Download or read book Investigation of Reactions of Complex Epoxides on Silver 110 written by Adrienne Claire Lukaski and published by ProQuest. This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Direct oxidation processes, such as ethylene epoxidation to ethylene oxide, have been researched extensively due to the uniqueness of this process and to the commercial significance of the epoxide product. Despite the importance of epoxide production, the mechanistic details of olefin epoxidation remained obscure until recently and the majority of significant advances in Ag catalyst development occurred primarily through empirical methods. Recent surface science studies of ethylene oxide on Ag(111) have identified an oxametallacycle as the active intermediate in ethylene epoxidation; expansion of the epoxide ring to incorporate surface silver atoms forms the oxametallacycle species. Oxametallacycles have been isolated by ring-opening ethylene oxide on Ag(111) and Ag(110), 1-epoxy-3-butene on Ag(111) and Ag(110), styrene oxide on Ag(111) and Ag(110) and isoprene oxide and propylene oxide on Ag(110). Surface science techniques and Density Functional Theory (DFT) were used in this study to investigate the interactions of styrene oxide and isoprene oxide with the Ag(110) surface, as well as the interactions of ethylene oxide and propylene oxide with the clean and O-covered Ag(110) surfaces. TPD experiments demonstrate that the styrene oxide ring opens at the substituted carbon, and DFT calculations indicate that the phenyl ring of the resulting oxametallacycle is oriented nearly parallel to the Ag(110) surface. Interaction of the phenyl group with the silver surface stabilizes this intermediate relative to that derived from the mono-olefin epoxide, ethylene oxide. During TPD, the oxametallacycle undergoes ring closure to reform styrene oxide and isomerization to phenylacetaldehyde at 505 K on Ag(110). Styrene oxide-derived oxametallacycles exhibit similar ring-closure behavior on the Ag(111) surface. Isoprene oxide also forms a strongly bound oxametallacycle intermediate on the Ag(110) surface. The oxametallacycle undergoes ring-closure to reform isoprene oxide in two peaks at 320 and 460 K when synthesized by epoxide adsorption at low temperatures. Epoxide doses at higher surface temperatures (ca. 300 K) lead to isomerization of the oxametallacycle and desorption of the aldehyde isomer, 2-methyl-2-butenal, in a single peak at 460 K. This work represents the first demonstration of a surface oxametallacycle species derived from an allylic epoxide. Similar to oxametallacycles derived from the non-allylic epoxides, isoprene oxide ring opens at the carbon bound to the unsaturated vinyl and methyl substituent groups to form a linear oxametallacycle on the Ag(110) surface. The structure of the isoprene oxide-derived oxametallacycle resembles that formed from ring-opening its non-allylic counterpart, 1-epoxy-3-butene, on Ag(110), according to DFT calculations. Following adsorption at 250 K on both clean and O-covered Ag(110), ethylene oxide ring-opens to form a stable oxametallacycle. On the clean Ag(110) surface, the oxametallacycle reacts to reform the parent epoxide at 280 K during TPD, while the aldehyde isomer, acetaldehyde, is observed at higher oxametallacycle coverages. In the presence of coadsorbed oxygen atoms, a portion of the oxametallacycles dissociate to release ethylene. However, of those that react to form oxygen-containing products, the fraction forming ethylene oxide is similar to that on the clean surface. The acetaldehyde product of oxametallacycle reactions combusts via formation of acetate species; the acetates react to form CO 2 at temperatures as low as 360 K on the O-covered surface. No evidence was observed for other combustion channels. This work provides experimental evidence for the connection of oxametallacycles to combustion via acetaldehyde formation, as well as to ring-closure to form ethylene oxide. Adsorption of propylene oxide at 120 K with subsequent flash of the surface to 230 K prior to TPD leads to the formation of a stable oxametallacycle on both the clean and O-covered Ag(110) surfaces; the oxametallacycle then undergoes ring-closure to reform propylene oxide at 250 K during TPD. The selectivity to propylene oxide decreases at higher oxametallacycle coverages where acetone and allyl alcohol are formed; carbon dioxide is also formed near 250, 350, and 450 K from reactions of the oxametallacycle and its products on the O-covered surface. At higher oxametallacycle coverages, additional higher temperature desorptions are observed at 300 and 400 K; the product distributions in these peaks are the same as that in the 250 K peak. Similar to reactions of ethylene oxide on the O-covered Ag(110) surface, the same fraction of oxametallacycle species reacts to form propylene oxide in the presence of co-adsorbed oxygen as that on the clean surface, although the coverage of oxametallacycles is 10-20% higher on the O-covered surface. The principal effects of co-adsorbed oxygen are to increase the capacity of the surface and to open an additional combustion pathway to CO 2 . The oxametallacycle undergoes combustion through a propionaldehyde species. This work represents the first time that an oxametallacycle has been linked to propylene oxide production.
