JPH0329767B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The subject of the present invention is an improved process for the dimerization of ethylene to 1-butene.

Prior Art and its Problems In U.S. Pat. No. 2,943,125, Ziegler, K. describes the conversion of ethylene to 1-butene using a catalyst obtained by a mixture of trialkylaluminium and titanium or zirconium tetraalcoholates. The dimerization method is described. During this reaction, too, considerable amounts of high molecular weight polyethylene are formed which are completely unusable. Several improved methods have been proposed to reduce the polymerization rate. Especially US patent no.
No. 3,686,350 recommends the use of organic compounds of phosphorus with components of the catalyst, and U.S. Pat. No. 4,101,600 claims treatment of the catalyst with hydrogen, or
No. 3,879,485 claims the use of various ethers as solvents for the reaction medium. These modifications of the original catalyst system have resulted in substantial improvements in the selectivity of the reaction, especially in industries where the 1-butene must be able to be separated from the solvent leaving only traces of polar compounds in the butene. It can be seen that this method is hardly practical.

The aim of the present invention is to describe catalysts which exhibit particularly good activity and selectivity.

Means for Solving the Problems The present invention relates to an improved method for converting ethylene to 1-butene, the method comprising contacting ethylene with a catalyst obtained by the interaction of an alkyl titanate and an alkyl aluminum compound. , the catalyst converts a preformed mixture of alkyl titanate and ether in an ether/titanate molar ratio of 0.5:1 to 10:1 into a compound of the formula AlR ₃ or AlR ₂ H (wherein the residue R Each of these is an alkyl group).

Therefore, the ethers are used in a molar ratio of 0.5 to 10, preferably 1 to 3, more specifically 2 moles of ether, per mole of titanium compound. A-
Although there is no theoretical support for it, it can be assumed that the tel is complexed to the titanium atom, allowing titanium to undergo hexacoordination without other than autoassociation. If ether is used in a ratio of more than 10, for example 20 or more, or if it is used as a reaction solvent, the reaction will be very slow and its selectivity will be less It can be seen that in some cases no reaction occurs at all.

The aluminum compound used to prepare the catalyst has the general formula AlR ₃ or AlR ₂ H, where R
is preferably an alkyl group having 2 to 6 carbon atoms, such as triethylaluminum, tripropylaluminum, triisobutylaluminum, diisobutylaluminum hydride, trihexylaluminum.

The ethers used in this invention may be monoethers or polyethers. For example, diethyl ether, diisopropyl ether, diptyle ether, methyl tertiary butyl ether, tetrahydrofuran, 1,4-dioxane, dihydropyran, and ethylene glycol dimethyl ether may be used.

Exceptional results were obtained using tetrahydrofuran and/or 1,4-dioxane.

The alkyl titanates used in this invention have the general formula Ti(OR') ₄ , where R' is preferably 2 to
straight-chain or branched alkyl group having 8 carbon atoms). For example, tetraethyl titanate, tetraisopropyl titanate, tetra-n-butyl titanate, tetra-
2-Ethyl-hexyl titanate may also be used.

The catalyst components may be contacted in carbon hydrogen and/or one or more oligomerization products such as hexene, preferably in the presence of ethylene. The molar ratio between the aluminum compound and the titanium compound is about 1:1 to 20:1, preferably about 2:
The ratio is 1 to 5:1. The titanium concentration in the solution prepared in this way is advantageously between 10 ^-4 and 1
0.5 mol, preferably 2×10 ⁻³ to 0.1 mol per portion. The temperature at which the catalyst is prepared is usually -10
~+80°C, preferably -10~+45°C, more preferably 0~+40°C. When ethylene is present in the solvent, the amount preferably corresponds to saturation of the solution at the temperature in question and at a pressure selected from atmospheric pressure or above.

The catalyst solution thus obtained may be used as it is, or may be diluted by adding a reaction product.

The ethylene dimerization reaction may be carried out at 20 to 150°C, preferably 20 to 70°C, more preferably 50 to 70°C. The pressure is preferably 0.5-8 MPa.

