Добірка наукової літератури з теми "CO2 capture and utilization"

Closing the anthropogenic carbon cycle is one important strategy to combat climate change, and requires the chemistry to effectively combine CO2 capture with its conversion. Here, we propose a novel in situ CO2 utilization concept, calcium-looping reforming of methane, to realize the capture and conversion of CO2 in one integrated chemical process. This process couples the calcium-looping CO2 capture and the CH4 dry reforming reactions in the CaO-Ni bifunctional sorbent-catalyst, where the CO2 captured by CaO is reduced in situ by CH4 to CO, a reaction catalyzed by catalyzed by the adjacent metallic Ni. The process coupling scheme exhibits excellent decarbonation kinetics by exploiting Le Chatelier’s principle to shift reaction equilibrium through continuous conversion of CO2, and results in an energy consumption 22% lower than that of conventional CH4 dry reforming for CO2 utilization. The proposed CO2 utilization concept offers a promising option to recycle carbon directly at large CO2 stationary sources in an energy-efficient manner.

Summary Recent progress in carbon capture, utilization, and storage (CCUS) is reviewed. Considerable research effort has gone into carbon dioxide (CO2) capture, with many promising separation processes in various stages of development, but only a few have been tested at commercial scale, and considerable additional development will be required to determine competitiveness of new technologies. Processes for direct capture of CO2 from the air are also under development and are starting to be tested at pilot scale. Transportation of CO2 to storage sites by pipeline is well-established, though substantially more pipeline capacity will be required if CCUS is to be undertaken at a large scale. Considerable experience has now been built up in enhanced-oil-recovery (EOR) operations, which have been under way since the 1970s. Storage in deep saline aquifers has also been achieved at scale. Recent large-scale projects that capture and store CO2 are described, as are current and potential future markets for CO2. Potential effects of changes in the US tax code Section 45Q on those markets are summarized. Future deployment of CCUS will depend more on cost reductions for CO2 separations, development of new markets for CO2, and the complexities of project finance than on technical issues associated with storage of CO2 in the subsurface.

Carbon dioxide CO2 is a component of air that is responsible for the growing global warning and greenhouse gases emissions. The energy sector is one of the main sources of CO2 emissions in the world and especially in Ukraine. Carbon capture, utilization and storage (CCUS) is a group of technologies that play a significant role along with renewable energy sources, bioenergy and hydrogen to reduce CO2 emissions and to achieve international climate goals. Nowadays there are thirty-five commercial CCUS facilities under operation around the world with a CO2 capture capacity up to 45 million tons annually. Tougher climate targets and increased investment provide new incentives for CCUS technologies to be applied more widely. CCUS are applications in which CO2 is captured from anthropogenic sources (power generation and industrial processes) and stored in deep geological formations without entering atmosphere or used in various products using technologies without chemical modification or with conversion. The article discusses the use of various technologies of CO2 capture (post-combustion capture, pre-combustion capture and oxy-combustion capture), CO2 separation methods and their application in the global energy transition to reduce the carbon capacity of energy systems. Technical and economic indicators of CO2 capture at different efficiencies for coal and gas power plants are given. Technologies of transportation and storage of captured carbon dioxide and their economic indicators are considered. The directions for the alternative uses of captured CO2, among which the main ones are the production of synthetic fuels, various chemicals and building materials, are also presented and described in the paper. The possibility of utilization captured СО2 in the production of synthetic fuel in combination with Power-to-Gas technologies was studied. Keywords: greenhouse gases emissions, fossil fuels, СО2 capture technologies, capture efficiency, synthetic fuel

Global fossil fuel consumption has induced emissions of anthropogenic carbon dioxide (CO2), which has emanated global warming. Significant levels of CO2 are released continually into the atmosphere from the extraction of fossil fuels to their processing and combustion for heat and power generation including the fugitive emissions from industries and unmanaged waste management practices such as open burning of solid wastes. With an increase in the global population and the subsequent rise in energy demands and waste generation, the rate of CO2 release is at a much faster rate than its recycling through photosynthesis or fixation, which increases its net accumulation in the atmosphere. A large amount of CO2 is emitted into the atmosphere from various sources such as the combustion of fossil fuels in power plants, vehicles and manufacturing industries. Thus, carbon capture plays a key role in the race to achieve net zero emissions, paving a path for a decarbonized economy. To reduce the carbon footprints from industrial practices and vehicular emissions and attempt to mitigate the effects of global warming, several CO2 capturing and valorization technologies have become increasingly important. Hence, this article gives a statistical and geographical overview of CO2 and other greenhouse gas emissions based on source and sector. The review also describes different mechanisms involved in the capture and utilization of CO2 such as pre-combustion, post-combustion, oxy-fuels technologies, direct air capture, chemical looping combustion and gasification, ionic liquids, biological CO2 fixation and geological CO2 capture. The article also discusses the utilization of captured CO2 for value-added products such as clean energy, chemicals and materials (carbonates and polycarbonates and supercritical fluids). This article also highlights certain global industries involved in progressing some promising CO2 capture and utilization techniques.

