Inhibition of water-gas shift reaction activity of oxide-supported Pt catalyst by H2 and CO2

Abstract

A catalyst composed of platinum-group metals supported on an oxide exhibits high activity in a low-temperature water-gas shift (LT-WGS) reaction; however, the reaction rate is greatly reduced when H2 or CO2, the product gases of the WGS reaction, are included in the reactant stream. In this study, we attempted to understand the origin of this activity inhibition by analyzing the kinetic data with in-situ CO-diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). The WGS reaction rate decreases more severely by H2 than CO2. The CO-DRIFTS spectra indicate that this can be explained by H2 preoccupying the active sites for the WGS reaction. In addition, by comparing the kinetic data with the literature, it could be inferred that a similar inhibition mechanism is operating in other oxide-supported Pt catalysts. Considering this inhibition mechanism will be important for the development of catalysts with high WGS activity in reformate gas.