A highly active Ni catalyst supported on Mg-substituted LaAlO3 for carbon dioxide reforming of methane

Abstract

The pristine and Mg-substituted LaAlO3 perovskites were synthesized by the citrate sol-gel method and employed as supports for Ni catalysts in CO2 reforming of methane. The Mg/La molar ratio of 2/8 was determined as the optimal amount of Mg substitution in Ni/La1-xMgxAlO3-δ catalysts. Compared with the Ni/LaAlO3 catalyst, the Ni/La0.8Mg0.2AlO2.9 catalyst exhibited enhanced initial activity and improved stability. Structural characterizations including N2 sorption (N2 sorption), X-ray diffraction (XRD), transmission electron microscopy (TEM), energy-dispersive X-ray spectrometry (EDX) elemental mapping, thermogravimetry-differential scanning calorimetry (TG-DSC), CO2 temperature-programmed desorption (CO2-TPD), X-ray photoelectron spectroscopy (XPS) and H2 temperature-programmed reduction (H2-TPR) were performed to elucidate the effect of Mg partial substitution. It is revealed that much smaller Ni nanoparticles were formed with Mg partial substitution, which may explain the enhanced reforming activity. The improved stability over the Ni/La0.8Mg0.2AlO2.9 catalyst was rationalized with better anti-coke and anti-sintering properties, which was closely related with surface basicity, oxygen vacancies and metal-support interactions. The present work demonstrates that perovskites with appropriate surface modification can serve as novel supports for the preparation of highly active catalysts.