Formic acid (FA) is considered as a promising liquid organic hydrogen carrier (LOHC). With FA’s properties, we concerned FA as the source of high-pressure CO2/H2 without any compressing procedures. In this presentation, we show the development of the continuous production of high-pressure H2 and CO2 over 150 MPa, and easy separation from the generated gases under high-pressure conditions. For the development of the high-pressure gas generation by the FA dehydrogenation, we used the Ir complex ([Cp*Ir(4,4’-dihydroxy-2,2’-bipyridine)(H2O)][SO4]) as a homogeneous catalyst. The catalyst can successfully produce the high-pressure gas with a high rate (TOF = 2500 h-1 at 30 MPa) at the temperature of 80oC. Whereas in the high-pressure conditions, the catalyst was deactivated gradually with decreasing the reaction rate. To overcome this, we developed higher durable catalyst by modification of the ligand, and the modified catalyst can generate high-pressure CO2/H2 for longer time. For the further development, we found that the iridium aqua complex coordinated with a pyridyl-imidazoline ligand showed the higher performances on the FA dehydrogenation at the pressure as high as 153 MPa (Fig. 1). We also demonstrated the high-pressure H2/CO2 gas separation by cooling the gas to change the supercritical to gas-liquid phase.1 Using our system, more than 99 mol% of H2 (96 mol% of purity) and 94 mol% of CO2 (99 mol% of purity) were separately obtained as a gas and liquid, respectively, under the high-pressure conditions. Ours system has a potential to be used as a simple and easy to handle system for the generation of high-pressure CO2 and H2 and these separated high-pressure gases can be used for the variety of application such as fuel cell vehicles.

150MPa of high-pressure H2/CO2 production by formic acid dehydrogenation and continuous separation

2019 Fall National Meeting

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