Pd catalysts supported on dual-pore monolithic silica beads for chemoselective hydrogenation under batch and flow reaction conditions

2020 ◽  
Vol 10 (18) ◽  
pp. 6359-6367
Author(s):  
Tsuyoshi Yamada ◽  
Aya Ogawa ◽  
Hayato Masuda ◽  
Wataru Teranishi ◽  
Akiko Fujii ◽  
...  
Keyword(s):  
Palladium Catalysts ◽  
Reaction Conditions ◽  
Pd Catalysts ◽  
Monolithic Silica ◽  
Chemoselective Hydrogenation ◽  
Different Types ◽  
Silica Beads ◽  
Flow Reaction

Two different types of palladium catalysts supported on dual-pore monolithic silica beads [5% Pd/SM and 0.25% Pd/SM(sc)] for chemoselective hydrogenation were developed.

A Single Turnover (STO) Characterization of Supported Palladium Catalysts

1987 ◽  
Vol 111 ◽  
Author(s):  
Robert L. Augustine ◽  
David R. Baum
Keyword(s):  
Palladium Catalysts ◽  
Active Sites ◽  
Pt Catalyst ◽  
Catalyst Characterization ◽  
Pt Catalysts ◽  
Ambient Conditions ◽  
Reaction Conditions ◽  
Pd Catalysts ◽  
Supported Pt Catalysts

AbstractWhile the STO catalyst characterization procedure has been applied to a variety of supported Pt catalysts, application of this technique to the characterization of supported Pd catalysts showed that there were several significant differences between the Pt and the Pd catalysts. Under STO reaction conditions each surface site on a Pt catalyst reacts only once so there is a 1:1 relationship between the product composition and the densities of the various types of active sites present. With Pd catalysts under these same conditions, alkene isomerization takes place so readily that the amount of isomerized product formed depends on the contact time of the reactant pulse with the catalyst so there is no direct relationship between the amount of isomerization and the number of isomerization sites present. On Pt there are some direct saturation sites present on which H2 is rather weakly held. Such sites are not present on Pd catalysts. The reactive surface of supported Pt catalysts remains constant on long exposure to air. With Pd catalysts exposure to air results in a decrease in saturation site densities which can be reversed by re-reduction of the surface with H2 under ambient conditions but not completely under what can be termed “reaction conditions” where the extent of surface re-reduction decreases with catalyst age.

scholarly journals Heterogeneous Pd catalysts supported on silica matrices

RSC Advances ◽  
2014 ◽  
Vol 4 (110) ◽  
pp. 65137-65162 ◽  
Author(s):  
Maksym Opanasenko ◽  
Petr Štěpnička ◽  
Jiří Čejka
Keyword(s):  
Palladium Catalysts ◽  
Organic Transformations ◽  
Pd Catalysts ◽  
Different Types ◽  
Silica Matrices

Features, advantages and limitations associated with palladium catalysts deposited over various siliceous supports in different types of practically useful organic transformations are reviewed.

Model reactions for the study of hydrogenation and acidic activity of palladium catalysts

1987 ◽  
Vol 52 (8) ◽  
pp. 2019-2027 ◽  
Author(s):  
Libor Červený ◽  
Nguyen Thi Du ◽  
Ivo Paseka
Keyword(s):  
Palladium Catalysts ◽  
Styrene Oxide ◽  
Side Reactions ◽  
Pd Catalysts ◽  
Variable Parameters ◽  
Acid Properties ◽  
Liquid Phase Hydrogenation ◽  
Acid Catalysed Reactions ◽  
Different Content ◽  
Model Reactions

Palladium catalysts have been used to study the hydrogenation of 1-phenyl-2-butene-1-ol which is accompanied by several side reactions considered to be acid-catalysed. Another model reaction studied was dehydration and subsequent hydrogenation or hydrogenolysis of 1-phenyl-1,3-propanediol to 3-phenyl-1-propanol, accompanied by formation of propylbenzene. The dehydration and propylbenzene formation can be again classified as acid-catalysed reactions. Another one is methanolysis of styrene oxide taking place under conditions of liquid phase hydrogenation due to the acid properties of Pd-H systems. Hydrogenation activity of Pd catalysts was tested by hydrogenation of cyclohexene. Sixteen Pd catalysts on different supports and with different content of active component were used, their activity and selectivity was determined and the effect of variable parameters in the synthesis of these catalysts on the activity and selectivity is discussed.

scholarly journals Development of palladium catalysts modified by ruthenium and molybdenum as anode in direct ethanol fuel cell

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Yonis Fornazier Filho ◽  
Ana Caroliny Carvalho da Cruz ◽  
Rolando Pedicini ◽  
José Ricardo Cezar Salgado ◽  
Priscilla Paiva Luz ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Palladium Catalysts ◽  
Carbon Support ◽  
X Ray Diffraction ◽  
Direct Ethanol Fuel Cell ◽  
Pd Catalysts ◽  
Bifunctional Mechanism ◽  
Catalytic Activities ◽  
Intrinsic Mechanism ◽  
Ternary Catalysts

