阅读说明：本技术 磺酸功能化的咪唑离子液体催化剂及其制备方法和应用 (Sulfonic acid functionalized imidazole ionic liquid catalyst and preparation method and application thereof ) 是由 冯刚 张雪 张荣斌 于 2021-09-03 设计创作，主要内容包括：本发明公开了磺酸功能化的咪唑离子液体催化剂及其制备方法和应用。主要解决以往技术中制备磺酸功能化咪唑离子液体的技术问题。本发明通过两步合成的方法将咪唑与烷基磺酸在35～300℃下加热；再将酸加入到上一步骤中,在30～330℃下充分反应,经过提纯处理得到的目标产物,该方案较好的解决了上述技术问题。所述的磺酸功能化咪唑离子液体包括咪唑、烷基磺酸和酸根离。本发明设计的离子液体催化剂应用于酸或酸酐与醇的酯化反应中,具有较高的催化活性、高稳定性、反应速率快且副产物少,有利于工业化应用。(The invention discloses a sulfonic acid functionalized imidazole ionic liquid catalyst, and a preparation method and application thereof. Mainly solves the technical problem of preparing sulfonic acid functionalized imidazole ionic liquid in the prior art. Heating imidazole and alkyl sulfonic acid at 35-300 ℃ by a two-step synthesis method; and adding acid into the previous step, fully reacting at 30-330 ℃, and purifying to obtain a target product. The sulfonic acid functionalized imidazole ionic liquid comprises imidazole, alkyl sulfonic acid and acid radical ions. The ionic liquid catalyst designed by the invention is applied to the esterification reaction of acid or anhydride and alcohol, has higher catalytic activity, high stability, high reaction rate and less byproducts, and is beneficial to industrial application.)

1. Sulfonic acid functionalized imidazole ionic liquid catalyst, which is characterized in that: the catalyst comprises imidazole, alkyl sulfonic acid and acid radical ions, the structure of the catalyst is shown as the formula (I),

in the formula, m is 2-10, and imidazole is N-methylimidazole; x^-Is an acid radical ion;

the imidazole accounts for 30 to 60 percent of the total weight in percentage by weight; the alkyl sulfonic acid accounts for 35 to 60 percent of the total weight; the acid radical ion accounts for 1 to 25 percent of the total weight.

2. The sulfonic acid functionalized imidazole ionic liquid catalyst of claim 1, wherein: the pH value of the catalyst is 1.0-3.0; the conductivity is 0.23-1.48S/m; the viscosity is 350 to 750 mPas.

3. The process for the preparation of sulfonic acid functionalized imidazole ionic liquid catalyst according to claim 1 or 2, characterized by the following steps:

s1, synthesis of ionic liquid precursor: dissolving imidazole and alkyl sulfonic acid in a solvent A according to a molar ratio of 1: 1.0-3.0, gradually heating to 35-300 ℃, and stirring for 1-48 h, wherein an ionic liquid precursor is a cation of an ionic liquid;

s2, ionic liquid precursor treatment: washing the ionic liquid cation obtained in the step S1 with a solvent A at normal temperature, and drying at 60-120 ℃ for 1-24 h;

s3, mixing the ionic liquid precursor treated in the step S2 and acid in a molar ratio of 1: 1.0-3.5, stirring at 30-330 ℃ for 2-48 h, and evaporating at 50-150 ℃ for 1-3 h to obtain the sulfonic acid functionalized imidazole ionic liquid.

4. The method of preparing sulfonic acid functionalized imidazole ionic liquid catalyst according to claim 3, characterized in that: the solvent A is at least one of toluene, diethyl ether and ethyl acetate.

5. The method of preparing sulfonic acid functionalized imidazole ionic liquid catalyst according to claim 3, characterized in that: the imidazole is N-methylimidazole, and the alkyl sulfonic acid is at least one of butane sulfonic acid, pentane sulfonic acid, hexane sulfonic acid, heptane sulfonic acid, octane sulfonic acid, nonane sulfonic acid, decane sulfonic acid, undecane sulfonic acid and dodecane sulfonic acid; the acid is at least one of hydrochloric acid, benzoic acid, lactic acid, acetic acid, sulfurous acid, and sulfuric acid.

