The role of surface carboxylates in catalytic ozonation of acetone on alumina-supported manganese oxide

This study addresses gas phase reaction of acetone with ozone on alumina-supported manganese oxide catalyst, the reaction intermediates, and the reaction pathways. Catalytic ozonation was conducted at 25 and 90 degrees C. X-ray photoelectron spectroscopy, X-ray absorption near edge structure and a number of temperature programmed analyses were used to characterize the catalyst and investigate the nature and role of reaction intermediates. It was found that Mn2O3 was the major manganese phase on the catalyst. During the reaction, alumina interacted effectively with the adsorbed acetone to create surface carboxylate intermediates such as acetate; and ozone enhanced formation of these intermediates. The presence of manganese sites was necessary to further oxidize the surface carboxylates. A stable catalytic activity was achieved at 90 degrees C. However, at 25 degrees C, byproducts such as acetic acid and acetic anhydride, produced from incomplete oxidation accumulated on the surface of the catalyst and reduced the catalyst activity Deactivation caused by these byproducts could be reversed by their desorption from the surface of the spent catalyst at 425 degrees C. (C) 2017 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.