Selective Formic Acid Decomposition for High-Pressure Hydrogen Generation: A Mechanistic Study

A homogenous catalytic system has been developed that efficiently and selectively decomposes formic acid into hydrogen and carbon dioxide. [Ru(H2O)6]2+, [Ru(H2O)6]3+ and RuCl3·xH2O are all excellent precatalysts in presence of TPPTS (TPPTS=meta-trisulfonated triphenylphosphine), the formic acid decomposition taking place in the aqueous phase, under mild conditions and over a large range of pressures. Optimisation of the reaction conditions is described together with a detailed mechanistic study leading to a tentative catalytic cycle. The performance of the catalytic system for continuous hydrogen generation is presented. Overall, the method proposed overcomes the limitations of other catalysts for the decomposition of formic acid making it a viable hydrogen-storage material.