Major fossil fuel consumption associated with CO2 emission and socioeconomic instability has received much concern within the global community regarding the long-term sustainability and security of these commodities. The capture, sequestration, and conversion of CO2 emissions from flue gas are now becoming familiar worldwide. Nanostructured carbonaceous materials with designed functionality have been extensively used in some key CO2 exploitation processes and techniques, because of their excellent electrical conductivity, chemical/mechanical stability, adjustable chemical compositions, and abundant active sites. This review focuses on a variety of carbonaceous materials, like graphene, carbon nanotubes, amorphous porous carbons and carbon hybrid composites, which have been demonstrated promising in CO2 capture/separation and conversion (electrocatalysis and photocatalysis) to produce value-added chemicals and fuels. Along with the discussion and concerning synthesis strategies, characterization and conversion and capture/separation techniques employed, we further elaborate the structure-performance relationships in terms of elucidating active sites, reaction mechanisms and kinetics improvement. Finally, challenges and future perspectives of these carbon-based materials for CO2 applications using well-structured carbons are remarked in detail.

The paper presents and discusses modern methods and technologies of CO2 capture (pre-combustion capture, post-combustion capture, and oxy-combustion capture) along with the principles of these methods and examples of existing and operating installations. The primary differences of the selected methods and technologies, with the possibility to apply them in new low-emission energy technologies, were presented. The following CO2 capture methods: pre-combustion, post-combustion based on chemical absorption, physical separation, membrane separation, chemical looping combustion, calcium looping process, and oxy-combustion are discussed in the paper. Large-scale carbon capture utilization and storage (CCUS) facilities operating and under development are summarized. In 2021, 27 commercial CCUS facilities are currently under operation with a capture capacity of up to 40 Mt of CO2 per year. If all projects are launched, the global CO2 capture potential can be more than ca. 130–150 Mt/year of captured CO2. The most popular and developed indicators for comparing and assessing CO2 emission, capture, avoiding, and cost connected with avoiding CO2 emissions are also presented and described in the paper.

The carbon dioxide (CO2) is notorious as the greenhouse gas, which could cause the global warming and climate change. Therefore, the reduction of the atmospheric CO2 emissions from power plants and other industrial facilities has become as an increasingly urgent concern. In the recent years, CO2 capture and storage technologies have received a worldwide attention. Adsorption is considered as one of the efficient options for CO2 capture because of its cost advantage, low energy requirement and extensive applicability over a relatively wide range of temperature and pressure. The metal organic frameworks (MOFs) show widely potential application prospects in CO2 capture and storage owing to their outstanding textural properties, such as the extraordinarily high specific surface area, tunable pore size, ultrahigh porosity (up to 90%), high crystallinity, adjustable internal surface properties, and controllable structure. Herein, the most important research progress of MOFs materials on the CO2 capture and storage in recent years has been comprehensively reviewed. The extraordinary characteristics and CO2 capture performance of Zeolitic Imidazolate Frameworks (ZIFs), Bio-metal organic frameworks (bio-MOFs), IL@MOFs and MOF-composite materials were highlighted. The promising strategies for improving the CO2 adsorption properties of MOFs materials, especially the low-pressure adsorption performance under actual flue gas conditions, are also carefully summarized. Besides, CO2 is considered as an abundant, nontoxic, nonflammable, and renewable C1 resource for the synthesis of useful chemicals and fuels. The potential routes for resource utilization of the captured CO2 are briefly proposed.

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.

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.

