Kinetics for the Isomerization of Methylcyclopentane on ZSM-5 in the Liquid Phase

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We have carried out a detailed and systematic study to derive a quantitative understanding for the mechanism of the liquid-phase reaction of methylcyclopentane on ZSM-5 catalyst in a stirred batch reactor and at five temperatures between 110 and 175°C. The rate constants (k) and catalyst deactivation (k_d) were obtained on the basis of the cyclohexane by a ring-expansion of methylcyclopentane with the selectivity of 92% or over. The rate of deactivation of ZSM-5 is as large as about 100 times of an activation rate. The activation parameters for the isomerization of methylcyclopentane are ΔH^‡ = 11.87 kcal/mol and ΔS^‡ = −55.9 cal/(mol K). As the conversion increases, the yields of 2-methylpentane and cyclohexane are linearly increased, but those of 3-methylpentane and C₅- are sharply and nonlinearly increased. The scheme of methylcyclopentane reaction over ZSM-5 is as follows: MCP → CH (main reaction) or 2-MP → 3-MP or C₅-. Higher reaction temperature favors cracking reaction (ring opening or cracked micromolecules) against the isomerization by a ring expansion.