CN108525703A - A kind of ionic-liquid catalyst and preparation method thereof preparing high carbon chain alkylbenzene - Google Patents

Abstract

The present invention relates to a kind of ionic-liquid catalysts and preparation method thereof preparing high carbon chain alkylbenzene for long chain olefin alkylation, the catalyst is obtained with bisgallic acid type ionic liquid and metal chloride, bisgallic acid type ionic liquid is to carry out anion exchange with lewis acid by sulfonic acid type ion liquid to be prepared, sulfonic acid type ion liquid is to be reacted with hydrochloric acid by ionic liquid presoma and obtained, ionic liquid presoma is to be reacted to be made with alkane sultone by alkyl imidazole, and the general structure of the catalyst is：Wherein, R₁ForIn one kind；R₂For M₁For metal Al or Fe；M₂M₃For the combination of any two metal in W metal, Cu, Zn, Sn；N is 7~10.

Description

A kind of ionic liquid catalyst for preparing high carbon chain alkylbenzene and preparation method thereof

technical field

The invention relates to an ionic liquid catalyst used for the alkylation of long-chain olefins to prepare high-carbon chain alkylbenzenes and a preparation method thereof, belonging to the catalyst preparation technology in the field of organic synthesis.

Background technique

High-carbon chain alkylbenzene is the main raw material of synthetic detergent sodium alkylbenzene sulfonate, which is composed of toluene (xylene, ethylbenzene, benzene, etc.) It is produced by alkylation reaction under the influence of AlCl ₃ , HF, BF ₃ , concentrated sulfuric acid, etc., but most of these catalysts are highly corrosive and toxic, especially for equipment, and the investment is relatively high. Large, high equipment requirements, and there are problems such as difficult product post-processing and many "three wastes". Therefore, the development of environmentally friendly, low-corrosion, and recyclable acidic catalysts is the general trend.

As a special form of ionic compound, ionic liquid is widely used in organic synthesis reactions. It plays a very important role as solvent, catalyst and template agent, and has great significance in chemical synthesis and chemical industry application. Acidic ionic liquid has many advantages of both solid acid and liquid acid. In the application of many organic reactions such as esterification reaction and alkylation reaction, it provides and improves the suitable reaction conditions, improves the reaction conversion rate and reduces the cost. And the environment is friendly. Therefore, the application of ionic liquids in catalysts has received great attention, and acidic ionic liquids can effectively replace inorganic acids for corresponding catalytic reactions.

In recent years, there have been more and more reports on the preparation of chloroaluminate-type ionic liquids by combining aluminum trichloride with imidazolium salts or alkylammonium salts. Chinese patent CN1225617A reports the use of aluminum trichloride and alkyl-containing Chloroaluminate-type ionic liquid catalysts were prepared in combination with amine organic salts, which are used to catalyze the alkylation reaction of olefins with an average carbon number of C10 or more and chlorinated alkanes with an average carbon number of C6 or more; Chinese patent CN102703112A introduces a Preparation method of chlorogallate ionic liquid catalyst modified with additives, the catalyst is used to catalyze the alkylation reaction of butene and isobutane; Chinese patent CN106939173A introduces a sulfuric acid and ionic liquid [BMIM][PF ₆ ] A method for preparing a composite catalyst, which is used to catalyze the alkylation of isobutane and C4 olefins; Chinese patent CN102516128A discloses a process for synthesizing methyl diphenylmethane dicarbamate catalyzed by Bronsted-Lewis acidic ionic liquid, the ionic liquid catalyst It has good catalytic performance, but the catalyst has problems such as unstable structure and poor recycling performance during use. Most of the catalysts reported in the above studies are applied to the alkylation reaction of light olefins, and there are few research reports on the alkylation reaction of long-chain olefins. Therefore, the development of an ionic liquid catalyst for the alkylation of long-chain olefins to prepare high-carbon-chain alkylbenzenes has good theoretical significance and application prospects.

