079.

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CO2 global emissions exceed 30 Giga tonnes (Gt) per year, and the high atmospheric concentrations are detrimental to the environment. In spite of efforts to decrease emissions by sequestration (carbon capture and storage) and repurposing (use in fine chemicals synthesis and oil extraction), more than 98% of CO2 generated is released to the atmosphere. With emissions expected to increase, transforming CO2 to chemicals of high demand could be an alternative to decrease its atmospheric concentration. Transportation fuels represent 26% of the global energy consumption, making it an ideal end product that could match the scale of CO2 generation. The long-term goal of the study is to transform CO2 to liquid fuels closing a synthetic carbon cycle. Synthetic fuels, such as diesel and gasoline, can be produced from syngas (a combination of CO and H2) by Fischer Tropsch synthesis or methanol synthesis, respectively. Methanol can be turned into gasoline by MTO technologies. Technologies to make renewable hydrogen are already in existence, but CO is almost exclusively generated from methane. Due to the high stability of the CO2 molecule, its transformation is very energy intensive. Therefore, the current challenge is developing technologies for the conversion of CO2 to CO with a low energy requirement. The work in this dissertation describes the development of a recyclable, isothermal, low-temperature process for the conversion of CO2 to CO with high selectivity, called Reverse Water Gas Shift Chemical Looping (RWGS-CL). In this process, H2 is used to generate oxygen vacancies in a metal oxide bed. These vacancies then can be re-filled by one O atom from CO2, producing CO. Perovskites (ABO3) were used as the oxide material due to their high oxygen mobility and stability. They were synthesized by the Pechini sol-gel synthesis, and characterized with X-ray diffraction and surface area measurements. Mass spectrometry was used to evaluate the reducibility and re-oxidation abilities of the materials with temperature-programmed reduction and oxidation experiments. Cycles of RWGS-CL were performed in a packed bed reactor to study CO production rates. Different metal compositions on the A and B site of the oxide were tested. In all the studies, La and Sr were used on the A site because their combination is known to enhance oxygen vacancies formation and CO2 adsorption on the perovskites. The RWGS-CL was first demonstrated in a non-isothermal process at 500 °C for the H2-reduction and 850 °C for the CO2 conversion on a Co-based perovskite. This perovskite was too unstable for the H2 treatment. Addition of Fe to the perovskite enhanced its stability, and allowed for an isothermal and recyclable process at 550 °C with high selectivity towards CO. In an effort to decrease the operating temperature, Cu was incorporated to the structure. It was found that Cu addition inhibited CO formation and formed very unstable oxide materials. Preliminary studies show that application of this technology has the potential to significantly reduce CO2 emissions from captured flue gases (i.e. from power plants) or from concentrated CO2 (adsorbed from the atmosphere), while generating a high value chemical. This technology also has possible applications in space explorations, especially in environments like Mars atmosphere, which has high concentrations of atmospheric carbon dioxide.

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Trompelt, Michael. « Untersuchung von Möglichkeiten zur Wirkungsgradsteigerung von braunkohlegefeuerten IGCC-Kraftwerken mit CO2-Abtrennung ». Doctoral thesis, Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2015. http://nbn-resolving.de/urn:nbn:de:bsz:105-qucosa-158214.

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Mit der Arbeit werden braunkohlegefeuerte IGCC-CCS-Kraftwerke gesamtheitlich beschrieben, deren Potenziale erarbeitet und mit ASPEN Plus™ sowie EBSILON® Professional simulativ abgebildet. Es kann gezeigt werden, dass ausgehend von Basiskonzepten braunkohlegefeuerter IGCC-CCS-Kraftwerke mit verschiedenen Potenzialen zum gegenwärtigen Stand der Technik sowie dem im Jahr 2025 Wirkungsgradsteigerungen sowie prozesstechnische Vereinfachungen möglich sind. Als Potenziale werden dabei verringerte Braunkohletrocknung, konservativere Annahmen der technologischen Auslegung als auch Modifizierungen der CO-Konvertierung, sowie für das Jahr 2025 konservative Annahmen und innovative Potenziale untersucht. Ausgangspunkt bildet eine Analyse von bestehenden und zukünftig erwarteten Prozesskomponenten braunkohlegefeuerter IGCC-CCS-Kraftwerke unter Berücksichtigung von drei unterschiedlichen Vergasungsverfahren (nach Siemens, nach Shell und dem HTW-Verfahren).

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Danaci, Simge. « Optimisation et intégration de catalyseurs structurés en réacteurs structurés pour la conversion de CO₂ en méthane ». Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAI041/document.

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Dans cette étude de doctorat, la technique de dépôt tridimensionnel de fibres (3DFD) a été appliquée pour développer et fabriquer des structures de support catalytique multi-canaux avancées. En utilisant cette technique, le matériau, la porosité, la forme et la taille des canaux et l'épaisseur des fibres peuvent être contrôlées. L'objectif de cette recherche est d'étudier les performances des supports structurés 3D conçus pour la méthanation du CO2 en termes d'activité, de sélectivité de stabilité et d’étudier l'impact des propriétés spécifiques introduites dans la conception structurale des supports
In this doctoral study, the three dimensional fibre deposition (3DFD) technique has been applied to develop and manufacture advanced multi-channelled catalytic support structures. By using this technique, the material, the porosity, the shape and size of the channels and the thickness of the fibres can be controlled. The aim of this research is to investigate the possible benefits of 3D-designed structured supports for CO2 methanation in terms of activity, selectivity and stability and the impact of specific properties introduced in the structural design of the supports

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Zeng, Liang. « Multiscale Study of Chemical Looping Technology and Its Applications for Low Carbon Energy Conversions ». The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1354722135.

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Olivieri, Luca <1987&gt. « Polymeric membranes for CO2 capture ». Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amsdottorato.unibo.it/7418/4/olivieri_luca_tesi.pdf.

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The object of this PhD work is the study of innovative, composite and nanostructured polymeric materials for membrane-based separation and removal of CO2 from gaseous streams. The research on gas separation membranes, in the last two decades was largely devoted to the synthesis and fabrication of new, multiphasic materials, such as copolymers, composite materials bearing fillers dispersed in the polymeric matrix, or functionalized materials having selective functional groups attached to the polymer backbone. The materials investigated in this thesis can be divided in three classes: copolyetherimides: copolymers formed by a glassy polyimide phase, composite membranes, commonly defined as Mixed Matrix Membranes, functionalized materials obtained by chemically attaching amine moieties to a polymeric backbone for the instauration, in appropriate operative conditions, of the facilitated transport mechanism of CO2. All the above materials have the advantage that their transport properties, in terms of solubility, diffusivity and thus of gas permeability and selectivity, can be tuned and adjusted for the practical purpose. To this end, in this work, an experimental campaign devoted to the measurement of transport properties will be supported by a modeling approach on the continuous scale, for better understanding mass transport properties and the influence of material formulation on them, and develop easily accessible models for the prediction of materials behavior.

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Olivieri, Luca <1987&gt. « Polymeric membranes for CO2 capture ». Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amsdottorato.unibo.it/7418/.

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The object of this PhD work is the study of innovative, composite and nanostructured polymeric materials for membrane-based separation and removal of CO2 from gaseous streams. The research on gas separation membranes, in the last two decades was largely devoted to the synthesis and fabrication of new, multiphasic materials, such as copolymers, composite materials bearing fillers dispersed in the polymeric matrix, or functionalized materials having selective functional groups attached to the polymer backbone. The materials investigated in this thesis can be divided in three classes: copolyetherimides: copolymers formed by a glassy polyimide phase, composite membranes, commonly defined as Mixed Matrix Membranes, functionalized materials obtained by chemically attaching amine moieties to a polymeric backbone for the instauration, in appropriate operative conditions, of the facilitated transport mechanism of CO2. All the above materials have the advantage that their transport properties, in terms of solubility, diffusivity and thus of gas permeability and selectivity, can be tuned and adjusted for the practical purpose. To this end, in this work, an experimental campaign devoted to the measurement of transport properties will be supported by a modeling approach on the continuous scale, for better understanding mass transport properties and the influence of material formulation on them, and develop easily accessible models for the prediction of materials behavior.

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Xu, Shaojun. « Plasma-assisted conversion of CO2 ». Thesis, University of Manchester, 2017. https://www.research.manchester.ac.uk/portal/en/theses/plasmaassisted-conversion-of-co2(19c87dfa-ba79-47ea-a63d-0a0026a03bba).html.

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The transformation of carbon dioxide into added value chemicals by a plasma-activated catalytic process was studied. First of all, the current status of CO2 reutilisation by plasma-assisted technologies was reviewed. Followed by an in-depth study on the process of plasma-catalysis, the effects of dilution gas (i.e. argon and nitrogen) addition and operating parameters in CO2 dissociation were systematically investigated in non-thermal atmospheric pressure plasma barium titanate (BaTiO3) packed-bed reactor from both an engineering and scientific point of view. The extensive experimental and modelling study provided an insight into the relationship between the operating parameters, plasma electrical properties and electron-induced reaction processes in the discharge and the effect of the dilution gases on the product formation and reaction mechanism. The results showed that there was a higher CO2 conversion and energy efficiency in the studied packed-bed reactor than the dielectric barrier discharge (DBD) reactor with and without packed materials using electrodes covered by dielectric layers. Based on the above research work, an in-depth study of the complex mechanism of plasma-catalysis interface reaction was carried out. A new model catalyst (Ni/Î±-Al2O3 nanocatalyst) with a minimum of physical and chemical variables was specifically designed and synthesised for plasma-assisted reactions to help directly understand the intrinsic role of catalytic active sites during the plasma-catalytic process. In situ time-resolved tuneable lead salt diode laser (TDL) diagnostics of carbon dioxide decomposition over the model catalysts in a planar dielectric barrier discharge (DBD), non-thermal atmospheric pressure plasma reactor demonstrated that the active Ni metal sites do enhance the plasma-catalytic reaction in a similar way as that in conventional catalytic processes. Finally, demonstration of a novel catalysis concept of in situ capture-catalytic system was made for the plasma-assisted catalytic water gas shift reaction. This was investigated in a barium titanate (BaTiO3) packed-bed, non-thermal atmospheric pressure plasma reactor operating at 298 K. The results showed that the packed-bed reactor with CuBTC metal-organic framework (MOF) addition enhanced the CO conversion up to 43%. The comprehensive characterisation of the CuBTC MOF shows that CuBTC MOF exhibited sustainably good physical and chemical stabilities during 4 h long term continuous plasma reaction. The research work in this thesis showed that the BaTiO3 ferroelectric, packed-bed, non-thermal plasma reactor is a potential and powerful environmental solution for CO2 dissociation and other similar pollution treatments with a much higher conversion and energy efficiency at a high specific input energy, more mature and cheaper reactor configuration to scale-up without the need for dielectric barriers. As catalyst introduced into the plasma-assisted process, the demonstrated similar catalytic role of catalytic active sites in plasma-catalytic processes as in conventional thermal catalytic processes opened the gate to apply the catalysts and basic catalytic theories in conventional thermal catalysis field into the non-thermal and atmospheric plasma processes. The boundary of catalysis has been further extended, especially for the non-thermal atmospheric catalytic processes. The catalysis concept for the combination of plasma-catalytic process and conventional thermal catalytic process to enhance the adsorption process of the reactant and then catalyse it simultaneously over the active sites at room temperature and atmospheric pressure could be realised, as demonstrated by using the MOFs with a large gas capture capacity to catalyse water gas shift reaction in non-thermal atmospheric plasma.

