Ionic liquid catalyst for synthesizing long-chain alkylbenzene as well as preparation method and application of ionic liquid catalyst

Abstract

The invention belongs to the technical field of chemical production, and particularly relates to an ionic liquid catalyst for synthesizing long-chain alkylbenzene as well as a preparation method and application of the ionic liquid catalyst. The ionic liquid catalyst is a mixed multi-acidic ionic liquid catalyst and mainly comprises two ionic liquids with different properties. Wherein the cation of at least one ionic liquid is derived from a hydrohalide or quaternary ammonium salt of an amine substituted by an alkyl group, and the other ionic liquid is an acidic ionic liquid. The ionic liquid catalyst can be applied to the reaction of long straight-chain olefin or mixed olefin raw materials and benzene to synthesize long-chain alkylbenzene, the reaction condition is mild, the product conversion rate is high, and the monoalkylbenzene selectivity is good. The catalyst has excellent raw material compatibility and recycling performance.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical production, and particularly relates to an ionic liquid catalyst for synthesizing long-chain alkylbenzene and a preparation method and application thereof. Background Art

[0002] The Fischer-Tropsch synthesis product contains a large amount of olefins, especially linear α-olefins, which are valuable raw materials for processing and producing high-end chemicals. In particular, long straight-chain olefins with different carbon numbers are suitable for processing into different products. 11 -C 13 It can be used to produce alkylbenzene products for detergents, and C 14 -C 20 It can be used to produce heavy alkylbenzene products. Heavy alkylbenzene can also be widely used as lubricants, lubricant additives, oilfield tertiary oil recovery agents, hydraulic oils, heat transfer oils, electrical oils, corrosion inhibitors, etc., and has high economic value. The development of long-chain alkylbenzene synthesis technology can achieve high-value and diversified utilization of high-carbon number fractions in Fischer-Tropsch synthesis products, enrich the product structure of coal indirect liquefaction, and improve the economic benefits of the Fischer-Tropsch synthesis industry. Compared with the traditional petroleum-based alkylbenzene synthesis process, the process route for preparing alkylbenzene from Fischer-Tropsch products is simpler and has more cost advantages.

[0003] Alkylbenzene synthesis is a Friedel-Crafts reaction catalyzed by protonic acid or Lewis acid. The mechanism can be explained by carbon cations or complexes, and the reaction type is an electrophilic substitution reaction of the benzene ring. In the early traditional process, production mainly used traditional acids (such as hydrofluoric acid, aluminum chloride, etc.) as catalysts. However, traditional acid catalysts are highly corrosive and have serious impacts on the environment. Therefore, many relatively environmentally friendly and safe new catalytic processes have been developed one after another. Ionic liquid catalytic systems are one of the research and development directions with industrial prospects.

[0004] Ionic liquid is a substance that is completely composed of anions and cations and is liquid at room temperature or near room temperature. As a new type of catalyst, it has the characteristics of good fluidity, high density of active sites and low volatility, and has high low-temperature activity to achieve high conversion rate. In recent years, ionic liquid catalysts have been widely used in the research and development of alkylation reactions and alkylbenzene product preparation due to their unique properties, including high thermal stability, adjustable acidity / basicity and the ability to promote heterogeneous catalysis.

[0005] Ionic liquid catalysts, especially chloroaluminate-type ionic liquids, are mostly used for long-chain alkylation reactions of aromatic hydrocarbons. The catalytic activity depends on the composition and structure of the anion, i.e., various forms of chloroaluminate ions. The ionic liquid catalytic system also has the advantage of easy acidity adjustment. In addition, the amount of ionic liquid used as a catalyst (as a percentage of the alkylation raw material) is significantly lower than that of traditional catalysts, which also provides convenience for industrial storage and transportation, as well as higher safety.

[0006] Patent CN101365664A discloses a method for preparing alkylated aromatic compounds using an acidic ionic liquid catalyst, wherein the first component of the ionic liquid in the method comprises an aluminum / gallium halide or an alkyl aluminum / gallium halide, and the second component comprises a salt selected from an ammonium salt, a phosphonium salt or a sulfonium salt.

[0007] Patent CN102660322B discloses laboratory and thousand-ton scale heavy alkylbenzene synthesis processes, and methods for preparing two catalysts: aluminum chloride and aromatic hydrocarbons are complexed in proportion; aluminum chloride is mixed with organic amine hydrochloride in hydrogenated gasoline in a proportion to form an ionic liquid.

[0008] Patent US9328037B2 discloses halogen metal salt ionic liquids for producing alkylbenzenes, and separation methods thereof by gravity stratification, adsorption or extraction. The method uses chloro-1-butyl-3-methylimidazolium chloroaluminate ionic liquid to catalyze the alkylation reaction of benzene with 1-dodecene. After the ionic liquid is circulated 5 times, the conversion rate of 1-dodecene can still reach 100%, and the selectivity of monoalkylbenzene is greater than 90%.

[0009] Patents CN104549506B and CN104549507B respectively disclose a preparation method using an aluminum- and iron-based ionic liquid having a perfluoroalkylsulfonyl imide structure as a catalyst for synthesizing alkylbenzene.

[0010] Patent CN109721462B discloses a method for preparing long-chain alkylbenzenes, wherein metal compound additives and quinoline and benzimidazole ionic liquids are used as catalysts. 10 -C 18 Long-chain alkylbenzenes are prepared from linear olefins.

[0011] Patent CN108525703B discloses an ionic liquid catalyst for preparing high-carbon chain alkylbenzene and a preparation method thereof. In the method, a double acid type ionic liquid is combined with an ionic liquid catalyst of a metal chloride to synthesize a long-chain alkylbenzene.

