Hydrogen Evolution from Additive-Free Formic Acid Dehydrogenation Using Weakly Basic Resin-Supported Pd Catalyst

Hydrogen, as a noncarbon energy source, plays a significant role in future clean energy vectors. However, concerns about the safe storage and transportation of hydrogen gas limit its wide application. Featured with high H₂ volumetric density, nontoxicity, and nonflammability, formic acid (FA) is regarded as one of the most encouraging chemical hydrogen carriers. The search for heterogeneous catalysts with decent catalytic activity and stability for FA decomposition is one of the hottest research topics in this area. In this paper, three weakly basic resins with different functional groups, including D201 with -N⁺(CH₃)₃, D301 with -N(CH₃)₂, and D311 with -NH₂, were investigated as alternative catalyst supports for Pd catalysts. The prepared basic resin-supported Pd catalysts were evaluated for the FA dehydrogenation reaction under atmospheric pressure and temperatures ranging from 30 to 70 °C. The results showed that the catalytic activity of the three different resin-supported Pd catalysts follows the order of Pd/D201 > Pd/D301 > Pd/D311. Particularly, a high turnover frequency value of 547.6 h^-1 was achieved when employing Pd/D201 as the FA dehydrogenation reaction catalyst at 50 °C. The apparent activation energies for the three different Pd/resin catalysts were calculated, of which the Pd/D210 catalyst demonstrates the lowest activation energy of 42.9 kJ mol^-1. The reasons for the superior catalytic behavior, together with the reaction mechanism, were then investigated and illustrated.