Download or read book Higher Olefin Epoxidation on Silver written by Michael C. N. Enever and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: An obvious and important goal in catalysis research is the design of new catalytic materials for current and new processes. A major step toward a rational approach is the comprehension of the fundamental mechanisms by which catalysts enhance specific reaction rates. One of the most important classes of reactions where little is understood of the reaction mechanism is heterogeneous olefin epoxidation. To date, only two epoxides can be produced via direct heterogeneous processes: ethylene oxide (EO) and 1-epoxy-3-butene (EpB). Heterogeneous ethylene oxide production has been an important chemical process for over fifty years, but the fundamental reaction mechanism has only recently been discovered. The production of EpB from 1,3-butadiene in this fashion has only recently been commercialized; however, this has invigorated interest in the area of heterogeneous olefin epoxidation, which is undeveloped as a whole. The primary aim of this research has been to obtain a better molecular-level understanding of surface reactions and intermediate species important to heterogeneous olefin epoxidation chemistry. To gain this understanding, a combined approach of surface science experimentation and ab initio quantum chemical calculations has been utilized to study the intermediate species formed on silver crystal surfaces and their reactions. This approach has proven invaluable in the study of ethylene oxide interacting with the Ag(111) surface. The work in this dissertation focused on the study of other epoxides interacting with silver surfaces to extend the knowledge and understanding of epoxidation chemistry beyond ethylene oxide, the simplest epoxide species. In particular, a link was established in prior work between oxametallacycle structures on silver and ethylene epoxidation. The combined experimental and theoretical approach was used to determine the role of these intermediates in the formation of 1-epoxy-3-butene, styrene oxide, and isobutylene oxide. Oxametallacycle intermediates---cyclic species defined by an -O-C-C- ring structure bonded at both ends to the silver surface---have been suggested as important intermediates in a number of reactions, but have been positively identified in only a few cases. By studying the formation of these species and their reactions, a greater understanding of their importance in olefin epoxidation chemistry has been obtained. Through the understanding of intermediates derived from these epoxide species in relation to ethylene epoxidation, some insight into a generalized oxametallacycle reaction framework on the Ag(111) surface was obtained. (Abstract shortened by UMI.).
Download or read book Progress in Inorganic Chemistry Volume 56 written by Kenneth D. Karlin and published by John Wiley & Sons. This book was released on 2009-02-23 with total page 596 pages. Available in PDF, EPUB and Kindle. Book excerpt: This series provides inorganic chemists and materials scientists with a forum for critical, authoritative evaluations of advances in every area of the discipline. Volume 56 continues to report recent advances with a significant, up-to-date selection of contributions by internationally-recognized researchers.
Download or read book Metals Abstracts written by and published by . This book was released on 1992 with total page 1516 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Nanostructured Catalysts written by Christian Hess and published by Royal Society of Chemistry. This book was released on 2011-07-22 with total page 453 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book gives a comprehensive up-to-date summary of the existing information on the structural/electronic properties, chemistry and catalytic properties of vanadium and molybdenum containing catalysts. It discusses the importance of nanoscience for the controlled synthesis of catalysts with functional properties and introduces the necessary background regarding surface properties and preparation techniques, leading from a textbook level to the current state of knowledge. Then follows an extensive survey and analysis of the existing open and patent literature - an essential knowledge source for the development of the new generation of partial oxidation catalysts. Important examples from current research on partial oxidation reactions are reviewed from experts in the field. The next chapter discusses the importance of 2- and 3-dimensional model systems for a fundamental understanding of the structure of transition metal oxide catalysts and its correlation to reactivity. Finally, an outlook on research opportunities within the area of partial oxidation reactions is presented.
Download or read book Faculties Publications and Doctoral Theses in Chemistry and Chemical Engineering at United States Universities written by American Chemical Society. Committee on Professional Training and published by . This book was released on 1991 with total page 1646 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Organic Reaction Mechanisms 2006 written by A. C. Knipe and published by John Wiley & Sons. This book was released on 2010-04-20 with total page 602 pages. Available in PDF, EPUB and Kindle. Book excerpt: Organic Reaction Mechanisms 2006 is the 42nd volume in this classical series. Every year, an experienced team of authors compiles these reviews, so that the reader can rely on a continuing quality of selection and presentation. Detailed author and subject indexes help the reader to find the information they are looking for. As a new service to the reader, all reaction mechanisms leading to stereospecific products are highlighted. This reflects the interest of synthetic organic chemists in such reactions and the pharmaceutical role of chiral molecules.
