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.%–0.25 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 C1–C5 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.

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► The most active catalyst in the conversion of MCP was Pt/MoO2.
► The most selective to MCP ring opening was Ir/MoO2.
► At low temperature Pt/MoO2 and Pt–Ir/MoO2 promoted only the ring enlargement reaction.
► At low temperature Ir/MoO2 promoted both ring opening and ring enlargement.