Synthesis of high surface area MgAl2O4 spinel as catalyst support via layered double hydroxides-containing precursor

Abstract

Magnesium aluminate spinel (MgAl2O4) was synthesized via layered double hydroxides (LDHs)-containing precursor by co-precipitation method. The precursors and the calcined powders were characterized by various techniques including N2 physical adsorption, powder X-ray diffraction (XRD), 27Al nuclear magnetic resonance (NMR), thermogravimetric and differential thermal analysis (TG-DTA), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The characterization results suggested that the as-synthesized precursor was mainly composed of MgAl LDHs and gibbsite Al(OH)3. Upon calcination of the LDHs-containing precursor at 600~700°C, MgAl2O4 spinel was formed and a high BET specific surface area of ~193m2g−1 was achieved at 700°C, demonstrating the effectiveness of LDHs-containing precursor for the preparation of high surface area MgAl2O4 spinel. It was suggested that the poorly crystalline Mg(Al)O solid solution resulted from the thermal decomposition of MgAl LDHs might facilitate the formation of MgAl2O4 spinel. The precipitation procedure had significant effect on the textural property of spinel. The MgAl2O4 prepared by constant pH precipitation exhibited much higher BET specific surface area than those prepared by decreasing pH precipitation and increasing pH precipitation. This high-surface area MgAl2O4 appeared a promising catalyst support. The prepared MgAl2O4-supported Ni catalyst possessed well-dispersed Ni nanoparticles and exhibited stable activity for the carbon dioxide reforming of methane.