Download or read book Preparation and Characterisation of Supported Palladium Platinum and Ruthenium Catalysts for Cinnamaldehyde Hydrogenation written by Mohamed Lashdaf and published by . This book was released on 2004 with total page 70 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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.

Download or read book Synthesis Characterization and Preparation of Platinum ruthenium Catalysts written by Hong Yian Lin and published by . This book was released on 1998 with total page 66 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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.

Download or read book Supported Platinum and Iridium Catalysts for the Selective Hydrogenation of Cinnamaldehyde written by Louise Theodoulou and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Synthesis Characterization and Catalytic Testing of Palladium and Nickel Based Intermetallic Compounds for Acetylene Semi hydrogenation written by Anish Dasgupta and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Intermetallic compounds often offer opportunities for synthesis of site isolated catalysts having precise active site coordination and morphology. They are also resistant to segregation effects (compared to random alloys) because of the high heat of formation of their unique electronically stabilized crystal structures. Due to predictable, periodic and easily reproducible nature of the isolated active sites, suitably chosen intermetallic compounds can act as excellent model systems for studying catalytic structure function correlation in different small molecule chemistries. In the current dissertation I utilized H2-D2 exchange in addition to ethylene and acetylene hydrogenation as the probe reactions of choice. My ultimate target is to understand and quantify the effect of active site (transition metal) isolation during the semi-hydrogenation of acetylene in an ethylene rich stream, which is a key step in industrial polyethylene synthesisa multi-hundred-billion-dollar industry. I studied two different classes of catalysts for this chemistry: Pd-(M)-Zn (M=Cu, Ag, Au) -brass intermetallics and Ni-Ga intermetallics. I used micron scale bulk materials as model catalysts because they provide greater compositional control and allows for studying the intrinsic catalytic property of the intermetallic, free from support and ligand effects.A significant part of the text is dedicated to the synthesis, characterization and catalytic study of the bulk Pd-(M)-Zn ternary -brass phase materials because of its unique adaptability in terms of developing a family of closely related model catalysts having Pd-M-Pd active sites (M=Pd, Zn, Au, Cu and Ag) which can change the semi-hydrogenation activity and selectivity by two orders of magnitude even when only one atom is changed per 52 atom unit cell. As an extension of this project I also report several Pd-Ni-Zn and Pd-Pt-Zn ternary -brass phases and determine their atomic site occupancy factors.During the course of my research I realized there were no reported methods for synthesizing Pd-Zn and Ni-Zn -brass intermetallics as catalytically relevant supported nano-particles (NPs). I developed and optimized a hybrid generalized synthesis approach for SiO2 supported Pd-Zn, Ni-Zn and Cu-Zn -brass NPs. I also provide preliminary evidence that this approach can be easily extended to the synthesis of ternary NPs as well.In the case of Ni-Ga intermetallics, I tried to understand the role of Ga in controlling acetylene semi-hydrogenation. I observed a reversal in the ethylene selectivity trend with Ga content between 85 C and 160 C which is unexpected based on published DFT calculations. Previously, it has been suggested that Ga simply acts as a spacer for isolating Ni/Pd active sites much like Zn in the case of Ni-Zn catalysts (studied by Charles Spanjers from our research group). However, Ga has a higher affinity to hydrogen compared to Zn and I attempted to investigate if Ga may have a weak but non-negligible catalytic contribution towards hydrogenation which has typically not been previously considered in any detail in the case of acetylene semi-hydrogenation on metallic catalysts. Additionally, I provide understanding behind the high acetylene semi-hydrogenation selectivity of Ni5Zn21 catalyst which was originally reported by Spanjers et al. (J. Catal. 2014). This involved identifying the site occupation factor of Ni and Zn in the -brass lattice for materials having greater than 15.4 at% Ni. It is determined that (unlike Pd-Zn -brass) exactly single atom Ni1 active sites are exposed on the surface irrespective of the Ni concentration (even though Ni3 clusters are present in the bulk) which explains the suppression of over-hydrogenation and oligomerization on this catalyst, resulting in the high ethylene selectivity reported by Spanjers et al.

