Role of Re in Pt-Re/TiO2 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/TiO2 catalyst. Results pointed to contributions of an associative formate route with redox regeneration and two classical redox routes involving TiO2 and ReOx, respectively. Under WGS reaction condition rhenium is present at least partly as ReOx providing an additional redox route for WGS reaction in which ReOx is reduced by CO generating CO2 and re-oxidized by H2O forming H2. The overall reaction rate, based on steady state kinetics, was given by rH2=0.075e31 kJmol-1/RTxpH2O x pH2-0.5(1-β), where β 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.