Дисертації з теми "Desulfurization reaction"
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1
Lindström, David. "A Study on Desulfurization of Hot Metal Using Different Agents." Doctoral thesis, KTH, Mikro-modellering, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-144025.
Повний текст джерелаАнотація:
This thesis deals with desulfurization of hot metal using different agents. The aim of this study was to improve the understanding of commonly used desulfurization agents such as fluidized CaO, CaC2, commercial-CaO, Mg, and mixtures of commercial-CaO-Mg. The possibility to use ZnO for desulfurization of hot metal was also investigated. The desulfurization mechanisms and kinetics of these agents were studied. A broad comparison of the desulfurization abilities of the agents was performed under the same experimental conditions. The experimental studies were carried out in a high temperature resistance furnace at 1773 K with good quenching ability and precise control of the oxygen partial pressure. The influence of ZnO in blast furnace slag on the sulfur removal potential was studied. It was found that ZnO does not stay in blast furnace slag under relevant oxygen potentials and consequently has no influence on its sulfur removal capacity. The reaction mechanism of Mg was studied by adding pure Mg into hot metal. It was found that most Mg (about 90 %) escaped as gas in less than two seconds, only providing a little desulfurization. MgS is not formed by homogenous nucleation, but on MgO particles originating from the surface of the added Mg metal. The growth of CaS around CaC2, fluidized CaO and commercial-CaO were measured and compared. The parabolic rate constants were evaluated to be 2.4∙10-7 [cm s-1] for CaC2, and 5∙10-7 [cm s-1] for fluidized CaO particles. The bigger parabolic rate constant of fluidized CaO explains why fluidized CaO achieved a much better desulfurization of hot metal than CaC2 under the same experimental conditions. Commercial-CaO performed less satisfactory in comparison to fluidized CaO powder. This was due to both its less reactive surface and agglomeration of the particles. Agglomerates and large CaO particles lead to 2CaO.SiO2 formation which hindered further utilization of CaO for desulfurization. The 2CaO.SiO2 formation was favored by a high oxygen potential. Since the desulfurization reaction of CaO not only produced CaS but also oxygen, the local oxygen concentration around big CaO particles was higher than around small particles. When small CaO particles were added together with Mg they quickly transformed to CaS. The Mg-gas helped to distribute the CaO particles in the hot metal and improved the kinetic conditions. The desulfurization abilities of some commonly used agents, namely fluidized CaO, CaC2, commercial-CaO, Mg, mixtures of commercial-CaO-Mg, and ZnO were studied and compared under the same experimental conditions. While fluidized CaO showed the best performance, commercial-CaO mixed with 20 mass % Mg achieved the second best desulfurization. Mg-granules performed slightly better than CaC2 and commercial-CaO, but somewhat less satisfactory compared to fluidized CaO and commercial-CaO-Mg mixtures. ZnO does not influence the sulfur concentration of hot metal.QC 20140404
2
Houda, Sara. "Oxidative desulfurization of marine fuels : optimization of reaction conditions and development of efficient catalysts." Thesis, Lille 1, 2019. http://www.theses.fr/2019LIL1R064.
Повний текст джерелаАнотація:
L'Organisation Maritime Internationale (OMI) a limité la teneur en soufre des combustibles marins dans les zones de contrôle des émissions de soufre (zones SECA) de 1 à 0,1 % en 2015 et la limitera, d’ici 2020, de 3,5 à 0,5 % dans toutes les zones maritimes. Les fiouls marins sont constitués des résidus lourds caractérisés par une teneur élevée en soufre, la majeure partie du soufre se trouvant dans des molécules dites réfractaires, très difficiles à éliminer par le procédé d'hydrodésulfuration existant, fonctionnant sous haute pression d’hydrogène. Cependant, ces molécules soufrées sont connues pour être plus réactives dans le procédé de désulfuration oxydante ou oxydésulfuration (ODS), réalisé dans des conditions douces sans consommation d'hydrogène. L'objectif de cette thèse est de proposer une désulfuration des fiouls marins par ODS. Toutefois, l’ODS sur les fiouls lourds est encore immature et les fiouls marins restent peu étudiés avec peu de publications reportées dans la littérature. Les travaux de cette thèse se sont donc tout d’abord portés sur le développement d'une méthodologie fiable pour l'analyse des composés soufrés dans les combustibles marins, avant une étude pour la détermination d’un catalyseur efficace et approprié, couplée à l'optimisation des conditions opératoires. Parmi une large variété de fiouls marins, trois fiouls ont été choisis, caractérisés par une viscosité élevée variant de 380 à 700 cSt. Les résultats d’analyse chimique ont révélé des teneurs élevées en soufre entre 0,6 et 3,2 % reflétant la variabilité de composition des combustibles marins. La réaction d'ODS a été effectuée par catalyse hétérogène à l'aide du système MoO3/Al2O3-H2O2 dans un réacteur batch. Les effets du temps de réaction, du rapport molaire oxydant/soufre (Ox/S) et du solvant d'extraction ont été étudiés. Le couplage des ultrasons avec l’ODS classique a permis d'obtenir de meilleurs taux de désulfuration grâce à l'effet de synergie amené par l’utilisation des ultrasons. Des études sur les effets de la teneur en molybdène, du dopage au phosphore et/ou au vanadium et du type de précurseur du molybdène ont été réalisées sur le catalyseur molybdène sur alumine. D'autres supports oxydes ont également été utilisés, améliorant considérablement les performances catalytiques. Dans des conditions de réaction optimales et avec les catalyseurs les plus efficaces, il a été possible d'oxyder toutes les charges sélectionnées et de les désulfurer pour les rendre compatibles avec les nouvelles normes 2020The International Maritime Organization (IMO) has limited marine fuel sulfur content in Sulfur Emission Control Areas (SECAs) from 1 to 0.1 wt.% in 2015 and will limit marine fuel sulfur content from 3.5 to 0.5 wt.% in all maritime areas by 2020. Marine fuels consist of heavy oils characterized by high sulfur content with refractory sulfur compounds difficult to remove using existing conventional high pressure hydrodesulfurization processes. However, these sulfides molecules appeared more reactive in oxidative desulfurization (ODS) process, carried out at mild conditions without hydrogen consumption. The objective of this thesis is to propose an oxidative desulfurization method of marine fuels. Nevertheless, ODS on heavy fuels is still immature and marine fuels are poorly studied with only few publications reported in literature. This work first focused on the development of a reliable methodology for the analysis of sulfur compounds in marine fuels before the study of an appropriate and efficient catalyst for marine fuel ODS reaction with optimized operating conditions. Among a large variety of marine fuels, three marine fuels were chosen with high viscosities that varied from 380 to 700 cSt. The results of chemical analysis revealed high sulfur content ranging from 0.6 to 3.2 wt.% reflecting the variability of the composition of marine fuels. ODS reaction was carried out by heterogeneous catalysis using MoO3/Al2O3-H2O2 system in batch reactor. The effects of reaction time, oxidant to sulfur molar ratio (Ox/S) and extracting solvent were investigated. Ultrasound assisted oxidative desulfurization coupled to normal mixing provided better desulfurization rates due to the synergetic effect provided by ultrasounds. Studies on the effects of molybdenum loading, phosphorus and/or vanadium doping and molybdenum precursor type were carried out on the alumina-supported molybdenum catalyst. Others oxide carriers were also employed, remarkably improving catalytic performances. Under the optimum conditions and with the most efficient catalysts, it was possible to oxidize and desulfurize all selected feeds making them compatible with the 2020 new regulations
3
Ben-Said, Lotfi. "Reaction kinetics and mechanisms of low temperature SO₂ removal by dry calcium-based sorbents." Ohio : Ohio University, 1993. http://www.ohiolink.edu/etd/view.cgi?ohiou1173758214.
