Catalyst, preparation method and application thereof, and synthetic method of dimethylaminoethyl acrylate

Abstract

The invention relates to the technical field of organic synthesis, in particular to a catalyst, a preparation method and application thereof and a synthetic method of dimethylaminoethyl acrylate. According to the method disclosed by the invention, acrylic acid and N, N-dimethylethanolamine are used as raw materials, and the HZSM-5 molecular sieve loaded calcium-zinc-tin composite catalyst CaCl2-ZnCl2-SnCl4-HZSM-5 is used as a catalyst, so that dimethylaminoethyl acrylate can be efficiently synthesized. According to the preparation method, the HZSM-5 molecular sieve loaded calcium-zinc-tin composite catalyst CaCl2-ZnCl2-SnCl4-HZSM-5 is used as the catalyst, so that not only can the esterification reaction be efficiently catalyzed, but also the yield and the purity of the dimethylaminoethyl acrylate are high, and the generation of a large number of by-products is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of organic synthesis, and particularly relates to a catalyst, a preparation method and an application thereof, and a synthesis method of dimethylaminoethyl acrylate. Background Art

[0002] Disclosing the information of this background art section is only intended to enhance the overall understanding of the present invention, and is not necessarily regarded as an admission or an implication in any form that this information constitutes the prior art already known to those of ordinary skill in the art.

[0003] Dimethylaminoethyl acrylate (abbreviated as DA) is an important methacrylate. Since its molecule contains active groups such as vinyl and tertiary amine groups, it can be used to synthesize high molecular compounds with active amino or quaternary ammonium groups through polymerization reactions, and is widely used in the fields of water treatment, papermaking, coatings, medicine and healthcare, oilfield chemicals, adhesives, fiber auxiliaries, and plastic and rubber modification.

[0004] At present, there are mainly five production methods for dimethylaminoethyl acrylate, namely esterification method, transesterification method, high-temperature pyrolysis method, chloropropyl acyl chloride method, and acryloyl chloride method. Among them, the transesterification method is the main method currently in production, and the transesterification reaction is carried out between methyl acrylate and dimethylaminoethanol; however, the transesterification method has the following disadvantages: since the raw material methyl acrylate and the by-product methanol are azeotropes, a large excess of methyl acrylate is required to improve the reaction conversion rate; in order to improve the yield, the azeotrope of methanol and methyl acrylate is taken out of the system, so that the equilibrium shifts towards the direction of synthesizing dimethylaminoethyl acrylate; the azeotrope of methyl acrylate and methanol needs to be separated again through methods such as extractive distillation, resulting in high process energy consumption and large equipment investment. The high-temperature pyrolysis method can overcome the disadvantages of difficult separation of the azeotrope of methanol and methyl acrylate and low product purity in the transesterification method, but there are problems such as complex process and difficulty in industrialization. The by-products hydrogen chloride generated by the chloropropyl acyl chloride method and the acryloyl chloride method need to be absorbed by alkaline substances, which is likely to cause equipment corrosion and environmental pollution, and the acyl chloride is toxic, making it difficult to industrialize. The esterification method is directly dehydrated and esterified from acrylic acid and dimethylaminoethanol in the presence of the dehydrating agent concentrated sulfuric acid, and the overall process flow is simple and suitable for industrialization.

[0005] However, the efficiency of directly dehydrating and esterifying to synthesize dimethylaminoethyl acrylate is too low, and a catalyst needs to be used to improve the reaction efficiency. However, using the ZSM-5 molecular sieve supported SnCl4 catalyst commonly used in catalytic esterification reactions has problems such as low yield of the product dimethylaminoethyl acrylate and poor product purity. Therefore, it is urgent to develop a catalyst suitable for esterification synthesis of dimethylaminoethyl acrylate. Summary of the Invention

[0006] To overcome the above problems, the present invention provides a catalyst, a preparation method and an application thereof, and a synthesis method of dimethylaminoethyl acrylate.

[0007] To achieve the above technical objectives, the present invention adopts the following technical solutions:

[0008] In a first aspect of the present invention, there is provided a catalyst which uses HZSM-5 molecular sieve as a carrier and is loaded with calcium salt, tin salt and zinc salt.

