Alumina supported Ni and Co catalysts modified by Y2O3 via different impregnation strategies: Comparative analysis on structural properties and catalytic performance in methane reforming with CO2

• Impregnation strategy of Y2O3 addition on Ni/Al2O3 and Co/Al2O3 catalysts.
• Positive effect of Y2O3 on Ni/Al2O3 and negative effect of Y2O3 on Co/Al2O3.
• Ni/YAl2O3 exhibited better activity and stability compared to Ni + Y/Al2O3.
• Co/YAl2O3 showed the largest amount of carbon deposit and metal sintering.

The overall purpose of this study was to develop an effective catalyst with high carbon resistance in the conversion of methane to synthesis gas via dry reforming. The catalytic performances of α-Al2O3 supported nickel- and cobalt-based catalysts modified with Y2O3 were investigated in this process. Sequential impregnation and co-impregnation of Y2O3 addition were employed during the catalyst preparation. The modification effect of Y2O3 and the preparation strategies on the surface structure, physico-chemical properties and coke deposition were revealed. For nickel catalysts, two impregnation methods of yttrium addition both greatly increased the activity and stability compared with counterpart Ni catalyst. Furthermore, the best performance over Ni/YAl2O3 catalyst prepared by sequential impregnation was related to smaller metallic nickel particle and more basic sites, while its remarkable stability was due to the small degree of graphitization and the less amount of carbon deposit. This sintering-resistant and higher carbon-resistant nickel catalyst is potentially useful for methane conversion in high reaction temperature. On the contrary, the negative effect of Y2O3 was clearly found for Co/Al2O3 catalyst. The introduction of Y2O3 led to inadequate reduction and metal sintering in reduced and spent catalysts. Co/YAl2O3 prepared by sequential impregnation exhibited steep deactivation during the methane reforming reaction because of the obvious cobalt sintering and serious carbon deposition.