Contents of the invention

Technical problem: The purpose of this invention is to provide a kind of ionic liquid catalyst and preparation method thereof for the alkylation of long-chain olefins to prepare high-carbon chain alkylbenzene. Obtained, bis-acid ionic liquid is prepared by anion exchange between sulfonic acid ionic liquid and Lewis acid, sulfonic acid ionic liquid is obtained by reacting ionic liquid precursor with hydrochloric acid, and ionic liquid precursor is made of alkylimidazole It can be obtained by reacting with alkanes sultones.

Technical solution: An ionic liquid catalyst for the preparation of high-carbon chain alkylbenzene of the present invention is obtained by combining a bis-acid ionic liquid with a metal chloride, and the bis-acid ionic liquid is prepared by a sulfonic acid ionic liquid and a Lewis acid. It is prepared by anion exchange. The sulfonic acid type ionic liquid is obtained by the reaction of the ionic liquid precursor and hydrochloric acid. The ionic liquid precursor is prepared by the reaction of alkylimidazole and alkane sultone. The general structural formula of the catalyst is:

where _R1 is one of

_R2 is

M ₁ is metal Al or Fe; M ₂ M ₃ is a combination of any two metals in Ni, Cu, Zn and Sn; n is 7-10.

Ionic Liquid Catalysts for Alkylation of Long-Chain Olefins to High-carbon Alkanes

The preparation method of the ionic liquid catalyst preparing high carbon chain alkylbenzene of the present invention is:

Step a) At room temperature, add alkane sultone and alkylimidazole to the reaction kettle, react at 50°C-80°C for 6-12 hours, after cooling down to room temperature, stand and separate layers, remove the upper layer of organic matter to obtain the lower layer product, press each time Organic solvent: the mass ratio of the lower layer product is 0.5:1~3:1, wash the lower layer product with organic solvent for 1~3 times, let it stand for stratification, remove the organic solvent washing layer, and wash the lower layer product at 60℃~70℃ Dry under vacuum for 2-6 hours to obtain the ionic liquid precursor;

Step b) At room temperature, dissolve the ionic liquid precursor prepared in step a) in water, add hydrochloric acid dropwise, react for 0.1~1h after dripping for 0.1~0.5h, raise the temperature to 80°C~90°C and continue the reaction for 2~6h , 70 ℃ ~ 80 ℃ vacuum dewatering 2 ~ 3h, cooled to room temperature, to obtain sulfonic acid type ionic liquid;

Step c) At room temperature, add toluene and the sulfonic acid-type ionic liquid prepared in step b) into the reactor, add the Lewis acid in batches to the reactor, complete the addition within 1 to 3 hours, react for 0.5 to 1.5 hours, and heat up to Continue to react at 80°C to 100°C for 2 to 6 hours, and cool to room temperature to obtain a bis-acid ionic liquid;

Step d) Add the metal chloride and the bis-acid ionic liquid prepared in step c) into the reaction kettle and mix them evenly at room temperature under the protection of _N2 , react at 80°C-100°C for 1-3h, and cool to room temperature to obtain An ionic liquid catalyst for the alkylation of long-chain olefins to produce high-chain alkylbenzenes.

in,

The alkane sultone described in step a) of the preparation method is 1,3-propane sultone or 1,4-butane sultone, and the described alkyl imidazole is 1-butylimidazole, 1-pentane sultone One of imidazole or 1-hexylimidazole, and the organic solvent is one of ethyl acetate, ether or toluene or a combination of both.

The hydrochloric acid described in step b) of the preparation method is a 20wt.%-30wt.% hydrochloric acid aqueous solution.

The Lewis acid in step c) of the preparation method is AlCl ₃ or FeCl ₃ , and the metal chloride is a combination of any two of NiCl ₂ , ZnCl ₂ , CuCl ₂ , CuCl, SnCl ₂ , and SnCl ₄ .

In step a) of the preparation method, the molar ratio of the alkane sultone:alkylimidazole is 1:1˜2:1.

In step b) of the preparation method, the mass ratio of water:ionic liquid precursor is 2:1-5:1; the mass ratio of hydrochloric acid:ionic liquid precursor is 0.1:1-0.4:1.

In the step c) of the preparation method, the volume ratio of toluene:sulfonic acid type ionic liquid is 1:1-3:1, and the molar ratio of Lewis acid:sulfonic acid type ionic liquid is 1:1-4:1.

