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

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. (C) 2017 Elsevier Inc. All rights reserved.