Enhancement in nickel-silica interface generation by surfactant-assisted melt-infiltration: Surfactant selection and application in CO₂ hydrogenation

Effective nickel-based catalysts used in CO₂ methanation require high loadings (∼40 wt%) of nanoscale (∼10 nm) nickel particles. However, particle loading and size are inversely proportional. Surfactant-assisted melt-infiltration (SAMI) may alleviate this problem. In this study, various solid surfactants (Span60, SDBS, and CTAB) were homogeneously mixed with nickel nitrate and mesoporous silica support (SBA-15) under non-solvent conditions during melt-infiltration. The non-ionic surfactant (Span60) afforded a high loading (40 wt%) of nanoscale (11 nm) nickel particles and generated a large number of interfaces between the nickel particles and the support. These interfaces may contain oxygen vacancies that facilitate the adsorption–dissociation of CO₂ on the catalyst surface. The Span60/40Ni/as-syn-SBA-15 catalyst exhibited the highest catalytic activity with CO₂ conversion of 78 % and CH₄ selectivity of 99 % at a temperature of 350 ℃ (Space Velocity: 120,000 mL/ g_cat·h). The nanoscale size of the catalyst improved the catalytic performance by ensuring a simple and efficient reaction pathway. The SAMI method generates no liquid waste and may be commercialized to produce efficient catalysts.