Selective hydrogenation of oo-rapeseed oil with Cu/Cr catalyst.I.The reaction kinetics and fatty acid composition

The reaction kinetics and basic fatty acid transformations during selective hydrogenation of OO-rapeseed oil with Cu/Cr and Ni catalysts were compared. With the Ni catalyst the reaction rate was higher than with the Cu/Cr catalyst, thus, 30-fold higher concentration of the latter was used in the experiments. The reaction sequence covered 3 stages: (1) an induction (catalyst activation), (2) intensive hydrogenation of trienes (I), (3) hydrogenation of dienes (II). The rate of (2) increased with the concentration of both catalysts, however, with the Cu/Cr catalyst it depended on temperature more than with the Ni catalyst In the presence of the former, mainly trienes were reduced which yielded the increase in monoenes and slight changes in dienes. The content of saturates did not change. The selectivity for the reduction of trienes was higher than that of dienes. A complete reduction of linolenic acid occurred at the iodine value drop by about 20 units. The rate of hydrogenation process in the diffussion region of reaction was lower than that in the kinetic region. The reaction region did not affect the fatty acid transformations.