Effect of Mg modification on the catalytic performance of Co/γ-Al2O3-TiO2 in the combustion of propane

Abstract

A series of Mg-modified Co/MgO/γ-Al2O3-TiO2 catalysts were prepared by multi-step impregnation method and characterized by X-ray diffraction (XRD), diffuse reflectance visible ultra violet spectroscopy (DR-UV-vis), N2 adsorption-desorption, X-ray photoelectron spectroscopy (XPS) and H2 temperature-programmed reduction (H2-TPR); the effect of Mg modification on the catalytic performance of Co/MgO/γ-Al2O3-TiO2 in the combustion of propane was investigated. The results indicate that Co exists in the form of Co3O4 on both the pristine γ-Al2O3-TiO2 and Mg-modified MgO/γ-Al2O3-TiO2 supports; Mg added in the MgO/γ-Al2O3-TiO2 support interacts with Al2O3, forming MgAl2O4 spinel, which can improve the textural properties and promote the dispersion of Co3O4. Moreover, the interaction between MgAl2O4 and Co3O4 can increase the proportions of Co3+/Co2+ and Oads/Olatt on the catalyst surface, weaken the Co–O bond, and thereby enhance the activity of Co-based catalyst in propane combustion. For the propane combustion over the Co/MgO(15%)/γ-Al2O3-TiO2 catalyst with an Mg loading of 15%, the temperature to achieve a propane conversion of 90% is decreased by 45°C in comparison with that over the Mg-free Co/γ-Al2O3-TiO2 catalyst; moreover, the Co/MgO(15%)/γ-Al2O3-TiO2 catalyst exhibits excellent stability and no decrease in the activity is observed in a 40 h continuous reaction test for propane combustion.