Methane dry reforming with carbon dioxide via Ni-based bimodal porecatalyst

摘要

The dry reforming of methane (DRM) with CO2 has been widely studied due to its important applications in producing of syngas (CO + H2), removal of two greenhouse gases, and upgrading of biogas (mainly composed of Chhand CO2) into value added chemicals. Compared to the noble metal catalysts, the nickel-based catalyst is suitable for industrial scaled-up DRM due to its high activity and low cost. However, nickel-based catalysts have been encountering a significant challenge that is the active metal sintering and coke deposition, leading to the catalyst deactivation and then the poor stability. Nevertheless, it has been reported that the deactivation of nickel catalysts can be suppressed by adding promoters like strong Lewis bases with the enhancementof chemisorb CO2, and like lanthanide elements with the capacity of oxygen storage and release. Aluminum oxide is a commonly applied catalyst carrier own to its good pore size dispersion, high specific surface area and high mechanic strength. Herein, wereport that the bimodal NiCeMgAI catalysts with different NiO-loading were synthesized by the refluxed co-precipitation method and were evaluated for DRM catalytic performance. The sample containing 15wt% NiO-loading (NiisCeMgAI) was found to be active enough at 750 °C with a high CH4 conversion of 96.5%. NiisCeMgAI catalyst kept its bimodal porosity after reduction and DRM reaction. The evolution of the NiisCeMgAI catalyst before and after the DRM reaction was investigated by BET, XRD, TEM, and TGA techniques. A schema of the DRM reaction on the bimodal NiisCeMgAI catalyst was proposed, and the correlation between the structure evolution and catalytic performance change was also discussed.