Повний текст джерела
4
Carpenter, Russell Ellis Holly R. "Functional roles of conserved active site amino acids in the desulfonation reaction catalyzed by the alkanesulfonate monooxygenase from Escheria coli." Auburn, Ala, 2008. http://hdl.handle.net/10415/1426.
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5
Maldei, Michael. "Low-temperature dry scrubbing reaction kinetics and mechanisms limestone dissolution and solubility." Ohio : Ohio University, 1993. http://www.ohiolink.edu/etd/view.cgi?ohiou1175715332.
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6
Visneski, Michael J. "Modeling of the low temperature reaction of sulfur dioxide and limestone using a three resistance film theory instantaneous reaction model." Ohio : Ohio University, 1991. http://www.ohiolink.edu/etd/view.cgi?ohiou1173741863.
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7
Mills, Landon C. "IMPACT OF CONFORMATIONAL CHANGE, SOLVATION ENVIRONMENT, AND POST-TRANSLATIONAL MODIFICATION ON DESULFURIZATION ENZYME 2'-HYDROXYBIPHENYL-2-SULFINATE DESULFINASE (DSZB) STABILITY AND ACTIVITY." UKnowledge, 2019. https://uknowledge.uky.edu/cme_etds/105.
Повний текст джерелаАнотація:
Naturally occurring enzymatic pathways enable highly specific, rapid thiophenic sulfur cleavage occurring at ambient temperature and pressure, which may be harnessed for the desulfurization of petroleum-based fuel. One pathway found in bacteria is a four-step catabolic pathway (the 4S pathway) converting dibenzothiophene (DBT), a common crude oil contaminant, into 2-hydroxybiphenyl (HBP) without disrupting the carbon-carbon bonds. 2’-Hydroxybiphenyl-2-sulfinate desulfinase (DszB), the rate-limiting enzyme in the enzyme cascade, is capable of selectively cleaving carbon-sulfur bonds. Accordingly, understanding the molecular mechanisms of DszB activity may enable development of the cascade as industrial biotechnology. Based on crystallographic evidence, we hypothesized that DszB undergoes an active site conformational change associated with the catalytic mechanism. Moreover, we anticipated this conformational change is responsible, in part, for enhancing product inhibition. Rhodococcus erythropolis IGTS8 DszB was recombinantly produced in Escherichia coli BL21 and purified to test these hypotheses. Activity and the resulting conformational change of DszB in the presence of HBP were evaluated. The activity of recombinant DszB was comparable to the natively expressed enzyme and was competitively inhibited by the product, HBP. Using circular dichroism, global changes in DszB conformation were monitored in response to HBP concentration, which indicated that both product and substrate produced similar structural changes. Molecular dynamics (MD) simulations and free energy perturbation with Hamiltonian replica exchange molecular dynamics (FEP/λ-REMD) calculations were used to investigate the molecular-level phenomena underlying the connection between conformation change and kinetic inhibition. In addition to the HBP, MD simulations of DszB bound to common, yet structurally diverse, crude oil contaminates 2’2-biphenol (BIPH), 1,8-naphthosultam (NTAM), 2-biphenyl carboxylic acid (BCA), and 1,8-naphthosultone (NAPO) were performed. Analysis of the simulation trajectories, including root mean square fluctuation (RMSF), center of mass (COM) distances, and strength of nonbonded interactions, when compared with FEP/λ-REMD calculations of ligand binding free energy, showed excellent agreement with experimentally determined inhibition constants. Together, the results show that a combination of a molecule’s hydrophobicity and nonspecific interactions with nearby functional groups contribute to a competitively inhibitive mechanism that locks DszB in a closed conformation and precludes substrate access to the active site.
Limitations in DszB’s potential applications in industrial sulfur fixation are not limited to turnover rate. To better characterize DszB stability and to gain insight into ways by which to extend lifetime, as well as to pave the way for future studies in inhibition regulation, we evaluated the basic thermal and kinetic stability of DszB in a variety of solvation environments. Thermal stability of DszB was measured in a wide range of different commercially available buffer additives using differential scanning fluorimetry (DSF) to quickly identify favorable changes in protein melting point. Additionally, a fluorescent kinetic assay was employed to investigate DszB reaction rate over a 48 hr time period in a more focused group of buffer to link thermal stability to DszB life-time. Results indicate a concerningly poor short-term stability of DszB, with an extreme preference for select osmolyte buffer additives that only moderately curbed this effect. This necessitates a means of stability improvement beyond alteration of solvation environment. To this end, a more general investigation of glycosylation and its impact on protein stability was performed.
