EBookClubs

Read Books & Download eBooks Full Online

EBookClubs

Read Books & Download eBooks Full Online

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 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 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 Hyddrogenation of alpha beta unsaturated Aldehydes Over Metal Catalysts

Download or read book Selective Hyddrogenation 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 Homogeneous Hydrogenation with Non Precious Catalysts

Download or read book Homogeneous Hydrogenation with Non Precious Catalysts written by Johannes F. Teichert and published by John Wiley & Sons. This book was released on 2019-10-22 with total page 397 pages. Available in PDF, EPUB and Kindle. Book excerpt: A guide and comprehensive review of the most recent advances in homogeneous hydrogenation with non-precious catalysts In recent years a great deal of research has been applied to homogeneous hydrogenation with non-precious catalysis. Homogeneous Hydrogenation with Non-Precious Catalysts offers a review of the latest developments and advances in the field. In addition, the book explores the transition metal catalysis and the concept of frustrated-lewis-pair (FLP) and enzymatic processes. The editor?a noted expert on the topic?discusses the various catalysts and puts the focus on the synthetic vantage point, highlighting the functional group transformation enabled by the respective catalyst. Homogeneous Hydrogenation with Non-Precious Catalysts also presents the industrial view of the topic and includes an overview of the various catalysts by functional group transformations. This important book: -Offers a comprehensive presentation of the newest development in this emerging field -Highlights the transition metal catalysis, the frustrated-lewis-pair (FLP) concept, and enzymatic processes -Provides an industrial perspective of the topic -Includes an overview of the various catalysis by functional group transformations Written for organic chemists, researchers in synthetic chemistry, and industry professionals, Homogeneous Hydrogenation with Non-Precious Catalysts offers a comprehensive and accessible guide to the most recent advances in the field. [/COPY_WEB_CATALOG]

Book Heterogeneous Enantioselective Hydrogenation

Download or read book Heterogeneous Enantioselective Hydrogenation written by Evgenii Klabunovskii and published by Springer Science & Business Media. This book was released on 2007-05-22 with total page 314 pages. Available in PDF, EPUB and Kindle. Book excerpt: Heterogeneous Enantioselective Hydrogenation: Theory and Practice reviews the development of enantioselective hydrogenation reaction catalysts. It looks at the first relatively ineffective catalysts right through to modern highly effective enantioselective catalytic systems, comparable in their efficiency to chiral metal complexes and enzymatic systems. The book begins with a summary of the first work on heterogeneous metal catalysts, which showed only the principal possibilities of enantioselective reactions. It then elaborates on metal catalysts which have enantioselectivities close to 100%. Finally, the practical utilization of chiral catalytic systems in processes of hydrogenation is described. The alpha- and beta-hydroxy carboxylic acid esters produced are precursors for manufacturing many synthones used for medicines as well as for monomers used for biodegradable polyesters, both of which have important practical applications. The volume summarizes more than 800 scientific papers in the field of enantioselective catalytic hydrogenation reactions, mainly those using heterogeneous metal catalysts. It provides detailed explanations of special techniques for the preparation of effective dissymmetric catalysts which provide highly efficient catalytic systems.

Book Selective Hydrogenation and Transfer Hydrogenation Reactions

Download or read book Selective Hydrogenation and Transfer Hydrogenation Reactions written by Ronald Alvaro Farrar Tobar and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation describes the research on catalysts active for the selective transfer hydrogenation (TH) of [alpha],[beta]-unsaturated carbonyl compounds using EtOH as H2 source as alternative to commonly used iPrOH. Furthermore, a base-free iron-based protocol is designed and optimized for the novel TH of ester compounds using EtOH as H2 source. In addition, the chemical activity of new single rhodium atoms on Al2O3 is explored. Using limonene as a model compound, only the terminal olefin was hydrogenated and the potential selective character of the catalyst is highlighted.eng

Book Hydrogenation of the Alpha Beta Unsaturated Aldehydes Acrolein Crotonaldehyde and Prenal Over Pt Single Crystals

Download or read book Hydrogenation of the Alpha Beta Unsaturated Aldehydes Acrolein Crotonaldehyde and Prenal Over Pt Single Crystals written by and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Sum-frequency generation vibrational spectroscopy (SFG-VS) and kinetic measurements using gas chromatography have been used to study the surface reaction intermediates during the hydrogenation of three?,?-unsaturated aldehydes, acrolein, crotonaldehyde, and prenal, over Pt(111) at Torr pressures (1 Torr aldehyde, 100 Torr hydrogen) in the temperature range of 295K to 415K. SFG-VS data showed that acrolein has mixed adsorption species of?2-di-?(CC)-trans,?2-di-?(CC)-cis as well as highly coordinated?3 or?4 species. Crotonaldehyde adsorbed to Pt(111) as?2 surface intermediates. SFG-VS during prenal hydrogenation also suggested the presence of the?2 adsorption species, and became more highly coordinated as the temperature was raised to 415K, in agreement with its enhanced C=O hydrogenation. The effect of catalyst surface structure was clarified by carrying out the hydrogenation of crotonaldehyde over both Pt(111) and Pt(100) single crystals while acquiring the SFG-VS spectra in situ. Both the kinetics and SFG-VS showed little structure sensitivity. Pt(100) generated more decarbonylation 'cracking' product while Pt(111) had a higher selectivity for the formation of the desired unsaturated alcohol, crotylalcohol.

Book Applications of Hydrogenation and Dehydrogenation on Noble Metal Catalysts

Download or read book Applications of Hydrogenation and Dehydrogenation on Noble Metal Catalysts written by Bo Wang and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Hydrogenation and dehydrogenation on Pd- and Pt- catalysts are encountered in many industrial hydrocarbon processes. The present work considers the development of catalysts and their kinetic modeling along a general and rigorous approach. The first part deals with the kinetics of selective hydrogenation, more particularly of the C3 cut of a thermal cracking unit for olefins production. The kinetics of the gas phase selective hydrogenation of methyl-acetylene (MA) and propadiene (PD) over a Pd/y-alumina catalyst were investigated in a fixed bed tubular reactor at temperatures 60 - 80 oC and a pressure of 20 bara. Hougen-Watson type kinetic equations were derived. The formation of higher oligomers slowly deactivated the catalyst. The effect of the deactivating agent on the rates of the main reactions as well as on the deactivating agent formation itself was expressed in terms of a deactivation function multiplying the corresponding rates at zero deactivation. Then, the kinetic model was plugged into the reactor model to simulate an industrial adiabatic reactor. In the second part the production of hydrogen from hydrocarbons was investigated. In both cyclohexane and decalin dehydrogenations, conversions higher than 98% could be obtained over Pd/y-alumina catalyst at temperature of 320 and 340 oC, respectively, with no apparent deactivation for 30 h and with co-feed of H2 in the feed. Except for H2 and trace amounts of side cracking products, less than 0.01%, benzene was the only dehydrogenated product in cyclohexane dehydrogenation. In the case of decalin dehydrogenation, partially dehydrogenated product, tetralin, was also formed with selectivity lower than 5%, depending on operating conditions. A rigorous Hougen-Watson type kinetic model was derived, which accounted for both the dehydrogenation of cis- and trans- decalin in the feed and also the isomerization of the two isomers. Jet A is the logic fuel in the battlefields. The dehydrogenation of Jet A can produce H2 for military fuel cell application. Although the H2 production is lower than that of steam/autothermal reforming, it eliminates the needs of high temperature and product separation operation.