Crude ester purification process of n-butyl acetate
By adding citric acid to the molecular sieve and using aluminum-zirconium coupling agent, the composite catalyst was prepared, and the side reaction and purity problems in n-butyl acetate synthesis were solved, and higher esterification and product purity were achieved.
Patent Information
- Application Number
- CN202411235189.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-04
- Publication Date
- 2024-12-10
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of n-butyl acetate processing and relates to a crude ester purification process of n-butyl acetate. Background Art
[0002] n-Butyl acetate, a colorless, transparent, flammable liquid with an aromatic odor, is an important member of organic chemical products. It has been widely used in the synthesis of coatings, fragrances, leather, plastics and pharmaceutical intermediates, and has significant value and significance. At present, industrial production mainly relies on concentrated sulfuric acid to catalyze the reaction of acetic acid and n-butanol to synthesize n-butyl acetate. However, this process has problems such as increased side reactions, decreased product purity, increased equipment corrosion and serious environmental pollution.
[0003] Molecular sieves are widely used in many fields such as catalysis, adsorption and separation due to their large specific surface area, rich pore structure, good hydrothermal stability and adjustable surface acidity. As catalysts, molecular sieves have shown excellent catalytic performance in key industrial reactions such as catalytic cracking, isomerization and aromatization. However, the stability of molecular sieves needs to be improved, and the types of molecular sieves reported so far are relatively limited, such as ZSM molecular sieves, MCM molecular sieves, β molecular sieves, mordenite, etc., and related research reports are not sufficient. Summary of the invention
[0004] The object of the present invention is to provide a crude ester purification process of n-butyl acetate. In the preparation of molecular sieves, citric acid is added to expand its pore structure, increase active sites, and improve the conversion efficiency of n-butyl acetate. The aluminum zirconium coupling agent is modified to make the pores richer. Amino acids promote the adhesion of phosphotungstic acid to the surface, avoid agglomeration, and evenly disperse. At the same time, the molecular sieve is reinforced to ensure the stability of the catalyst. The composite catalyst prepared by the present invention has a higher esterification rate for the preparation of n-butyl acetate, can effectively reduce the occurrence of side reactions, and thus help to improve the purity of the n-butyl acetate product.
[0005] The purpose of the present invention can be achieved by the following technical solutions:
[0006] A crude ester purification process of n-butyl acetate, the purification process comprising the following steps:
[0007] After adding glacial acetic acid and n-butanol to the composite catalyst and mixing evenly, heating and stirring are performed and then water-cooling is performed to obtain n-butyl acetate; the mass ratio of the composite catalyst, glacial acetic acid and n-butanol is 0.02-0.04:1.3-1.4:3.2-3.5, and the heating and stirring is performed at a temperature of 110-120°C for 2-3h.
[0008] As a preferred technical solution of the present invention, the preparation method of the composite catalyst comprises the following steps:
[0009] 1) adding molecular sieve particles to anhydrous ethanol and deionized water, stirring and mixing, adjusting the pH value, adding a silane coupling agent, heating and stirring, washing, filtering, and drying to obtain a preform;
[0010] 2) The preform, amino acid and deionized water are mixed, and then phosphotungstic acid is added, heated and stirred, and then placed in an oven for drying and ground to obtain a composite catalyst.
[0011] As a preferred technical solution of the present invention, in step 1), the mass ratio of molecular sieve particles, ethanol solution and silane coupling agent is 3-5:80-90:0.6-0.8; the pH value is adjusted to 4.0-4.2; the heating and stirring is stirred at 70-75°C for 6-8h; the washing is alternating washing with ethanol and deionized water for 3 times each; and the drying is dried at 120-130°C to constant weight.
[0012] As a preferred technical solution of the present invention, the silane coupling agent is one or both of silane coupling agent KH550 and silane coupling agent KH560; the concentration of the ethanol solution is 50-60%
[0013] As a preferred technical solution of the present invention, in step 2), the mass ratio of the preform, amino acid, deionized water and phosphotungstic acid is 10-12:0.10-0.12:30-40:2-3; the heating and stirring is evaporation at a temperature of 70-75°C until there is no water; the drying is drying at a temperature of 110°C to constant weight; in the embodiments and comparative examples of the present invention, the amino acid is L-cysteine.
