A preparation method of tert-butyl (meth)acrylate

Abstract

The invention discloses a method for preparing tert-butyl (meth)acrylate, and belongs to the technical field of organic synthesis. The invention adds a catalyst, a polymerization inhibitor, (meth)acrylic acid and isobutylene into a reaction kettle for stirring and reacting to prepare tert-butyl (meth)acrylate. The catalyst is a composite oxide M1O x ‑M2O y , M1 in the catalyst is one or more of Fe, Nb, Sn, W, Ga, Re, Y, La, Ce, Nd, Sm, Er; M2O y The catalyst contains one or two of Al2O3 and SiO2, and the content of M1 in the catalyst is 0.1-10wt%. The process route of the invention is simple, the reaction conditions are mild, the catalyst and the raw material product are easy to separate, the invention is green and environmentally friendly, and pollution-free, and the esterification rate is improved, and the polymerization of the raw material and the product in the reaction process is effectively prevented, thereby reducing the production cost of tert-butyl acrylate.

Description

Technical Field

[0001] The invention belongs to the technical field of organic synthesis, and particularly relates to a method for preparing tert-butyl (meth)acrylate. Background Art

[0002] Tert-butyl acrylate is an extremely important chemical raw material and intermediate. Because of its unique and highly active polar molecules, unsaturated double bonds and carboxylic acid ester (-COOR) structure, it can be derived into many polymer formulas with good performance. The various tert-butyl acrylate polymers prepared have excellent properties such as strong adhesion, good transparency and clear film formation. Therefore, tert-butyl acrylate has excellent chemical and physical properties such as excellent light stability, weather resistance, water resistance, oil resistance, and chemical resistance.

[0003] In the industry, traditional esterification reactions are mostly synthesized by esterification of acrylic acid and tert-butyl alcohol under the catalysis of concentrated sulfuric acid. During the reaction, due to the large steric hindrance of tert-butyl alcohol, the elimination reaction is more inclined to the two competitive reactions of esterification and elimination, and the esterification rate is low. This reaction has many side reactions, the product color is dark, the post-processing process is complicated, the equipment is severely corroded, and the wastewater discharge is large.

[0004] The acid-ene addition method is a method for producing tert-butyl acrylate products that is widely used. It is a typical green chemical atom-economic process. It replaces tert-butyl alcohol with abundant and cheap isobutylene, which not only improves the reaction conversion rate but also reduces the production cost. However, there are still a series of technical problems in the prior art, such as low esterification rate, low reaction selectivity, and polymerization of raw materials and products. Therefore, how to improve the esterification rate of tert-butyl acrylate and effectively prevent the polymerization of raw materials and products during the reaction process is an important problem that needs to be solved urgently. Summary of the invention

[0005] In view of this, the purpose of the present invention is to provide a method for preparing tert-butyl (meth)acrylate. The method for preparing tert-butyl (meth)acrylate by using a composite oxide as a catalyst and a special catalytic system composed of multiple polymerization inhibitors and oxygen-containing nitrogen to catalyze (meth)acrylic acid and isobutylene to synthesize tert-butyl (meth)acrylate significantly improves the esterification rate of tert-butyl (meth)acrylate, and effectively prevents uneven mixing of raw materials during the reaction and solves the polymerization problem of raw materials and products.

[0006] To achieve the purpose of the present invention, the present invention provides the following technical solutions:

[0007] The present invention provides a method for preparing tert-butyl (meth)acrylate. The method comprises adding a catalyst, a polymerization inhibitor, (meth)acrylic acid and isobutylene into a reaction kettle and stirring the mixture to react so as to prepare tert-butyl (meth)acrylate. The catalyst is a composite oxide M1O x -M2O y .

[0008] Furthermore, M1 in the catalyst is one or more of Fe, Nb, Sn, W, Ga, Re, Y, La, Ce, Nd, Sm, and Er; M2O y For Al 2 O 3 、SiO 2 One or both.

[0009] Furthermore, the content of M1 in the catalyst is 0.1-10wt%.

[0010] Furthermore, the inhibitor is used in combination with air, wherein the inhibitor is a combination of tert-butyl alcohol, phenothiazine, p-hydroxyanisole and tert-butylcatechol, with a mass ratio of 10-15:4-6:2-4:4-6.

[0011] Furthermore, the mass ratio of tert-butyl alcohol, phenothiazine, p-hydroxyanisole and tert-butylcatechol is 12:5:3:5.

[0012] Further, the reaction temperature is 30-60°C, the air pressure is 0.1-5.0MPa, the reaction time is 2-10h, and the stirring rate is 500-1500rpm;

[0013] Furthermore, the molar ratio of (meth)acrylic acid to isobutylene is 1:5-5:1.

