Stabilized CO₂ reforming of CH₄ on modified Ni/Al₂O₃ catalysts via in-situ K₂CO₃-enabled dynamic coke elimination reaction

CO₂ dry reforming of methane (DRM) is one of the most promising routes for the large-scale utilization of greenhouse gases (CO₂ and CH₄). However, it is still of challenges to develop catalysts that are efficient and cheap but are of high resistivity in coke formation to maintain long-term stability. Herein, K₂CO₃ was used as a promoter to enable dynamic coke elimination reaction over the Ni/Al₂O₃ for CO₂ reforming of CH₄. K₂CO₃-modified Ni/Al₂O₃ catalysts were synthesized via a wet co-impregnation method and investigated for DRM. The 1.0 K-Ni/Al₂O₃ exhibited the best stability in the test of 96 h on stream at 800 °C. It was found that coke resistance of K₂CO₃ modified catalyst was significantly improved, as the coke formation on 1.0 K-Ni/Al₂O₃ catalyst was only 1/3 of that on Ni/Al₂O₃ catalyst after a long-term test. Characterization results showed that the growth of Ni particles was suppressed because the addition of K₂CO₃ enhanced the interaction between Ni and Al₂O₃. Meanwhile, the addition of K₂CO₃ raises the basicity of the catalysts, which enhances the adsorption of CO₂ on the surface and subsequently facilitates CO₂ dry reforming of CH₄. In addition, the transient experiment reveals that K₂CO₃ enables a dynamic coke elimination reaction (KCER) via enhancing the catalytic reaction of disordered carbon with CO₂, which is considered as a promising low-cost approach to stabilize the performance of the Ni-based catalysts in DRM reaction.