RU2209201C1 - Method for combined preparing linear alkyl- benzenes and synthetic oils - Google Patents

Abstract

FIELD: organic chemistry, petroleum chemistry, chemical technology. SUBSTANCE: method involves alkylation of benzene with alpha-olefins in the presence of catalytic complex based on aluminum chloride and the following separation of products of benzene alkylation to yield linear alkylbenzenes and synthetic oil. Mixture of individual olefins V₁₀ and C₁₂ taken in the mass ratio = 1 : (3-3.67) is used as olefins and process is carried out in the molar ratio aluminum chloride : alpha-olefins = (0.0044-0.037) : 1 and in the molar ratio benzene : alpha-olefins = (1-8.2) : 1 up to attainment mass ratio linear alkylbenzenes with molecular mass 234-242 Da : oil = 1 : (0.29-3.9). Fresh benzene or backward benzene or mixture of fresh and backward benzene from separation step of products of alkylation of benzene with alpha-olefins are used as benzene source taken in any ratio. Method provides simultaneous preparing C₁₀-C₁₂-linear alkylbenzenes satisfying to requirements imposed to raw used for production of detergents and synthetic oils with ignition temperature 190 C, not less, and broad range of kinematic viscosity 3.8-9.5 mm²/s/s at 100 C and solidification point 55 C, not above. EFFECT: improved preparing method. 3 cl, 1 tbl, 12 ex

Description

The invention relates to the production of alkylbenzenes, in particular to methods for the joint production of linear alkylbenzenes, which can be used to obtain detergents, and synthetic oils with a kinematic viscosity of 3.8-9.5 mm ² / s at 100 ^o C and pour point not higher than minus 55 ^o C, and which can be used as the basis of motor, transmission, refrigeration, vacuum oils, as well as components of semi-synthetic oils. According to the requirements for raw materials for the production of alkylbenzenesulfonates used in the production of surfactants, linear monoalkylbenzenes must have a molecular weight (m) of 234-242 and C ₁₀ -C ₁₂ carbon atoms in the alkyl chain.

A known method of producing linear alkylaromatic hydrocarbons (RF patent 2169134, С 07 С 2/66, 15/107, publ. 06/20/2001), containing 10-14 carbon atoms in the alkyl chain, including the following cycle of operations:
a) dehydrogenation of C ₁₀ -C ₁₄ n-paraffins to the corresponding n-olefins in a dehydrogenation reactor to obtain a mixture containing also diolefins and aromatic by-products, as well as light decomposition products and hydrogen; b) selective hydrogenation of the diolefins obtained in operation (a) to monoolefins, to obtain a mixture consisting essentially of monoolefins and n-paraffins in addition to the aromatic by-products obtained in operation (a); c) supplying the stream from step (b), together with the stream consisting of benzene, to an alkylation apparatus in which an alkylation catalyst selected from HF, AlCl ₃ or solid acidic catalysts (heterogeneous) is used, used in quantities of 0, 05-10 mol.% In relation to the olefin, and the molar ratio of aromatic hydrocarbon / olefin is from 1 to 20; g) the flow of paraffins to the hydrogenation operation; f) recycling the stream coming from operation (e) to the dehydrogenation apparatus of operation (a).

 The disadvantage of this process is the use of large quantities of catalyst, which is used in the range from 0.05 to 10 mol%. with respect to the olefin, in this case mainly linear alkylbenzenes are obtained.

A known method for producing synthetic oils, which includes 4 stages: 1) contacting 1-15 moles of aromatic hydrocarbons (benzene, toluene, xylene, ethylbenzene) with 1 mole of alpha-olefin C ₆ -C ₁₈ normal structure in the presence of 1-30 moles of HF when a temperature of 5-100 ^o C; 2) the allocation of a mixture of monoalkylaromatic hydrocarbons with alkyl radicals C ₆ -C ₁₈ ; 3) contacting 1-10 moles of monoalkyl aromatic hydrocarbons with 1 mole of alpha-olefin C ₆ -C ₁₈ in the presence of 2-10 moles of AlCl ₃ or AlBr ₃ at a temperature of 60-90 ^o C; 4) the allocation of dialkylaromatic hydrocarbons used as the basis of synthetic oil from the reaction mixture. The viscosity index of the obtained base -116-121, pour point minus 33 - minus 38 ^o With (US patent 4148834, With 07 3/52, publ. 04.10.79,).