6. The method of preparing sulfonic acid functionalized imidazole ionic liquid catalyst according to claim 3, characterized in that: in the step S1, the molar ratio of imidazole to alkyl sulfonic acid is 1: 1.02-1.9, the temperature of the ionic liquid precursor is 40-200 ℃, and the stirring time is 2-10 h; in the step S3, the molar ratio of the ionic liquid precursor to the acid is 1 to (1.02-1.8), the temperature of the ionic liquid precursor and the acid is 40-230 ℃, and the stirring time is 2-12 h.

7. Use of the sulfonic acid functionalized imidazole ionic liquid catalyst according to claim 1 or 2, characterized in that: the sulfonic acid functionalized imidazole ionic liquid catalyst is used for catalyzing esterification reaction, and specifically comprises the following components:

taking the sulfonic acid functionalized imidazole ionic liquid as a catalyst, taking a substance containing acid anhydride or acid and alcohol as a raw material, contacting the raw material with the ionic liquid catalyst, and carrying out a contact reaction on the raw material and the ionic liquid catalyst under the reaction conditions of a reaction temperature of 80-240 ℃, a reaction time of 1-10 hours and a reaction pressure of 0.05-5 MPa to generate a substance containing ester;

wherein the molar ratio of the acid anhydride or acid to the alcohol is 1: 1.0-15, and the dosage of the ionic liquid catalyst is 0.00001-45 wt% of the total mass of the raw materials.

8. Use of the sulfonic acid functionalized imidazole ionic liquid catalyst according to claim 7, characterized in that: the acid or acid anhydride is at least one of phthalic anhydride, terephthalic acid, naphthalene dicarboxylic acid and acetic acid.

9. Use of the sulfonic acid functionalized imidazole ionic liquid catalyst according to claim 7, characterized in that: the alcohol is at least one of methanol, ethanol, ethylene glycol, n-butanol, propylene glycol and isooctyl alcohol.

10. Use of the sulfonic acid functionalized imidazole ionic liquid catalyst according to claim 7, characterized in that: the molar ratio of the acid anhydride or acid to the alcohol is 1 to (2.1-8), and the dosage of the ionic liquid is 0.0001-18% of the total mass of the raw materials.

Technical Field

The invention belongs to the technical field of liquid catalysts, and particularly relates to a sulfonic acid functionalized imidazole ionic liquid catalyst, and a preparation method and application thereof.

Background

Esters are important organic compounds and are commonly used as organic solvents and as starting materials for organic synthesis. The traditional synthesis method generally adopts acid and alcohol as raw materials, concentrated sulfuric acid or titanium substances as catalysts, and the raw materials are heated for a long time and directly esterified and synthesized. Concentrated sulfuric acid used as a catalyst is low in price, and meanwhile, the concentrated sulfuric acid has esterification, dehydration and oxidation effects, so that a series of side reactions occur, a reaction product contains a small amount of ether, sulfate and hydroxyl compounds, and the product refining and raw material recycling are difficult, so that the industrial application of the concentrated sulfuric acid is limited. The titanium catalyst generates few byproducts in the catalytic esterification process but has overhigh energy consumption, thereby having certain difficulty for industrial production. Therefore, it is important to develop an environmentally friendly esterification catalyst which is stable and has high catalytic activity and low price. At present, ionic liquid with acidity is widely researched by scientists as an esterification catalyst.

The ionic liquid is low-temperature molten salt formed by anions and cations, and corresponding anions and cations can be selected or cations with specific functional groups can be designed according to targets, so that the ionic liquid is various. The ionic liquid has wide liquid temperature range, better thermal stability and chemical stability (the operating temperature range can reach minus 40 ℃ to 300 ℃), low vapor pressure, difficult volatilization, good stability and better solubility for inorganic matters and organic matters, and can be used as an environment-friendly solvent and a catalyst, thereby becoming a research hotspot for catalyzing acid-alcohol esterification reaction. The sulfonic acid group-containing organic acid has strong acidity and can replace concentrated sulfuric acid to be used as the sulfonic acid group-containing organic acidAcid catalyst and is less corrosive than concentrated sulfuric acid. Therefore, the sulfonic acid group is introduced into the ionic liquid to synthesize sulfonic acid functionalized ionic liquid is an important way for increasing the acidity of the ionic liquid, and the sulfonic acid group introduced ionic liquid has high stability, good catalytic activity and high reuse rate.