In step d) of the preparation method, the mass ratio of metal chloride:bisacid-type ionic liquid is 0.001:1˜0.01:1.

Beneficial effect: the object of the present invention is to provide a kind of ionic liquid catalyst and preparation method thereof for the alkylation of long-chain olefins to prepare high-carbon chain alkylbenzene, the catalyst is formed by the coordination of bis-acid ionic liquid and metal chloride Obtained, bis-acid ionic liquid is prepared by anion exchange between sulfonic acid ionic liquid and Lewis acid, sulfonic acid ionic liquid is obtained by reacting ionic liquid precursor with hydrochloric acid, and ionic liquid precursor is made of alkylimidazole It can be obtained by reacting with alkanes sultones. The features of the present invention are:

(1) The ionic liquid catalyst is synthesized from alkylimidazole, alkane sultone, Lewis acid and metal chloride, and has the double-acid characteristics of Bronsted acidity and Lewis acidity. The synergistic effect can better improve the reaction activity, and the reaction conversion rate is also greatly improved.

(2) The anion part of the ionic catalyst contains three kinds of metals, and the catalytic performance of the ionic catalyst can be adjusted by adjusting the metal type, metal valence state and metal combination, such as: Al ³⁺ , Zn ²⁺ , Cu ⁺ The combination of three valence metals can form an "inverted cone" structure with empty coordination sites. This structure has high structural stability, so the structural stability of the ion catalyst is significantly improved, so the use of the catalyst is greatly improved. In addition, the vacant coordination sites in the structure will preferentially coordinate with olefins, which plays a role in stabilizing olefins, reducing the occurrence of side reactions, and improving catalytic selectivity and product yield.

Detailed ways

The present invention provides an ionic liquid catalyst for the alkylation of long-chain olefins to prepare high-carbon-chain alkylbenzenes and a preparation method thereof. Ionic liquids are prepared by anion exchange between sulfonic acid-type ionic liquids and Lewis acids. Sulfonic acid-type ionic liquids are obtained by reacting ionic liquid precursors with hydrochloric acid. The reaction is made.

The preparation method of the ionic liquid catalyst used for the alkylation of long-chain olefins to prepare high-carbon chain alkylbenzenes is as follows:

Step a) At room temperature, according to the molar ratio of alkane sultone: alkylimidazole is 1:1~2:1, add alkylimidazole and alkane sultone into the reaction kettle, and react at 50°C~80°C for 6~12h , after cooling down to room temperature, let stand for stratification, remove the organic matter in the upper layer to obtain the lower layer product, each time according to the mass ratio of organic solvent: lower layer product is 0.5:1 to 3:1, wash the lower layer product with organic solvent 1 to 3 times, statically Put layers into layers, remove the organic solvent washing layer, and vacuum dry the washed lower layer product at 60°C-70°C for 2-6 hours to obtain the ionic liquid precursor;

step b) at room temperature, according to the mass ratio of water: ionic liquid precursor is 2:1 ~ 5:1, the ionic liquid precursor prepared in step a) is dissolved in water, according to the mass ratio of hydrochloric acid: ionic liquid precursor 0.1:1～0.4:1, add hydrochloric acid dropwise, react for 0.1～1h after dripping for 0.1～0.5h, raise the temperature to 80℃～90℃ and continue the reaction for 2～6h, remove water under vacuum at 70℃～80℃ for 2～ 3h, get sulfonic acid type ionic liquid;

Step c) At room temperature, according to the volume ratio of toluene: sulfonic acid type ionic liquid is 1:1 ~ 3:1, add toluene and the sulfonic acid type ionic liquid prepared in step b) into the reaction kettle, according to Lewis acid: sulfonic acid type ionic liquid The molar ratio of the acid-type ionic liquid is 1:1-4:1. Add the Lewis acid to the reactor in batches, and finish adding within 1-3 hours. React for 0.5-1.5 hours, then raise the temperature to 80°C-100°C and continue the reaction for 2-6 hours. , cooled to room temperature to obtain a bis-acid ionic liquid;

Step d) At room temperature and under the protection of _N2 , according to the mass ratio of metal chloride: bis-acid type ionic liquid of 0.001:1 to 0.01:1, adding the metal chloride and the bis-acid type ionic liquid prepared in step c) to react Mix in the still, react at 80°C-100°C for 1-3h, and cool to room temperature to obtain an ionic liquid catalyst for the alkylation of long-chain olefins to prepare high-chain alkylbenzenes.