Post-translational modification of proteins occurs in organisms from all kingdoms life, with glycosylation being among the most prevalent of amendments. The types of glycans attached differ greatly by organism but can be generally described as protein-attached carbohydrate chains of variable lengths and degrees of branching. With great diversity in structure, glycosylation serves numerous biological functions, including signaling, recognition, folding, and stability. While it is understood that glycans fulfill a variety of important roles, structural and biochemical characterization of even common motifs and preferred rotamers is incomplete. To better understand glycan structure, particularly their relevance to protein stability, we modeled and computed the solvation free energy of 13 common N- and O-linked glycans in a variety of conformations using thermodynamic integration. N-linked glycans were modeled in the β-1,4-linked conformation, attached to an asparagine analog, while O-linked glycans were each modeled in both the α-1,4 and β-1,4-linked conformations attached to both serine and threonine analogs. Results indicate a strong preference for the β conformation and show a synergistic effect of branching on glycan solubility. Our results serve as a library of solvation free energies for fundamental glycan building blocks to enhance understanding of more complex protein-carbohydrate structures moving forward.
8
Besher, Elmarghani M. "Low temperature Claus reactor studies." Thesis, University of British Columbia, 1990. http://hdl.handle.net/2429/30563.
Повний текст джерелаАнотація:
A small-scale fluidized bed reactor (0.1m ID, 0.86m high) was used to carry out the Claus reaction
2H₂S + SO₂ ⇌3/X Sx + 2H₂O
at low temperatures (100 to 150°C) where elemental sulphur condensed on the catalyst particles (Kaiser alumina S-501, 195µm mean particle size). The experimental apparatus was similar to that described by Bonsu and Meisen (1985). The feed gas consisted of pure nitrogen mixed with H₂S and SO₂ in the ratio of 2 to 1. The H₂S concentration was varied from 200 to 1300 ppm. The feed gas flow rate ranged from approximately 1.4 to 5.6 m³/h. The corresponding U/Umf ranges were approximately 2.2 to 8.8. The bed heights varied from 0.12 to 0.38m.
It was found that the experimental conversion efficiencies ranged from 60 to 96% and that they were less than those predicted thermodynamically. The conversion efficiency was found to increase with H₂S concentration and catalyst bed height; it decreased with gas flow rate. Contrary to thermodynamic predictions, the conversion efficiency increased with temperature. These results suggest that thermodynamic equilibrium was not achieved in the reactor. The decline in conversion due to catalyst fouling was measured
as a function of catalyst sulphur content.
The experimental results could be interpreted by means of a bubbling bed model. New analytical expressions for predicting the overall conversion and the concentration profiles were developed for reactions of order n. For the Claus reaction, where n=1.5, good agreement was found between the model predictions and experimental values. The model
properly discribed the observed behavior resulting from changes in feed concentration, bed temperature, U/Umf and static bed height.
The bubbling bed model was used to predict the effect of particle size on conversion for various operating gas velocities and bed dimensions. The model predictions showed that the canversion improved with decreasing particle size and that the improvement depended on U/Umf.
The bubbling bed model was modified for conditions where condensed sulphur fouled the catalyst. A catalyst deactivation function, derived from first principles and based on catalyst sulphur content, was incorporated into the rate expression. The modified model predicted the the experimental measurements well and conclusions are drawn regarding the continuous operation of fluidized bed Claus reactor operating under sulphur condensing conditions.
A general procedure is presented to demonstrate the applicability of the bubbling bed model in the design of large scale reactors; examples for specific conditions are given.
Attrition tests were performed on the catalyst at U/Umf=5.1 and room temperatures. It was found that most of the attrition occurred in the first few hours when the catalyst particles were rough. The overall test results indicated that attrition of the catalyst was negligibly small thereby suggesting the suitability of the Kaiser S-501 catalyst for long term use in fluidized bed Claus reactors.Applied Science, Faculty of
Chemical and Biological Engineering, Department of
Graduate
9
Adikesavalu, Ravichandran. "Preliminary modeling of in-duct desulfurization using condensation aerosols." Ohio : Ohio University, 1997. http://www.ohiolink.edu/etd/view.cgi?ohiou1177616476.
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10
Berry, David A. "Investigation of hot gas desulfurization utilizing a transport reactor." Morgantown, W. Va. : [West Virginia University Libraries], 1999. http://etd.wvu.edu/templates/showETD.cfm?recnum=500.
Повний текст джерелаАнотація:
Thesis (M.S.)--West Virginia University, 1999.Title from document title page. Document formatted into pages; contains vi, 101 p. : ill. (some col.) Includes abstract. Includes bibliographical references (p. 82-85).
11
Pekay, Lars Arthur. "Investigations in coal chemistry : advancements of analytical techniques and reactive oxidative desulfurization /." The Ohio State University, 1992. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487760357819292.
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12
Duespohl, Dale W. "Modeling and optimization of a cross-flow, moving-bed, flue gas desulfurization reactor." Ohio : Ohio University, 1995. http://www.ohiolink.edu/etd/view.cgi?ohiou1179511746.
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13
Duggirala, Ravi Kumar Roy Christopher J. "Computational fluid dynamics simulation of chemically reacting gas flows through microfibrous materials." Auburn, Ala, 2008. http://repo.lib.auburn.edu/EtdRoot/2008/SPRING/Aerospace_Engineering/Dissertation/Duggirala_Ravi_35.pdf.
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14
Fox, Brandy R. 1981. "Investigations into the Oxidative Desulfurization Activity in a Film-Shear Reactor, the Source of Enhanced Reactivity, and Other Potential Applications." Thesis, University of Oregon, 2011. http://hdl.handle.net/1794/11529.
