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.

Effect of internal diffusion on kinetics of liquid phase hydrogenation and disproportionation of the cyclohexene on palladium catalysts

1989 ◽  
Vol 54 (11) ◽  
pp. 3003-3010 ◽  
Author(s):  
Jiří Hanika ◽  
Vladimíra Ehlová
Keyword(s):  
Liquid Phase ◽  
Palladium Catalysts ◽  
Internal Diffusion ◽  
Side Reactions ◽  
Commercial Catalyst ◽  
Liquid Phase Hydrogenation ◽  
Effectiveness Factors ◽  
Supported Palladium ◽  
Kinetics Of ◽  
Diffusion Of Hydrogen

Kinetics of the side reactions represented by the system involving hydrogenation and disproportionation of cyclohexene on a commercial catalyst CHEROX 41-00 (3%Pd/C) and on a supported palladium catalyst prepared by impregnation of aluminia with aqueous palladium dichloride (2.15% Pd/γ-Al2O3) have been investigated. As follows from the effectiveness factors of internal diffusion for individual reactions, in the region of internal diffusion, cyclohexene hydrogenation is preferred compared to disproportionation. This finding can be related to the fact that while the rate of disproportionation is controlled by cyclohexene diffusion, the rate of hydrogenation is controlled by diffusion of hydrogen.

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

Pd/SiO2–AlPO4 systems. Influence of the preparation variables on their catalytic activity

1985 ◽  
Vol 63 (12) ◽  
pp. 3471-3477 ◽  
Author(s):  
A. Alba ◽  
M. A. Aramendia ◽  
V. Borau ◽  
C. Jimenez ◽  
J. M. Marinas
Keyword(s):  
Catalytic Activity ◽  
Liquid Phase ◽  
Reaction Temperature ◽  
Hydrogen Pressure ◽  
Pd Catalysts ◽  
Metal Precursor ◽  
Preparation Conditions ◽  
Liquid Phase Hydrogenation ◽  
Initial Hydrogen Pressure ◽  
Catalyst Reduction

A study on the liquid phase hydrogenation of cyclohexene over a series of Pd catalysts supported on various SiO2–AlPO4 systems (using a concentration of 2.47 M, with methanol as solvent, the initial hydrogen pressure is 5 bar and reaction temperature 300 K) is reported in this paper. The reaction has been studied as a standard in order to determine the most suitable preparation conditions for these catalystsWe have also studied the influence of other factors such as the kind of support, the nature of the metal precursor, the previous calcination of the precursor, the addition of alkaline hydroxides, and the catalyst reduction with various agents, on the catalytic activity of different Pd-supported systems

Particle size effect in liquid-phase hydrogenation of phenylacetylene over Pd catalysts: Experimental data and theoretical analysis

2019 ◽  
Vol 358 ◽  
pp. 520-530 ◽  
Author(s):  
Pavel V. Markov ◽  
Igor S. Mashkovsky ◽  
Galina O. Bragina ◽  
Johan Wärnå ◽  
Evgenii Yu. Gerasimov ◽  
...  
Keyword(s):  
Experimental Data ◽  
Particle Size ◽  
Liquid Phase ◽  
Theoretical Analysis ◽  
Size Effect ◽  
Particle Size Effect ◽  
Pd Catalysts ◽  
Liquid Phase Hydrogenation

Role of polyaniline morphology in Pd particles dispersion. Hydrogenation of alkynes in the presence of Pd-polyaniline catalysts

2013 ◽  
Vol 67 (8) ◽  
Author(s):  
Robert Kosydar ◽  
Monika Goral ◽  
Alicja Drelinkiewicz ◽  
Jaroslav Stejskal
Keyword(s):  
Palladium Catalysts ◽  
Active Sites ◽  
Pd Nanoparticles ◽  
Liquid Phase Hydrogenation ◽  
Close Proximity ◽  
Physicochemical Features ◽  
Molecular Masses ◽  
Palladium Particles ◽  
Pani Sample

AbstractTwo polyaniline (PANI) samples of various molecular masses were used for the preparation of palladium catalysts (with 2 mass % of Pd). The physicochemical features of starting polyanilines were found to substantially affect the size and extent of palladium nanoparticles aggregation. Strongly aggregated large palladium particles appeared in the PANI sample of more compact morphology (PANI-H), higher crystallinity and lower specific surface area. Pd nanoparticles of a definitively smaller size were formed in the more amorphous PANI sample of looser morphology (PANI-L) and the extent of particles aggregation was markedly lower. The catalytic properties of Pd/PANI samples were studied in a liquid phase hydrogenation of unsaturated triple bond (C≡C) in alkynes reactants, phenylacetylene, and cyclohexylacetylene. The 2 mass % Pd/PANI-L catalyst prepared using polymer of less compact texture exhibited much higher activity in both reactions. In the presence of the 2 mass % Pd/PANI-L catalyst, alkene products were formed with a high selectivity (approximately 90 %) attained at the almost complete conversion of alkynes. This highly selective hydrogenation of the C≡C to the C=C bond was related to the presence of an electroactive polymer, PANI, in close proximity with Pd active sites. Polyaniline could have a role in a steric effect as well as in a modification of adsorptive properties of Pd centres.

Deactivation of silica supported Pd catalysts during liquid-phase hydrogenation

2005 ◽  
Vol 86 (1) ◽  
pp. 141-147 ◽  
Author(s):  
Joongjai Panpranot ◽  
Kanda Pattamakomsan ◽  
Piyasan Praserthdam
Keyword(s):  
Liquid Phase ◽  
Pd Catalysts ◽  
Liquid Phase Hydrogenation ◽  
Supported Pd Catalysts ◽  
Supported Pd

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.

Comparative deactivation study of nickel and palladium catalysts in liquid phase hydrogenation

1992 ◽  
Vol 89 ◽  
pp. 2029-2044
Author(s):  
P Alphonse ◽  
F Moyen ◽  
D Galletti ◽  
P Mauret
Keyword(s):  
Liquid Phase ◽  
Palladium Catalysts ◽  
Liquid Phase Hydrogenation
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