Reactions of ethanol over metal oxides

The reaction of ethanol over a series of oxides (Fe2O3, Fe2O3/CaO, Fe3O4, TiO2, CaO, and SiO2) has been investigated. The main reaction product in all cases is acetaldehyde, with secondary products acetone and ethyl acetate. At 473 K, the rate Constant k decreases according to the series Fe2O3 > Fe3O4 > CaO > TiO2 >> SiO2. Titration of basic sites by CO2 adsorption at room temperature shows that the reaction rate can be successfully normalised by basic site density for oxides that adsorb CO2 except for CaO. Acetone production, presumably via acetate ketonization, is highest over TiO2 while ethyl acetate formation, by Tishchenko reaction, is highest over Fe2O3. (C) 2000 Elsevier Science B.V. All rights reserved.