CO2 Conversion Via Reverse Water-gas Shift Using Multicomponent Catalysts PDF Download

Author: Liuqingqing Yang
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Author: Xianyun Liu
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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Nowadays, serious concern exists about atmospheric CO2 increase related with environmental impact and climate change. The reuse of CO2 through its chemical recycling is a promising route, which could contribute to the decrease of globally emitted CO2. Today CO2 is not only considered a waste, CO2 can be also conveniently used as raw material for industrial applications, and the development of new or improved processes for its use can contribute for a sustainable development. CO2 is a molecule which is thermodynamically stable, and its activation requires high energy input to overcome the energy barrier for the dissociation of C=O bond. However, CO2 can be selectively activated in the presence of H2 through catalytic processes, under appropriate conditions of pressure and temperature. In this doctoral research project, the main objective is related with the development of new catalysts for efficient CO2 conversion to CO via the reverse water gas shift reaction (RWGS) under mild conditions. For such purposes, new multicomponent CuZnOGa2O3MxOy (M=Al, Zr) and MoxC-based catalysts were prepared, deeply characterized and studied under different experimental conditions in the RWGS reaction. CuZnxGaM (M=Al, Zr) catalysts were prepared using a surfactant-free sol-gel method. CuZnxGaZr showed higher surface area, easier reducibility of CuO and a higher amount of surface Cu, Zn and Ga species than CuZn and CuZnxGaAl. Reduced catalysts were highly performant in the RWGS reaction at 250-270 °C, 3 MPa using a CO2/H2/N2=1/3/1 reactant mixture. CuZnxGaZr were more active than CuZn and CuZnxGaAl catalysts. This is related with a synergetic effect of Cu and the oxygen vacancies at the Cu-Support interface. The RWGS reaction carried out at atmospheric pressure using a CO2/H2/N2=1/3/1 reactant mixture over the CuZn3GaZr, resulted in a CO selectivity close to 100% at 325 °C under a CO2 conversion of 16.8%. The apparent Ea determined in the 275-325 °C range for CO production over CuZn3GaZr catalyst was 70.9±3.7 kJ/mol. On the other hand, new MoxC-based catalysts were prepared using sol-gel routes with different carbon precursors and without additional H2 and/or CH4 reducing thermal treatment. Bulk MoxC catalysts (MoxC-U, MoxC-CA and MoxC-E), gamma-Al2O3-, TiO2-, SBA-15- and SiO2-supported MoxC-U catalysts and, Cu- and Co-modified MoxC-U and MoxC/gamma-Al2O3 catalysts have been studied in the RWGS (CO2/H2/N2=1/3/1 and CO2/H2/N2=1/3/1) reaction in the 275-400 °C range and atmospheric pressure. MoxC-CA having hcp-Mo2C, fcc-Mo2C and/or fcc-MoC and the highest SBET (14.5 m2/g) showed the best performance. A CO yield of 41.8 mol/Kgcat·h, with 98% selectivity to CO was obtained at 400 °C using a CO2/H2/N2=1/3/1 mixture. The apparent Ea determined in the 275-325 °C range for CO production was 64.8+/-4.1 kJ/mol. MoxC-U showed only the presence of polycrystalline hcp-Mo2C. Its characteristics and catalytic properties were deeply analyzed and successfully interpreted in the light of theoretical studies carried out under a collaborative work. The adsorption heat of CO2 on MoxC-U was -3.2 eV. Over hcp-Mo2C, CO2 dissociates at 35 °C to CO+O surface species. Under RWGS conditions, the reaction proceeded by subsequent hydrogenation, and CO and H2O formation. Over MoxC-U, using a CO2/H2/N2=1/1/3 reactant mixture, the CO selectivity at 400 °C, 0.1 MPa, was 99.5% (CO2 conversion=16%). An apparent Ea of 55.2+/- 2.3 kJ/mol for CO production was determined for this catalyst in the 275-325 °C range. Different MoxC phases were obtained in gamma-Al2O3-, TiO2-, SBA-15- and SiO2-supported MoxC-U catalysts as a function of the support. In general, for supported MoxC catalysts, a higher CO production (mol CO/mol Mo·h) when compared with that of MoxC-U was found. 25MoxC/SiO2 catalyst, which showed the presence of hcp-Mo2C and fcc-MoC, was the most performant for CO production; it produced 17.0 mol CO/mol Mo·h at 400 °C, 0.1 MPa and CO2/H2/N2=1/3/1. Using a CO2/H2/N2=1/1/3 reaction mixture, the CO yield was up to 5 times higher than that obtained over the bulk MoxC-U catalyst.

