Use of a complex catalyst in the synthesis of polyalphaolefins

Abstract

The application discloses a complex catalyst and application thereof in synthesis of poly-alpha-olefin, wherein the complex catalyst is composed of a main catalyst AlCl3 and a Lewis acid electron donor, and the chemical structural formula of the Lewis acid electron donor is R-S-H, wherein R is selected from an alkyl group, a cycloalkyl group, an aromatic hydrocarbon group or an olefin group. When the complex catalyst is used in synthesis of poly-alpha-olefin synthetic oil, the complex catalyst has the advantages of high activity, mild and controllable reaction process, high reaction activity, low pour point of the product and the like, and therefore has a good application prospect.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of catalysts, and particularly relates to a complex catalyst and application thereof in synthesis of poly-alpha-olefin (PAO). BACKGROUND

[0002] In recent years, with the upgrading speed of lubricating oil becoming faster and faster, the market demand for high-end lubricating oil products has driven the rapid growth of the demand for poly-alpha-olefin (PAO) base oil. Compared with mineral oil, PAO synthetic oil has better oxidation stability and viscosity-temperature performance, high viscosity index, low pour point, good additive performance, and can be mixed with mineral oil at any ratio. Due to the excellent physical and chemical properties of PAO, it has been widely used in the fields of aviation, military industry, high-grade automobiles, etc.

[0003] At present, the global PAO base oil production capacity is relatively concentrated, and the top three producers, INEOS, ExxonMobil and Chevron, account for more than 90% of the global production capacity. The catalysts used for synthesizing PAO mainly include AlCl3, BF3, metallocene and ionic liquid catalysts, etc. Due to the low cost and mild reaction conditions of AlCl3 catalyst, it is still the mainstream PAO catalyst in China.

[0004] Chevron's patent US 8115040B2 discloses a method of synthesizing PAO with AlCl3 as catalyst, which process adds a small amount of HCl as promoter, the product has a pour point of less than -50℃, and a viscosity index of at least 134. Chevron's patent US 8178739B2 discloses a method of synthesizing PAO with AlCl3 as catalyst, which patent produces base oil with kinematic viscosity of 20 to 90 by adjusting the oligomerization step. East China University of Technology's patent CN 104250564A discloses a mixture of AlCl3 and TiCl4 as catalyst for the industrial production of poly-alpha-olefin lubricating oil base oil from coal wax cracking olefins. Exxon's patents CN 101977879A, CN 105925340A disclose a method for preparing oligomeric poly-alpha-olefins, which includes oligomerizing low molecular weight PAO oligomers in the presence of a Lewis acid catalyst such as promoted AlCl3 or BF3 under oligomerization conditions. The low molecular weight PAO oligomers used as feed or feed components for the method are light olefinic byproduct fractions containing dimers and light fractions derived from a metallocene-catalyzed PAO oligomerization process, which have a molecular weight of 150-600 and a terminal olefin (vinylidene) content of at least 25%. Patents US 12261388, US 12538746 use AlCl3 as catalyst to obtain a series of base oil products with a viscosity index of up to 145 and a pour point of -54℃ at the lowest. AlCl3 is also used in ionic liquid catalyst systems, patent US 8222471B2 uses olefins with boiling points below 82℃ to obtain lubricating oil base oil with kinematic viscosity greater than 1100 mm 2 / s at 40℃; patent US 12763866 uses AlCl3 and 1-butylpyridinium chloride to prepare an ionic liquid catalyst, which produces lubricating oil synthetic oil with a viscosity index of no less than 134 and a pour point of no higher than -28℃ by way of alkylating oligomerized olefins.

[0005] However, due to the strong acidity of aluminum chloride, some patents or documents disclose adding water or alcohol complexes to aluminum chloride to adjust the acidity of aluminum chloride. Patent CN 110668908A discloses 2-ethylhexanol as a complex of aluminum chloride, which can improve the yield of low viscosity oil. Patent CN 101977879A discloses the synthesis of PAO using water and lower alcohols as proton promoters for catalysts. Zhubo Yu (Zhubo Yu, Research on the Synthesis of Lubricating Oil Base Oil from 1-Decene by Heterogeneous Polymerization) detailed the effect of adding water to the 1-decene synthesis of PAO with aluminum chloride catalyst.

