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The effect of hydrogen partial pressure on methylcyclopentane ring opening

Journal Article · · Journal of Catalysis
; ;  [1]
  1. Eindhoven Univ. of Technology (Netherlands); and others
The ring opening of methylcyclopentane (MCP) over well-characterized Pt/SiO{sub 2} (EUROPT-1), Pt/{gamma}-Al{sub 2}O{sub 3}, and Pt/K-LTL catalysts was studied as a function of hydrogen partial pressure and reduction temperature. The MCP ring opening selectivity did not change in the range of H{sub 2}:MCP ratios studied (8-200). The turnover frequency (TOF) went through the maximum as the H{sub 2}:MCP ratio increased. The maximum TOF of the Pt/{gamma}-Al{sub 2}O{sub 3} after reduction at 450{degrees}c is about three times higher than the maximum specific activity of the Pt/K-LTL and Pt/SiO{sub 2} catalysts. The H{sub 2}:MCP partial pressure ratio at which maximum activity is obtained increases in the series Pt/K-LTL < Pt/{gamma}-Al{sub 2}O{sub 3} < Pt/SiO{sub 2}. This sequence is rationalized using reported adsorption energies of H{sub 2} and assuming a decreased adsorption energy of MCP on Pt/K-LTL. The data can be described with a reaction mechanism that includes the cleavage of a C-C bond as the rate-determining step. Kinetic analysis of the changes in specific reaction rate as a function of the H{sub 2}:MCP ratio showed that the reaction proceeds through multiple adsorbed MCP species. The surface reaction rate is more than an order of magnitude higher for the Pt/{gamma}-Al{sub 2}O{sub 3} catalyst than for the Pt/K-LTL catalyst, but decreases with increasing reduction temperature for both catalysts. 36 refs., 5 figs., 4 tabs.
OSTI ID:
175720
Journal Information:
Journal of Catalysis, Journal Name: Journal of Catalysis Journal Issue: 2 Vol. 151; ISSN 0021-9517; ISSN JCTLA5
Country of Publication:
United States
Language:
English