CeOx/TiO2 (Rutile) Nanocomposites for the Low-Temperature Dehydrogenation of Ethanol to Acetaldehyde: A Diffuse Reflectance Infrared Fourier Transform Spectroscopy-Mass Spectrometry Study

Two nanocomposites of different layer thicknesses were synthesized by impregnation of a rutile titania support with a reduced ceria solution. An in situ diffuse reflectance infrared fourier-transform spectroscopy-mass spectrometry study of these materials, compared with the parent single oxides, has shown remarkable differences in the interaction with ethanol depending on the layer thickness and the environment (oxidizing/reducing). Under anaerobic conditions, it was found that the surface-support interaction stabilized the ceria in the reduced form (Ce3+) in a wide range of temperature. The intrinsic characteristics of these materials were proven useful in the dehydrogenation of ethanol to acetaldehyde at low temperature since they inhibited further oxidation products (typical in the case of bulk ceria) and dehydration products (such as ethylene, the main product for bulk titania), and even promoted aldolic condensation to crotonaldehyde due to their modified acid/base properties. Interestingly, this highly selective oxidation is obtained without the need of using expensive noble metals as catalysts or hydrogen to keep the ceria reduced.