El continu increment en l'ús de les energies renovables i els objectius per a la reducció de les emissions de diòxid de carboni (CO2) requereixen canvis significatius tant a nivell tècnic com a nivell normatiu. La captura i utilització de diòxid de carboni (CCU, per les sigles en anglès) és un mètode eficaç per aconseguir la mitigació del CO2 i al mateix temps mantenir de forma segura els subministraments d'energia. Si bé la demanda a la reducció de les emissions de CO2 està augmentant, l'eficiència energètica i el cost dels processos de captura de CO2 segueixen sent un factor limitant per a les aplicacions industrials. En el present treball s'estudia l'ús del procés d'adsorció per oscil·lació de pressió i buit (VPSA, per les sigles en anglès) amb adsorbents d'alta selectivitat per separar el CO2 dels gasos de combustió, com un mètode alternatiu al procés d'absorció tradicional amb amines. Es realitza un estudi preliminar mitjançant Anàlisi Tèrmica per determinar la capacitat d’adsorció i el comportament cíclic de la captura de CO2 per deu adsorbents comercials, inclosos els tamisos moleculars de carboni (CMS) i les zeolites. L'anàlisi es va fer amb CO2 pur, N2 pur i mescles dels dos gasos en la proporció 15%/85% que correspon a la composició d’un gas de combustió normal; s’usen les zeolites comercials 13X, 5A, 4A sense i amb aglomerants i tres tamisos moleculars de carboni (CMS) en l’interval de pressió de 0 a 10 bar i a 283K, 298K, 232K i 323 K de temperatura. Els resultats s’han ajustat amb els models Toth, Sips i Dual Site Langmuir (DSL). Es va realitzar una selecció entre deu adsorbents comercials per a la captura de CO2, inclosos els tamisos moleculars de carbó (CMS, per les sigles en anglès) i les zeolites. Es van determinar les propietats texturals, la capacitat d'adsorció i el comportament cíclic dels adsorbents per comparar el seu comportament a la separació del diòxid de carboni del nitrogen. Posteriorment, es van mesurar les isotermes d'adsorció d'un sol component en la balança de suspensió magnètica a quatre temperatures diferents (283, 298, 232 i 323 K) i en un ampli marge de pressions (de 0 a 10 bara). Les dades sobre les isotermes de components purs es van correlacionar utilitzant els models Toth, Sips i Dual Site Langmuir (DSL). Es van dissenyar i construir tres unitats de laboratori per realitzar l'experimentació del procés VPSA. La primera unitat es va usar per a la producció i el control de mescles gasoses de CO2 i N2 a una pressió màxima de 9 bara. En la segona unitat es van dur a terme la determinació dels equilibris d'adsorció amb una barreja de composició semblant a la dels gasos de combustió (15/85% de CO2/N2 v/v). Amb el programa Aspen Adsorption® es va simular el sistema experimental, obtenint que les prediccions del model DSL reprodueixen suficientment bé els resultats experimentals de les corbes de ruptura i els perfils de temperatura en el llit fix. A més, es van fer estudis dinàmics per avaluar les zeolites 5ABL i 13XBL usant el procés VPSA discontinu per a la separació CO2 de N2. La unitat dos es va dotar d'un sistema de control amb una interfície PLC que facilita la seva operació i automatització, usant una estratègia de control desenvolupada en aquest treball. En base als resultats obtinguts amb la unitat dos, tant experimentals com simulats, es va trobar que la zeolita 13XBL era la més adequada per al procés VPSA proposat. Els resultats experimentals es van emprar per alimentar el disseny de la unitat dos a Aspen Adsorption® i validar el model usat que al seu torn es va utilitzar per realitzar un disseny complet d'experiències de dos factors (26) en configuració continua. La tercera unitat experimental consta de tres columnes d'adsorció on es va incloure l'estratègia de control desenvolupada per la unitat dos i es va incloure la recirculació dels corrents rics en N2 i CO2. Es van dur a terme tres experiments del procés VPSA cíclic de 8 passos canviant els paràmetres de control del procés automatitzat i usant la zeolita 13XBL com adsorbent. Es va aconseguir satisfer els objectius en termes puresa de CO2 (> 80%) i consum energètic (<2.5 kWh/kgCO2). Sobre la base dels resultats experimentals i simulats, es va realitzar una demostració a escala pilot de la captura de CO2 del gas de combustió d'una caldera de vapor en una planta industrial a situada a la província de Barcelona.La planta pilot de captura de CO2 consta d'un procés de pretractament dels gasos de combustió, una unitat VPSA acoblada amb una unitat de deshumidificació i una aplicació industrial per a l'ús del CO2. A la unitat de pretractament, els gasos de combustió es van refredar de 70ºC a 25ºC i es van desnitrificar. A la unitat de deshumidificació, es va eliminar el vapor d'aigua del gas desnitrificat mitjançant adsorció sobre alúmina. Posteriorment, es va emprar el procés VPSA de vuit passos amb tres columnes usant zeolita 13XBL, en la qual es va obtenir un corrent enriquit de CO2 de 85 a 95% de puresa de CO2, amb una recuperació del 48 a 56%, una productivitat de 0,20-0,25 gCO2/(gads·h) i un consum energètic de 1.48 kWh/kgCO2. El CO2 recuperat es va usar per reemplaçar l'ús d'àcids minerals en l'etapa de regulació del pH de la planta de tractament d'aigües residuals existent a la fàbrica. Per tant, el procés desenvolupat és una alternativa efectiva per separar el CO2 dels punts d'emissió de gasos de combustió industrial i utilitzar el CO2 recuperat com a matèria primera per a aplicacions industrials. L'ús de CO2 capturat en aquestes fonts d'emissió té dos avantatges clars. D'una banda, es van reduir les emissions de CO2 a la atmosfera. De l'altra, va permetre reutilitzar i transformar un contaminant ambiental en compostos neutres.
El continuo incremento en el uso de las energías renovables y los objetivos para la reducción de las emisiones de dióxido de carbono (CO2) requieren cambios significativos tanto a nivel técnico como a nivel normativo. La captura y utilización de dióxido de carbono (CCU, por sus siglas en inglés) es un método eficaz para lograr la mitigación del CO2 y al mismo tiempo mantener de forma segura los suministros de energía. Si bien la demanda en la reducción de las emisiones de CO2 está aumentando, la eficiencia energética y el costo de los procesos de captura de CO2 siguen siendo un factor limitante para las aplicaciones industriales. En el presente trabajo se estudia el uso del proceso de adsorción por oscilación de presión y vacío (VPSA, por sus siglas en inglés) con adsorbentes de alta selectividad para separar el CO2 de los gases de combustión, como un método alternativo al proceso de absorción tradicional con aminas. Se realizó una selección entre diez adsorbentes comerciales para la captura de CO2, incluidos los tamices moleculares de carbón (CMS, por sus siglas en inglés) y las zeolitas. Se determinaron las propiedades texturales, la capacidad de adsorción y el comportamiento cíclico de los adsorbentes para comparar su comportamiento en la separación del dióxido de carbono del nitrógeno. Posteriormente, se midieron las isotermas de adsorción de un solo componente en la balanza de suspensión magnética a cuatro temperaturas diferentes (283, 298, 232 y 323 K) y en un amplio margen de presiones (de 0 a 10 bara). Los datos sobre las isotermas de componentes puros se correlacionaron utilizando los modelos Toth, Sips y Dual Site Langmuir (DSL). Se diseñaron y construyeron tres unidades de laboratorio para realizar la experimentación del proceso VPSA. La primera unidad se usó para la producción y el control de mezclas gaseosas de CO2 y N2 a una presión máxima de 9 bara. En la segunda unidad se llevaron a cabo las mediciones de los equilibrios de adsorción con una mezcla de composición semejante a la de los gases de combustión (15/85% de CO2/N2 v/v). Con el programa Aspen Adsorption® se simuló el sistema experimental, obteniendo que las predicciones del modelo DSL reproducen suficientemente bien los resultados experimentales de las curvas de ruptura y los perfiles de temperatura en el lecho fijo. Además, se hicieron estudios dinámicos para evaluar las zeolitas 5ABL y 13XBL usando el proceso VPSA discontinuo para la separación CO2 de N2. La unidad dos se dotó de un sistema de control con una interfaz PLC que facilita su operación y automatización, usando una estrategia de control desarrollada en este trabajo. En base a los resultados obtenidos con la unidad dos y su simulación, se encontró que la zeolita 13XBL era la que la más adecuada para el proceso VPSA propuesto. Los resultados experimentales se usaron para alimentar el diseño de la unidad dos en Aspen Adsorption® y validar el modelo usado que a su vez se utilizó para realizar un diseño completo de experiencias de dos factores (26) en configuración discontinua. La tercera unidad experimental consta de tres columnas de adsorción donde se incluyó la estrategia de control desarrollada para la unidad dos y se incluyó la recirculación de las corrientes ricas en N2 y CO2. Se llevaron a cabo tres experimentos en el proceso VPSA cíclico de 8 pasos cambiando los parámetros de control del proceso automatizado y usando la zeolita 13XBL como adsorbente. Se logró satisfacer los objetivos en términos pureza de CO2 (>80%) y consumo energético (<2.5 kW·h/kgCO2). Sobre la base de los resultados experimentales y simulados, se realizó una demostración a escala piloto de la captura de CO2 del gas de combustión de una caldera de vapor en una planta industrial situada en la provincia de Barcelona. La planta piloto de captura de CO2 consta de un proceso de pretratamiento de los gases de combustión, una unidad VPSA acoplada con una unidad de deshumidificación y una aplicación industrial para el uso del CO2. En la unidad de pretratamiento, los gases de combustión se enfriaron de 70ºC a 25ºC y desnitrificaron. En la unidad de deshumidificación, se eliminó el vapor de agua del gas desnitrificado mediante adsorción con alúmina. Posteriormente, se empleó el proceso VPSA de ocho pasos con tres columnas usando zeolita 13XBL, en la que se obtuvo una corriente enriquecida de CO2 de 85 a 95% de pureza de CO2, con una recuperación del 48 a 56%, una productividad de 0.20 a 0.25 gCO2/(gads٠h-) y un consumo energético de 1.48 kWh/ kgCO2. El CO2 recuperado se usó para reemplazar el uso de ácidos minerales en la etapa de regulación del pH de la planta de tratamiento de aguas residuales existente en la fábrica. Por lo tanto, el proceso desarrollado es una alternativa efectiva para separar el CO2 de los puntos de emisión de gases de combustión industrial y utilizar el CO2 recuperado como materia prima para aplicaciones industriales. El uso de CO2 capturado en estas fuentes de emisión tiene dos ventajas claras. Por un lado, redujeron las emisiones de CO2 a la atmósfera. Por otro lado, permitió reutilizar y transformar un contaminante ambiental en compuestos neutros.
The continuously increasing share of renewable energy sources and European Union targets for carbon dioxide (CO2) emission reduction need significant changes both on a technical and regulatory level. Carbon dioxide capture and utilization (CCU) is an effective method for achieving CO2 mitigation while simultaneously keeping energy supplies secure. While the demand for reduction in CO2 emissions is increasing, the improvement of energy-efficiency and the cost of CO2 capture processes remains a limiting factor for industrial applications. The present work studies the Vacuum Pressure Swing Adsorption process (VPSA) using high selectivity adsorbents for separating CO2 from flue gas as an alternative method to the traditional absorption process with amines. A screening analysis for CO2 capture was conducted on ten commercial adsorbents, including carbon molecular sieves (CMS) and zeolites. The textural properties, the adsorption capacities and the adsorbent cyclic behaviors were determined to compare their performance in the context of CO2 separation from nitrogen (N2). Subsequently, the single component adsorption isotherms were measured in a magnetic suspension balance at four different temperatures (283, 298, 232 and 323 K) and over a large range of pressures (from 0 to 10 bara). Data on the pure component isotherms were correlated using the Toth, Sips and Dual Site Langmuir (DSL) models. Three laboratory units were designed and built to perform the VPSA experiments. The first was used for the production and control of CO2 and N2 gas mixtures at a maximum pressure of 9 bara. Adsorption equilibrium measurements with a mixture that resembles the composition of combustion gases (15/85% CO2/N2 v/v) were obtained using the second unit that was built. Afterwards, the Aspen Adsorption® program was used to simulate the experimental system, where the predictions of the DSL model agree with the breakthrough curves and the temperature profiles of the experimental fixed bed results. In addition, dynamic studies were performed to evaluate the zeolites 5ABL and 13XBL using a discontinuous VPSA process for the CO2 separation of N2. The process was automated and operated with a PLC interface, using a control strategy developed in this work. Based on the comparison results of the zeolites, it was found that the 13XBL zeolite was the one most suitable for the proposed VPSA process. The experimental results were verified by numerical simulations in the Aspen Adsorption® software and the validated model was used to perform a two-factor complete design of experiments (26) using 13XBL simulations in a discontinuous configuration. The third experimental unit was built with three adsorption columns which included the developed control strategy and the recirculation of N2 and CO2 rich streams. Three experiments were carried out using zeolite 13XBL as an adsorbent for the proposed 8-step VPSA cyclic process by changing the control parameters of the automated process. Through the experiments, the objectives were achieved in terms of CO2 purity (> 90%) and energy consumption (> 2.5 kWh/kgCO2). Based on the experimental and simulated results, a pilot-scale demonstration plant for CO2 capture from flue gas in an existing industrial boiler in a Spanish company was carried out. The pilot-scale CO2 capture plant consisted of a pre-treatment process for flue gases, a VPSA unit coupled with a dehumidification unit and an industrial application for the use of CO2. In the pretreatment unit the flue gases were cooled from 70°C to 25°C and then denitrified. In the dehumidification unit, the water vapor was removed from the denitrified gas by adsorption with alumina. Subsequently, the three columns’ eight-step VPSA process developed with zeolite 13XBL was used. The results were a product purity of 85 to 95% of CO2, a recovery of 48 to 56%, a productivity of 0.20 to 0.25 gCO2/(gads٠h) and an energy consumption of 1.48 kWh/kgCO2. The recovered CO2 was then used to replace the use of mineral acids in the pH regulation stage of the existing wastewater treatment plant. Therefore, it is concluded that the developed process is an effective alternative to separate the CO2 from the emission points of industrial combustion gases and to use the recovered CO2 as raw material for industrial applications. The use of CO2 captured in these emission sources has two clear advantages. On the one hand, it reduces the CO2 emissions to the atmosphere. On the other hand, it allows the reuse and transformation of an environmental pollutant into neutral compounds.

