Formic acid is considered as one of the promising liquid hydrogen carrier for fuel cells to solve the increasing demand of energy using fossil fuel. However, hydrogen can be applied for the various industrial systems, it has very low volumetric energy density under atmospheric pressure that affects some technical difficulties including the storage issue, especially the feeding of high-pressure hydrogen. To overcome those problems, the compression of hydrogen by booster, liquefied hydrogen by super-cooler and the hydrogen absorption by porous materials have been developed. But those methods consumes a lot of energy to maintain the constant pressure, continuous feeding of hydrogen as well as the process safely. Recently, we reported the production of high-pressure gas of 123 MPa from formic acid by using Cp*Ir homogeneous catalysts having 4,4’-dihydroxy-2,2’-bipyridine ligand without any compressing procedures. However, a high rate (turnover frequency, TOF = 2500 h-1) was obtained and the generated carbon monoxide, undesired product for fuel cells, was below the detection limit of (5 ppm), the TOF at 30 MPa decreased about 1/4 of that at atmospheric pressure. To clarify its decreasing, we investigated the mechanism by reaction kinetics at various conditions, and found the reaction rate determining step is drastically changed. Furthermore, we also studied the catalyst decomposition mechanism under high-pressure conditions, and will show the strategy for the catalyst design and catalytic activity to improve the high-pressure hydrogen evolution from formic acid for the industrial use.

Development of continuous high-pressure hydrogen evolution from formic acid by Iridium homogeneous catalyst and its kinetic study under pressurized conditions

254th National Meeting (2017)

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