CS215977B1 - A method for purifying cobalt-phosphine catalyst compositions - Google Patents

Abstract

A method for purifying mixtures containing cobalt phosphine catalyst by reacting the cobalt phosphine catalyst with an acid at elevated temperature, wherein the reaction is carried out at a temperature of 20 to 180 °C in the presence of 1 to 8 equivalents, based on cobalt, of sulfuric, acetic or sebacic acids. The method can be used to purify mixtures containing cobalt phosphine catalysts after oxosynthesis, hydrogenation and alcohol synthesis, and especially boiler residues in the petrochemical industry. The method greatly reduces the corrosive effect of acids contained in organic media, eliminating the need for stirring to ensure effective contact of the reactants, since a homogeneous mixture is formed when using the acids according to the invention.

Description

The invention relates to a process for the purification of mixtures containing cobalt-phosphine catalysts, and generally to petrochemical synthesis. The process according to the invention can purify mixtures containing cobalt-phosphine catalysts after undergoing oxosynthesis, hydrogenation and alcohol synthesis. This method is particularly suitable for the extraction of cobalt from that portion of the boiler residue collected for disposal that circulates during production together with the catalyst.

Methods for purifying mixtures resulting from these processes are commonly known in which ae uses cobalt carbonyl. These processes are based on the thermal cleavage of cobalt carbonyl at a temperature of 150 to 300 ° C and a pressure of 1 to 30 MPa.

Methods for purifying mixtures based on the oxidative cleavage of cobalt carbonyl and oxygen, hydrogen peroxide and other substances in an acidic environment at a temperature of 20 to 10 ° C and at atmospheric pressure are also known.

These processes have not been shown to be suitable for the purification of mixtures containing cobalt-foaffin catalysts since these cobalt-foaffin catalysts are thermally stable and do not decompose when oxidized.

It is also known to eliminate cobalto-phosphine catalysts, for example according to U.S. Pat. No. 3,530,190, which consists in treating a mixture comprising cobalto-phosphine catalysts with hydrocyanic acid, its salts and optionally compounds with aldehydes with cyanohydrins. The disadvantage is that toxic substances must be used in this procedure.

Also known is a process for treating cobalt-phosphine catalyst compositions according to U.S. Pat. No. 3,418,351, which excludes a cobalt-phosphine catalyst by treating the composition containing it with carbon monoxide at a pressure ranging from 1.0 to 5 MPa at a temperature in the range of SO to 100 ° C, and at a pH of 3 to 8. In this treatment, carbon monoxide is added to the cobalt-phosphine catalyst and the complex compound becomes insoluble, which is then precipitated by conventional methods. When separating the cobalt-phosphine catalyst in this way, the catalyst does not completely fall out, the residue remains in the mixture. About 70% of this catalyst falls out.

The process of the present invention is most closely related to the cobalt phosphine catalyst regeneration process described, for example, in US-AO No. 420,352, which may be regarded as a starting technology for the process of the invention, consisting in treating the oxosynthesis product and an aqueous acid solution while heating. The process is carried out at a temperature of 30 to 120 ° C and with vigorous stirring. The aqueous acid solution layer is neutralized with alkali in the presence of an organic solvent and an oil soluble acid to recover cobalt and phosphine.

The aqueous acid solutions used to carry out this process have a great ability to form corrosion. In addition, acid neutralization in the subsequent regeneration of cobalt and phosphine is desirable. Moreover, the implementation of this process is made more difficult by the existence of cobalt-containing waste waters which are difficult to detect.

Intensive stirring is required for the success of this reaction to ensure good contact of the organic phase, which is a cobalt-free product, and the aqueous phase, which is an acid solution.

If aqueous acid solutions are used, if the temperature exceeds 100 ° C, higher pressures must also be used, which also makes it difficult to separate the cobalt-phosphine catalyst separation process.

Notwithstanding some of the advantages of this method of purifying mixtures containing a cobaltophosphine catalyst, its use in large scale production is still limited.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a change in the cleaning technology for cobalt-phosphine catalyst compositions, good contact of the phase reactants, eliminate the need for increased pressures, eliminate the risk of corrosion, and prevent cobalt-containing waste water.