[0014] As a preferred technical solution of the present invention, the method for preparing the molecular sieve particles comprises the following steps:
[0015] S1: Anhydrous ethanol, a template agent and deionized water are mixed and stirred, and ethyl orthosilicate is slowly added and stirred to obtain a mixture;
[0016] S2: The mixture is transferred to a reactor equipped with a polytetrafluoroethylene liner for crystallization treatment, washed and centrifuged, the solid is taken, and citric acid solution is added for soaking. After removing the solution, aluminum zirconium coupling agent and anhydrous ethanol are added and stirred, and then placed in an oven for drying to constant weight and then heated and calcined to obtain molecular sieve particles.
[0017] As a preferred technical solution of the present invention, in step S1, the mass ratio of anhydrous ethanol, template, deionized water and tetraethyl orthosilicate is 10-12:2.7-3:23-25:2-3; the template is a mixture of n-butylamine and tetrabutylammonium hydroxide in a mass ratio of 0.3:1;
[0018] As a preferred technical solution of the present invention, in step S2, the crystallization treatment is performed at a temperature of 172-180°C for 2 days; the immersion time is 1 hour; the stirring and mixing is performed at 40-50°C for 30-45 minutes; the drying is performed at a temperature of 110°C to constant weight; and the heating and calcination is performed at a temperature of 310-350°C for 3-3.5 hours.
[0019] As a preferred technical solution of the present invention, in step S2, the mass ratio of the citric acid solution, the mixture, the aluminum zirconium coupling agent and anhydrous ethanol is 20:10-12:3-4:35-45; the aluminum zirconium coupling agent is aluminum zirconium coupling agent LD-139; and the concentration of the citric acid solution is 1.2 g / L.
[0020] Beneficial effects of the present invention:
[0021] In the process of preparing molecular sieves, the present invention adopts the method of adding citric acid before the molecular sieve is solidified to promote the further expansion of its internal pore structure, thereby obtaining more active sites to improve the conversion efficiency of n-butyl acetate. The molecular sieve modified by aluminum zirconium coupling agent has a richer pore structure. When phosphotungstic acid is attached to the surface of the molecular sieve, it can avoid agglomeration and can be evenly dispersed in the pores. In addition, the electrostatic adsorption of amino acids and phosphotungstic acid promotes the attachment of phosphotungstic acid to the surface of the molecular sieve, increases its attachment amount and adhesion, is more catalytically active and is not easy to lose, thereby ensuring the stability of the catalyst, and can effectively reduce the occurrence of side reactions, thereby helping to improve the purity of the n-butyl acetate product. DETAILED DESCRIPTION
[0022] In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the specific implementation methods, structures, features and effects of the present invention are described in detail below in combination with the embodiments.
[0023] Example 1
[0024] A crude ester purification process of n-butyl acetate, the purification process comprising the following steps:
[0025] After adding glacial acetic acid and n-butanol to the composite catalyst and mixing evenly, heating and stirring are performed and then water-cooling is performed to obtain n-butyl acetate; the mass ratio of the composite catalyst, glacial acetic acid and n-butanol is 0.02:1.3:3.2, and the heating and stirring is performed at a temperature of 110°C for 2 hours.
[0026] The preparation method of the composite catalyst comprises the following steps:
[0027] 1) adding molecular sieve particles to anhydrous ethanol and deionized water, stirring and mixing, adjusting the pH value, adding a silane coupling agent, heating and stirring, washing, filtering, and drying to obtain a preform;
[0028] In step 1), the mass ratio of molecular sieve particles, ethanol solution and silane coupling agent is 3:80:0.6; the pH value is adjusted to 4.0; the heating and stirring is stirred at 70°C for 6 hours; the washing is ethanol and deionized water for 3 times each; the drying is dried at 120°C to constant weight; the silane coupling agent is silane coupling agent KH550; the concentration of the ethanol solution is 50%;
[0029] 2) mixing the preform, amino acid and deionized water, then adding phosphotungstic acid, heating and stirring, placing in an oven for drying, and grinding to obtain a composite catalyst;
[0030] In step 2), the mass ratio of the preform, amino acid, deionized water and phosphotungstic acid is 10:0.10:30:2; the heating and stirring is evaporation at 70°C until there is no water; and the drying is drying at 110°C to constant weight.