[0012] Patent CN112403515A discloses a method for preparing an asymmetric bimetallic dicationic liquid catalyst and its application. The ionic liquid prepared by the method catalyzes the reaction of toluene and octadecene, and the conversion rate obtained is 99.92% and the selectivity is 32.99%.

[0013] Traditional acid catalytic systems have problems with corrosion and subsequent process treatment that is not environmentally friendly. The existing ionic liquid catalytic system still has room for improvement in some aspects, such as the limited mass of olefins that can be converted per unit mass of catalytically active components; it cannot effectively adapt to diverse raw material sources or raw materials with complex component composition, such as high-temperature Fischer-Tropsch synthesis product raw materials. In addition, the existing ionic liquid catalysts still have room for improvement in terms of reaction activity, selectivity, raw material adaptability, and recyclability. Summary of the invention

[0014] The purpose of the present invention is to provide an ionic liquid catalyst for synthesizing long-chain alkylbenzenes and its preparation method and application, so as to solve the problems existing in the prior art. The present invention proposes a mixed polyacidic ionic liquid catalyst, which comprises two ionic liquids of different properties, wherein the cation of at least one ionic liquid is derived from a hydrogen halide or quaternary ammonium salt of an amine substituted by an alkyl group, and the other ionic liquid is an acidic ionic liquid. The method of the present invention also provides a corresponding preparation method. The present invention further provides a method for synthesizing long-chain alkylbenzenes under ionic liquid catalysis, which can be carried out under mild reaction conditions to obtain a higher conversion rate and monoalkylbenzene selectivity. Other features include: it can be applied to long straight-chain olefins (C 10 -C 22 ) can be used as the alkylating agent raw material, and a mixed olefin raw material containing a certain amount of other types of components or impurities can be used as the alkylating agent raw material, such as the Fischer-Tropsch synthesis product.

[0015] According to a first aspect of the present invention, an ionic liquid catalyst is provided, specifically a mixed polyacidic ionic liquid catalyst, which comprises two ionic liquids of different properties, wherein the cation of at least one ionic liquid is derived from a hydrohalide or quaternary ammonium salt of an amine substituted by an alkyl group, and the other ionic liquid is an acidic ionic liquid.

[0016] As a preferred embodiment, the cation is derived from at least one of trimethylamine hydrochloride, triethylamine hydrochloride, dodecyldimethylbenzylammonium chloride, hexadecyltrimethylammonium chloride, benzyltrimethylammonium chloride, tetramethylammonium chloride, tetraethylammonium bromide, tetrabutylammonium bromide, benzyltributylammonium chloride, allyltrimethylammonium chloride, dimethyldioctadecylammonium chloride and methyltrioctylammonium chloride.

[0017] As a preferred embodiment, the anion in the ionic liquid corresponding to the cation is selected from one or a combination of halide ion, hexafluorophosphate, trifluoromethanesulfonate, bis(trifluoromethylsulfonyl)imide ion, methanesulfonate, benzenesulfonate, hydrogen sulfate, dihydrogen phosphate, chloroaluminate, ferric chloride and toluenesulfonate.

[0018] As a preferred embodiment, the acidic ionic liquid is selected from at least one of quaternary ammonium salt type diacidic ionic liquids, ionic liquids of ammonium salt cations added with auxiliary strong acidic substances, and ionic liquids of imidazole cations added with auxiliary strong acidic substances.

[0019] As a preferred embodiment, the ionic liquid catalyst further comprises an auxiliary agent, which is a metal compound and / or a strong acidic substance, wherein the metal compound is selected from one or a combination of aluminum chloride, ferric chloride, cupric chloride, cuprous chloride, zinc chloride, aluminum trifluoromethanesulfonate and copper trifluoromethanesulfonate; and the strong acidic substance is selected from at least one of trifluoromethanesulfonic acid, 1,1,2,2-tetrafluoroethylsulfonic acid, toluenesulfonic acid and trifluoroacetic acid.

[0020] According to the second aspect of the present invention, a method for preparing an ionic liquid catalyst is further provided, wherein the preparation method comprises mixing an ammonium salt cationic ionic liquid and an acidic ionic liquid in proportion, and combining them uniformly by sufficient stirring to form a mixed polyacidic ionic liquid catalyst as described above having a synergistic catalytic effect.

[0021] As a preferred embodiment, the preparation steps of the ammonium salt cationic ionic liquid are:

[0022] First, add the ammonium salt precursor salt into a dry reactor and operate in an anhydrous and oxygen-free environment; then add a co-solvent to fully dissolve the precursor salt, and heat the reactor to a constant temperature of 10-100°C for reaction; at an appropriate stirring speed, slowly add anhydrous metal salts in batches to ensure uniform mixing; as needed, continue to add other metal compounds or strong acidic substances; finally, after stirring to a homogeneous phase, stand and separate, collect the lower layer of viscous liquid, and complete the preparation of ammonium salt cationic ionic liquid.

[0023] The anhydrous and oxygen-free environment is an anhydrous and oxygen-free glove box or a Schlenk-type nitrogen protection system; constant temperature heating causes the mixture to react into a homogeneous liquid. Once the precursor salt and the metal salt begin to mix and release heat, it is necessary to properly adjust the appropriate constant temperature heating or cooling to prevent overheating in the reaction system. Therefore, the initial constant temperature setting range is preferably 10-100°C.

[0024] Specifically, the ionic liquid catalyst finally prepared by the present invention includes cations, anions, metal halide additives and strong acidic substances.