The problem has been solved and the disadvantages of the known methods have been eliminated in a process for the purification of mixtures containing a cobalt-phosphine catalyst by reacting a cobalt-phosphine catalyst with an acid at elevated temperature according to the invention. % of an acid selected from the group consisting of sulfuric, acetic and sebacic acids in an amount of 1 to 8 equivalents, calculated on cobalt.

By implementing the process for purifying the cobalt-phosphine catalyst compositions of the present invention under these conditions, the corrosive effect of the acids present in the organic media is greatly reduced. This eliminates the need for agitation, as opposed to prior art processes, where agitation is necessary to ensure effective contact of the reactant and make the system homogeneous.

In the process of purifying the cobalt-phosphine catalyst compositions using an acid that is soluble in the composition to be treated, a homogeneous mixture is formed which provides the desired contact of the reactant.

The inorganic acid or organic acid is preferably used as the acid which is soluble in the mixture to be treated, with sulfuric acid being used as the inorganic acid and acetic or sevic acid as the organic acid. Sulfuric acid has a high reactivity and its use makes it possible to reduce the reaction temperature in the process.

Acetic acid and sebacic acid dissolve well in the substances used in the process of the invention. The reaction capacity of these acids is sufficiently high.

The most economical reaction rates can be achieved at elevated temperatures, especially at temperatures within the temperature range.

Since the reaction system is free of water, the reaction temperature can be raised to above 100 ° C without the need to increase the pressure.

In order to further illustrate the method of the invention, an embodiment of the method of the invention is described in detail, first generally and then in the form of individual exemplary embodiments.

The process for purifying the cobalt-phosphine catalyst compositions of the invention is carried out as follows. The starting material used in the process according to the invention is a product which is obtained during oxosynthesis, alcohol synthesis and, optionally, hydrogenation, and contains a cobaltophosphine product, as well as an acid soluble in the mixture to be treated.

The solution containing the cobalt-phosphine complex to be cleaved with subsequent elimination of the components - cobalt and phosphine - and in some cases the excess phosphine is mixed with acids. The acids used are organic or inorganic acids. As inorganic acids, acetic acid and other monocarboxylic acids as well as adipic acid and sebacic acid dicarboxylic acids are used. The acids are used in a ratio of 1 to 8 equivalents, calculated on cobalt. The mixing of the treated mixture with the acid can be carried out at normal or up to 180 ° C elevated temperature. It is also possible to add cold acid to the heated mixture.

Mixing is only necessary to achieve a homogeneous mixing of the treated mixture with the acid. Further forced agitation is not necessary for the reaction to proceed. The acid may be added either at one time at the start of the process or in batches during the process, or even continuously.

The reaction is carried out at 20 to 180 ⁰ C and is excreted when the carbon monoxide and hydrogen and ee color varies from red or brown to strong purple. This color change shows the transition of cobalt to ionic form. The course of the reaction is usually accompanied by the precipitation of cobalt salt. The reaction time is 5 minutes to several days, depending on the temperature and concentration of the reactants.

The whole process can be carried out in a flow-based system or in a periodic system. Reaction apparatuses of any embodiment, including columns, can be used. The mixing can be carried out by means of mechanical stirrers, gas bubbling and, if necessary, a circulation pump.

A prerequisite for the successful elimination of phosphine is that the entire process, including auxiliary operations, is carried out without access to air oxygen.

After heating, the mixture is cooled and then worked up in a conventional manner. The precipitated cobalt salt may be filtered, centrifuged, set aside, and optionally dissolved in specially introduced water.

The remaining solution, already cobalt-free, can be pumped off to eliminate phosphine by distillation, rectification and optionally crystallization.

Example 1

150 g of a product containing 3.9% by weight of a cobalt-phosphine complex with 0.075 g of cobalt, 7% by weight of a 1-phosphine attribute, 55% by weight of alcohols C8 to _C12 and 15% by weight. of C12 alcohol, 12.6 g of acetic acid, equivalent to cobalt, was added.

The resulting homogeneous solution was allowed to stand for 40 minutes at 120 ^° C.

Gas evolution occurred. The color of the falling product varied from brown to strongly lilac, indicating the transition of cobalt to ionic form.

After cooling and standing, the residual cobalt content in the organic layer was 0.011% by weight, corresponding to an extraction degree of 98%.

