Mechanochemical Synthesis of Ni–Y/CeO₂ Catalyst for Nonthermal Plasma Catalytic CO₂ Methanation

Nonthermal plasma (NTP)-assisted CO₂ methanation can activate and convert stable CO₂ molecules under ambient conditions as compared to conventional thermal catalysis (normal operation temperature up to 450 °C), which is a good technique to reduce CO₂ emissions and simultaneously utilize the renewable energies like solar and wind. It is critical to develop a robust catalyst with good catalytic performance in order to make NTP catalytic CO₂ methanation more competitive. Herein, we present a simple yet efficient synthesis of CeO₂-supported Ni catalysts with yttrium (Y) as the promoter (i.e., Ni–Y/CeO₂) via mechanochemical synthesis for efficient NTP catalytic CO₂ methanation. The developed 7.5Ni–1Y/CeO₂ catalyst demonstrated the highest energy efficiency values for CO₂ conversion and CH₄ yield, i.e., ∼57 g_CO2 kWh^–1 and ∼17 g_CH4 kWh^–1, respectively. The CO₂-TPD and HRTEM results confirmed that the doped Y positively enhanced the basicity of the catalysts and also decreased the particle size of Ni nanoparticles, thus promoting the NTP catalytic activity of CO₂ methanation. The catalyst displayed excellent short-term stability for plasma catalytic CO₂ methanation over a 12 h on-stream evaluation, showing a CO₂ conversion of 84.2 ± 1.8% and a CH₄ selectivity of 83.3 ± 1.9%.