Abstract:

Developing highly efficient hydrogen storage technology plays a key role in large-scale hydrogen energy applications. As an ideal organic liquid hydrogen storage medium, methylcyclohexane (MCH) has the advantages of high mass hydrogen storage density, safe and convenient storage and transportation, etc. However, the dehydrogenation process still faces problems such as high reaction temperature and low efficiency. The key to solving the above problems is to develop efficient dehydrogenation catalysts and introduce effective process intensification. Herein, a series of N-doped porous carbon (NPC) with different calcination temperature supported Pt catalysts (Pt/NPC) were prepared by wet impregnation method, and their effects on the MCH dehydrogenation were studied by novel internal electric heating (IEH) mode. The results show that the Pt²⁺ proportion firstly increases and then decreases with the increment of the NPC calcination temperature, and reaches the maximum value at 550℃. An approximately linear positive correlation between the Pt²⁺ proportion and the reaction rate of MCH dehydrogenation is obtained. Moreover, the hydrogen evolution rate over optimized Pt/NPC catalyst under IEH mode was about 3 times of that under conventional external heating (CEH) mode. In combination with temperature measurements, the calculation of reaction heat and heat transfer, catalytic evaluation and operando MCH-FTIR characterization, the improved catalytic performance was ascribed to high heating rate and heat transfer rate, as well as strengthened MCH adsorption in the IEH mode. This work presents guidance for developing the novel catalytic reaction ways by IEH mode and designing corresponding high effective catalysts in hydrogen storage and other heterogeneous catalytic reaction processes.

Key words: methylcyclohexane dehydrogenation, hydrogen, carrier, catalyst, internal electric heating

摘要：

高效储氢技术研发是实现氢能规模化应用的关键。甲基环己烷（MCH）作为理想的有机液体储氢介质，具有质量储氢密度高、储运安全方便等优势，但其脱氢过程仍存在反应温度高、效率低等难题，开发高效脱氢催化剂并引入有效的过程强化是解决上述问题的关键。以不同焙烧温度得到的氮掺杂多孔碳（NPC）作为载体，通过浸渍法制备了系列NPC负载Pt的催化剂（Pt/NPC），在新型电内加热（IEH）模式下，研究了其对MCH脱氢反应性能的影响规律。研究结果表明，随着NPC焙烧温度的升高，Pt²⁺占比先增加后减少，并在550℃达到最大值。在MCH脱氢反应中，Pt²⁺占比与反应速率呈近似线性正相关。在优化的Pt/NPC催化剂上，IEH模式下的释氢速率约为传统外加热（CEH）模式的3倍。组合温度测量、反应热与传热计算、性能评价和原位红外表征结果阐明了IEH模式下高的加热速率与传热速率，以及增强的MCH吸附是提升催化性能的重要原因。本研究可为新型电内加热反应方式及与之相匹配高效催化剂的设计研发提供指导。

关键词: 甲基环己烷脱氢, 氢, 载体, 催化剂, 电内加热