Повний текст джерелаАнотація:
xviii, 242 p. : ill. (some col.)Fuel purification is an extremely active area of research in today's green world. Specifically, desulfurization of fuels is an important area of research for two reasons. First, any sulfur present in fuels generates SOx pollutants that are hazardous to human health and also contribute to acid rain. Secondly, even trace sulfur contaminants prohibit the use of fuel streams in fuel cells. However, achieving near-zero sulfur levels with existing technology is impractical. The work in this thesis investigates a new process for the removal of sulfur from fuel streams using a film-shear reactor (based on a process known as oxidative desulfurization), and goes on to investigate the mode of activation for the process within the reactor through a study of the reactor conditions. Additionally, other applications of the film-shear reactor, including mechanical activation of molecules and controlled nanoparticle synthesis are explored. Chapter I outlines the current status of oxidative desulfurization research, highlighting the strengths of the method, innovative approaches and drawbacks to the various approaches. Chapters II and III go on to discuss the enhancement of the process in the film-shear reactor using model fuels and a variety of substrates. This method was found to significantly enhance the oxidative desulfurization process, reducing both the time and temperature required to achieve considerable sulfur removal. Levels of desulfurization that require hours at elevated temperatures by conventional stirring methods were obtainable on the scale of seconds at or below room temperature. Chapter IV offers investigations into the conditions within the film-shear reactor, and also presents studies of the ability of the high shear rates obtained in the reactor to mechanically activate molecules. Chapter V extends the applicability of the film-shear reactor to nanoparticle synthesis through investigation of two titania synthesis methods utilizing the film-shear reactor. Appendices A and B offer supplementary information to enhance the studies presented in Chapters II and III, while Appendices C, D, and E highlight work done investigating the ability of platinum complexes to hydrate nitriles and cyanohydrins. This dissertation includes previously published and unpublished co-authored material.
Committee in charge: Victoria J. DeRose, Chairperson; David R. Tyler, Advisor; Kenneth M. Doxsee, Member; Catherine J. Page, Member; Mark H. Reed, Outside Member
15
Loibl, Simon. "Auxiliar-vermittelte Peptidfragmentverknüpfung: Synthese und Anwendung leistungsfähiger Nα-Auxiliare für die erweiterte native chemische Peptidligation". Doctoral thesis, Humboldt-Universität zu Berlin, 2018. http://dx.doi.org/10.18452/18731.
Повний текст джерелаАнотація:
Chemoselektive Peptidfragmentverknüpfungsmethoden sind ein zentrales Element der chemischen Peptid- und Proteinsynthese. Auf der Suche nach einem „universellen Werkzeug für die Peptidligation“ wurde in den vergangenen zwei Jahrzenten eine Vielzahl unterschiedlicher Hilfsmolekülen (Auxiliare) entwickelt. Trotz des enormen Forschungaufwandes blieben bisher verfügbare Nα-Auxiliare jedoch in ihrer Anwendung auf glycinhaltige Ligationsstellen beschränkt. Im Fall der häufig verwendeten säurelabilen Nα-Auxiliare müssen zudem starke Säuren oder Supersäuren eingesetzt werden, um das Hilfsmolekül nach der Peptidligation zu entfernen. Dabei wurde häufig die Spaltung der zuvor aufgebauten Amidbindung als unerwünschte Nebenreaktion beobachtet.
In der vorliegenden Arbeit wurde die Synthese von acht Nα-Auxiliaren erarbeitet und deren Anwendung in der erweiterten nativen chemischen Ligation untersucht. Dabei konnten sechs Hilfsmoleküle identifiziert werden, welche die Auxiliar-Abspaltung unter mild-basischen Bedingungen ermöglichten. Von besonderer Bedeutung war das 2-Mercapto-2-phenethyl-Grundgerüst, welches im Gegensatz zu bisher beschriebenen Nα-Auxiliaren erstmals den Zugang zu sterisch anspruchsvollen Verknüpfungstellen, jenseits von Glycin, gestattete. Der Nutzen des Auxiliars wurde in die chemische Totalsynthese zweier antimikrobieller Peptide demonstriert. Durch die Verwendung eines 13C-markierten Hilfsmoleküls konnte der Mechanismus der radikalischen Auxiliar-Abspaltungsreaktion in NMR-Experimenten detailliert untersucht werden. Zusätzlich wurde das 2-Mercapto-2-phenethyl-Auxiliar in einer neuen Methode der chemischen Proteinsynthese eingesetzt, welche die gewünschten Proteine ohne eine einzige HPLC-Reinigung in reiner Form lieferte. Im letzen Teil der Arbeit wurde mit dem 2-Selenol-2-phenethyl-Grundgerüst erstmals die Anwendung eines Selenol-funktionalisierten Nα-Auxiliars beschrieben. Das Hilfsmolekül ermöglichte besonders schnelle Verknüpfungsreaktionen und konnte zudem rasch mit hoher Selektivität entfernt werden.Chemoselective ligation methods are an essential element of chemical peptide and protein synthesis. The search of a „universal tool for peptide ligation“ led to a range of different ligation auxiliaries over the last two decades. Despite the intense research in this field established Nα-auxiliaries remained limited to glycine-containing ligation sites. Furthermore, the application of frequently used acid-labile Nα-auxiliaries requires strong acids or superacids to remove the auxiliary after the ligation reaction. Under these harsh acidic conditions the cleavage of the established amide bond has been observed as an undesired side-reaction. This work describes the synthesis of eight Nα-auxiliaries and their application in extended native chemical ligation. Six helping molecules were identified enabling auxiliary cleavage under mild-basic conditions. Perhaps most important and in contrast to previously reported Nα-auxiliaries, the 2-mercapto-2-phenethyl group facilitated access to sterically demanding ligation sites, beyond glycine. The synthetic utility of the auxiliary was demonstrated by the chemical total synthesis of two antimicrobial peptides. The application of a 13C-labelled scaffold allowed a detailled study oft the radical auxiliary cleavage reaction by NMR-spectroscopy. Additionally, the 2-mercapto-2-phenethyl auxiliary was utilised for a novel method of chemical protein synthesis, which delivered the desired proteins without a single HPLC-purification in high purity. Finally, a selenol-functionalized Nα-auxiliary is described for the first time by introducing the 2-selenol-2-phenethyl mojety. This scaffold enabled execptionally rapid peptide ligations and is readily removed with high selectivity.
