Hydrogen production by ethanol steam reforming over M-Ni/sepiolite (M = La, Mg or Ca) catalysts

Abstract

Ethanol steam reforming (ESR) is a technology of great promise for hydrogen production but designing highly efficient, green and inexpensive Ni-based catalysts for inhibiting metal sinter and carbon deposition and increasing catalyst activity and stability is still a key challenge. In this paper, the M-Ni/Sepiolite catalysts (M-Ni/SEP, M = La, Mg or Ca) were synthesized using a hydrothermal-assisted impregnation method. The results from characterizations such as N2 adsorption-desorption, XRD, H2-TPR, XPS, HRTEM and NH3/CO2-TPD showed that La, Mg and Ca promoters can facilitate the dispersion and exposure of Ni0 active sites, enhance the metal-support interaction and modify surface acid/alkaline sites. Furthermore, the results of catalyst activity tests in ESR demonstrated that the Ca–Ni/SEP catalyst exhibited the highest carbon conversion of 95% and hydrogen yield of 65%, attributed to the small mean Ni particle size, strong metal-support interaction, abundant surface Ni0 active sites and modified surface alkaline/acid sites. According to the carbon deposition analyses, it was observed in Ca–Ni/SEP that the carbon deposition amount was evidently decreased, and the graphitic degree of coke was increased due to the increased metal site amount.