Understanding platinum-based H2 adsorption/ desorption kinetics during catalytic hydrogenation or hydrogen storage-related reactions

Hydrogen is among the most promising energy carriers and plays an important role on the way to sustainable technologies. Platinum holds great promise for unlocking the potential of renewable hydrogen, as it is an essential component of proton exchange membrane technologies and in various hydrogenation reactions. For the variety of applications of energy harvesting, conversion, and storage, the optimization and reduction of Pt loading is crucial. In view of this, a platinum catalyst using a stable SiO2 support is synthesized to investigate the adsorption/desorption behavior of hydrogen on platinum nanoparticles of different sizes, obtained by treating the sample at different calcination temperatures. Pulsed chemisorption and subsequent temperature-programmed desorption are described mathematically to obtain kinetic parameters. It is shown that higher adsorption capacities could be obtained using smaller particles. However, for particles smaller than 2.4 nm, higher Pt2+ content decreases H2 adsorption. Adsorption inhibition due to the presence of monatomic Pt cannot be excluded. The size of the Pt nanoparticles does not significantly affect the desorption/adsorption energy, but there is evidence that the hydrogen adsorbed per Pt atom at the surface varies with size: about 1 for single crystal planes and 2 for nanoparticles <3 nm.