Novel Magnetically Recyclable MoS2 Catalysts for Hydrodesulfurization and Hydrodeoxygenation PDF Download
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Author: Seyyedmajid Sharifvaghefi
Publisher:
ISBN:
Category : Desulfurization
Languages : en
Pages : 0
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Book Description
"Problems associated with hydrotreating of heavy and extra-heavy crude oils in conventional fixed-bed reactors have led to the design of more innovative reactors such as slurry reactors. Dispersed fine catalysts are commonly used in slurry reactors. However, separation of the fine particles with sizes in micrometers or nanometers from the liquid phase represents a challenge. In this work, novel magnetically recyclable catalysts are designed to address this issue. Two different magnetic core materials, Fe3O4 and Fe3S4, were studied. Core-and-shell composite catalysts MoS2/Fe3O4 and MoS2/Fe3S4 were designed. Both catalysts showed high activity in the hydrodesulfurization (HDS) of dibenzothiophene (DBT). Former one showed high affinity towards the direct desulfurization (DDS) pathway while the later one presented a balanced selectivity between DDS and hydrogenation (HYD) pathways. This provides the refineries an option to adjust the hydrotreating process based on their needs using each of the catalysts or a combination of both. Catalyst MoS2/Fe3S4 was further promoted by nickel and cobalt. The activity of the catalysts could be ranked as NiMoS/Fe3S4 > CoMoS/Fe3S4 > MoS2/Fe3S4. Addition of Ni to MoS2 catalyst forms the Ni-Mo-S phase with increased accessible sulfur edge which is responsible for the enhancement in both hydrogenation and desulfurization. The catalyst MoS2 with greigite core and its promoted catalyst NiMoS/CoMoS were also applied to the hydrodeoxygenation (HDO) of stearic acid. HDO was the dominant pathway for all of the catalysts. Catalysts MoS2/Fe3O4 and MoS2/Fe3S4 were used to investigate the roles of H2 and H2S and the involved active sites in the HDS of DBT. Two different active sites for hydrogenation (HYD) and hydrodesulfurization (HDS) were identified. The MoS2 with magnetite core demonstrated high selectivity towards the DDS pathway, which was attributable to the differences in adsorption energy of hydrogen and DBT over hydrogenation and desulfurization sites. H2S is favored being adsorbed on the S-edge vacancies to transfer the active sites to HYD/Isomerization sites. Hydrogen plays three distinctive roles: 1) When adsorbed at Mo edge, hydrogen promotes hydrogenation; 2) Strongly bonded at S-edge it accounts for direct desulfurization; 3) while loosely bonded to S-edge it favors HYD and isomerization."--Pages ii-iii.
Author: Seyyedmajid Sharifvaghefi
Publisher:
ISBN:
Category : Desulfurization
Languages : en
Pages : 0
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Book Description
"Problems associated with hydrotreating of heavy and extra-heavy crude oils in conventional fixed-bed reactors have led to the design of more innovative reactors such as slurry reactors. Dispersed fine catalysts are commonly used in slurry reactors. However, separation of the fine particles with sizes in micrometers or nanometers from the liquid phase represents a challenge. In this work, novel magnetically recyclable catalysts are designed to address this issue. Two different magnetic core materials, Fe3O4 and Fe3S4, were studied. Core-and-shell composite catalysts MoS2/Fe3O4 and MoS2/Fe3S4 were designed. Both catalysts showed high activity in the hydrodesulfurization (HDS) of dibenzothiophene (DBT). Former one showed high affinity towards the direct desulfurization (DDS) pathway while the later one presented a balanced selectivity between DDS and hydrogenation (HYD) pathways. This provides the refineries an option to adjust the hydrotreating process based on their needs using each of the catalysts or a combination of both. Catalyst MoS2/Fe3S4 was further promoted by nickel and cobalt. The activity of the catalysts could be ranked as NiMoS/Fe3S4 > CoMoS/Fe3S4 > MoS2/Fe3S4. Addition of Ni to MoS2 catalyst forms the Ni-Mo-S phase with increased accessible sulfur edge which is responsible for the enhancement in both hydrogenation and desulfurization. The catalyst MoS2 with greigite core and its promoted catalyst NiMoS/CoMoS were also applied to the hydrodeoxygenation (HDO) of stearic acid. HDO was the dominant pathway for all of the catalysts. Catalysts MoS2/Fe3O4 and MoS2/Fe3S4 were used to investigate the roles of H2 and H2S and the involved active sites in the HDS of DBT. Two different active sites for hydrogenation (HYD) and hydrodesulfurization (HDS) were identified. The MoS2 with magnetite core demonstrated high selectivity towards the DDS pathway, which was attributable to the differences in adsorption energy of hydrogen and DBT over hydrogenation and desulfurization sites. H2S is favored being adsorbed on the S-edge vacancies to transfer the active sites to HYD/Isomerization sites. Hydrogen plays three distinctive roles: 1) When adsorbed at Mo edge, hydrogen promotes hydrogenation; 2) Strongly bonded at S-edge it accounts for direct desulfurization; 3) while loosely bonded to S-edge it favors HYD and isomerization."--Pages ii-iii.