[0014] Furthermore, the polymerization inhibitor is 0.01-1% of the mass of (meth)acrylic acid.

[0015] Furthermore, the mass of the catalyst is 5-20% of the mass of (meth)acrylic acid.

[0016] Furthermore, the (meth)acrylic acid includes acrylic acid and methacrylic acid; and the tert-butyl (meth)acrylate includes tert-butyl acrylate and tert-butyl methacrylate.

[0017] Furthermore, the catalyst is prepared by a hydrothermal method, and the specific process is as follows:

[0018] (1) dissolving the soluble salt of M1 and the soluble salt of M2 in water according to the required mass ratio, and rapidly stirring for 2-6 hours to obtain solution A after complete dissolution;

[0019] (2) slowly adding a certain amount of precipitant to solution A to obtain a solution;

[0020] (3) Continue to slowly add a certain amount of ammonia water until the pH of the solution is 7-10.5, and stir rapidly for 1-5 hours to obtain solution B;

[0021] (4) Transferring solution B to a hydrothermal reactor with an inner liner and crystallizing at 70-180° C. for 6-72 h;

[0022] (5) washing the product obtained in step (4) until it is neutral, and vacuum drying it at 50-80° C. for 24-48 hours to obtain a composite oxide precursor;

[0023] (6) calcining the composite oxide precursor at 400-900°C in an inert atmosphere for 2-8 hours to obtain the composite oxide M1O x -M2O y catalyst.

[0024] Further, the precipitant in step (2) is NH 4 HCO 3 NH 4 ) 2 CO 3 、Na 2 CO 3 Or one or more of urea.

[0025] Furthermore, in step (4), the crystallization temperature is 80-140° C., and the crystallization time is 12-36 hours.

[0026] Furthermore, in step (6), the calcination temperature is 500-600° C., and the heating rate is 1-10° C. / min.

[0027] Furthermore, the inert atmosphere in step (6) includes nitrogen, helium and argon.

[0028] The beneficial effects of the present invention compared with the prior art are as follows:

[0029] 1. The present invention aims at a series of technical problems in the prior art, such as low activity, rapid deactivation and low reaction selectivity of the catalyst used for producing tert-butyl acrylate by the acid-ene addition method. The present invention provides a preparation method for synthesizing tert-butyl acrylate by catalyzing acrylic acid and isobutylene with a composite oxide as a catalyst and a special catalytic system composed of a plurality of polymerization inhibitors and oxygen-containing nitrogen. The method can significantly improve the esterification rate of tert-butyl acrylate, effectively prevent uneven mixing of raw materials during the reaction, and solve the polymerization problem of raw materials and products.

[0030] 2. The catalyst of the present invention is simple to prepare and has good repeatability, and the reaction esterification rate is highly selective;

[0031] 3. The preparation method of the present invention is simple and environmentally friendly, does not generate waste acid and waste water, and does not require waste acid and waste water treatment. It is a true atom-economic reaction, which reduces production costs. DETAILED DESCRIPTION

[0032] The present invention is described in detail below with reference to the embodiments, but the embodiments of the present invention are not limited thereto. Obviously, the embodiments described below are only partial embodiments of the present invention. For those skilled in the art, other similar embodiments obtained without creative labor all fall within the protection scope of the present invention.

[0033] Example 1

[0034] 39.0 g Al(NO 3 ) 3 9H 2 O and 1.64g La(NO 3 ) 3 6H 2 O was added to 200 ml of deionized water and stirred rapidly for 1 h until it was completely dissolved. Then 19.0 g of NH 4 HCO 3 Then, continue to slowly add a certain amount of ammonia water until the pH of the solution is 10, and stir rapidly for 2 hours;

[0035] The obtained solution was transferred into a 200 ml stainless steel high-pressure hydrothermal autoclave, sealed and placed in a 120°C oven. After reacting for 24 h, the autoclave was naturally cooled to room temperature. The obtained solid was centrifugally washed with deionized water several times until neutral. The solid was then placed in a vacuum dryer at 80°C for 24 h. After drying, the solid was placed in a quartz tube furnace and heated at N 2 The calcination was carried out at a temperature of 550°C for 6 hours, with a heating rate of 5°C / min. After the calcination, the particles were properly ground to obtain the catalyst La 2 O 3 -Al 2 O 3 .

[0036] Acrylic acid, La 2 O 3 -Al 2 O 3 A catalyst, an inhibitor and liquid isobutylene are put into a reaction kettle, and the reaction is stirred for 4 hours at a temperature of 35° C. and an air pressure of 1.0 MPa, with a stirring rate of 800 rpm to synthesize tert-butyl acrylate; wherein the mass ratio of acrylic acid, the inhibitor and isobutylene is 10:0.01:5.5, the mass of the catalyst is 10% of the mass of acrylic acid, and the inhibitor is a mixture of tert-butyl alcohol, phenothiazine, p-hydroxyanisole and tert-butyl catechol, and the mass ratio is 12:5:3:5.

