Recent Advances in Catalysts and Membranes for MCH Dehydrogenation: A Mini Review

Abstract

Methylcyclohexane (MCH), one of the liquid organic hydrogen carriers (LOHCs), offers a convenient way to store, transport, and supply hydrogen. Some features of MCH such as its liquid state at ambient temperature and pressure, large hydrogen storage capacity, its well-known catalytic endothermic dehydrogenation reaction and ease at which its dehydrogenated counterpart (toluene) can be hydrogenated back to MCH and make it one of the serious contenders for the development of hydrogen storage and transportation system of the future. In addition to advances on catalysts for MCH dehydrogenation and inorganic membrane for selective and efficient separation of hydrogen, there are increasing research interests on catalytic membrane reactors (CMR) that combine a catalyst and hydrogen separation membrane together in a compact system for improved efficiency because of the shift of the equilibrium dehydrogenation reaction forwarded by the continuous removal of hydrogen from the reaction mixture. Development of efficient CMRs can serve as an important step toward commercially viable hydrogen production systems. The recently demonstrated commercial MCH-TOL based hydrogen storage plant, international transportation network and compact hydrogen producing plants by Chiyoda and some other companies serves as initial successful steps toward the development of full-fledged operation of manufacturing, transportation and storage of zero carbon emission hydrogen in the future. There have been initiatives by industries in the development of compact on-board dehydrogenation plants to fuel hydrogen-powered locomotives. This review mainly focuses on recent advances in different technical aspects of catalytic dehydrogenation of MCH and some significant achievements in the commercial development of MCH-TOL based hydrogen storage, transportation and supply systems, along with the challenges and future prospects.

Chemical material as a hydrogen energy carrier: A review

“…Therefore, optimization studies for LOHC-based hydrogen storage and transportation systems are actively conducted worldwide, and demonstration projects are underway to integrate LOHC systems with existing hydrogen infrastructure. However, continuous research and development efforts are needed due to the relatively low hydrogen density and availability compared to other hydrogen storage compounds (such as methanol and ammonia) [124,[128][129][130][131][132][133][134][135]. Various LOHCs based on substances including benzene and toluene have been researched, and their characteristics are summarized in Table 5 [126].…”

“…Consequently, it indicates that catalysts may exist in various carbide forms with different carbon contents under LOHC dehydrogenation conditions, and structural changes in catalyst nanoparticles are highly reversible. Other types and characteristics of LOHCs and catalysts are summarized in Table 6 [124,[131][132][135][136][138][139][140][141][142][143][144][145][146]. Additionally, a comparative analysis of the technology and economic prospects of hydrogenation systems using high-density storage technologies and liquid organic hydrogen carriers (primarily ammonia or methanol) for large-scale hydrogen storage was conducted.…”

Design of Mixed Ionic-Electronic Materials for Permselective Membranes and Solid Oxide Fuel Cells Based on Their Oxygen and Hydrogen Mobility

“…The environmentally and economically efficient production of hydrogen and syngas for the above-mentioned polygeneration systems [ 27 ] and the dominant strategy to reduce the operating temperature of SOFCs [ 28 ] require the development of high-performance construction materials. They can be used for the design of electrodes [ 29 , 30 , 31 , 32 , 33 , 34 , 35 ] and electrolytes [ 36 , 37 , 38 , 39 , 40 , 41 ] in SOFCs and for the design of gas separation membranes [ 42 , 43 , 44 , 45 , 46 ] as well as in catalytic membrane reactors [ 47 , 48 , 49 ]. Oxide materials with mixed ionic-electronic conductivity (or mixed ionic electron conductors, MIECs) are considered as a prospective class of multifunctional materials and are widely investigated for their use in both SOFCs and membrane reactors [ 50 , 51 , 52 , 53 , 54 , 55 , 56 ].…”

Catalytic Dehydrogenation of Liquid Organic Hydrogen Carrier Model Compounds by CpM+ (M = Fe, Co, Ni) in the Gas Phase

“…7,8 Others that are viable on the industrial scale include perhydro-dibenzyl toluene/dibenzyl toluene 9,10 and methylcyclohexane/toluene. 11,12 Although the cyclohexane/benzene system (eq 1) is not very useful in the context of scaling up owing to the carcinogenic properties of benzene, it is often used as a model due to its relatively easy access to mechanistic studies and has been investigated in the context of reactant/product separation. 13,14 N-Heterocycle 15 couples such as piperidine/pyridine (eq 2, and derivatives), 16 octahydroindole/indole, 17 and perhydrophenazine/phenazine 18 (eq 3) are all viable substrates for stable hydrogen storage.…”

“…Cyclic alkanes and N-heterocyclic species are of special interest due to their stability and high energy density. Cycloalkane LOHC systems such as cyclohexane/benzene are good models for mechanistic studies. , Others that are viable on the industrial scale include perhydro-dibenzyl toluene/dibenzyl toluene , and methylcyclohexane/toluene. , Although the cyclohexane/benzene system (eq ) is not very useful in the context of scaling up owing to the carcinogenic properties of benzene, it is often used as a model due to its relatively easy access to mechanistic studies and has been investigated in the context of reactant/product separation. , N-Heterocycle couples such as piperidine/pyridine (eq 2, and derivatives), octahydroindole/indole, and perhydrophenazine/phenazine (eq 3) are all viable substrates for stable hydrogen storage. N-Heterocycles have the added benefits of relatively better biodegradability, low volatility, and more efficient hydrogen liberation …”