Author: Haiping Zhang
Publisher:
ISBN:
Category : Catalysts
Languages : en
Pages : 217
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Book Description
"The rigorous regulation on sulfur emission calls for newly designed catalysts with deep hydrodesulfurization capability. This has triggered a significant increase in research activities to seek suitable materials and synthesis techniques. Unsupported MoS2 becomes a good candidate as it possesses high catalytic activity and thermo stability. However, so far it is still a challenge to synthesize a dispersed MoS2 catalyst with low-cost precursors and simple methods. In this thesis, a novel hydrothermal method was developed using MoO3, Na2S, and HCl as precursors for the synthesis of unsupported MoS2. Several key factors that influence the catalyst synthesis and performance were carefully investigated, including the ratio of precursors, synthesis temperature, initial temperature, solvents, and promoters. Various characterization techniques, including XRD, TEM, SEM, XANES, EXAFS, Auto-sorb, TPR, microprobe analyzer, XPS, EDX, etc., were used to identify the crystalline structures of synthesized catalysts and to establish the relationship between their structures and hydrotreating activities. The hydrothermal synthesis method was successfully established. Results show that the weakly acidic medium is beneficial to the formation of MoS2. Proper MoO3/Na2S ratios lead to characteristics, such as nanocrystalline structure and large surface areas and pore volumes. Both the synthesis temperature and the initial temperature are key factors for the nucleation and growth of MoS2. A minimum synthesis temperature exists for the formation of crystalline structure, and high synthesis temperatures results in curved and shortened slabs. A high initial temperature benefits fast nucleation, thus leading to shorter slabs. Organic solvent (decalin) and supercritical heptane can dramatically change the aqueous environment. MoS2 slabs could be bent with the addition of decalin, and the curvature degree increases with the increase of decalin amounts. Supercritical heptane aids the creation of highly curved catalysts with better HDS performance (92.95% S conversion). The synthesized MoS2 catalysts were applied for the HDS of light cycle oil and for deoxygenation of waste cooking oil and canola oil to investigate the catalysis mechanisms. A new insight is proposed to distinguish the roles of promoters on deoxygenation pathways. NiMoS creates abundant sulfur vacancies that improve the hydrodeoxygenation, while CoMoS shows saturated edge sites in hydrogen atmosphere and facilitates the hydrodecarbon(x)ylation. From a kinetic model of deoxygenation process over CoMoS, it is found that direct hydrodecarbonylation of fatty acids dominates the hydrodecarbon(x)ylation routes; in the hydrodeoxygenation route, the reduction of fatty acids to alcohols is the rate limiting step in the production of C18 hydrocarbons from fatty acids."--Pages ii, iii.
Author: Mohammad Mansoob Khan
Publisher: Elsevier
ISBN: 0128209178
Category : Technology & Engineering
Languages : en
Pages : 378
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Book Description
Chalcogenide-Based Nanomaterials as Photocatalysts deals with the different types of chalcogenide-based photocatalytic reactions, covering the fundamental concepts of photocatalytic reactions involving chalcogenides for a range of energy and environmental applications. Sections focus on nanostructure control, synthesis methods, activity enhancement strategies, environmental applications, and perspectives of chalcogenide-based nanomaterials. The book offers guidelines for designing new chalcogenide-based nanoscale photocatalysts at low cost and high efficiency for efficient utilization of solar energy in the areas of energy production and environment remediation. - Provides information on the development of novel chalcogenide-based nanomaterials - Outlines the fundamentals of chalcogenides-based photocatalysis - Includes techniques for heterogeneous catalysis based on chalcogenide-based nanomaterials
Author: Th. Weber
Publisher: Springer Science & Business Media
ISBN: 9401735778
Category : Science
Languages : en
Pages : 357
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Book Description
Hydrotreating catalysis with transition metal sulphides is one of the most important areas of industrial heterogeneous catalysis. The present book deals with the chemical and catalytic aspects of transition metal sulphides, focusing on their use in hydrotreating catalysis. The book¿s 12 chapters present reviews of solid-state, coordination and organometallic chemistry, surface science and spectroscopic studies, quantum chemical calculations, catalytic studies with model and real catalysts, as well as refinery processes. A presentation of state-of-the-art background to pertinent work in the field. Can be used as an introduction to the chemical and catalytic properties of transition metal sulphides as well as an advanced level reference.
