Promotional effect of samarium on the activity and stability of Ni-SBA-15 catalysts in dry reforming of methane

Abstract

Samarium-promoted of 10 wt% Ni-SBA-15 catalysts, were prepared with various loadings of samarium (0.5, 1.5, 3 wt %), by two-solvent impregnation, which was known as a desired metal dispersion method for dry reforming of methane. The catalysts with/without promoter, were characterized by N2 adsorption-desorption, x-ray diffraction (low and high angles of XRD), x-ray fluorescence (XRF), high resolution transmission electron microscopy (HRTEM), field-emission scanning electron microscopy (FESEM), energy dispersive x-ray spectrometry (EDS), wavelength dispersive x-ray spectrometry (WDS), temperature programmed oxidation/reduction (TPO/TPR) techniques, and tested in dry reforming of methane (DRM). XRD and BET results indicated that by adding more than 0.5%wt of samarium, decreased the catalysts' surface area and particles size; and improved the activity and long term stability. Among these promoted catalysts, 3Sm-10Ni-SBA-15 showed the highest catalytic activity and stability. TEM and TPR analysis of 3Sm-10Ni-SBA-15 sample, revealed that addition of samarium enhanced the interaction of NiO particles with support, and promoted dispersion of NiO species. The TPO analysis revealed that the addition of 3 wt% samarium increased the amount of deposited coke, as well. Furthermore, FESEM and HRTEM images confirmed the formation of nanotubes carbon on the surface of spent catalysts.