Ni supported on CaO MgO Al2O3 as a highly selective and stable catalyst for H2 production via the glycerol steam reforming reaction
Abstract A comparative study of the GSR performance for Ni/CaO MgO Al2O3 and Ni/Al2O3 catalysts is reported. Catalysts were synthesized applying the wet impregnation method at a constant metal loading (8 wt Synthesized samples were characterized by N2 adsorption/desorption, ICP, BET, XRD, NH3 TPD, CO2 TPD, H2 TPR, XPS, TEM, STEM HAADF and EDS. The carbon deposited on their surface under reaction conditions was characterized by TPO, Raman and TEM. It was proven that the use of CaO MgO as alumina modifiers leads to smaller nickel species crystallite size, increased basicity and surface amount of Ni0 phase. Thus, it increases the conversion to gaseous products favoring H2 and CO2 production to the detriment of CO formation, by enhancing the water gas shift (WGS) reaction. No liquid products were produced by the Ni/modAl catalyst over 550 degC, whereas time on stream results confirmed that deactivation can be prevented, as apart from decreasing the amount of coke deposition the nature of carbon was altered towards less graphitic and more defective structures.