Download or read book The Synthesis Characterization and Catalytic Applications of Heteropolyanion supported Rhodium I and Iridium I written by David John Edlund and published by . This book was released on 1987 with total page 622 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Synthesis Characterization and Catalytic Performance of Rhodium and Iridium Complexes Supported in Dealuminated HY Zeolite written by Claudia Martinez Macias and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Essentially molecular supported catalysts were synthesized by using organometallic complexes as precursors, such as Rh(CO)2(acac), Rh(C2H4)2(acac), Ir(CO)2(acac), and Ir(C2H4)2(acac) (where acac is acetylacetonate) and HY zeolite as a support. A goal was to obtain highly uniform solid catalysts with well-defined structures. Characterization by X-ray absorption (XAS) and infrared (IR) spectroscopies confirmed the anchoring of the metal to the support with a high degree of uniformity. IR and 29Si and 27Al nuclear magnetic resonance (NMR) spectra characterize the presence of amorphous regions in the zeolite, and scanning transmission electron microscopy (STEM) identifies these amorphous regions, where iridium is more susceptible to aggregation than in the crystalline regions. Treatment of Ir(CO)2/HY zeolite with C2H4 and H2 at room temperature led to a family of species which includes Ir(CO)2, Ir(CO)(C2H4), Ir(CO)(C2H4)2, Ir(CO)(C2H5) and, tentatively, Ir(CO)(H). The identification of the species is based on XAS and IR spectra (including spectra of samples made with isotopically labeled ligands, 13CO and D2O) and density functional theory (DFT) calculations. The catalytic performance of isostructural rhodium and iridium species incorporating CO as a ligand was measured for the ethylene conversion; the CO not only acts as an inhibitor but it also as a probe molecule providing information about the electronic properties of the metal and of the species present during reaction. When isostructural rhodium and iridium diethylene species are bonded near each other on HY zeolite, the iridium complexes alter the selectivity of rhodium by spilling over hydrogen that hinders the interaction between ethylene and the acidic sites of the zeolite that act in concert with the rhodium, causing it to favor ethylene hydrogenation over dimerization. All these results show how structurally simple solid catalysts can be used to facilitate fundamental understanding of catalysts and their performance.
Download or read book Supported Molecular Rhodium Complexes and Dimers written by Dicle Yardimci and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Solid catalysts incorporating transition metals are important in industry, providing cost- effective syntheses, ease of separation from products, and control of selectivity. The metal is often expensive and thus often constitutes only about one percent of the catalyst mass, being highly dispersed on a high-area support. Dispersed metals in industrial catalysts are usually highly nonuniform in structure and challenging to characterize, and consequently relationships between structure and catalyst performance are typically less than fully understood. Our approach to the investigation of supported metal catalysts involves the synthesis of uniform catalytic sites that have essentially molecular character. Supported molecular catalysts can be characterized spectroscopically to provide fundamental understanding of the catalyst structure under reactive atmospheres, and thereby determination of structural changes of working catalysts that can be correlated with the catalytic activity and selectivity. The sample characterization techniques used in this work included infrared (IR), extended X-ray absorption fine structure (EXAFS), and X-ray absorption near edge structure (XANES) spectroscopies, as well as gas chromatography (GC) and mass spectrometry (MS) to characterize reaction products. The catalysts were prepared from the organometallic precursor Rh(C2H4)2(C5H7O2) and the supports MgO and zeolite HY. These catalysts initially incorporated site-isolated, mononuclear rhodium complexes on the supports. The complexes on MgO were treated in H2 at elevated temperatures to form the smallest supported rhodium clusters--rhodium dimers. These catalysts are essentially molecular in character and allowed tailoring of the rhodium nuclearity, the ligands bonded to the rhodium, and the rhodium-support interface. The catalysts incorporated mononuclear Rh(C2H4)2 and Rh(CO)2 complexes; dimeric rhodium clusters with ethyl ligands, and dimeric rhodium clusters with CO ligands. These were tested for the hydrogenation of ethylene. Rhodium in various forms is highly active for catalytic hydrogenation of olefins. However, rhodium has been little investigated for diene hydrogenation, because, like other noble metals in the form of supported clusters or particles, it is unselective. We postulated that new catalytic chemistry of rhodium could emerge if the catalytic species were essentially molecular so that they could be tuned by the choice of the rhodium nuclearity and ligands. Thus, we investigated the influence of the following catalyst design variables on the activity and selectivity of supported rhodium for 1,3-butadiene hydrogenation: (a) the metal nuclearity, ranging from one to several; (b) the electron-donor properties of the support (MgO vs. zeolite Y); and (c) other ligands on the rhodium, including reactive hydrocarbons (ethylene or ethyl) and CO. The data show that extremely small MgO-supported rhodium clusters that are partially carbonylated are highly active and selective for the hydrogenation of 1,3-butadiene to give n-butenes. The support, the rhodium nuclearity, and the ligands on rhodium are crucial to the catalyst selectivity, transforming a metal that is typically regarded as unselective for 1,3-butadiene hydrogenation into one that is highly selective even at high conversions. Transition metals in complexes and clusters tend to aggregate to form of more stable, bulk particles under reactive atmospheres, causing catalyst deactivation. We investigated the initial steps of the aggregation of supported metal species that were highly dispersed on MgO and zeolite HY, synthesizing samples that incorporated supported rhodium complexes bonded to ligands with different reactivities (including the support), and then spectroscopically investigated the formation of extremely small rhodium clusters in the presence of H2. The stability of the rhodium complexes and the stoichiometry of the surface-mediated transformations are regulated by the support and the other ligands bonded to the rhodium, being prompted at a lower temperature with zeolite HY than the better electron-donor MgO when the rhodium complexes incorporate ethylene ligands, but occurring more facilely on the MgO than on the zeolite when the ligands are CO. The preparation of highly uniform rhodium dimers is possible. We infer that results such as those presented here may be useful in guiding the design of stable, highly dispersed supported metal catalysts by choice of the support and other ligands on the metal.
