Kinetic Model of the Dehydrogenation of Methylcyclohexane over Monometallic and Bimetallic Pt Catalysts

Ind. Eng. Chem. Res., 2011, 50 (5), pp 2509–2522
Kinetic Model of the Dehydrogenation of Methylcyclohexane over Monometallic and Bimetallic Pt Catalysts
Faisal Alhumaidan*†, David Cresswell‡, and Arthur Garforth‡
fhumaidan@prsc.kisr.edu.kw
† Petroleum Research and Studies Center, Kuwait Institute for Scientific Research, P.O. Box 24885, Safat 13109, Kuwait
‡ Environmental Technology Center, School of Chemical Engineering and Analytical Science, The University of Manchester, P.O. Box 88, Sackville St., Manchester M60 1QD, U.K.
Abstract
Kinetic models were developed for methylcyclohexane (MCH) dehydrogenation over supported Pt catalysts.
The best fitting mechanistic model is of the non-Langmuirian/noncompetitive Horiuti-Polanyi type. The Horiuti-Polanyi aromatic hydrogenation mechanism in this model, which assumes an atomic hydrogen addition to aromatics on the catalyst surface, is applied in reverse to MCH dehydrogenation. Additionally, the model assumes that hydrogen and MCH molecules adsorb noncompetitively on two different types of sites to accommodate observed near zero-order dependence of reaction rate on MCH and the negative order dependence upon hydrogen. A non-Langmuirian adsorption isotherm is adopted to account for the increase in the hydrogen inhibition effect with pressure. The reversible and irreversible deactivation kinetics are satisfactorily included in the kinetic model.
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