Carbon capture, utilization and storage (CCUS) in confined saline aquifers in sedimentary formations has the potential to reduce the impact of fossil fuel combustion on climate change by storing CO2 in geologic formations in perpetuity. At PT conditions relevant to CCUS, CO2 is less dense than the pre-existing brine in the formation, and the more buoyant CO2 will migrate to the top of the formation where it will be in contact with cap rock. A typical cap rock is clay-rich shale, and interactions between shales and CO2 are poorly understood at PT conditions appropriate for CCUS in saline formations. In this study, the interaction of CO2 with clay minerals in the cap rock overlying a saline formation has been examined, using Na-rich montmorillonite as an analog for clay-rich shale. Attenuated Total Reflectance -- Fourier Transform Infrared Spectroscopy (ATR -FTIR) was used to identify potential crystallographic sites (AlAlOH, AlMgOH and interlayer space) where CO2 could interact with montmorillonite at 35"C and 50"C and from 0-1200 psi.  Analysis of the data indicates that CO2 that is preferentially incorporated into the interlayer space, with dehydrated montmorillonite capable of incorporating more CO2 than hydrated montmorillonite. No evidence of chemical interactions between CO2 and montmorillonite were identified, and no spectroscopic evidence for carbonate mineral formation was observed.  Further work is needed to determine if reservoir seal quality is more likely to be degraded or enhanced by CO2 - montmorillonite interactions.
Master of Science

