Ni Nanoparticles Supported on Cage-Type Mesoporous Silica for CO₂ Hydrogenation with High CH₄ Selectivity

Ni nanoparticles (around 4 nm diameter) were successfully supported on cage-type mesoporous silica SBA-16 (denoted as Ni@SBA-16) via wet impregnation at pH 9, followed by the calcination-reduction process. The Ni@SBA-16 catalyst with a very high Ni loading amount (22.9 wt %) exhibited exceptionally high CH₄ selectivity for CO₂ hydrogenation. At a nearly identical loading amount, the Ni@SBA-16 catalysts with smaller particle size of Ni NPs surprisingly exhibited a higher catalytic activity of CO₂ hydrogenation and also led to a higher selectivity on CH₄ formation than the Ni@SiO₂ catalysts. This enhanced activity of the Ni@SBA-16 catalyst is suggested to be an accumulative result of the advantageous structural properties of the support SBA-16 and the well confined Ni NPs within the support; both induced a favorable reaction pathway for high selectivity of CH₄ in CO₂ hydrogenation.