[0025] The cation is derived from a hydrohalide or quaternary ammonium salt of an amine substituted by an alkyl group, and has a general structural formula of [R n NH 4-n ] +, wherein R represents a hydrocarbon group, and n=1-4. The hydrocarbon group is preferably a short-chain (preferably 1-4 carbon atoms) alkyl group, or three short-chain alkyl groups and one medium-long chain alkyl group. It should be noted that the hydrocarbon groups in the above compounds can be of the same carbon number and structure, or different carbon numbers and structures. The structure, length and size of the hydrocarbon group will determine the melting characteristics and viscosity, which will further affect the dispersion in the reaction system and the recovery and regeneration of subsequent processes. The hydrocarbon group can be selected from alkyl, alkenyl, benzyl, and allyl. The carbon number range of the alkyl group is 1-18, preferably 1-4.

[0026] As a preferred embodiment, the co-solvent is selected from liquid paraffin or medium-long chain normal alkanes (with a carbon number ranging from 6 to 18).

[0027] As a preferred embodiment, the mixing mass ratio of the ammonium salt cationic ionic liquid to the acidic ionic liquid is 1-20.

[0028] According to the third aspect of the present invention, a method for synthesizing long-chain alkylbenzene is further provided, and the specific synthesis steps are as follows:

[0029] Add an appropriate amount of benzene into the reaction vessel and heat to the reaction temperature;

[0030] Add the mixed polyacidic ionic liquid catalyst at an appropriate stirring speed to fully mix it with benzene;

[0031] gradually adding the alkylating agent dropwise at a certain rate;

[0032] The reaction temperature is maintained to continue the reaction. After the reaction is completed, stirring is stopped and the reaction mixture is taken out;

[0033] After standing and separating, the ionic liquid catalyst in the lower layer is recovered for subsequent recycling.

[0034] In the present invention, an alkylating agent and benzene are synthesized under the action of the aforementioned ionic liquid catalyst to produce long-chain alkylbenzene. The alkylating agent raw material is selected from long straight-chain olefins (C 10 -C 22 ), or a mixed olefin feedstock containing a certain amount of other types of components or impurities (such as a mixture of alkanes and olefins, Fischer-Tropsch synthesis products, etc.). Among them, long straight-chain olefins refer to monoolefins with a certain carbon number or internal olefins containing a double bond, including but not limited to 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, preferably α-olefins. Among them, the mixed olefin feedstock mentioned can be a mixture of long straight-chain olefins within a certain carbon number range and other hydrocarbon mixtures and oxygen-containing compounds with the same carbon number range. Among them, a hydrocarbon mixture refers to a mixture of one or more selected from normal olefins, isoolefins, normal alkanes, isoalkanes and aromatics. For example, a high-temperature Fischer-Tropsch synthesis product C rich in olefins12+ Distillate oil is a mixed olefin feedstock that can be used as an alkylating agent.

[0035] Wherein, the mass ratio of the ionic liquid catalyst to the alkylating agent is 1:1000-1:10. The reaction temperature is selected from 10-80°C, so that the alkylation synthesis reaction can be promoted in the initial stage of the reaction; the reaction time is 0.1-10 hours. The benzene-olefin ratio refers to the ratio of the amount of benzene added to the flask as a raw material (number of moles) to the amount of normal olefins in the alkylating agent raw material, and the range is selected from 5-30. The amount of ionic liquid catalyst refers to the percentage of its mass to the mass of the alkylating agent, and the range is selected from 0.3%-30%. Generally, in the research in this field, the proportion of the catalyst is also controlled by controlling the "acid-hydrocarbon ratio". "Acid-hydrocarbon ratio" refers to the mass ratio or volume ratio of the acid catalyst to the reaction raw material. Or the amount of catalyst added is accurately controlled by the ratio (molar ratio) of the amount of catalyst substance to the amount of normal olefin substance, and this value in the present invention is selected from 0.5%-15%. The alkylating agent dropwise addition rate range is selected from 0.1-6 g / min, and is preferably added at a uniform rate, which can be operated by a separatory funnel or a peristaltic pump.

[0036] According to a fourth aspect of the present invention, there is further provided an application of an ionic liquid catalyst for Friedel-Crafts alkylation reaction, particularly for the synthesis of long-chain alkylbenzenes.

[0037] The present invention has excellent catalytic performance and good stability for alkylation reaction by the structural design of mixed polyacidic ionic liquid and the improvement of the functionality of the whole catalytic system. The selection and design of the hydrocarbon structure in the cationic structure can effectively regulate the steric hindrance and the physical properties (viscosity, melting point and density) of the ionic liquid itself. At the same time, the introduction of anions with different degrees of acidity can provide protection of the catalytic system by hydrophobic groups while effectively regulating the acidity and acid position (electron pair acceptance ability), thereby increasing the stability while obtaining effective catalytic performance. The combination of the appropriate length of the hydrocarbon side chain and the highly hydrophobic anion is also conducive to the increase of the interface width between the reactant and the ionic liquid, thereby facilitating the diffusion and miscibility of benzene and the alkylation raw material in the ionic liquid catalyst. The CH group in the ionic liquid of the present invention forms a hydrogen bond between the π electron system (benzene ring) as an electrophile, which is conducive to the combination of the reactant and the catalyst. After the alkylbenzene reaction occurs, the long-chain substituent on the aromatic nucleus introduces additional steric hindrance, thereby causing the decrease of miscibility with the ionic liquid, thereby automatically completing the preliminary separation of the catalyst system and the product. The use of metal compounds and strong acidic substances as additives further improves the selectivity of the target product (monoalkylbenzene) and the stability of the entire catalyst system.

[0038] The specific advantages of the present invention include: under the conditions of nearly complete conversion of normal olefins in the alkylating agent raw material (conversion rate>95%) and good selectivity (monoalkylbenzene selectivity>70%), the amount of ionic liquid catalyst used is low, or the ratio of the amount of ionic liquid catalyst to the normal olefins in the alkylating agent is low, and the olefin mass that can be converted per unit mass of catalytic active components is high. Under relatively mild reaction conditions, the ionic liquid catalyst of the present invention can be directly recycled, reflecting the excellent stability of the catalyst.

