Production and Utilization of Hydrogen Carriers by Using Supported Nickel Catalysts

The Industrial Revolution improved both productivity and living standards, and fossil fuels have been used as the essential energy sources for human society. However, the resultant enormous consumption has induced serious environmental and energy issues. An increase in world population and an economic growth of developing countries have accelerated the consumption of the resources. Consequently, a new energy system independent of fossil fuels must be urgently developed1). Hydrogen has been widely considered as an alternative energy source since the commercialization of fuel cells. Hydrogen is presently produced by the reforming of fossil fuels. Thus, application of renewable energy to hydrogen production is required for the reduction of the dependence on fossil fuels. However, areas optimum for solar and wind energy production are often far from energy consumption areas, although present policies depend greatly on renewable energy for the realization of a low-carbon society. Therefore, conversion of these renewable energies to hydrogen is also desirable in terms of utilization on a large scale. Hydrogen has low boiling point and volumetric energy density, leading to great difficulties in the liquefaction and compression processes. Therefore, hydrogen carrier, compounds containing hydrogen, are possible solutions for the storage and transportation of hydrogen fuel. Such hydrogen carriers can be delivered to energy consumption areas, and reformed or decomposed to produce hydrogen2). Ammonia, methylcyclohexane, and methane are all potential candidates for hydrogen carriers because of the high hydrogen content, suitability for mass production, and ease in storage and transportation2). We have focused on methane synthesis from CO2 and hydrogen, and hydrogen production by ammonia decomposition. This review mainly introduces our recent research on these reactions using supported Ni catalysts.