Preparation of La2NiO4/ZSM-5 catalyst and catalytic performance in CO2/CH4 reforming to syngas

A La2NiO4/ZSM-5 catalyst was prepared by the sol-gel method, which ensured high dispersion of the metal and high activity in the CO2 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 CO2 and CH4 to syngas and the selectivity of CO and H2 observed over the La2NiO4/ZSM-5 catalyst were significantly higher than those over a Ni/ZSM-5 or La2NiO4/gamma-Al2O3 catalyst. Such results suggest that the doping of the rare earth ion (La3+) 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, La2NiO4, exhibited a typical spinel structure and was uniformly dispersed both on the surface and in the ZSM-5 zeolite channels. During the CO2/CH4 reforming, the La2O3 generated from the La2NiO4 decomposition was transformed into La2O2CO3 in an atmosphere of CO2, which promoted CO2 adsorption on the surface of the catalyst. The TG/DTA results indicate that the amount of carbon deposition on the La2NiO4/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 La2NiO4/ZSM-5 catalyst. However, only one kind of carbon deposition existed on the used Ni/ZSM-5 catalyst.