[0039] In addition, the ionic liquid catalyst and the method for synthesizing long-chain alkylbenzene in the present invention have good raw material compatibility and can be applied to olefin-rich alkylating agents with various raw material sources and complex component compositions.

[0040] Other beneficial effects include: the ionic liquid in the present invention is easy to separate and circulate due to its physical properties such as density and melting point, and has good industrial process treatment conditions. DETAILED DESCRIPTION

[0041] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be noted that after reading the content covered by the present invention, for those of ordinary skill in the art, some changes and improvements can also be made without departing from the inventive concept, and these all belong to the protection scope of the present invention. The various commonly used reagents used in the embodiments are all commercially available products.

[0042] The conversion rate and selectivity specifically refer to the conversion rate of normal olefins in the alkylbenzening agent and the selectivity of monoalkylbenzene in the product, respectively, and the calculation formulas are as follows.

[0043] Normal olefins (C ＝ ) conversion rate:

[0044]

[0045] in and It is the amount of normal olefin substance before and after the reaction.

[0046] Monoalkylbenzene (AB) selectivity:

[0047]

[0048] Where N AB is the amount of monoalkylbenzene in the product, N t.p. It is the amount of substance of all products (excluding excess unreacted benzene). represents the mass fraction of normal olefins consumed in the reaction to convert into monoalkylbenzene, and is the mass fraction of normal olefins before and after the reaction. Indicates the mass fraction of linear 2-6 and branched alkylbenzenes in the product. MW AB and denote the mass-weighted average molecular weights of monoalkylbenzenes and normal olefins, respectively.

[0049] Example 1

[0050] Take 40.6g of liquid paraffin and add it into a three-necked flask, keep it at 25℃ and keep it under N 2 Under the protection of the atmosphere, 14.4 g of trimethylamine hydrochloride was added. Under high-speed stirring, 40.6 g of aluminum chloride was added to the mixture obtained previously in batches or at a constant speed in small doses. After stirring for 2 hours, the mixture was allowed to stand for a long time, and a dark brown viscous ionic liquid A was obtained by separation at the lower layer of the product. 1 , the AlCl 3 The mole fraction is 0.62.

[0051] 14.6 g of isobutylamine and 30.0 g of 1,4-butane sultone were placed in a flask and heated, stirred and refluxed at 50 ° C for 6 hours, then cooled to room temperature and filtered out the solid, washed with toluene and ether, and vacuum dried for 24 hours to obtain a white powdery solid. The above solid was dissolved in toluene and an appropriate amount of sulfuric acid was added dropwise, and continued to be stirred at 60 ° C for 24 hours. After cooling, the lower layer product was separated, and continued to be washed with a solvent, separated by rotary evaporation and vacuum dried to obtain the final yellow viscous ionic liquid A 2 .

[0052] The ionic liquid A 1 With A 2 After fully mixing at a mass ratio of 10:1, ionic liquid catalyst A was obtained.

[0053] Comparative Example 1

[0054] Take 10.6 g of 1-butyl-3-methylimidazolium chloride and add it to a three-necked flask, keep it at 30°C and pass N 2 Under high-speed stirring, 16.5 g of aluminum chloride was added in batches or at a constant speed in small doses, and stirring was continued for 4 hours and then allowed to stand for a long time. A dark brown viscous liquid ionic liquid product was collected and recorded as ionic liquid B. The AlCl 3 The mole fraction is 0.67.

[0055] Example 2

[0056] Take 44.7g of liquid paraffin and add it into a three-necked flask, keep it at a constant temperature of 30℃ and N 2Under the protection of atmosphere, 21.2 g of triethylamine hydrochloride was added. Under high-speed stirring, 45.7 g of aluminum chloride was added to the mixture obtained previously in batches or at a constant speed in small doses. After stirring for 2 hours, the mixture was allowed to stand for a long time. A dark brown viscous ionic liquid C was obtained at the bottom of the product. 1 , the AlCl 3 The mole fraction is 0.67.

[0057] Under vigorous stirring, 27.0 g of 1,3-propane sultone was dissolved in ethyl acetate, and then 20.2 g of triethylamine was added at 50 ° C. The precipitated solid was filtered out and washed three times with ethyl acetate, and then dried at 100 ° C for 2 hours to obtain a white powder solid. Continue to dissolve in a small amount of water, add equimolar hydrochloric acid at room temperature and stir for 30 minutes, then heat to 90 ° C and continue stirring for 2 hours. Continue to vacuum dry at 90 ° C to obtain a white viscous liquid. Take it into a flask, continue to add about 65.0 g of ferric chloride in batches under high-speed stirring, and react at 100 ° C for 4 hours to obtain a viscous ionic liquid C 2 .

[0058] The ionic liquid C 1 With C 2 After fully mixing at a mass ratio of 8:1, ionic liquid catalyst C was obtained.

[0059] Comparative Example 2

[0060] Take 107.3 g of 1-butyl-3-methylimidazolium chloride and add it to a three-necked flask. Pass N 2 Atmosphere protection. Under high-speed stirring, 169.0 g aluminum chloride was added in batches or at a constant speed in small doses, and 112.4 g liquid paraffin was added at the same time. Stirring was continued for 4 hours, and after standing overnight, a dark brown viscous liquid product was collected, which was recorded as ionic liquid D. The AlCl 3 The mole fraction is 0.67.

[0061] Example 3

[0062] Take 45.7g of hexane and add it into a three-necked flask, keep it at 80℃ and keep it under N 2 Under the protection of the atmosphere, 45.0 g of triethylamine hydrochloride was added. Under high-speed stirring, 96.4 g of aluminum chloride was added to the mixture obtained previously in batches or at a constant speed in small doses. At the same time, 1.4 g of copper chloride was added. After stirring for 3 hours, the mixture was allowed to stand for a long time. A dark brown viscous ionic liquid E was obtained at the lower layer of the product. 1 , the AlCl 3 The mole fraction is 0.68.

