Catalysis by Heteropoly Compounds. XVIII. Oxidation of Methacrylaldehyde over 12-Molybdophosphoric Acid and Its Alkali Salts

Article abstract of DOI:10.1246/bcsj.64.243

The reaction scheme for the methacrylaldehyde oxidation over heteropoly compounds proposed previously (M.Misono et al., Proc. 7th Intl.Congr.Catal., 1980) was confirmed by 18O tracer experiments using the Pulse-MS method (combination of pulse reactor/mass spectrometer).The occurrence of direct and rapid oxygen exchange between methacrylaldehyde and the polyanion of MxH3-xPMo12O40 (M=Na, Cs, x=0-3.15) was verified under the reaction conditions.The results also suggested that this reaction is catalyzed by Broensted acid sites of the catalysts via such intermediates as (I) and/or (II) in scheme 1.It was shown that the methacrylaldehyde oxidation is a surface-type reaction and the catalytic activity is controlled by the oxidizing ability of the catalyst surface.