[0009] In a second aspect of the present invention, there is provided a preparation method of the catalyst according to the first aspect, including the following steps:

[0010] (1) Immerse the HZSM-5 molecular sieve in a mixed solution of calcium salt, tin salt and zinc salt, take it out and dry it after standing for a specified time to obtain a first precursor material;

[0011] (2) Perform a first heat treatment on the first precursor material to obtain a second precursor material;

[0012] (3) Perform a second heat treatment on the second precursor material to obtain the catalyst.

[0013] In a third aspect of the present invention, there is provided an application of the above catalyst in catalytic esterification reaction.

[0014] In a fourth aspect of the present invention, there is provided a synthesis method of dimethylaminoethyl acrylate, including:

[0015] Using acrylic acid and N,N-dimethylethanolamine as raw materials, under the catalysis of the catalyst described in the first aspect, dimethylaminoethyl acrylate is synthesized.

[0016] The beneficial effects of the present invention are as follows:

[0017] (1) The present invention relates to the technical field of organic synthesis, and specifically relates to a catalyst, a preparation method and an application thereof, and a synthesis method of dimethylaminoethyl acrylate. In the present invention, acrylic acid and N,N-dimethylethanolamine are used as raw materials, and the HZSM-5 molecular sieve supported calcium-zinc-tin composite catalyst CaCl2-ZnCl2-SnCl4-HZSM-5 is used as a catalyst, which can efficiently synthesize dimethylaminoethyl acrylate. Using the HZSM-5 molecular sieve supported calcium-zinc-tin composite catalyst CaCl2-ZnCl2-SnCl4-HZSM-5 as a catalyst can not only efficiently catalyze the esterification reaction, but also has a high yield and high purity of dimethylaminoethyl acrylate, and reduces the generation of a large number of by-products.

[0018] (2) It was found that when using the ZSM-5 molecular sieve supported SnCl4 catalyst commonly used in catalytic esterification reaction, there were problems of low yield of dimethylaminoethyl acrylate and poor product purity. This was because the Lewis acidity of the ZSM-5 molecular sieve supported SnCl4 catalyst was too strong, resulting in an increase in side reactions, and thus the low yield of dimethylaminoethyl acrylate and poor product purity in the end. After adding calcium salt, the yield increased significantly. The main reason was that the introduction of calcium could neutralize the strong acidic sites of HZSM-5, reduce side reactions, and at the same time retain the medium-strength Brønsted acid centers to promote the esterification reaction. Compared with directly using the HZSM-5 molecular sieve supported calcium-tin composite catalyst CaCl2-SnCl4-HZSM-5, the HZSM-5 molecular sieve supported calcium-zinc-tin composite catalyst CaCl2-ZnCl2-SnCl4-HZSM-5 had a higher yield in the catalytic reaction for synthesizing dimethylaminoethyl acrylate. This was because Zn further increased the Lewis acid sites of the catalyst, promoted the nucleophilic attack of the alcohol, and accelerated the esterification reaction; at the same time, Zn modification could extend the service life of the catalyst. Description of the Drawings

[0019] The specification drawings forming a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention.

[0020] Figure 1 It is the infrared spectrum of the HZSM-5 molecular sieve supported calcium-zinc-tin composite catalyst CaCl2-ZnCl2-SnCl4-HZSM-5 prepared in Example 1. Detailed Description of the Invention

[0021] It should be noted that the following detailed descriptions are all exemplary and are intended to provide a further description of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs.

[0022] It should be noted that the terms used here are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used here, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or their combinations.

[0023] The first typical embodiment of the present invention provides a catalyst which uses a HZSM-5 molecular sieve as a carrier and is loaded with calcium salt, tin salt, and zinc salt.

[0024] In one or more embodiments, the calcium salt is selected from one or both of calcium chloride and calcium nitrate, preferably calcium chloride.

[0025] In one or more embodiments, the tin salt is selected from tin tetrachloride.

[0026] In one or more embodiments, the zinc salt is selected from one or both of zinc chloride and zinc nitrate, preferably zinc chloride.

