Activating catalyst for synthesizing methyl p-tert-butylformate and preparation method of activating catalyst

Abstract

The invention discloses an activating catalyst for synthesizing methyl p-tert-butylformate and a preparation method thereof, belongs to the technical field of catalyst preparation, and aims to solve the problem of low catalytic efficiency of a resin catalyst in an esterification process when the methyl p-tert-butylformate is synthesized in the prior art. The technical problems that an ionic liquid catalyst is not easy to separate, is difficult to recycle and is not suitable for continuous industrial production are solved. The invention provides a preparation method of an activating catalyst for synthesizing methyl p-tert-butylformate, which comprises the following steps: S1, mixing a strongly acidic solid catalyst and a modified molecular sieve, and carrying out ball milling to obtain a mixture; and S2, adding the mixture into an ionic liquid containing magnesium and aluminum metal elements for activation, and synthesizing the activated catalyst for methyl p-tert-butylformate. The activated catalyst prepared by the invention has the advantages of corrosion resistance, high catalytic efficiency and repeated recycling.

Description

Technical Field

[0001] The present invention relates to the technical field of catalyst preparation, and particularly relates to an activated catalyst for synthesizing methyl p-tert-butylbenzoate and a preparation method thereof. Background Art

[0002] Methyl p-tert-butylbenzoate is an important pharmaceutical and chemical intermediate and an organic synthesis intermediate, which is widely used in the production of chemical synthesis, pharmaceuticals, cosmetics, and fragrances, and has a large market demand. In large-scale industrial production, p-tert-butylbenzoic acid and anhydrous methanol are usually used as raw materials, and under the action of a catalyst, methyl p-tert-butylbenzoate is generated through an esterification reaction. In the above esterification process, commonly used catalysts include resin-based solid catalysts, ionic liquid catalysts, etc.; the catalytic efficiency of ionic liquid catalysts is higher, but they are not easy to separate and are not suitable for the disadvantages of continuous industrial production.

[0003] Patent application CN107311868A discloses a method for preparing methyl p-tert-butylbenzoate. The above esterification process uses sulfonic acid resin as an esterification catalyst; the sulfonic acid resin catalyst has the advantages of no equipment corrosion, easy separation of products, and recyclability of the catalyst, and is suitable for large-scale industrial production. However, the resin catalyst has the disadvantages of weak self-acidity and low catalytic efficiency.

[0004] In view of the technical defects in this regard, a solution is now proposed. Summary of the Invention

[0005] The purpose of the present invention is to provide an activated catalyst for synthesizing methyl p-tert-butylbenzoate and a preparation method thereof, which are used to solve the problem of low catalytic efficiency when using resin as an esterification catalyst in the esterification process for synthesizing methyl p-tert-butylbenzoate in the prior art; when using an ionic liquid catalyst, there are technical problems such as not being easy to separate, difficult to recycle, and not being suitable for continuous industrial production.

[0006] The purpose of the present invention can be achieved through the following technical solutions: A preparation method of an activated catalyst for synthesizing methyl p-tert-butylbenzoate includes the following steps: S1. A strongly acidic solid catalyst and a modified molecular sieve are mixed and ball-milled to obtain a mixture. S2. The mixture is added to a metal ionic liquid for activation, and then filtered to obtain a solid; the solid is cold-pressed to obtain a pre-pressed block; the pre-pressed block is dried and then naturally cooled to obtain an activated catalyst for synthesizing methyl p-tert-butylbenzoate.

[0007] The catalyst synthesized by the present invention is an impregnated catalyst, that is, after mixing two parts of a strongly acidic solid catalyst and a modified molecular sieve, it is impregnated in a metal ionic liquid to synthesize an impregnated catalyst.

[0008] Furthermore, in step S1, the preparation method of the strongly acidic solid catalyst includes the following steps: A1. Gelatin is completely dissolved in deionized water to obtain a mixed solution; then, a NaOH solution is added dropwise to adjust the pH value of the mixed solution to 7 to obtain an aqueous phase; divinylbenzene, glycerol trimethacrylate, and an initiator are mixed evenly to obtain an oil-phase mixture; the oil-phase mixture is added to the aqueous phase to obtain a reaction system; the reaction system is heated to 75 - 80 °C and reacted at this temperature for 2 - 3 h to obtain a prepolymer; Using gelatin as a dispersant, gelatin is dissolved in water to obtain an aqueous phase; under the action of an initiator, divinylbenzene monomers and glycerol trimethacrylate undergo free radical addition polymerization to form a prepolymer, which is the skeleton of the prepared strongly acidic solid catalyst.

