SELECTIVE HYDROGENATION OF ACETIC-ACID TOWARDS ACETALDEHYDE

As a model reaction for the selective hydrogenation of carboxylic acids towards aldehydes, the reaction of acetic acid towards acetaldehyde has been investigated. Various oxides are used as catalysts, including platinum-enriched oxides. It appeared that oxides with a moderate metal-oxygen bond strength are good catalysts, provided that a source of activated hydrogen is present. On exposure to molecular hydrogen zero-valent metals can produce activated hydrogen. Addition of precious metals, such as Pt, or completely reducing part of the oxidic catalyst can provide the zero-valent metal. The hydrogenation probably occurs on the oxidic surface by a Mars and Van Krevelen type of mechanism.