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Book Selective Hydrogenation of an A b unsaturated Aldehyde Using Palladium Catalysts

Download or read book Selective Hydrogenation of an A b unsaturated Aldehyde Using Palladium Catalysts written by Matteo Navarria and published by . This book was released on 2002 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Selective Hydrogenation of alpha beta alpha Beta unsaturated Aldehydes Towards Clean Synthesis Over Noble Metal Catalysts in Mass Transfer Efficient Three Phase Reactors

Download or read book Selective Hydrogenation of alpha beta alpha Beta unsaturated Aldehydes Towards Clean Synthesis Over Noble Metal Catalysts in Mass Transfer Efficient Three Phase Reactors written by Laiqi Zhang and published by . This book was released on 1998 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The hydrodynamics and mass transfer characteristics of a concurrent downflow contactor (CDC) are studied in this work in order to investigate the viability of this bubble column as a catalytic reactor for the hydrogenation of?,?-unsaturated aldehydes. Oxygen/water was used as the system throughout. In order to obtain reproducible results, a very effective gas-liquid separation method was conceived and developed after much trial and error work. Shutdown and deadleg gas holdup measuring methods were compared and it was found that the shutdown method is more reliable than the deadleg method. The hydrogenation of cinnamaldehyde using both in-house-prepared and commercial palladium, platinum and ruthenium catalysts was carried out in stirred tank reactors and cocurrent downflow reactors in order to study the kinetics and mass transfer characteristics and the selectivity towards the corresponding desired product, hydrocinnamaldehyde or cinnamyl alcohol. When palladium catalysts were used the desired product was hydrocinnamaldehyde. The effects of homogenous reactions, type of solvent, catalyst loading, temperature, pressure, reactant concentration and the effects of promoter or poison on the selectivity towards hydrocinnamaldehyde were investigated systematically. Aldehyde acetals were produced in polar solvents, but not in non-polar solvents. Two methods can be used to obtain hydrocinnamaldehyde selectivity without reduction of the carbonyl double bond: (1) by using non-polar solvents such as toluene; (2) by incorporating poisons or promoters into the reactant solution or onto the surface of the catalysts. 97% selectivity to hydrocinnamaldehyde was achieved. The effects of the solvent, temperature, pressure, catalyst loading, promoters, and reactants concentration on the kinetics were studied and the following reaction kinetics are proposed for the hydrogenation of cinnamaldehyde over non-modified palladium/charcoal catalysts in propan-2-ol and in toluene: Ra = kC\(_{Cat}\)C\(_{H2}\)C\(0_{CAL}\) The apparent activation energy varies with themperature range in propan-2-ol and is 65\(\pm\)5 kJ.mol\({-1}\) in toluene.

Book Selective Hydrogenation of alpha beta unsaturated Aldehydes Towards Clean Synthesis Over Noble Metal Catalysts in Mass Transfer Efficient Three Phase Reactors

Download or read book Selective Hydrogenation of alpha beta unsaturated Aldehydes Towards Clean Synthesis Over Noble Metal Catalysts in Mass Transfer Efficient Three Phase Reactors written by Laiqi Zhang and published by . This book was released on 1998 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The hydrodynamics and mass transfer characteristics of a concurrent downflow contactor (CDC) are studied in this work in order to investigate the viability of this bubble column as a catalytic reactor for the hydrogenation of ?,?-unsaturated aldehydes. Oxygen/water was used as the system throughout. In order to obtain reproducible results, a very effective gas-liquid separation method was conceived and developed after much trial and error work. Shutdown and deadleg gas holdup measuring methods were compared and it was found that the shutdown method is more reliable than the deadleg method. The hydrogenation of cinnamaldehyde using both in-house-prepared and commercial palladium, platinum and ruthenium catalysts was carried out in stirred tank reactors and cocurrent downflow reactors in order to study the kinetics and mass transfer characteristics and the selectivity towards the corresponding desired product, hydrocinnamaldehyde or cinnamyl alcohol. When palladium catalysts were used the desired product was hydrocinnamaldehyde. The effects of homogenous reactions, type of solvent, catalyst loading, temperature, pressure, reactant concentration and the effects of promoter or poison on the selectivity towards hydrocinnamaldehyde were investigated systematically. Aldehyde acetals were produced in polar solvents, but not in non-polar solvents. Two methods can be used to obtain hydrocinnamaldehyde selectivity without reduction of the carbonyl double bond: (1) by using non-polar solvents such as toluene; (2) by incorporating poisons or promoters into the reactant solution or onto the surface of the catalysts. 97% selectivity to hydrocinnamaldehyde was achieved. The effects of the solvent, temperature, pressure, catalyst loading, promoters, and reactants concentration on the kinetics were studied and the following reaction kinetics are proposed for the hydrogenation of cinnamaldehyde over non-modified palladium/charcoal catalysts in propan-2-ol and in toluene: Ra = kC\(-{Cat}\)C\(-{H2}\)C\( 0-{CAL}\) The apparent activation energy varies with themperature range in propan-2-ol and is 65\(\pm\)5 kJ.mol\( {-1}\) in toluene.