[0009] A2. Glycidyl methacrylate is added to the prepolymer, and then the temperature is raised to 90 - 95 °C and kept at this temperature for 2 - 4 h for reaction, and then the reaction is stopped and cooled to room temperature. After post-treatment, polymer spheres are obtained; Under the continued action of the initiator, the prepolymer continues to react with the unsaturated double bonds in glycidyl methacrylate to obtain polymer spheres grafted with glycidyl methacrylate.

[0010] The polymerization reaction of divinylbenzene monomers and glycerol trimethacrylate is followed by crosslinking with glycidyl methacrylate. The reaction formula for preparing polymer spheres is as follows:

[0011] A3. Sodium sulfamate is first dissolved in water, and then aluminum chloride is added and mixed evenly to obtain a mixture; the mixture is heated to 80 - 100 °C, and a NaOH solution is added dropwise to adjust the pH value of the mixture to 8 - 10; then, polymer spheres are added and kept at 80 - 100 °C for 15 - 20 h for reaction. After post-treatment, the strongly acidic solid catalyst is prepared.

[0012] The epoxy groups in the polymer spheres react with sodium sulfamate, thereby grafting a large number of sulfonic acid groups; the polymer spheres can adsorb Lewis acid aluminum chloride to prepare the strongly acidic solid catalyst.

[0013] Further, in step A1, the dosage ratio of gelatin to deionized water is 0.02 - 0.03 g: 150 - 200 mL, and the initiator is azobisisobutyronitrile; the dosage ratio of divinylbenzene, glycerol trimethacrylate, and the initiator is 30 g: 20 - 30 g: 0.3 - 0.5 g; the dosage ratio of the oil phase mixture to the water phase mixture is 50 - 60 g: 200 g; in step A2, the dosage of the prepolymer and glycidyl methacrylate is 250 g: 10 - 20 g; the post-process treatment steps include: filtering with a Buchner funnel, then rinsing three times with deionized water to obtain bead-shaped resin; drying the bead-shaped resin in an oven at 80 °C to constant weight to obtain polymer spheres.

[0014] Further, in step A3, the dosage ratio of sodium sulfamate, water, and aluminum chloride is 3 - 5 g: 20 mL: 1.5 - 2.5 g, and the dosage ratio of the mixture to the polymer spheres is 20 g: 200 - 250 g; the post-process treatment steps include: filtering with a Buchner funnel, then rinsing three times with deionized water, and then drying in an oven at 80 °C to constant weight to obtain a strongly acidic solid catalyst.

[0015] Further, the preparation method of the modified molecular sieve includes the following steps: B1. Add ZSM-5 molecular sieve to an H2SO4 solution and impregnate for 30 - 60 min, then filter to collect the solid to obtain acidified molecular sieve. Acidifying the ZSM-5 molecular sieve with a sulfuric acid solution can enrich the acidic sites of the ZSM-5 molecular sieve.

[0016] B2. Mix toluene diisocyanate and trifluoroethanol to obtain a polyester prepolymer solution; mix the acidified molecular sieve and the polyester prepolymer solution to obtain a polyester suspension; add a curing agent to the polyester suspension, stir, degas under vacuum, and cure at 70 - 80 °C for 3 - 4 h to obtain a modified molecular sieve.

[0017] The reaction formula for the synthesis of the polyester prepolymer solution by the reaction of toluene diisocyanate and trifluoroethanol is as follows:

[0018] Further, in step B1, the concentration of the H2SO4 solution is 0.5 - 1 mol / L, and the dosage ratio of the ZSM-5 molecular sieve to the H2SO4 solution is 5.00 - 10.00 g: 100 mL; in step B2, the dosage ratio of toluene diisocyanate to trifluoroethanol is 17 - 35 g: 5 - 10 g, and the dosage ratio of the acidified molecular sieve to the polyester prepolymer solution is 2 - 5 g: 50 mL; the curing agent is methyl ethyl ketone peroxide, and the dosage ratio of the polyester suspension to the curing agent is 45 - 50 mL: 0.5 g.

[0019] Further, in step S1, the mass ratio of the strongly acidic solid catalyst to the modified molecular sieve is 1:1; the ball milling speed is 200 - 300 r / min, and the ball milling duration is 20 - 30 min.