The alkane sultone described in step a) of the above-mentioned preparation method of an ionic liquid catalyst for the alkylation of long-chain olefins to prepare high-carbon chain alkylbenzenes is 1,3-propane sultone or 1,4-butane sultone lactone, the alkyl imidazole is one of 1-butyl imidazole, 1-pentylimidazole, and 1-hexylimidazole, and the organic solvent is one or both of ethyl acetate, ether, and toluene. The combination of species; the hydrochloric acid described in the preparation method step b) is 20wt.～30wt.% hydrochloric acid aqueous solution; the Lewis acid described in the preparation method step c) is _AlCl3 or _FeCl3 , and the described metal chloride is NiCl _2. A combination of two of ZnCl ₂ , CuCl ₂ , CuCl, SnCl ₂ , and SnCl ₄ .

Catalyst Alkylation Performance Evaluation:

Press ionic liquid catalyst: the mass ratio of long-chain olefin is 0.1:1, toluene (or xylene or ethylbenzene or benzene): the molar ratio of long-chain olefin is 10:1, will toluene (or xylene or ethylbenzene or benzene ), long-chain olefins and ionic liquid catalysts were added to the reactor, reacted at 50°C for 0.5h, cooled to room temperature, and after standing for stratification, the organic matter in the upper layer was taken for distillation to remove unreacted toluene (or xylene or ethyl alcohol) in the raw material. Benzene or benzene), to obtain high-carbon chain alkylbenzene. Investigate the bromine value of high carbon chain alkylbenzene.

Determine the bromine value X of benzene products according to GB/T1815, and the calculation formula is:

X(g/100mL)＝(V ₁ -V ₂ )×0.008÷5×100

V ₁ : the amount of sodium thiosulfate standard solution consumed during the blank test, mL;

V ₂ : the amount of sodium thiosulfate standard solution consumed during the titration test, mL;

0.008: The amount of 1mL sodium thiosulfate standard solution is equivalent to the amount of bromine, g.

The ionic liquid catalyst used for the alkylation of long-chain olefins to prepare high-carbon chain alkylbenzenes of the present invention is obtained by coordinating a bis-acid type ionic liquid with a metal chloride, and the bis-acid type ionic liquid is obtained by combining a sulfonic acid type ionic liquid with a metal chloride The Lewis acid is prepared by anion exchange, and the sulfonic acid-type ionic liquid is prepared by reacting an ionic liquid precursor with hydrochloric acid, and the ionic liquid precursor is prepared by reacting an alkylimidazole with an alkane sultone.

Example 1:

At 25°C, add 12.214g of 1,3-propane sultone and 12.418g of 1-butylimidazole into the reaction kettle, react at 50°C for 6h, after cooling down to room temperature, let stand to separate layers, and the lower layer product is mixed with 12.316 g of ethyl acetate was washed, and the washed lower layer product was vacuum-dried at 60°C for 2h to obtain an ionic liquid precursor; at 25°C, all the above-mentioned ionic liquid precursors were dissolved in 49.265g of water, and 2.463g of 20wt. % hydrochloric acid aqueous solution, after dripping within 6 minutes, react for 6 minutes, raise the temperature to 80°C and continue the reaction for 2h, remove water under vacuum for 2h at 70°C, and obtain a sulfonic acid ionic liquid; at 25°C, the above sulfonic acid ionic liquid Put everything into the reaction kettle, add 30mL of toluene, then add 13.333g of AlCl ₃ into the reaction kettle in batches, after adding within 1h, react for 0.5h, raise the temperature to 80°C and continue the reaction for 2h, cool to room temperature, and obtain the bis-acid type Ionic liquid; under the protection of _N2 at 25°C, add 0.0380g of _NiCl2 and 0.0380g of _ZnCl2 into the above-mentioned bis-acid type ionic liquid, mix well, react at 80°C for 1h, cool to room temperature, and obtain Ionic liquid catalysts for the alkylation of long-chain olefins to high-chain alkylbenzenes.

