Pt-Re bimetallic supported on CeO2-ZrO2 mixed oxides as water-gas shift catalysts

The addition of Re to Pt/Ce0.46Zr0.54O2 was shown to enhance the water-gas shift (WGS) rate compared with the rate observed with Pt alone supported on either Ce0.46Zr0.54O2 or Ce0.6Zr0.4O2 at similar Pt weight loadings. The results from CO chemisorption showed that the Pt was more highly dispersed on Pt-Re/Ce0.46Zr0.54O2 than on the Pt/Ce0.46Zr0.54O2 or Pt/Ce0.6Zr0.4O2. Based on this Pt dispersion, the exposed Pt surface area was calculated for Pt-Re/Ce0.46Zr0.54O2, Pt/Ce0.46Zr0.54O2 and Pt/Ce0.6Zr0.4O2. The WGS rate was observed to be proportional to the exposed Pt surface area for the Pt-Re and Pt catalysts; however, the rate per m2 of exposed Pt for Pt-Re/ Ce0.46Zr0.54O2 was higher than that of Pt/Ce0.46Zr0.54O2 or Pt/Ce0.6Zr0.4O2. The difference in the rates upon the addition of Re to Pt WGS catalysts suggests that the role of Re in enhancing the WGS activity of Pt is more complex than to just increase the Pt dispersion.