A catalyst, its preparation method and application, and a method for synthesizing dimethylaminoethyl acrylate.

Abstract

This invention relates to the field of organic synthesis technology, specifically to a catalyst, its preparation method and application, and a method for synthesizing dimethylaminoethyl acrylate. In this invention, acrylic acid and N,N-dimethylethanolamine are used as raw materials, and a calcium-zinc-tin composite catalyst (CaCl2-ZnCl2-SnCl4-HZSM-5) supported on HZSM-5 molecular sieve is used as the catalyst to efficiently synthesize dimethylaminoethyl acrylate. Using the HZSM-5 molecular sieve-supported calcium-zinc-tin composite catalyst (CaCl2-ZnCl2-SnCl4-HZSM-5) not only efficiently catalyzes the esterification reaction but also results in high yield and high purity of dimethylaminoethyl acrylate, while reducing the formation of a large number of byproducts.

Description

Technical Field

[0001] This invention relates to the field of organic synthesis technology, specifically to a catalyst, its preparation method and application, and a method for synthesizing dimethylaminoethyl acrylate. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] Dimethylaminoethyl acrylate (DA) is an important methacrylate. Because its molecule contains active groups such as vinyl and tertiary amine groups, it can be polymerized to synthesize polymers with active amine or quaternary ammonium groups. It is widely used in water treatment, papermaking, coatings, pharmaceuticals, oilfield chemicals, adhesives, fiber auxiliaries, and plastic and rubber modification.

[0004] Currently, there are five main methods for producing dimethylaminoethyl acrylate (DME): esterification, transesterification, high-temperature pyrolysis, chloropropaneyl chloride, and acryloyl chloride. Transesterification is the primary method, involving the transesterification reaction of methyl acrylate with dimethylaminoethanol. However, transesterification has several drawbacks: because the raw material methyl acrylate and the byproduct methanol form an azeotrope, a large excess of methyl acrylate is required to improve the conversion rate; to increase the yield, the methanol-methyl acrylate azeotrope is carried out of the system, shifting the equilibrium towards the synthesis of DME; and the azeotrope of methyl acrylate and methanol needs to be further separated through extraction and distillation, resulting in high energy consumption and large equipment investment. High-temperature pyrolysis overcomes the difficulties in separating the methanol-methyl acrylate azeotrope and the low purity of the product in transesterification, but it is complex and difficult to industrialize. The hydrogen chloride byproduct produced by the chloropropane acyl chloride process and the acyl chloride process needs to be absorbed with alkaline substances, which can easily cause equipment corrosion and environmental pollution. Moreover, acyl chlorides are toxic and difficult to industrialize. In contrast, the esterification method involves the direct dehydration and esterification of acrylic acid and dimethylaminoethanol in the presence of concentrated sulfuric acid as a dehydrating agent. The overall process is simple and suitable for industrial application.

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

[0006] To overcome the above problems, the present invention provides a catalyst, its preparation method and application, and a method for synthesizing dimethylaminoethyl acrylate.

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

[0008] In a first aspect, the present invention provides a catalyst supported on HZSM-5 molecular sieve and loaded with calcium salt, tin salt and zinc salt.

[0009] A second aspect of the present invention provides a method for preparing the catalyst described in the first aspect, comprising the following steps:

[0010] (1) HZSM-5 molecular sieve was immersed in a mixed solution of calcium salt, tin salt and zinc salt, and after standing for a specified time, it was taken out and dried to obtain the first precursor material.

[0011] (2) The first precursor material is subjected to a first heat treatment to obtain the second precursor material;

[0012] (3) The catalyst is obtained by subjecting the second precursor material to a second heat treatment.

[0013] A third aspect of the present invention provides the application of the above-described catalyst in catalytic esterification reactions.

[0014] A fourth aspect of the present invention provides a method for synthesizing dimethylaminoethyl acrylate, comprising:

[0015] Dimethylaminoethyl acrylate was synthesized from acrylic acid and N,N-dimethylethanolamine under the catalysis of the catalyst described in the first aspect.