[0027] A second exemplary embodiment of the present invention provides a method for preparing the catalyst described in the first aspect, comprising the following steps:

[0028] (1) Immerse the HZSM-5 molecular sieve in a mixed solution of a calcium salt, a tin salt, and a zinc salt, take it out and dry it after standing for a defined time to obtain a first precursor material;

[0029] (2) Perform a first heat treatment on the first precursor material to obtain a second precursor material;

[0030] (3) Perform a second heat treatment on the second precursor material to obtain the catalyst.

[0031] In one or more embodiments, in step (1), the mass fraction of the calcium salt is 12-18%, preferably 15%.

[0032] In one or more embodiments, in step (1), the mass fraction of the tin salt is 8-12%, preferably 10%.

[0033] In one or more embodiments, in step (1), the mass fraction of the zinc salt is 8-12%, preferably 10%.

[0034] In one or more embodiments, in step (1), the defined time is 20-30 h, preferably 24 h.

[0035] In one or more embodiments, in step (1), the drying temperature is 140-180 °C, preferably 150 °C; the drying time is 5-8 h, preferably 6 h.

[0036] In one or more embodiments, in step (2), the temperature of the first heat treatment is 240-280 °C, preferably 250 °C; the time of the first heat treatment is 2.5-4 h, preferably 3 h.

[0037] In one or more embodiments, in step (3), the temperature of the second heat treatment is 340-380 °C, preferably 350 °C; the time of the second heat treatment is 1.5-3 h, preferably 2 h.

[0038] The third typical embodiment of the present invention provides the application of the above catalyst in the catalytic esterification reaction.

[0039] In one or more embodiments, the esterification reaction includes synthesizing dimethylaminoethyl acrylate from acrylic acid and N,N-dimethylethanolamine as raw materials.

[0040] The fourth typical embodiment of the present invention provides a method for synthesizing dimethylaminoethyl acrylate, which includes:

[0041] Using acrylic acid and N,N-dimethylethanolamine as raw materials, and synthesizing dimethylaminoethyl acrylate under the catalysis of the catalyst described in the first aspect.

[0042] In one or more embodiments, the reaction temperature is 120-180 °C, preferably 150 °C.

[0043] In order to enable those skilled in the art to more clearly understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with specific examples.

[0044] In the present invention, a micro fixed-bed reactor is used to synthesize dimethylaminoethyl acrylate. The catalyst is filled into the micro fixed-bed reactor, quartz sand is filled at the top and bottom of the catalyst respectively, and quartz wool is used to separate the catalyst from the quartz sand.

[0045] Example 1

[0046] Synthesis of HZSM-5 molecular sieve supported calcium-zinc-tin composite catalyst CaCl2-ZnCl2-SnCl4-HZSM-5:

[0047] (1) Calcium chloride, tin tetrachloride, and zinc chloride are respectively dissolved in deionized water to prepare a mixed solution containing calcium salt, tin salt, and zinc salt, where the mass fraction of calcium chloride is 15%, the mass fraction of tin salt is 10%, and the mass fraction of zinc salt is 10%.

[0048] (2) The HZSM-5 molecular sieve is impregnated in the mixed solution of step (1), impregnated for 24 h, the solid is filtered out, and vacuum dried at 150 °C for 6 h to obtain the first precursor material;

[0049] (2) The first precursor material is calcined in a muffle furnace at 250 °C for 3 h to obtain the second precursor material;

[0050] (3) The second precursor material is further calcined in a muffle furnace at 350 °C for 2 h to obtain the HZSM-5 molecular sieve supported calcium-zinc-tin composite catalyst CaCl2-ZnCl2-SnCl4-HZSM-5.