[0006] According to a large number of disclosed patents or reports, since AlCl3 is strongly acidic, the viscosity of the product is too high, and the production process is difficult to control. After adding an appropriate amount of complex, it can synergistically provide active protons, activate the raw material alpha-olefin, and make it generate more regular branched PAO. The pour point of the product is lower than that obtained by using AlCl3 as a catalyst alone, and the 100-degree kinematic viscosity is also lower. However, most of the current complexes are water, and the reaction is more violent than using AlCl3 alone as a catalyst, and the production process is difficult to control. After replacing water with low alcohols such as ethanol, butanol, etc. as a complex, the reaction can be significantly reduced in intensity, but the ability to provide protons is also significantly reduced, and the pour point and 100-degree kinematic viscosity of the product are higher. SUMMARY

[0007] In order to solve the above technical problems, the application provides a complex catalyst composed of AlCl3 and Lewis acid electron donor. When the catalyst is used for synthesizing poly-alpha-olefin synthetic oil, it has the advantages of high activity, mild and controllable reaction process, high reaction activity, and low product pour point.

[0008] In order to achieve the above object, the application adopts the following technical scheme:

[0009] A complex catalyst composed of a main catalyst AlCl3 and a Lewis acid electron donor.

[0010] Further, the chemical structural formula of the Lewis acid electron donor is R-S-H, wherein R is selected from alkyl, cycloalkyl, aromatic hydrocarbon or olefin group.

[0011] Further, the molar ratio of the Lewis acid electron donor to the main catalyst in the complex catalyst is 0.001-1.

[0012] The complex catalyst can be used in the synthesis of poly-alpha-olefin, and the application method is specifically mixing the complex catalyst with the raw material in an inert solvent and then reacting under stirring.

[0013] Further, the inert solvent is any one of hexane, cyclohexane, methylcyclohexane and 1,2-dichloroethane.

[0014] Further, the mass ratio of the complex catalyst to the raw material is 0.001-5.

[0015] Further, the raw material is a mixture of any two or three of 1-octene, 1-decene and 1-dodecene.

[0016] Further, the temperature of the reaction is 30-150℃, and the time is 0.1-10h.

[0017] The significant advantages of the application are:

[0018] The present application uses a thiol compound with a mercapto group as a complex of AlCl3 catalyst to co-catalyze the polymerization of an alpha-olefin into PAO. The sulfur atom on the mercapto group has a larger radius than the oxygen atom, belongs to a soft acid, and has a smaller binding force on the hydrogen atom, easily releases hydrogen, resulting in the acidity of the thiol being stronger than that of alcohol, and having more active catalytic performance than ethanol in the process of acting with aluminum chloride. Therefore, the method has the following advantages:

[0019] (1) The acidity of AlCl3 can be appropriately adjusted, and a suitable amount of protons is provided for the reaction, which can prevent the deactivation of aluminum chloride due to excessive alcoholysis;

[0020] (2) The heat release is small during the synthesis of PAO, the reaction is mild and easy to control, the product yield is high, and it is conducive to industrial production;

[0021] (3) Low-viscosity PAO with low pour point and 100-degree kinetic viscosity can be obtained, which meets the current market demand;

[0022] (4) The catalyst cost is low. DETAILED DESCRIPTION

[0023] A complex catalyst is composed of a Lewis acid electron donor R-S-H and a main catalyst AlCl3 in a molar ratio of 0.001-1. Wherein, R is selected from alkyl, cycloalkyl, aromatic hydrocarbon or olefin group.

[0024] The application method of the complex catalyst in the synthesis of poly-alpha-olefin is to sequentially inject inert solvent, complex catalyst into the reactor, and then add raw materials, and react at 30-150 ℃ for 0.1-10 h under stirring.

[0025] The inert solvent is any one of hexane, cyclohexane, methylcyclohexane and 1,2-dichloroethane.

[0026] The mass ratio of the complex catalyst to the raw materials is 0.001-5.

[0027] The raw material is a mixture of any two or three of 1-octene, 1-decene and 1-dodecene.

[0028] In order to make the content of the present application more convenient to understand, the technical solutions of the present application will be further described in combination with specific embodiments, but the present application is not limited thereto.