[0037] Example 2

[0038] 39.0 g Al(NO 3 ) 39H 2 O and 3.80g Fe(NO 3 ) 3 6H 2 O was added to 200 ml of deionized water and stirred rapidly for 1 h until it was completely dissolved. Then 16.6 g of NH 4 HCO 3 Then, continue to slowly add a certain amount of ammonia water until the pH of the solution is 10, and stir rapidly for 2 hours;

[0039] The obtained solution was transferred into a 200 ml stainless steel high pressure hydrothermal autoclave, sealed and placed in a 120°C oven. After reacting for 24 hours, the autoclave was naturally cooled to room temperature, and the obtained solid was centrifugally washed with deionized water several times until neutral, and then the solid was placed in a vacuum dryer at 80°C for 24 hours. After drying, the solid was placed in a quartz tube furnace and heated at N 2 The calcination was carried out at a temperature of 550°C for 6 hours, with a heating rate of 5°C / min. After the calcination, the particles were properly ground to obtain the catalyst Fe 2 O 3 -Al 2 O 3 .

[0040] Acrylic acid, Fe 2 O 3 -Al 2 O 3 A catalyst, an inhibitor and liquid isobutylene are put into a reaction kettle, and the reaction is stirred for 4 hours at a temperature of 35° C. and an air pressure of 1.0 MPa, with a stirring rate of 800 rpm to synthesize tert-butyl acrylate; wherein the mass ratio of acrylic acid, the inhibitor and isobutylene is 10:0.01:5.5, the mass of the catalyst is 10% of the mass of acrylic acid, and the inhibitor is a mixture of tert-butyl alcohol, phenothiazine, p-hydroxyanisole and tert-butyl catechol, and the mass ratio is 12:5:3:5.

[0041] Example 3

[0042] 39.0 g Al(NO 3 ) 3 9H 2 O and 1.60g Nd(NO 3 ) 3 6H 2 O was added to 200 ml of deionized water and stirred rapidly for 1 h to completely dissolve. Then 15.81 g of NH 4 HCO 3 Then, continue to slowly add a certain amount of ammonia water until the pH of the solution is 10, and stir rapidly for 2 hours;

[0043] The obtained solution was transferred into a 200 ml stainless steel high pressure hydrothermal autoclave, sealed and placed in a 120°C oven. After reacting for 24 h, the autoclave was naturally cooled to room temperature. The obtained solid was centrifugally washed with deionized water several times until neutral. The solid was then placed in a vacuum dryer at 80°C for 24 h. After drying, the solid was placed in a quartz tube furnace and heated under N 2 The calcination was carried out at a temperature of 550°C for 6 hours, with a heating rate of 5°C / min. After the calcination, the particles were properly ground to obtain the catalyst Nd 2 O 3 -Al 2 O 3 .

[0044] Acrylic acid, Nd 2 O 3 -Al 2 O 3 A catalyst, an inhibitor and liquid isobutylene are put into a reaction kettle, and the reaction is stirred for 4 hours at a temperature of 35° C. and an air pressure of 1.0 MPa, with a stirring rate of 800 rpm to synthesize tert-butyl acrylate; wherein the mass ratio of acrylic acid, the inhibitor and isobutylene is 10:0.01:5.5, the mass of the catalyst is 10% of the mass of acrylic acid, and the inhibitor is a mixture of tert-butyl alcohol, phenothiazine, p-hydroxyanisole and tert-butyl catechol, and the mass ratio is 12:5:3:5.

[0045] Example 4

[0046] 39.0 g Al(NO 3 ) 3 9H 2 O and 1.56 g Sm(NO 3 ) 3 6H 2 O was added to 200 ml of deionized water and stirred rapidly for 1 h to completely dissolve. Then 15.80 g of NH 4 HCO 3 Then, continue to slowly add a certain amount of ammonia water until the pH of the solution is 10, and stir rapidly for 2 hours;

[0047] The obtained solution was transferred into a 200 ml stainless steel high pressure hydrothermal autoclave, sealed and placed in a 120°C oven. After reacting for 24 hours, the autoclave was naturally cooled to room temperature, and the obtained solid was centrifugally washed with deionized water several times until neutral, and then the solid was placed in a vacuum dryer at 80°C for 24 hours. After drying, the solid was placed in a quartz tube furnace and heated at N 2 The calcination was carried out at 550°C for 6 hours with a heating rate of 5°C / min. After the calcination, the particles were ground appropriately to obtain the catalyst Sm 2 O3 -Al 2 O 3 .