[0051] The infrared spectrum of the CaCl2-ZnCl2-SnCl4-HZSM-5 composite catalyst supported on HZSM-5 zeolite prepared in this example is as follows Figure 1 as shown. It can be seen from Figure 1 that the broad peak at 3630.29 cm -1 indicates hydroxyl (-OH) or adsorbed water, which is a common feature of HZSM-5 zeolite, indicating the presence of surface active sites; the strong peak at 1637.10 cm -1 represents C=O (carbonyl group), which may be the residual organic template agent or metal coordination carbonyl in the zeolite synthesis; the strong peak at 1099.28 cm -1 represents the stretching vibration of Si-O (zeolite framework), indicating that the carrier is a silicon-based zeolite; the strong peak at 795.08 cm -1 represents the vibration of metal oxides (CaO, ZnO, SnO2), and the vibration frequencies of calcium, zinc, and tin oxides partially overlap in this region; the weak peak at 546.12 cm -1 represents metal coordination vibration (M-O / M-Sn) or lattice distortion, which is due to the large difference in ionic radii of calcium, zinc, and tin If the three coordinate synergistically or there is lattice distortion, characteristic vibration will occur in this region.

[0052] Comparative Example 1

[0053] Synthesis of SnCl4-HZSM-5 composite catalyst supported on HZSM-5 zeolite:

[0054] (1) Dissolve stannic chloride in deionized water to prepare a mixed solution containing stannic salt, where the mass fraction of stannic salt is 10%.

[0055] (2) Immerse HZSM-5 zeolite in the solution of step (1) for 24 h, filter out the solid, and vacuum dry it at 150 °C for 6 h to obtain the first precursor material;

[0056] (2) Calcine the first precursor material in a muffle furnace at 250 °C for 3 h to obtain the second precursor material;

[0057] (3) Calcine the second precursor material in a muffle furnace at 350 °C for 2 h to obtain the SnCl4-HZSM-5 composite catalyst supported on HZSM-5 zeolite.

[0058] Comparative Example 2

[0059] Synthesis of CaCl2-SnCl4-HZSM-5 composite catalyst supported on HZSM-5 zeolite:

[0060] (1) Dissolve calcium chloride and tin tetrachloride in deionized water respectively to prepare a mixed solution containing calcium salt and tin salt, where the mass fraction of calcium chloride is 15% and the mass fraction of tin salt is 10%.

[0061] (2) Immerse HZSM-5 molecular sieve in the mixed solution of step (1) for 24 h, filter out the solid, and vacuum dry it at 150 °C for 6 h to obtain the first precursor material;

[0062] (2) Calcine the first precursor material in a muffle furnace at 250 °C for 3 h to obtain the second precursor material;

[0063] (3) Calcine the second precursor material in a muffle furnace at 350 °C for 2 h to obtain the HZSM-5 molecular sieve supported calcium-tin composite catalyst CaCl2-SnCl4-HZSM-5.

[0064] Comparative Example 3

[0065] Synthesis of HZSM-5 molecular sieve supported calcium-zinc-tin composite catalyst ZnCl2-SnCl4-HZSM-5:

[0066] (1) Dissolve tin tetrachloride and zinc chloride in deionized water respectively to prepare a mixed solution containing tin salt and zinc salt, where the mass fraction of tin salt is 10% and the mass fraction of zinc salt is 10%.

[0067] (2) Immerse HZSM-5 molecular sieve in the mixed solution of step (1) for 24 h, filter out the solid, and vacuum dry it at 150 °C for 6 h to obtain the first precursor material;

[0068] (2) Calcine the first precursor material in a muffle furnace at 250 °C for 3 h to obtain the second precursor material;

[0069] (3) Calcine the second precursor material in a muffle furnace at 350 °C for 2 h to obtain the HZSM-5 molecular sieve supported calcium-zinc-tin composite catalyst ZnCl2-SnCl4-HZSM-5.

[0070] Example 2

[0071] Synthesis of dimethylaminoethyl acrylate:

[0072] Using the HZSM-5 zeolite supported calcium-zinc-tin composite catalyst CaCl2-ZnCl2-SnCl4-HZSM-5 prepared in Example 1 as the catalyst, the preheater was heated to 80 °C, and the reactor was heated to 120 °C. The mass ratio of raw material acrylic acid, N,N-dimethylethanolamine and inhibitor phenothiazine was 1:1.3:0.005. After mixing, it was fed into a micro fixed-bed reactor. Nitrogen was used as the carrier gas, and the raw material space velocity was 0.5 g / mL.cat.h. The reaction was carried out under atmospheric pressure. The outlet was condensed by a condenser to obtain a crude product of dimethylaminoethyl acrylate containing water. After vacuum distillation, the finished product of dimethylaminoethyl acrylate was obtained, with a yield of 80%, a purity of 99.7%, and a water content of 0.03%.

