Abstract
The low temperature water gas shift reaction has been studied over carbon- supported platinum catalysts promoted by ceria. To this end, CeO2 has been dispersed over an activated carbon support at different loadings (20, 30 and 40 wt.%) in order to obtain a high ceria surface area. Then, platinum has been incorporated by impregnation with an acetone solution of [Pt(NH3)(4)](NO3)(2). Two more catalysts have been prepared with aqueous and ethanolic solutions, respectively, to assess the effect of the solvent in the final catalysts. Pt/CeO2 and Pt/C catalysts have been used as references. Catalysts have been characterized (N2 adsorption at 77 K, TEM, H2-TPR) and tested in reaction after reduction with H2 at 473 K. The obtained results show that CO conversion increases with the amount of ceria loaded, from 20 to 40 wt.%. At this temperature, platinum supported on bulk CeO2 is less active than its carbon- based counterparts. The best results are obtained for the catalysts with 40 wt.% CeO2 prepared by aqueous impregnation of the platinum precursor, which achieves conversions higher than 70% at 573 K, and shows no deactivation under reaction at this temperature for 120 h. On the other hand, Pt/C shows a very low activity, this certifying the determinant role of ceria in this reaction. These results indicate that dispersion of ceria on activated carbon allows to obtain catalysts with superior performance than using bulk CeO2 as support, and with a lesser amount of ceria. (C) 2011 Elsevier B.V. All rights reserved.