[0063] After dissolving 20.5 g of triethylamine in a small amount of ethanol, 30.0 g of 1,4-butane sultone was added dropwise to the triethylamine solution. Stir and reflux at 60 ° C for 24 hours, then remove the ethanol by rotary evaporation under reduced pressure, continue to wash with toluene and ether and vacuum dry. The obtained solid was further dissolved in ethanol, and about 30.0 g of trifluoromethanesulfonic acid was added. Stirring was continued, and condensation reflux was performed at 60 ° C for 6 hours. Then it was washed and purified with toluene and ether, and vacuum dried for 12 hours to finally obtain ionic liquid E 2 .

[0064] The ionic liquid E 1 With E 2 After fully mixing at a mass ratio of 15:1, ionic liquid catalyst E was obtained.

[0065] Example 4

[0066] 24.9 g of dodecyl dimethyl benzyl ammonium chloride and 34.8 g of liquid paraffin were added to a three-necked flask and kept at 60 °C under N 2 Under the protection of the atmosphere, 20.6 g of aluminum chloride was added in batches. After stirring for 4 hours, the mixture was allowed to stand for a long time. A very viscous dark brown ionic liquid F was obtained at the bottom of the product. 1 , the AlCl 3 The mole fraction is 0.68.

[0067] Take 1.1g of aluminum trifluoromethanesulfonate, add about 13.5g of 1-butyl-3-methylimidazolium hexafluorophosphate and continue stirring until uniformly dispersed, and add about 55.0g of trifluoromethanesulfonic acid. At room temperature, mix thoroughly to obtain a viscous liquid F 2 .

[0068] The ionic liquid F 1 With suspended liquid F 2 After fully mixing at a mass ratio of 5:1, ionic liquid catalyst F was obtained.

[0069] Example 5

[0070] 22.9 g of hexadecyltrimethylammonium chloride, 34.6 g of liquid paraffin and 24.5 g of ferric chloride were added to a three-necked flask in sequence. 2 Under the protection of atmosphere, the mixture was stirred for 3 hours and then allowed to stand for a long time. A very viscous dark brown ionic liquid G was obtained at the bottom of the product. 1 After cooling to room temperature, it becomes solid. The FeCl 3 The mole fraction is 0.73.

[0071] 14.6 g of isobutylamine and 27.0 g of 1,3-propane sultone were placed in a flask and heated at 50 °C for 6 hours with stirring and reflux. The solid was then filtered out after cooling to room temperature, washed with toluene and ether, and vacuum dried for 24 hours to obtain a white powdery solid. The solid was dissolved in toluene and an appropriate amount of phosphoric acid was added dropwise. The solid was stirred at 60 °C for 24 hours. After cooling, the lower layer product was separated and washed with a solvent, separated by rotary evaporation, and vacuum dried to obtain the final yellow viscous ionic liquid G. 2 .

[0072] The ionic liquid G 1 With G 2 After fully mixing at a mass ratio of 10:1, ionic liquid catalyst G was obtained.

[0073] Example 6

[0074] 20.6 g of benzyltrimethylammonium chloride and 40.7 g of liquid paraffin were added to a three-necked flask in sequence, and the flask was kept at 60°C under N 2 Under the protection of the atmosphere, 31.5 g of aluminum chloride was added to the above mixture in batches or at a constant speed. After stirring for 3 hours, the mixture was allowed to stand for a long time. A black liquid ionic liquid H 1 , the AlCl 3 The mole fraction is 0.68.

[0075] Take 0.8g of copper trifluoromethanesulfonate and add about 16.9g of 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide and continue stirring until uniformly dispersed, and then continue to add about 70.8g of 1,1,2,2-tetrafluoroethylsulfonic acid. Mix thoroughly at room temperature to obtain a viscous liquid H 2 .

[0076] The ionic liquid H 1 With suspended liquid H 2 After fully mixing at a mass ratio of 8:1, the ionic liquid catalyst H was obtained.

[0077] Example 7

[0078] Add 25.0 g of tetramethylammonium chloride and 40.0 g of liquid paraffin into a three-necked flask, keep it at 70 °C and keep it under N 2 Under the protection of the atmosphere, 65.0 g of aluminum chloride was added to the above mixture in batches or at a constant speed. After stirring for 3 hours, the mixture was allowed to stand for a long time. The lower layer of the product was a black liquid ionic liquid I. 1 After cooling to room temperature, it becomes solid. The AlCl 3 The mole fraction is 0.68.

[0079] 24.6 g of allyltrimethylammonium chloride and 74.1 g of liquid paraffin were added to the flask in sequence, and the flask was kept at 60 °C and N 2 Under the protection of the atmosphere, 50.0 g of aluminum chloride was added to the prepared mixture in batches or at a constant speed in small doses, and 75.0 g of toluenesulfonic acid was added after stirring evenly. Stirring was continued for 6 hours and then allowed to stand fully. The lower layer of the product was a black liquid ionic liquid I. 2 After cooling to room temperature, it partially solidifies. 3 The mole fraction is 0.67.

[0080] The ionic liquid I 1 With ionic liquid I 2 After being fully mixed at a mass ratio of 1:1 at 60° C., an ionic liquid catalyst I was obtained.

