Hydrogenation of Edible Oils and Fats by Nickel Catalysts. I.

Abstract

Modes of hydrogenation of edible oils and fats were investigated for an estimation of triacylglcerol composition of hydrogenated oil. From the data obtained, the rate o hydrogenation showed no difference in acyl positions and was directly proportional to their unsaturation degree. On the other hand, the formation of trans isomer was essentially the same in 1, 3-and 2-position and was proportional to the decrease of iodine value up to traps equilibrium value, and then the trans isomer decreased with the decrease of iodine value. The selectivities in 2-position tended slightly low, but they were negligible for the estimation of triacylglycerol composition in this report. From the results obtained the authors assume as follows. 1. Hydrogenation with nickel catalysts is the first-order consecutive reaction, and there are no difference in rate of hydrogenation and selectivities (S31, S21) between acyl positions. 2. The trans isomerization is not affected with acyl position, and is in proport on to trans isomerization ratio (TI = Δtrans/ ΔIV) dependent on hydrogenating condition and the traps isomer decreases with iodine value from trans equilibrium value. 3. There is no migration of acyl position during hydrogenation. Using S31, S21 and TI obtained experimentally, fatty acid composition and iodine value of hydrogenated oil were calculated by this simulation. Morever, saturated (S), trans unsaturated (E) and cis unsaturated (U) acid in acyl positions were calculated by this simulation. From the S, E and U calculated, the triacylglycerol compositions of hydrogenated soybean oil, cottonseed oil and rapeseed oil were estimated and illustrated by diagrams.