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The effects of metathesis for concentrating the tocopherols from soybean and rice-bran scum oils were studied by using the batch reactor under helium atmosphere. The contents of tocopherols in the scum oils decreased conspicuously when heated under air atmosphere or when kept in hexane solution above 5 days even at room temperature. The sterols in the scum oils were removed by the mixed solvent method. Metathesis of the sterol-removed scum oils in hexane was performed over Re207/A120, and W03 /A120, catalysts, and the concentrate was obtained by distillation in vacuum at 1901C. The effect of metathesis was evaluated as relative ratio of a-tocopherol in the concentrate to that in scum oil. The maximum ratio for both scum oils was obtained on 12.8%(w/w)Re,0,/Al2O, catalyst which formed effectively the active sites for metathesis by the reaction between the added tetramethyltin and Re20, on the surface of the catalyst. The optimum amount of the catalyst was 0.5g per 10g scum oil, and the optimum reaction temperature was 25°C for both scum oils. The metathesis was more effective in rice-bran scum oil than in soybean scum oil. These facts indicated that the tocopherols in the scum oils can be highly concentrated by applying metathesis.
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