[0073] Example 3

[0074] Synthesis of dimethylaminoethyl acrylate:

[0075] Using the HZSM-5 zeolite supported calcium-zinc-tin composite catalyst CaCl2-ZnCl2-SnCl4-HZSM-5 prepared in Example 1 as the catalyst, the preheater was heated to 80 °C, and the reactor was heated to 150 °C. The mass ratio of raw material acrylic acid, N,N-dimethylethanolamine and inhibitor phenothiazine was 1:1.3:0.005. After mixing, it was fed into a micro fixed-bed reactor. Nitrogen was used as the carrier gas, and the raw material space velocity was 0.5 g / mL.cat.h. The reaction was carried out under atmospheric pressure. The outlet was condensed by a condenser to obtain a crude product of dimethylaminoethyl acrylate containing water. After vacuum distillation, the finished product of dimethylaminoethyl acrylate was obtained, with a yield of 85%, a purity of 99.7%, and a water content of 0.01%.

[0076] Example 4

[0077] Synthesis of dimethylaminoethyl acrylate:

[0078] Using the HZSM-5 zeolite supported calcium-zinc-tin composite catalyst CaCl2-ZnCl2-SnCl4-HZSM-5 prepared in Example 1 as the catalyst, the preheater was heated to 80 °C, and the reactor was heated to 180 °C. The mass ratio of raw material acrylic acid, N,N-dimethylethanolamine and inhibitor phenothiazine was 1:1.3:0.005. After mixing, it was fed into a micro fixed-bed reactor. Nitrogen was used as the carrier gas, and the raw material space velocity was 0.5 g / mL.cat.h. The reaction was carried out under atmospheric pressure. The outlet was condensed by a condenser to obtain a crude product of dimethylaminoethyl acrylate containing water. After vacuum distillation, the finished product of dimethylaminoethyl acrylate was obtained, with a yield of 80%, a purity of 99.6%, and a water content of 0.01%.

[0079] Example 5

[0080] Synthesis of dimethylaminoethyl acrylate:

[0081] Using the HZSM-5 zeolite-supported calcium-zinc-tin composite catalyst CaCl2-ZnCl2-SnCl4-HZSM-5 prepared in Example 1 as the catalyst, the preheater was heated to 80 °C, the reactor was heated to 150 °C, the mass ratio of raw material acrylic acid, N,N-dimethyl ethanolamine and inhibitor phenothiazine was 1:1.3:0.005. After mixing, it was fed into a micro fixed-bed reactor. Nitrogen was used as the carrier gas, the raw material space velocity was 0.4 g / mL.cat.h, and the reaction was carried out under atmospheric pressure. The outlet was condensed by a condenser to obtain a crude product of dimethylaminoethyl acrylate containing water. After vacuum distillation, the finished product of dimethylaminoethyl acrylate was obtained, with a yield of 89%, a purity of 99.8%, and a water content of 0.02%.

[0082] Example 6

[0083] Synthesis of dimethylaminoethyl acrylate:

[0084] Using the HZSM-5 zeolite-supported calcium-zinc-tin composite catalyst CaCl2-ZnCl2-SnCl4-HZSM-5 prepared in Example 1 as the catalyst, the preheater was heated to 80 °C, the reactor was heated to 150 °C, the mass ratio of raw material acrylic acid, N,N-dimethyl ethanolamine and inhibitor phenothiazine was 1:1.3:0.005. After mixing, it was fed into a micro fixed-bed reactor. Nitrogen was used as the carrier gas, the raw material space velocity was 0.3 g / mL.cat.h, and the reaction was carried out under atmospheric pressure. The outlet was condensed by a condenser to obtain a crude product of dimethylaminoethyl acrylate containing water. After vacuum distillation, the finished product of dimethylaminoethyl acrylate was obtained, with a yield of 91%, a purity of 99.8%, and a water content of 0.03%.

