Redox behaviour of ceria-titania mixed oxides

The reducibility of the supports is one of the properties influencing the catalytic behaviour of platinum catalysts in the selective hydrogenation of alpha,beta-unsaturated aldehydes. Platinum on reducible supports has shown higher selectivities in carbonyl hydrogenation compared to Pt/Al2O3 and Pt/SiO2 catalysts. We report here a study on the redox properties of mixtures of titania and ceria, precursors of Pt/TiO2-CeO2 catalysts. Two samples, with atomic compositions Ti/Ce 8/2 and 5/5, were prepared using a sol-gel process. They were treated under hydrogen and air in a wide range of temperatures. Surface compositions and the percentage of reduced ceria were determined by X-ray photoelectron spectroscopy. Temperature programmed reduction (TPR) profiles, and X-ray diffraction patterns were interpreted in terms of the formation and stability of several mixed compounds. (C) 2000 Elsevier Science B.V. All rights reserved.