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

[0017] (1) This invention relates to the field of organic synthesis technology, specifically to a catalyst, its preparation method and application, and a method for synthesizing dimethylaminoethyl acrylate. In this invention, acrylic acid and N,N-dimethylethanolamine are used as raw materials, and a calcium-zinc-tin composite catalyst CaCl2-ZnCl2-SnCl4-HZSM-5 supported on HZSM-5 molecular sieve is used as the catalyst to efficiently synthesize dimethylaminoethyl acrylate. Using the calcium-zinc-tin composite catalyst CaCl2-ZnCl2-SnCl4-HZSM-5 supported on HZSM-5 molecular sieve as the catalyst not only efficiently catalyzes the esterification reaction, but also results in high yield and high purity of dimethylaminoethyl acrylate, while reducing the formation of a large number of byproducts.

[0018] (2) Studies have found that the ZSM-5 molecular sieve-supported SnCl4 catalyst commonly used in catalytic esterification reactions suffers from low yield and poor purity of the product dimethylaminoethyl acrylate. This is because the Lewis acidity of the ZSM-5 molecular sieve-supported SnCl4 catalyst is too strong, leading to an increase in side reactions, which in turn results in a low yield and poor purity of the final dimethylaminoethyl acrylate product. However, the yield increases significantly after the addition of calcium salt. This is mainly because the introduction of calcium can neutralize the strong acidic sites of HZSM-5, reduce side reactions, and at the same time retain the moderately strong Brønsted acid centers, promoting the esterification reaction. Compared to directly using the calcium-tin composite catalyst CaCl2-SnCl4-HZSM-5 supported on HZSM-5 molecular sieve, the HZSM-5 molecular sieve-supported calcium-zinc-tin composite catalyst CaCl2-ZnCl2-SnCl4-HZSM-5 catalyzes the synthesis of dimethylaminoethyl acrylate. This is because Zn further increases the Lewis acid sites on the catalyst, promotes the nucleophilic attack of alcohols, and accelerates the esterification reaction; at the same time, Zn modification can extend the catalyst lifetime. Attached Figure Description

[0019] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

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

[0021] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0022] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, 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 combinations thereof.

[0023] In a first typical embodiment of the present invention, a catalyst is provided which uses HZSM-5 molecular sieve as a support 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 typical embodiment of the present invention provides a method for preparing the catalyst described in the first aspect, comprising the following steps:

[0028] (1) HZSM-5 molecular sieve was immersed in a mixed solution of calcium salt, tin salt and zinc salt, and after standing for a specified time, it was taken out and dried to obtain the first precursor material.

[0029] (2) The first precursor material is subjected to a first heat treatment to obtain the second precursor material;

[0030] (3) The catalyst is obtained by subjecting the second precursor material to a second heat treatment.

[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 time limit is 20 to 30 hours, preferably 24 hours.

[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 hours, preferably 6 hours.

[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 hours, preferably 3 hours.

[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 hours, preferably 2 hours.

[0038] A third typical embodiment of the present invention provides the application of the above-described catalyst in a catalytic esterification reaction.

[0039] In one or more embodiments, the esterification reaction includes the synthesis of dimethylaminoethyl acrylate from acrylic acid and N,N-dimethylethanolamine.

[0040] A fourth typical embodiment of the present invention provides a method for synthesizing dimethylaminoethyl acrylate, comprising:

[0041] Dimethylaminoethyl acrylate was synthesized from acrylic acid and N,N-dimethylethanolamine 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] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0044] In this invention, a micro fixed-bed reactor is used to synthesize dimethylaminoethyl acrylate. The catalyst is packed into the micro fixed-bed reactor, and quartz sand is packed at the top and bottom of the catalyst, with quartz wool 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) Dissolve calcium chloride, tin tetrachloride and zinc chloride in deionized water to prepare a mixed solution containing calcium salt, tin salt and zinc salt, wherein 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 was immersed in the mixed solution of step (1) for 24 hours, the solid was filtered out and dried under vacuum at 150°C for 6 hours to obtain the first precursor material.

