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.