The anthropogenic carbon dioxide (CO2) emission into the atmosphere, mainly through the combustion of fossil fuels, has resulted in a balance disturbance of the carbon cycle. Overwhelming scientific evidence proves that the escalating level of atmospheric CO2 is deemed as the main culprit for global warming and climate change. It is thus imperative to develop viable CO2 capture and sequestration (CCS) technologies to reduce CO2 emissions, which is also essential to avoid the potential devastating effects in future. The drawbacks of energy-cost, corrosion and inefficiency for amine-based wet-scrubbing systems which are currently used in industry, have prompted the exploration of alternative approaches for CCS. Extensive efforts have been dedicated to the development of functional porous materials, such as activated carbons, zeolites, porous organic polymers, and metal-organic frameworks (MOFs) to capture CO2. However, these adsorbents are limited by either poor selectivity for CO2 separation from gas mixtures or low CO2 adsorption capacity. Therefore, it is still highly demanding to design next-generation adsorbent materials fulfilling the requirements of high CO2 selectivity and enough CO2 capacity, as well as high water/moisture stability under practical conditions. Metal-organic frameworks (MOFs) have been positioned at the forefront of this area as a promising type of candidate amongst various porous materials. This is triggered by the modularity and functionality of pore size, pore walls and inner surface of MOFs by use of crystal engineering approaches. In this work, several effective strategies, such as incorporating 1,2,3-triazole groups as moderate Lewis base centers into MOFs and employing flexible azamacrocycle-based ligands to build MOFs, demonstrate to be promising ways to enhance CO2 uptake capacity and CO2 separation ability of porous MOFs. It is revealed through in-depth studies on counter-intuitive experimental observations that the local electric field favours more than the richness of exposed nitrogen atoms for the interactions between MOFs and CO2 molecules, which provides a new perspective for future design of new MOFs and other types of porous materials for CO2 capture. Meanwhile, to address the water/moisture stability issue of MOFs, remote stabilization of copper paddlewheel clusters is achieved by strengthening the bonding between organic ligands and triangular inorganic copper trimers, which in turn enhances the stability of the whole MOF network and provides a better understanding of the mechanism promoting prospective suitable MOFs with enhanced water stability. In contrast with CO2 capture by sorbent materials, the chemical transformation of the captured CO2 into value-added products represents an alternative which is attractive and sustainable, and has been of escalating interest. The nanospace within MOFs not only provides the inner porosity for CO2 capture, but also engenders accessible room for substrate molecules for catalytic purpose. It is demonstrated that high catalytic efficiency for chemical fixation of CO2 into cyclic carbonates under ambient conditions is achieved on MOF-based nanoreactors featuring a high-density of well-oriented Lewis active sites. Furthermore, described for the first time is that CO2 can be successfully inserted into aryl C-H bonds of a MOF to generate carboxylate groups. This proof-of-concept study contributes a different perspective to the current landscape of CO2 capture and transformation. In closing, the overarching goal of this work is not only to seek efficient MOF adsorbents for CO2 capture, but also to present a new yet attractive scenario of CO2 utilization on MOF platforms.

