Selective dehydrogenation of aqueous formic acid over multifunctional γ-Mo2N catalysts at a temperature lower than 100 ℃

Efficient and selective dehydrogenation of aqueous formic acid (FA) for hydrogen production with non-noble-metal-based heterogeneous catalysts remains a great challenge. Herein, complete dehydrogenation of aqueous FA with a concentration as high as 40 vol% achieved a gas production rate of 293.9 mL/gcat./h by using a biomass-derived multifunctional γ-Mo2N catalyst synthesized with a facile pyrolysis process. No significant deactivation of catalysts was found during the 108 h-stability-test. Mechanism investigations indicate that the solvent H2O could occupy the Brønsted acid sites to prevent FA dehydration. The dehydrogenation activity was significantly improved by the cooperation of K-containing sites, N-doped sites, and the γ-Mo2N active sites, which could be responsible for the HCOO− intermediate generation and adsorption, H+ adsorption, and H-C bond cleavage of the adsorbed HCOO−, respectively. This study provided a novel strategy to improve the dehydrogenation performance of aqueous FA with non-noble-metal-based heterogeneous catalysts.