Author: Abdulaziz Alamer
Publisher:
ISBN:
Category :
Languages : en
Pages : 39

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In recent decades, the world has been concerned about the environmental impact of CO2 emissions into the atmosphere. Thus, researchers have been focusing on enhancing current technologies, such as the Reverse Water Gas Shift (RWGS) reaction, to convert CO2 to synthetic fuels. The goal of this research was to develop a catalyst that has a high CO2 conversion and CO selectivity. To achieve this goal, different experiments were conducted at the same conditions to study the effect of different supports, metal loadings and different metals. All the experimental results were compared to equilibrium data obtained from Aspen Plus. Each tested catalyst was analyzed by BET and XRD to understand its physical and chemical structure as well as its behavior. Best catalyst was identified to be 5 wt% Cu supported on MgO, which achieved 20% CO2 conversion, 84% of Equilibrium CO2 conversion, and 75% CO selectivity.

Author: Inamuddin
Publisher: Springer Nature
ISBN: 3030286223
Category : Science
Languages : en
Pages : 216

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This book presents the catalytic conversion of carbon dioxide into various hydrocarbons and other products using photochemical, electrochemical and thermo-chemical processes. Products include formate, formic acid, alcohols, lower and higher hydrocarbons, gases such as hydrogen, carbon monoxide and syngas.

Author: Farhang Abdollahi
Publisher:
ISBN:
Category : University of Ottawa theses
Languages : en
Pages :

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In this research project, adsorption is considered in conjunction with the reverse water gas shift reaction in order to convert CO2 to CO for synthetic fuel production. If the CO2 for this process can be captured from high emitting industries it can be a very good alternative for reduced fossil fuel consumption and GHG emission mitigation. CO as an active gas could be used in Fischer-Tropsch process to produce conventional fuels. Literature review and process simulation were carried out in order to determine the best operating conditions for reverse water gas shift (RWGS) reaction. Increasing CO2 conversion to CO requires CO2/CO separation downstream of the reactor and recycling unreacted CO2 and H2 back into the reactor. Adsorption as a viable and cost effective process for gas separation was chosen for the CO2/CO separation. This was started by a series of adsorbent screening experiments to select the best adsorbent for the application. Screening study was performed by comparing pure gas isotherms for CO2 and CO at different temperatures and pressures. Then experimental isotherm data were modeled by the Temperature-Dependent Toth isotherm model which provided satisfactory fits for these isotherms. Henry law's constant, isosteric heat of adsorption and binary mixture prediction were determined as well as selectivity for each adsorbent. Finally, the expected working capacity was calculated in order to find the best candidate in terms of adsorption and desorption. Zeolite NaY was selected as the best candidate for CO2/CO separation in adsorption process for this project. In the last step breakthrough experiments were performed to evaluate operating condition and adsorption capacity for real multi component mixture of CO2, CO, H2 in both cases of saturated with water and dry gas basis. In multi components experiments zeolite NaY has shown very good performance to separate CO2/CO at low adsorption pressure and ambient temperature. Also desorption experiment was carried out in order to evaluate the working capacity of the adsorbent for using in industrial scale and eventually temperature swing adsorption (TSA) process worked very well for the regeneration step. Integrated adsorption system downstream of RWGS reactor can enhance the conversion of CO2 to CO in this process significantly resulting to provide synthetic gas for synthetic fuel production as well as GHG emission mitigation.

Author: Christopher Panaritis
Publisher:
ISBN:
Category :
Languages : en
Pages :

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The continued release of fossil-fuel derived carbon dioxide (CO2) emissions into our atmosphere led humanity into a climate and ecological crisis. Converting CO2 into valuable chemicals and fuels will replace and diminish the need for fossil fuel-derived products. Through the use of a catalyst, CO2 can be transformed into a commodity chemical by the reverse water gas shift (RWGS) reaction, where CO2 reacts with renewable hydrogen (H2) to form carbon monoxide (CO). CO then acts as the source molecule in the Fischer-Tropsch (FT) synthesis to form a range of hydrocarbons to manufacture chemicals and fuels. While the FT synthesis is a mature process, the conversion of CO2 into CO has yet to be made commercially available due to the constraints associated with high reaction temperature and catalytic stability. Noble metal ruthenium (Ru) has been widely used for the RWGS reaction due to its high catalytic activity, however, several constraints hinder its practical use, associated with its high cost and its susceptibility to deactivation. The doping or bimetallic use of non-noble metals iron (Fe) and cobalt (Co) is an attractive option to lower material cost and tailor the selectivity of the CO2 conversion towards the RWGS reaction without compromising catalytic activity. Furthermore, employing nanostructured catalysts as nanoparticles is a viable solution to further lower the amount of metal used and utilize the highly active surface area of the catalyst. Dispersing nanoparticles on ionically conductive supports/solid electrolytes which contain species like O2−, H+, Na+, and K+, provide an approach to further enhance the reaction. This phenomenon is referred to as metal-support interaction (MSI), allowing for the ions to back spillover from the support and onto the catalyst surface. An in-situ approach referred to as Non-Faradaic Modification of catalytic activity (NEMCA), also known as electrochemical promotion of catalysis (EPOC) is used to in-situ control the movement of ionic species from the solid electrolyte to and away from the catalyst. Both the MSI and EPOC phenomena have been shown to be functionally equivalent, meaning the ionic species act to alter the work function of the catalyst by forming an effective neutral double layer on the surface, which in turn alters the binding energy of the reactant and intermediate species to promote the reaction. The main objective of this work is to develop a catalyst that is highly active and selective to the RWGS reaction at low temperatures (

