Embedding uniform Ni nanoparticles into silicalite-1 zeolite for dry reforming of methane

Abstract

Embedding Ni nanoparticles (NPs) into a catalyst support is a highly efficient way to make catalysts for the dry reforming of methane (DRM). However, large Ni particle sizes and their uneven distribution result in metal sintering and catalyst deactivation. Herein, using a nanosized MFI zeolite silicalite-1 (S-1) as the support, a Ni@S-1 zeolite catalyst with highly dispersed Ni NPs was synthesized by an ethanol-assisted impregnation method. Ni NPs with a small size (1.5 nm) are uniformly encapsulated in the S-1 zeolite, whereby they slightly increase to 2.5 nm in size after the DRM reaction but remain well dispersed. Compared with a Ni/S-1 catalyst prepared by the deposition–precipitation method, the sizes of the Ni NPs in the Ni@S-1 catalyst remain smaller and present a more uniform dispersion after reaction. The strong metal–support interactions between the encapsulated Ni species and S-1 zeolite endowed the Ni@S-1 catalyst with high sintering- and coking-resistant properties in the dry reforming of methane. The CH₄ and CO₂ conversions over Ni@S-1 catalyst can still reach 89% and 94% after 200 h, respectively, which are superior to most reported Ni-based zeolite catalysts and other Ni-based catalysts. This work provides guidance for the synthesis of high-performance Ni-based zeolite catalysts.