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

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

[0051] The infrared spectrum of the calcium-zinc-tin composite catalyst CaCl2-ZnCl2-SnCl4-HZSM-5 supported on HZSM-5 molecular sieve prepared in this embodiment is as follows: Figure 1 As shown, from Figure 1 It can be seen from 3630.29cm -1 The broad peak at 1637.10 cm⁻¹ indicates hydroxyl (-OH) or adsorbed water, a common characteristic of HZSM-5 molecular sieves, indicating the presence of surface active sites; -1 The strong peak at 1099.28 cm⁻¹ indicates a C=O (carbonyl) group, which may be a residual organic template agent or a metal-coordinated carbonyl group from the molecular sieve synthesis; -1 The strong peak at 795.08 cm⁻¹ indicates the Si-O stretching vibration (molecular sieve framework), suggesting that the support is a silicon-based molecular sieve; -1 The strong peak at 546.12 cm⁻¹ indicates the vibrations of metal oxides (CaO, ZnO, SnO₂), and the vibrational frequencies of calcium, zinc, and tin oxides partially overlap in this region; -1 The weak peak at that point indicates metal coordination vibration (MO / M-Sn) or lattice distortion, which is due to the large differences in the ionic radii of calcium, zinc, and tin. If the three elements coordinate in concert or the lattice is distorted, characteristic vibrations will be generated in this region.

[0052] Comparative Example 1

[0053] Synthesis of HZSM-5 molecular sieve-supported tin composite catalyst SnCl4-HZSM-5:

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

[0055] (2) The HZSM-5 molecular sieve was immersed in the solution of step (1) for 24 hours, the solid was filtered out and dried under vacuum at 150°C for 6 hours to obtain the first precursor material.

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

[0057] (3) The second precursor material was calcined in a muffle furnace at 350°C for 2 hours to obtain the HZSM-5 molecular sieve supported tin composite catalyst SnCl4-HZSM-5.

[0058] Comparative Example 2

[0059] Synthesis of HZSM-5 molecular sieve-supported calcium-tin composite catalyst CaCl2-SnCl4-HZSM-5:

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

[0061] (2) The HZSM-5 molecular sieve was immersed in the mixed solution of step (1) for 24 hours, the solid was filtered out and dried under vacuum at 150°C for 6 hours to obtain the first precursor material.

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

[0063] (3) The second precursor material was calcined in a muffle furnace at 350°C for 2 hours 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 to prepare a mixed solution containing tin salt and zinc salt, wherein the mass fraction of tin salt is 10% and the mass fraction of zinc salt is 10%.

[0067] (2) The HZSM-5 molecular sieve was immersed in the mixed solution of step (1) for 24 hours, the solid was filtered out and dried under vacuum at 150°C for 6 hours to obtain the first precursor material.