[0029] Example 1:

[0030] The poly-alpha-olefin synthesis experiment was carried out in a three-necked flask, and the specific operation was as follows:

[0031] 1) Take out the three-necked flask and rotor which have been dried in advance, and connect the heat coupling, condenser and stopper to the three necks respectively. Weigh the required raw materials, solvents and catalyst components in the glove box. Turn on the vacuum pump, and switch the double-tube to the vacuum position. Vacuumize the three-necked flask to room temperature. Turn on the nitrogen, and slowly adjust the double-tube to the nitrogen position, making sure to prevent back suction. Switch the vacuum-nitrogen environment for three times, and finally keep the device in a nitrogen environment. Turn on the stirring, open the condenser water, and set the heating to 70°C. Inject 40 ml of cyclohexane into the three-necked flask through the stopper. Increase the temperature to 50°C, and quickly take out the stopper. Pour 1.2 g of AlCl3 powder into the flask, and inject 0.28 g of ethanethiol diluted with cyclohexane in advance through the syringe. Increase the temperature to 70°C, and inject 80 ml of 1-decene through the syringe. Switch the three-way valve on the condenser to the three-way position, and adjust the nitrogen. React for 2 hours, and weigh the syringe and the weighing bottle.

[0032] 2) Add ultrapure water to the prepared sample, and magnetically stir for several minutes. Then, let the sample stand in the separatory funnel to separate the liquid, and collect the oil phase. Repeat the water washing for three times, and add 1 g of anhydrous sodium sulfate. Let the sample stand for several hours, and then remove the sodium sulfate solid by vacuum filtration. Distill the obtained oil product under reduced pressure at 180°C until no liquid droplets appear on the condenser wall. Weigh the obtained product, test the viscosity and pour point, and calculate the yield. The data results are shown in Table 1.

[0033] Example 2:

[0034] Replace the used ethanethiol with an equal molar amount of butanethiol, and the other operations are the same as in Example 1.

[0035] Example 3:

[0036] Replace the used ethanethiol with an equal molar amount of 1-propanethiol, and the other operations are the same as in Example 1.

[0037] Example 4:

[0038] Replace the used cyclohexane with an equal volume of methylcyclohexane, and the other operations are the same as in Example 1.

[0039] Example 5:

[0040] Modify the reaction temperature to 110°C, and the other operations are the same as in Example 1.

[0041] Comparative Example 1:

[0042] Do not add ethanethiol, and the other operations are the same as in Example 1.

[0043] Comparative Example 2:

[0044] Replace the used ethanethiol with an equal molar amount of water, and the other operations are the same as in Example 1.

[0045] Comparative Example 3:

[0046] The ethanethiol used is replaced by an equal molar amount of ethanol, and the other operations are the same as in Example 1.

[0047] Table 1

[0048]

[0049] As can be seen from Table 1, the addition of Lewis acid electron donors can increase the product yield, reduce the kinematic viscosity and pour point, among which the effect of adding butanethiol is the best.

[0050] The above description is only the preferred embodiment of the present application, and any equivalent changes and modifications made within the scope of the patent application of the present application shall be covered by the scope of the present application.

Claims

1. Use of a complex catalyst in the synthesis of polyalpha-olefins, characterized in that, The complex catalyst is composed of a main catalyst AlCl3 and a Lewis acid electron donor, The chemical structural formula of the Lewis acid electron donor is R-S-H, wherein R is selected from an alkyl group, a cycloalkyl group, an aromatic hydrocarbon group or an olefin group. The application method is specifically that the complex catalyst is mixed with raw materials in an inert solvent, and then the reaction is carried out under stirring.

2. Use according to claim 1, characterized in that, The molar ratio of the Lewis acid electron donor to the main catalyst in the complex catalyst is 0.001-1.

3. Use according to claim 1, characterized in that, The inert solvent is any one of hexane, cyclohexane, methylcyclohexane and 1,2-dichloroethane.

4. Use according to claim 1, characterized in that, The mass ratio of the complex catalyst to the raw materials is 0.001-5.

5. Use according to claim 1 or 4, characterized in that, The raw materials are a mixture of any two or three of 1-octene, 1-decene and 1-dodecene.

6. Use according to claim 1, characterized in that, The reaction temperature is 30-150 ℃, and the reaction time is 0.1-10 h.

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