Add 92.138g of toluene, 25.200g of octadecene and 2.520g of ionic liquid catalyst into the reaction kettle, react at 50°C for 0.5h, cool to room temperature, and after standing to separate layers, take the upper organic matter and carry out distillation to remove unreacted raw materials. of toluene to obtain long-chain alkylbenzenes. The bromine value of this long-chain alkylbenzene was 0.071 g/100 mL.

Example 2:

At 25°C, add 27.234g of 1,4-butane sultone and 13.821g of 1-pentylimidazole into the reaction kettle, and react at 80°C for 12h. 82.314g of diethyl ether was washed three times, and the washed lower layer product was vacuum-dried at 70°C for 6h to obtain an ionic liquid precursor; at 25°C, all the above-mentioned ionic liquid precursors were dissolved in 137.190g of water, and 10.976g of 30wt. % hydrochloric acid aqueous solution, after 0.5h of dripping, react for 1h, heat up to 90°C and continue to react for 6h, and vacuum remove water for 3h at 80°C to obtain sulfonic acid ionic liquid; at 25°C, all the above sulfonic acid ionic liquid Put it into the reaction kettle, add 90mL of toluene, add _48.661g of FeCl3 into the reaction kettle in batches, after 3h of addition, react for 1.5h, raise the temperature to 100°C and continue the reaction for 6h, cool to room temperature, and obtain the bis-acid ionic liquid; Add 0.924g of CuCl ₂ and 0.924g of CuCl to the above-mentioned bis-acid ionic liquid at 25°C under the protection of _N2 , mix well, react at 100°C for 3 hours, and cool to room temperature to obtain long-chain alkenes Ionic liquid catalysts for the preparation of high-carbon chain alkylbenzenes.

Add 106.2g of xylene, 22.400g of hexadecene and 2.240g of ionic liquid catalyst into the reaction kettle, react at 50°C for 0.5h, cool to room temperature, and after standing for stratification, take the upper organic matter and carry out distillation to remove untreated Reaction of xylene, high carbon chain alkyl benzene. The bromine value of this higher carbon chain alkylbenzene is 0.016g/100mL.

Example 3:

At 25°C, add 20.426g of 1,4-butane sultone and 15.224g of 1-hexylimidazole into the reaction kettle, react at 70°C for 8h, after cooling down to room temperature, let stand and separate the layers, and the lower layer product is mixed with 43.261 g of toluene was washed twice, and the washed lower layer product was vacuum-dried at 65°C for 4 hours to obtain an ionic liquid precursor; at 25°C, all the above-mentioned ionic liquid precursors were dissolved in 86.520g of water, and 5.768g of 25wt.% Hydrochloric acid aqueous solution, after 18 minutes of dripping, react for 0.5h, heat up to 85°C and continue to react for 3h, remove water in vacuum at 75°C for 2.5h, and obtain sulfonic acid ionic liquid; Put everything into the reaction kettle, add 60mL of toluene, add _26.667g of AlCl3 into the reaction kettle in batches, after 2h of addition, react for 1h, raise the temperature to 90°C and continue the reaction for 4h, cool to room temperature, and obtain the bis-acid ionic liquid; Add 0.278g of SnCl ₂ and 0.278g of SnCl ₄ into the above-mentioned bis-acid ionic liquid at 25°C under the protection of _N2 , mix well, react at 90°C for 2 hours, and cool to room temperature to obtain long-chain olefins An ionic liquid catalyst for the preparation of high-carbon chain alkylbenzenes by alkylation.

Add 106.2g of ethylbenzene, 25.200g of octadecene and 2.520g of ionic liquid catalyst into the reaction kettle, react at 50°C for 0.5h, cool to room temperature, and after standing to separate layers, take the upper layer of organic matter and carry out distillation to remove unsaturated ions in the raw materials. Reaction of ethylbenzene, high carbon chain alkylbenzene. The bromine value of this higher carbon chain alkylbenzene is 0.002g/100mL.