In the current research on sulfonic acid functionalized imidazole ionic liquid,the preparation of an acidic ionic liquid containing an imidazole ring introduced with a sulfonic acid group, such as a hydrogenated acrylic acid with a high molar by a branched acidic ionic liquid, journal of Molecular Catalysis A, Chemical 212(2004)71-75, is proposed to show that the chain length of the alkyl group connected to the cation of the ionic liquid and the other N has a great influence on the conversion and selectivity of the Esterification reaction of fatty acid and olefin. Cole et al (Novel Bronsted acidic ionic liquids and the use of dual solvent-catalysts, J.Am.chem.Soc.2002, 124, 5962-5963) have reported for the first time the synthesis of functionalized ionic liquids with sulfonic acid groups on imidazole or quaternary phosphonium cations, and such Bronsted acidic ionic liquids can be applied to acid-catalyzed reactions such as esterification and pinacol rearrangement. In patent CN101456844, it is reported that the sulfonic acid type imidazole ionic liquid containing N- (methyl, ethyl, propyl, butyl, amyl) alkane sulfonic acid imidazole ionic liquid is synthesized at 60-90 ℃, and is used in esterification reaction of polybasic acid and alcohol, and the result shows that the yield of the esterification reaction is close to 100%, and is obviously improved compared with the activity of the traditional catalyst. In patent CN 10779336, it is reported that [ MIMPS ] is synthesized at 70-80 DEG C]⁺[CH₃SO₃]Sulfonic acid type imidazole ionic liquids exhibit high stability and catalytic activity in the synthesis reaction of xanthone. Therefore, the sulfonic acid functionalized imidazole ionic liquid has good catalytic performance and can be widely applied. The sulfonic acid with longer alkyl side chain is introduced into the method, and the method is applied to esterification reaction, and shows higher catalytic activity of the sulfonic acid functionalized imidazole ionic liquid.

Disclosure of Invention

Aiming at the defects and problems in the prior art, the invention aims to provide a sulfonic acid functionalized imidazole ionic liquid catalyst, and a preparation method and application thereof.

The invention is realized by the following technical scheme:

the invention provides a sulfonic acid functionalized imidazole ionic liquid catalyst, which aims to solve the technical problem of sulfonic acid functionalized ionic liquid which cannot be provided by the prior art.

The sulfonic acid functionalized imidazole ionic liquid catalyst comprises imidazole, alkyl sulfonic acid and acid radical ions, and the structure of the catalyst is shown as the formula (I),

in the formula, m is 2-10, and imidazole is N-methylimidazole; x^-Is an acid radical ion;

the imidazole accounts for 30 to 60 percent of the total weight in percentage by weight; the alkyl sulfonic acid accounts for 35 to 60 percent of the total weight; the acid radical ion accounts for 1 to 25 percent of the total weight.

The pH value of the sulfonic acid functionalized imidazole ionic liquid in the scheme is 1.0-3.0; the conductivity is 0.23-1.48S/m; the viscosity is 350 to 750 mPas.

The second aspect of the present invention provides a preparation method of the sulfonic acid functionalized imidazole ionic liquid, which can be used for producing sulfonic acid functionalized imidazole ionic liquid catalyst, and overcomes the problems of complicated synthesis of ionic liquid and single kind of ionic liquid in the prior art.

According to the preparation method of the sulfonic acid functionalized imidazole ionic liquid catalyst, the sulfonic acid functionalized imidazole ionic liquid is prepared through the following steps:

s1: preparing an ionic liquid precursor: dissolving imidazole and alkyl sulfonic acid in a solvent A according to a molar ratio of 1: 1.0-3.0, gradually heating to 35-300 ℃, and stirring for 1-48 h, wherein an ionic liquid precursor is a cation of an ionic liquid;

s2: treating an ionic liquid precursor: washing the ionic liquid cation obtained in the step S1 with a solvent A at normal temperature, and drying at 60-120 ℃ for 1-24 h;

s3: mixing the ionic liquid precursor treated in the step S2 and acid in a molar ratio of 1: 1.0-3.5, stirring at 30-330 ℃ for 2-48 h, and evaporating at 50-150 ℃ for 1-3 h to obtain the sulfonated ionic liquid.

In the scheme, the solvent A is at least one of toluene, diethyl ether and ethyl acetate. The imidazole is at least one of N-methylimidazole, alkyl sulfonic acid butane sulfonic acid, sulfonic acid pentane, sulfonic acid hexane, sulfonic acid heptane, sulfonic acid octane, sulfonic acid nonane, sulfonic acid decane, sulfonic acid undecane and sulfonic acid dodecane. The acid is at least one of hydrochloric acid, benzoic acid, lactic acid, acetic acid, sulfurous acid, and sulfuric acid.