The disadvantage of this method is its multi-stage nature, so, in the first stage, monoalkylbenzenes are obtained, which are isolated from the reaction mass in the second stage, and in the third stage they are contacted with alpha-olefins, resulting in dialkyl aromatic hydrocarbons used as the basis for synthetic oil, however the viscosity index of the obtained oil is very low, the pour point of these oils is minus 33-minus 38 ^o C, with the requirements for this indicator not higher than minus 55 ^o C.

A known method of preparing arylated polyolefins, which are used as base liquids or additives to lubricants (US Patent 6071864, C 07 C 2/66, publ. 06.06.2000). In the examples given in this patent, a mixture of alpha-olefins from C ₈ to C ₁₂ and benzene is used for the synthesis. The molar ratio of benzene: olefin oligomers is maintained equal to from 0.5: 1 to 8: 1. The reaction is carried out as follows: olefins and a catalyst (aluminum chloride) are loaded into the autoclave, the temperature is brought to 20-100 ^{° C.} , the reaction time is 1-16 hours, so that the alpha-olefins turn into dimers. At the same time, benzene is also pumped there.

The reaction products are cooled with a dilute alkali solution, washed with water and dried with sodium sulfate. The oily product is isolated by distillation in vacuo and 150 ^° C. In Example 17 (Table 6 of the patent description), experimental data are presented using a mixture of C ₈ -C ₁₂ alpha olefins. The molar ratio of benzene: olefins = 8: 1 0.88% by weight is used. catalyst, reaction temperature 40 ^{° C.} , reaction time 24 hours, oil yield 75%. Oil properties: kinematic viscosity at 100 ^{o C.} 4.87 mm ² / s, viscosity index 102, bromine number 1.5, pour point below minus 38 ^o C. The disadvantage of this method is that the process is aimed at obtaining one target product, however, it does not meet the requirements for multigrade synthetic engine oils.

The closest is a method of obtaining a base of low-cushioning synthetic motor oil (RF patent 2019560, IPC ⁷ C 10 M 105/06, publ. 09/15/94), according to which benzene is alkylated with C ₈ -C ₁₀ alpha-olefins at a temperature of 40- 60 ^o In the presence of a catalyst complex based on aluminum chloride. The process is carried out at molar ratios of benzene: alpha-olefins = 0.65-0.80: 1 and aluminum chloride: alpha-olefins = 0.0055-0.0110: 1. The resulting LABs are ~ 18%, and the base oil ~ 82 % of the reacted components, i.e. their ratio in the reaction products is 1: 4.5. LABs or monoalkylbenzenes with C ₈ -C ₁₀ alkyl substituents obtained by this method have an average molecular weight (MM) of 210, the base of the oil has a viscosity index of 125-127, pour point minus 57 ^o C, flash point 203-207 ^o C.

The disadvantage of this process is that the LABs obtained by this process do not meet the requirements for linear alkylbenzenes used for the production of detergents, since the molecular weight is much lower than that required in 234-242, due to the fact that the patented process is aimed only at obtaining the basis low-curing multigrade engine oil with a flash point of at least 200 ^o C and a kinematic viscosity of 6-7 mm ² / s at 100 ^o C.

The objective of the invention is the simultaneous production of C ₁₀ -C ₁₂ linear alkyl benzenes that meet the requirements for raw materials for the production of detergents, and synthetic oils with a flash point of at least 190 ^o With a wide range of kinematic viscosity of 3.8-9.5 mm ² / s at 100 ^o C and pour point not higher than minus 55 ^o C.

The problem is solved by alkylation of benzene with alpha olefins in the presence of a catalyst complex based on aluminum chloride, while a mixture of individual C ₁₀ and C ₁₂ olefins taken in a certain mass ratio = 1: 3-3.67 is used as olefins and the process is carried out at molar the ratios of benzene: alpha-olefins = 1-8,2: 1 to achieve a mass ratio of linear alkylbenzenes with m.m. 234-242: oil = 1: 0.29-3.9, and the process is carried out at a molar ratio AlCl ₃ : alpha olefins = 0.0044-0.037: 1, the reaction products are divided into two target products, while in the process you can use both fresh benzene and reflux benzene or a mixture of unreacted reflux benzene, which is isolated from the reaction products, with fresh in any ratio.

 When carrying out the process under the claimed conditions, the conversion of benzene is achieved 11.7-60.8%, olefins - 98-99.6%, the yield of olefins taken on LABs is 22.1-105.6%, and oil - 36.8 -86.8%. The process of alkylation of benzene with alpha-olefins to achieve the claimed mass ratio of LAB to m.m. 234-242: oil = 1: 0.29-3.9 allows you to simultaneously get two target products of a given quality.

