On-site catalytic dehydrogenation of methylcyclohexane: mechanisms, catalysts, advances, and prospects†

The storage and transport of hydrogen in the form of chemicals, such as ammonia, methanol, and liquid organic hydrogen carrier (LOHC), has emerged as a promising technology as they can be stored under milder conditions than compressed hydrogen and liquefied hydrogen. Methylcyclohexane (MCH)–toluene (TOL) emerged as a prominent LOHC system with moderate melting point, hydrogen capacity, and mild storage conditions. This review provides an overview of existing hydrogen storage technologies, followed by a focused discussion different LOHC systems, with an emphasis on MCH as a promising LOHC, its dehydrogenation reaction mechanism and the performance of the available catalysts. The purpose of this review is to critically assess the latest developments regarding the catalytic dehydrogenation of MCH. The effects of various catalysts and operating conditions on the dehydrogenation performance of MCH, coupled with technical, economic, and environmental perspectives of the MCH-based hydrogen supply chain, were presented. This work also highlights the obstacles associated with using MCH as a hydrogen carrier for on-site dehydrogenation at fuel stations. Additionally, this review discusses the current stage of commercialisation of MCH as a hydrogen carrier in the Asia-Pacific region.