Rare Earth (Gd, Pr and La) Promoted Three-Dimensional Ordered Macro/Mesoporous Ni/CeZr Catalysts for Low-Temperature Catalytic Steam Reforming of Toluene as Tar Model

Nickel (Ni)-based catalyst is widely adopted for tar removing in the process of biomass gasification. In order to improve low-temperature catalytic activity of Ni-based catalyst, three-dimensional ordered macro/mesoporous (3DOM/m) Ce 0.8 Zr 0.1 M 0.1 (M = Gd, Pr and La) ternary solid solutions were prepared and used as the carriers of Ni/Ce 0.8 Zr 0.1 M 0.1 catalysts. The obtained catalysts were employed to catalyze the steam reforming of toluene (SRT). The results demonstrated that all the Ni/Ce 0.8 Zr 0.1 M 0.1 showed excellent low-temperature catalytic activity and presented higher toluene conversion than Ni/Ce 0.8 Zr 0.2 . Among the catalysts, Ni/Ce 0.8 Zr 0.1 Pr 0.1 exhibited the highest toluene conversion, reaching 96.1% at 550 ℃ (toluene = 185 μmol min −1 , S/C = 3). The characterization results of catalysts showed that all the catalysts presented ordered three-dimensional morphology containing interconnected periodic macropores with abundant mesopores existing on the wall. The rare earth dopants were incorporated into the lattice of cerium-zirconium solid solution. As a result, the thermal stability of the carrier was improved, which made the BET specific surface area of the carrier increase and the dispersion of active component of Ni increase. Moreover, the incorporation of dopants produced more oxygen vacancies, thus improved reactive oxygen mobility. These superior properties of 3DOM/m Ce 0.8 Zr 0.1 M 0.1 led to their excellent catalytic activity in SRT. Graphical Abstract