CS241216B1 - Method of selective nickel catalyst preparation on carrier for hydrogenation - Google Patents

Description

The present invention relates to a process for preparing a selective supported nickel catalyst, particularly suitable for the hydrogenation of polyunsaturated fatty acids and their esters in vegetable oils and animal fats to di- or monounsaturated compounds.

Nickel catalysts (mostly supported on silica gel) have been used for the hydrogenation of vegetable oils and animal fats since 1902, when W. Normann first used reduced nickel for this purpose. Over the years, a number of processes have been proposed for the preparation of nickel catalysts, differing in the precipitation method, the kind of starting salt, the precipitant and the carrier or the type and content of modifiers which are usually metals such as copper, silver, chromium, zirconium, thorium, tin, rhenium. and metals VIII. groups of the periodic system. The use of modifiers aims not only to achieve a higher activity of the resulting nickel catalyst, but also to improve its selectivity. In recent years, it has been recommended for the selective hydrogenation of polyunsaturated organic compounds to include catalysts which contain as an active ingredient a nickel boride formed by the action of an alkali borohydride on a soluble or insoluble nickel salt (U.S. Pat. No. 2,461,661). These. however, catalysts have not found widespread use in industrial practice, mainly for economic reasons (high consumption and cost of alkali borohydrides).

Therefore, other ways have been sought to increase the activity and selectivity of the selective hydrogenation catalyst. One of these is a process starting from a process for preparing a nickel catalyst, comprising precipitating a nickel salt on a carrier with alkali and reducing the obtained nickel hydroxide or nickel carbonate hydroxide with hydrogen (U.S. Pat. Nos. 111791 and 130 468). This method is modified by subjecting the resulting nickel hydroxide or nickel carbonate hydroxide precipitate to an alkali borohydride solution and the resulting catalyst, after reduction with hydrogen, exhibits substantially higher activity and selectivity for hydrogenation of polyunsaturated compounds (cf. no. 211 004).

Further research has found that high selectivity and nickel catalyst activity can be achieved if the nickel hydroxide or nickel carbonate-hydroxide is gened to polyunsaturated compounds (Czechoslovak auto metaborate).

Based on this finding, the present invention is directed to a process for preparing a selective supported nickel catalyst for the hydrogenation of polyunsaturated fatty acids and their esters in vegetable oils and animal fats comprising precipitation of a soluble nickel salt alone or with the addition of copper, silver, chromium, zirconium salts , thorium, tin, rhenium or a metal VIII. from 0.1% to 10% by weight of alkali to form nickel hydroxide and / or nickel hydroxide carbonate

NiCCB. x Ni (OH 2, y H 2 O, where x and y is from 1 to 30, filtration, washing, drying and reduction with hydrogen.) The present invention is based on a process in which a nickel hydroxide and / or nickel carbonate hydroxide precipitate at a pH greater than 9 5 for 10 to 120 minutes at a temperature of 20 to 98 ° C with a solution of alkaline metaborate and ammonia and / or an ammonia-derived compound, preferably an ammonium salt, in a molar ratio of 1: 1 in such an amount that the final concentration of these substances in 1 liter of suspension containing 2 to 5% by weight of solid precipitate particles is in the range of 0.002 to 0.3 mol.

Due to the action of the alkali metaborate under the above conditions on the catalyst precursor, some hydroxyl or carbonate ions are substituted with borate and the resulting catalyst, after reduction with hydrogen, exhibits several times higher activity and selectivity than conventional catalysts.

The process of preparing the catalyst of the invention has the advantage of lower costs compared to processes based on the use of alkali metal borohydrides. An important benefit is also an increase in work safety: borohydrides are toxic substances causing skin irritation and burns. Alkaline metaborites, on the other hand, are completely harmless in contact with the skin.

The process for preparing the nickel catalyst of the present invention and its effects are further illustrated by the following examples.

He did

To the sodium carbonate solution at 98 ° C was added a slurry of diatomaceous earth in a solution of 76.3 g NiCl. 6 H 2 O and precipitation was completed by addition of sodium hydroxide. The resulting suspension, containing 3.8 wt. % of the precipitate solids were then treated at this temperature for 15 minutes at pH 13.9 with a 1: 1 molar ratio of sodium metaborate and ammonium chloride, both amounts. of substances in 1 liter of suspension was 0.003 mol. The precipitate was then filtered off, washed and, after drying, reduced at 450 ° C for 2 h. The catalyst thus obtained was in an amount of 0.025% by weight. Ni used to hydrogenate soybean oil. At 180 ° C, an iodine value reduction of 30 units was achieved in 4 times less time than under the same conditions using a catalyst prepared in the same manner, but without the action of sodium metaborate and the ammonium salt. The selectivities varied about tenfold.

4 12 1 7

Example 2

Into a slurry of diatomaceous earth in a solution containing 90 g of NiSO4. 7 H 2 O was added at 20-25 ° C to a 1: 2 molar k nickel solution containing simultaneously sodium metaborate and dimethylformamide in a 1: 1 molar ratio, resulting in a concentration of 0.2 mol per liter of suspension which after precipitation of nickel sulfate, it contained 2.6 wt. % solid catalyst precursor solids. The temperature was then raised to 95 ° C and maintained at this value for 120 min at pH 10. After filtration, washing and drying, the precipitate obtained was reduced at 490 ° C for 1 h. The catalyst obtained was used in an amount of 0.05 wt. percent Ni to hydrogenation of rapeseed oil at 180 ° C. Its activity was three times higher and the selectivity was eight times higher than that of a catalyst obtained in a similar manner, but without the action of sodium metaborate and dimethylforamide.

Example 3

To a slurry of diatomaceous earth in a solution of 90 g NiSOa. A solution containing 47.5 g of sodium carbonate was added over 1 hour at 75 ° C. The resulting slurry containing 4.5 wt. % of solid catalyst precursor particles, a solution containing sodium metaborate and ammonium sulfate in an equimolar ratio was added in such an amount that the final concentration of both substances in 1 liter of suspension was 0.08 mol. The suspension was then heated at 100 ° C for 2 h at pH -10. After filtration, washing and drying, the precipitate obtained was reduced at 450 degrees Celsius for 2 h. The catalyst obtained exhibited virtually the same properties as the catalyst described in Example 2.

Claims (1)

A process for preparing a selective supported nickel catalyst for the hydrogenation of polyunsaturated fatty acids and their esters in vegetable oils and animal fats, comprising precipitating the nickel salt alone or with the addition of copper, silver, chromium, zirconium, thorium, tin, rhenium or a metal VIII. % of the periodic system in an amount of 0.1 to 10 wt.%, with alkali to form nickel hydroxide and / or nickel hydroxide carbonate of the composition N1CO3. x Ni (OH) ₂ . у H 2 O, where x and 1 1 to 30 are filtered, washed, dried and reduced with hydrogen, characterized in that the precipitate of nickel hydroxide and / or nickel hydroxide carbonate is treated at a pH higher than 9.5 for 10 to 120 minutes at 20 to 98 ° C with a solution of alkaline metaborate and ammonia and / or an ammonia-derived compound, preferably an ammonium salt, in a molar ratio of 1: 1 in such an amount that the final concentration of these substances in 1 liter of suspension contains 2-5 . % solids of the precipitate are in the range of 0.002 to 0.3 mol.