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Toluene hydrogenation reaction for methylcyclohexane (MCH) synthesis via Pt-loaded Al2O3 and TiO2 (Pt/ Al2O3 and Pt/TiO2) catalysts were investigated in a fixed bed reactor at 398-473 K and ambient pressure. Partial pressures of toluene, hydrogen and MCH were 60 to 91, 9 to 23, and 9 to 17 kPa, respectively. Pt-loaded catalysts showed higher activities in the order of Pt/Al2O3 Pt/TiO2 (anatase-rutile mixture, AR) Pt/TiO2 (anatase, A) Pt/TiO2 (rutile, R) above 423 K, whereas Pt/TiO2 (anatase) showed remarkably higher activities at 393 K. To estimate the effects of support species, kinetic analysis using rate-based model was conducted. The correlation between adsorption behavior and catalytic activities was investigated using a Langmuir-Hinshelwood model. The kinetic constants for each catalyst were almost same. It was considered that only kinetic constants cannot explain the catalytic activities. Coverage of toluene and MCH were independent of the reaction rates, however the reaction rates increased as hydrogen coverage increased for all catalysts.

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Methylcyclohexane (MCH) is a candidate liquid organic hydrogen carrier for the storage of renewable energy. The by-products were examined in dehydrogenation and hydrogenation of the MCH/toluene (TOL) pair that forms an energy storage and release system. Pt catalyst was used for the dehydrogenation of MCH, and Ni catalysts were used for the hydrogenation of TOL, and 10 cycles of dehydrogenation/hydrogenation were conducted. Conversion of TOL to MCH greater than 97 % across all cycles, and conversion of MCH to TOL decreased from 90 to 84 %, with increasing cycle number. The original MCH feed contained 0.6 % impurities, and the concentration of by-products ranged from 0.7-0.9 %. More than 70 by-products were identified in the liquid product, and were categorized as the products of six types of side reactions: demethylation, ring-opening, isomerization to form 5-or 6-membered ring compounds, dimerization, and polycyclic compound formation. Demethylation compounds showed remarkable accumulation after 10 cycles.