[0020] Further, in step S2, the preparation method of the metal ionic liquid includes the following steps: 10 - 15 g of N - methylmorpholine, 5 - 20 mL of n - butyl bromide, and 50 - 100 mL of acetone are mixed and stirred to form a white solid; the white solid is vacuum filtered and dried to obtain an intermediate; 50 mL of deionized water, 10 - 15 g of the intermediate, 2.35 - 5.5 g of MgCl₂, and 1 - 2 g of AlCl₃ are mixed evenly to obtain a reactant; the reactant reacts at 70 - 80 °C for 2 - 3 h, and then the water in the reactant is removed by rotary evaporation under reduced pressure to obtain the metal ionic liquid.

[0021] Further, in step S2, the drying temperature is 100 - 110 °C, and the drying duration is 50 - 60 min.

[0022] As another aspect of the present invention, an activation catalyst for synthesizing methyl p - tert - butylformate prepared by the preparation method of the activation catalyst for synthesizing methyl p - tert - butylformate.

[0023] The present invention has the following beneficial effects: 1. The activation catalyst synthesized in the present invention is obtained by activating a strongly acidic solid catalyst and a modified molecular sieve by adding them into a metal ionic liquid. When synthesizing the strongly acidic solid catalyst, divinylbenzene and glycerol trimethacrylate monomers containing multiple double bonds are used as the backbone to synthesize high - density polymer spheres; sodium aminosulfonate is grafted onto the above - mentioned polymer spheres to enrich the number of its own sulfonic acid groups. In addition, a small amount of Lewis acid aluminum chloride can combine with sodium aminosulfonate to further enhance the acidity of the strongly acidic solid catalyst.

[0024] 2. The modified molecular sieve selects ZSM - 5 molecular sieve. The above molecular sieve belongs to the MFI topological structure and orthorhombic system; the framework structure contains two perpendicular and intersecting ten - membered ring channels. One is a straight - shaped pore opening with an elliptical ten - membered ring, and the other is a "Z" - shaped pore opening close to a circular ten - membered ring, with a pore size of 0.5 nm, and the size at the intersection of the two channels is 0.9 - 1 nm. Toluene diisocyanate and trifluoroethanol are used as polyester components, and then mixed with acidified ZSM - 5 molecular sieve to form a polyester suspension. Through the curing process, the cured polyester can firmly fix the molecular sieve particles; the uniform dispersion of the molecular sieve in the polyester can avoid its direct influence by the external environment, thereby improving the use stability and service life of the synthesized molecular sieve. And the synthesized polyester contains multiple fluorine elements, thereby improving the corrosion resistance of the synthesized modified molecular sieve.

[0025] 3. The present invention uses N-methylmorpholine and n-butyl bromide as raw materials to synthesize a Lewis acid metal ionic liquid. By adding two metal chlorides, magnesium and aluminum, a bimetallic coordination ionic liquid is prepared, which can further improve the catalytic activity of the synthesized ionic liquid. After mixing a strongly acidic solid catalyst and a modified molecular sieve and adding them together to the metal ionic liquid for activation, through subsequent process treatment, the prepared activated catalyst can further improve its own adsorption performance and catalytic efficiency. The activated catalyst synthesized by the present invention has the advantages of corrosion resistance, high catalytic efficiency, and recyclability, and is suitable for large-scale industrialized and continuous production processes of methyl p-tert-butylbenzoate. Detailed implementation manners

[0026] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0027] The ZSM-5 molecular sieve catalyst selected in Examples 4-6 of the present invention was purchased from Liaoning Raodong New Materials Co., Ltd., with a specific surface area of ≥350 m 2 / g, a crystal grain size of 0.3 - 10 μm, and a pore size of 0.5 nm.

[0028] Example 1 This example provides a preparation method of a strongly acidic solid catalyst for an activated catalyst used in the synthesis of methyl p-tert-butylformate, including the following steps: A1. In a 500 mL four-necked flask equipped with a stirrer, a condenser, and a thermometer, add 200 mL of deionized water, and then add 0.02 g of gelatin. After stirring until the gelatin is completely dissolved in the deionized water, a mixed solution is obtained; then add 1 mol / L NaOH solution to adjust the pH value of the mixed solution to 7 to prepare an aqueous phase. Mix 30 g of divinylbenzene monomer, 20 g of glycerol trimethacrylate, and 0.3 g of initiator azobisisobutyronitrile to obtain an oil phase mixture. Add 50 g of the oil phase mixture to 200 g of the aqueous phase, and stir to disperse the oil phase monomer droplets into a moderately uniform size in the aqueous phase to obtain a reaction system. Heat the reaction system to 75 °C and react at this temperature for 2 h to obtain a prepolymer.