[0085] Comparative Example 4

[0086] Synthesis of dimethylaminoethyl acrylate:

[0087] Using the HZSM-5 zeolite-supported tin composite catalyst SnCl4-HZSM-5 prepared in Comparative Example 1 as the catalyst, the preheater was heated to 80 °C, the reactor was heated to 150 °C, the mass ratio of raw material acrylic acid, N,N-dimethyl ethanolamine and inhibitor phenothiazine was 1:1.3:0.005. After mixing, it was fed into a micro fixed-bed reactor. Nitrogen was used as the carrier gas, the raw material space velocity was 0.5 g / mL.cat.h, and the reaction was carried out under atmospheric pressure. The outlet was condensed by a condenser to obtain a crude product of dimethylaminoethyl acrylate containing water. After vacuum distillation, the finished product of dimethylaminoethyl acrylate was obtained, with a yield of 62%, a purity of 99.2%, and a water content of 0.02%.

[0088] Comparative Example 5

[0089] Synthesis of dimethylaminoethyl acrylate:

[0090] Using the CaCl2-SnCl4-HZSM-5 catalyst supported on HZSM-5 zeolite prepared in Comparative Example 2, the preheater was heated to 80 °C, the reactor was heated to 150 °C, the mass ratio of raw material acrylic acid, N,N-dimethylethanolamine and inhibitor phenothiazine was 1:1.3:0.005. After mixing, it was fed into a micro fixed-bed reactor. Nitrogen was used as the carrier gas, the space velocity of the raw material was 0.5 g / mL.cat.h, and the reaction was carried out under atmospheric pressure. The outlet was condensed by a condenser to obtain a crude product of dimethylaminoethyl acrylate containing water. After vacuum distillation, the finished product of dimethylaminoethyl acrylate was obtained, with a yield of 65%, a purity of 99.4%, and a water content of 0.01%.

[0091] Comparative Example 6

[0092] Synthesis of dimethylaminoethyl acrylate:

[0093] Using the ZnCl2-SnCl4-HZSM-5 catalyst supported on HZSM-5 zeolite prepared in Comparative Example 3, the preheater was heated to 80 °C, the reactor was heated to 150 °C, the mass ratio of raw material acrylic acid, N,N-dimethylethanolamine and inhibitor phenothiazine was 1:1.3:0.005. After mixing, it was fed into a micro fixed-bed reactor. Nitrogen was used as the carrier gas, the space velocity of the raw material was 0.5 g / mL.cat.h, and the reaction was carried out under atmospheric pressure. The outlet was condensed by a condenser to obtain a crude product of dimethylaminoethyl acrylate containing water. After vacuum distillation, the finished product of dimethylaminoethyl acrylate was obtained, with a yield of 68%, a purity of 99.6%, and a water content of 0.01%.

[0094] Example 7

[0095] Under the process conditions of Example 6, the catalyst life was investigated. When the device had been running for 25 days, the reaction solution was analyzed by GC. The residues of raw material acrylic acid and N,N-dimethylethanolamine both exceeded 2%, and the yield decreased to 87%. The reaction was stopped and the catalyst was regenerated.

[0096] Operation method for catalyst regeneration: The temperature of the reaction furnace was lowered to 90 °C, and at the same time, nitrogen was blown as a companion. The feeding of anhydrous ethanol was started to clean the pipeline and the reactor until the ethanol was colorless or light yellow. The ethanol feeding pump was closed, and the pipeline was continuously purged with nitrogen for 30 min. The programmed temperature reduction and passivation were started: from 100 °C to 200 °C, which took 200 min and was maintained for 60 min; from 200 °C to 450 °C, which took 150 min and was maintained for 180 min.

