Functionalized double-acid supported ionic liquid as well as preparation method and application thereof

Abstract

The invention relates to the technical field of ionic liquid synthesis and catalytic synthesis of hydroxybutyl acrylate, in particular to a functional double-acid supported ionic liquid as well as a preparation method and application thereof. The functional double-acid supported ionic liquid comprises an MOFs (Metal-Organic Frameworks) material UiO-66-SO3H and a double-acid ionic liquid supported on the MOFs material. The synthesis of the double-acidified ionic liquid comprises the following steps: synthesizing a dimethyl monomer by adopting imidazole, pyrrolidine or morpholine; reacting the dimethyl monomer with 1, 4-butane sultone to generate sulfonic acid inner salt; and acidifying sulfonic acid internal hydrochloric acid. The functionalized double-acid supported ionic liquid has the advantages that the heat stability and the reusability are good; the product is immiscible with an organic reaction solvent and is easier to separate and recover; as a catalyst for catalyzing esterification reaction, the catalytic activity is obviously improved; as a solid catalyst in an esterification reaction, the catalyst can be applied to a fixed bed reactor, continuous esterification is realized, and the productivity is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of ionic liquid synthesis and catalytic synthesis of hydroxybutyl acrylate, and in particular to a functionalized bis-acidic supported ionic liquid and a preparation method and application thereof. Background Art

[0002] Among catalysts, ionic liquids (ILs) and metal-organic frameworks (MOFs) have garnered widespread attention as novel catalysts. Ionic liquids are molten salts composed of anions and cations. These ions can be designed or tuned to produce high-performance catalysts. However, ILs as catalysts often form homogeneous systems with reactants or products, making their reuse difficult. Immobilizing ILs on supports to form a solid-liquid two-phase system with reactants and products is considered an ideal approach for ionic liquid catalysis.

[0003] Common supports, such as silicon-based materials, carbon-based materials, and polymers, are primarily non-porous or sparingly porous. The active components of ionic liquids cannot be evenly distributed on their surfaces or within their pores. Furthermore, the ionic liquid loading capacity of common supports is limited, which directly affects the catalytic activity of the ionic liquid.

[0004] MOFs, as emerging porous materials with framework structures, have attracted increasing attention as catalysts or catalyst supports in a wide range of reactions due to their unsaturated metal sites (Lewis acid), large surface area, structural tunability, and other properties. However, MOFs themselves generally exhibit low catalytic activity. Given that MOFs are crystalline porous materials composed of metal clusters and organic ligands, their self-assembled structure allows for the manipulation of pore size, shape, and even the groups on the ligands. Therefore, combining MOFs with ionic liquids as a platform is an ideal approach for preparing composite catalysts.

[0005] To date, several attempts have been reported to prepare IL@MOFs catalysts using ILs as active sites and MOFs as supports. However, these ionic liquid immobilization methods primarily rely on physical adsorption, and the resulting ionic liquid composites are extremely unstable in polar solvents. Furthermore, the MOF channels are easily blocked by the ionic liquids. Therefore, designing and obtaining stable IL@MOFs composites while maintaining their porous structure remains a challenge.

[0006] Recently, post-synthetic ligand exchange (PSLE) has become a popular method for introducing functionalized ligands that are difficult to form regular framework materials through coordination self-assembly. The main effect of PSLE ​​is that the initial ligands in MOF microcrystals can be easily replaced by highly functionalized ligands. The mechanism of PSLE ​​is that due to the reversibility of coordination bonds, MOFs can partially dissociate into small amounts of metal ions and ligands in polar solutions. When high concentrations of similar coordination compounds are added, the coordination equilibrium is disrupted. At high concentrations, similar coordination compounds will coordinate to the metal sites and lead to new decomposition of MOF microcrystals. When PSLE ​​occurs between a bissulfonic acid-functionalized ionic liquid and MOFs, we obtain a method for synthesizing a composite catalyst with a bissulfonic acid ionic liquid as the active site and MOFs as the support.