16
Karmal, Said. "Caractérisation des catalyseurs CoMo/Al(2)O(3) sulfurés à l'aide de réactions modèles." Poitiers, 1988. http://www.theses.fr/1988POIT2313.
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TAVARES, DENISE T. "Análise quantitativa de alcanolaminas e CO2 no processo de absorção química via espectroscopia no infravermelho." reponame:Repositório Institucional do IPEN, 2015. http://repositorio.ipen.br:8080/xmlui/handle/123456789/26367.
Повний текст джерелаАнотація:
Submitted by Claudinei Pracidelli (cpracide@ipen.br) on 2016-06-22T10:57:18Z
No. of bitstreams: 0Made available in DSpace on 2016-06-22T10:57:18Z (GMT). No. of bitstreams: 0
Dissertação (Mestrado em Tecnologia Nuclear)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
18
Gupta, Puneet. "Regenerable metal oxide Composite particles and their use in novel chemical processes." The Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=osu1143225336.
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"Tungsten hexacarbonyl mediated C-S bond cleavage reactions." Chinese University of Hong Kong, 1988. http://library.cuhk.edu.hk/record=b5885974.
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20
Chu, Chen-Yeon, and 朱正永. "Desulfurization in an Internally Circulating Fluidized Bed Reactor." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/85655093714989056979.
Повний текст джерелаАнотація:
博士國立清華大學
化學工程學系
93
In this study an attempt was made to use internally circulating fluidized bed reactor (ICFBR) as a flue gas desulfurization reactor. The height of the bed was 2.5 m, and the inner diameter was 9 cm. The bed materials were calcium sorbent and silica sand. One of the special features of the ICFBR is high attrition of the particles in the bed, which would remove the product layer of sulfation and increase the utilization of the calcium sorbent. The other features are easy control of the solids circulation rate and gas residence time in the bed by individually adjusting the gas velocity in the annulus and the draft tube, which would increase the efficiency of the desulfurization process. The effects of the operating parameters including relative humidity, particle size of the calcium sorbent, inlet concentration of SO2, difference superficial gas velocity in the draft tube and the annulus and superficial gas velocity in the draft tube on attrition rate, calcium sorbent conversion, solids circulation rate and SO2 removal efficiency in the ICFBR were investigated. It was found that a higher relative humidity had a higher calcium sorbent conversion, but had a lower attrition rate and solids circulation rate. The removal efficiency of SO2 had a maximum value at steady state when the relative humidity was from 40 to 80%. When RH = 50、60 and 70% RE decreased initially and then increased. After that RE decreased again until a steady state was reached. A smaller particle size of calcium sorbent had a higher attrition rate, a higher solids circulation rate and a higher removal efficiency of SO2. In addition, the effect of the inlet concentration of SO2 on calcium sorbent conversion, attrition rate and solids circulation rate was negligible from 200 ppm to 500 ppm, but the removal efficiency of SO2 was decreased with increasing the inlet SO2 concentrations. Moreover, a higher total superficial gas velocity and a higher difference superficial gas velocity in the draft tube and the annulus had a higher attrition rate, but had a lower calcium sorbent conversion. However, the solids circulation rate might have a maximum value with respect to the difference superficial gas velocity in the draft tube and the annulus at the same total superficial gas velocity in the bed. A higher difference superficial gas velocity in the draft tube and the annulus had a higher removal efficiency of SO2 that was resulted by a higher reactivity of calcium sorbent due to a higher attrition rate. Futhermore, a higher attrition rate had a higher total volume of the flue gas treated. Finally, an attrition rate model proposed in this study could predict the attrition rate satisfactorily. A model to predict the removal efficiency of SO2 at steady state in ICFBR was also proposed. It assumed that the draft tube section was a bubbling fluidized bed while the annulus section was a moving bed. In addition, the effects of the calcium sorbent conversion, attrition rate and gas-bypassing fractions on the removal efficiency of SO2 at steady state were also taken into account in this model. It was found that the values of the removal efficiency of SO2 at steady state predicted by this model agreed with the experimental results.
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Hsueh, Kuang-Wei, and 薛光偉. "Flue Gas Desulfurization in a Fluidized Bed Reactor." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/44314234459282095779.
Повний текст джерелаАнотація:
碩士國立清華大學
化學工程學系
87
Abstract There are three types of commercial SO2 removal system: (1) Dry process, (2) Semi-dry process, and (3) Wet scrubbing process. The calcium utilization and SO2 removal efficiency are low for the dry process. For the semi-dry process, the calcium utilization is higher, but fouling and corrosion of the nozzles and the reactor could be severe. For the wet scrubbing system, a wastewater treatment system is required.The problems mentioned above can be eliminated if gas-solid fluidized bed reactor is used as the desulfurization apparatus. The advantages of the gas-solid fluidized bed reactor are: (1) The desulfurization products are dry so that we do not need a wastewater treatment unit. (2) The bed structure is simple, the equipment cost is low and easy to operate and maintain. (3) The calcium utilization is increased by the special attrition and elutriation mechanism of the fluidized bed, thus the cost of operation is decreased. Therefore, fluidized bed desulfurization technology is worthy of study and development.A bubbling fluidized bed reactor is used as the desulfurization apparatus in this study. The height of the bed is 2.5m, and the diameter is 9cm. The bed material is hydrated lime and silica sand. The effects of the operating parameters of flue gas desulfurization including relative humidity, temperature, superficial gas velocity, the weight ratio of hydrated lime and silica sand, and particle size on SO2 removal efficiency and calcium utilization in the fluidized bed will be investigated.We find temperature effect in our system is negligible from 40 to 65oC. Higher relative humidity has higher calcium utilization (R.H.=20%-80%) and higher sulfur dioxide removal efficiency. Smaller diameter of calcium hydroxide has higher calcium utilization and higher sulfur dioxide removal efficiency. The optimum weight ratio of silica sand and calcium hydroxide is 3. Although the lower superficial gas velocity causes the higher sulfur dioxide removal efficiency and higher calcium utilization, but the SO2 treated volume is maximum when the superficial gas velocity is minimum fluidization velocity. Finally, the attrition rate model by Lee et al. (1993) can predict our bed weight precisely and the value of ko is 9.48×10-6 (s-1) and Ea = 4.69×10-4 (kJ/kg).