[0048] Acrylic acid, Sm 2 O 3 -Al 2 O 3 A catalyst, an inhibitor and liquid isobutylene are put into a reaction kettle, and the reaction is stirred for 4 hours at a temperature of 35° C. and an air pressure of 1.0 MPa, with a stirring rate of 800 rpm to synthesize tert-butyl acrylate; wherein the mass ratio of acrylic acid, the inhibitor and isobutylene is 10:0.01:5.5, the mass of the catalyst is 10% of the mass of acrylic acid, and the inhibitor is a mixture of tert-butyl alcohol, phenothiazine, p-hydroxyanisole and tert-butyl catechol, and the mass ratio is 12:5:3:5.

[0049] Example 5

[0050] 39.0 g Al(NO 3 ) 3 9H 2 O, 1.56 g Sm(NO 3 ) 3 6H 2 O and 1.60g Nd(NO 3 ) 3 6H 2 O was added to 200 ml of deionized water and stirred rapidly for 1 h to completely dissolve. Then 15.81 g of NH 4 HCO 3 Then, a certain amount of ammonia water was slowly added until the pH of the solution was 10, and the mixture was stirred rapidly for 2 h.

[0051] The obtained solution was transferred into a 200 ml stainless steel high pressure hydrothermal autoclave, sealed and placed in a 120°C oven. After reacting for 24 hours, the autoclave was naturally cooled to room temperature, and the obtained solid was centrifugally washed with deionized water several times until neutral, and then the solid was placed in a vacuum dryer at 80°C for 24 hours. After drying, the solid was placed in a quartz tube furnace and heated at N 2 The calcination was carried out at 550°C for 6 hours with a heating rate of 5°C / min. After the calcination, the particles were ground appropriately to obtain the catalyst Sm 2 O 3 -Nd 2 O 3 -Al 2 O 3 .

[0052] Acrylic acid, Sm 2 O 3 -Nd 2O 3 -Al 2 O 3 A catalyst, an inhibitor and liquid isobutylene are put into a reaction kettle, and the reaction is stirred for 4 hours at a temperature of 35° C. and an air pressure of 1.0 MPa, with a stirring rate of 800 rpm to synthesize tert-butyl acrylate; wherein the mass ratio of acrylic acid, the inhibitor and isobutylene is 10:0.01:5.5, the mass of the catalyst is 10% of the mass of acrylic acid, and the inhibitor is a mixture of tert-butyl alcohol, phenothiazine, p-hydroxyanisole and tert-butyl catechol, and the mass ratio is 12:5:3:5.

[0053] Example 6

[0054] 17.36 g of ethyl orthosilicate and 1.60 g of Nd(NO 3 ) 3 6H 2 O was added to 200 ml of deionized water, stirred rapidly at 40 °C for complete hydrolysis, and then 15.81 g of NH 4 HCO 3 Then, continue to slowly add a certain amount of ammonia water until the pH of the solution is 10, and stir rapidly for 2 hours;

[0055] The obtained solution was transferred into a 200 ml stainless steel high pressure hydrothermal autoclave, sealed and placed in a 120°C oven. After reacting for 24 hours, the autoclave was naturally cooled to room temperature, and the obtained solid was centrifugally washed with deionized water several times until neutral, and then the solid was placed in a vacuum dryer at 80°C for 24 hours. After drying, the solid was placed in a quartz tube furnace and heated at N 2 The calcination was carried out at a temperature of 550°C for 6 hours, with a heating rate of 5°C / min. After the calcination, the particles were properly ground to obtain the catalyst Nd 2 O 3 -SiO 2 .

[0056] Acrylic acid, Nd 2 O 3 -SiO 2 A catalyst, an inhibitor and liquid isobutylene are put into a reaction kettle, and the reaction is stirred for 4 hours at a temperature of 35° C. and an air pressure of 1.0 MPa, with a stirring rate of 800 rpm to synthesize tert-butyl acrylate; wherein the mass ratio of acrylic acid, the inhibitor and isobutylene is 10:0.01:5.5, the mass of the catalyst is 10% of the mass of acrylic acid, and the inhibitor is a mixture of tert-butyl alcohol, phenothiazine, p-hydroxyanisole and tert-butyl catechol, and the mass ratio is 12:5:3:5.

[0057] Example 7

[0058] 16.67 g of 30% silica sol and 1.60 g of Nd(NO 3 ) 3 6H 2 O was added to 200 ml of deionized water and stirred rapidly for 1 h to completely dissolve. Then 15.81 g of NH 4 HCO 3 Then, a certain amount of ammonia water was slowly added until the pH of the solution was 10, and the mixture was stirred rapidly for 2 h.