[0007] Bissulfonic acid-functionalized ionic liquids (IILs) can be dissolved in water as molten salts in the form of cations and anions. The cations of IILs have similar coordination properties to the 2-sulfonated terephthalic acid (H2PTSA) ligand in UiO-66-SO3H (a type of MOFs material). In addition, the anions of IILs can be replaced with other anions to adjust the catalytic activity. Therefore, IILs are considered to be ideal coordination compounds. Here, the prepared 1,1'-(methane)bis(3-sulfonated butylimidazole) ion {[Bis-BsImM] +} as a cation to replace the H2PTSA ligand of UiO-66-SO3H. UiO-66-SO3H is a typical zirconium-based metal oxide semiconductor with good chemical and thermal stability. In addition, the prepared composite catalyst can also be used for esterification reaction, so [PTSA] - It is considered to be a suitable anion for disulfonic acid functionalized ionic liquids. [Bis-BsImM][PTSA]2@UiO-66-SO3H not only retains the advantages of acidic ionic liquids as catalysts, but also has a rich pore structure and a large specific surface area, which can increase the reaction contact area. In polar solvents, some H2STPA can be [Bis-BsImM] + The catalyst [Bis-BsImM][PTSA]2@UiO-66-SO3H was prepared by further anion replacement and applied as a heterogeneous catalyst to the esterification of acrylic acid and 1,4-butanediol in a mixed phase system. In this reaction system, [Bis-BsImM][PTSA]2@UiO-66-SO3H exhibited high catalytic activity. Summary of the Invention

[0008] In order to solve the problem in the prior art that it is difficult to obtain a stable IL@MOFs composite material and maintain its porous structure, the present invention provides a functionalized bis-acidic supported ionic liquid and a preparation method thereof, and uses it to catalyze the synthesis of 4-hydroxybutyl acrylate, which not only improves its yield and selectivity but also enables multiple utilization of the catalyst.

[0009] To achieve the above-mentioned object of the invention, the present invention provides a functionalized bis-acidic supported ionic liquid, comprising a MOFs material UiO-66-SO3H and a bis-acidified ionic liquid supported on the MOFs material, wherein the structural formula of the bis-acidified ionic liquid is as shown in Formula I, Formula II or Formula III:

[0010] Formula I

[0011] Formula II

[0012] Formula III; Among them, A — Cl — , HSO4 — , CF3SO3 — , CF3CH3COO — ,4-(CH3)PhSO3 — or H2PO4 — Any one of .

[0013] Preferably, the molar ratio of the double-acidified ionic liquid to UiO-66-SO3H is (1-20):1.

[0014] The present invention also provides a method for preparing the above-mentioned functionalized bis-acidic loaded ionic liquid, comprising the following steps: (1) synthesis of bissulfonic acid functionalized ions: 1) Using imidazole, pyrrolidine or morpholine to synthesize a dimethyl monomer; the structural formula of the dimethyl monomer is shown in Formula IV-VI:

[0015] Formula IV

[0016] Formula V

[0017] Formula VI 2) reacting the dimethyl monomer described in step 1) with 1,4-butane sultone to form a sultate; the structural formula of the sultate is shown in Formula VII to Formula IX:

[0018] Formula VII

[0019] Formula VIII

[0020] Formula IX 3) Acidifying the sulfonic acid inner hydrochloride described in step 2) to obtain a double-acidified ionic liquid, wherein the structural formula of the double-acidified ionic liquid is as shown in Formula I to Formula III; (2) Synthesis of metal organic framework MOFs material UIO-66-SO3H; (3) Synthesis of sulfonic acid functionalized bis-acidic supported ionic liquid: The bis-sulfonic acid functionalized ionic liquid was loaded on UIO-66-SO3H, and the steps were as follows: The prepared dianidinic ionic liquid is dissolved in deionized water, and then UiO-66-SO3H is dispersed in the aqueous solution of the dianidinic ionic liquid, followed by ultrasonic treatment to enhance the diffusibility of the dianidinic ionic liquid into the micropores of the UiO-66-SO3H. The obtained homogeneous solution is poured into a reactor, heated at 100-120°C for reaction, and naturally cooled to room temperature after the reaction is completed. The functionalized dianidinic supported ionic liquid is obtained by centrifugation, washing, and drying.

[0021] Preferably, in step 3) of step (1), any one of concentrated hydrochloric acid, concentrated sulfuric acid, trifluoromethanesulfonic acid, trifluoroacetic acid, p-toluenesulfonic acid, and phosphoric acid is used for acidification.

