Enhanced reactive CO2 species formation via V2O5-promoted Ni/KCC-1 for low temperature activation of CO2 methanation

Application of CO2 methanation, especially in CO2-rich gas fields, could potentially provide additional value to the synthetic natural gas production. In this study, highly active vanadium (V2O5)-promoted Ni/KCC-1 catalysts with 5% nickel content were prepared using a co-impregnation method for CO2 methanation reaction. The influence of V2O5 on the textural properties, basicity and reducibility of the 5Ni/KCC-1 catalysts was systematically investigated. It was found that addition of V2O5 enhances the basicity of the catalysts; however, it decreases the surface area and pore volume. The amphoteric properties of V2O5 provide additional adsorption sites of CO2 producing more reactive unidentate CO2 adsorbed species. The presence of V2O5 also improved the dispersion and exposed more Ni species. This leads to an increased amount of reducible NiO species. Compared to 5Ni/KCC-1, the V2O5-Ni/KCC-1 series were active at lower temperature. The light off temperature for V2O5-Ni/KCC-1 was 423 K compared to 473 K for 5Ni/KCC-1. At 623 K, the 7.5V2O5-Ni/KCC-1 reaches 94.4% CO2 conversion, 15% higher than 5Ni/KCC-1. The presence of O2 negatively affects the catalytic activity as O2 interferes with the CO2 adsorption sites. The analysis of variance (ANOVA) indicates that the reaction temperature heavily influences the CH4 yield followed by the reduction temperature and H2 : CO2 ratio. The optimized conditions by the RSM are a reduction temperature of 696.9 K, a reaction temperature of 766.5 K and a H2 : CO2 ratio of 5.1.