[0059] The obtained solution was transferred into a 200 ml stainless steel high pressure hydrothermal autoclave, sealed and placed in a 120°C oven. After reacting for 24 hours, the autoclave was naturally cooled to room temperature, and the obtained solid was centrifugally washed with deionized water several times until neutral, and then the solid was placed in a vacuum dryer at 80°C for 24 hours. After drying, the solid was placed in a quartz tube furnace and heated at N 2 The calcination was carried out at a temperature of 550°C for 6 hours, with a heating rate of 5°C / min. After the calcination, the particles were properly ground to obtain the catalyst Nd 2 O 3 -SiO 2 (s).

[0060] Acrylic acid, Nd 2 O 3 -SiO 2 (s) A catalyst, an inhibitor and liquid isobutylene are placed in a reaction kettle, and the reaction is stirred for 4 hours at a temperature of 35° C. and an air pressure of 1.0 MPa, with a stirring rate of 800 rpm to synthesize tert-butyl acrylate; wherein the mass molar ratio of acrylic acid, inhibitor and isobutylene is 10:0.01:5.5, the mass of the catalyst is 10% of the mass of acrylic acid, and the inhibitor is a mixture of tert-butyl alcohol, phenothiazine, p-hydroxyanisole and tert-butylcatechol in a mass ratio of 12:5:3:5.

[0061] Example 8

[0062] 8.68 g of ethyl orthosilicate, 19.5 g of Al(NO 3 ) 3 9H 2 O and 1.60g Nd(NO 3 ) 3 6H 2 O was added to 200 ml of deionized water and after complete hydrolysis under rapid stirring, 15.81 g of NH 4 HCO 3 Then, a certain amount of ammonia water was slowly added until the pH of the solution was 10, and the mixture was stirred rapidly for 2 h.

[0063] The obtained solution was transferred into a 200 ml stainless steel high pressure hydrothermal autoclave, sealed and placed in a 120°C oven. After reacting for 24 hours, the autoclave was naturally cooled to room temperature, and the obtained solid was centrifugally washed with deionized water several times until neutral, and then the solid was placed in a vacuum dryer at 80°C for 24 hours. After drying, the solid was placed in a quartz tube furnace and heated at N 2 The calcination was carried out at a temperature of 550°C for 6 hours, with a heating rate of 5°C / min. After the calcination, the particles were properly ground to obtain the catalyst Nd 2 O 3 -SiO 2 -Al 2 O 3 .

[0064] Acrylic acid, Nd 2 O 3 -SiO 2 -Al 2 O 3 A catalyst, an inhibitor and liquid isobutylene are put into a reaction kettle, and the reaction is stirred for 4 hours at a temperature of 35° C. and an air pressure of 1.0 MPa, with a stirring rate of 800 rpm to synthesize tert-butyl acrylate; wherein the mass ratio of acrylic acid, the inhibitor and isobutylene is 10:0.01:5.5, the mass of the catalyst is 10% of the mass of acrylic acid, and the inhibitor is a mixture of tert-butyl alcohol, phenothiazine, p-hydroxyanisole and tert-butyl catechol, and the mass ratio is 12:5:3:5.

[0065] Example 9

[0066] 39.0 g Al(NO 3 ) 3 9H 2 O, 1.56 g Sm(NO 3 ) 3 6H 2 O and 1.60g Nd(NO 3 ) 3 6H 2 O was added to 200 ml of deionized water and stirred rapidly for 1 h to completely dissolve. Then 15.81 g of NH 4 HCO 3 Then, a certain amount of ammonia water was slowly added until the pH of the solution was 10, and the mixture was stirred rapidly for 2 h.

[0067] The obtained solution was transferred into a 200 ml stainless steel high pressure hydrothermal autoclave, sealed and placed in a 120°C oven. After reacting for 24 hours, the autoclave was naturally cooled to room temperature, and the obtained solid was centrifugally washed with deionized water several times until neutral, and then the solid was placed in a vacuum dryer at 80°C for 24 hours. After drying, the solid was placed in a quartz tube furnace and heated at N2 The calcination was carried out at 550°C for 6 hours with a heating rate of 5°C / min. After the calcination, the particles were ground appropriately to obtain the catalyst Sm 2 O 3 -Nd 2 O 3 -Al 2 O 3 .

[0068] Acrylic acid, Sm 2 O 3 -Nd 2 O 3 -Al 2 O 3 Catalyst, inhibitor and liquid isobutylene were put into a reactor, stirred for 4 hours at a temperature of 35°C and an air pressure of 1.0 MPa, and the stirring rate was 800 rpm to synthesize tert-butyl acrylate; wherein the mass ratio of acrylic acid, inhibitor and isobutylene was 10:0.01:5.5, the mass of the catalyst was 10% of the mass of acrylic acid, and the inhibitor was a mixture of tert-butyl alcohol, phenothiazine, p-hydroxyanisole and tert-butyl catechol, and the mass ratio was 12:5:3:5. The catalyst was recycled for six times, and the results are shown in Table 1.

