Selective oxidation of n -buthanol to butyraldehyde over MnCo 2 O 4 spinel oxides.

Partial oxidation of n -butanol to butyraldehyde, propionaldehyde and acetaldehyde over MnCo 2 O 4 spinel oxides has been investigated. Physicochemical characteristics of samples, prepared by co-precipitation with different amounts of precipitating agent, were studied by XRD, N 2 adsorption-desorption isotherms, FT-IR, SEM and XPS. The ratio between the precipitating agent and the precursors has a considerable influence both on the structure, which is evidenced by XRD, due to switching from a crystalline structure to an amorphous one and on the surface (XPS) by an obvious change in the ratio Co 3+ /Co 2+ and Mn 4+ /Mn 3+ and in the content of oxygen vacancies. The reaction rate is not influenced by the oxygen pressure, emphasizing that n -butanol oxidation occurs through the Mars van Krevelen mechanism. The conversion of n -butanol and yield of butyraldehyde are directly proportional to the cobalt content on the surface, while the propionaldehyde yield is proportional to the Mn 4+ /Mn 3+ ratio.