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Author: Joseph Grant Publisher: ISBN: Category : Languages : en Pages : 108
Book Description
The recent surge in shale gas resources creates new opportunities to improve process efficiencies for the production of important chemical building blocks. Non-oxidative dehydrogenation of propane (PDH), the primary "on-purpose" propylene technology used worldwide today, has process inefficiencies that may be improved by co-feeding oxygen and propane to drive the oxidative dehydrogenation (ODH) of propane reaction. However, after decades of catalyst research for ODH of propane this reaction has yet to be commercialized due to the difficulty of controlling this partial oxidation to selectively yield propylene rather than the more-thermodynamically stable CO and CO2 (COx) products. This thesis explores the reactivity and properties of two very different classes of catalysts for the ODH of alkanes: 1) supported vanadia and 2) boron-containing catalysts. Supported vanadia catalysts, the most-studied catalyst for this transformation in the literature, show markedly higher selectivity to propylene when existing as dispersed two-dimensional metal oxide surface species. By introducing a small amount of Na+ to the surface of SiO2, the maximum two-dimensional surface density can be dramatically enhanced. This effect is proved using spectroscopic characterization, as well as the ODH of propane used as a probe reaction. Boron-containing compounds, especially boron nitride (BN) materials, were previously overlooked as catalysts for the ODH of alkanes, and rather deemed to be inert. On the contrary, these B-containing catalysts are now considered to be among the most-selective catalysts for the ODH of alkanes as a method to form their corresponding olefins. The rate of alkane consumption is dependent on oxygen adsorption to the catalyst surface, and shows second-order dependence in the concentration of the alkane. At these temperatures (400-500°C) oxygen adsorption to the B-containing catalyst only occurs when exposed to the ODH reaction (not only air or a combination of air and steam), and is verified with numerous spectroscopic techniques including X-ray Photoelectron Spectroscopy (XPS), and Attenuated Total Reflectance Infrared (ATR-IR). Recent work with X-ray Absorption Spectroscopy (XAS) and 11B MAS NMR dismisses the possibility that a potential B2O3 surface layer acts as the active site by revealing that B2O3 is not present on spent catalysts.
Author: Joseph Grant Publisher: ISBN: Category : Languages : en Pages : 108
Book Description
The recent surge in shale gas resources creates new opportunities to improve process efficiencies for the production of important chemical building blocks. Non-oxidative dehydrogenation of propane (PDH), the primary "on-purpose" propylene technology used worldwide today, has process inefficiencies that may be improved by co-feeding oxygen and propane to drive the oxidative dehydrogenation (ODH) of propane reaction. However, after decades of catalyst research for ODH of propane this reaction has yet to be commercialized due to the difficulty of controlling this partial oxidation to selectively yield propylene rather than the more-thermodynamically stable CO and CO2 (COx) products. This thesis explores the reactivity and properties of two very different classes of catalysts for the ODH of alkanes: 1) supported vanadia and 2) boron-containing catalysts. Supported vanadia catalysts, the most-studied catalyst for this transformation in the literature, show markedly higher selectivity to propylene when existing as dispersed two-dimensional metal oxide surface species. By introducing a small amount of Na+ to the surface of SiO2, the maximum two-dimensional surface density can be dramatically enhanced. This effect is proved using spectroscopic characterization, as well as the ODH of propane used as a probe reaction. Boron-containing compounds, especially boron nitride (BN) materials, were previously overlooked as catalysts for the ODH of alkanes, and rather deemed to be inert. On the contrary, these B-containing catalysts are now considered to be among the most-selective catalysts for the ODH of alkanes as a method to form their corresponding olefins. The rate of alkane consumption is dependent on oxygen adsorption to the catalyst surface, and shows second-order dependence in the concentration of the alkane. At these temperatures (400-500°C) oxygen adsorption to the B-containing catalyst only occurs when exposed to the ODH reaction (not only air or a combination of air and steam), and is verified with numerous spectroscopic techniques including X-ray Photoelectron Spectroscopy (XPS), and Attenuated Total Reflectance Infrared (ATR-IR). Recent work with X-ray Absorption Spectroscopy (XAS) and 11B MAS NMR dismisses the possibility that a potential B2O3 surface layer acts as the active site by revealing that B2O3 is not present on spent catalysts.
Author: Juan Mauricio Venegas Publisher: ISBN: Category : Languages : en Pages : 120
Book Description
Light olefins such as ethylene and propylene form the foundation of the modern chemical industry, with yearly production volumes well into the hundreds of millions of metric tons. Currently, these light olefins are mainly produced via energy-intensive steam cracking. Alternatively, oxidative dehydrogenation (ODH) of light alkanes to produce olefins allows for lower operation temperatures and extended catalyst lifetimes, providing valuable process efficiencies. This route has led to significant research interest due to the wide availability of natural gas from shale deposits. Advances in this area have still not yielded catalysts that are sufficiently selective to olefins for industrial implementation, and ODH still remains a holy grail of selective alkane oxidation research. Research into selective heterogeneous catalysts for the ODH of propane has led to the extensive use of vanadium oxide-based catalysts, and studies on the surface mechanism involved have been used to improve the catalytic activity of the material. Despite decades of research, however, selectivity towards propylene has not proven satisfactory at industrially-relevant conversions. In this thesis, I will present the serendipitous discovery and subsequent development of hexagonal boron nitride (hBN) and other boron-containing catalysts as selective ODH catalysts. Specifically, I will illustrate the evolution of our understanding of the chemical origin of the reactivity of these materials, which until our initial discovery were deemed chemically inert. By combining reactivity studies with spectroscopic characterization highlighted a unique interaction between boron and oxiygen that differs from that of metal oxides. This methodical characterization of catalytic activity and structural changes of hBN during ODH prompted us to zero in on oxidized boron species, not hBN itself, as the true catalyst of alkane oxidation. In turn, this discovery led us to describe a whole class of B-containing materials that share (and often improve upon) the catalytic performance of hBN. At this point, we decided to step away from material studies and instead improve our understanding on how the catalytic performance of hBN is affected by reactor operating parameters. In particular, we investigated the role of heat and mass transfer on catalytic performance. Unexpectedly, we were once again surprised by hBN when various experimental results during these efforts suggested the significance of gas phase chemistry on ODH performance. For example, we observed that upon dilution of hBN with an inert thermal conductor (to mitigate hotspot formation), the observed reactivity scales with total bed volume rather than hBN mass. Up until these studies, we expected all reactivity to stem from oxidized boron species, but these may be only a part of a more complex surface-gas phase reaction network. The final portion of this thesis presents our latest efforts to understand the role of each reactant on surface and gas phase reaction pathways. Within this work, we incorporate water into our reaction feeds to assess its influence as a source of gas phase radical species to carry out propane activation. Indeed, we observe significant rate enhancements by addition of water. This reactivity enhancement likely involves influencing reactive species concentrations primarily in the gas phase and, to a lesser extent, altering the surface composition during ODH. Overall, this thesis expands our understanding of B-based materials as ODH catalysts and highlights the importance of considering gas phase radical chemistry in future process development.
Author: Jacques C. Vedrine Publisher: Elsevier ISBN: 0128116323 Category : Technology & Engineering Languages : en Pages : 620
Book Description
Metal Oxides in Heterogeneous Catalysis is an overview of the past, present and future of heterogeneous catalysis using metal oxides catalysts. The book presents the historical, theoretical, and practical aspects of metal oxide-based heterogeneous catalysis. Metal Oxides in Heterogeneous Catalysis deals with fundamental information on heterogeneous catalysis, including reaction mechanisms and kinetics approaches.There is also a focus on the classification of metal oxides used as catalysts, preparation methods and touches on zeolites, mesoporous materials and Metal-organic frameworks (MOFs) in catalysis. It will touch on acid or base-type reactions, selective (partial) and total oxidation reactions, and enzymatic type reactions The book also touches heavily on the biomass applications of metal oxide catalysts and environmentally related/depollution reactions such as COVs elimination, DeNOx, and DeSOx. Finally, the book also deals with future trends and prospects in metal oxide-based heterogeneous catalysis. Presents case studies in each chapter that provide a focus on the industrial applications Includes fundamentals, key theories and practical applications of metal oxide-based heterogeneous catalysis in one comprehensive resource Edited, and contributed, by leading experts who provide perspectives on synthesis, characterization and applications
Author: Patricio Ruiz Publisher: Elsevier Science Limited ISBN: 9780444894663 Category : Science Languages : en Pages : 477
Book Description
This volume contains invited papers and communications presented at the Third European Workshop Meeting on Selective Oxidation by Heterogeneous Catalysis. The purpose of the meeting was to present recent results and to discuss new aspects of partial oxidation by heterogeneous catalysis. The following topics were discussed: Novel processes for obtaining new fine chemicals by catalytic partial oxidation; selective oxidation and oxidative dehydrogenation of alkanes; new catalysts and advances in preparation methods of oxidation catalysts; new phenomena in partial oxidation and new aspects of surface chemistry in oxide catalysts; new applications of physicochemical methods for characterization of oxide catalysts; oxidation with other agents than oxygen and catalytic oxidation of carbohydrates. This book will provide a valuable set of data on reactions of selective oxidation which will be extremely useful to catalyst and related practitioners, whether fundamentalists or highly applied, and to process engineers who wish to evaluate current findings in this field. The wide-range approach to reactions of selective oxidation will disseminate knowledge in specialized areas of selective oxidation and encourage innovation and creativity.
Author: Yue Hu Publisher: ISBN: Category : Languages : en Pages : 0
Book Description
In this dissertation, the development of heterogeneous catalysts are presented. In the first project, we report Ni/ZSM-5 as efficient hydrodeoxygenation catalysts for the selective hydrodeoxygenation of ketones, ethers, and phenols. In the second project, we report Co-PZ-TPAHAP as an efficient bidirectional-catalyst for reversible hydrogenation and oxidative dehydrogenation of N-heterocycles. In the third project, we developed a Ni-based catalyst supported on mesoporous silica. It allows for efficient hydrogenation of carbonyls, nitroarenes, N-heterocycles as well as alkenes and alkynes.eng
Author: Noritaka Mizuno Publisher: John Wiley & Sons ISBN: 3527627553 Category : Science Languages : en Pages : 356
Book Description
Filling a gap in the current literature, this comprehensive reference presents all important catalyst classes, including metal oxides, polyoxometalates, and zeolites. Readers will find here everything they need to know -- from structure design to characterization, and from immobilization to industrial processes. A true must-have for anyone working in this key technology.
Author: M. Absi-Halabi Publisher: Elsevier ISBN: 0080528694 Category : Technology & Engineering Languages : en Pages : 617
Book Description
Catalysis plays an increasingly critical role in modern petroleum refining and basic petrochemical industries as market demands for and specifications of petroleum and petrochemical products are continuously changing. As we enter the 21st century, new challenges for catalysis science and technology are anticipated in almost every field. Particularly, better utilization of petroleum resources and demands for cleaner transportation fuels are major items. It was against this background that the 2nd International Conference on Catalysts in Petroleum Refining and Petrochemical Industries was organized. The conference was attended by around 300 specialists in the catalysis field from both academia and industry from over 30 countries. It provided a forum for the exchange of ideas between scientists and engineers from the region with their counterparts from industrialized countries. The papers from the conference, which were carefully selected from around 100 submissions, were refereed in terms of scientific and technical content and format in accordance with internationally accepted standards. They comprise a mix of reviews providing an overview of selected areas, original fundamental research results, and industrial experiences.
Author: Pedro J. Pérez Publisher: Springer Science & Business Media ISBN: 9048136989 Category : Science Languages : en Pages : 277
Book Description
Over the past decade, much research effort has been devoted to the design and synthesis of new reagents and catalysts that can influence carbon-hydrogen bond activation, mainly because of the prospect that C−H activation could enable the conversion of cheap and abundant alkanes into valuable functionalized organic compounds. Alkane C-H Activation by Single-Site Metal Catalysis presents the current state-of-the-art development in the catalytic systems for the catalytic trans-formations of alkanes under homogeneous conditions. Chapter 1 offers a comprehensive summary of the main discoveries realized so far. Chapter 2 reviews the so-called electrophilic activation, initiated by Shulpín in the late 60s, and the base for the Catalytica system. Chapter 3 examines the catalytic borylation of alkanes, discovered by Hartwig, whereas chapter 4 provides an updated vision of the alkane dehydrogenation reaction. Chapter 5 covers the oxygenation of C-H bonds, a field of enormous interest with bioinorganic im-plications, and finally chapter 6 presents the functionalization of alkane C-H bonds by carbene or nitrene insertion. The history of C-H bond activation, and the current research described in this book, highlight the current research and present the reader with an outlook of this field which continues to be explored by an increasingly visionary and enthusiastic group of organic, organometallic, biological and physical chemists.
Author: Joseph Grant
Author: Joseph Grant
Author: Juan Mauricio Venegas
Author: Jacques C. Vedrine
Author: Derrick W. Flick
Author: Patricio Ruiz
Author: Yue Hu
Author: Noritaka Mizuno
Author: M. Absi-Halabi
Author: Koen J. L. Linsen
Author: Pedro J. Pérez