Novel synthesis of high surface area MgAl 2O 4 spinel as catalyst support

Abstract

A modified sol–gel route, by combining gelation and coprecipitation processes, was developed for the synthesis of high surface area MgAl 2O 4 spinel precursors. The obtained precursors were then calcined in flowing air at temperatures ranging from 500 to 900 °C. The formation of new phases upon calcinations was investigated using X-ray diffraction, thermal gravimetric analysis, and Fourier transform infrared spectroscopy (FTIR). Single-phase spinel powder with uniform pore size distribution was formed at temperatures as low as 600 °C. It was found that the thermal stability of the as-synthesized spinels is higher than that reported by other preparation methods. After calcinations at 800 and 950 °C for 8 h, the specific surface area reaches a level of 182 and 136 m 2·g −1, respectively. And the degree of crystallinity is higher than other preparation methods as illustrated by samples calcined at 800 °C. The amount of PVA added significantly affects the surface area of the samples. With increasing the ratio of M/PVA, the surface area of the resulting spinels increased accordingly.