Selective epoxidation of methyl soyate over alumina-supported group VI metal oxide catalysts

Epoxidation of methyl soyate (biodiesel), soybean oil and oleic acid with tert.-butyl hydroperoxide (TBHP) was investigated over γ-alumina-supported group VI metal oxides (CrOx/Al2O3, MoOx/Al2O3 and WOx/Al2O3) prepared by impregnation method. The studies revealed that 15 wt% MoOx on γ-Al2O3 was the most active catalyst (conversion >90 mol% under optimized conditions). While MoOx/Al2O3 is selective mainly for epoxidation, the other catalysts are active for epoxidation as well as for decomposition of TBHP. The active species on the catalyst surface were investigated using in situ UV–visible spectroscopy. A linear correlation was observed between epoxidation activity and surface acidity of the catalyst. A new1H NMR method was developed to monitor the progress of epoxidation reaction which was found to be superior to gas chromatographic method in estimating the conversion of double bonds of fatty compounds.

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► Selective epoxidation of methyl soyate over Al2O3-supported group VI metal oxides.
► High conversion (>90%) with 100% epoxide selectivity was obtained over MoOx/Al2O3.
► A new, 1H NMR method is reported to monitor the progress of epoxidation reaction.
► Active sites and structure–activity correlations are reported.