[0081] Example 8

[0082] Take 89.3g of n-octane and add it into a three-necked flask, keep it at 80℃ and keep it under N 2 Under the protection of atmosphere, 47.8 g of triethylamine hydrochloride was added. Under high-speed stirring, 90.0 g of aluminum chloride was added to the mixture obtained previously in batches or at a constant speed in small doses. At the same time, 1.60 g of cuprous chloride was added. After stirring for 3 hours, the mixture was allowed to stand for a long time. A dark brown viscous ionic liquid J was obtained at the bottom of the product. 1 .

[0083] 24.1 g of dimethyl dioctadecyl ammonium chloride and 54.7 g of liquid paraffin were added to the flask in sequence, and the mixture was kept at 60 °C under N 2 Under the protection of the atmosphere, add 12.1g of aluminum chloride in small doses or at a constant speed to the prepared mixture, stir evenly, and then add 72.4g of 1,1,2,2-tetrafluoroethanesulfonic acid. Continue stirring for 6 hours and let it stand for a long time. The lower layer of the product is a brown liquid ionic liquid J. 2 .

[0084] The ionic liquid J 1 With ionic liquid J 2 After fully mixing at a mass ratio of 1:1 at 60° C., ionic liquid catalyst J was obtained.

[0085] Example 9

[0086] Add 25.7 g of tetraethylammonium bromide and 75.3 g of liquid paraffin into a three-necked flask, keep it at 60 °C, and introduce N 2 Atmosphere protection. Under high-speed stirring, add 56.0 g of aluminum chloride in batches or at a constant speed. Continue stirring for 3 hours to form a homogeneous phase. A black liquid ionic liquid K is obtained at the bottom of the product. 1 , the AlCl 3The mole fraction is 0.76.

[0087] 14.6 g of isobutylamine and 30.0 g of 1,4-butane sultone were placed in a flask and heated, stirred and refluxed at 50 ° C for 6 hours, then cooled to room temperature and filtered out the solid, washed with toluene and ether, and vacuum dried for 24 hours to obtain a white powdery solid. The above solid was dissolved in toluene and a slightly excess of trifluoroacetic acid was added dropwise, and continued to be stirred at 60 ° C for 24 hours. After cooling, the lower layer product was separated, and continued to be washed with a solvent, separated by rotary evaporation and vacuum dried to obtain the final viscous ionic liquid K 2 .

[0088] The ionic liquid K 1 With K 2 After fully mixing at a mass ratio of 10:1, the ionic liquid catalyst K was obtained.

[0089] Example 10

[0090] Add 31.0 g of tetrabutylammonium bromide and 75.7 g of liquid paraffin into a three-necked flask, keep it at 60 °C, and introduce N 2 Atmosphere protection. Under high-speed stirring, add 31.3 g of aluminum chloride in small doses in batches or at a constant speed. Continue stirring for 3.5 hours to form a homogeneous phase, and obtain a black liquid ionic liquid L in the lower layer of the product. 1 , and becomes solid after cooling to below room temperature. 3 The mole fraction is 0.70.

[0091] Under vigorous stirring, 27.0 g of 1,3-propane sultone was dissolved in ethyl acetate, and then 20.2 g of triethylamine was added at 50 ° C. The precipitated solid was filtered out and washed three times with ethyl acetate, and then dried at 100 ° C for 2 hours to obtain a white powder solid. Continue to dissolve in a small amount of water, and stir for 30 minutes after adding equimolar hydrochloric acid at room temperature, and then heat to 90 ° C and continue stirring for 2 hours. Continue to vacuum dry at 90 ° C to obtain a white viscous liquid. Take it into a flask, continue to add about 54.6 g of zinc chloride in batches under high-speed stirring, and react at 100 ° C for 4 hours to obtain a viscous ionic liquid L 2 .

[0092] The ionic liquid L 1 With L 2 After fully mixing at a mass ratio of 6:1, the ionic liquid catalyst L was obtained.

[0093] Embodiment 11

[0094] Take 52.1g of n-dodecane and add it into a three-necked flask, keep it at 80℃ and N 2Under the protection of atmosphere, 20.8 g of triethylamine hydrochloride was added. 45.4 g of aluminum chloride and 1.9 g of cuprous chloride were first mixed evenly, and then the mixture obtained before was added in batches or at a constant speed in small doses. The whole process was carried out under high-speed stirring. After stirring for 6 hours, the mixture was allowed to stand for a long time. A black liquid ionic liquid M was obtained at the bottom of the product. 1 , the AlCl 3 The mole fraction is 0.69.

[0095] Add 24.4 g of methyl trioctyl ammonium chloride and 53.4 g of liquid paraffin into a three-necked flask, keep it at 60 °C and keep it under N 2 Under the protection of the atmosphere, 16.3 g of aluminum chloride was added to the prepared mixture in batches or at a constant speed in small doses. After thorough mixing, 81.4 g of trifluoromethanesulfonic acid was added. Stirring was continued for 5 hours and then allowed to stand. A brown liquid ionic liquid M was obtained at the lower layer of the product. 2 .

[0096] The ionic liquid M 1 With ionic liquid M 2 The ionic liquid catalyst M was obtained by fully mixing at a mass ratio of 1:1 at 60°C.

[0097] Example 12

[0098] 30.9 g of benzyltributylammonium chloride and 90.6 g of liquid paraffin were added to a three-necked flask in sequence, and the flask was kept at 60 °C under N 2 Under the protection of the atmosphere, 30.1 g of aluminum chloride was added to the prepared mixture in batches or at a constant speed. After stirring for 5.5 hours, the mixture was allowed to stand for a long time. The lower layer of the product was a dark brown liquid ionic liquid N. 1 , the AlCl 3 The mole fraction is 0.70.

