JPH066604B2 - Method for removing nickel, aluminum and chlorine compounds from olefin oligomers - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for removing nickel, aluminum and chlorine compounds remaining in solution in a crude olefin oligomer obtained by a dimerization and / or codimerization reaction of a monoolefin.

Dimerization of mono-olefins, for example C2-C4 mono-olefins such as ethylene, propylene, 1- or 2-butene in the presence of a nickel salt or a hydrocarbon-soluble nickel complex and a mixture of organoaluminum chlorides. And / or a method of co-dimerization reaction is described in US Pat. No. 3,655,810, European Patent 12685, French Patent 246424.
It is known as Japanese Patent No.

However, when carried out on an industrial scale, various applications of olefin oligomers often require the removal of inorganic components of the catalyst that remain in the olefin oligomer and act unacceptably.

Impurities such as these cannot be removed by simply washing the crude olefin oligomer with water. The reason for this is that washing with water produces a gelatinous precipitate of aluminum hydroxide, which increases the production of chlorinated hydrocarbons.

Another reason is that an insoluble mixture of nickel hydroxide and colloidal metallic nickel is produced, and it is difficult to remove these from the olefin oligomer.

Further, most of nickel is soluble in the crude olefin oligomer and remains in the olefin oligomer as a stable complex, which is decomposed by the reboiler in the next distillation step.

Treatment with an aqueous solution of alkali hydroxide can prevent the formation of a gelatinous precipitate of aluminum hydroxide, but cannot prevent the formation of chlorinated hydrocarbons.

A method of treating a crude olefin oligomer with anhydrous ammonia and further washing with an alkali hydroxide aqueous solution is French Patent 21.
It is disclosed in Japanese Patent No. 14114.

This method can prevent the gelatinous precipitation of aluminum hydroxide and the formation of chlorinated hydrocarbons, but in the separation step, an insoluble suspension of nickel compounds is formed at the interface between the olefin oligomer and the alkaline aqueous solution, and It is also not possible to remove the soluble nickel complex.

Therefore, the above method cannot sufficiently purify the olefin oligomer.

An object of the present invention is to provide a method for purifying an olefin oligomer, that is, a method for removing an aluminum compound, a chlorine compound, and particularly a nickel compound remaining in a crude olefin oligomer produced by a dimerization and / or codimerization reaction of a monoolefin. It is in.

The present invention relates to a crude olefin oligomer obtained by subjecting a lower olefin to a dimerization and / or codimerization reaction in the presence of the above-mentioned organoaluminum chloride catalyst. First treated with anhydrous ammonia b. Next, in the treatment with an aqueous alkali hydroxide solution, the crude olefin oligomer is treated with oxygen or an oxygen-containing gas before and / or after step a.

The present invention can solve the above-mentioned various problems. In particular, the nickel complex remaining dissolved in the olefin oligomer disappears, and the formation of insoluble colloidal metallic nickel can be prevented.

By the above treatment, the nickel compound becomes a substance insoluble in the olefin oligomer and is easily separated from the olefin oligomer. This material appears to consist of nickel-aluminum hydroxide.

In the above treatment, the molar ratio of oxygen and nickel compound is set to 0.
It can vary from 1: 1 to 10: 1, but preferably 0.2: 1 to 2: 1. It is possible to use only oxygen, but it is also preferable to use a mixture of oxygen and an inert gas, for example a mixture of nitrogen and oxygen, or only air, or a mixture of air and nitrogen.

The oxygen concentration in the mixed gas is 2 to 30% by volume.

The contact time between the crude olefin oligomer and the oxygen-containing gas is
For example, 0.1 seconds to 10 minutes, preferably 0.1 seconds to
Ten seconds gives the best results between 0.1 and 5 seconds.

In the process described above, anhydrous ammonia is added in liquid or gaseous form.

The amount of anhydrous ammonia used is such that the molar ratio of ammonia to chlorine is 1: 1 to 10: 1, and preferably 1: 1 to all chlorine compounds present in the crude olefin oligomer.
3: 1 gives the best results 1.5: 1 to 2:
It is 1.

