Preparation of La 2NiO 4/ZSM-5 catalyst and catalytic performance in CO 2/CH 4 reforming to syngas

Abstract

A La 2NiO 4/ZSM-5 catalyst was prepared by the sol–gel method, which ensured high dispersion of the metal and high activity in the CO 2 reforming of methane. The catalytic performance, catalyst stability and coke deposition as well as the influence of the doped La species on the Ni/ZSM-5 catalyst were investigated. The results show that the conversion of CO 2 and CH 4 to syngas and the selectivity of CO and H 2 observed over the La 2NiO 4/ZSM-5 catalyst were significantly higher than those over a Ni/ZSM-5 or La 2NiO 4/γ-Al 2O 3 catalyst. Such results suggest that the doping of the rare earth ion (La 3+) in the ZSM-5 not only enhanced the stability of the catalyst, but also increased the catalytic activity. In addition, the catalysts were characterized by X-ray diffraction (XRD), BET and thermogravimetic and differential thermal analysis (TG/DTA). The X-ray diffraction (XRD) studies revealed that the prepared catalyst, La 2NiO 4, exhibited a typical spinel structure and was uniformly dispersed both on the surface and in the ZSM-5 zeolite channels. During the CO 2/CH 4 reforming, the La 2O 3 generated from the La 2NiO 4 decomposition was transformed into La 2O 2CO 3 in an atmosphere of CO 2, which promoted CO 2 adsorption on the surface of the catalyst. The TG/DTA results indicate that the amount of carbon deposition on the La 2NiO 4/ZSM-5 catalyst was smaller than the amount on the Ni/ZSM-5 catalyst, and that there were at least two kinds of carbon deposition on the used La 2NiO 4/ZSM-5 catalyst. However, only one kind of carbon deposition existed on the used Ni/ZSM-5 catalyst.