Example 2

To 12 g of a product containing 2.0 wt. % cobalt-phosphine complex with 0.042 g of cobalt, 7 wt. % tributylphosphine and 65 wt. of ^G 12 ^{+ C} 15 'alcohols were added 0.6 g of acetic acid, which is approximately 3 equivalents, calculated on cobalt. The resulting homogeneous rust flow was allowed to stand for 40 minutes at 150 ^° C.

Gas evolution followed. The color of the falling product varied from red to strongly lilac, indicating the transition of cobalt to ionic form.

After cooling and standing, the residual cobalt content in the organic layer was 0.85% by weight, corresponding to an extraction rate of 86%.

Example 3

8 g of a product containing 2.4 wt. % cobalt-carbonyl complex containing 0.032 g cobalt, 7 wt. % tributylphosphine and 65 wt. of C ^ C + alcohols was added 0.4 g of sulfuric acid, which is approximately 7 equivalents, calculated on cobalt. The resulting solution was allowed to stand for 40 minutes at 120 ^° C.

Gas evolution followed. The color of the precipitated product varied from brown to light yellow, while a light violet deposit was precipitated, indicating the transition of cobalt to ionic form.

After cooling and standing, the residual cobalt content in the organic layer was 0.85% by weight, corresponding to an extraction rate of 99%.

Example 4

K6 g of a product containing 2.4 wt. % of cobalt-carbonyl complex with 0.032 g of cobalt, 7 wt. % tributylphosphine and 65 wt. of cyclododecin was added 0.4 g sulfuric acid, which is 7 equivalents, calculated on cobalt. The obtained homogeneous solution was allowed to stand for 6 hours at 20 ^° C. _I

Gas evolution followed. The color of the falling product became lighter, indicating the transition of cobalt to the ionic form.

After cooling and standing, the residual cobalt content in the organic layer was 0.12% by weight, corresponding to an extraction rate of 70%.

Example 5

To 8 g of a product containing 2.4% by weight of cobalt-carbonyl complex with 0.032 g

4-cobalt, 7 wt.%, Tributyl foaffin, 65 wt. % of ^C 8 ^{+ C} 12 alcohols and 15 wt. of sulfuric acid was added in the amount of 3.5 equivalents, calculated as cobalt. The resulting homogeneous solution was allowed to stand for 6 hours at 20 ° C.

Gas evolution occurred, the color of the falling product became lighter, indicating the transition of cobalt to ionic form. After cooling and standing, the residual cobalt content in the organic layer was 0.1% by weight, corresponding to an extraction rate of 75%.

Example 6

To 9.6 g of a product containing 1.1% by weight of cobalt phosphine complex with 0.0115 g of cobalt, 7% by weight, tributylphosphine, 65% by weight. alcohols of Cg-C ₁₂ and 15% hmot.alkoholu was added 3.3 g · sebacic acid, which is 8 equivalents, relative to cobalt. The resulting homogeneous solution was allowed to stand for 1 hour at 180 ° C.

Gas evolution occurred and the color of the falling product varied from red to intensely lilac, indicating the transition of cobalt to ionic form. After cooling and standing, the residual cobalt content in the organic layer was 0.11% by weight. with 0.11 g of cobalt, corresponding to an extraction rate of 90.8%.

EXAMPLE 7 9.6 g of a product containing 1.1 wt. of cobalt-phosphine complex with 0.12 g of cobalt 7 wt. % tributylphosphine, 65 wt. % of alcohols Οθ + C ^ ₂ and 15 wt. of alcohol C1 was added 0.4 g of sebacic acid in an amount of 0.4 g, equivalent to cobalt. The resulting homogeneous solution was allowed to stand for 1 hour at 180 ° C.

Gas evolution occurred and the color of the falling product changed from strong red to intensely lilac, indicating cobalt transition to ionic form. After cooling and standing, the residual cobalt content in the organic layer was 0.13% by weight, corresponding to an extraction rate of 89.3%.

Claims (1)

A process for purifying cobalt-phosphine catalyst mixtures by reacting a cobalt-phosphine catalyst with an acid at elevated temperature, characterized in that the reaction is carried out at a temperature of 20 to 180 ° C in the presence of an acid selected from sulfuric, acetic and sebacic acid. up to 6 equivalents, calculated on cobalt.