Highly efficient Ni/Ac–Al2O3 catalysts in the dry reforming of methane: influence of acetic acid treatment and Ni loading

Abstract

The presence of abundant hydroxyl groups on the surface of Al₂O₃ can promote the dispersion of Ni species but produce an inactive NiAl₂O₄ phase at high temperatures. Moreover, the catalysts prepared by the conventional incipient wetness impregnation method lack the sites for the activation of CO₂, which leads to coke deposition and thus affects the catalyst activity. The above restricts the utilization of Ni in conventional Ni/Al₂O₃ catalysts. In this paper, Al₂O₃ support was pre-treated by acetic acid to selectively remove hydroxyl groups without affecting the coordination environment of Al. Results revealed that the Al₂O₃ support after hydroxyl removal not only showed moderate metal–support interaction but also produced more sites for the adsorption and activation of the reactant, which significantly improves the utilization of nickel species and the stability of the catalyst. The conversion of CH₄ and CO₂ at 700 °C was as high as 88% and 90%, respectively, and has an excellent stability of 50 h. This study provides a feasible strategy for the design of highly active methane dry-reforming catalysts.