In a particular method using a discontinuous catalytic dimerization reaction, a selected volume of the catalyst solution prepared as described above is introduced into a reactor equipped with the usual equipment for stirring and cooling. Then preferably 0.5~
Pressurize with ethylene at a pressure of 8 MPa and reduce the temperature to 20
Maintain at ~70°C, preferably 50-70°C. Ethylene is fed to the reactor at constant pressure until the total volume of liquid produced represents 2 to 50 times the volume of catalyst initially introduced. The catalyst is then destroyed, for example by adding water. The reaction products and optionally the solvent are then removed and separated.

In the case of continuous operation, it is preferably carried out as follows. The catalyst solution is injected simultaneously with the ethylene into the stirred reactor in a conventional manner or by external recirculation. Reduce the temperature to about 20~70℃, preferably 50~
Maintain at 70°C. The pressure is preferably 0.5-8 MPa. A portion of the reaction mixture flows through a pressure reducing valve which maintains the pressure constant, with a mass flow rate equal to the mass flow rate of the fluid introduced. The fluid thus reduced in pressure is sent to a distillation column apparatus. With this device,
1-Butene can be separated from ethylene on the one hand. This ethylene is sent back to the reactor. On the other hand, 1-butene can be separated from hexene and octene. A portion of these is sent back to the catalyst preparation section. The column components containing catalyst and heavy products may be incinerated or the recovered catalyst may be recycled.

In a preferred method of implementation, the catalyst components are mixed under an ethylene atmosphere at a temperature of -10 to +45°C.
The temperature is then raised to 50-70°C to continue the dimerization reaction. More preferably, the mixed components of the catalyst are maintained at a temperature of -10 to +45°C for 30 seconds to 24 hours, after which the temperature is increased to 50 to 70°C.

<Effects of the Invention> Since the present invention is configured as described above, the following effects are achieved.

The catalyst used in the present invention exhibits particularly excellent activity and selectivity. This effect is more pronounced than that produced by previously claimed coordinating substances such as phosphites or amines, and when the ethers are used in amounts comparable to their use as solvents. or more pronounced than the effect produced by ethers when added after mixing the hydrocarbyl aluminum and the alkyl titanate. This method also
It also shows the advantage of obviating the use of these ethers as solvents, the disadvantages of which are noted, among other things, the difficulty of separation. This method even makes it possible to avoid using external solvents. The components of the catalyst can be mixed directly in one of the products or by-products of the reaction. This avoids the consumption or recycling of said solvent, which is always difficult to separate from the mixture resulting from oligomerization.

EXAMPLES The following examples illustrate the invention but do not limit its scope.

Example 1 The following are introduced in sequence under an ethylene atmosphere into a 250 ml stainless steel Grignard autoclave equipped with a double jacket whose temperature can be adjusted to 18° C. by water circulation. 2.5 ml of a solution of triethyl aluminum in hexene fraction prepared by mixing 0.25 ml of triethyl aluminum and 9.75 ml of hexane, followed by 0.05 ml of tetra-n-butyl titanate and 0.024 ml of tetrahydrofuran.
ml of tetra-n-butyl-tetrahydrofuran titanate complex solution prepared by mixing with 2.42 ml of hexene fraction. The molar ratio between tetrahydrofuran and titanate is 2.1:1. After 2 minutes of interaction, the temperature is increased to 55° C. and the ethylene pressure is increased to 2 MPa.

After 2.5 hours of reaction, the introduction of ethylene is stopped and the catalyst is destroyed by injection of 2 ml of pressurized sewage water. A total of 133g of ethylene was consumed.

In addition to unreacted ethylene, n-butane
0.28 g, 1-butene, 92.40 g, hexene, 6.46 g, octene, 0.17 g, and polyethylene, 0.0027 g. Analysis of the _C4 fraction by gas chromatography using a flame ionization detector shows a total 2-butene content of less than 10 ppm. Polyethylene shows 27ppm.

Under these conditions, the productivity of the catalyst is 1
It rises to 13088 g of 1-butene per g.

Example 2 (comparative example - not part of the invention) In the same equipment used in Example 1, the amount of tetrahydrofuran introduced was increased so that the molar ratio of tetrahydrofuran to titanate was changed to 2.1:1 instead of 2.1:1.
The ratio was set to 20:1, and all other conditions were as in Example 1.
I made it the same as After 5 hours at 55°C no conversion of ethylene was observed.

