Design of a carbon-resistant Ni@S-2 reforming catalyst: Controllable Ni nanoparticles sandwiched in a peasecod-like structure

Abstract

Ni-based catalysts for dry reforming of methane (DRM) suffer from the issue of carbon deposition and sintering. In this study, ultrafine nickel nanoparticles (NPs) embedded in the microporous silicalite-2 (S-2) with a peasecod-like structure was prepared by a facile one-pot approach. The size of Ni NPs (ca. 2, 4, 6 and 8 nm) can be precisely controlled by the degree of Ni-O-Si copolymerization. The obtained Ni@S-2 catalyst with Ni NPs size of 2.6 nm exhibited superior activity and stability with no carbon deposition under 650 °C, CH4:CO2 = 1:1 for 50 h. The layered walls of micropores of S-2 posted steric physical barriers against the migration of Ni NPs. Meanwhile, the strong interaction between active Ni and substrate (Ni-O-Si) provided chemical confinement for anti-sintering. This dual physical-chemical confinement strategy to synthesize catalyst with active Ni° sandwiched between layers of tetrahedral SiO4 provides a promising technique for designing other stable metal nanocomposites.