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Dugstad, Tore, et Esben Tonning Jensen. « CO2 Capture from Coal fired Power Plants ». Thesis, Norwegian University of Science and Technology, Department of Energy and Process Engineering, 2008. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-9770.

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Coal is the most common fossil resource for power production worldwide and generates 40% of the worlds total electricity production. Even though coal is considered a pollutive resource, the great amounts and the increasing power demand leads to extensive use even in new developed power plants. To cover the world's future energy demand and at the same time limit our effect on global warming, coal fired power plants with CO2 capture is probably a necessity. An Integrated Gasification Combined Cycle (IGCC) Power Plant is a utilization of coal which gives incentives for CO2 capture. Coal is partially combusted in a reaction with steam and pure oxygen. The oxygen is produced in an air separation process and the steam is generated in the Power Island. Out of the gasifier comes a mixture of mainly H2 and CO. In a shift reactor the CO and additional steam are converted to CO2 and more H2. Carbon dioxide is separated from the hydrogen in a physical absorption process and compressed for storage. Hydrogen diluted with nitrogen from the air separation process is used as fuel in a combined cycle similar to NGCC. A complete IGCC Power Plant is described in this report. The air separation unit is modeled as a Linde two column process. Ambient air is compressed and cooled to dew point before it is separated into oxygen and nitrogen in a cryogenic distillation process. Out of the island oxygen is at a purity level of 95.6% and the nitrogen has a purity of 99.6%. The production cost of oxygen is 0.238 kWh per kilogram of oxygen delivered at 25°C and 1.4bar. The oxygen is then compressed to a gasification pressure of 42bar. In the gasification unit the oxygen together with steam is used to gasify the coal. On molar basis the coal composition is 73.5% C, 22.8% H2, 3.1% O2, 0.3% N2 and 0.3% S. The gasification temperature is at 1571°C and out of the unit comes syngas consisting of 66.9% CO, 31.1% H2, 1.4% H2O, 0.3% N2, 0.2% H2S and 0.1% CO2. The syngas is cooled and fed to a water gas shift reactor. Here the carbon monoxide is reacted with steam forming carbon dioxide and additional hydrogen. The gas composition of the gas out of the shift reactor is on dry basis 58.2% H2, 39.0% CO2, 2.4% CO, 0.2% N2 and 0.1% H2S. Both the gasification process and shift reactor is exothermal and there is no need of external heating. This leads to an exothermal heat loss, but parts of this heat is recovered. The gasifier has a Cold Gas Efficiency (CGE) of 84.0%. With a partial pressure of CO2 at 15.7 bar the carbon dioxide is easily removed by physical absorption. After separation the solvent is regenerated by expansion and CO2 is pressurized to 110bar to be stored. This process is not modeled, but for the scrubbing part an energy consumption of 0.08kWh per kilogram CO2 removed is assumed. For the compression of CO2, it is calculated with an energy consumption of 0.11kWh per kilogram CO2 removed. Removal of H2S and other pollutive unwanted substances is also removed in the CO2 scrubber. Between the CO2 removal and the combustion chamber is the H2 rich fuel gas is diluted with nitrogen from the air separation unit. This is done to increase the mass flow through the turbine. The amount of nitrogen available is decided by the amount of oxygen produced to the gasification process. Almost all the nitrogen produced may be utilized as diluter except from a few percent used in the coal feeding procedure to the gasifier. The diluted fuel gas has a composition of 50.4% H2, 46.1% N2, 2.1% CO and 1.4% CO2. In the Power Island a combined cycle with a gas turbine able to handle large H2 amounts is used. The use of steam in the gasifier and shift reactor are integrated in the heat recovery steam generator (HRSG) in the steam cycle. The heat removed from the syngas cooler is also recovered in the HRSG. The overall efficiency of the IGCC plant modeled is 36.8%. This includes oxygen and nitrogen production and compression, production of high pressure steam used in the Gasification Island, coal feeding costs, CO2 removal and compression and pressure losses through the processes. Other losses are not implemented and will probably reduce the efficiency.

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DeLucia, David Earl. « Cyclic use of limestone for CO2 capture ». Thesis, Massachusetts Institute of Technology, 1985. http://hdl.handle.net/1721.1/15136.

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Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1985.
MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING
Bibliography: leaf 150.
by David Earl DeLucia.
M.S.

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Higby, Joshua. « Conversion of CO2 to higher alcohols ». Thesis, Luleå tekniska universitet, Industriell miljö- och processteknik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-83392.

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I rapporten framgår det en termodynamisk analys för reverse water gas shift med att sammanmata etanol för att undvika det långsammaste steget i reaktionen för att producera högre alkoholer. Ifrån ett termodynamiskt perspektiv, verkar det möjligt att utgå ifrån reverse water gas shift för att producera högre alkoholer vid 100 bar med en temperatur på 300C . Reaktionen är exotermisk, vilket gynnas av det låga temperaturer och det rekommenderas höga tryck p.g.a. en mol kontraktion. Jämviktshalterna var låga, det föreslås att ta bort vatten ifrån jämvikten. I den matematiska modellen utgick det ifrån en kedja-reaktion för att producera högre alkoholer med reverse water gas shift i processförhållanden på 10–200 bar. I modellen utfördes en senstivty-analysis för jämvikten på tryck och vattenborttagning. Genom att ta bort vatten ifrån jämvikten låg CO2 utbytet kring 95% vid 200 bar även vid låga tryck som 10 bar. Inom CO2 hydrering till högre alkoholer är det begränsat med data och reaktionsmekanismen bakom reaktionen är inte riktigt förstådd. Experimentella försök krävs för att få en mer ökad förståelse. I modellen beskrevs CO2 hydrering och resterande reaktioner som en funktion av en sigmoid. Inom litteraturstudien kom det fram till att det fanns ingen kommersiell tillgänglig membran förtillfället för att ta bort vatten inom krävande process förhållanden. Tekniken ser dock lovande ut.
In this work, a thermodynamic analysis for CO2 hydrogenation by co-feeding ethanol to higher alcohols was performed with the HSC software package. The results suggested a high pressure and a low temperature for the reaction. However, it yielded low equilibrium compositions for the higher alcohols even at a high pressure of 100 bar at 300C . Increasing the equilibrium compositions for the higher alcohols can be done by removing water. A mathematical model was used to analyse the rate-limiting step in a process for the production of higher alcohols from CO2. In this process, reverse water gas shift (RWGS) reaction was used to convert CO2 to CO, subsequently, the obtained CO reacts with ethanol and hydrogen to produce higher alcohols directly. The mathematical model was developed in MATLAB to simulate how the reaction could behave by feeding CO2, H2 and ethanol at different pressures ranging from 10-200 bars. The water removal effect on the equilibrium is measured in terms of CO2 conversion by achieving 95% for removing water. The results indicated that the process can be used to convert CO2 to higher alcohols and at a lower pressure. The limiting factor for CO2 hydrogenation is the reaction mechanism, it’s an urgent problem for the development of the catalysts. In this model it was assumed to be a logistic function. The conversion of CO2 into higher alcohols is an important problem that is required to be addressed by more experimental verifications to understand the mechanism. The literature review shows that there is no available membrane for removal of water for the process currently, due to the harsh process conditions, mainly because of the membrane stability. However, membrane technology is a promising method for separation of water/organic mixtures that can be studied further in the future.

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Ingvarsdóttir, Anna. « Comparison of direct air capture technology to point source CO2 capture in Iceland ». Thesis, KTH, Kemiteknik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-289164.