Download or read book Supported Molecular Rhodium Complexes and Clusters written by Ann Jia-Bao Liang and published by . This book was released on 2008 with total page 754 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Synthesis and Characterization of Supported Organometallic Rhodium I Catalysts written by Donald Nilan Marquardt and published by . This book was released on 1974 with total page 252 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Rhodium Catalyzed Hydroformylation written by Piet W.N.M. van Leeuwen and published by Springer Science & Business Media. This book was released on 2006-04-11 with total page 291 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the last decade there have been numerous advances in the area of rhodium-catalyzed hydroformylation, such as highly selective catalysts of industrial importance, new insights into mechanisms of the reaction, very selective asymmetric catalysts, in situ characterization and application to organic synthesis. The views on hydroformylation which still prevail in the current textbooks have become obsolete in several respects. Therefore, it was felt timely to collect these advances in a book. The book contains a series of chapters discussing several rhodium systems arranged according to ligand type, including asymmetric ligands, a chapter on applications in organic chemistry, a chapter on modern processes and separations, and a chapter on catalyst preparation and laboratory techniques. This book concentrates on highlights, rather than a concise review mentioning all articles in just one line. The book aims at an audience of advanced students, experts in the field, and scientists from related fields. The didactic approach also makes it useful as a guide for an advanced course.
Download or read book Rhodium Based Mono and Bi metallic Nanoparticles written by Mahmoud Ibrahim and published by . This book was released on 2016 with total page 276 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this thesis, synthesis, characterization and catalytic applications of mono- and bi-metallic rhodium-based nanoparticles are reported. Rhodium has been chosen as a primary metal given its high interest in catalysis, mainly in hydrogenation and hydroformylation reactions. The synthesis of mono-metallic rhodium nanoparticles (NPs) is the core of this work. It was performed by decomposition of the organometallic complex [Rh(C3H5)3] in solution under dihydrogen pressure and in the presence of different stabilizers including ligands and polymers to control the growth of the particles. Selected nanoparticles were deposited on the surface of amino-functionalized magnetic silica as a support for recovery and recycling concerns in catalysis. Diverse bi-metallic nanoparticles have been also prepared in one-pot conditions by co-decomposition of the [Rh(C3H5)3] with other organometallic precursors including [Ni(cod)2], [Ru(cod)(cot)], [Pt(nor)3] and [Pd(dba)2]2. Tuning of the metal ratios between [Rh] and the second metal [M], or of the nature and the amount of the stabilizer used for the synthesis allowed to obtain nanoparticles of different sizes and chemical compositions. The characterization of the obtained nanoparticles was performed by using a combination of state-of-art techniques (TEM, HRTEM, STEM-EDX, ICP, WAXS, EXAFS, Xanes, XPS, NMR...). Surface studies were carried out in some cases, by adsorbing CO on the surface of the particles which was followed by spectroscopic techniques (FT-IR, NMR) to probe their surface state. Some of these nanoparticles were investigated in catalytic reactions, mainly hydrogenation with Rh NPs and hydrogenolysis for RhNiOx NPs. Both colloidal and supported catalytic studies were carried out in the case of hydrogenation catalysis. The originality of this work lies in the development of simple synthesis tools inspired from organometallic chemistry to get well-controlled rhodium-based nanoparticles in terms of size, size distribution, composition and surface state, all these parameters being important whatever the target application. The interest of the obtained nanoparticles in catalysis has been also evidenced in different reactions. This PhD work may open new opportunities of research both in nanochemistry and catalysis.