AbstractPhysical and electrochemical properties of Pd catalysts combined with Ru and Mo on carbon support were investigated. To this end, Pd, Pd1.3Ru1.0, Pd3.2Ru1.3Mo1.0 and Pd1.5Ru0.8Mo1.0 were synthesized on Carbon Vulcan XC72 support by the method of thermal decomposition of polymeric precursors and then physically and electrochemically characterized. The highest reaction yields are obtained for Pd3.2Ru1.3Mo1.0/C and Pd1.5Ru0.8Mo1.0/C and, as demonstrated by thermal analysis, they also show the smallest metal/carbon ratio compared the other catalysts. XRD (X-ray Diffraction) and Raman analyses show the presence of PdO and RuO2 for the Pd/C and the Pd1.3Ru1.0/C catalysts, respectively, a fact not observed for the Pd3.2Ru1.3 Mo1.0 /C and the Pd1.5Ru0.8Mo1.0/C catalysts. The catalytic activities were tested for the ethanol oxidation in alkaline medium. Cyclic voltammetry (CV) shows Pd1.3Ru1.0/C exhibiting the highest peak of current density, followed by Pd3.2Ru1.3Mo1.0/C, Pd1.5Ru0.8Mo1.0/C and Pd/C. From, chronoamperometry (CA), it is possible to observe the lowest rate of poisoning for the Pd1.3Ru1.0/C, followed by Pd3.2Ru1.3Mo1.0/C, Pd1.5Ru0.8Mo1.0/C and Pd/C. These results suggested that catalytic activity of the binary and the ternary catalysts are improved in comparison with Pd/C. The presence of RuO2 activated the bifunctional mechanism and improved the catalytic activity in the Pd1.3Ru1.0/C catalyst. The addition of Mo in the catalysts enhanced the catalytic activity by the intrinsic mechanism, suggesting a synergistic effect between metals. In summary, we suggest that it is possible to synthesize ternary PdRuMo catalysts supported on Carbon Vulcan XC72, resulting in materials with lower poisoning rates and lower costs than Pd/C. Graphic abstract

Ring-opening Addition Reactions of 1-tert-Butoxycarbonyl-3,4- epoxypiperidine with Amine Nucleophiles

2010 ◽  
Vol 65 (2) ◽  
pp. 197-202 ◽  
Author(s):  
Boja Poojary ◽  
Lim Hee-Jong
Keyword(s):  
Ring Opening ◽  
Addition Reactions ◽  
Reaction Conditions ◽  
Different Types

Ring-opening addition reactions of 1-tert-butoxycarbonyl-3,4-epoxypiperidine leading to the formation of the corresponding regioisomeric trans-β -aminoalcohols were carried out with three different types of amine nucleophiles under different reaction conditions with a view to study the reactivity and regioselectivity.

The Preparation of Iron Carbonyl Complexes of Fluorocarbon-Bridged Ligands

1972 ◽  
Vol 50 (14) ◽  
pp. 2182-2194 ◽  
Author(s):  
L. S. Chia ◽  
W. R. Cullen ◽  
D. A. Harbourne
Keyword(s):  
Iron Carbonyl ◽  
Carbonyl Complexes ◽  
Reaction Conditions ◽  
Iron Carbonyls ◽  
Mixed Ligands ◽  
Different Types

The reactions of the ligands [Formula: see text] L′ = (CH3)2As, (C6H5)2P; n = 4, 6, 8; but not all combinations) with iron carbonyls are described in detail. The nature of the products is discussed as a function of the reaction conditions and the ligands. The mixed ligands yield eight different types of complexes which have been characterized. Two of these types (L—L′)2Fe2(CO)4. and (L—L′)2Fe(CO)3 were previously unknown.

scholarly journals Chemoselective hydrogenation of cinnamaldehyde at atmospheric pressure over combustion synthesized Pd catalysts

2017 ◽  
Vol 122 (1) ◽  
pp. 135-153 ◽  
Author(s):  
Dipak Das ◽  
Kamalesh Pal ◽  
Jordi Llorca ◽  
Montserrat Dominguez ◽  
Sara Colussi ◽  
...  
Keyword(s):  
Atmospheric Pressure ◽  
Pd Catalysts ◽  
Chemoselective Hydrogenation

scholarly journals Altervalent cation-doped MCM-41 supported palladium catalysts and their catalytic properties

2011 ◽  
Vol 76 (6) ◽  
pp. 923-932 ◽  
Author(s):  
Haihui Jiang ◽  
Ligang Gai ◽  
Yan Tian
Keyword(s):  
Electron Microscopy ◽  
Palladium Catalysts ◽  
Xrd Analysis ◽  
Molar Ratio ◽  
Pd Catalysts ◽  
Transmission Electron ◽  
Supported Pd Catalysts ◽  
Supported Palladium ◽  
Mcm 41 ◽  
Supported Pd

Metal cation-doped MCM-41 (M-MCM-41, M=Al, Ce, Co, V, or Zr) supported Pd catalysts (Pd/M-MCM-41) were prepared by a solution-based reduction method. The catalysts were characterized by Xray diffraction (XRD) analysis, infrared spectroscopy (IR), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and further evaluated by selective hydrogenation of parachloronitrobenzene (p-CNB) in anhydrous ethanol. The metal cationcontaining Pd catalysts can efficiently enhance the selectivity for parachloroaniline (p-CAN). The highest selectivity of 96.5 % in the molar distribution for p-CNB to p-CAN was acquired over Pd (1.8 wt. %)/VMCM- 41 (Si/V=30, molar ratio) catalyst, and the corresponding turnover frequency (TOF) was 1.24?10-2 mol p-CNB mol-1 Pd s-1. Water molecules adsorbed by the support have important effects on both the catalytic activity of the sample and the selectivity for p-CAN. A water molecule-mediated catalytic hydrogenation is discussed.

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