VOx-Pt/Al2O3 catalysts for hydrogen production

Platinum supported catalysts are promising systems to a wide range of catalytic reactions involved in the hydrogen production chain. The performance of these catalysts can be enhanced by designing properly their nature, composition and structure. In this context, the addition of a second metal oxide on a catalyst composed of a well dispersed Pt phase over a high surface area support may be a powerful strategy. In this work we impregnated VOx species over Pt/Al2O3 and evaluated the catalysts performance for water -gas shift (WGS) and glycerol steam reforming (GSR) reactions. The catalysts characterization showed that VOx species formed over the Pt/Al2O3 surface were not deeply affected by the loading in the range of 0.5-2.0 V atoms per nm(2) and were reduced at mild temperatures. In situ measurements during catalysts activation and WGS reaction showed that VOx species presented mixed valence (V3+/V4+) while Pt was in metallic state. The addition of vanadium increased Pt/Al2O3 WGS activity; however, the improvement did not linearly correlate with the loading. Under GSR, the results indicated that the WGS step was favored by the presence of vanadium but the selectivity to H-2 decreased, which could be attributed to the parallel reactions enhanced by the acidic nature of the VOx sites. (C) 2016 Elsevier B.V. All rights reserved.