Single-stage medium temperature water-gas shift reaction over Pt/ZrO2 – Support structural polymorphism and catalyst deactivation

Influence of zirconia polymorphism on water-gas shift reaction was investigated. The study was carried out over catalysts with similar features, which allowed assessing any effect brought about by the support crystalline structure. It was found that zirconia polymorphism determines the catalyst activity and the monoclinic structure renders a more active system. It is most likely due to the presence of hydroxyl groups, which have been claimed to be involved in the formation of important reaction intermediates. Catalyst deactivation was also addressed and it could be concluded that the changes in metal phase dispersion along reaction play a quite important role on the ZrO2-supported catalyst stability.

Zirconia polymorphism does play an imperative role in determining the catalyst activity, being the monoclinic structure the one rendering the more active system. The deactivation of water-gas shift catalysts may be reasonably described by considering the drastic changes in the metal phase dispersion along reaction as determined over both polymorphic samples presented in this work.Figure optionsDownload as PowerPoint slideHighlights
► Platinum catalysts prepared over commercial monoclinic and tetragonal ZrO2.
► Polymorphic catalysts for single-stage medium temperature water-gas shift reaction.
► The monoclinic structure renders the more active system.
► Deactivation is associated with the decrease of platinum dispersion upon reaction.