Download or read book Preparation and Characterisation of Carbon Supported Palladium Catalysts written by L. L. Mkayula and published by . This book was released on 1986 with total page 235 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Preparation and Characterisation of a Model Supported Ruthenium Catalyst written by N. Aas and published by . This book was released on 1990 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Horizons in Sustainable Industrial Chemistry and Catalysis written by Stefania Albonetti and published by Elsevier. This book was released on 2019-02-13 with total page 444 pages. Available in PDF, EPUB and Kindle. Book excerpt: Horizons in Sustainable Industrial Chemistry and Catalysis, Volume 178, presents a comprehensive picture of recent developments in terms of sustainable industrial processes and the catalytic needs and opportunities to develop these novel routes. Each chapter includes an introduction and state-of-the-art in the field, along with a series of specific aspects and examples. The book identifies new opportunities for research that will help us transition to low carbon and sustainable energy and chemical production. Users will find an integrated view of the new possibilities in this area that unleashes new possibilities in energy and chemistry. Combines an analysis of each scenario, the state-of-the art, and specific examples to help users better understand needs, opportunities, gaps and challenges Offers an integrated view of new catalytic technologies that are needed for future use Presents an interdisciplinary approach that combines broad expertise Brings together experts in the area of sustainable industrial chemistry

Download or read book The Synthesis of Nitrogen Doped Carbon Spheres as Supports for Palladium Catalysts in the Hydrogenation of Cinnamaldehyde written by Sibongile Mary-Anne Manikai and published by . This book was released on 2015 with total page 406 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Synthesis and Characterization of Novel Palladium and Platinum Phosphanylhydrazine Complexes and Their Potential Use as Catalysts written by Douglas J. Schaffer and published by . This book was released on 2009 with total page 182 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Palladium Reagents and Catalysts written by Jiro Tsuji and published by . This book was released on 1995 with total page 596 pages. Available in PDF, EPUB and Kindle. Book excerpt: Basic chemistry of organopalladium compounds; Classification of the reactions involving Pd(II) compounds and Pd(O) complexes.

Download or read book Characterisation and Activity of Polymer Supported Platinum and Gold in Catalytic Hydrogenation Reactions written by C. H. Azhari and published by . This book was released on 1985 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Effect of Alumina Grinding on the Properties of Alumina Supported Palladium Catalysts in Selective Hydrogenation of Acetylene written by and published by . This book was released on 2008 with total page 190 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this study, the effects of alumina grinding and mixed oxides (ZnO-Al2O3 and NiO-Al2O3) grinding with various Zn/Al and Ni/Al molar ratios (0.1 and 0.5) prepared by an attrition ball mill on catalytic performance of alumina supported Pd catalysts for selective hydrogenation of acetylene were investigated. It was found that catalytic performances of the Pd catalyst supported on Al2O3 milled for 12 h were superior compared to those of Pd-supported on the unmilled Al2O3. However, all the catalysts prepared from milled mixed oxides presented lower acetylene conversion and ethylene selectivity than that of the catalyst prepared from alumina milled for 12 h. From X-ray diffraction, it was suggested that varying milling time directly affected the crystallite size, surface area and acidity of alumina supports. As revealed by CO chemisorption, milling of Al2O3 supports could increase metal active sites of Pd/Al2O3 catalysts without change in the interaction between Pd and the alumina support so that the catalysts exhibited higher acetylene activity and ethylene selectivity. Moreover, increasing of acidity affected coke formation on the catalysts.

Download or read book Characterization of Supported Gold Platinum gold and Platinum Catalysts for Hydrogenation Reactions written by Eveline Bus and published by . This book was released on 2007 with total page 197 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Supported Bimetallic Catalysts Derived from Platinum gold Phosphine Stabilized Cluster Compounds Their Preparation Characterization and Catalytic Activity written by Irina Vladimirovna Gubkina Graf and published by . This book was released on 1996 with total page 492 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Preparation Characterisation and Catalytic Behaviour of Ruthenium Based Catalyst in Carbon Monoxide Hydrogenation written by Adel M. Al-Hussaini and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: