Dihydroxyl functionalized super-crosslinked polyion liquid as well as preparation method and application thereof

Abstract

The invention relates to a dihydroxyl functionalized super-crosslinked polyion liquid catalyst as well as a preparation method and application thereof. According to the dihydroxyl functionalized super-crosslinked polyion liquid, on the basis of introduction of dihydroxyl functional groups, different benzene ring structures such as benzene, biphenyl or 1, 3, 5-triphenylbenzene are introduced into a catalyst, and different porous structures are formed. The dihydroxyl functionalized polyion liquid provided by the invention has the advantages of high yield, high specific surface area, strong activity, no need of a cocatalyst and other solvents, high stability and the like in catalysis of synthesis of cyclic carbonate from carbon dioxide and an epoxy compound.

Description

Technical Field

[0001] The invention belongs to the technical field of polyionic liquids and chemical catalysis, and specifically relates to a dihydroxyl functionalized hyper-crosslinked polyionic liquid and its application in catalyzing CO2 and epoxy compounds to prepare important chemical cyclic carbonates. Background Art

[0002] With the rapid development of modern industry, fossil fuels such as coal, oil and natural gas are consumed in large quantities. As a non-renewable energy source, fossil fuels have a large processing consumption. In addition, the pollutants and CO2 emitted by the combustion of these fossil fuels also have a serious impact on society. On the other hand, CO2 is a non-toxic, cheap and abundant carbon resource on the earth. CO2 can be catalytically converted into a variety of chemicals, and the addition reaction of CO2 and epoxide as raw materials to synthesize cyclic carbonates has become one of the most promising and few ways to industrially utilize CO2 due to its low raw material price and 100% atomic utilization rate, which is in line with the development of "green chemistry" and "atom economy".

[0003] At present, although ionic liquids have good catalytic activity when used as homogeneous catalysts to catalyze the CO2 synthesis of cyclic carbonates, there are still some problems, such as complex separation process after catalytic reaction, difficult recovery, poor reusability, etc. Therefore, it is of great significance and value to design heterogeneous catalytic materials derived from ionic liquids with simple synthesis, high catalytic activity and specific functions that are easy to recycle.

[0004] Hypercrosslinked polymers (HCPs) are a class of heterogeneous catalytic materials derived from ionic liquids with specific functions, which have high Brunauer-Emmett-Teller surface area (SBET), unique pore structure and stable physicochemical structure. In addition, HCPs can undergo one-pot Friedel-Crafts reaction and the synthesis process is very simple.

[0005] With the in-depth study of hypercrosslinked polymers, researchers have found that most of the reported HCPs have low catalytic activity in the cycloaddition reaction of CO2 and epoxides, and often require the addition of co-catalysts for activation. Therefore, we need to continuously develop functionalized hypercrosslinked polyionic liquid catalysts with high activity and mild reaction conditions. Summary of the invention

[0006] The purpose of the present invention is to provide a dihydroxyl functionalized hyper-crosslinked polyionic liquid, which has the advantages of high yield, high specific surface area, strong activity, no need for co-catalyst and other solvents, high stability, etc. in catalyzing the synthesis of cyclic carbonates from carbon dioxide and epoxy compounds.

[0007] The technical solution adopted by the present invention is:

[0008] A dihydroxyl functionalized hyper-crosslinked polyionic liquid, which is composed of dihydroxyl active groups and hyper-crosslinked structures; the structure of the polyionic liquid is shown in (I):

[0009]

[0010] in,

[0011] The above-mentioned method for preparing a dihydroxyl functionalized hyper-crosslinked polyionic liquid comprises the following steps:

[0012] 1) benzimidazole and tetrabutylammonium bromide are added to a sodium hydroxide aqueous solution, 2-bromoethanol is added and stirred at room temperature for 3 hours, then deionized water is poured into a beaker, and the mixed solution is extracted with chloroform, the chloroform layer is separated and collected, and finally dried with anhydrous Na2SO4, the organic solvent is removed with a rotary evaporator, and the mixture is dried in a vacuum drying oven to obtain a bromoethanol substitution product;