Download or read book March s Advanced Organic Chemistry written by Michael B. Smith and published by John Wiley & Sons. This book was released on 2007-01-29 with total page 2379 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Sixth Edition of a classic in organic chemistry continues its tradition of excellence Now in its sixth edition, March's Advanced Organic Chemistry remains the gold standard in organic chemistry. Throughout its six editions, students and chemists from around the world have relied on it as an essential resource for planning and executing synthetic reactions. The Sixth Edition brings the text completely current with the most recent organic reactions. In addition, the references have been updated to enable readers to find the latest primary and review literature with ease. New features include: More than 25,000 references to the literature to facilitate further research Revised mechanisms, where required, that explain concepts in clear modern terms Revisions and updates to each chapter to bring them all fully up to date with the latest reactions and discoveries A revised Appendix B to facilitate correlating chapter sections with synthetic transformations
Download or read book Understanding the Partial Oxidation of Propylene Over Silver Catalysts written by Jeffrey Taylor Ranney and published by . This book was released on 1998 with total page 382 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Energy Research Abstracts written by and published by . This book was released on 1988 with total page 1472 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Summaries of FY Research in the Chemical Sciences written by and published by . This book was released on 1995 with total page 176 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 700 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.
Download or read book General Science Index written by and published by . This book was released on 1989 with total page 1782 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Catalysis written by Matthias Beller and published by Wiley-VCH. This book was released on 2012-09-24 with total page 664 pages. Available in PDF, EPUB and Kindle. Book excerpt: Catalysis has revolutionized the chemical industry as catalysts are used in the production of most chemicals, resulting in a multi-billion euro business. This advanced textbook is a must-have for all Master and PhD students in the field as it adopts a unique interdisciplinary approach to the topic of catalysis. It presents a collection of chapters that explain the fundamentals of catalysis as the area has developed over the past decades and introduces new catalytic systems that are of becoming of increasing current importance. It covers all the essential principles, ranging from catalytic processes at the molecular level to catalytic reactor design and includes several case studies illustrating the importance of catalysts in the chemical industry.
Download or read book Ruthenium written by Hitoshi Ishida and published by BoD – Books on Demand. This book was released on 2022-01-26 with total page 228 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ruthenium is a precious metal not widely known to non-scientists. It is a target of much research, however. It is used in computer hard drives, the tips of fountain pens, and as a catalyst to purify car exhaust, among other uses. This book presents information and research on the properties and applications of ruthenium, including potential uses in phytochemical functions and anticancer activity.
Download or read book Kinetics of Heterogeneous Catalytic Reactions written by Michel Boudart and published by Princeton University Press. This book was released on 2014-07-14 with total page 241 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is a critical account of the principles of the kinetics of heterogeneous catalytic reactions in the light of recent developments in surface science and catalysis science. Originally published in 1984. The Princeton Legacy Library uses the latest print-on-demand technology to again make available previously out-of-print books from the distinguished backlist of Princeton University Press. These editions preserve the original texts of these important books while presenting them in durable paperback and hardcover editions. The goal of the Princeton Legacy Library is to vastly increase access to the rich scholarly heritage found in the thousands of books published by Princeton University Press since its founding in 1905.
Download or read book Alkenes written by Reza Davarnejad and published by BoD – Books on Demand. This book was released on 2018-02-07 with total page 182 pages. Available in PDF, EPUB and Kindle. Book excerpt: In organic chemistry, Alkenes, also known as olefins, are the unsaturated hydrocarbons with the general formula of CnH2n that contains one or more carbon-carbon double bonds in their chemical structures (RC=CR'). The presence of this double bond allows alkenes to react in ways that alkanes cannot. Hence, alkenes find many diverse applications in industry. These compounds are widely used as initial materials in the synthesis of alcohols, plastics, lacquers, detergents, and fuels. The current book includes all knowledge and novel data according to the structure of alkenes, their novel synthesis methods, and their applications. In addition, manufacture, properties, and the use of polyalkenes are the other important topics that are covered in this book. These data are collected by the efforts and contributions of many authors and scientists from all over the globe, and all of us are ready to further improve the contents of this book as per the readers' comments.
