Oxygen Vacancy Induced Strong Metal-Support Interactions on Ni/Ce<sub>0.8</sub>Zr<sub>0.2</sub>O<sub>2</sub> Nanorod Catalysts for Promoting Steam Reforming of Toluene: Experimental and Computational Studies
Feng Lin, Zezhi Chen, Huijuan Gong, Xiaoshu Wang, Lu Chen, Huiqiang Yu
Abstract
To develop an efficient Ni-based steam reforming catalyst for tar removal from the products of biomass gasification, Ni/Ce 0.8 Zr 0.2 O 2 nanorods were designed. The Ni/Ce 0.8 Zr 0.2 O 2 nanorod was used as a catalyst in steam reforming of toluene, which was regarded as a model compound of biomass gasification tar. At gas hourly space velocity (GHSV) of 24,000 h –1 and Ni loading of 5 wt %, the 5Ni/Ce 0.8 Zr 0.2 O 2 nanorod catalyst achieved 100% of toluene conversion at 600 °C. After 10 h of operation, toluene conversion still reached 87.6%, and the carbon deposition rate was only 1.9 mg/g cat h –1 . The experimental results demonstrated that the 5Ni/Ce 0.8 Zr 0.2 O 2 nanorod catalyst showed much higher catalytic activity and coking resistance than other Ni-based catalysts reported in the literature. Through different characterization technologies and density functional theory calculations, it was confirmed that the excellent catalytic performance was attributed to the strong metal-support interaction (SMSI) between Ni and the {100} facet of Ce 0.8 Zr 0.2 O 2 . The special surface structure of {100} allowed Ni atoms to anchor to the surface oxygen vacancies and maintained its reduced state by electron transport between surface atoms. The anchored Ni facilitated oxygen vacancies formation and H 2 O dissociation on the support, while the support modulated the electronic structure of Ni, which promoted its ability to toluene activation.