High temperature methanation over Ni catalysts supported on high surface area Zn_xMg_(1-x)Al_2O_4: Influence on Zn loading

摘要

A series of 10 wt % Ni based catalysts supported on ZnxMg1-xAl2O4 were prepared using a co-precipitation and impregnation method for high temperature syngas methanation. The effect of Zn loading on catalysts' textural property and catalytic performance was investigated by BET, XRD, TEM, H-2-TPR, XPS and CO-TPD analysis. It was found that a modest addition of Zn significantly increased the surface area of the catalysts, which moderated the strong interaction between NiO and the support. This effect enhanced the reduction of the Ni, thereby improving the dispersion of the active metal on the support and intensifying the adsorption of CO. In addition, surface Ni concentration was improved by the Zn substitution. Among the various catalysts tested, Ni/Zn0.7Mg0.3Al exhibited the best catalytic performance at 500 degrees C, 2.0 MPa and 30, 000 ml g(-1). min(-1), with a CO conversion, CO2 conversion and CH4 selectivity of 99.7, 53.1 and 98.7%, respectively. Furthermore, the Ni/Zn0.7Mg0.3Al catalysts also maintained excellent stability during a 120 h life test. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.