Catalytic and physicochemical properties of Pt/α-GeO₂ systems in reaction of selective hydrogenation of α,β-unsaturated aldehydes in a gas phase

Abstract

Hydrogenation of crotonaldehyde in a gas phase over Pt/α-GeO₂ catalysts was investigated. The systems were characterized by BET, XRD, TPR, TEM, ToF-SIMS, and FTIR methods. The optimum pretreatment parameters were studied. The best catalytic performance shows the catalyst 5 wt % Pt/α-GeO₂ (69% selectivity to crotyl alcohol at 200 μmol s⁻¹ g ⁻¹_Pt activity and 10% conversion of crotonaldehyde). Lower loaded catalysts (2 and 1 wt % Pt) show lower, but also promising activity and selectivity. This good catalytic performance was related to the physicochemical properties of the catalyst. GeO₂ in the presence of Pt undergoes a partial surface reduction at temperatures higher than 100°C probably leading to the creation of the active Pt-Ge centers responsible for high selectivity to crotyl alcohol. Reduction at a temperature≥200°C deactivates the catalytic systems due to the formation of inactive PtGe alloys.