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Det är välkänt att klimatförändringar på grund av global uppvärmning är en av de största kriserna som hotar jorden. Det är en enorm utmaning för mänskligheten att minska koldioxidutsläppen, den främsta orsaken till global uppvärmning. Enkelt genomförbara åtgärder är inte tillräckliga och teknik för att ta bort koldioxid från atmosfären anses nödvändig för att temperaturökningen inte ska överstiga de 1,5 °C som anges i Parisavtalet. Direkt infångning av koldioxid från luft (vanligen kallad direkt luftinfångning, (Eng. Direct air capture - DAC)) är en ny teknik som kan ta bort koldioxid direkt från atmosfären. För närvarande är denna metod dyr; upp till 1000 USD per ton avlägsnad koldioxid. Denna höga kostnad beror främst på den relativt låga koldioxidkoncentrationen i luften, vilket leder till att en stor anläggning behövs för att fånga upp gasen och därmed stora investeringar. Tekniken är mycket energiintensiv, antingen elektrisk eller termisk, och för att göra en direkt infångning effektivare, måste anläggningen drivas med energi som inte har några eller mycket låga koldioxidutsläpp. Energin på Island är billig och dess produktion innebär ett mycket lågt koldioxidavtryck. Syftet med arbetet i denna avhandling är att utforska om metoden för direkt infångning av koldioxid från luft kommer att vara en mer genomförbar metod än koldioxidinfångning från punktkällor (eng. point source - PS) på Island på grund av god tillgång till billig och ren energi. Lärandekurvan för direkt luftfångning studerades tillsammans med scenarier för metodens tekniska utveckling. Tre olika fall med punktkällor på Island studerades för jämförelse. Två olika direkta luftinfångningstekniker analyserades också, en som drivs av en stor mängd elektricitet och en som drivs mestadels av termisk energi. Det resulterade i att i bästa fall, där inlärningshastigheten är hög och tekniska förbättringar är signifikanta, så skulle produktionskostnaden för direkt luftinfångning (levelized cost of energy, LCOC) vara lägre än motsvarande för infångning från en punktkälla. Energikostnaden påverkar LCOC för DAC idag men med teknisk utveckling förväntas energibehovet minska och därför kommer energikostnadens påverkan att bli lägre. Det är dock fortfarande viktigt, med tanke på bidraget till att minska globala uppvärmningen, att energin som driver DAC-anläggningen har ett lågt koldioxidavtryck, vilket kan garanteras på Island. Tvärtom, om inlärningshastigheten för DAC-tekniken är låg och inga tekniska förbättringar sker i lösningsmedel eller sorbenter, är och kommer DAC-tekniken att bli dyrare än infångning från punktkällor om båda anläggningarna finns på Island. En hög inlärningshastighet och teknikutveckling är beroende av trycket att nå målen i Parisavtalet. Det är därför mycket viktigt för DAC att efterfrågan på koldioxidinfångning ökar. Dessutom har DAC mer potential att påverka klimatförändringarna eftersom DAC kan vara en kolnegativ teknik om den kombineras med permanent lagring av koldioxid. PS-avskiljningen kan endast vara en kolneutral teknik och detta om den kombineras med permanent lagring av koldioxid.
It is well known that climate change due to global warming is one of the greatest crises facing the Earth. It is a huge challenge for mankind to reduce CO2 emissions, the major cause of global warming. Mitigation measures are not enough. Technologies to remove the CO2 from the atmosphere are considered necessary, so the temperature rise does not exceed 1.5°C as stated in the Paris Agreement. Direct air capture (DAC) is a new technology that can remove carbon dioxide directly from the atmosphere. Currently, this method is expensive, up to 1000 USD per ton CO2 removed. This high cost is mostly due to the relatively low concentration of CO2 in the ambient air, leading to a large unit to capture the gas and therefore high capital investment. The technology is very energy-intensive, either electrical or thermal, and to make direct air capture more efficient the plant needs to be powered with energy that has no or very low CO2 emissions. The energy in Iceland is low cost and its production has a very low carbon footprint. This thesis aims to find out if the direct air capture method will be more feasible than a point source CO2 capture in Iceland due to good access to low-cost and clean energy. The learning curve for direct air capture was studied along with scenarios for its technological development. Two different direct air capture technologies were analyzed, one that is powered by a large amount of electricity and one powered mostly by thermal energy. Three different point source cases in Iceland were studied for comparison. For the best-case scenario, where the learning rate is high and technological improvements are significant, the levelized cost of direct air capture is lower than levelized cost of point source capture. The cost of energy affects the levelized cost of direct air capture today but with technical development, the energy needed is expected to go down, and therefore the effect of energy cost will be lower. However, it is still important, concerning contribution to reducing global warming, that the energy powering the direct air capture plant has a low carbon footprint, which can be assured in Iceland. On the contrary, if the learning rate of the direct air capture technology is low and no technical improvements occur in solvents or sorbents the direct air capture technology is and will be more expensive than point source capture considering both located in Iceland. The high learning rate and development in technology are dependent on the pressure to reach the goals of the Paris Agreement. It is therefore vital for direct air capture that the demand for carbon removal measures is enhanced due to pressure to reach the Paris Agreement goals. Furthermore, direct air capture has more potential to affect climate change than point source capture as direct air capture can be a carbon-negative technology if coupled with the permanent storage of CO2. The point source capture can only be a carbon-neutral technology if coupled with the permanent storage of CO2.

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Hu, Yukun. « CO2 capture from oxy-fuel combustion power plants ». Licentiate thesis, KTH, Energiprocesser, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-48666.

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To mitigate the global greenhouse gases (GHGs) emissions, carbon dioxide (CO2) capture and storage (CCS) has the potential to play a significant role for reaching mitigation target. Oxy-fuel combustion is a promising technology for CO2 capture in power plants. Advantages compared to CCS with the conventional combustion technology are: high combustion efficiency, flue gas volume reduction, low fuel consumption, near zero CO2 emission, and less nitrogen oxides (NOx) formation can be reached simultaneously by using the oxy-fuel combustion technology. However, knowledge gaps relating to large scale coal based and natural gas based power plants with CO2 capture still exist, such as combustors and boilers operating at higher temperatures and design of CO2 turbines and compressors. To apply the oxy-fuel combustion technology on power plants, much work is focused on the fundamental and feasibility study regarding combustion characterization, process and system analysis, and economic evaluation etc. Further studies from system perspective point of view are highlighted, such as the impact of operating conditions on system performance and on advanced cycle integrated with oxy-fuel combustion for CO2 capture. In this thesis, the characterization for flue gas recycle (FGR) was theoretically derived based on mass balance of combustion reactions, and system modeling was conducted by using a process simulator, Aspen Plus. Important parameters such as FGR rate and ratio, flue gas composition, and electrical efficiency etc. were analyzed and discussed based on different operational conditions. An advanced evaporative gas turbine (EvGT) cycle with oxy-fuel combustion for CO2 capture was also studied. Based on economic indicators such as specific investment cost (SIC), cost of electricity (COE), and cost of CO2avoidance (COA), economic performance was evaluated and compared among various system configurations. The system configurations include an EvGT cycle power plant without CO2 capture, an EvGT cycle power plant with chemical absorption for CO2 capture, and a combined cycle power plant. The study shows that FGR ratio is of importance, which has impact not only on heat transfer but also on mass transfer in the oxy-coal combustion process. Significant reduction in the amount of flue gas can be achieved due to the flue gas recycling, particularly for the system with more prior upstream recycle options. Although the recycle options have almost no effect on FGR ratio, flue gas flow rate, and system electrical efficiency, FGR options have significant effects on flue gas compositions, especially the concentrations of CO2 and H2O, and heat exchanger duties. In addition, oxygen purity and water/gas ratio, respectively, have an optimum value for an EvGT cycle power plant with oxy-fuel combustion. Oxygen purity of 97 mol% and water/gas ratio of 0.133 can be considered as the optimum values for the studied system. For optional operating conditions of flue gas recycling, the exhaust gas recycled after condensing (dry recycle) results in about 5 percentage points higher electrical efficiency and about 45 % more cooling water consumption comparing with the exhaust gas recycled before condensing (wet recycle). The direct costs of EvGT cycle with oxy-fuel combustion are a little higher than the direct costs of EvGT cycle with chemical absorption. However, as plant size is larger than 60 MW, even though the EvGT cycle with oxy-fuel combustion has a higher COE than the EvGT cycle with chemical absorption, the EvGT cycle with oxy-fuel combustion has a lower COA. Further, compared with others studies of natural gas combined cycle (NGCC), the EvGT system has a lower COE and COA than the NGCC system no matter which CO2 capture technology is integrated.
QC 20111123

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Westman, Snorre Foss. « Power plant with CO2 capture based on adsorption ». Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for energi- og prosessteknikk, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-18504.

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A dynamic one-dimensional homogeneous model for a packed bed sorption-enhanced water-gas shift (SEWGS) reactor has been developed, describing the non-isothermal, non-adiabatic and non-isobaric operation of this type of reactor. The model was developed to describe a SEWGS reactor designed to work under operating conditions and syngas feeds encountered in a coal-fed Integrated Gasification Combined Cycle power plant utilizing an oxygen-fed gasifier. Different from previous integration designs reported in literature, the feasibility of leaving out the conventional high-temperature water-gas shift (WGS) reactor upstream of the SEWGS reactor has been investigated. The reactor was assumed to be packed with a mixture of K2CO3-promoted hydrotalcite CO2 adsorbent and commercial high-temperature FeCr-based water-gas shift catalyst pellets. Utilizing the reactor model, a mathematical modelling framework for the operation of eight SEWGS reactors in a SEWGS cycle has been developed. This system model accounts for all the necessary interactions between the reactors during the SEWGS cycle, including the exchange of mass in the feed, rinse, equalization and repressurization steps. In contrast to available open literature, the mathematical framework describes in detail how the necessary switches in the boundary conditions for the reactors have been realized.Simulations of several SEWGS cycles were carried out. The results were compared with experimental and modelling data from literature. Due to inconsistencies in the parameters and implementation of the model in the simulation software employed, results were in most aspects quantitatively not comparable to results from literature. However, the qualitative trends and physical mechanisms expected were observed and confirmed by the model. The temperatures in the reactors reached an unacceptable high level with respect to the tolerable operating conditions of the catalyst and adsorbent. It is planned to continue the work on the model, and implementing it within a full power plant model to investigate the effects of changes in the power production and thus the required amount of syngas to be treated.

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Ekre, Kjetil Vinjerui. « Novel Processes for Power Plant with CO2 Capture ». Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for energi- og prosessteknikk, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-19372.

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The purpose of this thesis was to examine different technologies, which enhances the CO2 partial pressure in the flue gas from the natural gas combined cycle. A base case has been created as a reference for comparison of the other cycles. The base case includes a MEA capture plant with a reboiler duty of 3,6 MJ/kg CO2. To simulate the process in this thesis HYSYS and GT PRO have been used as simulation tools. The thesis has also looked into ways of extracting steam from the steam cycle to be used in the reboiler. The chosen extraction point was the crossover between the intermediate-pressure turbine and the low-pressure turbine, the steam was saturated with water from the low-pressure boiler and have a pressure and temperature of 3,6 bar and 140 °C into the reboiler. Four different technologies have been evaluated in this thesis; a natural gas combined cycle with the use of exhaust gas recycle and, three elevated pressure cycles; post-compression CO2 capture, post-expansion CO2 capture, and tail-end CO2 capture. These processes have been compared against each other with regards to the net plant efficiency, absorber size at the capture plant, and the technological maturity. The most promising of these technologies is the natural gas combined cycle with exhaust gas recycle and the tail-end CO2 capture processes, with respectively 52 % and 51,7 % net plant efficiency. The smallest absorber size is achieved by the use of post-compression CO2 capture, with a diameter of 2,9 m and a height of 10,5 m. The elevated pressure cycles have also been tested with the use of MDEA as solvent in the capture plant. By use of elevated pressure and MDEA the reboiler duty was reduced to 2 MJ/ kg CO2.

