THE EFFECT OF TEMPERATURE DURING SOYBEAN OIL HYDROGENETATION ON NICKEL CATALYST POISONING BY PHOSPHOLIPIDS.
 
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Pol. J. Food Nutr. Sci. 2003;53(4):19–23
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ABSTRACT
The effect of temperature during hydrogenation of soybean oil on the degree of poisoning of nickel catalyst by phospholipids was investigated. Two wide porous catalysts with diverse particle sizes were used: catalyst No. 1, medium-grained and catalyst No. 2, fine-grained. Hydrogenation was conducted in a “dead end’’ type laboratory scale reactor in the temperature range of 160¸190oC. The poisoning coefficient (the ratio of the hydrogenation rate constants in the presence and in the absence of inhibitors in the oil, a = K with inhib./K without inhib.) and changes in activation energy (Ea) of soybean oil hydrogenation in the presence of phospholipids were studied. It was affirmed that the effect of temperature on catalyst poisoning by phospholipids is significant; the lower the reaction temperature was, the greater the phospholipid inhibiting effect was. The fine-grained catalyst was more active and more resistant. Its resistance decreased at a slower rate than that for the medium-grained catalyst. For example, at 160oC the coefficients (a) were 0.26 and 0.4 for catalyst No. 1 and 2, respectively. But at 190oC, the respective coefficients were 0.59 and 0.66. The studied catalysts were characterized by Ea similar to that of commercial catalysts: 35.21 and 28.66 kJ/mol for catalysts No. 1 and 2, respectively. The addition of phospholipids to soybean oil caused a decrease in the reaction rate and an increase in the activation energy. The absolute difference in activation energy (DEa) for the medium-grained catalyst was 44.05 kJ/mol, and was almost two times higher than that for the fine-grained catalyst (DEa = 26.02 kJ/mol). The relative increase in activation energy was 125 and 94.3 %, respectively.
ISSN:1230-0322