Accelerated carbonation is a new C02 storage method under development as a  solutionfor climatechangecausedbyanthropogenicactivities.Inacceleratedcarbonationanalkalinesourcesuch as minerals or industrial resid ues react with carbon dioxide in a presence of slightly acidicsolution to produce stable solid carbonates. There are varieties of accelerated carbonation routes,which differ in process condition. The aim of this study was to evaluate  and  compare  the potential of a slurry route process and a wet route process for the carbonation of basicoxygenfurnace slag using the C02 emitted by a conventional natural gas power plant. For this pmpose alife cycle assessment (LCA) study was performed based on principles and guidelines provided byISO 14040:2006 and routines and data provided by the SimaPro V8 software  package.Thematerial and energy requirements for each of the steps involved in the carbonation process, i.e.pre-treatment of raw material, C02 compression, transportation, carbonation step, after-treatmentand landfill, were calculated and included in the LCA study. The slurry and wet route resulted innet C02 reduction of 87.4% and 72.3% respectively. However, a positive contribution to otherenvironmental issues was observed with the wet route  leading to higher  impact mainly due  tohigh heating requirement. An exception was the contribution of the slurry route  to  abioticresource depletion, which was higher for the slurry route due to high water  requirement.  Ageneral conclusion was that the electricity consumption is the  main  cause  ofenvironmentalissues. Sensitivity analyses showed that the environmental impacts are dependent on thetransp01iation distance and electricity source, while no dependence was observed with respect toconstruction of the carbonation plant.

