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Comparison of Selective Gas Phase- and Liquid Phase Hydrogenation of (Cyclo-)Alkadienes towards Cycloalkenes on Pd/Alumina Egg-Shell Catalysts

Wuchter, Nils and Schäfer, Peter and Schüler, Christiane and Gaube, Johann and Miehe, Gerhard and Fuess, Hartmut (2006):
Comparison of Selective Gas Phase- and Liquid Phase Hydrogenation of (Cyclo-)Alkadienes towards Cycloalkenes on Pd/Alumina Egg-Shell Catalysts.
In: Chemical Engineering & Technology, (12), 29. pp. 1487-1495, ISSN 09307516,
[Online-Edition: http://dx.doi.org/10.1002/ceat.200600237],
[Article]

Abstract

The hydrogenation of dienes such as 1,3-butadiene, cyclooctadiene, and of acetylenic hydrocarbons on Pd catalysts shows high reaction rates and consequently, a strong influence of mass transfer on the selectivity of the intermediate alkene or cycloalkene product. 100 % selectivity towards (cyclo)-alkene hydrogenation is achieved for the gas phase when the Thiele modulus is equation image, where L is the thickness of the active layer and Deff is the effective diffusion coefficient of the diene. The interdependencies expressed by this formula were studied in detail using model catalysts with regular pores of uniform length and diameter and perpendicular to the surface. These catalysts were prepared by anodic oxidation of aluminium wires and immobilization of the active Pd. For the liquid phase procedure of selective hydrogenation, a reaction mass transfer model has been derived in order to compare the gas phase and liquid phase procedures, in particular with respect to the selectivity. The hydrogenation of 1,3-cyclooctadiene and of 1,3-butadiene were studied for both procedures employing the same catalyst. The rate of hydrogenation can be represented for both cases by the identical kinetic equation r1 = k1 cH2. This result is interpreted by assuming that the access of hydrogen to the surface through the dense layer of adsorbed diene is the rate determining step.

Item Type: Article
Erschienen: 2006
Creators: Wuchter, Nils and Schäfer, Peter and Schüler, Christiane and Gaube, Johann and Miehe, Gerhard and Fuess, Hartmut
Title: Comparison of Selective Gas Phase- and Liquid Phase Hydrogenation of (Cyclo-)Alkadienes towards Cycloalkenes on Pd/Alumina Egg-Shell Catalysts
Language: English
Abstract:

The hydrogenation of dienes such as 1,3-butadiene, cyclooctadiene, and of acetylenic hydrocarbons on Pd catalysts shows high reaction rates and consequently, a strong influence of mass transfer on the selectivity of the intermediate alkene or cycloalkene product. 100 % selectivity towards (cyclo)-alkene hydrogenation is achieved for the gas phase when the Thiele modulus is equation image, where L is the thickness of the active layer and Deff is the effective diffusion coefficient of the diene. The interdependencies expressed by this formula were studied in detail using model catalysts with regular pores of uniform length and diameter and perpendicular to the surface. These catalysts were prepared by anodic oxidation of aluminium wires and immobilization of the active Pd. For the liquid phase procedure of selective hydrogenation, a reaction mass transfer model has been derived in order to compare the gas phase and liquid phase procedures, in particular with respect to the selectivity. The hydrogenation of 1,3-cyclooctadiene and of 1,3-butadiene were studied for both procedures employing the same catalyst. The rate of hydrogenation can be represented for both cases by the identical kinetic equation r1 = k1 cH2. This result is interpreted by assuming that the access of hydrogen to the surface through the dense layer of adsorbed diene is the rate determining step.

Journal or Publication Title: Chemical Engineering & Technology
Journal volume: 29
Number: 12
Divisions: 11 Department of Materials and Earth Sciences > Material Science > Structure Research
07 Department of Chemistry > Fachgebiet Technische Chemie
11 Department of Materials and Earth Sciences > Material Science
11 Department of Materials and Earth Sciences
07 Department of Chemistry
Date Deposited: 10 Jan 2011 13:28
Official URL: http://dx.doi.org/10.1002/ceat.200600237
Identification Number: doi:10.1002/ceat.200600237
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