Effect of Mg and Ca addition on coke deposition over Cu-Ni/SiO2 catalysts for ethanol steam reforming

The production of hydrogen from ethanol steam reforming with Cu-Ni catalysts supported on MgO- and CaO-modified silica has been studied. Two promoting effects have been found: reduction of the metallic Cu-Ni particles size and strengthening of the metal-support interaction. Moreover, Mg- and Ca-promoted catalysts favour the formation of defective carbon, which is more reactive and thermodynamically easier to be removed during the ethanol steam reforming process. Consequently, higher hydrogen production and lower coke formation are achieved when Cu-Ni catalysts are supported on Mg- or Ca-modified silica in comparison to unmodified Cu-Ni/SiO2 catalyst. The highest hydrogen selectivity (84.8 mol%) is reached with a Cu-Ni/Mg-SiO2 catalyst containing 10 wt% Mg, while the incorporation of 10 wt% Ca into Cu-Ni/SiO2 catalyst reduces considerably the amount of coke deposited from 58.4 to 26.3 wt%, after 3 h of time on stream. (C) 2010 Elsevier B.V. All rights reserved.