[0031] The method for preparing the molecular sieve particles comprises the following steps:
[0032] S1: Anhydrous ethanol, a template agent and deionized water are mixed and stirred, and ethyl orthosilicate is slowly added and stirred to obtain a mixture;
[0033] In step S1, the mass ratio of anhydrous ethanol, template, deionized water and tetraethyl orthosilicate is 10:2.7:23:2; the template is a mixture of n-butylamine and tetrabutylammonium hydroxide in a mass ratio of 0.3:1;
[0034] S2: The mixture is transferred to a reactor equipped with a polytetrafluoroethylene liner for crystallization treatment, washed and centrifuged, the solid is taken, and citric acid solution is added for soaking, the solution is removed, aluminum zirconium coupling agent and anhydrous ethanol are added, stirred and mixed, placed in an oven for drying to constant weight, and then heated and calcined to obtain molecular sieve particles;
[0035] In step S2, the crystallization treatment is performed at 172°C for 2 days; the immersion time is 1 hour; the stirring and mixing is performed at 40°C for 30 minutes; the drying is performed at 110°C to constant weight; the heating and calcination is performed at 310°C for 3 hours; the mass ratio of the citric acid solution, the mixture, the aluminum zirconium coupling agent and anhydrous ethanol is 20:10:3:35; the aluminum zirconium coupling agent is aluminum zirconium coupling agent LD-139; and the concentration of the citric acid solution is 1.2 g / L.
[0036] Example 2
[0037] A crude ester purification process of n-butyl acetate, the purification process comprising the following steps:
[0038] After adding glacial acetic acid and n-butanol to the composite catalyst and mixing evenly, heating and stirring are performed and then water-cooling is performed to obtain n-butyl acetate; the mass ratio of the composite catalyst, glacial acetic acid and n-butanol is 0.027:1.33:3.3, and the heating and stirring is performed at a temperature of 113° C. and stirring for 2.3 hours.
[0039] The preparation method of the composite catalyst comprises the following steps:
[0040] 1) adding molecular sieve particles to anhydrous ethanol and deionized water, stirring and mixing, adjusting the pH value, adding a silane coupling agent, heating and stirring, washing, filtering, and drying to obtain a preform;
[0041] In step 1), the mass ratio of molecular sieve particles, ethanol solution and silane coupling agent is 3.7:83:0.67; the pH value is adjusted to 4.1; the heating and stirring is stirred at 72° C. for 6.7 hours; the washing is alternating washing with ethanol and deionized water for 3 times each; the drying is dried at 123° C. to constant weight; the silane coupling agent is silane coupling agent KH550; the concentration of the ethanol solution is 53%;
[0042] 2) mixing the preform, amino acid and deionized water, then adding phosphotungstic acid, heating and stirring, placing in an oven for drying, and grinding to obtain a composite catalyst;
[0043] In step 2), the mass ratio of the preform, amino acid, deionized water and phosphotungstic acid is 10.7:0.11:33:2.3; the heating and stirring is evaporation at 72°C until there is no water; and the drying is drying at 110°C to constant weight.
[0044] The method for preparing the molecular sieve particles comprises the following steps:
[0045] S1: Anhydrous ethanol, a template agent and deionized water are mixed and stirred, and ethyl orthosilicate is slowly added and stirred to obtain a mixture;
[0046] In step S1, the mass ratio of anhydrous ethanol, template, deionized water and tetraethyl orthosilicate is 10.7:2.8:23.7:2.3; the template is a mixture of n-butylamine and tetrabutylammonium hydroxide in a mass ratio of 0.3:1;
[0047] S2: The mixture is transferred to a reactor equipped with a polytetrafluoroethylene liner for crystallization treatment, washed and centrifuged, the solid is taken, and citric acid solution is added for soaking, the solution is removed, aluminum zirconium coupling agent and anhydrous ethanol are added, stirred and mixed, placed in an oven for drying to constant weight, and then heated and calcined to obtain molecular sieve particles;
[0048] In step S2, the crystallization treatment is performed at 175°C for 2 days; the immersion time is 1 hour; the stirring and mixing is performed at 43°C for 35 minutes; the drying is performed at 110°C to constant weight; the heating and calcination is performed at 323°C for 3.2 hours; the mass ratio of the citric acid solution, the mixture, the aluminum zirconium coupling agent and the anhydrous ethanol is 20:10.7:3.3:38; the aluminum zirconium coupling agent is the aluminum zirconium coupling agent LD-139; and the concentration of the citric acid solution is 1.2 g / L.