Book Selective Hydrogenation of alpha beta unsaturated Aldehydes Over Metal Catalysts

Download or read book Selective Hydrogenation of alpha beta unsaturated Aldehydes Over Metal Catalysts written by Thomas Balder Ludwig Wolfgang Marinelli and published by . This book was released on 1993 with total page 129 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Palladium as a Catalyst for Selective Hydrogenation

Download or read book Palladium as a Catalyst for Selective Hydrogenation written by Takht Ravanchi Maryam and published by LAP Lambert Academic Publishing. This book was released on 2015-10-15 with total page 188 pages. Available in PDF, EPUB and Kindle. Book excerpt: The selective hydrogenation of multi-unsaturated hydrocarbons, especially in pyrolysis products, to corresponding mono-olefins is a widely exploited way for large-scale production of polymer-grade olefins and also upgrading of gasoline blending stocks. Thermodynamic and/or kinetic parameters could be responsible for directing the reaction network to a special product. This book deals with application of palladium-based catalysts in selective hydrogenation of alkynes and diens. It covers both fundamental and applied aspects of selective hydrogenation with special emphasis on the selectivity problem. The book is organized in rational way beginning with the electronic structure of palladium, followed by its catalytic properties, interaction with supports and transport limitations and commercial applications.

Book Selective Hydrogenation of alpha beta Unsaturated Aldehydes Over Ir Catalysts

Download or read book Selective Hydrogenation of alpha beta Unsaturated Aldehydes Over Ir Catalysts written by J. Gomez-Lopez and published by . This book was released on 2004 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Selective Hydrogenation of Alpha Beta unsaturated Aldehydes Towards Clean Synthesis Over Noble Metal Catalysts in Mass Transfer Efficient Three Phase Reactors

Download or read book Selective Hydrogenation of Alpha Beta unsaturated Aldehydes Towards Clean Synthesis Over Noble Metal Catalysts in Mass Transfer Efficient Three Phase Reactors written by Lai Qi Zhang and published by . This book was released on 1997 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Selective Hydrogenation of alpha beta Unsaturated Aldehydes Over Ir Catalysts

Download or read book Selective Hydrogenation of alpha beta Unsaturated Aldehydes Over Ir Catalysts written by J. Gomez-Lopez and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Palladium catalyzed Aerobic alpha Beta dehydrogenation of Carbonyl Compounds

Download or read book Palladium catalyzed Aerobic alpha Beta dehydrogenation of Carbonyl Compounds written by and published by . This book was released on 2012 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: [Alpha, beta]-Unsaturated carbonyl compounds are versatile intermediates in the synthesis of pharmaceuticals and biologically active molecules. The research described herein focuses on the development and mechanistic study of Palladium catalysts for direct aerobic dehydrogenation of ketones and aldehydes to afford the corresponding [alpha, beta]-unsaturated carbonyl compounds. The discovery and application of a novel aerobic dehydrogenation catalyst, Pd(DMSO)2(TFA)2, led to selective dehydrogenation of various cyclohexanone derivatives to afford cyclohexenone products that are of synthetic interest. A complementary Pd(TFA)2/4,5-diazafluorenone catalyst was developed for [alpha, beta]-dehydrogenation of acyclic ketones and aldehydes, with useful applications in preparing unsaturated heterocyclic carbonyl compounds. Characterization of the solution-phase structure of the Pd(DMSO)2(TFA)2 catalyst by NMR spectroscopy suggested that the bis-DMSO ligation to PdII was favorable under the catalytic conditions. Further kinetic studies of Pd(DMSO)2(TFA)2-catalyzed dehydrogenation of cyclohexenone revealed that the DMSO ligands kinetically control the selectivity of dehydrogenation. A fundamental study of the influence of O2 on the acetoxylation of ([pi]-allyl)Pd complexes is also detailed. The fact that O2 is capable of promoting reductive C-O bond formation of ([pi]-allyl)Pd complexes has important implications in understanding the interaction between Pd and O2 and provides a basis for development of Pd-catalyzed aerobic allylic acetoxylation of alkenes.

Book Carbon Supported Palladium Catalysts in Selective Hydrogenation Reactions

Download or read book Carbon Supported Palladium Catalysts in Selective Hydrogenation Reactions written by Fiona-Mairéad McKenna and published by . This book was released on 2006 with total page 122 pages. Available in PDF, EPUB and Kindle. Book excerpt: