Takise Kent, Sato Ayaka, Ogo Shuhei, Seo Jeong Gil, Imagawa Ken-Ichi, Kado Shigeru, Sekine Yasushi
Waseda University, Department of Applied Chemistry 3-4-1, Okubo, Shinjuku Tokyo 169-8555 Japan
Myongji University, Department of Energy Science and Technology 116 Myongji-ro Yongin-si Gyeonggi-do 17058 Republic of Korea.
RSC Adv. 2019 Sep 3;9(48):27743-27748. doi: 10.1039/c9ra06042a.
The methylcyclohexane (MCH)-toluene cycle is a promising liquid organic hydride system as a hydrogen carrier. Generally, MCH dehydrogenation has been conducted over Pt-supported catalysts, for which it requires temperatures higher than 623 K because of its endothermic nature. For this study, an electric field was applied to Pt/TiO catalyst to promote MCH dehydrogenation at low temperatures. Selective dehydrogenation was achieved with the electric field application exceeding thermodynamic equilibrium, even at 423 K. With the electric field, "inverse" kinetic isotope effect (KIE) was observed by accelerated proton collision with MCH on the Pt/TiO catalyst. Moreover, Pt/TiO catalyst showed no methane by-production and less coke formation during MCH dehydrogenation. DRIFTS and XPS measurements revealed that electron donation from TiO to Pt weakened the interaction between catalyst surface and π-coordination of toluene. Results show that the electric field facilitated MCH dehydrogenation without methane and coke by-production over Pt/TiO catalyst.
甲基环己烷（MCH）-甲苯循环作为一种氢载体，是一种很有前景的液体有机氢化物体系。一般来说，MCH脱氢反应是在负载型Pt催化剂上进行的，由于其吸热性质，该反应需要高于623 K的温度。在本研究中，对Pt/TiO催化剂施加电场以促进低温下的MCH脱氢反应。即使在423 K时，通过施加超过热力学平衡的电场也实现了选择性脱氢。在电场作用下，在Pt/TiO催化剂上观察到质子与MCH加速碰撞产生的“逆”动力学同位素效应（KIE）。此外，Pt/TiO催化剂在MCH脱氢过程中未产生甲烷副产物且积炭较少。漫反射红外傅里叶变换光谱（DRIFTS）和X射线光电子能谱（XPS）测量结果表明，TiO向Pt的电子给予作用减弱了催化剂表面与甲苯π配位之间的相互作用。结果表明，电场促进了Pt/TiO催化剂上MCH的脱氢反应，且无甲烷和积炭副产物生成。
