Low temperature catalytic steam reforming of ethanol. 1. The effect of the support on the activity and stability of Pt catalysts

The effects of the support (alumina or ceria) on the activity, selectivity and stability of 1 wt% Pt catalyst for the low temperature ethanol steam reforming reaction have been investigated. Experimental results in the range 300-450 degrees C showed a better performance of ceria supported catalyst, especially with reference to deactivation rate. The characterizations of catalysts reveal the presence of very well dispersed PtOx in the ceria that, during the calcination step, is stabilized in the highest oxidation state, in contrast with Al2O3. Moreover, H-2 TPR, and TPD showed that the better performances of the ceria supported catalyst are strictly linked to the greater ability of CeO2 to release and store oxygen, resulting in higher stability with respect to alumina supported catalysts. Coke formation, investigated by TPO experiments, occurred on supports and catalysts. However, more stable carbonaceous species were found on Al2O3 and Pt/Al2O3, likely responsible for the higher deactivation rate with respect to CeO2 supported Pt catalyst. Finally, catalytic activity, selectivity and stability of Pt/CeO2 catalyst increase by increasing the Pt load in the range 1-5 wt%. The best catalyst formulation (5 wt% Pt on CeO2) was selected for further studies. It is worthwhile that this catalyst is also active for the water gas shift conversion of CO to CO2, resulting in the absence of CO in the reformate product. (c) 2010 Elsevier B.V. All rights reserved.