[0013] 2) weighing the bromoethanol substitution product and 2-bromoethanol into a flask, refluxing at 70° C.-80° C. for 12 hours, washing the obtained solid with anhydrous ethanol 5 times, and vacuum drying to obtain a dihydroxy ionic liquid;

[0014] 3) Adding the dihydroxy ionic liquid, the aromatic compound, anhydrous ferric chloride and dimethoxymethane to the dichloroethane solvent, stirring until the mixture is uniform, and then reflux reacting at 80° C. for 24 hours. After the reaction is completed, a solid substance is obtained, and the solid is washed several times with water and methanol, tetrahydrofuran, and chloroform until the filtrate is clear; and drying is performed to obtain the final product, the dihydroxy functionalized hyper-crosslinked polyionic liquid.

[0015] Furthermore, in the above preparation method, in step 2), the bromoethanol substitution product and 2-bromoethanol are placed in a flask at a molar ratio of 1:1.1.

[0016] Furthermore, in the above preparation method, in step 3), the molar ratio of the dihydroxy ionic liquid to the aromatic compound is 1:1-3.

[0017] Furthermore, in the above preparation method, in step 3), the aromatic compound is benzene, biphenyl or 1,3,5-triphenylbenzene.

[0018] The above-mentioned dihydroxyl functionalized hyper-crosslinked polyionic liquid is used as a catalyst in catalyzing the synthesis of cyclic carbonates from epoxy compounds.

[0019] Furthermore, the above application is carried out by the following method: mixing a dihydroxy functionalized hyper-crosslinked polyionic liquid catalyst, carbon dioxide and an epoxy compound, and reacting them at a pressure of 0.2 to 1.0 MPa and 90 to 130° C. for 8 to 15 hours.

[0020] Furthermore, in the above application, the added mass of the dihydroxyl functionalized hyper-crosslinked polyionic liquid catalyst is 3%-10% of the mass of the epoxy compound.

[0021] Furthermore, in the above application, the epoxy compound is epichlorohydrin, propylene oxide, 1,2-epoxyethylbenzene, butylene oxide or epibromohydrin.

[0022] The beneficial effects of the present invention are as follows: a dihydroxyl functionalized hyper-crosslinked polyionic liquid is used as a catalyst in the cycloaddition reaction of an epoxy compound and carbon dioxide to synthesize a cyclic carbonate. Compared with a traditional catalyst, the catalytic process of the present invention is simple, the reaction system does not require a solvent and a co-catalyst, the reaction conditions are mild, the catalyst is easy to recycle and reuse multiple times without losing activity, and the yield of the cyclic carbonate is very high. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic structural diagram of the dihydroxyl functionalized hyper-crosslinked polyionic liquid of the present invention.

[0024] Figure 2 This is the H-NMR spectrum of propylene carbonate obtained in Example 3.

[0025] Figure 3 This is the H-NMR spectrum of butylene carbonate obtained in Example 3.

[0026] Figure 4 This is the H NMR spectrum of the styrene oxide ester obtained in Example 3.

[0027] Figure 5 This is the H NMR spectrum of propylene carbonate bromide obtained in Example 3.

[0028] Figure 6 This is the H-NMR spectrum of propylene chlorocarbonate obtained in Example 3. DETAILED DESCRIPTION

[0029] Example 1 Preparation of dihydroxyl functionalized hypercrosslinked polyionic liquid catalyst (I) Preparation of dihydroxyl functionalized hypercrosslinked polyionic liquid (DRB-HY-1)

[0030] Add benzimidazole and tetrabutylammonium bromide to a sodium hydroxide aqueous solution, add 2-bromoethanol and stir at room temperature for 3 hours, then add deionized water to a beaker, extract the mixed solution with chloroform, separate and collect the chloroform layer, and finally dry it with anhydrous Na2SO4, remove the organic solvent with a rotary evaporator, and dry it in a vacuum drying oven to obtain a bromoethanol substitution product; weigh an appropriate amount of the bromoethanol substitution product and 2-bromoethanol in a molar ratio of 1:1.1 and put them into a flask, reflux at 70°C-80°C for 12 hours, wash the obtained solid with anhydrous ethanol 5 times, and obtain a dihydroxy ionic liquid through vacuum drying. The dihydroxy ionic liquid, benzene, anhydrous ferric chloride and dimethoxymethane (molar ratio 1:1:5:5) were added to the dichloroethane solvent in sequence, stirred at room temperature until the mixture was uniform, and then refluxed at 80°C for 24 hours. The solid material obtained after the reaction was washed several times with water, methanol, tetrahydrofuran and chloroform until the filtrate was clear; after vacuum drying, the final product, dihydroxy functionalized hyper-crosslinked polyionic liquid catalyst, was obtained, and the structural formula is as follows:

[0031]

[0032] (II) Preparation of dihydroxyl functionalized hypercrosslinked polyionic liquid (DRB-HY-2)

[0033] The method is the same as (1), except that benzene is replaced by biphenyl (the molar ratio of dihydroxy ionic liquid to biphenyl is 1:3), and a dihydroxy functionalized hyper-crosslinked polyionic liquid (DRB-HY-2) is obtained, and the structural formula is as follows:

[0034]

[0035] (III) Preparation of dihydroxyl functionalized hypercrosslinked polyionic liquid (DRB-HY-3)

[0036] The method is the same as (1), except that benzene is replaced by 1,3,5-triphenylbenzene (the molar ratio of dihydroxy ionic liquid to 1,3,5-triphenylbenzene is 1:3), and a dihydroxy functionalized hyper-crosslinked polyionic liquid (DRB-HY-3) is obtained, and the structural formula is as follows:

[0037]

[0038] Example 2 Cycloaddition reaction of epoxy compounds catalyzed by dihydroxyl functionalized hypercrosslinked polyionic liquid

[0039] (I) Effect of temperature on reaction yield

[0040] In a 50mL autoclave, catalyst DRB-HY-2 and epichlorohydrin were added, mixed, and 0.8MPaCO2 was introduced. The reaction was carried out for 14 hours at the temperature shown in Table 1. The amount of catalyst added was 0.14g, and the amount of epichlorohydrin added was 2.7756g. After the reaction was completed, the yield of cyclic carbonate was calculated, and the results are shown in Table 1.

[0041] Table 1 Yields of cyclic carbonates at different temperatures

[0042] Temperature / ℃ 90 100 110 120 130 Yield / % 56.2 78.9 92.7 95.3 97.2

[0043] (II) Effect of CO2 pressure on reaction yield

[0044] The method is the same as (a), the temperature is 130°C, the pressure is changed as shown in Table 2, and the results are shown in Table 2.

[0045] Table 2 Yields of cyclic carbonates at different CO2 pressures

[0046] Pressure / MPa 0.2 0.4 0.6 0.8 1.0 Yield / % 88.3 93.2 95.6 97.2 97.6

[0047] (III) Effect of catalyst dosage on reaction yield

[0048] The method is the same as (a), the temperature is 130°C, and the amount of catalyst added is changed as shown in Table 3. The results are shown in Table 3.

[0049] Table 3 Yields of cyclic carbonates at different catalyst dosages

[0050] Catalyst dosage / g 0.09 0.11 0.13 0.14 0.15 Yield / % 78.6 85.6 92.7 97.2 97.5

[0051] (IV) Effect of reaction time on reaction yield

[0052] The method was the same as (a), the temperature was 130°C, the reaction time was changed as shown in Table 4, and the results are shown in Table 4.

[0053] Table 4 Yields of cyclic carbonates at different reaction times

[0054] Time / h 8 10 12 14 15 Yield / % 70.5 81.4 91.2 97.2 97.8

[0055] Taking into account factors such as energy consumption, cost, and yield, the dihydroxyl functionalized hypercrosslinked polyionic liquid catalyzes the cycloaddition reaction of epoxy compounds. Preferably, the catalyst and epichlorohydrin are added to a 50mL high-pressure reactor, mixed, and introduced into 0.8MPaCO2. The reaction is carried out at 130°C for 14 hours. The amount of catalyst added is 0.14g, and the amount of epichlorohydrin added is 2.7756g. H NMR spectrum results ( Figure 6 ) is consistent with the reference, proving that the pure target product propylene carbonate was obtained.

