Enhancing Coke Resistance of Mg1-xNixAl2O4 Catalysts for Dry Reforming of Methane via a Doping-Segregation Strategy

Dry reforming of methane (DRM) is an important reaction to utilize two greenhouse gases (CO2 and CH4) simultaneously and produce syngas (CO and H-2) for the manufacture of downstream high-value chemicals. One of the major obstacles to preventing the commercialization of Ni-based catalysts in DRM is the serious coking problem. This work develops a doping-segregation method to manipulate the active metal structure and metal-support interaction of Mg1-xNixAl2O4 catalysts to enhance their coke resistance for DRM. The Mg1-xNixAl2O4 catalysts prepared via the sol-gel method exhibit outstanding coke resistance: the coke deposition rate of supported catalyst Ni/MgAl2O4 is 326 times higher than that of the Mg0.7Ni0.3Al2O4 catalyst at 600 degrees C. The Ni structure and metal-support interaction of Mg1-xNixAl2O4 catalysts have been systematically studied using various characterization. Combined with the temperature-programmed surface reaction (TPSR) experiments, the enhanced coke resistance of Mg1-xNixAl2O4 catalysts is attributed to smaller Ni particles, higher Ni dispersion, and stronger metal-support interaction, which significantly inhibit the direct dissociation of CH4 and promote the oxidation of formed coke. The findings of this work provide insights into the correlation between the enhanced coke resistance and the Ni structure of Mg1-xNixAl2O4 catalysts synthesized via the doping-segregation strategy using spinel as the precursor, leading to a stable catalyst design for many dry reforming reactions.