THE EFFECT OF FREE FATTY-ACID ON THE REACTIVITY OF COPPER-BASED CATALYSTS FOR THE HYDROGENOLYSIS OF FATTY-ACID METHYL-ESTERS

In the synthesis of fatty alcohols by hydrogenolysis of fatty acid met hyl esters, small amounts of free fatty acids in the feed negatively a ffect the reactivity of copper-silica based catalysts. The effect of t he acid was investigated in relation to the production of water, the n ature of the inhibiting species, and the degree of reduction of the ca talyst. Inhibition is reversible and not due to catalyst deactivation. Water is not the inhibiting species. Furthermore, formation of copper and zinc soaps was excluded. Lauric acid in the methyl ester feed rea cts preferentially, but at a lower rate than the ester. Inhibition mos t likely stems from a preferential adsorption of the acid at the activ e sites of the catalyst. The consequences for practical applications a re discussed.