Selectivity and monoene isomerization in the catalytic hydrogenation of polyenoic fatty acid methyl esters

Abstract

In the selective catalytic hydrogenation of methyl esters of polyunsaturated fatty acids, the hydrogenation and isomerization of monoenoic esters is suppressed due to the preferential adsorption and reaction of polyenoate. The monoene isomerization of mixtures of methyl linoleate and methyl oleate had been investigated in a selective hydrogenation using [ 14C]-labeled methyl oleate. Although the degree of isomerization of oleate is rather high under the conditions applied, the monoenoate coverage of the catalyst surface is only a few percent compared with the dienoate coverage at dienoate concentrations higher than 50%. The direct conversion of linoleate to stearate is to a great extent responsible for the formation of stearate in the first stage of the hydrogenation.