[0069] Comparative Example 1

[0070] 39.0 g Al(NO 3 ) 3 9H 2 O was added to 200 ml of deionized water and stirred rapidly for 1 h until it was completely dissolved. Then 19.0 g of NH 4 HCO 3 Then, continue to slowly add a certain amount of ammonia water until the pH of the solution is 10, and stir rapidly for 2 hours;

[0071] The obtained solution was transferred into a 200 ml stainless steel high-pressure hydrothermal autoclave, sealed and placed in a 120°C oven; after reacting for 24 hours, the autoclave was naturally cooled to room temperature, the obtained solid was centrifugally washed with deionized water several times until neutral, and then the solid was placed in a vacuum dryer at 80°C for 24 hours; after drying, the solid was placed in a quartz tube furnace and heated under N 2 The calcination was carried out at a temperature of 550°C for 6 hours, with a heating rate of 5°C / min. After the calcination, the particles were properly ground to obtain the catalyst Al 2 O 3 .

[0072] Acrylic acid, Al 2 O 3A catalyst, an inhibitor and liquid isobutylene are put into a reaction kettle, and the reaction is stirred for 4 hours at a temperature of 35° C. and an air pressure of 1.0 MPa, with a stirring rate of 800 rpm to synthesize tert-butyl acrylate; wherein the mass ratio of acrylic acid, the inhibitor and isobutylene is 10:0.01:5.5, the mass of the catalyst is 10% of the mass of acrylic acid, and the inhibitor is a mixture of tert-butyl alcohol, phenothiazine, p-hydroxyanisole and tert-butyl catechol, and the mass ratio is 12:5:3:5.

[0073] Comparative Example 2

[0074] 16.67 g of 30% silica sol was added to 200 ml of deionized water. After rapid stirring for 1 h until completely dissolved, 15.81 g of NH 4 HCO 3 Then, a certain amount of ammonia water was slowly added until the pH of the solution was 10, and the mixture was stirred rapidly for 2 h.

[0075] The obtained solution was transferred into a 200 ml stainless steel high pressure hydrothermal autoclave, sealed and placed in a 120°C oven. After reacting for 24 hours, the autoclave was naturally cooled to room temperature, and the obtained solid was centrifugally washed with deionized water several times until neutral, and then the solid was placed in a vacuum dryer at 80°C for 24 hours. After drying, the solid was placed in a quartz tube furnace and heated at N 2 The calcination was carried out at a temperature of 550°C for 6 hours, with a heating rate of 5°C / min. After the calcination, the particles were properly ground to obtain the catalyst SiO 2 (s).

[0076] Acrylic acid, SiO 2 (s) A catalyst, an inhibitor and liquid isobutylene are placed in a reaction kettle, and the reaction is stirred for 4 hours at a temperature of 35° C. and an air pressure of 1.0 MPa, with a stirring rate of 800 rpm to synthesize tert-butyl acrylate; wherein the mass ratio of acrylic acid, inhibitor and isobutylene is 10:0.01:5.5, the mass of the catalyst is 10% of the mass of acrylic acid, and the inhibitor is a mixture of tert-butyl alcohol, phenothiazine, p-hydroxyanisole and tert-butylcatechol in a mass ratio of 12:5:3:5.

[0077] Comparative Example 3

[0078] 6.67 g Nd(NO 3 ) 3 6H 2 O was added to 200 ml of deionized water and after rapid stirring for 1 h to completely dissolve, 2.45 g of NH 4 HCO 3Then, a certain amount of ammonia water was slowly added until the pH of the solution was 10, and the mixture was stirred rapidly for 2 h.

[0079] The obtained solution was transferred into a 200 ml stainless steel high pressure hydrothermal autoclave, sealed and placed in a 120°C oven. After reacting for 24 hours, the autoclave was naturally cooled to room temperature, and the obtained solid was centrifugally washed with deionized water several times until neutral, and then the solid was placed in a vacuum dryer at 80°C for 24 hours. After drying, the solid was placed in a quartz tube furnace and heated at N 2 The calcination was carried out at a temperature of 550°C for 6 hours, with a heating rate of 5°C / min. After the calcination, the particles were properly ground to obtain the catalyst Nd 2 O 3 .