The preferable range of the material ratio is as follows: the molar ratio of the N-methylimidazole to the alkyl sulfonic acid is 1: 1.02-1.9, and the molar ratio of the ionic liquid precursor to the acid is 1: 1.02-1.8.

The temperature for synthesizing the ionic liquid precursor in the step S1 is 40-200 ℃, the stirring time is 2-10 h, the temperature for reacting the ionic liquid precursor with the acid in the step S3 is 40-230 ℃, and the stirring time is 2-12 h.

In order to overcome the defects of more by-products, difficult synthesis, difficult separation and the like of the traditional catalyst in the esterification reaction, the invention provides the application of the sulfonic acid functionalized imidazole ionic liquid catalyst in the esterification reaction, and the imidazole ionic liquid catalyst in the esterification reaction has the advantages of strong acidity, high stability, high catalytic activity, simple synthesis and the like. The method comprises the following specific steps:

the method comprises the steps of taking a substance containing acid anhydride or acid and alcohol as a raw material, wherein the molar ratio of the acid anhydride or acid to the alcohol is 1: 1.0-15, contacting the acid anhydride or a mixture of the acid and the alcohol with an ionic liquid catalyst, wherein the dosage of the ionic liquid catalyst is 0.00001-45 wt% of the total mass of the acid or acid anhydride and the alcohol, and the ionic liquid catalyst is contacted and reacted with the ionic liquid catalyst under the reaction conditions that the reaction temperature is 80-240 ℃, the reaction time is 1-10 hours, and the reaction pressure is 0.05-5 MPa to generate the substance containing ester.

In the above scheme, the acid or acid anhydride is at least one of phthalic anhydride, terephthalic acid, naphthalene dicarboxylic acid and acetic acid. The alcohol is at least one of methanol, ethanol, ethylene glycol, n-butanol, propylene glycol and isooctyl alcohol. The molar ratio of the acid to the alcohol is preferably 1 to (1.1-8), and the dosage of the ionic liquid is preferably 0.0001-18% of the total mass of the acid and the alcohol.

Compared with the prior art, the invention has the beneficial effects that:

(1) the sulfonic acid functionalized imidazole ionic liquid catalyst is synthesized by a two-step method, the catalyst contains 35-60% of alkyl sulfonic acid by mass, and the pH value of the ionic liquid catalyst is 1.0-3.0; the conductivity is 0.23-1.48S/m; the viscosity is 350 to 750 mPas.

(2) The preparation method of the sulfonic acid functionalized imidazole ionic liquid catalyst provided by the invention can be used for producing the sulfonated imidazole ionic liquid catalyst, and overcomes the problems of complexity and single type of ionic liquid in the prior art for producing the ionic liquid.

(3) The sulfonic acid functionalized imidazole ionic liquid catalyst and the preparation method thereof can be used in the generation field of esterification reaction, and improve the conversion rate and selectivity of esterification reaction raw materials and the stability of the catalyst.

Detailed Description

The present invention will be further described with reference to the following examples.

[ example 1 ]

1. Preparing an ionic liquid precursor: dissolving N-methylimidazole and hexane sulfonate in a molar ratio of 1: 1.5 in ethyl acetate solvent, gradually heating to 150 ℃, stirring for 14h, washing with ethyl acetate after the reaction is finished to remove unreacted materials, and drying in vacuum at 80 ℃ for 8 h.

2. Preparation of ionic liquid: mixing the washed ionic liquid precursor and acetic acid in a molar ratio of 1: 1.5, stirring at 100 ℃ for 24h, and evaporating at 120 ℃ for 2h after the reaction is finished to obtain yellow viscous liquid.

The sulfonic acid functionalized imidazole ionic liquid catalyst contains 35% of N-methylimidazole, 60% of hexane sulfonate and 5% of acetate by mass; the ionic liquid catalyst has an electric pH of 2.5 and an electric conductivity of 0.23S/m; the viscosity was 355 mPas.

[ example 2 ]

1. Preparing an ionic liquid precursor: dissolving N-methylimidazole and pentane sulfonate in a molar ratio of 1: 1.7 in a solvent of toluene, gradually heating to 300 ℃, stirring for 10 hours, washing with toluene after the reaction is finished to remove unreacted materials, and drying in vacuum for 24 hours at 60 ℃.

2. Preparation of ionic liquid: mixing the washed ionic liquid precursor and sulfurous acid in a molar ratio of 1: 1.2, stirring at 30 ℃ for 48h, and evaporating at 80 ℃ for 1h after the reaction is finished to obtain yellow viscous liquid.