Example 3 (comparative example - not part of the invention) Same equipment as used in example 1, introducing more than twice as much titanium compound, more than twice as much aluminum compound, and no tetrahydrofuran. The other conditions were the same as in Example 1, and 91.6 g of 1-butene, 0.28 g of butane, 11.8 g of hexene, 0.68 g of octene, and 0.1 g of polyethylene were obtained. 1
-Butene contains 360 ppm of 2-butene. The productivity of the catalyst is only 6,500 g of butene per gram of titanium metal.

Example 4 (Comparative Example - Not Part of the Invention) Hexene fraction prepared by mixing 0.25 ml of triethylaluminum and 9.75 ml of hexene in the same apparatus used in Example 1 under an ethylene atmosphere. 2.5ml of triethylaluminum solution, then 0.024ml of tetrahydrofuran, and finally hexene distillate.
Tetra-n-butyl titanate 0.05 in 2.42ml
ml solution is introduced sequentially.

The reaction was then carried out under the same conditions as in Example 1 and following the same procedure as described in Example 1.

The productivity of the catalyst is only 5592 g of 1-butene per gram of titanium metal. Polyethylene is 70ppm.

Example 5 (Comparative Example - Not Part of the Invention) Into the same apparatus used in Example 1, the following are introduced sequentially under an ethylene atmosphere. 2.5 ml of triethyl aluminum solution in hexene fraction prepared by mixing 0.25 ml of triethyl aluminum and 9.75 ml of hexene, then 0.05 ml of tetra-n-butyl titanate solution in 2.42 ml of hexene fraction;
Finally, add 0.024ml of tetrahydrofuran.

The reaction is then carried out under the same conditions as in Example 1 and according to the same procedure as described in Example 1.

The productivity of the catalyst is only 9231 g of 1-butene per gram of titanium metal. Polyethylene shows 42ppm.

Example 6 Into the same apparatus as in Example 1, the following are introduced in sequence under an ethylene atmosphere and the temperature maintained at 18°C.
Triethyl aluminum 0.25ml and hexene 9.75ml
2.5 ml of triethylaluminum solution in hexene fraction prepared by mixing, then 0.05 ml of tetra-n-butyl titanate and 1,4-dioxane.
A solution of tetra-n-butyl-1,4-dioxane titanate complex prepared by mixing 0.25 ml and 2.42 ml of hexene fraction. The molar ratio of 1,4-dioxane to titanate is 2.07:1. After 2 minutes of interaction, the temperature was brought to 55°C and the ethylene pressure was increased.
Set it to 2MPa.

After 2.5 hours of reaction, the reaction was stopped by introducing 2 ml of water under pressure. A total of 120g of ethylene was consumed.

In addition to the unreacted ethylene, the following are recovered. n-butane 0.18g, 1-butene 87.09g,
6.88g hexene, 0.20g octene and 0.0042g polyethylene. The _C4 cut contains 2060 ppm butane with a total 2-butene content of less than 10 ppm. Polyethylene represents 45ppm.

The productivity of the catalyst reaches 12,336 g of 1-butene per 1 g of titanium metal.

Example 7 Into the same apparatus as in Example 1, the following items were sequentially introduced under an ethylene atmosphere while maintaining the temperature at 18°C. Triethyl aluminum 0.5ml and hexene
1.25 ml of a solution of triethylaluminum in hexene fraction prepared by mixing 9.5 ml of n-
A solution of n-butyl-glyme (ethylene glycol dimethyl ether) titanate complex prepared by mixing 0.05 ml of butyl titanate with 0.05 ml of glyme and 2.5 ml of hexene fraction. The molar ratio of n-butyl-glyme to titanate is 3.2:1.

After 2 minutes of interaction, the temperature is brought to 55° C. and the ethylene pressure is brought to 2 MPa.

After 2 hours of reaction, the catalyst is destroyed by adding 2 ml of water under pressure. A total of 136g of ethylene was consumed.

In addition to the unreacted ethylene, the following are recovered. n-butane 0.22g, 1-butene 89.28
g, hexene 9.83 g, octene 0.41 g and polyethylene 0.0139 g. _C4 fraction is n-butane 2400ppm
and a total 2-butene content of 10 ppm or less. Polyethylene shows 139ppm.

