Design an in-situ reduction of Ni/C–SiO₂ catalyst and new insights into pretreatment effect for CH₄–CO₂ reforming reaction

A series of Ni/C–SiO₂ catalysts with high Ni⁰ dispersion were prepared through impregnation method with glucose as the carbon source as well as the reduction agent. During the calcination process under N₂ atmosphere, the generated reductive substances, like CO, H₂ and carbon derived from decomposition and carbonization of glucose, which could transform NiO into Ni⁰ particles completely, according to XRD and H₂-TPR analysis. To improve the catalytic performance of CH₄–CO₂ reforming reaction, the Ni/C–SiO₂ catalyst was further pretreated under N₂, H₂ and CO₂ atmosphere prior to the reaction. The CO₂ pretreated catalyst exhibited excellent catalytic activity and superior stability comparing with other catalysts. A rapid deactivation occurred on the Ni/SiO₂ catalyst prepared by traditional impregnation method during 10 h test. Reversely, the CO₂ pretreated catalyst maintained a high CH₄, CO₂ and C_total conversion (71.1, 81.1 and 77.1%, respectively) during a 40 h time-on-stream test, which was attributed to homogenous Ni particles dispersion and strong interaction between metal and support. This methodology opens up a possibility for diversification in carbon-silica composite catalysts. The working catalyst without further reduction process will give the required metal-support interaction for the novel synthesis.