Promoting Effect of Ceria on the Gas Phase Hydrogenation of Crotonaldehyde over Platinum Catalysts

Abstract

The platinum-ceria interaction, induced after high temperature reduction of platinum based catalysts, has been used to improve the selectivity towards crotyl alcohol in the gas phase hydrogenation of crotonaldehyde. Three catalysts have been used in this study, Pt/SiO2, Pt/CeO2, and Pt/CeO2/SiO2. They have been characterized by X-ray diffraction and temperature-programmed reduction, and their catalytic behavior in the gas phase benzene hydrogenation and crotonaldehyde hydrogenation reactions have been determined after reduction treatments in flowing hydrogen at 473 and 773 K. Results obtained in the gas phase hydrogenation of crotonaldehyde show that the presence of ceria clearly promotes the hydrogenation of the carbonyl bond when the sample is reduced at high temperature, this being attributed to the presence of oxygen vacancies or Ce3+cations in the neighbourhood of platinum particles, induced by the thermal treatment under hydrogen. The promoting effect is more important for Pt/CeO2; crotonaldehyde hydrogenation on this catalyst yields up to 80% crotyl alcohol after reduction at 773 K, whereas it produces 100% butanal after reduction at only 473 K.