[0097] After roasting is completed, the temperature is lowered to the reaction temperature, the preheater is set to the required conditions, and feeding is started. After the catalyst is activated, it can continue to operate continuously for about 20 days. The reaction solution is taken for GC analysis. The residues of raw material acrylic acid and N,N-dimethylethanolamine both exceed 2%. After the activity starts to decrease, the reaction is stopped. Repeating the catalyst regeneration operation can restore the activity, but the duration gradually decreases. The main reason may be catalyst loss. It is expected that after 5 recoveries, the running time will be less than 10 days and the catalyst needs to be refilled. The specific recycling effect of the catalyst is shown in Table 1 below.

[0098] Table 1 Recycling effect of the catalyst

[0099] Catalyst type Running duration (d) Yield 1 New catalyst 25 91％ 2 First regeneration 20 90％ 3 Second regeneration 17 88％ 4 Third regeneration 15 87％ 5 Fourth regeneration 13 86％ 6 Fifth regeneration 10 Below 85%, stop the reaction and refill with new catalyst

[0100] Conclusion: There are problems of low yield of dimethylaminoethyl acrylate product and poor product purity when using the ZSM-5 molecular sieve supported SnCl4 catalyst commonly used in catalytic esterification reaction. This is because the Lewis acidity of the ZSM-5 molecular sieve supported SnCl4 catalyst is too strong, which will form a large number of by-products, resulting in low yield of dimethylaminoethyl acrylate and poor product purity in the end. After adding calcium salt, the yield increases significantly. The main reason is that the introduction of calcium can neutralize the strong acid sites of HZSM-5, reduce side reactions, and at the same time retain medium-strength Brønsted acid centers to promote the esterification reaction. Compared with directly using the HZSM-5 molecular sieve supported calcium-tin composite catalyst CaCl2-SnCl4-HZSM-5, the yield of dimethylaminoethyl acrylate synthesized by the HZSM-5 molecular sieve supported calcium-zinc-tin composite catalyst CaCl2-ZnCl2-SnCl4-HZSM-5 catalytic reaction is higher. This is because Zn further increases the Lewis acid sites of the catalyst, promotes the nucleophilic attack of the alcohol, and accelerates the esterification reaction; at the same time, Zn modification can extend the life of the catalyst.

[0101] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A catalyst, characterized in that, It uses HZSM-5 molecular sieve as a carrier and is loaded with calcium salt, tin salt and zinc salt.

2. The catalyst according to claim 1, characterized in that, The calcium salt is selected from one or both of calcium chloride and calcium nitrate; The tin salt is selected from tin tetrachloride; The zinc salt is selected from one or both of zinc chloride and zinc nitrate.

3. The method for preparing the catalyst according to claim 1 or 2, characterized in that, It includes the following steps: (1) Immerse the HZSM-5 molecular sieve in a mixed solution of calcium salt, tin salt and zinc salt, take it out and dry it after standing for a defined time to obtain a first precursor material; (2) Perform a first heat treatment on the first precursor material to obtain a second precursor material; (3) Perform a second heat treatment on the second precursor material to obtain a catalyst.

4. The preparation method according to claim 3, characterized in that, In step (1), the mass fraction of the calcium salt is 12-18%; In step (1), the mass fraction of the tin salt is 8-12%; In step (1), the mass fraction of the zinc salt is 8-12%; In step (1), the defined time is 20-30 h.

5. The preparation method according to claim 3, characterized in that, In step (1), the drying temperature is 140-180 °C; the drying time is 5-8 h.

6. The preparation method according to claim 3, characterized in that, In step (2), the temperature of the first heat treatment is 240-280 °C; the time of the first heat treatment is 2.5-4 h; The temperature of the second heat treatment is 340-380 °C; the time of the second heat treatment is 1.5-3 h.

7. Application of the catalyst according to claim 1 or 2 in catalytic esterification reaction.

8. The application according to claim 7, wherein, The esterification reaction includes synthesizing dimethylaminoethyl acrylate from acrylic acid and N,N-dimethylethanolamine as raw materials.

9. A method for synthesizing dimethylaminoethyl acrylate, characterized in that, It includes: Using acrylic acid and N,N-dimethylethanolamine as raw materials, and synthesizing dimethylaminoethyl acrylate under the catalysis of the catalyst according to claim 1 or 2.

10. The synthesis method according to claim 9, characterized in that, The reaction temperature is 120-180 °C.

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