Effect of Ca, Ce or K oxide addition on the activity of Ni/SiO₂ catalysts for the methane decomposition reaction

To increase the activity and stability of Ni/SiO₂ catalysts, a series of Ni-Ca, Ni-K and Ni-Ce promoted catalysts were prepared by successive impregnations. The textural properties, reducibility and catalytic performance in the methane decomposition reaction were investigated. The catalyst containing 30 wt.% Ni and 30 wt.% cerium oxide greatly increased the conversion of methane (90% of equilibrium value) and improved the stability, whereas the Ni-K and Ni-Ca were less active and stable than the Ni/SiO₂ catalyst. The results suggest that Ce addition prevents the sintering of nickel particles during reduction process maintaining a random distribution between the silica and cerium oxide improving the distribution and migration of deposited carbon.