[0029] A2. Add 250 g of the prepolymer and 10 g of glycidyl methacrylate to the four-necked flask, then heat the four-necked flask to 90 °C and keep it warm for 2 h, then stop the reaction and cool to room temperature. Filter with a Buchner funnel and wash three times with deionized water to obtain bead-shaped resin; dry the bead-shaped resin in an oven at 80 °C to constant weight, which is the polymerized sphere.

[0030] First, 3 g of sodium aminosulfonate is dissolved in 20 mL of water, and then 1.5 g of aluminum chloride is added and mixed evenly to obtain a mixture. The mixture is heated to 80 °C, and then 0.1 mol / L NaOH solution is added dropwise to adjust the pH value of the mixture to 8. 250 g of polymeric spheres are added to 20 g of the mixture, and the reaction is carried out under heat preservation for 15 h. After cooling to room temperature, the product is obtained. The product is filtered by a Buchner funnel, washed three times with deionized water, and then dried in an oven at 80 °C to constant weight to obtain a strongly acidic solid catalyst.

[0031] Example 2 This example provides a preparation method of a strongly acidic solid catalyst for an activation catalyst used in the synthesis of methyl p-tert-butylformate, including the following steps: A1. In a 500 mL four-necked flask equipped with a stirrer, a condenser and a thermometer, 200 mL of deionized water is added, and then 0.025 g of gelatin is added. After stirring until the gelatin is completely dissolved in the deionized water, a mixed solution is obtained; then 1 mol / L NaOH solution is added dropwise to adjust the pH value of the mixture to 7 to obtain an aqueous phase. 30 g of divinylbenzene monomer, 25 g of glycerol trimethacrylate and 0.4 g of initiator azobisisobutyronitrile are mixed evenly to obtain an oil-phase mixture. 55 g of the oil-phase mixture is added dropwise to 200 g of the aqueous phase, so that the oil-phase monomer droplets are dispersed into a moderately uniform size in the aqueous phase to obtain a reaction system. The reaction system is heated to 78 °C and reacted at this temperature for 2.5 h to obtain a prepolymer.

[0032] A2. 250 g of the prepolymer and 15 g of glycidyl methacrylate are added to the four-necked flask, and then the four-necked flask is heated to 92 °C and reacted under heat preservation at this temperature for 3 h. Then the reaction is stopped and cooled to room temperature. It is filtered by a Buchner funnel and washed three times with deionized water to obtain bead-shaped resin; the bead-shaped resin is dried in an oven at 80 °C to constant weight, which is the polymeric sphere.

[0033] A3. First, 4 g of sodium aminosulfonate is dissolved in 20 mL of water, and then 1.8 g of aluminum chloride is added and mixed evenly to obtain a mixture. The mixture is heated to 90 °C, and then 0.1 mol / L NaOH solution is added dropwise to adjust the pH value of the mixed solution to 9. 230 g of polymeric spheres are added to 20 g of the mixture, and the reaction is carried out under heat preservation for 18 h and cooled to room temperature. It is filtered by a Buchner funnel, washed three times with deionized water, and then dried in an oven at 80 °C to constant weight to obtain a strongly acidic solid catalyst.

[0034] Example 3 This example provides a preparation method of a strongly acidic solid catalyst for an activation catalyst used in the synthesis of methyl p-tert-butylformate, including the following steps: A1. In a 500 mL four-necked flask equipped with a stirrer, a condenser and a thermometer, 200 mL of deionized water was added, and then 0.03 g of gelatin was added. After stirring until the gelatin was completely dissolved in the deionized water, a mixed solution was obtained. Then, 1 mol / L NaOH solution was added dropwise to adjust the pH value of the mixture to 7, obtaining an aqueous phase. 30 g of divinylbenzene monomer, 30 g of glycerol trimethacrylate and 0.5 g of initiator azobisisobutyronitrile were mixed evenly to obtain an oil-phase mixture. 60 g of the oil-phase mixture was added dropwise to 200 g of the aqueous phase, so that the oil-phase monomer droplets were dispersed into a moderately uniform size in the aqueous phase, obtaining a reaction system. The reaction system was heated to 80 °C and reacted at this temperature for 3 h to obtain a prepolymer.

[0035] A2. 250 g of the prepolymer and 20 g of glycidyl methacrylate were added to the four-necked flask, and then the four-necked flask was heated to 95 °C and kept reacting at this temperature for 4 h. Then the reaction was stopped and cooled to room temperature. Filtration was carried out with a Buchner funnel, and then rinsed three times with deionized water to obtain bead-shaped resin; the bead-shaped resin was dried to constant weight in an oven at 80 °C, which was the polymerized sphere.