[0049] Example 3
[0050] A crude ester purification process of n-butyl acetate, the purification process comprising the following steps:
[0051] After adding glacial acetic acid and n-butanol to the composite catalyst and mixing evenly, heating and stirring are performed and then water-cooling is performed to obtain n-butyl acetate; the mass ratio of the composite catalyst, glacial acetic acid and n-butanol is 0.033:1.37:3.4, and the heating and stirring is performed at a temperature of 117°C for 2.7 hours.
[0052] The preparation method of the composite catalyst comprises the following steps:
[0053] 1) adding molecular sieve particles to anhydrous ethanol and deionized water, stirring and mixing, adjusting the pH value, adding a silane coupling agent, heating and stirring, washing, filtering, and drying to obtain a preform;
[0054] In step 1), the mass ratio of molecular sieve particles, ethanol solution and silane coupling agent is 4.3:87:0.73; the pH value is adjusted to 4.13; the heating and stirring is stirred at 73°C for 7.3h; the washing is ethanol and deionized water for 3 times each; the drying is dried at 127°C to constant weight; the silane coupling agent is silane coupling agent KH550; the concentration of the ethanol solution is 57%;
[0055] 2) mixing the preform, amino acid and deionized water, then adding phosphotungstic acid, heating and stirring, placing in an oven for drying, and grinding to obtain a composite catalyst;
[0056] In step 2), the mass ratio of the preform, amino acid, deionized water and phosphotungstic acid is 11.3:0.11:37:2.7; the heating and stirring is evaporation at 73°C until there is no water; and the drying is drying at 110°C to constant weight.
[0057] The method for preparing the molecular sieve particles comprises the following steps:
[0058] S1: Anhydrous ethanol, a template agent and deionized water are mixed and stirred, and ethyl orthosilicate is slowly added and stirred to obtain a mixture;
[0059] In step S1, the mass ratio of anhydrous ethanol, template, deionized water and tetraethyl orthosilicate is 11.3:2.9:24.3:2.7; the template is a mixture of n-butylamine and tetrabutylammonium hydroxide in a mass ratio of 0.3:1;
[0060] S2: The mixture is transferred to a reactor equipped with a polytetrafluoroethylene liner for crystallization treatment, washed and centrifuged, the solid is taken, and citric acid solution is added for soaking, the solution is removed, aluminum zirconium coupling agent and anhydrous ethanol are added, stirred and mixed, placed in an oven for drying to constant weight, and then heated and calcined to obtain molecular sieve particles;
[0061] In step S2, the crystallization treatment is performed at 177°C for 2 days; the immersion time is 1 hour; the stirring and mixing is performed at 47°C for 40 minutes; the drying is performed at 110°C to constant weight; the heating and calcination is performed at 337°C for 3.3 hours; the mass ratio of the citric acid solution, the mixture, the aluminum zirconium coupling agent and the anhydrous ethanol is 20:11.3:3.7:42; the aluminum zirconium coupling agent is the aluminum zirconium coupling agent LD-139; and the concentration of the citric acid solution is 1.2 g / L.
[0062] Example 4
[0063] A crude ester purification process of n-butyl acetate, the purification process comprising the following steps:
[0064] After adding glacial acetic acid and n-butanol to the composite catalyst and mixing evenly, heating and stirring are performed and then water-cooling is performed to obtain n-butyl acetate; the mass ratio of the composite catalyst, glacial acetic acid and n-butanol is 0.04:1.4:3.5, and the heating and stirring is performed at a temperature of 120°C for 3 hours.
[0065] The preparation method of the composite catalyst comprises the following steps:
[0066] 1) adding molecular sieve particles to anhydrous ethanol and deionized water, stirring and mixing, adjusting the pH value, adding a silane coupling agent, heating and stirring, washing, filtering, and drying to obtain a preform;
[0067] In step 1), the mass ratio of molecular sieve particles, ethanol solution and silane coupling agent is 5:90:0.8; the pH value is adjusted to 4.2; the heating and stirring is stirred at 75°C for 8 hours; the washing is ethanol and deionized water for 3 times each; the drying is dried at 130°C to constant weight; the silane coupling agent is silane coupling agent KH550; the concentration of the ethanol solution is 60%;
[0068] 2) mixing the preform, amino acid and deionized water, then adding phosphotungstic acid, heating and stirring, placing in an oven for drying, and grinding to obtain a composite catalyst;
[0069] In step 2), the mass ratio of the preform, amino acid, deionized water and phosphotungstic acid is 12:0.12:40:3; the heating and stirring is evaporation at 75°C until there is no water; and the drying is drying at 110°C to constant weight.