[0022] Further preferably, the chemical formula of the dimethyl monomer in step (1) is as shown in Formula IV, the dioxygenated ionic liquid is [Bis-BsImM][PTSA]2, and the preparation method of [Bis-BsImM][PTSA]2 comprises the following steps: S1. Imidazole and dichloromethane are mixed in a 1:1 molar ratio, and KOH and tetra-n-butylammonium bromide (TBAB) are added to obtain a reaction mixture. The mixture is reacted at room temperature for 6-24 hours. The reaction mixture is extracted with ethanol and separated by column chromatography to obtain bisimidazole methane. The molar amount of KOH is twice that of imidazole, and the mass of tetra-n-butylammonium bromide is 3 wt % of the mass of the reaction mixture. S2. Bisimidazole methane and 1,4-butane sultone were mixed in anhydrous acetonitrile at a molar ratio of 1:2 and reacted at 80°C for 24 hours to obtain a white solid. The solid was ground, washed with ethanol, and dried under vacuum to obtain the bisimidazole sulfonic acid salt. S3. The white solid was ground into powder and mixed with p-toluenesulfonic acid in a molar ratio of 1:2 in anhydrous toluene. The mixture was heated at 80°C for 24 h. The mixture was then washed with acetonitrile and diethyl ether and dried under vacuum to obtain the final ionic liquid [Bis-BsImM][PTSA]2 as a yellow viscous liquid.

[0023] Further preferably, the chemical formula of the dimethyl monomer in step (1) is as shown in VI, the dioxygenated ionic liquid is [Bis-BsMOR][HSO4]2, and the preparation method of [Bis-BsMOR][HSO4]2 comprises the following steps: 1) Synthesis of bismorpholine methane Morpholine, potassium hydroxide, tetra-n-butylammonium bromide, and dichloromethane were mixed evenly and reacted at room temperature for 18 hours. Then, 200 ml of ethanol was added to the reaction solution for extraction. The extract was separated by column chromatography with petroleum ether:ethyl acetate = 18:1 to obtain white solid bismorpholine methane; The molar ratio of morpholine to dichloromethane is 1:1; the molar amount of KOH is twice that of imidazole, and the mass of tetra-n-butylammonium bromide is 3wt% of the mass of the reaction mixture; 2) Synthesis of bismorpholine sulfonic acid inner salt Bismorpholine methane, 1,4-butane sultone, and anhydrous acetonitrile were mixed uniformly, heated to 80°C, and reacted for 18 hours. The obtained white solid was crushed into powder, washed with ethanol, and vacuum-dried to obtain a white solid bismorpholine sulfonic acid salt; the molar ratio of the bismorpholine methane to 1,4-butane sultone was 1:2.6; 3) Synthesis of 1,1'-(methane)bis(3-sulfonic acid butylmorpholine) p-toluenesulfonic acid ionic liquid After mixing bismorpholine sulfonic acid inner salt and concentrated sulfuric acid, the temperature was raised to 85°C, reacted for 18 hours, cooled to room temperature, rotary evaporated, and vacuum dried to obtain the ionic liquid [Bis-BsMOR][HSO4]2; the dosage ratio of the bismorpholine sulfonic acid inner salt and concentrated sulfuric acid was 0.87:1 g / mL.

[0024] Preferably, the preparation method of the MOFs material UiO-66-SO3H in step (2) comprises the following steps: Zirconium nitrate hexahydrate and 2-sulfonatoterephthalic acid (PTSA) in a molar ratio of 1:1 and a small amount of acetic acid are dissolved in a large amount of anhydrous N,N-dimethylformamide (DMF) to form a mixed solution. The mixed solution is transferred to an oil bath and continuously heated to 100-120°C for reaction for 24-48 hours. After cooling to room temperature, the obtained reaction product is filtered and washed three times with DMF and methanol, respectively, and then filtered again to obtain a white solid UiO-66-SO3H.

[0025] Preferably, the ultrasonic treatment time in step (3) is 30-60 minutes.

[0026] Preferably, the heating reaction time in step (3) is 36-72 hours.

[0027] Preferably, the washing in step (3) is washing three times with DMF and ethanol respectively, and the drying is vacuum drying.

[0028] The present invention also provides application of the functionalized diacidic supported ionic liquid in catalytic synthesis of 4-hydroxybutyl acrylate (HBA).

[0029] Preferably, the method for synthesizing 4-hydroxybutyl acrylate catalyzed by a functionalized bis-acidic supported ionic liquid comprises the following steps: Acrylic acid and 1,4-butanediol are uniformly mixed, a diacidic supported ionic liquid catalyst and a polymerization inhibitor are added, and the reaction is carried out at 80-130°C.

[0030] Preferably, the molar ratio of acrylic acid to 1,4-butanediol is 1:(1-3).

[0031] Preferably, the added amount of the bis-acidic supported ionic liquid is 1-20 wt % of the acrylic acid.

[0032] Preferably, the amount of the polymerization inhibitor added is 1-5 wt % of the acrylic acid.

[0033] Preferably, the polymerization inhibitor is hydroquinone and / or p-hydroxyanisole.

[0034] Preferably, the reaction time is 2-25 hours.

[0035] Compared with the prior art, the technical solution of the present invention has the following beneficial effects: (1) The present invention utilizes the monomer in [Bis-BsImM][PTSA]2 to exchange with the ligand 2-sulfonatoterephthalic acid (PTSA) in UiO-66-SO3H for loading. The obtained [Bis-BsImM][PTSA]2@UiO-66-SO3H has good thermal stability and reusability, and has great potential as a catalyst in esterification reactions.

[0036] (2) The diacidic supported ionic liquid of the present invention is immiscible with the organic reaction solvent. Compared with a single liquid acid catalyst, the ionic liquid and the generated 4-hydroxybutyl acrylate (HBA) are easier to separate and recover.

[0037] (3) In the present invention, the ionic liquid [Bis-BsImM][PTSA]2 is coordinated and loaded with UiO-66-SO3H to perform esterification, and the catalytic activity is significantly improved. This is because the reaction raw materials are adsorbed into the gaps containing a large number of catalytic active sites, resulting in higher catalytic activity and thus accelerating the esterification reaction.

[0038] (4) The diacidic supported ionic liquid in the present invention contains two -SO3H groups and two 4-(CH3)PhSO3 anions, and has higher catalytic esterification activity than single SO3 and 4-(CH3)PhSO3 anions.

[0039] (5) The bis-acidic supported ionic liquid in the present invention can be used as a solid catalyst in the esterification reaction in a fixed bed reactor to achieve continuous esterification and increase production capacity. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 This is the H NMR spectrum of the functionalized bis-acidic supported ionic liquid described in Example 1 1 H NMR; Figure 2 This is the chromatographic analysis spectrum of the product system of Application Example 1; Figure 3 It is the chromatographic analysis spectrum of the product system of Comparative Example 1. DETAILED DESCRIPTION

[0041] The technical solution of the present invention is described in detail below through specific implementation methods in combination with examples. It should be noted that the innovative advantages and technical features of the present invention can be made more explicit through systematic illustrations. It should be noted that the embodiments provided are only exemplary demonstrations of the technical principles and do not constitute a limitation on the scope of the claims of the present invention. Those skilled in the relevant fields should understand that, under the premise of strictly adhering to the core design concept of the present invention and the boundaries of the claims, the specific implementation details and forms of expression of the technical solution can be adaptively adjusted or equivalently replaced, and such technical variations all fall within the scope of protection claimed by the patent of the present invention.

[0042] Unless otherwise specified, the experimental methods involved in this document refer to the general experimental procedures in this field; the reagents and materials involved, unless otherwise specified, refer to conventional chemical preparations that can be obtained through standardized commercial channels; the experimental devices and instruments described are all conventional experimental instruments that meet industry standards.

[0043] Example 1 A method for preparing a functionalized bis-acidic supported ionic liquid comprises the following steps: (1) Synthesis of disulfonic acid functionalized ions 1) Synthesis of bisimidazolyl methane Weigh 34.04 g of imidazole, 56.11 g of potassium hydroxide, 3.98 g of tetra-n-butylammonium bromide, and 42.465 g of dichloromethane and add them separately to a 500 ml reaction flask. React at room temperature for 24 h. After the reaction, add 200 ml of ethanol to the reaction solution for extraction. The extract is separated by column chromatography with petroleum ether: ethyl acetate = 20:1 to obtain 17.04 g of white solid bisimidazolyl methane with a purity greater than 98% and a yield of 46%.