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Champagne, Scott. « Steam Enhanced Calcination for CO2 Capture with CaO ». Thèse, Université d'Ottawa / University of Ottawa, 2014. http://hdl.handle.net/10393/30905.

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Carbon capture and storage technologies are necessary to start lowering greenhouse gas emissions while continuing to utilize existing thermal power generation infrastructure. Calcium looping is a promising technology based on cyclic calcination/carbonation reactions which utilizes limestone as a sorbent. Steam is present in combustion flue gas and in the calciner used for sorbent regeneration. The effect of steam during calcination on sorbent performance has not been extensively studied in the literature. Here, experiments were conducted using a thermogravimetric analyzer (TGA) and subsequently a dual-fluidized bed pilot plant to determine the effect of steam injection during calcination on sorbent reactivity during carbonation. In a TGA, various levels of steam (0-40% vol.) were injected during sorbent regeneration throughout 15 calcination/carbonation cycles. All concentrations of steam were found to increase sorbent reactivity during carbonation. A level of 15% steam during calcination had the largest impact. Steam changes the morphology of the sorbent during calcination, likely by shifting the pore volume to larger pores, resulting in a structure which has an increased carrying capacity. This effect was then examined at the pilot scale to determine if the phase contacting patterns and solids heat-up rates in a fluidized bed were factors. Three levels of steam (0%, 15%, 65%) were injected during sorbent regeneration throughout 5 hours of steady state operation. Again, all levels of steam were found to increase sorbent reactivity and reduce the required sorbent make-up rate with the best performance seen at 65% steam.

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Parker, Qamreen. « Molecular simulations of ionic liquids for CO2 capture ». Thesis, University College London (University of London), 2018. http://discovery.ucl.ac.uk/10048467/.

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Ionic liquids (ILs) are molten salts at temperatures below 100 °C or at room temperature, achieving this by possessing ions that pack weakly, preventing the formation of a stable crystal lattice. The very low or non-existent volatility of the liquids is one of the most important reasons for why ILs are explored for carbon dioxide (CO2) capture, along with interesting properties such as thermal stability, nonflammability and tunability for high CO2 solubility. It is therefore important to understand, at a molecular level, the structure and properties of ILs. The work presented in this thesis employs classical molecular dynamics (MD) simulations to investigate ILs at varying temperature and varying loadings of CO2. Initially, the interatomic potentials or force field (FF) that can be used to simulate ILs are researched, before choosing two: The Generalised Amber FF (GAFF) and Canongia Lopez and Padua FF (CL&PFF). After a comparison of densities and structures resultant, further validation on the CL&PFF is reported. Subsequently, a phosphonium based IL, [P66614][NTf2], is investigated in a pure state at varying temperatures, to compare with experimental data. We study the density, structure and diffusion of the system, in terms of cation, anion and ion pair. We reinforce the results of our initial FF comparison, as the density is calculated to a high degree of accuracy compared with experiment. We continue to describe the influence of temperature on the structure and dynamics, comparing with experimental data where available. Finally, we considered the IL’s reported CO2 solubility and explored different loadings of CO2 in the IL system. We observe significant changes in IL structure and diffusion with even small loadings of CO2, along with interesting CO2 interactions and diffusion. Following on from this, we detail the initial modelling of a phosphonium based superbase ionic liquid, with a combination of FFs and scaling of atomic charges to better detail the diffusivity of the IL. Thus, in this thesis, we present ILs as a media that offers significant performance benefits when compared to traditional organic solvents for carbon capture. Additionally, we confirm the suitability of MD simulations for the accurate description and elucidation of structural and diffusive properties of ILs.

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Amara, Soumia. « CO2 capture in industry using chilled ammonia process ». Thesis, KTH, Energiprocesser, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-292504.

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CO2 capture and storage (CCS) is estimated to reduce 14% of the global CO2 emissions in the 2 °C scenario presented by the International Energy Agency. Moreover, post combustion capture is identified as a potential method for CO2 capture from industry since it can be easily retrofitted without disturbing the core industrial process. Among the post-combustion capture methods, absorption using mono-ethanol amine (MEA) is the most mature technology that has been demonstrated at plant scale. However, using chilled ammonia process as a post combustion capture technology in a cement industry can reduce 47% energy penalty for CO2 capture when compared to the conventional MEA absorption method. Hence, the current project aims at analyzing the chilled ammonia process when integrated with steel and ammonia plants. Key performance indicator like specific primary energy consumption per kilogram of CO2 avoided (SPECCA) is estimated and compared with MEA absorption method. Firstly, chilled ammonia process (CAP) for cement plant was used as reference case. Then, CAP for steel and ammonia processes was optimized by the means of the decision variables affecting the capture and energy efficiency. The energy consumption per kg CO2 captured and SPECCA was lower for the higher CO2 concentration in the flue gas. Results for SPECCA were 3,56, 3,52 and 3,61 MJ/kg CO2 for cement, steel, and ammonia plants, respectively.

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Higgins, Stuart James. « Design and Optimization of Post-Combustion CO2 Capture ». Diss., Virginia Tech, 2016. http://hdl.handle.net/10919/80003.

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This dissertation describes the design and optimization of a CO2-capture unit using aqueous amines to remove of carbon dioxide from the flue gas of a coal-fired power plant. In particular we construct a monolithic model of a carbon capture unit and conduct a rigorous optimization to find the lowest solvent regeneration energy yet reported. Carbon capture is primarily motivated by environmental concerns. The goal of our work is to help make carbon capture and storage (CCS) a more efficient for the sort of universal deployment called for by the Intergovernmental Panel on Climate Change (IPCC) to stabilize anthropomorphic contributions to climate change, though there are commercial applications such as enhanced oil recovery (EOR). We employ the latest simulation tools from Aspen Tech to rigorously model, design, and optimize acid gas systems. We extend this modeling approach to leverage Aspen Plus in the .NET framework through Microsoft's Component Object Model (COM). Our work successfully increases the efficiency of acid gas capture. We report a result optimally implementing multiple energy-saving schemes to reach a thermal regeneration energy of 1.67 GJ/tonne. By contrast, the IPCC had reported that leading technologies range from 2.7 to 3.3 GJ/tonne in 2005. Our work has received significant endorsement for industrial implementation by the senior management from the world's second largest chemical corporation, Sinopec, as being the most efficient technology known today.
Ph. D.

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Molinder, Roger Axel. « CO2 capture materials for sorption enhanced steam reforming ». Thesis, University of Leeds, 2012. http://etheses.whiterose.ac.uk/2871/.

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The Ca-looping cycle is a chemical process that alternates capture and release of CO2 using a Ca-based sorbent which can be applied to hydrogen production by steam reforming. Adding sorbent particles to the reformer achieves nearly pure hydrogen with higher yields via the ‘sorption enhancement’ effect. The major disadvantage is deactivation of the sorbent following multiple cycles and suggested solutions have been incorporation of inert material and regeneration by hydration. This work investigates Ca-based sorbents with a focus on their use for steam reforming of liquid feedstock. Thermodynamic analysis was used to understand the equilibrium of the steam reforming of three different feedstocks with and without CaO as the sorbent. Addition of sorbent significantly increased the H2 yield and the H2 molar fraction for all three feedstocks. Inert material was incorporated into CaO and CaO derived from Ca-D-gluconate. The resulting sorbents were investigated using thermogravimetric analysis (TGA) and a bench scale reactor in combination with X-ray diffraction (XRD) and N2 adsorption. Incorporation resulted in a reduction in pores in the 50-100 nm size range and caused self-reactivation behaviour over multiple cycles. The capture capacity and morphology of the sorbent was altered by the CaO precursor but XRD spectra were not. In situ XRD coupled with Rietveld refinement yielded new insights into the mechanism of Ca-based carbonation and sorbent stability. Agreement between in situ XRD and TGA data was found for carbonation of CaO and Ca(OH)2, and the mechanism of CO2 capture in partially hydrated CaO was investigated. Ca(OH)2 formed CaCO3 without the CaO intermediate, and anisotropic diffraction peak broadening was observed in the partially hydrated sorbent. Steam reforming of ethanol and glycerol with and without a Ca-based sorbent was investigated using a novel reactor featuring a nichrome resistance wire with a heating element/catalyst double function. Wire morphology had significant impact on feedstock conversion and the activity of the wire could be increased using a redox pretreatment which caused the formation of chromium oxides on the wire surface. The addition of sorbent by coating resulted in CO2 capture but not sorption enhancement. The coating also hindered water gas shift and eroded with time on stream.

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Bernadet, Sophie. « Conversion photocatalytique du CO2 sur monolithes poreux ». Thesis, Bordeaux, 2018. http://www.theses.fr/2018BORD0172/document.

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Dans le contexte actuel de développement de nouvelles sources d'énergie non fossiles tout en minimisant l'impact environnemental, la production de carburants solaires par la valorisation des émissions anthropiques de CO2 apparaît comme une solution à fort potentiel. Le principal défi dans les processus artificiels photo-induits concerne le caractère bidimensionnel des systèmes utilisés, en raison de la faible profondeur de pénétration des photons. Ce travail de thèse se concentre sur le développement de mousses solides alvéolaires, issues de la chimie intégrative, présentant une porosité hiérarchiquement organisée. A travers l’imprégnation de précurseurs de TiO2, des photocatalyseurs autosupportés ont été synthétisés et ont montré une augmentation de la pénétration des photons d’un ordre de grandeur. D’autre part, ces solides limitent les réactions inverses par un effet de dilution, tout en assurant une sélectivité élevée envers la génération d'alcanes. Un modèle cinétique, basé sur un formalisme mixte de Langmuir-Hinshelwood et Eley-Rideal, est proposé pour décrire le comportement des matériaux
In the current context of developing novel non-fossil energy sources while minimizing the environmental impact, solar-driven-fuel-production by exploiting anthropogenic CO2 emissions appears to be a solution with great potential. The main challenge in artificial photo-induced processes concerns the two-dimensional character of the systems used, due to the low photon penetration depth. This thesis work focuses on the development of alveolar solid foams, derived from integrative chemistry and bearing a hierarchically organized porosity. By TiO2 precursor impregnation, self-standing photocatalysts were synthesized and provided a photon penetration increase by an order of magnitude. Moreover, these solids limit back-reactions by a dilution effect, while ensuring high selectivity towards alkane generations. A kinetic model, based on a mixed formalism of Langmuir-Hinshelwood and Eley-Rideal, is proposed to describe material behavior

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TARRARAN, LOREDANA. « Microbial CO2 conversion to value-added products ». Doctoral thesis, Politecnico di Torino, 2022. http://hdl.handle.net/11583/2967854.

