Highly stable mesoporous NiO-Y2O3-Al2O3 catalysts for CO2 reforming of methane: effect of Ni embedding and Y2O3 promotion

A series of mesoporous NiO-Y2O3-Al2O3 composite oxides with different yttrium contents were synthesized by either a one-pot evaporation-induced self-assembly (EISA) method or impregnation for carbon dioxide reforming of methane (CRM). Their catalytic performance was evaluated and all the samples were characterized by means of N-2 physisorption, XRD, XPS, H-2-TPR and TEM. It was found that addition of appropriate amounts of Y2O3 (sample NYA2) has little influence on the EISA process, and thus, an ordered mesoporous structure with enhanced textural and Ni dispersive properties can be obtained. The NYA(2) catalyst showed excellent performance in CRM, and no deactivation was observed for 100 h. Based on the comparative characterization of the reduced and exhausted catalysts, the good performance of NYA(2) was related to its low carbon formation rate thanks to the very small and thermally stable metallic Ni particles (ca. 6.0 nm) which were well embedded in the catalyst framework and the redox properties of the Y2O3 promoter.