[0070] The method for preparing the molecular sieve particles comprises the following steps:
[0071] S1: Anhydrous ethanol, a template agent and deionized water are mixed and stirred, and ethyl orthosilicate is slowly added and stirred to obtain a mixture;
[0072] In step S1, the mass ratio of anhydrous ethanol, template, deionized water and tetraethyl orthosilicate is 12:3:25:3; the template is a mixture of n-butylamine and tetrabutylammonium hydroxide in a mass ratio of 0.3:1;
[0073] S2: The mixture is transferred to a reactor equipped with a polytetrafluoroethylene liner for crystallization treatment, washed and centrifuged, the solid is taken, and citric acid solution is added for soaking. After removing the solution, aluminum zirconium coupling agent and anhydrous ethanol are added and stirred, and then placed in an oven for drying to constant weight and then heated and calcined to obtain molecular sieve particles.
[0074] In step S2, the crystallization treatment is performed at 180°C for 2 days; the immersion time is 1 hour; the stirring and mixing is performed at 50°C for 45 minutes; the drying is performed at 110°C to constant weight; the heating and calcination is performed at 350°C for 3.5 hours; the mass ratio of the citric acid solution, the mixture, the aluminum zirconium coupling agent and the anhydrous ethanol is 20:12:4:45; the aluminum zirconium coupling agent is the aluminum zirconium coupling agent LD-139; and the concentration of the citric acid solution is 1.2 g / L.
[0075] Comparative Example 1
[0076] Compared with Example 4, the difference in Comparative Example 1 is that, in step 1), no citric acid solution is added for soaking, and the silane coupling agent is directly added, and the other components, preparation steps and parameters are the same.
[0077] Comparative Example 2
[0078] Compared with Example 4, the difference in Comparative Example 2 is that no aluminum zirconium coupling agent is added in step S2, and the other components, preparation steps and parameters are the same.
[0079] Comparative Example 3
[0080] Compared with Example 4, the difference in Comparative Example 3 is that an aluminate coupling agent is used in step S2 instead of an aluminum zirconium coupling agent, and the other components, preparation steps and parameters are the same.
[0081] Comparative Example 4
[0082] Compared with Example 4, the difference of Comparative Example 4 is that tetrapropyl zirconate is used in step S2 instead of aluminum zirconium coupling agent, and the other components, preparation steps and parameters are the same.
[0083] Comparative Example 5
[0084] Compared with Example 4, the difference in Comparative Example 5 is that no amino acid is used in step 2), and the other components, preparation steps and parameters are the same.
[0085] Performance Testing
[0086] Esterification rate test: According to GB / T1668-2008 standard, the esterification rate of n-butyl acetate prepared in Examples 1-4 and Comparative Examples 1-5 is measured. Please reuse the catalyst 5 times, and measure its esterification rate after the first and fifth use respectively. The specific operation is: after the reaction is completed and cooled to room temperature, take the supernatant to determine the acid content in the mixed solution. Take 0.5mL of the mixed solution before and after the reaction and place it in a conical flask, and add 10mL of distilled water for dilution. After shaking thoroughly, add 2 drops of phenolphthalein reagent. Use a freshly prepared 0.1mol / L NaOH solution for titration, and record the volumes of NaOH solution consumed in the two titrations as V1 and V2 respectively. Calculate the esterification rate according to the following formula:
[0087] Esterification rate = (1-V2 / V1) × 100%;
[0088] The calculation results are shown in Table 1;
[0089] Table 1
[0090] Esterification rate / % (first time) Esterification rate / % (5th time) Example 1 99.3 89.8 Example 2 99.5 90.1 Example 3 99.5 90.0 Example 4 99.6 90.3 Comparative Example 1 88.3 75.9 Comparative Example 2 82.5 69.2 Comparative Example 3 87.1 74.8 Comparative Example 4 87.7 75.3 Comparative Example 5 88.6 76.2
[0091] From the test results in Table 1, it can be seen that compared with Comparative Examples 1-5, in Example 1-4, citric acid was not used to soak the molecular sieve in Comparative Example 1 of the present invention, and its pores were not increased, and the surface area of the active sites was less than , so the esterification rate was low; in Comparative Examples 2-4, aluminum zirconium coupling agent was not used, the firmness of the catalyst was poor, and friction during the repeated use of the catalyst caused the loss of active substances, so the esterification rate of the fifth and first repeated uses was quite different, and the fewer pores resulted in uneven distribution of internal active substances; in Comparative Example 5, amino acid was not used, and the content and stability of phosphotungstic acid in the composite catalyst decreased, resulting in a decrease in the esterification rate catalyzed by it. In summary, the composite catalyst prepared by the present invention has a higher esterification rate for the preparation of n-butyl acetate, can effectively reduce the occurrence of side reactions, and thus help to improve the purity of the n-butyl acetate product.