This thesis work contains an overview of potential alternative options to couple formate produced from CO2 with other coupling partners than formate itself. Ultimately, the intent is to produce high value chemicals from CO2 at a high selectivity and conversion, whilst keeping the required utility of electrons in the electrochemical CO2 conversion at a minimum. To select and find new coupling partners, a framework was developed upon which a broad variety of candidates were assessed and ranked. A multi-stage process was used to select first potential classes of molecules. For each class, a variety of commercially available compounds was analysed in depth for its potential suitability in the reaction with the active carbonite intermediate. This analysis has shown that a wide variety of factors come into play and especially the reactivity of the hydride catalyst poses a mayor challenge. The three major potential classes of compounds suitable for the coupling are carbon oxides (CO2 & CO), and aldehydes. As a second step the remaining options were ranked to identify which compound to test first. In this ranking the reactants sustainability, ease of commercial operation and commercial attractiveness of the compound were considered. The highest-ranking compounds that proposed the highest potential are CO2, benzaldehyde and para-formaldehyde. In proof-of-principle experiments CO2 could successfully be incorporated in the form of carbonate, oxalate and potentially formate. The overall incorporation efficiency based on the hydride consumption was shown to be 50%. It is suggested to continue this work with mechanistic studies to understand the reaction in detail as, based on further gained knowledge, the reaction can then be optimized towards optimal CO2 incorporation in the form of oxalate.