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Chen, Cheng-Chun, and 陳政群. "A Study of Flue Gas Desulfurization in a Fluidized Bed Reactor." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/16468428014807995723.
Повний текст джерелаАнотація:
碩士逢甲大學
化學工程研究所
85
Several technologies have been used to abatement of SOx emission in flue gas spray-dryer scrubbers, wet scrubbing, etc. This paper will concern with controlling SO2 emission of flue gas with three absorbents such as lime, limestone, and dolomite in a fluidized bed. Experimental work was carried out in a batch fluidized bed with 6.62cm inner diameter and 2.5m height and perforated distributor. In-situ combustion analyzer is used to record SO2 concentration during the operating. The running temperature is controlled at ambient situation. The SO2 concentration is handled between 400ppm and 1100 ppm. The particle size of lime (CaO) is varied from 88um to 1000um. The experimental results show that:(1)at ambient temperature limestone and dolomite are inactive for SO2 controlled. (2)at ambient temperature, 500ppm SO2, 800grams of CaO with mean size from 103um to 295um, flue gas flow rate of 36.13 l/min, SO2 Removal Efficiency can reach 95% for more than 10 minutes .(3)SO2 Removal Efficiency is increase with weight of lime used. (4)dry fluidized bed scrubber has not good performance of high SO2 concentration ( >1000ppm ) at ambient temperature. (5)at higher operating velocities, the performance is poor caused by shorter residence time. The optimum operation velocity is around minimum fluidizedation velocity of absorbent. (6)for larger particle size, say larger than 500um, there ismore energy consumed and lower surface area per unit react volume, but too smaller particle size will cause elutriation. The optimum particle size is from 88um to 351 um in this study.
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Koech, Lawrence. "The dissolution of limestone, coal fly ash and bottom ash in wet flue gas desulphurization." Thesis, 2015. http://hdl.handle.net/10352/356.
Повний текст джерелаАнотація:
M. Tech. (Department of Chemical Engineering, Faculty of Engineering and Technology): Vaal University of TechnologyStrict environmental regulation on flue gas emission has led to the implementation of FGD technologies in power stations. Wet FGD technology is commonly used because it has high SO2 removal efficiency, high sorbent utilization and due to availability of the sorbent (limestone) used. SO2 is removed by passing flue gas through the absorber where it reacts with the slurry containing calcium ions which is obtained by dissolution. This study presents the findings of the dissolution of a calcium-based material (limestone) for wet FGD process. This was done using a pH stat apparatus and adipic acid as acid titrant. Adipic acid was used because of its buffering effect in wet FGD process. The conditions used for this study are similar to what is encountered in a wet FGD process. The extent of dissolution was determined by analyzing the amount of calcium ions in solution at different dissolution periods. The dissolution kinetics were correlated to the shrinking core model and it was found out that chemical reaction at the surface of the particle is the rate controlling step. This study also investigated the dissolution of coal fly ash and bottom ash. Their dissolution kinetics showed that the diffusion through the product layer was the rate controlling step due to an ash layer formed around the particle. The formation of ash layer was attributed to pozzolanic reaction products which is calcium-alumino-silicate (anorthite) compounds were formed after dissolution. The effect of fly ash on the dissolution of rate of limestone was also studied using response surface methodology. Limestone reactivity was found to increase with increase in the amount of fly ash added and the pH was found to be strong function of the rate constant compared to other dissolution variables. The presence of silica and alumina in fly ash led to a significant increase in the specific surface area due to hydration products formed after dissolution.
Eskom
24
Mei-LinChen and 陳美伶. "Treatment of Reactive Black 5 by nickel ferrite and desulfurization slag induced H2O2 process." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/21249143353854138344.
Повний текст джерела
25
Nawaf, A. T., S. A. Gheni, Aysar Talib Jarullah, and Iqbal M. Mujtaba. "Improvement of fuel quality by oxidative desulfurization: Design of synthetic catalyst for the process." 2015. http://hdl.handle.net/10454/7926.
Повний текст джерелаАнотація:
YesThe present study explored a novel oxidative desulfurization (ODS) method of light gas oil fuel, which combines a catalytic oxidation step of the dibenzothiophene compound directly in the presence of molecular air as oxidant to obtain high quality fuel for light gas oil. In chemical industries and industrial research, catalysis play a significant role. Heightened concerns for cleaner air together with stricter environmental legislations on sulphur content in addition to fulfill economic have created a driving force for the improvement of more efficient technologies and motivating an intensive research on new oxidative catalysts. As the lower quality fuel becomes more abundant, additional challenges arise such as more severe operation conditions leading to higher corrosion of the refinery installations, catalyst deactivation and poisoning. Therefore, among the technologies to face these challenges is to develop catalysts that can be applied economically under moderate conditions. The objective of this work is to design a suitable synthetic catalyst for oxidative desulfurization (ODS) of light gas oil (LGO) containing model sulphur compound (dibenzothiophene (DBT)) using air as oxidant and operating under different but moderate operating conditions. The impregnation method is used to characterize two homemade catalysts, cobalt oxide (Co3O4/γ-Al2O3) and manganese oxide (MnO2/γ-Al2O3). The prepared catalysts showed that the manganese oxide has a good impregnation (MnO2=13%), good pore size distribution and larger surface area. A set of experiments related to ODS of dibenzothiophene has been carried out in a continuous flow isothermal trickle bed reactor using light gas oil as a feedstock utilizing both catalysts prepared in-house. At constant pressure of 2 bar and with different initial concentration of sulphur within dibenzothiophene, the temperature of the process was varied from 403K to 473K and the liquid hourly space velocity from(LHSV) was varied from 1 to 3 hr-1. The results showed that an increase in reaction temperature and decreasing in LHSV, higher conversion was obtained. Although both catalysts showed excellent catalytic performance on the removal of molecule sulphur compound from light gas oil, the catalyst MnO2 catalyst exhibited higher conversion than Co3O4 catalyst at the same process operating conditions.
