and Summary Hydrogenation has been carried out in a“dead‐end” type reactor with various types of nickel catalyst and with automatic recording of hydrogen absorption. Oils with varying concentrations of sulfur and phosporus compounds, fatty acids and their salts, as well as partly oxidized oil have been hydrogenated. The resulting kinetic curves are characteristic for each catalyst type and for each inhibitor. An increase in the poison concentration in the reaction system results in lengthening of the induction period apart from the decrease of catalyst activity.

Hydrogenation was done in a “dead‐end” type of reactor with automatic recording of hydrogen absorption. In order to determine the poisoning rates of various nickel catalysts with phospholipids, allyl isothiocyanate (AITC), free fatty acids, sodium soaps and products of lipid oxidation, these poisons were added to the reaction system while the reaction was approaching the highest rate. The kinetic curves show that, at the moment of inhibitor addition, the reaction rate decreases immediately; for AITC, the reaction is even stopped for a certain period of time. This observation proves inhibitors are adsorbed at the metal surface immediately after introduction to the system. In some cases, after decreasing the reaction rate, we have observed subsequent acceleration of the reaction that may result from depoisoning processes at the catalyst surface.