Acetaldehyde Adsorption and Reaction on CeO2(100) Thin Films

This study reports and compares the adsorption and dissociation of acetaldehyde on oxidized and reduced CeOx(100) thin films. Acetaldehyde reacts and decomposes on fully oxidized CeO2(100), whereas it desorbs molecularly at low temperature on CeO2(111). The primary products are CO, CO2, and water along with trace amounts of crotonaldehyde and acetylene. The acetaldehyde adsorbs as the eta-acetaldehyde species, dioxyethylene. Decomposition proceeds by dehydrogenation through acetate and enolate intermediates. The reaction pathway is similar on the reduced CeO2-x(100) surface; however, the inability to react with surface O on the reduced surface results in H-2 rather than H2O desorption, and C is left on the surface rather than producing CO and CO2. C-O bond cleavage in the enolate intermediate followed by reaction with surface H results in ethylene desorption.