[0044] 2) Synthesis of Bisimidazole Sulfonic Acid Indole Weigh 17.04 g of bisimidazolyl methane, 38.13 g of 1,4-butane sultone, and 50 ml of anhydrous acetonitrile and put them into a 250 ml reaction flask respectively. Heat to 80 ° C and react for 24 h to obtain 43.44 g of white solid. After crushing into powder, wash with 40 ml of ethanol and dry in a vacuum drying oven to obtain 41.10 g of white solid bisimidazolyl sulfonic acid salt with a purity of 98% and a yield of 85%.

[0045] 3) Synthesis of 1,1'-(methane)bis(3-sulfonic acid butylimidazole) p-toluenesulfonic acid ionic liquid Weigh 41.10 g of bisimidazolyl sulfonic acid inner salt, 31.5 ml of p-toluenesulfonic acid, and 80 ml of anhydrous toluene into a 250 ml reactor. Heat to 80°C and react for 24 hours. Wash once with 80 ml of acetonitrile and once with 80 ml of diethyl ether, then dry in a vacuum oven to obtain 60.57 g of the ionic liquid [Bis-BsImM][PTSA]2, a yellow, viscous liquid with a purity of 98% and a yield of 81%.

[0046] (2) Synthesis of UiO-66-SO3H 78.64 g of zirconium (IV) nitrate hexahydrate, 49.24 g of 2-sulfonatoterephthalic acid (PTSA), and 30 ml of acetic acid were dissolved in 200 ml of anhydrous N, N-dimethylformamide (DMF) to form a mixed solution. The mixed solution was transferred to an oil bath and continuously heated to 120 °C for 24 h. After cooling to room temperature, the obtained reaction product was filtered and then washed three times with 150 mL of N, N-dimethylformamide and 150 ml of methanol, respectively. (3) Synthesis of [Bis-BsImM][PTSA]2@UiO-66-SO3H The prepared ligand [Bis-BsImM][PTSA]2 (0.01 mol) was dissolved in 20 mL of deionized water. Then, 4 g of UiO-66-SO3H was dispersed in the [Bis-BsImM][PTSA]2 solution. The mixed solution was sonicated for 30 minutes. The resulting solution was poured into a 100 mL reactor and heated at 120°C for 72 hours. After cooling to room temperature, the solid was collected by centrifugation and washed three times with 20 mL of DMF and 20 mL of ethanol, respectively. After vacuum drying, 7.5 g of the bis-acidic supported ionic liquid [Bis-BsImM][PTSA]2@UiO-66-SO3H was obtained, with a yield of 64%.

[0047] Example 2 A method for preparing a functionalized bis-acidic supported ionic liquid comprises the following steps: (1) Synthesis of disulfonic acid functionalized ions 1) Synthesis of bismorpholine methane Weigh 65.34 g of morpholine, 84.165 g of potassium hydroxide, 6.40 g of tetra-n-butylammonium bromide, and 63.70 g of dichloromethane and add them separately to a 500 ml reaction flask. React at room temperature for 18 h. After the reaction, add 200 ml of ethanol to the reaction solution for extraction. The extract is separated by column chromatography with petroleum ether: ethyl acetate = 18:1 to obtain 30.03 g of white solid bismorpholine methane with a purity greater than 98% and a yield of 43%.

[0048] 2) Synthesis of bismorpholine sulfonic acid inner salt Weigh 30.03 g of bismorpholine methane, 57.20 g of 1,4-butane sultone, and 100 ml of anhydrous acetonitrile and put them into a 250 ml reaction flask respectively. Heat the temperature to 80 ° C and react for 18 h to obtain 62.62 g of a white solid. After grinding into powder, wash with 80 ml of ethanol and dry in a vacuum drying oven to obtain 60.64 g of a white solid bismorpholine sulfonic acid inner salt with a purity of 97.8% and a yield of 82%.