[0092] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technical personnel in this field can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.
Claims
1. A crude ester purification process for n-butyl acetate, It is characterized in that The purification process comprises the following steps: Adding glacial acetic acid and n-butanol to the composite catalyst and mixing evenly, heating and stirring, and then cooling with water to obtain n-butyl acetate; Wherein, the preparation method of the composite catalyst comprises the following steps: 1) adding molecular sieve particles to anhydrous ethanol and deionized water, stirring and mixing, adjusting the pH value, adding a silane coupling agent, heating and stirring, washing, filtering, and drying to obtain a preform; 2) mixing the preform, amino acid and deionized water, then adding phosphotungstic acid, heating and stirring, then placing in an oven for drying, and grinding to obtain a composite catalyst; The method for preparing the molecular sieve particles comprises the following steps: S1: Anhydrous ethanol, a template agent and deionized water are mixed and stirred, and ethyl orthosilicate is slowly added and stirred to obtain a mixture; S2: The mixture is transferred to a reactor equipped with a polytetrafluoroethylene liner for crystallization treatment, washed and centrifuged, the solid is taken, and citric acid solution is added for soaking. After removing the solution, aluminum zirconium coupling agent and anhydrous ethanol are added and stirred, and then placed in an oven for drying to constant weight and then heated and calcined to obtain molecular sieve particles.
2. A crude ester purification process for n-butyl acetate according to claim 1, Features: The mass ratio of the composite catalyst, glacial acetic acid and n-butanol is 0.02-0.04:1.3-1.4:3.2-3.5, and the heating and stirring is stirring at a temperature of 110-120° C. for 2-3 hours.
3. A crude ester purification process for n-butyl acetate according to claim 1, Features: In step 1), the mass ratio of molecular sieve particles, ethanol solution and silane coupling agent is 3-5:80-90:0.6-0.8; the pH value is adjusted to 4.0-4.2; the heating and stirring is stirred at 70-75°C for 6-8h; the washing is washed alternately with ethanol and deionized water for 3 times each; the drying is dried at 120-130°C to constant weight.
4. A crude ester purification process for n-butyl acetate according to claim 1, Features: The silane coupling agent is one or both of silane coupling agent KH550 and silane coupling agent KH560; the concentration of the ethanol solution is 50-60%.
5. A crude ester purification process for n-butyl acetate according to claim 1, Features: In step 2), the mass ratio of the preform, amino acid, deionized water and phosphotungstic acid is 10-12: 0.10-0.12: 30-40: 2-3.
6. A crude ester purification process for n-butyl acetate according to claim 1, Features: In step 2), the heating and stirring is to evaporate at a temperature of 70-75° C. until there is no water; and the drying is to dry at a temperature of 110° C. until constant weight.
7. A crude ester purification process for n-butyl acetate according to claim 1, Features: In step S1, the mass ratio of anhydrous ethanol, template, deionized water and tetraethyl orthosilicate is 10-12: 2.7-3:23-25:2-3; the template agent is a mixture of n-butylamine and tetrabutylammonium hydroxide in a mass ratio of 0.3:1; 8. A crude ester purification process for n-butyl acetate according to claim 1, Features: In step S2, the crystallization treatment is performed at 172-180°C for 2 days; the soaking time is 1 hour; the stirring and mixing is performed at 40-50°C for 30-45 minutes; the drying is performed at 110°C to constant weight; and the heating and calcination is performed at 310-350°C for 3-3.5 hours.
9. A crude ester purification process for n-butyl acetate according to claim 1, Features: In step S2, the mass ratio of the citric acid solution, the mixture, the aluminum zirconium coupling agent and anhydrous ethanol is 20:10-12:3-4:35-45; the aluminum zirconium coupling agent is aluminum zirconium coupling agent LD-139; and the concentration of the citric acid solution is 1.2 g / L.