In the claimed conditions receive linear alkylbenzenes containing 10-12 carbon atoms in the alkyl chain, with m.m. 234-242, suitable for use as raw materials in the production of detergents, and synthetic oil with a pour point not higher than minus 55 ^o C, a flash point not lower than 190 ^o C and a viscosity index of 119-148.

Distinctive features of the invention is the use as olefins of a mixture of individual olefins With ₁₀ and C ₁₂ taken in a mass ratio of 1: 3-3,67 and the alkylation process at a molar ratio of benzene: alpha-olefins = 1-8,2: 1 to obtain mass ratio of LAB with m.m. 234-242: oil = 1: 0.29-3.9.

The claimed invention meets the criterion of "novelty", since these distinguishing features are absent in the prototype, in addition, it meets the criterion of "inventive step", since none of these similar methods achieves the simultaneous production of two target products by alkylation of benzene with alpha-olefins in one stage - LABs with 10-12 carbon atoms in the side chain and a molecular weight of 234-242, suitable as raw materials for the production of detergents, and synthetic oils with a flash point not below 190 ^o C, pour point no higher than minus 55 ^o C and kinematic viscosity of 3.8-9.5 mm ² / s at 100 ^o C.

 "Industrial applicability" of the claimed invention is confirmed by the following examples.

Example 1
224.35 g / h of fresh benzene and 115.05 g / h of a mixture of C ₁₀ and C ₁₂ alpha olefins with an average molecular weight of 161, taken in a mass ratio of 1: 3.52, are continuously fed into the alkylation reactor. The molar ratio of benzene-olefins = 4: 1. 3.4 g / h of the catalyst complex containing 25% of the mass is fed into the same reactor. AlCl ₃ . The molar ratio of AlCl ₃ : olefins = 0.0088: 1. During the experiment (240 min), 460.2 g of a mixture of alpha-olefins, 807.4 g of benzene and 13.6 g of the catalyst complex are fed into the reactor. The degree of conversion of benzene is 23.0%, olefins 99.0%. After separation of the unreacted components from the reaction mass, 353.1 g of monoalkylbenzenes (LABs) and 72.2 g of the intermediate fraction are distilled from it. The remainder of 205.2 g is a synthetic oil. The ratio of the obtained LABs and oil = 1: 0.58.

Characteristics of the obtained LABs:
Linear alkylbenzenes, wt.% - 97.6
Bromine number, gVr ^2/100 g - 0.004
The average molecular weight is 239
Characteristic of the obtained oil base:
Kinematic viscosity at 100 ^o С, mm ² / s - 6.5
Viscosity Index - 126
Pour point, ^o C - minus 56
Flash point, ^o С - 238
Examples 2-12
Carried out analogously to example 1. The conditions of the experiments and the characteristics of the obtained products are shown in the table. However, in example 2 using a mixture of fresh and return benzene in the ratio,% wt. 54.7: 45.3, in example 3 this ratio is 60.8: 39.2, and in example 11 11.7: 88.3. In Example 12, 100% return benzene was taken.

The expansion of the claimed limits of the molar ratios of benzene: olefins and AlCl ₃ : olefins does not allow to obtain the target products of the required quality.

As can be seen from the above examples, in the claimed conditions for the alkylation of benzene with alpha-olefins, two target products are obtained: linear alkylbenzenes with 10-12 carbon atoms in the alkyl chain and m. 234-242 and synthetic oil with a pour point of not higher than minus 55 ^o C , a flash point of at least 190 ^o C and a kinematic viscosity of 3.8-9.5 mm ² / s at 100 ^o C.

Claims (3)

1. A method for the joint production of linear alkylbenzenes and synthetic oils, including the alkylation of benzene with alpha olefins in the presence of an aluminum chloride-based catalyst complex and the separation of benzene alkylation products to produce linear alkylbenzenes and a synthetic oil, characterized in that a mixture of individual olefins C is used as olefins ₁₀ and C ₁₂ taken in a mass ratio of 1: 3-3.67, and the process is carried out at a molar ratio of benzene: alpha-olefins = 1-8.2: 1 to achieve a mass ratio of l frosted alkylbenzenes with m.m. 234-242: oil = 1: 0.29-3.9.  2. The method according to claim 1, characterized in that the process is carried out at a molar ratio of aluminum chloride: alpha-olefins = 0.0044-0.037: 1.  3. The method according to claim 1, characterized in that as benzene use fresh benzene, or return benzene, or a mixture of fresh and return benzene from the stage of separation of benzene alkylation products with alpha-olefins in any ratio.

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