[0099] After dissolving 20.5 g of triethylamine in a small amount of ethanol, 30.0 g of 1,4-butane sultone was added dropwise to the triethylamine solution. Stir and reflux at 60 ° C for 24 hours, then remove the ethanol by rotary evaporation under reduced pressure, continue to wash with toluene and ether and vacuum dry. The obtained solid was further dissolved in ethanol, and an appropriate amount of sulfuric acid was added. Continue stirring and condense and reflux at 60 ° C for 6 hours. Then wash and purify with toluene and ether, and continue vacuum drying for 12 hours to finally obtain ionic liquid N 2 .

[0100] The ionic liquid N 1 With N 2 After fully mixing at a mass ratio of 10:1, ionic liquid catalyst N was obtained.

[0101] Comparative Example 3

[0102] Add 23.3 g of 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt into a three-necked flask, keep it at 90°C and keep it under N 2 Under the protection of the atmosphere, add 15.4g of aluminum chloride in batches or at a constant speed. Continue stirring for 4-13 hours and then let it stand for a long time. The lower layer of the product is a black liquid ionic liquid Q. The ionic liquid contains AlCl 3 The mole fraction is 0.68.

[0103] Examples 13-20

[0104] A certain amount of benzene is added to a three-necked flask and heated to the reaction temperature. Under appropriate speed stirring, a certain amount of ionic liquid is added and evenly mixed. This group of examples uses ionic liquids A, C, and E. Then a certain amount of alkylating agent is taken so that the molar ratio of benzene to normal olefins in the alkylating agent is 9. This group of examples uses hexadecene, tetradecene, and C 12+ Oil. Alkylating agent C 12+ Oil refers to C 12+ The Fischer-Tropsch synthesis treated oil of the fraction section has a typical composition including: 25%-35% normal olefins, 0.02%-1% oxygen-containing compounds, 5%-10% normal alkanes, 40%-60% isoalkene and 1%-10% aromatics. The alkylating agent is slowly added dropwise to the reaction flask at a uniform rate. After the reaction is completed, the final product is separated by standing for a long time to obtain an upper organic phase and a lower ionic liquid. The ionic liquid after sedimentation separation can be regenerated and recycled. The upper organic phase liquid is sampled and analyzed by gas chromatography-mass spectrometry. Other specific raw material ratios and reaction conditions are summarized in Table 1.

[0105] Comparative Examples 4-8

[0106] The same specific steps as in Examples 13-20 were used, the catalysts used were ionic liquids B and D, and the alkylating agents used were hexadecene, dodecene and C 12+ Oil, other specific raw material ratios, reaction conditions and reaction results are shown in Table 1.

[0107] By comparing Examples 13-18 and Comparative Examples 4-8, it can be seen that the conversion rate and selectivity of ionic liquids A, C, and E as catalysts for the alkylation of long-chain normal olefins are higher than those of ionic liquids B and D at the same catalyst dosage and reaction temperature. The complete conversion of dodecene by ionic liquid D requires a higher reaction temperature and a much higher dosage of ionic liquid catalyst than that of the previous examples. 12+ In the catalytic reaction of oil, ionic liquid E also achieved better conversion rate and selectivity than ionic liquid D.

[0108] Table 1

[0109]

[0110]

[0111] Examples 21-26

[0112] Ionic liquid E was used as a catalyst, the reaction temperature was 60°C, and the specific steps were the same as those in Example 13-20. The alkylating agent raw material was C 12+ The specific composition of the mixture after the oil and the long-chain alkene are compounded and adjusted is shown in Table 2. Other reaction conditions and reaction results are shown in Table 3. From the results in the table, it can be seen that the ionic liquid E is used as a catalyst for the synthesis of long-chain alkylbenzenes, especially it can tolerate at least 15.18% of isomeric hydrocarbons, 2.72% of aromatic hydrocarbons and 0.23% of oxygen-containing compounds, and its normal olefin conversion rate can still be maintained at more than 98%, and the monoalkylbenzene conversion rate is close to 70%. This shows that the ionic liquid catalyst of the present invention can adapt to alkylating agent raw materials with complex component composition.

[0113] Table 2

[0114]

[0115] Table 3

[0116]

[0117]

[0118] Examples 27-30

[0119] Ionic liquids K and L were used as catalysts for the synthesis of long-chain alkylbenzenes. Hexadecene and C 12+ Oil. The specific steps are the same as those of Examples 13-20. After the synthesis reaction is completed, the upper organic phase and the lower ionic liquid are obtained after a long period of static separation. The ionic liquid after sedimentation separation is directly used as a catalyst for the next reaction with a fresh alkylating agent. The hexadecene experiment was repeated twice. 12+ The oil experiment was repeated once more. Other experimental conditions and results are shown in Table 4. O / m MX It refers to the mass of normal olefins in the alkylating agent that can be accumulated and converted after multiple cycles of reaction of metal halide in unit mass of ionic liquid. This ratio can comprehensively show the activity and stability of the ionic liquid.

[0120] Comparative Examples 9-10

[0121] Ionic liquid Q was used as a catalyst for the synthesis of long-chain alkylbenzenes, and hexadecene and C 12+The specific steps are the same as those of Examples 27-30. Other experimental conditions and results are shown in Table 4.

[0122] Table 4

[0123] Serial number catalyst Alkylating agent Reaction temperature (℃) Total yield % <![CDATA[Circular cumulative m O / m MX > Embodiment 27 K Hexadecene 40 55.9 100.0 Embodiment 28 K <![CDATA[C 12+ Oil]]> 60 60.3 6.1 Embodiment 29 L Hexadecene 40 56.3 94.3 Embodiment 30 L Hexadecene 60 56.4 87.5 Comparative Example 9 Q Hexadecene 60 38.4 62.1 Comparative Example 10 Q <![CDATA[C 12+ Oil]]> 60 40.1 4.5

[0124] Comparison of Examples 27-30 with Comparative Examples 9-10 shows that the total yield and cumulative cycle m of ionic liquids K and L as catalysts O / m MX All of them are higher than the results of ionic liquid Q. This shows that the ionic liquid catalyst in the present invention has better catalytic performance and stability in the synthesis reaction of long-chain alkylbenzene.