Author: Gian Paolo Chiusoli
Publisher: Royal Society of Chemistry
ISBN: 0854041508
Category : Education
Languages : en
Pages : 312
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Book Description
A definitive reference source, written by practising experts in the field, providing detailed and up-to-date information on key aspects of metal catalysis.
Author: Zeynep Ilsen Önsan
Publisher: John Wiley & Sons
ISBN: 1119248469
Category : Technology & Engineering
Languages : en
Pages : 399
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Book Description
Provides a holistic approach to multiphase catalytic reactors from their modeling and design to their applications in industrial manufacturing of chemicals Covers theoretical aspects and examples of fixed-bed, fluidized-bed, trickle-bed, slurry, monolith and microchannel reactors Includes chapters covering experimental techniques and practical guidelines for lab-scale testing of multiphase reactors Includes mathematical content focused on design equations and empirical relationships characterizing different multiphase reactor types together with an assortment of computational tools Involves detailed coverage of multiphase reactor applications such as Fischer-Tropsch synthesis, fuel processing for fuel cells, hydrotreating of oil fractions and biofuels processing
Author: Lisa M. Balbes
Publisher:
ISBN: 9780195183665
Category : Chemistry
Languages : en
Pages : 326
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Book Description
A Chemistry background prepares you for much more than just a laboratory career. The broad science education, analytical thinking, research methods, and other skills learned are of value to a wide variety of types of employers, and essential for a plethora of types of positions. Those who are interested in chemistry tend to have some similar personality traits and characteristics. By understanding your own personal values and interests, you can make informed decisions about what career paths to explore, and identify positions that match your needs. By expanding your options for not only what you will do, but also the environment in which you will do it, you can vastly increase the available employment opportunities, and increase the likelihood of finding enjoyable and lucrative employment. Each chapter in this book provides background information on a nontraditional field, including typical tasks, education or training requirements, and personal characteristics that make for a successful career in that field. Each chapter also contains detailed profiles of several chemists working in that field. The reader gets a true sense of what these people do on a daily basis, what in their background prepared them to move into this field, and what skills, personality, and knowledge are required to make a success of a career in this new field. Advice for people interested in moving into the field, and predictions for the future of that career, are also included from each person profiled. Career fields profiled include communication, chemical information, patents, sales and marketing, business development, regulatory affairs, public policy, safety, human resources, computers, and several others. Taken together, the career descriptions and real case histories provide a complete picture of each nontraditional career path, as well as valuable advice about how career transitions can be planned and successfully achieved by any chemist.
Author: Roberto Rinaldi
Publisher: Royal Society of Chemistry
ISBN: 1849738017
Category : Science
Languages : en
Pages : 324
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Book Description
As the biorefinery industry expands to meet the latest discoveries in biomass conversion, this book provides a thorough grounding in the subject.
Author: Julius Scherzer
Publisher: CRC Press
ISBN: 9780824797607
Category : Science
Languages : en
Pages : 330
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Book Description
Presents advances in the field of hydrocracking. The volume includes catalytic materials, reaction mechanisms and pathways, as well as hydrocracking processes and applications. It discusses hydrocracking processes and hydrocracking technology in catalytic dewaxing, resid upgrading, and fluid catalytic cracking feedstock improvement
Author: Melissa Kirschke Stockdale
Publisher: Cambridge University Press
ISBN: 1107093864
Category : History
Languages : en
Pages : 303
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Book Description
This study of Russian mobilization in the Great War explores how the war shaped national identity and conceptions of citizenship.