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Nogalska, Adrianna. « Ambient carbon dioxide capture and conversion via membranes ». Doctoral thesis, Universitat Rovira i Virgili, 2018. http://hdl.handle.net/10803/664718.

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El canvi climàtic causat per l'augment del contingut de CO2 a l'atmosfera està causant gran preocupació avui dia. La constant necessitat de generació d'energia verda ens va inspirar a desenvolupar un sistema fotosintètic artificial. El sistema funciona com un full, on el CO2 es capta directament de l'aire a través dels porus de la membrana i passa als següents compartiments per convertir-se finalment en metanol o altres hidrocarburs i serà utilitzat com a combustible. L'objectiu principal del treball és revelar la influència dels contactors de membrana basats en polisulfona sobre la taxa de captura de CO2 atmosfèric mitjançant absorció química en solucions aquoses. Les membranes de làmines planes que varien en morfologia es van preparar per precipitació i es van sotmetre a caracterització de morfologia interna i de la superfície. La membrana de polisulfona es va modificar amb una sèrie d'additius coneguts per l'afinitat de CO2, com ara: nenopartículas de ferrita, carbó activat i enzims. A més, la compatibilitat entre les membranes i la solució absorbent es va avaluar en termes de mesures d'inflament i angle de contacte. A més, es van realitzar estudis preliminars sobre la conversió de CO2 capturada en combustibles amb l'ús d'una unitat electroreductora. Els estudis van mostrar que el sistema basat en polisulfona té una assimilació de CO2 superior en comparació amb el rendiment d'un full. A més, els millors resultats es van obtenir utilitzant una membrana en blanc i sense modificar, el que proporciona un baix cost de producció. A més, es va aconseguir la conversió de bicarbonat a àcid fòrmic, donant un començament prometedor per millorar en el treball futur.
El cambio climático causado por el aumento del contenido de CO2 en la atmósfera está causando gran preocupación hoy en día. La constante necesidad de generación de energía verde nos inspiró a desarrollar un sistema fotosintético artificial. El sistema funciona como una hoja, donde el CO2 se capta directamente del aire a través de los poros de la membrana y pasa a los siguientes compartimentos para convertirse finalmente en metanol o otros hidrocarburos y sera utilizado como combustible. El objetivo principal del trabajo es revelar la influencia de los contactores de membrana basados en polisulfona sobre la tasa de captura de CO2 atmosférico mediante absorción química en soluciones acuosas. Las membranas de láminas planas que varían en morfología se prepararon por precipitación y se sometieron a caracterización de morfología interna y de la superficie. La membrana de polisulfona se modificó con una serie de aditivos conocidos por la afinidad de CO2, tales como: nenopartículas de ferrita, carbón activado y enzimas. Además, la compatibilidad entre las membranas y la solución absorbente se evaluó en términos de medidas de hinchamiento y ángulo de contacto. Además, se realizaron estudios preliminares sobre la conversión de CO2 capturada en combustibles con el uso de una unidad electroreductora. Los estudios mostraron que el sistema basado en polisulfona tiene una asimilación de CO2 superior en comparación con el rendimiento de una hoja. Además, los mejores resultados se obtuvieron utilizando una membrana en blanco y sin modificar, lo que proporciona un bajo costo de producción. Además, se logró la conversión de bicarbonato a ácido fórmico, dando un comienzo prometedor para mejorar en el trabajo futuro.
The climate change caused by the increased CO2 content in the atmosphere is raising a lot of concern nowadays. The constant need for sustainable green energy generation inspired us to develop an artificial photosynthetic system. The system works as a leaf, where CO2 is captured directly from air through the membrane pores and passes to the next compartments to be finally converted to methanol or other hydrocarbons and to be further used as fuel in fuel cells. The main scope of the work is to reveal the influence of polysulfone -based membrane contactors on atmospheric CO2 capture rate by chemical sorption into absorbent aqueous solutions. Flat sheet membranes that vary in morphology were prepared by immersion precipitation and undergo internal morphology and surface characterization. The polysulfone membrane was modified with a number of additives known for the CO2 affinity such as: ferrite nenoparticles, activated carbon and enzymes. Moreover, the compatibility between membranes and absorbent solution was evaluated in terms of swelling and contact angle measurements. Additionally, preliminary studies concerning the captured CO2 conversion to fuels were performed with use of electro-reductive unit. Studies showed that the polysulfone based system has superior CO2 assimilation compared to a leaf performance. Moreover, the best results were obtained using blank and unmodified membrane, providing a low production cost. Furthermore, the conversion of bicarbonate to formic acid was achieved, giving a promising start to be improved in future work.

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Bilsbak, Vegard. « Conditioning of CO2 coming from a CO2 capture process for transport and storage purposes ». Thesis, Norwegian University of Science and Technology, Department of Energy and Process Engineering, 2009. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-9943.

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VITTONI, CHIARA. « Hybrid Organic-Inorganic Materials for CO2 Capture and Utilization ». Doctoral thesis, Università del Piemonte Orientale, 2018. http://hdl.handle.net/11579/97188.

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In this PhD thesis, different types of hybrid organic-inorganic materials were studied as solid sorbents for the carbon dioxide capture, in order to give additional hints to the comprehension of phenomena playing an important role in CO2 adsorption processes. In the first part, hybrid organic-inorganic SBA-15 silicas functionalized with variable amount of amino groups were studied aiming to evaluate the influence of the different basic species on CO2 capture ability. Afterwards, it was decided to study the influence of siliceous support properties on the adsorption process. For this purpose, silica-based materials with different structure, morphology and particle size were selected and tested in the same experimental conditions, aiming to understand the effect of their physico-chemical properties on the CO2 adsorption. On one side MCM-41 silica-based materials with different particle diameter, passing from micrometric to nanometric scale, were considered, in order to study the size effect of the support on the adsorption properties. Furthermore, the effect of the porosity was evaluated by using as adsorbent a non-porous material (Stöber silica) and comparing the obtained results with those of MCM-41-based materials. Finally, the possible use of silica-based materials as catalyst for the carbon dioxide transformation into more useful products was studied. In particular, heterogeneous Cu-based catalyst supported on SiO2 have been studied as for the promotion of hydrogenation reaction of CO2 to formic acid.

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Busu, Alice. « Development of PVA/PDA nanocomposite membranes for CO2 capture ». Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020.

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In this project, composite membranes containing nanoparticles of polydopamine PDA (dopamine polymer) will be manufactured and characterized in view of their use for the separation of CO2. Polysulfone will be used as a polymer matrix support while poly(vinyilalcohol) has been chosen as selective layer material. The work will first focus on the optimization of the manufacturing parameters of nano composite membranes and then on the influence of the integration of PDA nanoparticles in the polymeric support at different concentrations. The final objective is to test the material properties, with particular reference to the separation performances of the membranes produced, and critically comment on the results obtained.

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Baig, Yasir. « Technology qualification for IGCC power plant with CO2 Capture ». Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for energi- og prosessteknikk, 2011. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-14712.

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Summary:This thesis presents the technology qualification plan for the integrated gasification combined cycle power plant (IGCC) with carbon dioxide capture based on DNV recommendations. Objectives of the thesis work were development of a qualification plan, heat balance, material balance and performance characteristics for IGCC with CO2 capture. GT PRO software by thermoflow was used for the development of heat balance, material balance and performance characteristics of power plant.IGCC with pre-combustion capture is a process of generating power with very low CO2 emissions. The IGCC process gasifies coal to a syngas, converts the CO to CO2 in the shift reactors, separates the CO2 in the capture subsystem, and the resulting fuel is used for the gas turbine (GT) in a combined cycle setup. A comparison is also made between the enriched air blown gasification combined cycle power plant with CO2 capture and shell gasification combined cycle power plant with CO2 capture. For the case of this thesis, technology qualification steps obtained from DNV guidelines are implemented on the enriched air blown integrated gasification power plant with CO2 capture. First step of the technology qualification was to establish a qualification basis for the IGCC power plant with CO2 capture. In this step detailed process description of power plant is done in order to define what technology should do and what its functional requirements are?Next step of the technology qualification was technology assessment. The main purpose of this step was to divide the IGCC power plant with CO2 capture into manageable elements that involve the aspects of new technology and identify key challenges and uncertainties associated with those novel elements.Threat assessment was the third step in the technology qualification. Risks and failure modes associated with the commercialization of IGCC with CO2 capture are identified by applying risk assessment techniques like (Failure Mode Effect & Criticality Analysis (FMECA) and Hazard and Operability Analysis (Hazop). Analysis of variance was used in order to give priority to more critical failure modes.Faiure modes like surge problem of gas turbine,fouling,metal dusting and tube vibration for the heat exchanger, deactivation of catalyst for shift reactor, maldistribution of the solvent for the absorber, contaminated supply of steam to steam turbine have been identified.Qualification plans were developed for the identified failure modes of concern obtained from FMECA and Hazop analysis .The main objective of this step was to select qualification activities that adequately address the identified failure modes of concern with respect to its risk and determination of sufficient performance margins. Activities like integration of gas turbine to air separation unit, chemical treatment of water in order to avoid contaminated supply of water to HRSG and contaminated supply of steam to steam turbine, better understanding of distributor design and packing development for the absorber were suggested.After the selection of these qualification activities, execution of selected qualification activities was done in a systematic manner to document performance margins for the failure modes of concern.Last step of the technology qualification plan was concept improvement. The objective of the concept improvement step was to implement improvements that have been found necessary or beneficial during the failure mode identification and risk ranking or in the performance assessment.The focus of this work was to reduce uncertainties in these parameters in order to improve the confidence in the IGCC power plant with CO2 capture.

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Samari, Mohammad. « CO2 Capture from Dilute Sources via Lime-Based Sorbents ». Thèse, Université d'Ottawa / University of Ottawa, 2014. http://hdl.handle.net/10393/30978.