The productivity of the catalyst reaches 12,646 g of 1-butene per gram of titanium metal.

Example 8 (comparative example - not part of the invention) In the same equipment as in example 5, the n-butyl-
The amount of glyme is determined by the molar ratio of glyme to titanate.
The ratio was increased to 230:1 instead of 3.2:1, and all other aspects were the same as in Example 5.

The productivity of the catalyst is then only 1350 g of 1-butene per gram of titanium metal.

Example 9 Into the same apparatus as in Example 1, the following are introduced in sequence under an ethylene atmosphere and the temperature maintained at 18°C. Triethyl aluminum 0.5ml and hexene
2.5 ml of a solution of triethylaluminum in hexene fraction prepared by mixing 19.5 ml of n-butyl-dihydropyran, then 0.4 ml of n-butyl titanate and 0.215 ml of dihydropyran in 19.6 ml of hexene.・Titanate complex solution 2.5
ml. The molar ratio of dihydropyran to titanium is 2:1.

After 2 minutes of interaction, the temperature is brought to 55° C. and the ethylene pressure is brought to 2 MPa.

The catalyst is destroyed after one and a half hours of reaction.

The recovered product is 1-g per gram of titanium metal.
This corresponds to a catalyst productivity of 6146 g of butene.

Example 10 Into the same apparatus as in Example 1, under an ethylene atmosphere and maintaining the temperature at 35°C, the following are introduced in sequence: Triethylaluminum 0.5ml and heptane
2.5 ml of triethylaluminum solution in heptane prepared by mixing 19.5 ml of heptane, then 19.4 ml of heptane
0.34 ml of isopropyl titanate and 1,4 in ml
- 2.5 ml of a solution of isopropyl-1,4-dioxane titanate complex prepared by mixing with 0.2 ml of dioxane. The molar ratio of dioxane to titanate is 2:1.

After 5 minutes of interaction, the temperature was brought to 70° C. and the ethylene pressure was brought to 3 MPa. The catalyst was destroyed after 2 hours of reaction.

The productivity of the catalyst is 8500 g of 1-butene per 1 g of titanium metal.

Claims (1)

[Scope of Claims] 1. An improved method for converting ethylene to 1-butene, comprising contacting ethylene with a catalyst obtained by the interaction of an alkyl titanate and an alkyl aluminum compound, the method comprising: However, the molar ratio of ether/titanate is from 0.5:1 to
A preformed mixture of 10:1 alkyl titanate and ether is allowed to interact with an aluminum compound represented by AlR ₃ or AlR ₂ H, where each residue R is an alkyl group. A method characterized in that it is obtained by 2. Claim 1, wherein the molar ratio of ether to alkyl titanate is about 1:1 to 3:1.
The method described in section. 3. A method according to claim 1 or 2, wherein the interaction is carried out in a solvent consisting of hexane recovered as a by-product of the reaction. 4. Claim 1, wherein the ether is diethyl ether, diisopropyl ether, dibutyl ether, methyl tert-butyl ether, tetrahydrofuran, 1,4-dioxane, dihydropyran, or ethylene glycol dimethyl ether.
The method according to any one of 3 to 3. 5. The method according to claim 4, wherein the ether is 1,4-dioxane. 6. The method according to claim 4, wherein the ether is tetrahydrofuran. 7 The interaction of a preformed mixture of alkyl titanate and ether with an aluminum compound is carried out under an ethylene atmosphere at a temperature of -10 to +45°C, and upon heating the ethylene is converted to 1-butene. 7. A method according to any one of claims 1 to 6, wherein the temperature is 50 to 70<0>C. 8. Maintaining the mixed components of the catalyst at a temperature of -10 to +45 °C for 30 seconds to 24 hours, then increasing the temperature to 50 to 70 °C,
The method according to claim 7. 9. The molar ratio between the aluminum compound and the titanium compound is 1:1 to 20:1, the titanium concentration is 10 ^-4 to 0.5 mol per liter when using a catalyst, and 20
9. A process according to any one of claims 1 to 8, characterized in that ethylene is converted to 1-butene at a temperature of ~150<0>C and under a pressure of 0.5 to 8 MPa. 10. The method according to claim 9, wherein the temperature is 20 to 70°C.