Claims

1. An ionic liquid catalyst, characterized in that The ionic liquid catalyst is a mixed polyacidic ionic liquid catalyst, which comprises two ionic liquids of different properties, wherein the cation of at least one ionic liquid is derived from the hydrogen halide or quaternary ammonium salt of amine substituted by alkyl, and the other ionic liquid is an acidic ionic liquid.

2. The ionic liquid catalyst according to claim 1, characterized in that The general structural formula of the cation is [R n NH 4-n ] + , wherein R represents a hydrocarbon group, and n=1-4.

3. The ionic liquid catalyst according to claim 2, characterized in that The cation is derived from at least one of trimethylamine hydrochloride, triethylamine hydrochloride, dodecyldimethylbenzylammonium chloride, hexadecyltrimethylammonium chloride, benzyltrimethylammonium chloride, tetramethylammonium chloride, tetraethylammonium bromide, tetrabutylammonium bromide, benzyltributylammonium chloride, allyltrimethylammonium chloride, dimethyldioctadecylammonium chloride and methyltrioctylammonium chloride; and / or, The anions in the cation corresponding to the ionic liquid are selected from one or a combination of halide ion, hexafluorophosphate, trifluoromethanesulfonate, bis(trifluoromethylsulfonyl)imide ion, methanesulfonate, benzenesulfonate, hydrogen sulfate, dihydrogen phosphate, chloroaluminate, chloroferrate and toluenesulfonate.

4. The ionic liquid catalyst according to claim 1, characterized in that The acidic ionic liquid is selected from at least one of quaternary ammonium salt type diacidic ionic liquids, ionic liquids of ammonium salt cations added with auxiliary strong acidic substances, and ionic liquids of imidazole cations added with auxiliary strong acidic substances.

5. The ionic liquid catalyst according to claim 1, characterized in that The ionic liquid catalyst further comprises an auxiliary agent, which is a metal compound and / or a strong acidic substance. The metal compound is selected from one or a combination of aluminum chloride, ferric chloride, cupric chloride, cuprous chloride, zinc chloride, aluminum trifluoromethanesulfonate and copper trifluoromethanesulfonate; and the strong acidic substance is selected from at least one of trifluoromethanesulfonic acid, 1,1,2,2-tetrafluoroethylsulfonic acid, toluenesulfonic acid and trifluoroacetic acid.

6. A method for preparing an ionic liquid catalyst, characterized in that: The preparation method comprises mixing an ammonium salt cationic ionic liquid and an acidic ionic liquid in proportion, and uniformly combining them by sufficient stirring to form a mixed polyacidic ionic liquid catalyst as claimed in any one of claims 1 to 5 having a synergistic catalytic effect.

7. The preparation method according to claim 6, characterized in that: The mixing mass ratio of the ammonium salt cationic ionic liquid to the acidic ionic liquid is 1-20.

8. The preparation method according to claim 6, characterized in that: The preparation steps of the ammonium salt cationic ionic liquid are as follows: First, add the ammonium salt precursor salt into a dry reactor and operate in an anhydrous and oxygen-free environment; then add a co-solvent to fully dissolve the precursor salt, and heat the reactor to a constant temperature of 10-100°C for reaction; at an appropriate stirring speed, slowly add anhydrous metal salts in batches to ensure uniform mixing; as needed, continue to add other metal compounds or strong acidic substances; finally, after stirring to a homogeneous phase, stand and separate, collect the lower layer of viscous liquid, and complete the preparation of ammonium salt cationic ionic liquid.

9. The preparation method according to claim 8, characterized in that: The co-solvent is selected from liquid paraffin or medium-long chain normal alkanes with a carbon number ranging from 6 to 18.

10. A method for synthesizing long-chain alkylbenzene, characterized in that: A mixed polyacidic ionic liquid catalyst prepared by the mixed polyacidic ionic liquid catalyst described in any one of claims 1 to 5 or the preparation method described in any one of claims 6 to 9; the specific synthesis steps are as follows: Add an appropriate amount of benzene into the reaction vessel and heat to the reaction temperature; Add the mixed polyacidic ionic liquid catalyst at an appropriate stirring speed to fully mix it with benzene; gradually adding the alkylating agent dropwise at a certain rate; The reaction temperature is maintained to continue the reaction. After the reaction is completed, stirring is stopped and the reaction mixture is taken out; After standing and separating, the ionic liquid catalyst in the lower layer is recovered for subsequent recycling.

11. The method according to claim 10, characterized in that The alkylating agent is a mixture of one or more combinations of C10-C22 long straight-chain olefins, or a mixed olefin raw material containing a certain amount of other types of components or impurities, and the mixed olefin raw material is an olefin component in a Fischer-Tropsch synthesis product, a hydrocarbon-olefin mixed fraction, or other petrochemical products; and / or, The molar ratio of benzene to normal olefins in the alkylating agent is 5-30, and the molar ratio of the ionic liquid catalyst to normal olefins in the alkylating agent is 0.01-0.5; and / or, The reaction temperature is 10-80° C., and the dropping rate of the alkylating agent is 0.1-6 g / min.

12. An application of an ionic liquid catalyst, characterized in that: The ionic liquid catalyst is a mixed polyacidic ionic liquid catalyst as described in any one of claims 1 to 5 or a mixed polyacidic ionic liquid catalyst prepared by the preparation method as described in any one of claims 6 to 9, The mixed polyacidic ionic liquid catalyst is applied to Friedel-Crafts alkylation reaction to synthesize long-chain alkylbenzene or other alkylbenzene products of the same type.

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