Author: Peter M. Maitlis
Publisher: John Wiley & Sons
ISBN: 3527656855
Category : Science
Languages : en
Pages : 404

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Greener Fischer-Tropsch Processes How can we use our carbon-based resources in the most responsible manner? How can we most efficiently transform natural gas, coal, or biomass into diesel, jet fuel or gasoline to drive our machines? The Big Questions today are energy-related, and the Fischer-Tropsch process provides industrially tested solutions. This book offers a comprehensive and up-to-date overview of the Fischer-Tropsch process, from the basic science and engineering to commercial issues. It covers industrial, economic, environmental, and fundamental aspects, with a specific focus on “green” concepts such as sustainability, process improvement, waste-reduction, and environmental care. The result is a practical reference for researchers, engineers, and financial analysts working in the energy sector, who are interested in carbon conversion, fuel processing or synthetic fuel technologies. It is also an ideal introductory book on the Fischer-Tropsch process for graduate courses in chemistry and chemical engineering.

Author: Tomas Ramirez Reina
Publisher: John Wiley & Sons
ISBN: 3527346503
Category : Technology & Engineering
Languages : en
Pages : 496

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A comprehensive guide that offers a review of the current technologies that tackle CO2 emissions The race to reduce CO2 emissions continues to be an urgent global challenge. "Engineering Solutions for CO2 Conversion" offers a thorough guide to the most current technologies designed to mitigate CO2 emissions ranging from CO2 capture to CO2 utilization approaches. With contributions from an international panel representing a wide range of expertise, this book contains a multidisciplinary toolkit that covers the myriad aspects of CO2 conversion strategies. Comprehensive in scope, it explores the chemical, physical, engineering and economical facets of CO2 conversion. "Engineering Solutions for CO2 Conversion" explores a broad range of topics including linking CFD and process simulations, membranes technologies for efficient CO2 capture-conversion, biogas sweetening technologies, plasma-assisted conversion of CO2, and much more. This important resource: * Addresses a pressing concern of global environmental damage, caused by the greenhouse gases emissions from fossil fuels * Contains a review of the most current developments on the various aspects of CO2 capture and utilization strategies * Incldues information on chemical, physical, engineering and economical facets of CO2 capture and utilization * Offers in-depth insight into materials design, processing characterization, and computer modeling with respect to CO2 capture and conversion Written for catalytic chemists, electrochemists, process engineers, chemical engineers, chemists in industry, photochemists, environmental chemists, theoretical chemists, environmental officers, "Engineering Solutions for CO2 Conversion" provides the most current and expert information on the many aspects and challenges of CO2 conversion.

Author: Faisal Mohamed Khan
Publisher:
ISBN:
Category : Carbides
Languages : en
Pages : 60

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The conversion of carbon dioxide (CO2) to synthetic fuels and chemicals is seen as a promising approach for reducing greenhouse gas emissions. Syngas (a mixture of CO and H2) that can be obtained from CO2 via the reverse water gas shift (RWGS) reaction can be further processed through the Fischer Tropsch process to produce higher hydrocarbons. Synthetic natural gas (CH4) produced from the Sabatier reaction can help reducing consumption of fossil fuel and also can serve as an energy reservoir for renewable electricity via power-to-gas. However, utilization of the abovementioned reaction pathways is still limited due to various challenges including catalyst activity, selectivity, and stability. This thesis focuses on the development of catalytic materials for the RWGS and Sabatier reactions. The first part of this thesis first focuses on a literature overview of recent developments in CO2 conversion through the RWGS and Sabatier reaction. Then, the experimental setup, catalyst synthesis procedures, catalytic performance evaluation, and characterization techniques are outlined. The second part discusses the results of the two transition metal carbides tested, namely molybdenum carbide (Mo2C) and cobalt carbide (Co2C). The catalytic performance of these catalysts was evaluated as a function of operation parameters for different synthesis procedures. The mechanisms of catalytic reactions are postulated and catalyst characterization results are provided. To briefly outline the most important findings, the Mo2C catalyst showed nearly complete selectivity towards CO formation at all temperatures tested, whereas the Co2C catalyst appeared to be highly selective towards CH4 formation. The performance of the corresponding metal oxides are also evaluated to evaluate the effect of carburization on the performance of the catalyst. The transitions metal oxides of molybdenum and cobalt both showed a substantial improvement in both conversion and selectivity after the carburization process. The performance of the catalysts supported on Al2O3 at a 1:4 metal-to-support basis was also analyzed. During the stability tests of supported catalysts, CO2 conversions of 84% and 74% were recorded over the Mo2C and Co2C catalysts, respectively, with a negligible drop in catalytic performance after 42 and 64 h time on stream.

Author: Guoliang Zhang
Publisher: Springer Nature
ISBN: 9819988225
Category :
Languages : en
Pages : 315

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