Author: Phathutshedzo Khangale
Publisher:
ISBN:
Category : Carbon dioxide
Languages : en
Pages : 149

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Book Description

Author: William Jefferson Boone
Publisher:
ISBN:
Category : Aluminum oxide
Languages : en
Pages : 850

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Book Description

Author: Abegail Tebogo Bopape
Publisher:
ISBN:
Category : Atomic emission spectroscopy
Languages : en
Pages : 79

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Book Description

Author: Debanjan Chakrabarti
Publisher:
ISBN:
Category : Pretroleum products
Languages : en
Pages : 228

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Book Description
The Fischer-Tropsch (FT) synthesis is an indirect feeds-to-liquids process to produce synthetic crude oil from any carbonaceous source such as coal, natural gas or biomass. The carbonaceous source is converted to synthesis gas by gasification or reforming, which then undergoes simultaneous polymerisation and hydrogenation steps to form the hydrocarbon and oxygenate rich synthetic crude oil or syncrude, which can be refined to obtain gasoline, diesel, jet fuels and petrochemicals just as obtained from conventional crude oil. This provides an alternate source of hydrocarbon rich transportation fuels at a time when conventional crude oil reserves are getting depleted and oil demand is increasing. The product formed from the FT reaction contains hydrocarbons and oxygenates ranging from C1 to over C80 or so, along with CO2. An ideal operation would lead to maximization of the naphtha (C5-C11) and distillate (C11-C22) fractions in the product, while decreasing the selectivity of methane, C2-C4 gases, CO2 and heavy waxes. This can be achieved either by improvements in reactor design, manipulating operating parameters, or by developments in catalyst design. However, an understanding of the reaction mechanism of the process is essential to properly exploit these techniques. In the nearly 90 years since its discovery, the process has been studied extensively and been commercialized successfully. However, there still exists a lack of clarity with respect to the reaction pathways and surface intermediates involved in the system of reactions. Thus, there exists no consensus on the reaction mechanism of the FT system. In this thesis, the mechanisms of the reactions in the cobalt as well as iron catalyst-based FT systems have been investigated by conducting experiments and correlating the interpretation of the results with experimental observations in the literature. Based on the derived mechanisms, kinetic expressions have also been derived to represent each FT system. A study of CO2 in the cobalt-alumina based FT system was conducted by means of periodic feeding studies and investigations involving 14CO2 co-feeding. It was found that the CO2 in the cobalt catalyst system was capable of forming an oxygen free carbon intermediate and short chain hydrocarbons directly, without first undergoing a reverse water gas shift reaction to form CO. This was found to be a secondary methane formation pathway on cobalt catalysts. Investigations with 13C 18O indicated the existence of two carbon pools on the cobalt catalyst, one a CHx surface species and the other an adsorbed CO species. The insertion of the adsorbed CO species onto the CHx species resulted in the formation of a C2 oxygenate intermediate, which could either be hydrogenated to terminate as alcohol, or undergo hydrogen assisted C-O dissociation to form the C2 hydrocarbon intermediate. The C2 hydrocarbon intermediate could be desorbed as ethylene or hydrogenated to ethane. This indicated that the chain growth step took place by the CO insertion mechanism. The alcohols and hydrocarbons were found to originate from a common parent chain. A main hydrocarbon formation reaction was found to be the same on cobalt as well as iron catalysts. However, there were differences in the secondary reactions involved in each catalyst system. The methane as well as methanol formation was found to be the result of parallel pathways on cobalt catalysts - one via the FT reaction pathway, and the second via a rapid hydrogenation of adsorbed CO and CO2. The second pathway was negligible on iron catalysts. However, iron catalysts are known to be water gas shift active, which leads to the formation of CO2. However, on cobalt catalysts, any CO2 formed is either the result of a disproportionation reaction of CO to form C surface species and CO2, or by dissociation of CO on the catalyst surface followed by recombination of the C and O species. It was also inferred that the C2+ intermediates were attached to the catalyst via the terminal and adjacent-to-terminal carbon atoms, with both these atoms being available for chain growth. This explained the negative deviations of the C2 species from the ASF trend as well as the branching behaviour observed in the hydrocarbon product. Based on the detailed mechanism, kinetic expressions were derived for fitting to experimental data.