The contact time between the crude olefin oligomer and anhydrous ammonia is, for example, 0.1 seconds to 10 minutes, and preferably 0.1.
Seconds to 10 seconds, 0.1 seconds to 5 gives the best results
Seconds.

The olefin oligomer obtained by the above-mentioned anhydrous ammonia treatment is then washed, preferably with a 10 to 25% aqueous alkali hydroxide solution.

The volume ratio of the anhydrous ammonia-treated olefin oligomer to the alkali hydroxide aqueous solution is 100: 1 to 1: 1 and preferably 40: 1 to 1: 1.

When the crude olefin oligomer is treated first with oxygen or an oxygen-containing gas, then with anhydrous ammonia, and finally with an aqueous alkali hydroxide solution, about 1 by weight in the olefin oligomer.
-10 ppm of nickel remains regardless of contact time.

As one of the specific examples of the present invention, when the primary oxygen treatment before the anhydrous ammonia treatment is performed and the secondary oxygen treatment is performed after or during the alkaline hydroxide aqueous solution treatment, the residual nickel amount is 1 ppm by weight. It became the following.

The above-mentioned secondary oxygen treatment is also preferably performed under the same conditions as the primary oxygen treatment.

That is, the oxygen-containing gas is added at a molar ratio of oxygen to nickel compound of 0.1: 1 to 10: 1.

In the above treatment, even if oxygen or oxygen-containing gas is not introduced before anhydrous ammonia treatment and treated with oxygen or oxygen-containing gas before or at the same time as alkali hydroxide aqueous solution treatment, the nickel dissolved in the olefin oligomer is by weight. 1p
It was below pm.

Further, in the above treatment step, when oxygen or an oxygen-containing gas was not used, nickel dissolved in the olefin oligomer was 5 to 10 ppm by weight.

It is often the case that the anhydrous ammonia-treated olefin oligomer, the alkali hydroxide aqueous solution and the oxygen-containing gas are simultaneously contacted.

The contact time is 0.1 seconds to about 10 minutes, preferably 0.1 seconds to 10 seconds, with 0.1 seconds to 5 seconds giving the best results.

The above treatment is carried out at a temperature of 0 to 100 ° C., but for practical reasons, the same temperature as the dimerization and / or codimerization reaction is preferable. For example, the temperature is 20 to 80 ° C, and the most preferable temperature is 30 to 60 ° C.

The treatment pressure needs to be a pressure at which the crude olefin oligomer exists as a liquid phase, but a pressure of 0.1 to 5 kg / cm ² is sufficient.

After the above series of treatments, the treatment mixture is separated into a gas phase, an alkaline aqueous solution phase and a treated olefin oligomer phase.

The majority of the gas phase is an inert gas (eg nitrogen) and is released out of the system if depressurization is needed.

The alkaline aqueous solution separated from the olefin oligomer is
It is reused in step b or another step as necessary.

The olefin oligomer is washed with water and then sent to a rectification column to separate the target product.

The insoluble nickel-aluminum hydroxide is separated from the aqueous alkali solution by a conventional method such as filtration or decantation.

The present invention can be carried out by a batch method or a continuous method similarly to the dimerization and / or codimerization reaction.

Next, the present invention will be described with reference to Examples 1 to 4, but these do not limit the scope of the present invention. Example 5 is
This is a comparative example and is not included in the present invention.

Example 1 A transparent orange-brown solution obtained by carrying out a dimerization reaction of propylene using a catalyst produced from 1 mM of nickel octylate and ethylaluminum dichloride is treated under atmospheric pressure (about 0.1 kg / cm ² G). The following series of treatments was performed with vigorous stirring at 35 ° C.

． 120 ml of air containing about 1 mM oxygen. About 42 mM anhydrous gaseous ammonia 1. 50 ml of 18 wt% sodium hydroxide aqueous solution and 50 ml of air The contact time in each step is 1 minute.

After the above treatment is completed, the treatment mixture is separated into each phase. The insoluble inorganic compound precipitate is discarded and the gas phase is depressurized. No solid was observed at the interface between the crude hexene and the alkaline aqueous solution.