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Direct capture of CO2 from ambient air is a developing technology, which is capable of removing CO2 directly from the atmosphere. Moreover, this technology is independent from sources of CO2 emissions. Hence, it can be set up at locations where pure stream of CO2 is needed such as in enhanced oil recovery. In this research, the performance of pelletized and natural limestone for CO2 capture from air in a fixed bed is studied. To compare the performance of sorbents for air capture, the effects of particle type (natural limestone and pelletized limestone), particle size (250-425 µm and 425-600 µm), gas flowrate (0.5 L/min and 1 L/min), and relative humidity, on the breakthrough time, breakthrough shape, and the global reaction rate are examined. Moreover, carbonation decay of sorbents over series of capture and regeneration cycles is studied. If the inlet stream (air) is humidified at 50% relative humidity, but the lime sorbents are not pre-hydrated, an axially non-uniform carbonated bed results. This phenomenon is due to the partial carbonation of sorbents at the first layers of the bed. While there is a competition between CO2 and water to react with CaO, partial carbonation reaction on the surface of the sorbents not only prevents further hydration, but also decreases the reaction rate at the surface. However, in comparison with a dry system where relative humidity was negligible and sorbents were not pre-hydrated, the observed carbonation conversion was higher. The best results were seen from experiments with pre-hydrated sorbents and humidified inlet stream. The smaller sorbent particles had a better performance (sharper breakthrough curve and longer breakthrough time) due to their greater surface area. A gas-solid reaction model was fitted to the breakthrough curves. Since at the beginning of carbonation there is no resistance of the product layer, it can be assumed that the process is reaction controlled. While after formation of the product layer (CaCO3), it becomes diffusion controlled. Results from fitted data also confirmed these conclusions. Moreover, each of sorbent went through 9 cycles and after each cycle the carbonation conversion of the sorbents was measured by TGA and the surface area by BET.

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Stene, Henrik Sørskår, et Ole Marius Moen. « Power Plant with CO2 Capture based on PSA Cycle ». Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for energi- og prosessteknikk, 2014. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-26240.

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Two coal-fired power plants with CO2 capture by Pressure Swing Adsorption (PSA) havebeen modeled and simulated. The two power plants considered were IntegratedGasification Combined Cycle (IGCC) and conventional Pulverized Coal Combustion (PCC). Amathematical model of the PSA process for each of the power plants was developed and thegoal was to evaluate the feasibility of PSA as a technology for decarbonisation. Theperformance with CO2 capture by PSA was compared to a reference plant without CO2capture and to a power plant with CO2 capture by absorption, which is considered as thebenchmark technology. The size and number of the PSA columns were estimated todetermine the footprint.For the PCC power plant, the PSA model was a two-stage process consisting of a front and a tail stage. Two-stages mean that it consisted of two consecutive PSA processes. The front stage was a three-bed, five-step Skarstrom process with rinse. The tail stage was a two-bed, five-step Skarstrom process with pressure equalization. Zeolite 5A was used as adsorbent. For a specified capture rate of 90.0 %, the process achieved a purity of 96.4 % and a specific power consumption of 1.3 MJ/kgCO2. The net plant efficiency dropped 16.6 percentage points from 45.3 % to 28.7 % when introducing CO2 capture by PSA. In comparison, the PCC plant using absorption achieved a net plant efficiency of 33.4 %. The results indicate that the current state of the art PSA technology for decarbonisation as an alternative to absorption is not realistic for PCC power plants.For the IGCC power plant, the PSA model was a seven-bed, twelve-step Skarstromconfiguration with four pressure equalization steps using activated carbon as adsorbent. The process achieved a purity of 87.8 % and a capture rate of 86.3 % with negligible power consumption. The PSA process did not satisfy the performance targets of 90 % recovery and 95.5 % purity, and due to the low purity it is uncertain whether or not transport and storage of CO2 is at all feasible. The net plant efficiency dropped 12.5 percentage points from 47.3 % to 34.8 %. In comparison the IGCC plant with absorption achieved a net plant efficiency of 36.4 %. The results showed that PSA as a capture technology for IGCC power plants could not perform quite as well as absorption. However, PSA as a capture technology could have a potential if the purity could be increased, and is therefore more promising than PSA for PCC power plants.

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Biyouki, Zeinab Amrollahi. « Thermodynamic analysis of CO2 capture processes for power plants ». Doctoral thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for energi- og prosessteknikk, 2014. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-26380.

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This thesis work presents an evaluation of various processes for reducing CO2 emissions from natural-gas-fired combined cycle (NGCC) power plants. The scope of the thesis is to focus mainly on post-combustion chemical absorption for NGCC. For the post-combustion capture plant, an important interface is the steam extraction from the steam turbine in order to supply the heat for solvent regeneration. The steam extraction imposes a power production penalty. The thesis includes analysis and comparison between several chemical absorption processes configurations integrated with NGCC. The objectives of the present work were to use thermodynamic analysis on various chemical absorption process configurations to evaluate, quantify and justify improved design of NGCC with post-combustion CO2 capture. The thermodynamic evaluation of the processes gave insight to the detailed distribution of process irreversibilities and supports the state-of-the-art process configuration with the lowest energy penalty due to addition of CO2 capture to the power plant. The reference power plant without CO2 capture has a power production of 384 MW and a net electric efficiency of 56.4% (LHV) with CO2 emissions of ≈ 362 g CO2/ net kWh electricity. The power plant design was carried out using the computational tool GTPRO. The aim of the CO2 capture plant was to remove 90% of the CO2 emissions present in the flue gas. To assess and analyse the various chemical absorption process configurations, the UniSim Design software was used, which contains the Amines Property Package. This special property package has been designed to aid the modelling of alkanolamine treating units in which CO2 is removed from gaseous streams. The downstream compression of the captured CO2 was also simulated using UniSim Design. The investigated process configurations were comprised of chemical absorption process with absorber inter-cooling, split-flow process and lean vapour recompression (LVR) process. Several design parameters were modified for each of the process configurations to achieve low energy consumption and consequently low work demand. The inter-cooling of the absorber column led to increased solvent rich loading. Consequently, the solvent circulation rate and reboiler energy requirement was decreased. In the split-flow configuration, due to splitting of the rich solvent into two streams, the amount of rich solvent entering the bottom section of the stripper was reduced. Therefore, less reboiler energy was required to remove CO2 from the solvent to reach the same solvent lean loading as of the reference chemical absorption process. In the configuration with lean vapour recompression (LVR), the lean solvent stream was utilised as a low temperature heat source in order to add exergy input in the form of steam to the stripper column and thus reduce the reboiler duty. The reboiler duty for the CO2 capture was decreased from 3.74 MJ/kgCO2 in the reference chemical absorption process to 2.71 MJ/kgCO2 for the case of LVR with absorber inter-cooling. The net electric efficiency of the reference process with CO2 capture was calculated to 49.5% (LHV). With the improved process design, the highest net power plant efficiency was calculated to 50.2 % (LHV) for the case of LVR with absorber inter-cooling. Moreover, exergy analysis was performed to identify the irreversibilities associated with the integration of power plant with various CO2 capture and compression processes. Particularly, the second law of thermodynamics was used as a tool to evaluate and quantify the reduction of energy penalty associated with CO2 capture for each process modification. Defining the work input for a theoretical reversible CO2 capture process as the minimum required work was functional step in characterising the difference of the work input of theoretical reversible processes and the real irreversible processes. Exergy efficiency of the reference chemical absorption process was calculated to 21.3 % versus 25 % for the case of LVR with absorber inter-cooling. Through exergy balance for every CO2 capture process configuration, the exchange of exergy content of material and energy streams was assessed. Using the combination of power plant efficiency and exergy analysis as tools, a pre-combustion reforming combined cycle (IRCC) process with chemical absorption CO2 capture process was investigated. A rational efficiency of 43.8% was achieved, which indicates the share of input exergy utilised for work production by the power cycle in addition to the exergy of the pure compressed CO2 stream. The highest amount of irreversibility was contributed by the gas turbine and mainly by the combustor. The irreversibility which is inherent in the combustion process corresponded to a large fraction of original exergy of the fuel. This could be partially compensated by increase the preheating of the fuel supplied to the combustor. Also preheating the inlet streams to auto-thermal reactor (ATR) was found advantageous in decreasing the ATR irreversibilities.

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Ali, Usman. « Process simulation of power generation systems with CO2 capture ». Thesis, University of Sheffield, 2017. http://etheses.whiterose.ac.uk/16011/.

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The increase in the anthropogenic greenhouse gases has severely damaged the environment in terms of pollution and global climate change. It is capturing the carbon dioxide from the present and future power plants that could save the climate. The post-combustion CO2 capture system using amine wet scrubbing is investigated in detail for natural-gas fired power plant from pilot-scale to commercial-scale level. The research work is focused on the investigation of the different innovative modifications to the micro gas turbine (MGT) including exhaust gas recirculation (EGR), steam injection and humid air turbine. The process models are developed for both MGT and pilot-scale amine-based CO2 capture plant. The MGT model is tuned and validated with extensive experimental data at different part load conditions for base case, CO2, steam and simultaneous CO2 and steam injection to the default MGT. The thermodynamic behaviour, emissions, system efficiency and the sensitivity of the base case MGT for ambient conditions are explored. The robust model is extended for EGR, steam injection and humid air turbine system models; and process system performance comparison for the different modifications is assessed for possible recommendation. In addition, the impact of the operating conditions and locations of the EGR on the performance of the MGT is also analysed. Further, the effect of the enhanced CO2 on the extensively validated pilot-scale amine-based CO2 capture plant integrated with MGT is examined. In addition, the sensitivity analysis of the pilot-scale amine-based CO2 capture model is studied to quantify the effect of the operating parameters on the system performance and to estimate the optimum operating envelope. The EGR at 55 % resulted in a 20.5 % decrease in specific reboiler duty from the pilot-scale amine-based CO2 capture plant at the CO2 capture rate of 90 % for monoethanolamine at 30 wt. % aqueous solution. Furthermore, a techno-economic process design and/or scale-up of the commercial-scale amine-based CO2 capture system to service about 650 MWe of the natural gas-fired power plant system with and without EGR is investigated for varying EGR percentage. Finally, thorough comparative potential for the natural gas, coal, biomass fired and co-firing of coal and biomass power plants integrated with CO2 capture and CO2 compressions system are explored for different cases of each power plant. The biomass firing resulted in about 40 % increase in fuel flow rate for the constant heat input case while it resulted in 30 % derating of the power output for the constant fuel flow rate case. The comparative potential of gas-CCS, coal-CCS and BECCS has shown that the NGCC with EGR resulted in the least efficiency penalty on integration with CO2 capture and compression system due to the higher net efficiency. However, coal and biomass fired power plant resulted in the least specific losses per unit of the CO2 capture on integration with CO2 capture and compression system due to the higher specific CO2 capture.