[0049] 3) Synthesis of 1,1'-(methane)bis(3-sulfonic acid butylmorpholine) p-toluenesulfonic acid ionic liquid Weigh 60.64g of bismorpholinesulfonic acid inner salt and 70ml of concentrated sulfuric acid into a 250ml reactor. Heat to 85°C, react for 18 hours, then cool to room temperature. Rotary evaporation and vacuum drying yielded 70.13g of the ionic liquid [Bis-BsMOR][HSO4]2, a yellow, viscous liquid with a purity of 98% and a yield of 81%.

[0050] (2) Synthesis of UiO-66-SO3H 117.96 g of zirconium (IV) nitrate hexahydrate, 73.86 g of 2-sulfonatoterephthalic acid (PTSA), and 50 ml of acetic acid were dissolved in 400 ml of anhydrous N, N-dimethylformamide (DMF) to form a mixed solution. The mixed solution was transferred to an oil bath and heated to 130 °C for 18 h. After cooling to room temperature, the obtained reaction product was filtered and washed three times with 250 mL of N, N-dimethylformamide and 250 ml of methanol, respectively. (3) Synthesis of [Bis-BsMOR][PTSA]2@UiO-66-SO3H The prepared ligand [Bis-BsMOR][PTSA]2 (0.01 mol) was dissolved in 20 mL of deionized water. 5 g of UiO-66-SO3H was then dispersed in the [Bis-BsMOR][PTSA]2 solution. The mixed solution was sonicated for 30 minutes, poured into a 125 mL reactor, and heated at 130°C for 60 hours. After cooling to room temperature, the solid was collected by centrifugation and washed three times with 30 mL of DMF and 30 mL of ethanol, respectively. After vacuum drying, 6.2 g of the bis-acidic supported ionic liquid [Bis-BsMOR][PTSA]2@UiO-66-SO3H was obtained.

[0051] Application Example 1 The bis-acidic supported ionic liquid [Bis-BsImM][PTSA]2@UiO-66-SO3H obtained in Example 1 was used to catalyze the synthesis of 4-hydroxybutyl acrylate.

[0052] 28.521 g of acrylic acid, 54.136 g of 1,4-butanediol, 0.5 g of bis-acidic supported ionic liquid, and 0.29 g of hydroquinone were added to the reactor respectively, and the temperature was raised to 80°C. The reaction was carried out for 8-10 hours. The product system was subjected to chromatographic analysis. The peak table is shown in Table 1, and the chromatogram is shown in Figure 2 As shown, the results showed that the conversion rate of 1,4-butanediol was 80.5%, the yield of 4-hydroxybutyl acrylate was 94%, and the selectivity was 95%. Table 1. Peak list of the reaction solution chromatographic analysis in Application Example 1

[0053] Comparative Example 1 Synthesis of 4-hydroxybutyl acrylate using p-toluenesulfonic acid as a catalyst The same reaction conditions and feed as in the application example were used, and the catalyst was changed to p-toluenesulfonic acid. The conversion rate, yield and selectivity were shown in Table 3. The product system was subjected to chromatographic analysis. The peak table was shown in Table 2, and the chromatogram was shown in Table 2. Figure 3 shown.

[0054] Table 2. Peak table of the reaction solution chromatographic analysis in Comparative Example 1

[0055] Comparative Example 2 Synthesis of 4-hydroxybutyl acrylate using methanesulfonic acid as a catalyst The same reaction conditions and feed as in the application example were used, but the catalyst was changed to methanesulfonic acid. The results are shown in Table 3.

[0056] Comparative Example 3 Synthesis of 4-hydroxybutyl acrylate using concentrated sulfuric acid as an acidic catalyst The same reaction conditions and feed as in the application example were used, but the catalyst was changed to concentrated sulfuric acid. The results are shown in Table 3. Table 3 Comparison of esterification reaction data

[0057] The yield of 4-hydroxybutyl acrylate (HBA) obtained in the application example is compared with the results of comparative examples 1, 2, and 3 and is listed in Table 1. It can be seen that the conversion rate of [Bis-BsImM][PTSA]2@UiO-66-SO3H for 1,4-butanediol is higher than that of most similar acidic liquid catalysts such as p-toluenesulfonic acid, methanesulfonic acid, and concentrated sulfuric acid. [Bis-BsImM][PTSA]2@UiO-66-SO3H has larger pores and higher specific surface area. Its excellent catalytic performance can be attributed to the synergistic effect between surface adsorption and protonation catalysis. Compared with p-toluenesulfonic acid, methanesulfonic acid, and concentrated sulfuric acid anions, the bis-acidic supported ionic liquid containing two acid anions has better catalytic activity.

