Liquid organic hydrides are regarded as promising for use as hydrogen carriers via the methylcyclohexane (MCH)–toluene–hydrogen cycle. Because of the endothermic nature of MCH dehydrogenation, the reaction is usually conducted at temperatures higher than 623 K. In this work, low-temperature catalytic MCH dehydrogenation was demonstrated over 3 wt% Pt/CeO _(2) catalyst by application of electric field across a fixed-bed flow reactor. Results show that a high conversion of MCH beyond thermodynamic equilibrium was achieved even at 423 K. Kinetic analyses exhibited a positive correlation of hydrogen to the reaction rates and an “inverse” kinetic isotope effect (KIE), suggesting that accelerated proton hopping with the H atoms of MCH promotes the reaction. Operando analyses and DFT calculation proved that the reverse reaction ( i.e. toluene hydrogenation) was suppressed by the facilitation of toluene desorption in the electric field. The electric field promoted MCH dehydrogenation by surface proton hopping, even at low temperatures with an irreversible pathway.
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机译：液态有机氢化物被认为有望通过甲基环己烷（MCH）-甲苯-氢循环用作氢载体。由于MCH脱氢的吸热性质，该反应通常在高于623 K的温度下进行。在这项工作中，通过施加电场，证明了在3 wt％Pt / CeO _（2）催化剂上进行了低温催化MCH脱氢。穿过固定床流动反应器。结果表明，即使在423 K时，MCH仍能实现超过热力学平衡的高转化率。动力学分析显示氢与反应速率呈正相关，并且具有“逆”动力学同位素效应（KIE），这表明氢加速了质子跳跃MCH的原子促进反应。 Operando分析和DFT计算证明，通过在电场中促进甲苯的解吸，可以抑制逆反应（即甲苯加氢）。即使在低温下具有不可逆的路径，电场也通过表面质子跳跃来促进MCH脱氢。
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