The catalytic effect of Ni in methane pyrolysis using molten SnNi alloys for hydrogen production

Hydrogen has a high potential to decarbonize our economy, particularly the industry, which can only be accomplished if its production is both sustainable and economically viable. In this context, methane pyrolysis is a promising alternative as the base reaction emits zero greenhouse gases. However, the underlying fundamental principles of turquoise hydrogen synthesis require further research for a better understanding of the rate-limiting mechanisms. This work investigates methane pyrolysis in a liquid-metal bubble column reactor and focuses on the efficiency of Sn and four different molten SnNi alloys. A kinetic model approximating these conditions was developed to investigate the effect of Ni. The evaluation of the experimental data determined the activation energies of the methane pyrolysis reaction to be in the range between 204.51 and 335.74 kJ/mol. Adding nickel to tin resulted in a nearly linear decrease in EA. We concluded that the physical properties of the melt, such as viscosity and surface tension, are the dominant influencing factors at high temperatures, while nickel is especially interesting in designated low-temperature pyrolysis reactors.