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Tsai-ChiLian and 連彩綺. "Sorption of Carbon Dioxide from Oxy-fuel Combustion by Desulfurization Slag in a Fluidized Bed Reactor." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/88837432915367567858.
Повний текст джерелаАнотація:
碩士國立成功大學
環境工程學系
103
In recent years, human being rely on the fossil fuel due to the booming economy. A great amount of carbon dioxide releasing from fossil fuel combustion cause the global warming. As a result, it is a serious issue to capture carbon dioxide for global citizens today. Oxy-fuel combustion system is a carbon dioxide capture technology, contributing to higher capture efficiency due to concentrated CO2, decreasing processing cost, and constructing easily. Recently, it is considered as a new option for power generation. In fluidized bed system, it has high heat transfer and mass transfer coefficient and it is easy to reach isothermal condition which fits the high temperature carbonation by dry techniques. Utilizing desulfurization slag as sorbent not only reuses the waste but also reduces cost. In this study, desulfurization slag was used to absorb carbon dioxide from oxy-fuel combustion in a fluidized bed reactor. Results of this study are described as follows： 1. The minimum fluidized velocity decreases along with the increasing temperature both for empirical model prediction and experimental results. However, the minimum fluidized velocity at 700oC is slight higher than at 600 oC due to slag sintering. Besides, the assumption of Ergun equation neglects the interparticle force causing that the experimental results are higher than empirical results. 2. According to the results of ICP and XRD analysis, the contents of calcium hydroxide in desulfurization slag of 150-300 μm and 75-106 μm are 15.76% and 18.86%, respectively. From TGA analysis, the desulfurization slags of both 150-300 μm and 75-106 μm have a considerable slag utilization (24.5-34.09%) from 450oC to 580oC. 3. When the gas velocity reaches minimum fluidized velocity, the utilization of the slag with size 150-300 μm will increase from 28.7% of a fixed bed mode to 41.2%. Fluidized bed reactor is better than a fixed bed reactor due to the high heat transfer and mass transfer rate. In a fluidized bed reactor, as the weight hourly space velocity becomes higher, the slag utilization decreases as a result of the short residence time. Besides, the smaller size of the desulfurization slag, the higher of the utilization. 4. The optimal operating temperature is about 600oC for the CO2 removal with desulfurization slag of 150-300 μm. Furthermore, the effects of adding water vapor on the carbonation of desulfurization slag were conducted. The results illustrate that the water vapor content can enhance the carbonation reaction and its optimal content is 5% which the slag utilization is 42.2% with 1.5 Umf. However, the slag utilization decreases as the water vapor content is greater than 5%, resulting from competitive sorption and sintering. 5. The results of XRD, SEM, EDS, Mapping and FTIR analyses indicate the structure and bonding for desulfurization slags before and after carbonation. It confirms the appearance of CaCO3 after carbonation reaction. 6. The deactivation model regressions of the experimental breakthrough curves have been conducted and the results show that the model is in good agreement with the experimental data. The activation energies for the reaction and deactivation are 58.9 and 8.7 kJ mol−1, respectively.
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LIU, DIAN-MO, and 劉典謨. "Study on the characteristics of ebullatedbed reactor and its application to the desulfurization, demetallation of residual oil." Thesis, 1986. http://ndltd.ncl.edu.tw/handle/74235627303810178564.
Повний текст джерела
28
Nawaf, A. T., S. A. Gheni, Aysar Talib Jarullah, and Iqbal M. Mujtaba. "Optimal Design of a Trickle Bed Reactor for Light Fuel Oxidative Desulfurization based on Experiments and Modelling." 2015. http://hdl.handle.net/10454/7928.
Повний текст джерелаАнотація:
YesIn this work, the performance of oxidative desulfurization (ODS) of dibenzothiophene (DBT) in light gas oil (LGO) is evaluated with a homemade manganese oxide (MnO2/γ-Al2O3) catalyst. The catalyst is prepared by Incipient Wetness Impregnation (IWI) method with air under moderate operating conditions. The effect of different reaction parameters such as reaction temperature, liquid hour space velocity and initial concentration of DBT are also investigated experimentally. Developing a detailed and a validated trickle bed reactor (TBR) process model that can be employed for design and optimization of the ODS process, it is important to develop kinetic models for the relevant reactions with high accuracy. Best kinetic model for the ODS process taking into account hydrodynamic factors (mainly, catalyst effectiveness factor, catalyst wetting efficiency and internal diffusion) and the physical properties affecting the oxidation process is developed utilizing data from pilot plant experiments. An optimization technique based upon the minimization of the sum of the squared error between the experimental and predicted composition of oxidation process is used to determine the best parameters of the kinetic models. The predicted product conversion showed very good agreement with the experimental data for a wide range of the operating condition with absolute average errors less than 5%.
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Nawaf, A. T., Aysar Talib Jarullah, S. A. Gheni, and Iqbal M. Mujtaba. "Development of Kinetic and Process Models for the Oxidative Desulfurization of Light Fuel, Using Experiments and the Parameter Estimation Technique." 2015. http://hdl.handle.net/10454/7927.