[0080] Acrylic acid, Nd 2 O 3 A catalyst, an inhibitor and liquid isobutylene are put into a reaction kettle, and the reaction is stirred for 4 hours at a temperature of 35° C. and an air pressure of 1.0 MPa, with a stirring rate of 800 rpm to synthesize tert-butyl acrylate; wherein the mass ratio of acrylic acid, the inhibitor and isobutylene is 10:0.01:5.5, the mass of the catalyst is 10% of the mass of acrylic acid, and the inhibitor is a mixture of tert-butyl alcohol, phenothiazine, p-hydroxyanisole and tert-butyl catechol, and the mass ratio is 12:5:3:5.

[0081] Comparative Example 4

[0082] With p-toluenesulfonic acid as a catalyst, acrylic acid, a catalyst, an inhibitor and liquid isobutylene are put into a reactor, and the reaction is stirred for 4 hours at a temperature of 35° C. and an air pressure of 1.0 MPa, with a stirring rate of 800 rpm to synthesize tert-butyl acrylate; wherein the feeding molar ratio of acrylic acid, the inhibitor and the isobutylene is 1.0:0.08:1.0, the mass of the catalyst 1.0 g is 10% of the mass of the acrylic acid, and the inhibitor is a mixture of tert-butyl alcohol, phenothiazine, p-hydroxyanisole and tert-butyl catechol, and the mass ratio is 12:5:3:5.

[0083] Comparative Example 5

[0084] With an acidic cationic resin as a catalyst, acrylic acid, a catalyst, an inhibitor and liquid isobutylene are put into a reactor, and the reaction is stirred for 4 hours at a temperature of 35° C. and an air pressure of 1.0 MPa, with a stirring rate of 800 rpm to synthesize tert-butyl acrylate; wherein the mass ratio of acrylic acid, inhibitor and isobutylene is 10:0.01:5.5, the mass of 1.0 g of the catalyst is 10% of the mass of acrylic acid, and the inhibitor is a mixture of tert-butyl alcohol, phenothiazine, p-hydroxyanisole and tert-butyl catechol, and the mass ratio is 12:5:3:5.

[0085] Comparative Example 6

[0086] 39.0 g Al(NO 3 ) 3 9H 2 O, 1.56 g Sm(NO 3 ) 3 6H 2 O and 1.60g Nd(NO 3 ) 3 6H 2 O was added to 200 ml of deionized water and stirred rapidly for 1 h to completely dissolve. Then 15.81 g of NH 4 HCO 3 Then, a certain amount of ammonia water was slowly added until the pH of the solution was 10, and the mixture was stirred rapidly for 2 h.

[0087] The obtained solution was transferred into a 200 ml stainless steel high pressure hydrothermal autoclave, sealed and placed in a 120°C oven. After reacting for 24 hours, the autoclave was naturally cooled to room temperature, and the obtained solid was centrifugally washed with deionized water several times until neutral, and then the solid was placed in a vacuum dryer at 80°C for 24 hours. After drying, the solid was placed in a quartz tube furnace and heated at N 2 The calcination was carried out at 550°C for 6 hours with a heating rate of 5°C / min. After the calcination, the particles were ground appropriately to obtain the catalyst Sm 2 O 3 -Nd 2 O 3 -Al 2 O 3 .

[0088] Acrylic acid, Sm 2 O 3 -Nd 2 O 3 -Al 2 O 3 The catalyst and liquid isobutylene were put into a reactor, and the reaction was stirred for 4 hours at a temperature of 35° C. and an air pressure of 1.0 MPa, with a stirring rate of 800 rpm to synthesize tert-butyl acrylate; wherein the mass ratio of acrylic acid to isobutylene was 10:5.5, and the mass of the catalyst was 10% of the mass of acrylic acid.

[0089] In this example, tert-butyl acrylate prepared in Examples 1-9 and Comparative Examples 1-6 was tested. The test standard adopted conventional experiments and regulations in the field to determine the esterification rate. The specific results are shown in Table 1, where:

[0090] When the olefin is in excess, the esterification rate is calculated according to formula (1):

[0091] Esterification rate = (1-acid value of the system after reaction / acid value of the system before reaction)*100% (1);

[0092] When the acid is in excess, the esterification rate is calculated based on the molar ratio of the olefinic acid, as shown in formula (2):

[0093] Esterification rate = [esterification rate in formula (1) / olefinic acid molar ratio]*100% (2).

[0094] The product selectivity was calculated based on the ratio of the chromatographic peak areas. The results are shown in Table 1.

