Development of Effective Catalysts for Hydrogen Storage Technology Using Formic Acid

Hydrogen has attracted considerable attention as an energy source, and various attempts to develop suitable methods for hydrogen generation are made at the National Institute of Advanced Industrial Science and Technology. In this paper, the authors introduce their recent strategies to store hydrogen using formic acid (FA) as a hydrogen carrier. FA, which is believed to be one of the most promising liquid organic hydrogen carriers, can provide a viable method for safe hydrogen transportation. In order to optimize the performance of hydrogen storage with FA, the authors have investigated both homogeneous and heterogeneous catalysts. For example, Ir catalysts anchoring (NN)-N-boolean AND-bidentate ligands show high catalytic activity for both the reactions of FA synthesis and hydrogen generation from FA. Ultrafine Pd-based nanoparticles are also immobilized on various supports, which show excellent catalytic performance for FA dehydrogenation under mild conditions. The authors also develop both homogeneous and heterogeneous catalysts to generate high-pressure gases (H-2 and CO2) over 120 and 35 MPa, respectively, from direct FA dehydrogenation without any compressing procedures. The generated high-pressure gases (H-2 and CO2) can be easily and simply separated by changing the fluid phase from the supercritical to gas-liquid phase by cooling without depressurization.