Generating electricity from MCH using solid oxide fuel cells

A team of researchers from Waseda University in Japan have successfully generated electricity directly from methylcyclohexane (MCH), an organic hydride, using solid oxide fuel cells, with lower energy than conventional catalytic dehydrogenation reactions. Methylcyclohexane is promising as a hydrogen carrier that can safely and efficiently transport and store hydrogen. However, the dehydrogenation process using catalysts has issues due to its durability and large energy loss. The research published by scientists from Waseda University is expected to reduce energy requirements and explore new chemical synthesis by fuel cells.

MCH, a type of organic hydride, is expected to be an excellent hydrogen carrier because it remains liquid at room temperature, is easy to transport, has low toxicity, and has a higher hydrogen density than high-pressure hydrogen. Dehydrogenation — the process of removing hydrogen atoms from molecules — in the presence of a catalyst, yields hydrogen and the by-product toluene, which can be used to generate electricity to produce CO₂-free power. However, the dehydrogenation reaction is an endothermic reaction, and energy loss as well as the facilities required for the reaction, are issues.

The researchers tried to perform two processes simultaneously in a fuel cell: dehydrogenation from organic hydrides, which is an endothermic reaction, and electricity generation, which is an exothermic reaction. To achieve this, they used an anode-supported solid oxide fuel cell with a higher operating temperature than that of a polymer electrolyte fuel cell. They operated it at a temperature that did not allow pyrolysis of organic hydrides and under conditions that prevented carbon deposition at the electrodes. The production ratio of toluene to benzene was 94:6. This development demonstrates the possibility of generating electricity without using dehydrogenation facilities which were conventionally required and using less energy than that required for dehydrogenation reactions using catalysts.

The researchers found that by changing the conditions, oxygen groups could be introduced into the aromatic skeleton using a fuel cell. These results indicate that the MHC reacts with the conducting oxygen ions in the solid oxide fuel cells to generate electricity. Thus, power can be generated directly from MHC, and the energy required for direct power generation is lesser than that required for the conventional catalyst-assisted dehydrogenation reaction of MCH.

The research findings were published in the journal Applied Energy.

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