The crude hexene did not contain any inorganic compound, and the analysis result showed that the contents of nickel, aluminum and chlorine were each 1 ppm or less by weight.

Example 2 The reaction was carried out in the same manner as in Example 1, the primary air treatment was carried out, the ammonia treatment was carried out, the treatment was further carried out with an aqueous sodium hydroxide solution, and the secondary air treatment was carried out. Crude hexene after treatment with aqueous sodium hydroxide was slightly orange, indicating the presence of nickel. After the air treatment, the crude hexene was pale yellow, no inorganic compound was present, and the analysis result showed that the contents of nickel, aluminum, and chlorine were each 1 ppm or less by weight.

Example 3 Treated as in Example 1, but omitting the first air treatment, a small amount of nickel was found as a fluffy black solid at the interface between the crude hexene and the aqueous alkaline solution.
This solid could not be easily removed from the crude hexene. Dissolved nickel in crude hexene was analyzed to have a weight of 1 pp
It was m or less. The aluminum and chlorine contents were also at the same level.

Example 4 Treated as in Example 1 or 2, but without the final air treatment, a small amount of nickel was present as green nickel-aluminium hydroxide at the interface of crude hexene and aqueous alkaline solution. .

The crude hexene had a light orange color, and as a result of analysis, dissolved nickel was present in an amount of 3 ppm by weight. The content of aluminum and chlorine was 1 ppm or less by weight.

Example 5 When reacted in the same manner as in Example 1 and without oxygen or oxygen-containing gas treatment, the crude hexene after a series of treatments showed a pale orange color, and 5 ppm by weight of nickel was present.

Claims (11)

[Claims] 1. A nickel carboxylate represented by organochlorinated aluminum and a hydrocarbon-soluble (RCOO) ₂ Ni [where R is a hydrocarbon group] in the presence of a catalyst,
A crude olefin oligomer produced in the dimerization and / or codimerization reaction of a monoolefin of 2 to 4 carbon atoms, a. Anhydrous ammonia treatment step, b. Alkaline hydroxide aqueous solution treatment step, and c. In the method of removing aluminum, nickel and chlorine compounds in the olefin oligomer, a series of treatments including separation of the reusable aqueous alkali solution and recovery of the treated olefin oligomer in step b is carried out. A method for removing aluminum, nickel and chlorine compounds from an olefin oligomer, characterized by treating with oxygen or an oxygen-containing gas before and / or after. 2. The removal method according to claim 1, wherein the crude olefin oligomer is treated with oxygen or an oxygen-containing gas before the step a and simultaneously with the step b. 3. The removal method according to claim 1, wherein the crude olefin oligomer is treated with oxygen or an oxygen-containing gas in the middle of steps a and b. 4. The removal method according to claim 1, wherein a gas containing oxygen of 2 to 30% by volume is used. 5. The removing method according to claim 1, wherein nitrogen-diluted air is used. 6. The molar ratio of oxygen to nickel compound is 0.1:
Claim 1 characterized in that it is 1 to 10: 1
Item 5. The removal method according to any one of items 5 to 5. 7. The molar ratio of oxygen to nickel compound is 0.2:
It is 1-2: 1, The removal method of Claim 6 characterized by the above-mentioned. 8. In step a, gaseous or liquid anhydrous ammonia is added in a molar ratio of ammonia to chlorine compound of 1: 1 to 1.
Claim 1 characterized in that it is used at 10: 1.
Item 8. The removing method according to any one of items 7 to 7. 9. The method according to any one of claims 1 to 8, wherein in step b, the alkali hydroxide aqueous solution used is a 10 to 25 wt% sodium hydroxide aqueous solution. The described removal method. 10. A volume ratio of anhydrous ammonia-treated olefin oligomer and alkali hydroxide aqueous solution is 40: 1 to 1: 1.
The removal method according to any one of claims 1 to 9, wherein: 11. The processing temperature is 20 to 80 ° C., the process pressure is 0.1kg ^/ cm 2 ~5kg ^/ first term claims to it, characterized in cm from ² to 10 any one claim wherein Removal method.