Weakening the metal-support strong interaction to enhance catalytic performances of alumina supported Ni-based catalysts for producing hydrogen

Abstract

Praseodymium (Pr) promoted Ni/Al2O3 catalysts with multiple Pr6O11 stabilized Ni0/NiO structure are synthesized by varying amounts of Pr and Ni using co-incipient wetness impregnation method and are investigated for hydrogen production via methanol steam reforming. Various technique, such as, XRD, H2-TPR, in-situ XPS, HRTEM and Raman, are used to characterize those materials. Characterization results show that Pr species is presented in the form of Pr oxide after reduction, and the geometrical and electronic action of Pr oxide on NiO species leads to the formation of multiple Pr6O11 stabilized Ni0/NiO structure, which promotes the low-temperature catalytic performance. Compared with Ni/Al2O3, 10 wt.% Pr promoted Ni catalyst exhibits the longer-term stability owing to the strong inhibition to the aggregation of metallic Ni0 particles, originating from the synergistic effect of Pr oxide on immobilization the metallic Ni0 particle and its size distribution as well as on the electronic role of Ni0/NiO species.