Formic acid dehydrogenation over PtRuBiOx/C catalyst for generation of CO-free hydrogen in a continuous-flow reactor

Liquid-phase formic acid dehydrogenation using a solid carbon supported PtRuBiOx catalyst offers a promising and convenient method to produce CO-free hydrogen. In this study, the regenerability of the catalyst and the kinetics of formic acid dehydrogenation were investigated in a continuous-flow reactor. The kinetic experiments were carried out at temperatures between 300 and 333 K and formic acid concentrations ranging from 1.3 to 8.0 mol/L. It was found that an Arrhenius temperature dependence of the kinetic constant could represent the kinetics of formic acid dehydrogenation over the catalyst. The kinetics had first-order dependence for HCOO− and half-order with respect to HCOOH under the investigated conditions. The average apparent activation energy was determined to be about 38.1 kJ/mol, which is close to the previous value (37.3 kJ/mol) obtained in a batch reactor. To gain more insight into the formic acid dehydrogenation over the catalyst, two possible mechanisms with adsorption of HCOOH or HCOO− were proposed based on the experimental results and available information in literature. Two kinetic expressions were derived from the proposed reaction mechanisms. The corresponding kinetic parameters were estimated and further correlated with the apparent activation energies obtained at different formic acid concentrations.