Повний текст джерелаАнотація:
YesThe oxidative desulphurization (ODS) of light gas oil (LGO) is investigated with an in-house designed cobalt 11 oxide loaded on alumina (γ-Al2O3) catalyst in the presence of air as oxidizing agent under moderate operating 12 conditions (temperature from 403 to 473 K, LHSV from 1 to 3 hr-1, initial concentration from 500 to 1000 13 ppm). Incipient Wetness Impregnation method (IWI) of cobalt oxide over gamma alumina (2% Co3O4/γ-14 Al2O3) is used for the preparation of the catalyst. The optimal design of experiments is studied to evaluate the 15 effects of a number of process variables namely temperature, liquid hourly space velocity (LHSV) and 16 concentration of dibenzothiophene and their optimal values were found to be 473 K, 1hr-1 and 1000 ppm 17 respectively. For conversion dibenzothiophene to sulphone and sulphoxide, the results indicates that the 18 Incipient Wetness Impregnation (IWI) is suitable to prepare this type of the catalyst. Based on the 19 experiments, mathematical models that represent a three phase reactor for describing the behavior of the ODS 20 process are developed. 21 In order to develop a useful model for simulation, control, design and scale-up of the oxidation process, 22 accurate evaluation of important process parameters such as reaction rate parameters is absolutely essential. 23 For this purpose, the parameter estimation technique available in gPROMS (general Process Modelling 24 System) software is employed in this work. With the estimated process parameters further simulations of the 25 process is carried out and the concentration profiles of dibenzothiophene within the reactor are generated.
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kai-junLiang and 梁凱鈞. "Sorption of Carbon Dioxide from Oxy-fuel Combustion by Desulfurization and Water-quenched slags in a Fluidized Bed Reactor." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/y3m85v.
Повний текст джерелаАнотація:
碩士國立成功大學
環境工程學系
105
In recent years, fossil fuel has been widely used by human thus booming the economy. A great amount of carbon dioxide releasing from fossil fuel combustion causes the global warming. As a result, carbon dioxide capture and storage techniques are needed to solve this issue. Oxy-fuel combustion system is a carbon dioxide capture technology, contributing to higher capture efficiency due to concentrated CO2, decreasing processing cost, and easy alterations. This study used the water-quenched slag and the desulfurization slag as the sorbents. It not only reduces the cost of sorbent but also has a high calcium content that can highly absorb CO2 of the flue gas in a fluidized bed reactor system and increases the reutilization of the waste. Therefore, this study simulated oxy-fuel combustion condition to capture carbon dioxide with De-S and GGBS slags in a fluidized bed reactor system at high temperature. Results of this study are summarized as follows： 1.With the increasing temperature both for empirical model prediction and experimental results, the minimum fluidized velocity of De-S and GGBS slags at various particle sizes have a decrease trend. However, the particle size and particle density of slags can influence the values of the minimum fluidized velocity at various temperatures. 2.According to the results of TGA analysis, De-S and GGBS slags react with carbon dioxide at various temperatures, weight change of the De-S slag is much higher than the GGBS slag. 3.Regarding to the various operating parameters such as temperature, water vapor, flow velocity and CO2 concentration, it can be found that an increase of the carbon dioxide concentration can significant impact the slags sorption utilization. When the gas velocity reaches minimum fluidized velocity, the sorption utilization sorption of the slags at various particle sizes will be the best. As the velocity becomes higher than minimum fluidized velocity, the slag sorption utilization decreases. The little water vapor for 5% can promote CO2 capture of slag at various particle sizes and excessive water vapor for 10% at various particle sizes affect pore structure. 4.The best operating temperature is about 600oC for the CO2 capture with De-S slag at various particle sizes; the best operating temperature is about 500oC for the CO2 capture with GGBS slag at various particle sizes. It can be found that De-S slags at various particle sizes for the CO2 capture are superior to the GGBS slags . 5.The pilot plant is 10 times the size of the laboratory set, conducting the capture of carbon dioxide from air and oxy-fuel combustion conditions. It can be found that the utilization of 150-300μm De-S slag at 600 oC is better than other temperature. The utilization of 150-300μm De-S slags for the capture of carbon dioxide from oxy-fuel combustion is higher than air combustion due to the increase in carbon dioxide partial pressure of the flue gas from oxy-fuel combustion.
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Gomes, Neide Marisa Costa. "Advanced Supported and Non Supported Polyoxometalate Materials for Oxidative Catalytic Reactions." Master's thesis, 2017. http://hdl.handle.net/10362/29114.
Повний текст джерелаАнотація:
In this work, new heterogeneous catalysts based on mesoporous silica nanoparticles (MSNPs) with different cations of ionic liquids (ILs) covalently bonded to their surface, 1-butyl-3-methylimidazolium ([C4MIM]+), 1-butylpyridinium ([C4Py]+) and tetrabutylammonium ([N4,4,4,4]+), and with the polyoxometalate (POM) derived from phosphomolybdic acid ([H(3-x)PMo12O40]x-) as anions were prepared. Their analogous homogeneous compounds were also prepared for comparison (POM-ILs), [N4,4,4,4]3[PMo12O40], [C4MIM]3[PMo12O40] and [C4Py]3[PMo12O40].
The catalysts were characterized by elemental analysis, in solution (1H and 31P) and solid-state (13C and 31P) NMR spectroscopy, DLS (for the silica nanoparticles), SEM, TEM, EDS, X-ray fluorescence spectroscopy, FTIR spectroscopy and ICP-MS.
The homogeneous catalysts were applied in the preliminary oxidation reactions of two lignin model compounds, cinnamyl alcohol and guaiacol, varying the reaction conditions (time, presence of hydrogen peroxide and use of conventional heating or microwave heating). The results obtained were characterized by solution 1H NMR spectroscopy. The oxidation of cinnamyl alcohol seems to be promissory using microwave heating process in comparison to conventional process.
All catalysts prepared were also applied in the oxidative desulfurization reactions of a multicomponent model diesel, composed by 1-benzothiophene, dibenzothiophene, 4-methyldibenzothiophene and 4,6-dimethyldibenzothiophene in order to study the performance of each catalyst in the removal of sulfur compounds present in fuels. This part of the study was performed in Faculdade de Ciências from Universidade do Porto, and the catalytic performance was evaluated by gas chromatography.
The heterogeneous catalysts had the most promising results, in particular MSNPs-[N4,4,4,4]POM achieving 100% of total desulfurization after only 2 hours. Its recycling ability was evaluated for three consecutive cycles and it was observed an increase of the catalytic efficiency for the second and third cycles reaching the complete desulfurization of the model diesel after just 1h instead of the 2h. The catalysts with cation tetrabutylammonium had the best results in both heterogeneous and homogeneous catalysis in comparison to the other two catalysts. In general, all catalysts tested had interesting results.