(132e) Conversion of Short Aldehydes From Bio-Mass Over CexZr1-XO2

Coupling and condensation reactions are an important route for converting small oxygenates found in bio-oil into transportation fuels or fuels additives. Aldehydes and carboxylic acids possess reactive carbonyl moieties which can be leveraged to carry out carbon-carbon bond forming reactions, increasing the molecular weight of the oxygenate stream. In this study, aldol condensation and coupling reactions of propanal were investigated over Ce_xZr_1-xO₂ mixed oxide. The reactions were tested in an integral flow reactor at atmospheric pressure. Over Ce_xZr_1-xO₂ mixed oxide, 3-pentanone, 2-methyl-2-pentenal and other higher oxygenated compounds are produced. The highest selectivity to 3-pentanone was observed with He, followed by CO₂ and H₂. It was found that the oxygen storage capacity of the mixed oxide plays an important role in the transformation of the aldehyde to the corresponding acids on the surface, that subsequently couple to give the ketones. The effect of addition of acids and water on the conversion of propanal was tested. The addition of acids and water increased the catalytic activity and promoted ketonization reactions, while it suppressed aldol condensation. The changes in the composition of the ceria-zirconia mixed oxide catalyst showed that with increasing zirconia content, aldol condensation is favored over ketonization.