[0036] A3. 5 g of sodium sulfamate was first dissolved in 20 mL of water, and then 2.5 g of aluminum chloride was added and mixed evenly to obtain a mixture. The mixture was heated to 100 °C, and then 0.1 mol / L NaOH solution was added dropwise to adjust the pH value of the mixed solution to 10. 200 g of the polymerized sphere was added to 20 g of the mixture, and the reaction was carried out under insulation for 20 h and then cooled to room temperature. Filtration was carried out with a Buchner funnel, and then rinsed three times with deionized water, and then placed in an oven at 80 °C and dried to constant weight to obtain a strongly acidic solid catalyst.

[0037] Example 4 This example provides a preparation method of a modified molecular sieve for an activation catalyst used in the synthesis of methyl p-tert-butylformate, including the following steps: B1. 5.00 g of ZSM-5 molecular sieve was accurately measured, and then the above molecular sieve solid was added to 0.5 mol / L, 100 mL of H2SO4 solution and impregnated for 30 min, and then filtered to collect the solid to obtain an acidified molecular sieve.

[0038] B2. 17 g of toluene diisocyanate and 5 g of trifluoroethanol were mixed evenly to obtain a polyester prepolymer solution. Then, 2 g of the acidified molecular sieve and 50 mL of the polyester prepolymer solution were mixed and magnetically stirred until evenly mixed to obtain a polyester suspension; 0.5 g of curing agent methyl ethyl ketone peroxide was added to 45 mL of the polyester suspension, and stirring was continued for 5 min; after stirring was completed, it was poured into a rubber mold for vacuum degassing and cured at 70 °C for 3 h to synthesize a modified molecular sieve.

[0039] Example 5 This embodiment provides a preparation method of a modified molecular sieve for an activating catalyst used in the synthesis of methyl p-tert-butylformate, including the following steps: B1. Accurately measure 8.00 g of ZSM-5 molecular sieve, then add the above molecular sieve solid to 100 mL of 0.8 mol / L H2SO4 solution and impregnate for 50 min, then filter to collect the solid to obtain an acidified molecular sieve.

[0040] B2. Mix 25 g of toluene diisocyanate and 8 g of trifluoroethanol to obtain a polyester prepolymer solution. Then mix 3 g of the acidified molecular sieve and 50 mL of the polyester prepolymer solution, and stir magnetically until evenly mixed to obtain a polyester suspension; add 0.5 g of curing agent methyl ethyl ketone peroxide to 48 mL of the polyester suspension, and continue to stir for 6 min; after stirring is completed, pour it into a rubber mold for vacuum degassing, and cure at 75 °C for 3.5 h to synthesize the modified molecular sieve.

[0041] Example 6 This embodiment provides a preparation method of a modified molecular sieve for an activating catalyst used in the synthesis of methyl p-tert-butylformate, including the following steps: B1. Accurately measure 10.00 g of ZSM-5 molecular sieve, then add the above molecular sieve solid to 100 mL of 1 mol / L H2SO4 solution and impregnate for 60 min, then filter to collect the solid to obtain an acidified molecular sieve.

[0042] B2. Mix 35 g of toluene diisocyanate and 10 g of trifluoroethanol to obtain a polyester prepolymer solution. Then mix 5 g of the acidified molecular sieve and 50 mL of the polyester prepolymer solution, and stir magnetically until evenly mixed to obtain a polyester suspension; add 0.5 g of curing agent methyl ethyl ketone peroxide to 50 mL of the polyester suspension, and continue to stir for 10 min; after stirring is completed, pour it into a rubber mold for vacuum degassing, and cure at 80 °C for 4 h to synthesize the modified molecular sieve.

[0043] Example 7 This embodiment provides a preparation method of an activating catalyst used in the synthesis of methyl p-tert-butylformate, including the following steps: S1. Add 10 g of N-methylmorpholine, 15 mL of n-butyl bromide and 50 mL of acetone to a 250 mL beaker, and stir at 45 °C until a white solid precipitates. Vacuum filter and dry the solid to obtain an intermediate. Under a nitrogen atmosphere, add 50 mL of deionized water, 10 g of the intermediate, 2.35 g of MgCl2 and 1 g of AlCl3 to a 250 mL three-necked flask, and mix evenly to obtain a reactant. The reactant reacts at 70 °C for 2 h, and then the water in the reactant is removed by rotary evaporation under reduced pressure to synthesize a metal ionic liquid.