[0095] Table 1. Esterification rate and tert-butyl acrylate selectivity of Examples 1-9 and Comparative Examples 1-6

[0096] Implementation catalyst Esterification rate% Tert-butyl acrylate selectivity % Example 1 <![CDATA[La 2 A 3 Al 2 A 3 ]]> 77.8 92.4 Example 2 <![CDATA[Fe 2 A 3 Al 2 A 3 ]]> 63.6 94.6 Example 3 <![CDATA[Nd 2 A 3 Al 2 A 3 ]]> 85.0 97.7 Example 4 <![CDATA[Sm 2 A 3 Al 2 A 3 ]]> 84.3 98.3 Example 5 <![CDATA[Sm 2 Oh 3 -Nd 2 Oh 3 -Al 2 Oh 3 ]]> 92.6 97.2 Example 6 <![CDATA[Nd 2 Oh 3 -SiO 2 ]]> 80.1 93.5 Example 7 <![CDATA[Nd 2 O 3 -SiO 2 (s)]]> 73.2 95.4 Example 8 <![CDATA[Nd 2 The 3 -SiO 2 -Al 2 The 3 ]]> 86.5 96.8 Example 9 <![CDATA[Sm 2 Oh 3 -Nd 2 Oh 3 -Al 2 Oh 3 ]]> 93.2 97.9 Comparative Example 1 <![CDATA[Al 2 THE 3 ]]> 27.4 94.3 Comparative Example 2 <![CDATA[SiO 2 (s)]]> 35.8 98.6 Comparative Example 3 <![CDATA[Nd 2 THE 3 ]]> 42.9 95.5 Comparative Example 4 p-Toluenesulfonic acid 82.6 94.8 Comparative Example 5 Acidic cationic resin 86.5 95.4 Comparative Example 6 <![CDATA[Sm 2 Oh 3 -Nd 2 Oh 3 -Al 2 Oh 3 ]]> 54.7 83.2

[0097] From the results in Table 1, it can be seen that, compared with the comparative example, the preparation method of the present invention significantly improves the esterification rate of the esterification reaction, is more environmentally friendly and economical, and effectively prevents the polymerization of raw materials and products during the reaction process to improve the selectivity of the product.

[0098] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing tert-butyl (meth)acrylate, characterized in that: The catalyst, polymerization inhibitor, (meth) acrylic acid and isobutylene are added into a reaction kettle and stirred for reaction to prepare tert-butyl (meth)acrylate. The catalyst is a composite oxide M1O x -M2O y ; M1 in the catalyst is one or more of Fe, Nb, Sn, W, Ga, Re, Y, La, Ce, Nd, Sm, and Er; M2O y It is one or two of Al2O3 and SiO2; the content of M1 in the catalyst is 0.1-30wt%; The inhibitor is used in combination with air, wherein the inhibitor is a combination of tert-butyl alcohol, phenothiazine, p-hydroxyanisole and tert-butylcatechol, with a mass ratio of 10-15:4-6:2-4:4-6; The reaction temperature is 30-60°C, the air pressure is 0.1-5.0MPa, the reaction time is 2-10h, and the stirring rate is 500-1500rpm; The catalyst is prepared by hydrothermal method, and the specific process is as follows: (1) dissolving the soluble salt of M1 and the soluble salt of M2 in water in a desired mass ratio, and obtaining solution A after the soluble salts are completely dissolved; (2) slowly adding a certain amount of precipitant to solution A to obtain a solution; (3) Continue to slowly add a certain amount of ammonia water until the pH of the solution is 7-10.5, and stir rapidly for 1-5 hours to obtain solution B; (4) Transferring solution B to a hydrothermal reactor with an inner liner and crystallizing at 70-180° C. for 6-72 h; (5) washing the product obtained in step (4) until it is neutral, and vacuum drying it at 50-80° C. for 24-48 hours to obtain a composite oxide precursor; (6) calcining the composite oxide precursor at 400-900°C in an inert atmosphere for 2-8 hours to obtain the composite oxide M1O x -M2O y catalyst.

2. The preparation method according to claim 1, characterized in that: The molar ratio of (meth)acrylic acid to isobutylene is 1:5-5:1; the inhibitor is 0.01-1% of the mass of (meth)acrylic acid; and the mass of the catalyst is 5-20% of the mass of (meth)acrylic acid.

3. The preparation method according to claim 1, characterized in that: The (meth)acrylic acid includes acrylic acid and methacrylic acid; and the tert-butyl (meth)acrylate includes tert-butyl acrylate and tert-butyl methacrylate.

4. The preparation method according to claim 1, characterized in that: The precipitant in step (2) is one or more of NH4HCO3, (NH4)2CO3, Na2CO3 or urea.

5. The preparation method according to claim 1, characterized in that: In step (4), the crystallization temperature is 80-140° C., and the crystallization time is 12-36 hours.

6. The preparation method according to claim 1, characterized in that: In step (6), the calcination temperature is 500-600° C., and the heating rate is 1-10° C. / min; the inert atmosphere includes nitrogen, helium and argon.