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Esam, Odette Amana. « CO2 Capture on Porous Adsorbents Containing Surface Amino Groups ». Digital Commons @ East Tennessee State University, 2013. https://dc.etsu.edu/etd/2304.

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The potential impact of carbon dioxide as a major source of global warming has led to extensive research in order to mitigate the greenhouse effect. In this work, four adsorbents were synthesized and studied. The adsorbents were obtained by grafting and sol-gel of amino-containing molecules such as bis[3-(trimethoxysilyl)propyl]amine as monoamine and [3-(2-aminoethylamino)propyl]- trimethoxysilane as diamine on the surface of silica gel. CO2 passed through adsorbents at room temperature for its capture, then desorbed at moderate heating, and stored in the form of insoluble BaCO3. The adsorbent synthesized by sol-gel synthesis was found to be more efficient due to its high content of amino groups. A demonstration experiment on reversible adsorption of CO2 on mesoporous modified silica gel was developed. This experiment visualizes a technology of post-combustion CO2 sequestration from industrial emission gases and its storage.

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GILLONO, MATTEO. « 3D printable materials for CO2 capture and separation technologies ». Doctoral thesis, Politecnico di Torino, 2020. http://hdl.handle.net/11583/2827712.

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Amado, Verónica Catarina Ferreira. « “One-pot” enzymatic conversion of CO2 to methanol ». Master's thesis, Faculdade de Ciências e Tecnologia, 2013. http://hdl.handle.net/10362/10900.

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MOROSANU, EDUARD ALEXANDRU. « Catalytic processes for CO2 conversion into Synthetic Methane ». Doctoral thesis, Politecnico di Torino, 2020. http://hdl.handle.net/11583/2841162.

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LIENDO, CASTILLO FREDDY JESUS. « CO2 conversion through the synthesis of CaCO3 nanoparticles ». Doctoral thesis, Politecnico di Torino, 2021. http://hdl.handle.net/11583/2907014.

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Kolle, Joel Motaka. « Mesoporous Organosilicas for CO2 Capture and Utilization : Reaction Insight and Material Development ». Thesis, Université d'Ottawa / University of Ottawa, 2020. http://hdl.handle.net/10393/40464.

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As mankind attempts to halt climate change and global warming, large-scale carbon dioxide (CO2) capture, utilization and storage (CCUS) technologies are viewed as an indispensable approach to curb CO2 emission. This thesis focused on better understanding CO2-amine interactions during adsorption, while developing in parallel covalently immobilized polyethylenimine (PEI) adsorbents for CO2 adsorption. In addition, catalyst reusability issues reported in the synthesis of cyclic carbonates (CCs) from CO2 and epoxides using metal-free supported immobilized quaternary ammonium salts are addressed, while developing new organosilicas for the synthesis of CCs. The reaction between CO2 and amine was investigated at the gas-solid interface in an attempt to provide a unified CO2-amine interaction both in adsorption and absorption. A combination of density functional theory calculations and experimental data (FTIR and 13C NMR) showed that the formation of the zwitterion intermediate often reported in the literature is highly unlikely, instead a six-atom centered zwitterion mechanism involving the “assisting” effect of water, amine or other functional groups was found to be more feasible due to its lower activation energy. Moreover, evidence was provided to suggest that under humid conditions, bicarbonate and carbonate are formed from the reaction between water and CO2, and not the widely reported carbamate hydrolysis. With a goal of minimizing the leaching of amines on PEI-impregnated adsorbents, PEI was covalently immobilized on mesoporous aluminosilica using 3-glycidoxypropyltrimethoxysilane or 3-triethoxysilylpropyl isocyanate as linkers. The resultant materials were found to be more resistant to leaching (in ethanol) and degradation (air at 100 oC) compared to their impregnated counterparts. Further enhancement in oxidation stability was achieved by covalently grafting epoxide-functionalized PEI onto mesoporous aluminosilica. CO2 uptake over amine-containing adsorbents is widely reported to be enhanced in the presence of moisture. However, the same cannot be said for other adsorbents, such as, carbonaceous and zeolite-based materials, and most MOFs. In a soon to be submitted review manuscript, a comprehensive analysis on the role of water on CO2 uptake (equilibrium and kinetics), material structure and regeneration over a wide range of adsorbents is presented. As for CO2-epoxides fixation to cyclic carbonates, a quaternary ammonium salt supported on SBA-15 was used to investigate the observed literature trend between product yield and substrate type with catalyst reuse. Under mild reaction conditions (1.0 MPa CO2, 100 oC and 4 h), 1,2-butylene carbonate was obtained in high yields (> 95%) over 5 cycles as the substrate is easy to activate and the product can be completely removed from the catalyst surface due to its low boiling point. Nonetheless, using styrene oxide led to decrease in yield over reuse cycles, mainly because styrene carbonate crystals were trapped on the catalysts surface (13C MAS NMR and TGA data), thereby blocking access to active sites. By extensively washing all spent catalysts in acetone and using chromatographic grade SiO2 as support material, styrene carbonate was obtained in very good yield (> 93%) over five cycles. Finally, novel quaternary ammonium iodide-based organosilicas, grouped into disordered, ordered and periodic mesoporous organosilicas, were prepared and tested for the cycloaddition of CO2 to epoxide to yield cyclic carbonates. Under mild reaction conditions (0.5 MPa CO2, 50 oC and 10 – 15 h) catalysts with the ordered mesoporous organosilicas structure were found to be more active owing to their larger surface area and pore volume, enhancing the accessibility of active sites by epoxides.

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Errey, Olivia Claire. « Variable capture levels of carbon dioxide from natural gas combined cycle power plant with integrated post-combustion capture in low carbon electricity markets ». Thesis, University of Edinburgh, 2018. http://hdl.handle.net/1842/33240.

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This work considers the value of flexible power provision from natural gas-fired combined cycle (NGCC) power plants operating post-combustion carbon dioxide (CO2) capture in low carbon electricity markets. Specifically, the work assesses the value of the flexibility gained by varying CO2 capture levels, thus the specific energy penalty of capture and the resultant power plant net electricity export. The potential value of this flexible operation is quantified under different electricity market scenarios, given the corresponding variations in electricity export and CO2 emissions. A quantified assessment of natural gas-fired power plant integrated with amine-based post-combustion capture and compression is attempted through the development of an Aspen Plus simulation. To enable evaluation of flexible operation, the simulation was developed with the facility to model off-design behaviour in the steam cycle, amine capture unit and CO2 compression train. The simulation is ultimately used to determine relationships between CO2 capture level and the total specific electricity output penalty (EOP) of capture for different plant configurations. Based on this relationship, a novel methodology for maximising net plant income by optimising the operating capture level is proposed and evaluated. This methodology provides an optimisation approach for power plant operators given electricity market stimuli, namely electricity prices, fuel prices, and carbon reduction incentives. The techno-economic implications of capture level optimisation are considered in three different low carbon electricity market case studies; 1) a CO2 price operating in parallel to wholesale electricity selling prices, 2) a proportional subsidy for low carbon electricity considered to be the fraction of plant electrical output equal to the capture level, and 3) a subsidy for low carbon electricity based upon a counterfactual for net plant CO2 emissions (similar to typical approaches for implementing an Emissions Performance Standard). The incentives for variable capture levels are assessed in each market study, with the value of optimum capture level operation quantified for both plant operators and to the wider electricity market. All market case studies indicate that variable capture is likely to increase plant revenue throughout the range of market prices considered. Different market approaches, however, lead to different valuation of flexible power provision and therefore different operating outcomes.

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Ystad, Paul Andreas Marchioro. « Power Plant with CO2 Capture based on Absorption : Integration Study ». Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for energi- og prosessteknikk, 2010. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-11057.

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This thesis gives a detailed evaluation of the integration of power plants and post-combustion CO2 capture based on absorption. The study looks at natural gas combined cycles and pulverized coal power plants. Also the absorption process has been evaluated separately, aiming at reducing energy requirements in the capture process. In the first part of the thesis a theoretical part was given on fundamentals of CO2 capture by absorption, power generation, and process integration. Based on this theory, several case studies were defined for each of the three main processes. Simulation models were built accordingly and investigated. Simulation results from the capture process showed that there was a reboiler energy saving potential of 29% and 27% for NGCC and PC plant, respectively, when including vapor compression and absorption intercooling in the capture process. Another interesting observation made was reduced cooling duty in the overhead condenser of the stripper when applying vapor compression.Analysis of steam extraction from the NGCC plant showed it was possible to cover 1 MJ/kg CO2 directly from the HRSG. This steam can be provided directly from the LPB. For duties above 1 MJ/kg CO2 a secondary extraction point was required. In this study the IP/LP crossover was considered the most appropriate point to extract the remaining steam. The efficiency penalty when integrated with the different CO2 capture cases ranged from 7-8%, giving a net plant efficiency of 49.6-50.5%. At part load it was shown that the LPT should be throttled in order to secure constant pressure at the extraction point.For the PC plant the feedwater heat system showed potential in terms heat recovery in the return stream from the capture process. By integrating the return stream with FWH2, energy savings of 11.9% compared to the base case plant were found. Also it was found that the IP/LP crossover pressure should be set to 4.5 bar, since the IPT has the highest efficiency and therefore power production in this unit should be maximized. The final results for the PC plant efficiency range from 30-31.7% and the percentual efficiency penalty was 10-11.7% for the four capture case studies. As was the case for the NGCC plant, the LPT should be throttled when operating at part load.

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Leifsen, Henning. « Post-Combustion CO2 Capture Using Chemical Absorption : Minimizing Energy Requirement ». Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for energi- og prosessteknikk, 2007. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-12865.

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Capture and storage from fossil fuel fired power plants is drawing increasing interest as a potential method for the control of greenhouse gas emissions. An optimization and technical parameter study for a CO2 capture process of the flue gas of a commercial gas power plant, based on absorption/desorption process with MEA solutions, using HYSYS with the Amine Property Package fluid package, has been performed. The optimization has aimed to reduce the energy requirement for solvent regeneration, by investigating the effects of circulation rate, cross-flow heat exchanger minimum approach, desorber operating pressure and the absorber diameter. In addition, an economic evaluation including investment cost has been performed for the first three parameters.Major energy savings can be realized by optimizing the desorber pressure and the solvent circulation rate. The circulation rate will have a clearly defined optimal point, while for the desorber pressure the temperature will be a limiting factor. A too high temperature may lead to amine degradation and corrosion problems. The cross-flow heat exchanger minimum temperature approach will not affect the energy consumption significantly. An optimum absorber column diameter was not found, but the column should be designed with a diameter large enough to prevent flooding through the column. A too large diameter will not favour the energy consumption very much, and other factors will be more decisive when the column diameter is chosen.

