One of the central challenges of this century is the sufficient and sustainable supply of energy. In this respect, advancements in hydrogen technology, such as the generation of hydrogen from suitable starting materials, its storage and conversion into electrical energy, are of particular interest.1,2Besides methane and methanol, renewable resources, formic acid (FA) or fromate, is considered as promising source for hydrogen storage.3,4 Especially, formates are non-corrosive, nonirritating and easy to handle, as well as highly soluble in aqueous media. More importantly, the resulting aqueous bicarbonate solution can be catalytically recharged with hydrogen to a formate solution to close the storage/evolution cycle under much milder conditions than those required for reactions of methanol or methane. So the bicarbonate/ fromate equilibrium in aqueous solution has already been considered by many groups for hydrogen storage and evolution. 5,6Figure 1, Reversible H2 storage is achieved by switching the H2 pressure and reaction temperature in the bicarbonate/formate equilibrium systemHere, we describe the design of a reversible hydrogen storage-evolution process based on redox ammonium bicarbonate (or Carbamate)/formate equilibrium over the same Pd NPs catalyst. Our investigations indicate that NH4HCO3(or NH2CO2NH4)/ NH4HCO2 redox equilibrium is a promising reversible hydrogen storage and evolution system, and high yield of hydrogenation of NH4HCO3 and NH2CO2NH4 of and high conversion of NH4HCO2 could be gained over the Pd NPs catalyst. Reaction temperature and H2 pressure are key factors to control the reaction equilibrium. More than 95 % NH4HCO2 yield could be easily gained when the hydrogenation reaction carrying out at low temperature and high H2 pressure. And more than 90 % NH4HCO2 conversion could be gained when the dehydrogenation reaction conducting on relative high temperature and with 0.1 MPa N2 initial pressure. And the reaction mechanism and the effect of ammonium ion on the hydrogenation reaction were investigated. In contrast to the homogeneous catalytic reaction system, this heterogeneous catalytic process is more efficient and promising.

High efficent reversible hydrogen storage-evolution process based on redox ammonium bicarbonate (or carbamate)/formate equilibrium over Pd NPs catalyst

248th National Meeting (2014)

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