[0044] S2. Mix the strongly acidic solid catalyst prepared in Example 1 and the modified molecular sieve prepared in Example 4 in a mass ratio of 1:1, add them to a ball mill tank, and ball mill at 200 r / min for 20 min to obtain a mixed material. The mixed material is impregnated in the metal ionic liquid for 30 min, and the mass ratio of the mixed material to the metal ionic liquid is 1:10. After impregnation is completed, filter to obtain a solid. The solid is transferred to a tabletting machine for cold pressing to obtain a pre-pressed block. The pre-pressed block is transferred to a vacuum drying oven and dried at 100 °C for 50 min to obtain a dried block; after the dried block is naturally cooled to room temperature, the impregnated catalyst for synthesizing methyl p-tert-butylformate is obtained.

[0045] Example 8 This example provides a preparation method of an activated catalyst for synthesizing methyl p-tert-butylformate, including the following steps: S1. Add 12 g of N-methylmorpholine, 18 mL of n-butyl bromide, and 70 mL of acetone to a 250 mL beaker, and stir at 48 °C until a white solid precipitates. Vacuum filter and dry the solid to obtain an intermediate. Under a nitrogen atmosphere, add 50 mL of deionized water, 12 g of the intermediate, 3.5 g of MgCl2, and 1.5 g of AlCl3 to a 250 mL three-necked flask, mix well to obtain a reactant. The reactant reacts at 77 °C for 2.6 h, and then the water in the reactant is removed by rotary evaporation under reduced pressure to synthesize the metal ionic liquid.

[0046] S2. Mix the strongly acidic solid catalyst prepared in Example 2 and the modified molecular sieve prepared in Example 5 in a mass ratio of 1:1, add them to a ball mill tank, and ball mill at 250 r / min for 26 min to obtain a mixed material. The mixed material is impregnated in the metal ionic liquid for 50 min, and the mass ratio of the mixed material to the metal ionic liquid is 1:12. After impregnation is completed, filter to obtain a solid. The solid is transferred to a tabletting machine for cold pressing to obtain a pre-pressed block. The pre-pressed block is transferred to a vacuum drying oven and dried at 105 °C for 55 min to obtain a dried block; after the dried block is naturally cooled to room temperature, the impregnated catalyst for synthesizing methyl p-tert-butylformate is obtained.

[0047] Example 9 This example provides a preparation method of an activated catalyst for synthesizing methyl p-tert-butylformate, including the following steps: S1. 15 g of N-methylmorpholine, 20 mL of n-butyl bromide, and 100 mL of acetone were added to a 250 mL beaker and stirred at 50 °C until a white solid precipitated. The solid was vacuum filtered and dried to obtain an intermediate. Under a nitrogen atmosphere, 50 mL of deionized water, 15 g of the intermediate, 5.5 g of MgCl₂, and 2 g of AlCl₃ were added to a 250 mL three-necked flask, mixed well to obtain a reactant. The reactant was reacted at 80 °C for 3 h, and then the water in the reactant was removed by rotary evaporation under reduced pressure to synthesize a metal ionic liquid.

[0048] S2. The strongly acidic solid catalyst prepared in Example 3 and the modified molecular sieve prepared in Example 6 were mixed in a mass ratio of 1:1 and added to a ball mill jar, and ball milled at 300 r / min for 30 min to obtain a mixed material. The mixed material was immersed in the metal ionic liquid for 60 min, and the mass ratio of the mixed material to the metal ionic liquid was 1:15. After immersion, filtration was carried out to obtain a solid. The solid was transferred to a tablet press for cold pressing to obtain a pre-pressed block. The pre-pressed block was transferred to a vacuum drying oven and dried at 100 °C for 50 min to obtain a dried block; after the dried block was naturally cooled to room temperature, an impregnated catalyst for methyl p-tert-butylbenzoate was synthesized.

[0049] Comparative Example 1 The difference between this comparative example and Example 3 is that when synthesizing the strongly acidic solid catalyst, in step A1, when preparing the prepolymer, trimethylolpropane trimethacrylate was replaced with styrene of the same amount of substance.

[0050] Comparative Example 2 The difference between this comparative example and Example 9 is that when synthesizing the modified molecular sieve, trifluoroethanol was replaced with ethylene glycol of the same mass.

[0051] Comparative Example 3 The difference between this comparative example and Example 9 is that when synthesizing the active catalyst, magnesium chloride and aluminum chloride were replaced with cobalt chloride hexahydrate and tin chloride of the same molar amount.