[0056] Example 3 Cycloaddition reaction of epoxy compounds catalyzed by dihydroxyl functionalized hypercrosslinked polyionic liquid

[0057] In a 50mL autoclave, different catalysts (as shown in Table 5) and epichlorohydrin were added, mixed, and 0.8MPa CO2 was introduced. The reaction was carried out at 130°C for 14 hours. The amount of catalyst added was 0.14g, and the amount of epichlorohydrin added was 2.7756g. After the reaction was completed, the yield of cyclic carbonate was calculated, and the results are shown in Table 5.

[0058] Table 5 Yields of cyclic carbonates synthesized by different catalysts

[0059] catalyst DRB-HY-1 DRB-HY-2 DRB-HY-3 Yield / % 98.6 99.0 98.5

[0060] In a 50mL autoclave, catalyst DRB-HY-3 and different epoxy compounds (as shown in Table 6) were added, mixed, and 0.8MPa CO2 was introduced. The reaction was carried out at 130°C for 14 hours. The amount of catalyst added was 0.14g, and the amount of epoxy compound added was 2.7756g. After the reaction was completed, the yield of cyclic carbonate was calculated, and the results are shown in Table 6.

[0061] The results of nuclear magnetic hydrogen spectrum detection are shown in Table 6 and Figure 2-Figure 6 shown.

[0062] Table 6 Products synthesized by the reaction of catalyst DRB-HY-3 and different epoxides and their yields

[0063]

[0064]

Claims

1. A dihydroxyl functionalized hypercrosslinked polyionic liquid, characterized in that: The polyionic liquid is composed of dihydroxyl active groups and a hyper-crosslinked structure; the structure of the polyionic liquid is shown in (I): in, 2. The method for preparing a dihydroxyl functionalized hypercrosslinked polyionic liquid according to claim 1, characterized in that: The steps include: 1) benzimidazole and tetrabutylammonium bromide are added to a sodium hydroxide aqueous solution, 2-bromoethanol is added and stirred at room temperature for 3 hours, then deionized water is poured into a beaker, and the mixed solution is extracted with chloroform, the chloroform layer is separated and collected, and finally dried with anhydrous Na2SO4, the organic solvent is removed with a rotary evaporator, and the mixture is dried in a vacuum drying oven to obtain a bromoethanol substitution product; 2) weighing the bromoethanol substitution product and 2-bromoethanol into a flask, refluxing at 70° C.-80° C. for 12 hours, washing the obtained solid with anhydrous ethanol 5 times, and vacuum drying to obtain a dihydroxy ionic liquid; 3) Adding the dihydroxy ionic liquid, the aromatic compound, anhydrous ferric chloride and dimethoxymethane to the dichloroethane solvent, stirring until the mixture is uniform, and then reflux reacting at 80° C. for 24 hours. After the reaction is completed, a solid substance is obtained, and the solid is washed several times with water and methanol, tetrahydrofuran, and chloroform until the filtrate is clear; and drying is performed to obtain the final product, the dihydroxy functionalized hyper-crosslinked polyionic liquid.

3. The preparation method according to claim 2, characterized in that: In step 2), the bromoethanol substitution product and 2-bromoethanol are placed in a flask at a molar ratio of 1:1.

1.

4. The preparation method according to claim 2, characterized in that: In step 3), the molar ratio of the dihydroxy ionic liquid to the aromatic compound is 1:1-3.

5. The preparation method according to claim 2, characterized in that: In step 3), the aromatic compound is benzene, biphenyl or 1,3,5-triphenylbenzene.

6. Use of the dihydroxy functionalized hypercrosslinked polyionic liquid according to claim 1 as a catalyst in catalyzing the synthesis of cyclic carbonates from epoxy compounds.

7. The use according to claim 6, characterized in that: The method is as follows: a dihydroxyl functionalized hyper-crosslinked polyionic liquid catalyst, carbon dioxide and an epoxy compound are mixed, and reacted at a pressure of 0.2-1.0 MPa and 90-130° C. for 8-15 hours.

8. The use according to claim 7, characterized in that: The added mass of the dihydroxyl functionalized hyper-crosslinked polyionic liquid catalyst is 3%-10% of the mass of the epoxy compound.

9. The use according to claim 6, 7 or 8, characterized in that The epoxy compound is epichlorohydrin, propylene oxide, 1,2-epoxyethylbenzene, butylene oxide or epibromohydrin.

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