Rational design of silica nanoreactor encapsulated Ni for reinforcing coke-resistance in dry reforming of methane

Abstract

Dry reforming of methane (DRM) provides a desired approach to produce valuable syngas in tackling greenhouse gases. Yet it faces a formidable challenge in the design and synthesis of high coke-resistant Ni-based catalysts. Herein, we report a nanoreactor strategy to construct a supported Ni catalyst (Ni@SiO2@SiO2) for reinforcing coke-resistance during DRM, by effectively encapsulating small Ni nanoparticles into dendritic fibrous silica (SiO2) nanospheres and coating SiO2 shell layers. Taking advantage of chemical characteristics of citric acid (CA), CA-chelated Ni impregnation enables the uniform immobilization of Ni species into the radial SiO2 framework, then following carbonization produces protective carbon layers on the Ni nanoparticle surface during SiO2 coating, which can be removed via oxidizing calcination. The resultant pomegranate-like nanoreactor catalyst possesses outstanding coke-resistance, without any detectable coke deposition after 200 h of DRM reaction at 700 ℃, benefiting from effectively restricting metal sintering and fully preventing formation of inert carbon species.