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

[0069] (3) The second precursor material was calcined in a muffle furnace at 350°C for 2 hours 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 calcium-zinc-tin composite catalyst CaCl2-ZnCl2-SnCl4-HZSM-5 supported on HZSM-5 molecular sieve 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 the raw material acrylic acid, N,N-dimethylethanolamine and the polymerization inhibitor phenothiazine was 1:1.3:0.005. After mixing, the mixture was fed into a micro fixed-bed reactor with nitrogen as the carrier gas and a raw material space velocity of 0.5 g / mL·cat·h. The reaction was carried out under normal 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 calcium-zinc-tin composite catalyst CaCl2-ZnCl2-SnCl4-HZSM-5 supported on HZSM-5 molecular sieve 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 the raw material acrylic acid, N,N-dimethylethanolamine and the polymerization inhibitor phenothiazine was 1:1.3:0.005. After mixing, the mixture was fed into a micro fixed-bed reactor with nitrogen as the carrier gas and a raw material space velocity of 0.5 g / mL·cat·h. The reaction was carried out under normal pressure. The product was condensed in a condenser to obtain a crude product of dimethylaminoethyl acrylate containing water. After vacuum distillation, the final 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 calcium-zinc-tin composite catalyst CaCl2-ZnCl2-SnCl4-HZSM-5 supported on HZSM-5 molecular sieve 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 the raw material acrylic acid, N,N-dimethylethanolamine and the polymerization inhibitor phenothiazine was 1:1.3:0.005. After mixing, the mixture was fed into a micro fixed-bed reactor with nitrogen as the carrier gas and a raw material space velocity of 0.5 g / mL·cat·h. The reaction was carried out under normal 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 calcium-zinc-tin composite catalyst CaCl2-ZnCl2-SnCl4-HZSM-5 supported on HZSM-5 molecular sieve 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 the raw material acrylic acid, N,N-dimethylethanolamine and the polymerization inhibitor phenothiazine was 1:1.3:0.005. After mixing, the mixture was fed into a micro fixed-bed reactor with nitrogen as the carrier gas and a raw material space velocity of 0.4 g / mL·cat·h. The reaction was carried out under normal pressure. The product was condensed in a condenser to obtain a crude product of dimethylaminoethyl acrylate containing water. After vacuum distillation, the final 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 calcium-zinc-tin composite catalyst CaCl2-ZnCl2-SnCl4-HZSM-5 supported on HZSM-5 molecular sieve 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 the raw material acrylic acid, N,N-dimethylethanolamine and the polymerization inhibitor phenothiazine was 1:1.3:0.005. After mixing, the mixture was fed into a micro fixed-bed reactor with nitrogen as the carrier gas and a raw material space velocity of 0.3 g / mL·cat·h. The reaction was carried out under normal 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 molecular sieve-supported tin composite catalyst SnCl4-HZSM-5 prepared in Comparative Example 1 as the catalyst, the preheater was heated to 80℃, and the reactor was heated to 150℃. The mass ratio of the raw material acrylic acid, N,N-dimethylethanolamine and the polymerization inhibitor phenothiazine was 1:1.3:0.005. After mixing, the mixture was fed into a micro fixed-bed reactor with nitrogen as the carrier gas and a raw material space velocity of 0.5 g / mL·cat·h. The reaction was carried out under normal pressure. The product was condensed in a condenser to obtain a crude product of dimethylaminoethyl acrylate containing water. After vacuum distillation, the final 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 calcium-tin composite catalyst CaCl2-SnCl4-HZSM-5 supported on HZSM-5 molecular sieve prepared in Comparative Example 2 as the catalyst, the preheater was heated to 80℃, and the reactor was heated to 150℃. The mass ratio of the raw material acrylic acid, N,N-dimethylethanolamine and the polymerization inhibitor phenothiazine was 1:1.3:0.005. After mixing, the mixture was fed into a micro fixed-bed reactor with nitrogen as the carrier gas and a raw material space velocity of 0.5 g / mL·cat·h. The reaction was carried out under normal pressure. The product was condensed in a condenser to obtain a crude product of dimethylaminoethyl acrylate containing water. After vacuum distillation, the final 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 HZSM-5 molecular sieve-supported zinc-tin composite catalyst ZnCl2-SnCl4-HZSM-5 prepared in Comparative Example 3 as the catalyst, the preheater was heated to 80℃, and the reactor was heated to 150℃. The mass ratio of the raw material acrylic acid, N,N-dimethylethanolamine and the polymerization inhibitor phenothiazine was 1:1.3:0.005. After mixing, the mixture was fed into a micro fixed-bed reactor with nitrogen as the carrier gas and a raw material space velocity of 0.5 g / mL·cat·h. The reaction was carried out under normal 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] Using the process conditions of Example 6, the catalyst lifetime was examined. After 25 days of operation, GC analysis of the reaction solution showed that the remaining amounts of the raw materials acrylic acid and N,N-dimethylethanolamine both exceeded 2%, and the yield dropped to 87%. The reaction was then stopped, and catalyst regeneration was carried out.

[0096] Catalyst regeneration procedure: Cool the reactor to 90°C while simultaneously purging with nitrogen. Begin feeding anhydrous ethanol to clean the pipelines and reactor until the ethanol is colorless or pale yellow. Then, shut off the ethanol feed pump and continue purging the pipelines with nitrogen for 30 minutes. Begin programmed temperature ramp-up passivation: ramp from 100°C to 200°C in 200 minutes and hold for 60 minutes; ramp from 200°C to 450°C in 150 minutes and hold for 180 minutes.

