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 KINETICS OF HYDROGENATION OF NITROBENZENE, 4-NITROTOLUENE, 4-NITROANILINE AND 2-CHLORO-4-NITROANILINE ON SUPPORTED PALLADIUM CATALYST

2018 ◽  
Vol 59 (4) ◽  
pp. 68
Author(s):  
Alexander A. Krasnov ◽  
Adele R. Latypova ◽  
Olga V. Lefedova ◽  
Nikolaiy Yu. Sharonov ◽  
Evgeniy V. Efremov ◽  
...  
Keyword(s):  
Liquid Phase ◽  
Aqueous Solutions ◽  
Nitro Compound ◽  
Palladium Catalyst ◽  
Reaction Rate ◽  
Supported Palladium Catalyst ◽  
Liquid Phase Hydrogenation ◽  
Donor Acceptor ◽  
Supported Palladium ◽  
Kinetics Of

A study of the kinetics of liquid phase hydrogenation of nitrobenzene, 4-nitrotoluene, 4-nitroaniline and 2-chloro-4-nitroaniline on supported palladium catalyst in aqueous solutions of 2-propanol of different composition was carried out. The influence of the substituent on the value of the total amount of hydrogen absorbed during the reaction and the kinetics of the hydrogenation of substituted nitrobenzenes was discussed. It was found out that the reaction selectivity to 2-chloro-1,4-phenylenediamine decreases due to by-reaction dehalogenation. The degree of dehalogenation depends on the composition of solvent and may be approximately estimated by the values of the absorbed hydrogen volume during the reaction. Also, the presence of the donor-acceptor substituents is capable of exerting influence on the reaction rate of hydrogenation of the nitro compound.

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>

scholarly journals KINETICS OF 2-CHLORO-4-NITROANILINE HYDROGENATION OVER SUPPORTED PLATINUM AND PALLADIUM CATALYSTS IN WATER SOLUTION OF 2-PROPANOL

2017 ◽  
Vol 61 (1) ◽  
pp. 42
Author(s):  
Adele R. Latypova ◽  
Alexander A. Krasnov ◽  
Nickolay Yu. Sharonov ◽  
Ikfat M. Safarov ◽  
Olga V. Lefedova
Keyword(s):  
Liquid Phase ◽  
Palladium Catalysts ◽  
Water Solution ◽  
Platinum Catalysts ◽  
Physicochemical Characteristics ◽  
Liquid Phase Hydrogenation ◽  
Supported Platinum ◽  
The Relationship ◽  
Kinetics Of ◽  
Structure And Activity

The kinetics of liquid-phase hydrogenation of 2-chloro-4-nitroaniline over supported platinum and palladium catalysts in the aqueous solution of 2-propanol (0.68 mole fraction) was studied. Dependences of changes in concentration of participants vs the reaction time was obtained. The orders of reaction with respect to hydrogen and initial reagent were zero and the first. The palladium catalysts in comparison with platinum catalysts absorbed more amount of hydrogen. The products of dehalogenation reaction are main by-products. The platinum catalysts, as rules, more active in the conversion of the nitro group and selective with respect to chloroamine. The chloroaniline hydrogenation over the studied catalysts proceeded on sequential scheme. So, the chloroamine was dehalogenated. The values of the rate constants for all catalyst samples were varied depending on the total metal content. It was found that low-percentage platinum catalysts allow to achieve high selectivity of hydrogenation of HNC with respect to CFDA while maintaining the values of the observed rates of hydrogen absorption the similar as palladium catalysts. It is known that the kinetic regularities of catalytic reactions are associated with the structural and physicochemical characteristics of the catalysts. In particular, palladium and platinum have different electronic structures and behave is different in the catalytic reaction. Structure characteristics have value for the reaction kinetics also. The obtained data are consistent with these facts. However, some assumption appeared, that when the nature of the solvent varies, the same catalyst can behave differently. So, determination the relationship between the structure and activity of the catalyst only is not sufficiently correct for liquid-phase systems, without including the effect of the nature of the solvent.Forcitation:Latypova A.R., Krasnov A.I., Sharonov N.Yu., Safarov I.M., Lefedova O.V. Kinetics of 2-chloro-4-nitroaniline hydrogenation over supported platinum and palladium catalysts in water solution of 2-propanol. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2018. V. 61. N 1. P. 42-48

scholarly journals SUPPORTED PALLADIUM CATALYSTS FOR SELECTIVE LIQUID-PHASE HYDROGENATION OF AROMATIC NITRO COMPOUNDS

2021 ◽  
Vol 14 (03) ◽  
pp. 1795-1802
Author(s):  
L.R. Sassykova ◽  
A.R. Sassykova ◽  
B.T. Dossumova ◽  
M. S. Ilmuratova ◽  
N. E. Maximov ◽  
...  
Keyword(s):  
Liquid Phase ◽  
Palladium Catalysts ◽  
Nitro Compounds ◽  
Supported Palladium Catalysts ◽  
Aromatic Nitro Compounds ◽  
Liquid Phase Hydrogenation ◽  
Supported Palladium ◽  
Aromatic Nitro
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