CS216086B1 - A method for removing and recovering nickel from oils and fats after hydrogenation with homogeneous nickel catalysts - Google Patents

Abstract

The invention relates to a method for removing and regenerating nickel from oils and fats after their hydrogenation catalyzed by homogeneous nickel catalysts. The removal of nickel is carried out by washing the hydrogenated oil or fat with a concentrated mineral acid, preferably phosphoric acid or sulfuric acid, or with its aqueous solution with a concentration higher than 50%, and after separating the aqueous phase, washing the oil thus treated with an alkali metal hydroxide solution, and the regeneration of nickel from the aqueous phase is carried out by its precipitation in the form of nickel carbonate with an aqueous solution of alkali metal carbonate with a concentration of 5 to 20% at a temperature of 40 to 80 °C.

Description

The present invention relates to a process for the removal and regeneration of nickel from oils and fats after their hydrogenation catalysed by homogeneous nickel catalysts.

Hydrogenation of vegetable oils and animal fats is an important process in the fat industry. Up to now, this hydrogenation has been carried out using supported metals, i.e. heterogeneous catalysts, which are usually removed from the reaction mixture after hydrogenation by filtration. It is known that the use of catalyst systems based on Ziegler-type nickel compounds (Yukagaku 24, 11 (1975), Yukagaku 24, 649 (1975), U.S. Pat. 2,258,896 (1974), Germany 2,203,486 (1975), Jap. Patent Application No. 21 082 (1970), Czechoslovakian Authorization Certificate 197 143, Czechoslovakian Authorization Certificate 197 144) enables this process to be carried out under conditions leading to reduced energy costs, while also obtaining fat products of new properties. The poorly effective or inexpensive methods of removing them from the reaction mixture after hydrogenation and the unresolved method of removing them from the reaction mixture after hydrogenation and the hitherto unresolved method of regenerating the nickel component of the catalyst (Yukagaku 24, 649 (1975)) are complicated. certificate 214 591),

According to the process of the invention, the nickel removal is carried out by washing the hydrogenated oil or fat with a concentrated mineral acid, preferably phosphoric acid or sulfuric acid, in an amount of 1.0 to 1.7% by weight, depending on the nickel concentration or aqueous solution of these acids . The nickel components of the catalyst are thereby converted into an aqueous solution in the form of the appropriate soluble salts (nickel dihydrogen phosphate or nickel sulfate). Residual nickel in the oil or fat is removed by treatment with an alkali metal hydroxide at a concentration of 3 to 20%, which nickel passes into the soapstock as an occlusion. Both processes are carried out at a temperature of 40 to 80 ° C, preferably at 60 ° C.

The nickel removal and regeneration process of the present invention can recover at least 95% of the original amount of nickel used as a hydrogenation catalyst. The described method further ensures a perfect separation of nickel from the fat product which contains only 0.01 ppm of nickel, i.e. a residual concentration that is well below the 3 ppm limit permitted for hardened fats and vegetable oils.

After separation of the nickel from the hydrogenated oil or fat as described above, it is recovered from the aqueous solution by precipitation with an aqueous solution of 5-20% alkali metal carbonate at 40-80 ° C as insoluble nickel carbonate which is separated by filtration or centrifugation and used to produce a new catalyst.

The following examples illustrate the process of the invention without limiting or limiting it.

Example 1

22.5 parts of concentrated phosphoric acid at 60 ° C were added to 1500 parts hydrogenation-free rapeseed oil hydrogenation product at 100 ° C, atmospheric hydrogen pressure * in the presence of a catalyst formed by the reaction of nickel stearate with dihydro-bis (2-methoxyethexes) aluminate. C and the mixture was homogenized. After the addition of 150 parts of water and re-homogenization, the reaction mixture was centrifuged to separate the non-soluble aluminum phosphates and the aqueous phase containing dissolved 1.2% nickel dihydrophosphate, which was mixed with 35 parts 20% sodium carbonate solution and formed. the nickel carbonate precipitate was filtered off. The filtrate contained 0.03% nickel, i.e. 2.5% of the original metal. In this way, 97.5% of the original amount of nickel was recovered in the form of nickel carbonate usable for the production of the new catalyst.

Removal of residual nickel in the hydrogenated oil after phosphoric acid treatment was accomplished by adding 37 parts of a 10% aqueous sodium hydroxide solution at 60 ° C. After homogenizing the mixture, the occluded nickel free fatty acid soaps were separated from the oil by filtration. In this way, the residual nickel content of the oil was reduced from 3 ppm achieved with phosphoric acid to less than 0.01 PPm.

Example 2

Example 1 was repeated except that an aqueous solution of 55% phosphoric acid was used instead of concentrated phosphoric acid and the procedure was performed at 80 ° C. An oil containing less than 0.01 ppm of nickel was obtained, with 95% of the original nickel being recovered as nickel carbonate.

Example 3

Example 1 was repeated except that an equivalent amount of concentrated sulfuric acid was used instead of concentrated phosphoric acid and the procedure was performed at 40 ° C. An oil containing 0.01 ppm of nickel was recovered, with 97% of the original amount of nickel recovered as nickel carbonate.

Claims (1)

Process for removing and regenerating nickel from oils and fats after hydrogenation with homogeneous nickel catalysts, characterized in that the hydrogenated oil or fat is washed with a concentrated mineral acid, preferably phosphoric acid or sulfuric acid, or an aqueous solution of more than 50%, aqueous phase The oil thus treated is washed with an alkali metal hydroxide solution having a concentration of 3 to 20% at a temperature of 40 to 80 ° C, preferably 60 ° C, after which the nickel regeneration from the aqueous phase is carried out by precipitation in the form of nickel carbonate with an aqueous alkali carbonate solution. metal at a concentration of 5 to 20% at a temperature of 40 to 80 ° C.