Decoupling the size and support/metal loadings effect of Ni/SiO2 catalysts for CO2 methanation

CO2 methanation constitutes one of the most promising technologies for highly efficient CO2 utilization while reducing the emission of greenhouse gases. The active Ni-based catalysts show the size-dependent activity for this reaction; however, the Ni size effect was highly coupled with the effect of support or metal loadings. Herein, the effect of nickel particle size in the range of 3.5–7.5 nm on CO2 methanation has been investigated using constant Ni loading of 2 wt.% Ni/SiO2 catalysts based on inert silica support prepared by different methods. The catalyst with small Ni nanoparticle exhibited highly enhanced catalytic performance, illustrating that the performance of CO2 methanation can be improved by tuning the particle size of Ni supported on SiO2. In situ diffuse reflectance Fourier transform infrared spectroscopy (DRIFTS) results indicated that small Ni particle size is beneficial to the formation of initial monodentate carbonate and important intermediates such as monodentate formate and linearly adsorbed CO species which are highly in favor of CO2 methanation reaction. This work provides valuable guidelines for designing an effective CO2 methanation catalyst by tuning the size of Ni nanoparticles.