Carbon dioxide from biogas production is currently considered to be without value and isbecause of this released into the atmosphere in the biogas upgrading process. The residualgas is a potential carbon source and can create value in the biogas manufacturing process.By finding a suitable value-creating process that utilizes carbon dioxide, it can be possibleto provide both economic and environmental incentives for companies to develop theiroperations. This project explored the possibility to create value from this CO2. Through anevaluation of the technical maturity of CCU technologies, a recommendation could be givenat the end of the project. An analysis of technical barriers, such as pollutants in the gas, aswell as barriers in the form of competence and corporate culture were examined in orderto provide a reasoned recommendation. The project mapped which value-creating systemswould be suitable for biogas producers in a Swedish context. This included established methaneand carbon dioxide upgrading techniques currently in use and suitable CCU techniquesthat can interact with the selected upgrading processes and serve as value creators. Based onthis survey, it was then possible to identify common, critical variables for these systems. Thereafter,a recommendation of an appropriate CCU technology could be given depending onthe CO2 composition produced. One conclusion from the study was that carbon dioxide concentrationsfrom the residual gas was often high (approx. 97-98 %) and did not contain anycorrosive or toxic components, and that this largely depends on how the digestion reactor ishandled in the production process. Thus, questions were raised about what the actual limitationsof the CCU are, as they did not seem to be technical. CCU techniques that proved to beof particular interest were pH regulation of sewage plants, CO2 as a nutrient substrate for thecultivation of microalgae, and manufacturing of dry-ice for refrigerated transports. All of thesetechnologies currently have a sufficiently high degree of technical maturity to be installedalready today. Other CCU techniques, such as "’Power to gas”, require a high CO2 concentrationand were discarded as the literature review did not suggest the economic potential forthem as they require additional CO2 upgrading steps. Instead, CCU techniques were chosenthat could be implemented directly with the existing CO2 quality. Furthermore, it was concludedthat one reason why CCU technologies have not been widely implemented is internalbarriers between distributors and manufacturers (or users) of CCU technologies. Thus, theuse of carbon dioxide from biogas production and implementation of CCU technologies canbe promoted by eliminating barriers in companies, such as a lack of both knowledge andfinancial incentives.
Koldioxid från biogasproduktion betraktas i dagsläget som utan värde och släpps ut i atmosfärenvid uppgradering av biogas. Restgasen är en potentiell kolkälla och kan vara värdeskapandeför biogasprocessen. Genom att finna en lämplig värdeskapande process som utnyttjarkoldioxid går det att ge både ekonomiska och miljömässiga incitament till företag att utvecklasin verksamhet. I detta projekt undersöktes möjligheten att skapa värde av denna CO2.Genom en utvärdering av den tekniska mognadsgraden hos CCU-tekniker kunde en rekommendationges vid projektets slut. En analys av tekniska hinder, såsom föroreningar i gassammansättningen,såväl som hinder i form av kompetens och företagskultur undersöktes för attkunna ge en motiverad rekommendation. I projektet kartlades vilka värdeskapande systemsom skulle passa för biogasproducenter i en svensk kontext. Detta inkluderade etableradeuppgraderingstekniker för metan- och koldioxid som används i dagsläget. I projektet undersöktesäven lämpliga CCU-tekniker som kan samverka med de valda uppgraderingsprocessernaoch och agera värdeskapande. Utifrån denna kartläggning kunde det sedan anges vilkagemensamma, kritiska variabler som finns för dessa system. Därefter kunde en rekommendationav lämplig CCU-teknik ges beroende på den producerade CO2 sammansättningen. Enslutsats i projektet var att koldioxid från restgasen ofta var av hög koncentration (ca. 97-98 %)och ej innehöll några korrosiva eller toxiska komponenter, och att detta till stor del beror påhur rötkammaren är hanterad i produktionsprocessen. Således väcktes frågor kring vilka defaktiska begränsningarna för CCU är, då de inte torde vara tekniska. CCU-tekniker som visadesig vara av särskilt intresse var pH-reglering av avloppsverk, CO2 som näringssubstratför odling av mikroalger, samt tillverkning av kolsyreis för kyltransporter. Samtliga dessatekniker har tillräckligt hög teknisk mognadsgrad för att kunna installeras i dagsläget. AndraCCU-tekniker, såsom ”Power to gas”, kräver en hög CO2-koncentration och avfärdades dålitteraturstudien inte talade för den ekonomiska potentialen i dessa eftersom de kräver ytterligareuppgraderingssteg för CO2. Således valdes istället CCU-tekniker som skulle gå attimplementera direkt med den befintliga CO2 kvalitén. Vidare drogs slutsatsen att en anledningtill att CCU-tekniker inte har blivit vida implementerade till stor del är interna hindermellan distributörer och tillverkare (eller utnyttjare) av CCU-tekniker. Således kan användandetav koldioxid från biogasproduktion och implementering av CCU-tekniker främjasgenom att eliminera hinder hos företag. I projektet yttrade sig detta som bristande ekonomiskaincitament och okunskap. Ett ökat användande av CCU-tekniker kan också uppnås genomatt införa lagar och regler som begränsar användandet av föråldrade tekniker som drivs avfossila bränslen, och som kan ersättas av klimatvänliga CCU-tekniker.

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.