Nickel hydrogenation catalyst for tallow hydrogenation and for the selective hydrogenation of sunflower seed oil and soybean oil

The animal tallow, fats and vegetable edible oils hydrogenation is a very important operation in the chemical and food industry. A catalyst used in the industrial processes of the tallow and fat hydrogenation and in the vegetable oils selective hydrogenation, is a nickel catalyst deposited on a silicate support. A new nickel catalyst supported on a natural silicate diatomite, for tallow hydrogenation and for the selective hydrogenation of sunflower seed oil and soybean oil, has been prepared by the precipitation method. Choice and chemical preparation of the nickel catalyst support, the process of depositing nickel and a promoter on the support, as well as the process of activating them, are all of vital importance for obtaining a highly active hydrogenation catalyst. The synthesis of a nickel catalyst supported on diatomite is a three-stage process: the precursor's synthesis, the dry precursor's reduction and the passivisation combined with impregnation. The final product contains between 20 and 22 wt.% of the reducted nickel within the catalyst mass, about 55 wt.% of the impregnate, while the rest of about 24 wt.% is the support. Checking of the catalyst's activity in the process of tallow and fat hydrogenation has been done with edible tallow at the lab level. The quantity of Ni-catalyst was 0.33 wt.%, which is corresponding to the industrial parameters. Results obtained from the synthesized catalyst samples, demonstrate the final iodine value (I.V.) being between 0.1 and 0.5, corresponding to the decrease of 399-404 units of the I.V. per I g of the nickel used. Testing of the synthesized catalyst's performance in a process of the sunflower oil and soybean oil selective hydrogenation, has been done in an industrial pilot and reactor plant. The experimentally obtained results show that the synthesized catalyst has good catalytic properties in a process of tallow and fat hydrogenation, while demonstrating a high selectivity during the sunflower and soybean oils hydrogenation process; i.e., C18:3 (linolenic)-->C18:2 (linoleic); C18:2 (linoleic)--> C18:1 (oleic) and C18:1 (oleic)-->C18:0 (stearic), respectively. (C) 1998 Elsevier Science B.V. All rights reserved.