Silicalite-Supported Ni Catalysts for Efficient CO2 Conversion into CH4

The catalytic conversion of CO2 into methane (CH4) offers a sustainable solution to the worsening global warming scenario, especially for controlling CO2 levels. This study reports silicalite-1 supported Ni catalysts with different loadings for CO2 conversion to CH4, prepared via wet impregnation. The X-ray diffraction pattern revealed an increase in crystallite size at higher Ni loadings, which was further supported by N2 sorption, where the specific surface area and microporosity of the catalysts were decreased. There was a slight shift in the reducibility of the catalysts, potentially indicating the impact of loading on dispersion and spatial distribution. The catalyst performance was evaluated over a range of temperatures at 5 bar and a GHSV of 20,000 mL gcat−1 h−1. Surprisingly, the Ni(5)@Silicalite-1 exhibited higher CO2 conversion efficiency across the range of temperatures compared to Ni(10)@Silicalite-1. The NiO(5)@Silicalite-1 demonstrated a maximum CO2 conversion of 88% at 450 °C, which was approximately 14% higher than that of the catalyst with a 10 wt.% loading. Notably, the CH4 selectivity pattern was quite identical across the catalysts, underscoring that the reaction pathways were unaffected by the loadings. The higher performance of NiO(5)@Silicalite-1 could be ascribed to smaller NiO crystallites and improved textural properties.