The obtained sulfonic acid functionalized imidazole ionic liquid catalyst contains 35% of N-methylimidazole, 55% of pentane sulfonate and 10% of sulfite by mass; the ionic liquid catalyst has an electric pH value of 1.9 and an electric conductivity of 0.35S/m; the viscosity was 410 mPas.

[ example 3 ]

1. Preparing an ionic liquid precursor: dissolving N-methylimidazole and dodecane sulfonate in a molar ratio of 1: 1.5 in solvent diethyl ether, gradually heating to 120 ℃, stirring for 4 hours, washing with diethyl ether after the reaction is finished to remove unreacted materials, and drying in vacuum at 150 ℃ for 8 hours.

2. Preparation of ionic liquid: mixing the washed ionic liquid precursor and benzoic acid in a molar ratio of 1: 1.08, stirring at 330 ℃ for 2h, and evaporating at 80 ℃ for 3h after the reaction is finished to obtain yellow viscous liquid.

The obtained sulfonic acid functionalized imidazole ionic liquid catalyst contains 35% of N-methylimidazole, 58% of dodecane sulfonate and 7% of benzoate by mass; the ionic liquid catalyst has an electric pH value of 1.6 and an electric conductivity of 0.44S/m; the viscosity was 450 mPas.

[ example 4 ]

1. Preparing an ionic liquid precursor: dissolving N-methylimidazole and butanesulfonic acid in a molar ratio of 1: 1.3 in solvent diethyl ether, gradually heating to 35 ℃, stirring for 8 hours, washing with diethyl ether after the reaction is finished to remove unreacted materials, and drying in vacuum at 80 ℃ for 12 hours.

2. Preparation of ionic liquid: mixing the washed ionic liquid precursor and lactic acid according to the molar ratio of 1: 3.0, stirring at 180 ℃ for 20h, and evaporating at 110 ℃ for 1.5h after the reaction is finished to obtain yellow viscous liquid.

The obtained sulfonic acid functionalized imidazole ionic liquid catalyst contains 47 mass percent of N-methylimidazole, 43 mass percent of butane sulfonic acid and 10 mass percent of lactate; the ionic liquid catalyst has an electric pH of 2.3 and an electric conductivity of 0.65S/m; the viscosity was 500 mPas.

[ example 5 ]

1. Preparing an ionic liquid precursor: dissolving N-methylimidazole and octane sulfonate in a molar ratio of 1: 1.3 in solvent diethyl ether, gradually heating to 155 ℃, stirring for 14 hours, washing with diethyl ether after the reaction is finished to remove unreacted materials, and drying in vacuum at 100 ℃ for 18 hours.

2. Preparation of ionic liquid: mixing the washed ionic liquid precursor and hydrochloric acid in a molar ratio of 1: 2.0, stirring at 220 ℃ for 12h, and evaporating at 50 ℃ for 3h after the reaction is finished to obtain yellow viscous liquid.

The obtained sulfonic acid functionalized imidazole ionic liquid catalyst contains 41% of N-methylimidazole, 55% of octane sulfonate and 4% of hydrogen hydrochloride by mass fraction; the ionic liquid catalyst had an electric pH of 2.4 and an electrical conductivity of 0.62; the viscosity was 550 mPas.

[ examples 6 to 18 ]

The sulfonic acid functionalized imidazole ionic liquid catalyst described in table 1 can be obtained by operating the sulfonic acid functionalized imidazole ionic liquid according to the preparation conditions of table 1 and the steps in the embodiment.

TABLE 1 preparation conditions for examples 6-18

[ examples 19-113 ] sulfonic acid functionalized imidazole ionic liquid catalysts were used for the production of esters.

The esterification product was obtained by evaluating the performance of the catalyst under the reaction conditions shown in table 2, using methanol, ethylene glycol, n-butanol, propylene glycol, isooctanol, phthalic anhydride, terephthalic acid, and naphthalenedicarboxylic acid as raw materials, and the sulfonic acid-functionalized imidazole ionic liquid obtained in examples 1 to 19 as the catalyst.

TABLE 2 reaction conditions for examples 19-113

The invention is not the best known technology.

The foregoing merely represents preferred embodiments of the invention, which are described in some detail and detail, and therefore should not be construed as limiting the scope of the invention. It should be noted that, for those skilled in the art, various changes, modifications and substitutions can be made without departing from the spirit of the present invention, and these are all within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.