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Johnsen, Erik Lien. « Optimization based design of an IRCC process with CO2 capture ». Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for industriell økonomi og teknologiledelse, 2011. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-15070.

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To deal with the threat of climate change, many technologies should be investigated, and power generation through an IRCC with CO2 capture is one alternative. However, capturing CO2 has a negative effect on the efficiency of the process as it requires a lot of energy. In this work, we try to reduce the energy consumption of an IRCC process with CO2 capture by developing a tool for finding the optimal process design with extensive heat integration.The design of an IRCC process involves many parameters which interfere in complex relationships. In this report, an MINLP model is established for optimizing important parameters simultaneously. The model relies on metamodeling based on process simulations in Aspen HYSYS to approximate difficult correlations, combined with a more direct approach for modeling computationally easier parts of the process.A general model for heat recovery targeting is developed for the heat integration optimization, and implemented as a part of the full IRCC optimization model.The global solver BARON is used for solving the problem, together with a relaxation procedure based on pinch analysis insights, and optimal solutions are usually found within several hours.The optimized IRCC process reaches a net electric efficiency of 49.97 %, assuming maximum heat integration, with only 1 % of the cooling and heating demands to be covered by utilities. The accuracy of the model is relatively good when compared to process simulations, but a less idealistic version of the IRCC should be designed based on the results to confirm the capability of the model.

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Rustenberg, Karin Hveding. « X-ray Studies of Capture, Storage and Release of CO2 ». Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for fysikk, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-18889.

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We show experimentally that CO2 intercalates into the interlayer spaceof the synthetic smectite clay Li-fluorohectorite (LiFh). The intercalationoccurs for a range of conditions in terms of pressure (5 bar to 20 bar) andtemperature (-20'C to 5'C). The mean basal spacing of the clay layersin LiFh intercalated by CO2 is found to be approximately 12.0 Å.We observe that the dynamics depends on the pressure, with a higherintercalation rate at increased pressure. Even under pressure of 20 bar,intercalation of CO2 is slower than H2O intercalation in fluorohectoritesby orders of magnitude.In situ observations show that LiFh is able to retain CO2 in the interlayerspace at room temperature, and the CO2 only starts leaving the clay attemperatures exceeding 30'C. Hydrated and CO2-intercalated clays areindistinguishable by use of X-ray diffraction alone. The difference in behaviorat higher temperatures is used as an additional confirmation thatintercalation of residual water is not the cause of the observed swelling.Furthermore, we report a new intercalation state corresponding to intercalationof more than one layer of CO2 into the interlamellar space, andhave also observed changes in the intercalation state of a monohydratedLiFh sample under exposure to CO2.We believe that the findings, concerning both intercalation and deintercalation,could be relevant for application of clays related to capture, transportor storage of CO2.

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Symonds, Robert. « Development of a Continuous Calcium Looping Process for CO2 Capture ». Thesis, Université d'Ottawa / University of Ottawa, 2017. http://hdl.handle.net/10393/36454.

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Carbon capture and storage technologies are required in order to reduce greenhouse gas emissions, while continuing to utilize existing fossil-fueled power generation stations. Of the many developing post-combustion CO2 capture technologies, calcium looping appears promising due to its high thermal efficiency, technical feasibility at commercial-scale, and low sorbent cost. Calcium looping has now been performed at the larger-scale, but there is still a significant quantity of information about sorbent performance, the fate of trace pollutant emissions (specifically SO2 and HCl), dual fluidized bed operating configurations, and impact of realistic operating conditions that still needs to be determined. Based on an economic analysis of the process, three key parameters serve to have the largest potential economic impact: (1) the sorbent deactivation rate, (2) the Ca/C molar ratio, and (3) the rate of sorbent attrition. Therefore, a series of bench-scale, pilot-scale, and continuous pilot-scale testing were conducted to not only explore these parameters from an improvement standpoint, but accurately determine them under conditions expected at the commercial-scale. The presence of HCl did not have a significant impact on sorbent performance provided that steam is present during calcination, although issues with downstream corrosion could be a factor. High CO2 partial pressures during calcination, coupled with high temperatures and the presence of SO2, resulted in dramatically lower cyclic carbonation conversions and a reduced high CO2 capture efficiency regime. Continuous pilot-scale testing generated realistic, and more detrimental, values for sorbent carrying capacity, Ca/C molar ratio, sorbent make-up rates, and rate of sorbent elutriation, that can now be utilized for techno-economic evaluations and scale-up of the technology.

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Wangen, Dan Jakob. « Life Cycle Assessment of Power Generation Technologies with CO2 Capture ». Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for energi- og prosessteknikk, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-19393.

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Carbon Capture and Storage has large a potential to mitigating the CO2 emissions caused by fossil fuel powered power plants. CCS reduces the energy efficiency of the plant and increases the demand on chemicals and infrastructure. It is though not only the direct emissions from the power plants that have an impact on the environment. The entire supply chain of the power plant has an impact, and it is therefore necessary to evaluate the entire life cycle of the plant. This thesis consists of a full process LCA of post-combustion absorption based carbon capture and storage (CCS) technologies for both coal power plants and natural gas power plants. The assessed CCS technologies are based on the solvents MEA, MDEA and chilled ammonia. MEA is the most commonly used solvent in post-combustion capture, while MDEA and chilled ammonia represents novel CCS technologies that are still under development. It was shown that a 90% capture rate was possible for all of the assessed capture technologies. It was further shown that the total global warming potential (GWP) could be decreased with above 60%. 90% reduction is not possible because of indirect emissions in the supply chain. The reduction in GWP comes at a cost of decreasing energy efficiency, which further leads to an increase in consumption of materials and infrastructure. This causes the non-GHG related impacts to increase, compared to a base scenario without CCS. CCS technology based on MDEA was calculated to be the technology with the lowest impact, mainly because it has the lowest energy requirement. Chilled ammonia was assessed as the technology with the largest impacts. The reason for this is that the chilling process is very energy intensive and therefore decreases the efficiency more, compared to the other technologies assessed. Also the large emissions of ammonia have a large impact on the acidification potential and the marine eutrophication potential.

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Llorente, Manso Ricardo. « CO2 capture in power plants- using the oxy-combustion principle ». Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for energi- og prosessteknikk, 2013. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-22791.

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In the CO2 capture from power generation, the energy penalties for the capture are one of the main challenges. Nowadays, the post-combustion methods have energy penalties lower than the oxy-combustion and pre-combustion technologies. One of the main disadvantages of the post-combustion method is the fact that the capture of CO2 at atmospheric pressure requires quite big equipment for the high flow rates of flue gas, and the low partial pressure of the CO2 generates an important loss of energy.The Allam cycle presented for NETPOWER gives high efficiencies in the power production and low energy penalties. A simulation of this cycle is made together with a simulation of power plants with pre-combustion and post-combustion capture and without capture for natural gas and for coal.The simulations give lower efficiencies than the proposed for NETPOWER. For natural gas the efficiency is 52% instead of the 59% presented, and 33% instead of 51% in the case of using coal as fuel. Are brought to light problems in the CO2 compressor due the high flow of CO2 that is compressed until 300bar to be recycled into the combustor.

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Skinnemoen, Maria Magnussen. « Process Simulation of Oxy-combustion CO2 Capture in Cement Plant ». Thesis, Norges Teknisk-Naturvitenskapelige Universitet, Institutt for elkraftteknikk, 2014. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-27337.

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The objectives of this master thesis have been to model and simulate oxy-combustion CO2 capture in a cement plant. The model developed is a process simulation of the calcination process with varying degree of air in-leakage, where heat is supplied by combustion in an oxygen rich environment, followed by capture of the CO2. The further gas separation after H2O condensation to achieve the required CO2 quality was evaluated. In addition to the process simulations, a review of literature related to oxy-combustion CO2 capture and cement production was performed, and an engineering evaluation of the necessary modifications to the cement plant conducted.A simulation model was built in Aspen HYSYS, and student Jelmer de Winter’s project work was utilized as a starting point. The model was developed with the aim to achieve results comparable to a process model constructed by the European Cement Research Academy (ECRA) in 2009. The goal was to capture as much of the CO2 as possible, and to achieve a CO2 purity of minimum 95 mol-% after the CO2 Compression and Purification Unit (CPU).CO2 purity in the dry flue gas of ~85 mol % was achieved, with a CO2 capture rate up to 96.4 %. Five different air in-leakages (2, 4, 6, 8 and 10 % of total flue gas flow) were tested. The results showed that the CO2 concentration in the flue gas decreased with increasing degree of air in-leakage. The decrease in CO2 concentration causes an increase of the power consumption of the CO2 CPU of ~2.6 % per percentage point of air in-leakage, and the CO2 capture rate was also reduced when the air in-leakage increased. These results agree well with results from previous oxy-combustion studies, and show the importance of minimizing air in-leakages in the cement plant.If oxy-combustion capture is to be utilized at a cement plant, some process modifications and additional equipment is required. An Air Separation Unit (ASU) is needed to provide almost pure oxygen for the combustion process. A Compression and Purification Unit (CPU) is also required, in order achieve the necessary CO2 purity and transport conditions. When using oxy-combustion technology, both the material conversion in the cement kiln system and the operational specifications of the overall process are different from those in conventional kiln operation. However, research made by ECRA in 2012 showed that the negative impacts of oxy-combustion on the product quality seem to be negligible.Other necessary process modifications when retrofitting with oxy-combustion are news design of the kiln burner and the clinker cooler in the cement plant. In addition, prevention of excessive air in-leakage by improving sealing locations at the cement plant is necessary, as the simulation results show. This is possible e.g. by waste gas flushed systems, or by an improved maintenance of inspection doors and similar devices. The CPU is up to a certain point capable of handling changes in the flue gas composition at short-term inspections; however it limits its efficiency.

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Thèses sur le sujet « CO2 capture and conversion »

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