Effect of the nature of the support on the catalytic performance of noble metal catalysts for the water–gas shift reaction

Abstract

The catalytic activity of supported noble metal catalysts (Pt, Rh, Ru, and Pd) for the WGS reaction is investigated with respect to the physichochemical properties of the metallic phase and the support. It has been found that, for all metal-support combinations investigated, Pt is much more active than Pd, while Rh and Ru exhibit intermediate activity. The turnover frequency (TOF) of CO conversion does not depend on metal loading, dispersion or crystallite size, but depends strongly on the nature of the metal oxide carrier. In particular, catalytic activity of Pt and Ru catalysts, is 1-2 orders of magnitude higher when supported on “reducible” (TiO 2, CeO 2, La 2O 3, and YSZ) rather than on “irreducible” (Al 2O 3, MgO, and SiO 2) metal oxides. In contrast to what has been found in our previous study over Pt/TiO 2 catalysts, catalytic activity of dispersed Pt does not depend on the structural and morphological characteristics of CeO 2, such as specific surface area or primary crystallite size.