Hydrogen production by ethanol reforming over Rh/CeO2-ZrO2 catalysts

Reforming of ethanol in excess of water (1-8 molar ratio) has been investigated on Rh/CeO2, Rh/ZrO2 and Rh/CeO2-ZrO2 (Ce/Zr = 4, 2 and 1). Catalysts characterization was conducted by X-ray diffraction, BET surface area measurements, CO2 adsorption, and temperature programmed reduction (TPR). At 400-500 degreesC all catalysts showed high activity and selectivity towards hydrogen production (between 5 and 5.7 mol of H-2 per mol of ethanol inlet) despite the considerable textural differences of the oxides (fluorite, monoclinic and tetragonal). The large variations of Rh dispersion (as monitored by TPR) between all catalysts had a small effect on H-2 production. Although it appears that the reaction is not sensitive to either the oxide or the metal structure Rh/CeO2 (the most basic catalyst investigated) was the least reactive. (C) 2002 Published by Elsevier Science B.V.