Water–Gas Shift Activity of Pt Catalysts Prepared by Different Methods

Platinum supported on ceria and zirconia was prepared through different preparation methods: Coprecipitation (CP), spray drying (SD), and flame spray pyrolysis (FSP). The catalysts were characterized by XRD, TPR, N2 adsorption, and H2 chemisorption, and the water–gas shift activity in the range 190–310 ◦C and initial stability at 300–310 ◦C were tested. Although the spray-dried Pt/CeO2/ZrO2 catalyst shows the highest initial activity, it deactivates rapidly at 300 ◦C and levels out at similar activity as the coprecipitated Pt/CeO2 and Pt/CeO2/ZrO2 within a few hours. Flame spray pyrolysis appears to be a promising preparation method concerning the stability of catalysts, although the initial activity is rather poor. High activity is related to high Pt dispersion, low reduction temperature, and small support particles. The support particle size is also much affected by the preparation method.