Example 4:

At 25°C, add 20.426g of 1,4-butane sultone and 15.224g of 1-hexylimidazole into the reaction kettle, react at 80°C for 10h, after cooling down to room temperature, let stand to separate layers, and the lower layer product is mixed with 43.261 g of toluene was washed 3 times, and the washed lower layer product was vacuum-dried at 65°C for 3 hours to obtain an ionic liquid precursor; at 25°C, all the above-mentioned ionic liquid precursors were dissolved in 57.680g of water, and 5.768g of 20wt.% Hydrochloric acid aqueous solution, after 12 minutes of dripping, react for 48 minutes, heat up to 85°C and continue to react for 4h, and vacuum remove water for 2h at 75°C to obtain sulfonic acid ionic liquid; at 25°C, all the above sulfonic acid ionic liquid Put it into the reaction kettle, add 45mL of toluene, add _26.667g of AlCl3 into the reaction kettle in batches, after 2h of addition, react for 1h, raise the temperature to 80°C and continue the reaction for 5h, cool to room temperature, and obtain the bis-acid ionic liquid; Add 0.167g of SnCl ₂ and 0.111g of SnCl ₄ into the above-mentioned bis-acid ionic liquid at 25°C under the protection of N ₂ , mix well, react at 90°C for 2 hours, and cool to room temperature to obtain long-chain alkenes Ionic liquid catalysts for the preparation of high-carbon chain alkylbenzenes.

Add 78.114g of benzene, 22.400g of hexadecene and 2.240g of ionic liquid catalyst into the reaction kettle, react at 50°C for 0.5h, cool to room temperature, and after standing to separate layers, take the upper organic matter and carry out distillation to remove unreacted raw materials. Benzene to obtain high-carbon chain alkylbenzene. The bromine value of this higher carbon alkylbenzene was 0.014g/100mL.

Example 5:

At 25°C, add 20.426g of 1,4-butane sultone and 12.418g of 1-butylimidazole into the reaction kettle, react at 80°C for 7h, after cooling down to room temperature, let stand and separate, and use the lower layer product 26.035g of toluene was washed three times, and the washed lower layer product was vacuum-dried at 70°C for 2 hours to obtain an ionic liquid precursor; at 25°C, all the above-mentioned ionic liquid precursors were dissolved in 52.071g of water, and 4.927g of 30wt. % hydrochloric acid aqueous solution, after 18 minutes of dripping, react for 1 hour, heat up to 85°C and continue to react for 6h, remove water under vacuum for 2.5h at 75°C, and obtain sulfonic acid ionic liquid; Put everything into the reaction kettle, add 60mL of toluene, add _26.667g of AlCl3 into the reaction kettle in batches, after 2h of addition, react for 1h, raise the temperature to 80°C and continue the reaction for 3h, cool to room temperature, and obtain the bis-acid ionic liquid; Add 0.103g of SnCl ₂ and 0.103g of CuCl to the above-mentioned bis-acid ionic liquid at 25°C under the protection of N ₂ , mix well, react at 90°C for 3 hours, and cool to room temperature to obtain long-chain alkenes Ionic liquid catalysts for the preparation of high-carbon chain alkylbenzenes.

Add 92.138g of toluene, 25.200g of octadecene and 2.520g of ionic liquid catalyst into the reaction kettle, react at 50°C for 0.5h, cool to room temperature, and after standing to separate layers, take the upper organic matter and carry out distillation to remove unreacted raw materials. of toluene to obtain high-carbon chain alkylbenzene. The bromine value of the higher chain alkylbenzene was 0.004g/100mL.

Claims (9)

1. An ionic liquid catalyst for preparing high-carbon-chain alkylbenzene is characterized in that the catalyst is prepared by matching a double-acid type ionic liquid with a metal chloride, the double-acid type ionic liquid is prepared by carrying out anion exchange on a sulfonic acid type ionic liquid and Lewis acid, the sulfonic acid type ionic liquid is prepared by reacting an ionic liquid precursor with hydrochloric acid, the ionic liquid precursor is prepared by reacting alkyl imidazole and alkane sultone, and the structural general formula of the catalyst is as follows:

wherein R is₁Is composed ofOne of (1);

R₂is composed of

M₁Is metal Al or Fe; m₂M₃Is the combination of any two metals of Ni, Cu, Zn and Sn; n is 7 to 10.