[0052] Performance detection: 1. The acid amount of the strongly acidic solid catalysts prepared in Examples 1-3 and Comparative Example 1 was measured by the n-butylamine titration method, and the test results are shown in Table 1 below: Table 1 - Performance detection data table of samples

[0053] Data analysis: By comparing and analyzing the data in Table 1 above, the acid content of the strongly acidic solid catalysts prepared in Examples 1-3 of the present invention is relatively high. However, in Comparative Example 1, trimethylolpropane trimethacrylate was replaced with styrene of the same amount of substance, resulting in a reduction in the double bonds in the prepared catalyst, a decrease in the amount of glycidyl methacrylate grafted, and further a decrease in the number of epoxy groups capable of reacting with sodium sulfamate, thus reducing the solid acid amount of the prepared strongly acidic solid catalyst.

[0054] 2. In the industrial production of continuously synthesizing methyl p-tert-butylbenzoate using toluene and isobutene as raw materials, during the esterification stage, when p-tert-butylbenzoic acid and methanol react to synthesize the crude product of methyl p-tert-butylbenzoate, the activated catalysts prepared in Examples 7-9 and Comparative Examples 2-3 are added in sequence to obtain the crude product of methyl p-tert-butylbenzoate. Among them, the dosage ratio of p-tert-butylbenzoic acid, methanol and the activated catalyst is 1500 kg: 75 kg: 1.5 m 3 . After one month of continuous process, the conversion rates of the methyl p-tert-butylbenzoates synthesized in Examples 7-9 and Comparative Examples 2-3 are detected in sequence by acid-base titration.

[0055] Table 2 - Data sheet for performance detection of samples

[0056] Data analysis: The conversion rates of the methyl p-tert-butylbenzoates finally synthesized by the activated catalysts for synthesizing methyl p-tert-butylbenzoate used in Examples 7-9 of the present invention are relatively high, all reaching more than 99%. However, when synthesizing the modified molecular sieve using the activated catalyst prepared in Comparative Example 2, ethylene glycol was used to replace trifluoroethanol of the same mass, reducing the wear resistance and corrosion resistance of the synthesized modified molecular sieve. It is shown that after one cycle of continuous process, the activated catalyst prepared in Comparative Example 2 is significantly deactivated, manifested as a significant decrease in the conversion rate of methyl p-tert-butylbenzoate.

[0057] In Comparative Example 3, when synthesizing the activated catalyst, the coordination metals aluminum and magnesium were replaced with cobalt and tin metal elements. In the present invention, aluminum chloride and magnesium chloride have higher catalytic activities, manifested as a decrease in the conversion rate of the activated catalyst synthesized in Comparative Example 3.

[0058] The above content is only an example and illustration of the structure of the present invention. Those skilled in the art of the present technology make various modifications or supplements to the described specific embodiments or use similar methods for substitution, as long as they do not deviate from the structure of the invention or exceed the scope defined by this claim book, they should all fall within the protection scope of the present invention.

[0059] In the description of this specification, the descriptions referring to the terms "one embodiment", "example", "specific example", etc. mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0060] The preferred embodiments of the present invention disclosed above are only used to help explain the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the present invention to only the specific implementation manners. Obviously, according to the content of this specification, many modifications and changes can be made. These embodiments are selected and specifically described in this specification in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can well understand and utilize the present invention. The present invention is only limited by the claims and their full scope and equivalents.

Claims

1. A method for preparing an activated catalyst for synthesizing methyl tert-butyl formate, characterized in that: The following steps are involved: S1, mixing and ball-milling a strongly acidic solid catalyst and a modified molecular sieve to obtain a mixture; S2. The mixed material is added into a metal ion liquid for activation, and then filtered to obtain a solid; the solid is cold-pressed to obtain a pre-pressed block; the pre-pressed block is dried and then naturally cooled to obtain an activated catalyst for synthesizing methyl p-tert-butyl formate.

2. The method for preparing an activated catalyst for synthesizing methyl tert-butyl formate according to claim 1, wherein: In step S1, the method for preparing the strongly acidic solid catalyst comprises the following steps: A1. Gelatin is completely dissolved in deionized water to obtain a mixed solution, and then a NaOH solution is added dropwise to adjust the pH value of the mixed solution to 7 to obtain an aqueous phase; divinylbenzene, trimethacrylate glycerol and an initiator are mixed to obtain an oil phase mixture; the oil phase mixture is added to the aqueous phase to obtain a reaction system; the reaction system is heated to 75-80° C., and reacted at this temperature for 2-3 hours to obtain a prepolymer; A2, adding glycidyl methacrylate to the prepolymer, then heating to 90-95°C, keeping the temperature at this temperature for 2-4 hours, then stopping the reaction, cooling to room temperature, and performing post-processing to obtain polymer spheres; A3, sodium aminosulfonate is first dissolved in water, and then aluminum chloride is added and mixed to obtain a mixture; the mixture is heated to 80-100°C, and a NaOH solution is added dropwise to adjust the pH value of the mixture to 8-10, and then polymer spheres are added, and the mixture is kept warm at 80-100°C for 15-20 hours. After post-processing, a strongly acidic solid catalyst is prepared.

