Role of Re in Pt-Re/TiO sub(2) catalyst for water gas shift reaction: A mechanistic and kinetic study

Transient kinetic studies and in situ FTIR spectroscopy were used to follow the reaction sequences that occur during water gas shift (WGS) reaction over Pt-Re/TiO sub(2) catalyst. Results pointed to contributions of an associative formate route with redox regeneration and two classical redox routes involving TiO sub(2) and ReO sub(x), respectively. Under WGS reaction condition rhenium is present at least partly as ReO sub(x) providing an additional redox route for WGS reaction in which ReO sub(x) is reduced by CO generating CO sub(2) and re-oxidized by H sub(2)O forming H sub(2). The overall reaction rate, based on steady state kinetics, was given by [View the MathML source], where beta is the approach to equilibrium. Results obtained in the study indicated that the reaction between CO adsorbed on Pt and OH groups on titania is the rate-determining step.