Ionic liquid catalyst for preparing high-carbon-chain alkylbenzene by alkylation of long-chain olefin

2. The preparation method of the ionic liquid catalyst for preparing high carbon chain alkylbenzene according to claim 1, which is characterized by comprising the following steps:

step a), adding alkane sultone and alkyl imidazole into a reaction kettle at room temperature, reacting for 6-12 h at 50-80 ℃, cooling to room temperature, standing for layering, and removing upper organic matters to obtain a lower product, wherein the organic solvent is used for: washing the lower-layer product for 1-3 times by using an organic solvent according to the mass ratio of the lower-layer product to the lower-layer product of 0.5: 1-3: 1, standing for layering, removing an organic solvent washing layer, and drying the washed lower-layer product at 60-70 ℃ for 2-6 hours in vacuum to obtain an ionic liquid precursor;

step b) at room temperature, dissolving the ionic liquid precursor prepared in the step a) in water, dropwise adding hydrochloric acid, reacting for 0.1-1 h after 0.1-0.5 h of dropwise adding, heating to 80-90 ℃, continuing to react for 2-6 h, removing water in vacuum at 70-80 ℃ for 2-3 h, and cooling to room temperature to obtain sulfonic acid type ionic liquid;

step c), at room temperature, adding toluene and the sulfonic acid type ionic liquid prepared in the step b) into a reaction kettle, adding Lewis acid into the reaction kettle in batches, completing the addition within 1-3 h, reacting for 0.5-1.5 h, heating to 80-100 ℃, continuing to react for 2-6 h, and cooling to room temperature to obtain the double-acid type ionic liquid;

step d) at room temperature, N₂Under protection, adding the metal chloride and the diacid ionic liquid prepared in the step c) into a reaction kettle, uniformly mixing, reacting for 1-3 h at the temperature of 80-100 ℃, and cooling to room temperature to obtain the ionic liquid catalyst for preparing high-carbon-chain alkylbenzene by alkylation of long-chain olefin.

3. The method of claim 2, wherein the alkane sultone in step a) is 1, 3-propane sultone or 1, 4-butane sultone, the alkyl imidazole is one of 1-butyl imidazole, 1-pentyl imidazole or 1-hexyl imidazole, and the organic solvent is one or a combination of ethyl acetate, diethyl ether or toluene.

4. The method for preparing ionic liquid catalyst for preparing high carbon chain alkylbenzene according to claim 2, wherein the hydrochloric acid in step b) is 20-30 wt.% aqueous hydrochloric acid solution.

5. The method for preparing ionic liquid catalyst for preparing high carbon chain alkyl benzene as claimed in claim 2, wherein the Lewis acid is AlCl in step c) of the preparation method₃Or FeCl₃The metal chloride is NiCl₂、ZnCl₂、CuCl₂、CuCl、SnCl₂、SnCl₄A combination of any two of the above.

6. The method for preparing an ionic liquid catalyst for preparing high carbon chain alkylbenzene as claimed in claim 2, wherein in step a) of the preparation method, the ratio of alkane sultone: the molar ratio of the alkyl imidazole is 1:1 to 2: 1.

7. The method for preparing ionic liquid catalyst for preparing high carbon chain alkyl benzene as claimed in claim 2, wherein in the step b) of the preparation method, the water: the mass ratio of the ionic liquid precursor is 2: 1-5: 1; the hydrochloric acid: the mass ratio of the ionic liquid precursor is 0.1: 1-0.4: 1.

8. The method for preparing ionic liquid catalyst for preparing high carbon chain alkyl benzene as claimed in claim 2, wherein the ratio of toluene: the volume ratio of the sulfonic acid type ionic liquid is 1: 1-3: 1, and the Lewis acid: the molar ratio of the sulfonic acid type ionic liquid is 1: 1-4: 1.

9. The method for preparing ionic liquid catalyst for preparing high carbon chain alkyl benzene as claimed in claim 2, wherein in step d) of the preparation method, the ratio of metal chloride: the mass ratio of the double-acid ionic liquid is 0.001: 1-0.01: 1.