3. The method for preparing an activated catalyst for synthesizing methyl tert-butyl formate according to claim 2, wherein: In step A1, the amount ratio of gelatin to deionized water is 0.02-0.03g:150-200mL, and the initiator is azobisisobutyronitrile; the amount ratio of divinylbenzene, trimethacrylate glycerol and initiator is 30g:20-30g:0.3-0.5g; the amount ratio of the oil phase mixture to the water phase mixture is 50-60g:200g; in step A2, the amount of the prepolymer and glycidyl methacrylate is 250g:10-20g; The post-processing steps include: filtering with a Buchner funnel, and then rinsing with deionized water three times to obtain a beaded resin; The beaded resin was dried in an oven at 80°C to constant weight to obtain polymeric spheres.

4. The method for preparing an activated catalyst for synthesizing methyl tert-butyl formate according to claim 2, wherein: In step A3, the ratio of sodium sulfamate, water and aluminum chloride is 3-5g:20mL:1.5-2.5g, and the ratio of the mixture to the polymer sphere is 20g:200-250g; the post-processing step includes: filtering with a Buchner funnel, rinsing three times with deionized water, and then drying in an oven at 80°C to constant weight to obtain a strongly acidic solid catalyst.

5. The method for preparing an activated catalyst for synthesizing methyl p-tert-butylformate according to claim 1, wherein: The preparation method of the modified molecular sieve comprises the following steps: B1. Add ZSM-5 molecular sieve into H2SO4 solution and soak for 30-60 minutes, then filter and collect the solid to obtain the acidified molecular sieve; B2, toluene diisocyanate and trifluoroethanol are mixed to obtain a polyester prepolymer liquid; the acidified molecular sieve and the polyester prepolymer liquid are mixed to obtain a polyester suspension; a curing agent is added to the polyester suspension, stirred, vacuum degassed, and cured at 70-80°C for 3-4h to obtain a modified molecular sieve.

6. The method for preparing an activated catalyst for synthesizing methyl tert-butyl formate according to claim 5, characterized in that: In step B1, the concentration of H2SO4 solution is 0.5-1mol / L, and the usage ratio of ZSM-5 molecular sieve and H2SO4 solution is 5.00-10.00g:100mL; in step B2, the usage ratio of toluene diisocyanate and trifluoroethanol is 17-35g:5-10g, and the usage ratio of acidified molecular sieve and polyester prepolymer liquid is 2-5g:50mL; the curing agent is methyl isobutyl ketone peroxide, and the usage ratio of polyester suspension and curing agent is 45-50mL:0.5g.

7. The method for preparing an activated catalyst for synthesizing methyl p-tert-butylformate according to claim 1, characterized in that: In step S1, the mass ratio of the strongly acidic solid catalyst to the modified molecular sieve is 1:1; the ball milling speed is 200-300 r / min, and the ball milling time is 20-30 min.

8. The method for preparing an activated catalyst for synthesizing methyl p-tert-butylformate according to claim 1, characterized in that: In step S2, the method for preparing the metal ionic liquid comprises the following steps: 10-15 g of N-methylmorphine, 5-20 mL of n-butyl bromide and 50-100 mL of acetone are mixed and stirred to generate a white solid; the white solid is vacuum filtered and dried to obtain an intermediate; 50 mL of deionized water, 10-15 g of the intermediate, 2.35-5.5 g of MgCl2 and 1-2 g of AlCl3 are mixed to obtain a reactant; the reactant is reacted at 70-80° C. for 2-3 h, and then water in the reactant is removed by reduced pressure rotary evaporation to obtain a metal ion liquid.

9. The method for preparing an activated catalyst for synthesizing methyl tert-butyl formate according to claim 1, characterized in that: In step S2, the drying temperature is 100-110°C and the drying time is 50-60 minutes.

10. An activated catalyst for synthesizing methyl p-tert-butyl formate, characterized in that: The catalyst is prepared by adopting a preparation method of an activated catalyst for synthesizing methyl p-tert-butyl formate.

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