Selective steam reforming of n-dodecane over stable subnanometric NiPt clusters encapsulated in Silicalite-1 zeolite

Multimetallic nanocatalysts have attracted increasing attention for steam reforming owing to highly exposed active sites, but often suffering from severe sintering. Herein, we design subnanometric Ni-Pt bimetal clusters (ca. 1.7 nm) encapsulated in Silicalite-1 zeolite (2Ni0.5Pt@S-1) through ligand-stabilized method to prevent sintering by fixing the metal into microporous channels. In the steam reforming of n -dodecane test, 2Ni0.5Pt@S-1 gave an excellent activity and stability with a decrease of conversion only 4% at 600°C for 4 hr, which was about a quarter that of 2Ni0.5Pt/S-1 synthesized by co-impregnation method, ascribing to superior sinter-resistance of encapsulation structure. Moreover, 2Ni0.5Pt@S-1 exhibited a higher H 2 selectivity up to 69.9% than that of 2Ni0.5Pt/S-1 (64.4%), owing to suppressed methanation reaction based on subnanometric clusters. Shape-selective steam reforming of n -dodecane and ofm -xylene was also observed, because of m -xylene could hardly diffuse into the zeolite channels due to its bulky molecular size, further preventing potential deactivation by tars in reforming process.