Conversion of methylcyclopentane (MCP) on Pt/MoO2, Ir/MoO2 and Pt-Ir/MoO2 catalysts

The effect of the metal and reaction temperature was investigated in the conversion of MCP with hydrogen at atmospheric pressure. The highly dispersed 0.5 wt.% Pt/MoO2, 0.5 wt.% Ir/MoO2 and 0.25 wt.%-025 wt.% Pt-It/MoO2 metal catalysts were prepared by incipient wetness impregnation or co-impregnation methods. The most active catalyst in the conversion of MCP was Pt/MoO2 and the most selective to MCP ring opening was Ir/MoO2. At low temperature, Ir/MoO2 opened the MCP ring at the secondary-secondary position. High temperature promoted ring opening at the secondary-tertiary positions, which was attributed to the adlineation sites. At low temperatures, Pt/MoO2 and Pt-Ir/MoO2 promoted only the ring enlargement reaction while Ir/MoO2 promoted both ring opening and ring enlargement. Ring enlargement of MCP to cyclohexane and benzene was catalysed by electron deficient adduct sites, while ring opening to 2-meythylpentane (2-MP), 3-methylpentane (3-MP) and n-hexane (n-H) was catalysed by metallic sites. At high temperatures, MCP broken into C-1-C-5 fragments and deactivation of the catalysts was observed. The Ir/MoO2 showed the highest selectivity for cracking. The differences in selectivity were attributed to the presence of adsorbed agostic species, where the electronic environment of Ir and Pt are different. (C) 2011 Elsevier B.V. All rights reserved.