Ni-based catalyst over rice husk-derived silica for the CO2 methanation reaction: Effect of Ru addition

Amorphous, high purity and sulfur-free silica was obtained from rice husk, which was used as support in metal catalysts. Ni and Ni-Ru catalysts were synthesized by wet impregnation over SiO2. The metallic loading was varied keeping the Ru/Ni ratio equal to 0.1. The solids were characterized by different techniques such as XRD, FT-IR, N2 adsorption, XRF, HRTEM, EDX, Raman, TPR, H2-TPD and XPS. They were evaluated in the CO2 methanation reaction between 250 and 400 °C. The rice husk-derived silica allowed obtaining Ni-based catalysts more suitable for CO2 methanation than commercial fumed silica. The incorporation of low amounts of Ru into Ni-based catalysts decreased particle size and improved the reducibility of NiO as well as the H2 adsorption capacity. The catalysts were active and stable. The Ni5Ru solid resulted the most promising catalyst for the CO2 methanation reaction by achieving the highest methane production rate with the lowest metal loading. [Display omitted] •Amorphous, high purity and sulfur-free silica was obtained from rice husk.•Ni and Ni-Ru catalysts were synthesized by wet impregnation over SiO2.•The incorporation of low amounts of Ru into Ni catalysts decreased particle size.•Ru addition improved the reducibility of NiO as well as the H2 adsorption capacity.•The Ni5Ru solid resulted the most promising catalyst for the CO2 methanation reaction.