Enhanced stability of Ni/SiO2 catalyst for CO2 methanation: Derived from nickel phyllosilicate with strong metal-support interactions

Highlights: • A facile synthesis of Ni/SiO₂ catalyst by ammonia-evaporation method was reported. • The nickel loading was up to about 25.73 wt% with high dispersion in silica. • The Ni/SiO₂-AEM catalyst exhibited long-term stability for CO₂ methanation. • The nickel phyllosilicate played important roles in the catalyst's performance. -- Abstract: Nowadays more and more significant technologies have been developing to save energy and reduce emissions. CO₂ methanation has been an attractive process to reduce CO₂-emissions since it consumes CO₂ with H₂ derived from renewable energy sources to produce CH₄. However, the poor stability of Ni-based catalyst for CO₂ methanation is still challenging. Herein, two Ni/SiO₂ catalysts with different structure and catalytic properties were prepared by different methods. The Ni/SiO₂-AEM nanocatalyst with a lamellar structure of nickel phyllosilicate was synthesized by a facile ammonia-evaporation method (AEM), which can conveniently and uniformly disperse nickel species on SiO₂. Upon reduction of nickel phyllosilicate, it can disperse and confine small sized Ni particles (4.2 nm) in the silica support with a high surface area of 446.3 m²/g, leading to the Ni/SiO₂-AEM catalyst achieving a high yield of methane with long-term stability of 100 h under the GHSV of 10,000 mL/(g_cat h) and another 60 h with the GHSV increased to 30,000 mL/(g_cat h) at 370 °C. In comparison, the Ni/SiO₂-IM catalyst prepared by the impregnation method obtained lower yield of methane and worse stability under identical conditions. The results indicate that the catalyst with high surface area and strong metal-support interactions can improve stability.