[0058] Application Example 2 The bis-acidic supported ionic liquid [Bis-BsImM][PTSA]2@ After repeated use of UiO-66-SO3H for the synthesis of 4-hydroxybutyl acrylate, the conversion of 1,4-butanediol was 78.1%, the yield of 4-hydroxybutyl acrylate was 92.5%, and the selectivity was 90.4%. After repeated use twice, the conversion of 1,4-butanediol was 77.8%, the yield of 4-hydroxybutyl acrylate was 92%, and the selectivity was 90%. After repeated use three times, the conversion of 1,4-butanediol was 76.5%, the yield of 4-hydroxybutyl acrylate was 91.5%, and the selectivity was 89.5%. After repeated use four times, the conversion of 1,4-butanediol was 76.2%, the yield of 4-hydroxybutyl acrylate was 91.3%, and the selectivity was 89.2%. After repeated use five times, the conversion of 1,4-butanediol was 75.6%, the yield of 4-hydroxybutyl acrylate was 91%, and the selectivity was 89%. Overall, the catalyst still has strong catalytic activity after repeated use and can effectively catalyze the synthesis of 4-hydroxybutyl acrylate.

Claims

1. A functionalized bis-acidic supported ionic liquid, characterized in that: It includes a MOFs material UiO-66-SO3H and a double-acidified ionic liquid supported on the MOFs material, wherein the structural formula of the double-acidified ionic liquid is as shown in Formula I, Formula II or Formula III: Formula I Formula II Formula III; Among them, A — Cl — , HSO4 — , CF3SO3 — , CF3CH3COO — ,4-(CH3)PhSO3 — or H2PO4 — Any one of .

2. The method for preparing a functionalized bis-acidic supported ionic liquid according to claim 1, wherein: The molar ratio of the double-acidified ionic liquid to UiO-66-SO3H is (1-20):

1.

3. The method for preparing a functionalized bis-acidic supported ionic liquid according to claim 1, wherein: The following steps are involved: (1) Synthesis of disulfonic acid functionalized ions; (2) Synthesis of metal organic framework MOFs material UIO-66-SO3H; (3) Synthesis of sulfonic acid functionalized diacidic supported ionic liquids; The step (1) comprises the following steps: 1) Using imidazole, pyrrolidine or morpholine to synthesize a dimethyl monomer; the structural formula of the dimethyl monomer is shown in Formula IV-VI: Formula IV Formula V Formula VI 2) reacting the dimethyl monomer described in step 1) with 1,4-butane sultone to form a sultate; the structural formula of the sultate is shown in Formula VII to Formula IX: Formula VII Formula VIII Formula IX 3) Acidifying the sulfonic acid inner hydrochloride described in step 2) to obtain a double-acidified ionic liquid, wherein the structural formula of the double-acidified ionic liquid is as shown in Formula I to Formula III; The step (3) includes the following steps: The bissulfonic acid functionalized ionic liquid is loaded on UIO-66-SO3H in the following steps: The prepared bis-acidified ionic liquid is dissolved in deionized water, and then UiO-66-SO3H is dispersed in the aqueous solution of the bis-acidified ionic liquid, followed by ultrasonic treatment. The obtained homogeneous solution is poured into a reactor, heated at 100-120°C for reaction, and naturally cooled to room temperature after the reaction is completed. The functionalized bis-acidic supported ionic liquid is obtained by centrifugation, washing, and drying.

4. The method for preparing a functionalized bis-acidic supported ionic liquid according to claim 3, wherein: In step 3) of step (1), any one of concentrated hydrochloric acid, concentrated sulfuric acid, trifluoromethanesulfonic acid, trifluoroacetic acid, p-toluenesulfonic acid, and phosphoric acid is used for acidification.