Download or read book Dissertation Abstracts International written by and published by . This book was released on 1988 with total page 884 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Rhodium Catalysis in Organic Synthesis written by Ken Tanaka and published by John Wiley & Sons. This book was released on 2019-05-06 with total page 684 pages. Available in PDF, EPUB and Kindle. Book excerpt: An essential reference to the highly effective reactions applied to modern organic synthesis Rhodium complexes are one of the most important transition metals for organic synthesis due to their ability to catalyze a variety of useful transformations. Rhodium Catalysis in Organic Synthesis explores the most recent progress and new developments in the field of catalytic cyclization reactions using rhodium(I) complexes and catalytic carbon-hydrogen bond activation reactions using rhodium(II) and rhodium(III) complexes. Edited by a noted expert in the field with contributions from a panel of leading international scientists, Rhodium Catalysis in Organic Synthesis presents the essential information in one comprehensive volume. Designed to be an accessible resource, the book is arranged by different reaction types. All the chapters provide insight into each transformation and include information on the history, selectivity, scope, mechanism, and application. In addition, the chapters offer a summary and outlook of each transformation. This important resource: -Offers a comprehensive review of how rhodium complexes catalyze a variety of highly useful reactions for organic synthesis (e.g. coupling reactions, CH-bond functionalization, hydroformylation, cyclization reactions and others) -Includes information on the most recent developments that contain a range of new, efficient, elegant, reliable and useful reactions -Presents a volume edited by one of the international leading scientists working in the field today -Contains the information that can be applied by researchers in academia and also professionals in pharmaceutical, agrochemical and fine chemical companies Written for academics and synthetic chemists working with organometallics, Rhodium Catalysis in Organic Synthesis contains the most recent information available on the developments and applications in the field of catalytic cyclization reactions using rhodium complexes.
Download or read book Iridium Complexes in Organic Synthesis written by Luis A. Oro and published by John Wiley & Sons. This book was released on 2008-12-03 with total page 424 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ranging from hydrogenation to hydroamination, cycloadditions and nanoparticles, this first handbook to comprehensively cover the topic of iridium in synthesis discusses the important advances in iridium-catalyzed reactions, namely the use of iridium complexes in enantioselective catalysis. A must for organic, complex and catalytic chemists, as well as those working with/on organometallics.
Download or read book Iridium Complexes with Cp Ligand written by Bi Jiang and published by . This book was released on 2010 with total page 101 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Catalysis by Polyoxometalate supported Atomically dispersed Iridium I written by David Keith Lyon and published by . This book was released on 1990 with total page 458 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Synthesis Characterization and Catalysis of Rhodium molybdenum Bimetallic Catalysts and Related Metal oxide Catalysts for Oxygenate Synthesis written by Mure Te and published by . This book was released on 1996 with total page 412 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Synthesis Characterization and Reactivity of Rhodium and Iridium iminophosphorane Complexes written by Pieter Imhof and published by . This book was released on 1990 with total page 153 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Synthesis and Characterization of Supported Rhenium Iridium and Platinum Catalysts written by Scott K. Purnell and published by . This book was released on 1994 with total page 600 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Design and Synthesis of Rhodium and Iridium Bis 2 Diolefin Catalysts written by Michaela-Christina Melcher and published by . This book was released on 2018 with total page 116 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Rhodium and Iridium Complexes Supported by Chelating Bis N heterocyclic Carbene Ligands written by Roxy Joanne Lowry and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: ABSTRACT: Eighty-five percent of all industrial chemical processes occur catalytically. The world's expanding appetite for mass production of exotic chemicals necessitates the design and application of enhanced catalysts. To optimize catalytic materials, the detailed relationships between catalyst architecture and reactivity must be determined. Although for many ligand families these relationships are well understood, novel catalysts require in depth empirical investigation to determine these connections. The design of a novel di-N-heterocyclic carbene family of ligands in reported herein. These C2 symmetric ligands are based on the rigid 9,10-dihydro-9,10-ethanoanthracene backbone and designed for utilization in chiral catalysis. Thorough investigation into the relationships between the ligand's structure and the architecture of the resulting rhodium and iridium catalysts directed the design of three generations of our novel ligand family. The first generation, trans-1,1'-[9,10-dihydro-9,10-ethanoanthracene-11,12- diyldimethanediyl]bis(benzylimidazole) bis(triflouromethansulfonate) [DEAM-BI](OTf)2 (2-1), is too flexible to enforce a rigid chiral pocket about a metal center under catalytic conditions. The constrained second generation ligands, trans-1,1'-(9,10-dihydro-9,10-ethanoanthracene.
