Promotional Effects of Mg-Substituted Ni/Mg<sub><i>x</i></sub>HAP Catalysts on Carbon Resistance during Dry Reforming of Methane
Bo Gong, Tongming Su, Xinling Xie, Hongbing Ji, Zuzeng Qin
Abstract
Supported Ni-based catalysts were easily sintered and deactivated in the dry re-forming of methane (DRM), resulting from a weak metal–support interaction. To solve this problem, a series of Mg-substituted hydroxyapatite (HAP) catalysts (Ni/Mg x HAP, x = 0, 0.5, 1, 1.5) with 3% Ni loaded were prepared by partial substitution of Ca in HAP by Mg and used for DRM. The results showed that the presence of Mg influenced the formation and growth of HAP, resulting in lattice distortion and the formation of a large number of lattice defects in HAP, thus promoting Ni entry into the HAP lattice, and the amount of Ni 2+ [II] in the HAP lattice increased. Ni 2+ [II] in the lattice did not easily sinter at a high temperature, and the Ni average particle size of the Ni/Mg 1 HAP catalyst was the smallest (7.5 nm) after reduction at 700 °C; in addition, the specific surface area of the catalyst increased after Mg substitution. After a 100 h stability test, the Ni/Mg 1 HAP catalyst maintained high catalytic activity. In situ infrared studies showed that Ni/Mg 1 HAP inhibited the formation of monodentate carbonate and prevented deactivation of the catalyst caused by the coverage of active sites.