CO₂ hydrogenation over Co/SBA-15 and Co/SBA-16 catalysts promoted with Ceria

Abstract

In this study, the Co/SBA-15 and Co/SBA-16 having 20 wt% of cobalt were prepared by the conventional impregnation method. Then, the post-impregnation treatment such as vacuum and ultrasound treatments were applied. Moreover, Ce-promoted cobalt catalysts were also prepared by co-impregnation and sequential impregnation method. The catalyst samples were characterized by means of N2 physisorption, small angle X-ray diffraction (SAXRD), wide angle X-ray diffraction (XRD), scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM/EDX), transmission electron spectroscopy (TEM), and temperature-programmed reduction (TPR). It was found that the vacuum and ultrasound treatments can apparently enhance the dispersion of Co/SBA-15 catalysts, whereas only vacuum treatment was suitable for Co/SBA-16. After reduction, no cobalt-silicate compound was detected based on XRD measurement. Both post-impregnation treatments can also decrease the metal-support interaction resulting in increased activity for CO2 hydrogenation under methanation. Furthermore, addition of ceria was found to increase cobalt reducibility and decrease the metal-support interaction. This led to improve the catalytic performance. By the way, the combination of ceria addition with the post-impregnation treatment did not serve the best catalytic performance. Either ceria promotion or the post-impregnation treatment is indeed.