Hydrogenation and Hydrogenolysis of Acetophenone

2003 ◽  
Vol 68 (10) ◽  
pp. 1969-1984 ◽  
Author(s):  
Martina Bejblová ◽  
Petr Zámostný ◽  
Libor Červený ◽  
Jiří Čejka
Keyword(s):  
Reaction Mechanism ◽  
Liquid Phase ◽  
Kinetic Model ◽  
Active Carbon ◽  
Palladium Catalysts ◽  
Reaction Rates ◽  
Zeolite Support ◽  
Dehydration Mechanism ◽  
Supported Palladium ◽  
Very High

Catalytic hydrogenation and hydrogenolysis of acetophenone was investigated on supported palladium catalysts in liquid phase at temperatures 30-130 °C and pressures 1-10 MPa. A number of supports like active carbon, alumina and zeolites Beta and ZSM-5 were employed. The effects of solvent and support on the reaction mechanism of acetophenone transformation were studied. Catalysts with acid zeolite support showed a very high activity in transformation of acetophenone to ethylbenzene. Based on a kinetic model, the reaction rates of acetophenone transformation to ethylbenzene on Pd/C and Pd/Al2O3 catalysts were discussed. The kinetic model confirmed that the transformation of acetophenone to ethylbenzene proceeds primarily via a hydrogenation-dehydration mechanism and the effect of the direct hydrogenolysis of the C=O bond of acetophenone is insignificant.

scholarly journals HYDROGEN PRESSURE, SOLVENT AND CATALYST NATURE INFLUENCE ON THE 2-CHLORO-4-NITROANILINE HYDROGENATION REGULARITIES

2018 ◽  
Vol 61 (9-10) ◽  
pp. 30-35
Author(s):  
D.M. Klimushin ◽  
A.I. Krasnov ◽  
D.V. Filippov ◽  
N.Yu. Sharonov
Keyword(s):  
Liquid Phase ◽  
Ethyl Acetate ◽  
Palladium Catalysts ◽  
Metal Content ◽  
Hydrogen Pressure ◽  
Supported Catalysts ◽  
Platinum Catalysts ◽  
Target Product ◽  
Active Metal ◽  
Supported Palladium

The 2-chloro-4-nitroaniline liquid-phase hydrogenation kinetics on supported palladium and platinum catalysts differing in the nature of the carrier and the active metal content was studied for the first time. The experiment was carried out at elevated hydrogen pressures in the range of 9 - 12 atm and 303 K in solvents 2-propanol-water and ethyl acetate in the reactor such as Vishnevsky autoclave. The main kinetic parameters of the reaction have been determined, and the influence of various parameters on the regularities of the process has been established. It is shown that an increase in the active metal content in the catalyst leads to an increase in the rate of the hydrogenation reaction of 2-chloro-4-nitroaniline. When using platinum supported catalysts, the rate of hydrogenation of 2-chloro-4-nitroaniline is significantly higher than when using supported palladium catalysts. The replacement of the liquid phase of the catalyst system with 2-propanol by ethyl acetate adversely affects the reaction rate. The influence of the catalytic system nature and composition on the target product dehalogenation degree was determined. It was found that when carrying out the reaction at elevated hydrogen pressures, it is preferable to use low-percentage platinum catalysts, rather than palladium catalysts, since the former provide less dehalogenation of the target product. For citation: Klimushin D.M., Krasnov A.I., Filippov D.V., Sharonov N.Yu. Hydrogen pressure, solvent and catalyst nature influence on 2-chloro-4-nitroaniline hydrogenation regularities. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2018. V. 61. N 9-10. P. 30-35  

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 Liquid-phase Hydrogenation of Phenol to Cyclohexanone over Supported Palladium Catalysts

2016 ◽  
Vol 11 (3) ◽  
pp. 354 ◽  
Author(s):  
Lihui Fan ◽  
Luyang Zhang ◽  
Yanming Shen ◽  
Dongbin Liu ◽  
Nasarul Wahab ◽  
...  
Keyword(s):  
Liquid Phase ◽  
Palladium Catalysts ◽  
Pd Nanoparticles ◽  
Moderate Amount ◽  
Supported Palladium Catalysts ◽  
Phenol Hydrogenation ◽  
Liquid Phase Hydrogenation ◽  
Supported Palladium ◽  
Phenol Conversion ◽  
Supported Pd

<p>The ZSM-5, g-Al<sub>2</sub>O<sub>3</sub>, SiO<sub>2</sub> and MgO supported Pd-catalysts were prepared for the phenol hydrogenation to cyclohexanone in liquid-phase. The natures of these catalysts were characterized by XRD, N<sub>2</sub> adsorption-desorption analysis, H<sub>2</sub>-TPR, CO<sub>2</sub>-TPD and NH<sub>3</sub>-TPD. The catalytic performance of the supported Pd-catalyst for phenol hydrogenation to cyclohexanone is closely related to nature of the support and the size of Pd nanoparticles. The Pd/MgO catalyst which possesses higher basicity shows higher cyclohexanone selectivity, but lower phenol conversion owing to the lower specific surface area. The Pd/SiO<sub>2</sub> catalyst prepared by precipitation gives higher cyclohexanone selectivity and phenol conversion, due to the moderate amount of Lewis acidic sites, and the smaller size and higher dispersion of Pd nanoparticles on the surface. Under the reaction temperature of 135 <sup>o</sup>C and H<sub>2</sub> pressure of 1 MPa, after reacting for 3.5 h, the phenol conversion of 71.62% and the cyclohexanone selectivity of 90.77% can be obtained over 0.5 wt% Pd/SiO<sub>2</sub> catalyst. Copyright © 2016 BCREC GROUP. All rights reserved</p><p><em>Received: 7<sup>th</sup> March 2016; Revised: 13<sup>rd</sup> May 2016; Accepted: 7<sup>th</sup> June 2016</em></p><p><strong>How to Cite:</strong> Fan, L., Zhang, L., Shen, Y., Liu, D., Wahab, N., Hasan, M.M. (2016). Liquid-phase Hydrogenation of Phenol to Cyclohexanone over Supported Palladium Catalysts. <em>Bulletin of Chemical Reaction Engineering &amp; Catalysis</em>, 11 (3): 354-362 (doi: 10.9767/bcrec.11.3.575.354-362)</p><p><strong>Permalink/DOI</strong>: <a href="http://doi.org/10.9767/bcrec.11.3.575.354-362">http://doi.org/10.9767/bcrec.11.3.575.354-362</a></p>

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