Single step solid-state fusion for MgAl2O4 spinel synthesis and its influence on the structural and textural properties

Abstract

Magnesium aluminate (MgAl2O4) spinel nanostructure has been synthesized using a single step solid-state fusion method, with citric acid as a surfactant. The samples prepared at different annealing conditions such as temperature and duration, were analyzed to study their effects on the structural, crystalline and textural properties of MgAl2O4 spinel, such as specific surface area, morphology, crystallite size and agglomeration. The prepared samples were characterized using X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) surface area analysis, Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). Increasing the annealing duration has insignificant influence on the crystallinity and the formation of spinel phase. However, with increasing annealing temperature, significant effects were observed, namely, decreasing specific surface area, increasing pore size and crystallite size, and increasing degree of agglomeration. Samples prepared at different annealing temperatures were then tested for catalytic methane steam reforming to understand their catalytic properties. It was found that the MgAl2O4 spinel with high surface area and small crystallite size showed good catalytic activity at 700 °C, with a steam to carbon ratio of 2.