Mo-Based Catalyst Supported on Binary Ceria–Lanthanum Solid Solution for Sulfur-Resistant Methanation: Effect of La Dopant

A series of Mo-based catalysts supported on Ce1–xLaxO2−δ solid solution were prepared and performed in sulfur-resistant methanation. Characterization results suggested the formation of Ce1–xLaxO2−δ solid solution with a cubic fluorite structure. The correlation between the surface concentration of Ce3+ and oxygen mobility was well revealed. The higher oxygen storage capacity induced by La dopant enhanced the reducibility of the MoO3/Ce1–xLaxO2−δ during the sulfidation. Meanwhile, the presence of oxygen vacancy induced by Ce3+ prompted the sulfidation of Mo species, resulting in a higher dispersion of MoS2. The coupling between the CO hydrogenation and water–gas-shift (WGS) reaction is important for the sulfur-resistant methanation. The apparent methanation rate is easily determined by CO hydrogenation, and WGS reaction could provide more H2 for the CO hydrogenation. MoO3/Ce0.8La0.2O2−δ catalyst exhibited the highest activity in a broad temperature regime of 450–550 °C due to its high MoS2 dispersion and surface concentration of Ce3+.