5. The method for preparing a functionalized bis-acidic supported ionic liquid according to claim 4, characterized in that: The chemical formula of the dimethyl monomer in step (1) is shown in Formula IV, the di-acidified ionic liquid is [Bis-BsImM][PTSA]2, and the preparation method of [Bis-BsImM][PTSA]2 comprises the following steps: S1. Imidazole and dichloromethane were mixed in a molar ratio of 1:1, KOH and tetra-n-butylammonium bromide were added to obtain a reaction mixture, and the reaction was carried out at room temperature for 6-24 hours. The reaction solution was extracted with ethanol and separated by column chromatography to obtain bisimidazole methane; the molar amount of KOH was twice the molar amount of imidazole, and the mass of the tetra-n-butylammonium bromide was 3wt% of the mass of the reaction mixture; S2. Bisimidazole methane and 1,4-butane sultone were mixed in anhydrous acetonitrile at a molar ratio of 1:2 and reacted at 80°C for 24 hours to obtain a white solid. The solid was ground, washed with ethanol, and dried under vacuum to obtain the bisimidazole sulfonic acid salt. S3. Mix bisimidazolesulfonic acid inner salt and p-toluenesulfonic acid in a molar ratio of 1:2 in anhydrous toluene, heat at 80°C for 24 hours, wash with acetonitrile and diethyl ether, and vacuum dry to obtain the final ionic liquid [Bis-BsImM][PTSA]2 as a yellow viscous liquid.

6. The method for preparing a functionalized bis-acidic supported ionic liquid according to claim 3, characterized in that: The preparation method of the MOFs material UiO-66-SO3H in step (2) comprises the following steps: Zirconium nitrate hexahydrate and 2-sulfonatoterephthalic acid are dissolved in anhydrous N,N-dimethylformamide in a molar ratio of 1:1 with acetic acid to form a mixed solution; the mixed solution is transferred to an oil bath, continuously heated to 100-120° C. and reacted for 24-48 hours. After cooling to room temperature, the obtained reaction product is filtered, and then washed with DMF and methanol three times respectively, and then filtered to obtain a white solid UiO-66-SO3H; preferably, the mass of the acetic acid is 0.1-0.3 times the total mass of the zirconium nitrate hexahydrate and the 2-sulfonatoterephthalic acid; the mass of the DMF is 1-5 times the total mass of the zirconium nitrate hexahydrate and the 2-sulfonatoterephthalic acid.

7. The method for preparing a functionalized bis-acidic supported ionic liquid according to claim 3, characterized in that: In step (3), the molar ratio of the double-acidified ionic liquid to UiO-66-SO3H is (1-20):1; Preferably, the ultrasonic treatment time in step (3) is 30-60 minutes; Preferably, the heating reaction time in step (3) is 36-72 hours; Preferably, the washing in step (3) is washing three times with DMF and ethanol respectively, and the drying is vacuum drying.

8. Use of the functionalized bis-acidic supported ionic liquid according to claim 1 or 2 or the functionalized bis-acidic supported ionic liquid prepared by the preparation method according to any one of claims 3 to 7 in the catalytic synthesis of 4-hydroxybutyl acrylate.

9. Use of the functionalized diacidic supported ionic liquid according to claim 8 in the catalytic synthesis of 4-hydroxybutyl acrylate, characterized in that: The method for synthesizing 4-hydroxybutyl acrylate by catalysis of a functionalized bis-acidic supported ionic liquid comprises the following steps: Mix acrylic acid and 1,4-butanediol evenly, add a diacidic supported ionic liquid catalyst and a polymerization inhibitor, and react at 80-130°C; Preferably, the molar ratio of acrylic acid to 1,4-butanediol is 1:(1-3); Preferably, the amount of the bis-acidic supported ionic liquid added is 1-20 wt % of the acrylic acid; Preferably, the amount of the polymerization inhibitor added is 1-5 wt % of the acrylic acid.

10. Use of the functionalized diacidic supported ionic liquid according to claim 9 in catalytic synthesis of 4-hydroxybutyl acrylate, characterized in that: The polymerization inhibitor is hydroquinone and / or p-hydroxyanisole; preferably, the reaction time is 2-25 hours.

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