Steam reforming of ethanol for production of hydrogen over Ni/CeO2-ZrO2 catalyst:: Effect of support and metal loading

Steam reforming (SR) of ethanol for hydrogen production was investigated over Ni/Ce1-xZrxO2 (x = 0, 0.26, 0.59, 0.84 and 1) catalyst prepared by co-precipitation and incipient wetness impregnation technique. The effect of support composition as well as metal loading on SR reaction was studied in a downflow tubular fixed bed reactor at atmospheric pressure with an ethanol/water molar ratio of 1:8, over a temperature range of 400 to 650 degrees C. The catalysts were characterized by various techniques, such as surface area, temperature-programmed reduction (TPR), X-ray diffraction (XRD) and H-2 chemisorption. The XRD results confirmed the formation of mixed oxide solution. TPR results revealed that, compared to pure oxide support, strong interaction exists between the mixed oxide support and metal. Among the catalyst examined, Ce0.41Zr0.59O2 and Ce0.16Zr0.84O2 supports were the least active and Ni/Ce0.74Zr0.26O2 catalyst with 30wt% metal loading exhibited high catalytic activity and hydrogen selectivity (5.8 mol/mol of ethanol reacted) at a temperature of 600 degrees C. At this temperature, the ethanol conversion was 100% and the selectivities of CO, CH4, CO2 were 0.47, 0.33, 1.15 mol/mol of ethanol reacted, respectively. For nickel supported on Ce0.74Zr0.26O2, the activity was found to correlate with the hydrogen consumed during TPR. Another reason for the high activity of 30 wt% Ni/Ce0.74Zr0.26O2 could be due to the high oxygen storage capacity of cubic Ce0.74Zr0.26O2. This helps to increase the availability of surface oxygen. (C) 2006 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.