[0097] After calcination, the temperature was lowered to the reaction temperature, the preheater was set to the required conditions, and feeding began. After catalyst activation, it could run continuously for approximately 20 days. GC analysis of the reaction solution showed that the residual amounts of the raw materials acrylic acid and N,N-dimethylethanolamine both exceeded 2%, indicating a decrease in activity. The reaction was then stopped, and repeated catalyst regeneration restored activity, although the duration gradually decreased. This was likely due to catalyst loss; it was estimated that after five recycling cycles, the operating time would be less than 10 days, requiring catalyst reloading. The specific catalyst recycling efficiency is shown in Table 1 below.

[0098] Table 1. Catalyst recycling efficiency

[0099] Catalyst type Runtime (d) yield 1 New catalyst 25 91％ 2 First rebirth 20 90％ 3 Second regeneration 17 88％ 4 Third regeneration 15 87％ 5 Fourth regeneration 13 86％ 6 Fifth regeneration 10 If the catalyst concentration drops below 85%, stop the reaction and refill with a new catalyst.

[0100] Conclusion: The commonly used ZSM-5 molecular sieve-supported SnCl4 catalyst in catalytic esterification reactions suffers from low yield and poor purity of dimethylaminoethyl acrylate. This is because the Lewis acidity of the ZSM-5 molecular sieve-supported SnCl4 catalyst is too strong, leading to the formation of a large number of byproducts, resulting in low yield and poor purity of dimethylaminoethyl acrylate. However, the addition of calcium salt significantly increases the yield. This is mainly because the introduction of calcium neutralizes the strong acidic sites of HZSM-5, reducing side reactions, while retaining moderately strong Brønsted acid centers, thus promoting the esterification reaction. Compared to directly using the calcium-tin composite catalyst CaCl2-SnCl4-HZSM-5 supported on HZSM-5 molecular sieve, the HZSM-5 molecular sieve-supported calcium-zinc-tin composite catalyst CaCl2-ZnCl2-SnCl4-HZSM-5 catalyzes the synthesis of dimethylaminoethyl acrylate. This is because Zn further increases the Lewis acid sites on the catalyst, promotes the nucleophilic attack of alcohols, and accelerates the esterification reaction; at the same time, Zn modification can extend the catalyst lifetime.

[0101] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. Use of a catalyst in catalysing an esterification reaction, characterised in that, The catalyst has HZSM-5 molecular sieve as a carrier, and is loaded with CaO, ZnO and SnO2; the esterification reaction comprises synthesizing dimethylaminoethyl acrylate by using acrylic acid and N,N-dimethylethanolamine as raw materials; The preparation method of the catalyst comprises the following steps: (1) immersing HZSM-5 molecular sieve in a mixed solution of calcium salt, tin salt and zinc salt, taking out and drying after standing for a defined time to obtain a first precursor material; (2) obtaining a second precursor material by performing first heat treatment on the first precursor material; (3) obtaining the catalyst by performing second heat treatment on the second precursor material; In step (2), the temperature of the first heat treatment is 240-280 DEG C; the time of the first heat treatment is 2.5-4 h; In step (3), the temperature of the second heat treatment is 340-380 DEG C; the time of the second heat treatment is 1.5-3 h.

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

3. Use of the catalyst according to claim 1 in catalyzing esterification reactions, characterized in that, In step (1), the mass fraction of the calcium salt in the mixed solution is 12-18%; In step (1), the mass fraction of the tin salt in the mixed solution is 8-12%; In step (1), the mass fraction of the zinc salt in the mixed solution is 8-12%; In step (1), the defined time is 20-30 h.

4. Use of the catalyst according to claim 1 in catalyzing esterification reactions, characterized in that, In step (1), the temperature of the drying is 140-180 DEG C; the time of the drying is 5-8 h.

5. Use of the catalyst according to claim 1 in catalyzing esterification reactions, characterized in that, The temperature of the reaction is 120-180 DEG C.

Images