Author: André Steynberg
Publisher: Elsevier
ISBN: 0080472796
Category : Technology & Engineering
Languages : en
Pages : 722

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Book Description
Fischer-Tropsch Technology is a unique book for its state-of-the-art approach to Fischer Tropsch (FT) technology. This book provides an explanation of the basic principles and terminology that are required to understand the application of FT technology. It also contains comprehensive references to patents and previous publications. As the first publication to focus on theory and application, it is a contemporary reference source for students studying chemistry and chemical engineering. Researchers and engineers active in the development of FT technology will also find this book an invaluable source of information. * Is the first publication to cover the theory and application for modern Fischer Tropsch technology * Contains comprehensive knowledge on all aspects relevant to the application of Fischer Tropsch technology* No other publication looks at past, present and future applications

Author: Hazel C. Anderson
Publisher:
ISBN:
Category : Fischer-Tropsch process
Languages : en
Pages : 564

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Book Description

Author: Annemie Bogaerts
Publisher: MDPI
ISBN: 3038977500
Category : Technology & Engineering
Languages : en
Pages : 248

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Book Description
Plasma catalysis is gaining increasing interest for various gas conversion applications, such as CO2 conversion into value-added chemicals and fuels, N2 fixation for the synthesis of NH3 or NOx, methane conversion into higher hydrocarbons or oxygenates. It is also widely used for air pollution control (e.g., VOC remediation). Plasma catalysis allows thermodynamically difficult reactions to proceed at ambient pressure and temperature, due to activation of the gas molecules by energetic electrons created in the plasma. However, plasma is very reactive but not selective, and thus a catalyst is needed to improve the selectivity. In spite of the growing interest in plasma catalysis, the underlying mechanisms of the (possible) synergy between plasma and catalyst are not yet fully understood. Indeed, plasma catalysis is quite complicated, as the plasma will affect the catalyst and vice versa. Moreover, due to the reactive plasma environment, the most suitable catalysts will probably be different from thermal catalysts. More research is needed to better understand the plasma–catalyst interactions, in order to further improve the applications.

Author: Marcello De De Falco
Publisher: Springer Science & Business Media
ISBN: 1447151194
Category : Business & Economics
Languages : en
Pages : 202

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Book Description
As the annual production of carbon Dioxide (CO2) reaches 30 billion tones, the growing issue of the greenhouse effect has triggered the development of technologies for CO2 sequestration, storage and use as a reactant. Collecting together the reports of the Congress at University of Rome (Campus Bio-medico) held 16th April 2012, CO2: A Valuable Source of Carbon presents and discusses promising technologies for the industrial exploitation of CO2. Divided into two parts, the current technology is evaluated and summarized before European and national projects are presented. The focus on CO2 recovery, particularly in value-added production, proposes applicable methods to develop sustainable practices and even to mitigate greenhouse gas emission from large-scale fossil fuels usage. Including current data and real-world examples, CO2: A valuable source of carbon provides students, engineers, researchers and industry professional with up-to-date material and potential areas for development and research.

Author: Chunshan Song
Publisher:
ISBN:
Category : Science
Languages : en
Pages : 432

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Book Description
When chemical reagents are combined some of the reagents remain unmixed when the reaction is complete. Catalysts can reduce the amount of unmixed reagents, making the reaction more efficient, and the shape of the catalyst can be an important consideration. This volume surveys the field and collects new research on both experimental and theoretical aspects of shape-selective catalysis and catalytic materials.

Author: Wilson D. Shafer
Publisher: MDPI
ISBN: 303928388X
Category : Science
Languages : en
Pages : 414

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Book Description
Since the turn of the last century when the field of catalysis was born, iron and cobalt have been key players in numerous catalysis processes. These metals, due to their ability to activate CO and CH, haev a major economic impact worldwide. Several industrial processes and synthetic routes use these metals: biomass-to-liquids (BTL), coal-to-liquids (CTL), natural gas-to-liquids (GTL), water-gas-shift, alcohol synthesis, alcohol steam reforming, polymerization processes, cross-coupling reactions, and photocatalyst activated reactions. A vast number of materials are produced from these processes, including oil, lubricants, waxes, diesel and jet fuels, hydrogen (e.g., fuel cell applications), gasoline, rubbers, plastics, alcohols, pharmaceuticals, agrochemicals, feed-stock chemicals, and other alternative materials. However, given the true complexities of the variables involved in these processes, many key mechanistic issues are still not fully defined or understood. This Special Issue of Catalysis will be a collaborative effort to combine current catalysis research on these metals from experimental and theoretical perspectives on both heterogeneous and homogeneous catalysts. We welcome contributions from the catalysis community on catalyst characterization, kinetics, reaction mechanism, reactor development, theoretical modeling, and surface science.