Catalyst for continuously preparing alpha-acetyl-gamma-butyrolactone, preparation method thereof and continuous preparation method of alpha-acetyl-gamma-butyrolactone

Abstract

The invention provides a catalyst for continuously preparing alpha-acetyl-gamma-butyrolactone, a preparation method of the catalyst and a continuous preparation method of the alpha-acetyl-gamma-butyrolactone. The preparation method of the catalyst for continuous preparation of alpha-acetyl-gamma-butyrolactone comprises the following steps: dipping a carrier in a first solution containing a magnesium source to obtain a first product; immersing the first product in a second solution containing a sodium source and a potassium source to obtain a second product; calcining the second product to obtain a third product; dipping the third product in a third solution containing a cesium source, and carrying out first stirring treatment to obtain a fourth product; and dipping the fourth product in a fourth solution containing Na3AlF6, and carrying out second stirring treatment to obtain the catalyst for continuous preparation of alpha-acetyl-gamma-butyrolactone. The cesium-magnesium-aluminum composite solid base catalyst with a high-activity interface is constructed through cesium-magnesium synergistic modification of a carrier.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of organic synthesis, in particular, to a catalyst for continuous preparation of α-acetyl-γ-butyrolactone, a preparation method thereof and a continuous preparation method of α-acetyl-γ-butyrolactone. BACKGROUND

[0002] α-acetyl-γ-butyrolactone (ABL), also known as 2-acetyl-γ-butyrolactone, is an important organic chemical raw material, which is an intermediate for the preparation of chlorophyll, and can also be used in the pharmaceutical industry to manufacture anti-angina drugs, is a raw material for the preparation of vitamin B1, and can also be used to synthesize 3,4-disubstituted pyridine and 5-(β-hydroxyethyl)-4-methylthiazole, antipsychotic drug risperidone and fungicide prothioconazole, and is widely used.

[0003] The traditional method for preparing ABL mainly relies on the use of metallic sodium or sodium alkoxide, which is subjected to Claisen condensation reaction with γ-butyrolactone. Although this method can achieve the synthesis of the target compound, it has significant defects in actual operation. Metallic sodium and sodium alkoxide are highly active substances, which will react violently when they come into contact with water or air. This not only increases the safety hazards in the production process, but also may cause equipment damage and environmental damage. In addition, the process using metallic sodium or sodium alkoxide usually involves a complex post-treatment process, especially in removing by-products and unreacted excess reagents, which often requires the consumption of a large amount of acid, thereby generating a large amount of acidic wastewater and solid waste, which not only increases the production cost, but also causes a burden to the environment.

[0004] At the same time, the batch reactor also has limitations in the preparation of ABL. This reaction mode is difficult to effectively control the reaction temperature and pressure, especially in the case of handling a large amount of reactants, heat dissipation becomes a big problem. Since the Claisen condensation reaction is exothermic, it is often difficult for the batch reactor to balance between high conversion rate and selectivity. In addition, the reaction time is long, the product yield is low, and due to the fluctuation of reaction conditions, the product quality is unstable, which limits the application of batch reactors in large-scale industrial production.

[0005] Currently, the main challenge of continuous preparation of ABL is to develop a catalyst system suitable for continuous operation. The ideal catalyst should have high activity, high selectivity and long service life, which can promote the Claisen condensation reaction under mild conditions, while avoiding the use of flammable and explosive metallic sodium or sodium alkoxide. In addition, the design of continuous reactor also needs to solve the complex problems of material flow, temperature control and pressure regulation, to ensure the continuity and stability of the reaction.

[0006] Therefore, how to provide a catalyst with high activity, high selectivity and long lifespan, and achieve continuous Claisen condensation reaction under mild conditions to obtain α-acetyl-γ-butyrolactone with high purity, without using metallic sodium or sodium alkoxide, is one of the important technical problems that need to be solved in this field. Summary of the Invention

[0007] The main objective of this invention is to provide a catalyst for the continuous preparation of α-acetyl-γ-butyrolactone, its preparation method, and the continuous preparation method of α-acetyl-γ-butyrolactone, so as to solve the problem that it is difficult to avoid the use of sodium metal or sodium alkoxide when synthesizing α-acetyl-γ-butyrolactone by Claisen condensation reaction in the prior art. At the same time, it solves the problems that the catalysts used for continuous Claisen condensation reaction in the prior art have low activity, low selectivity, short lifetime, and low purity of the obtained α-acetyl-γ-butyrolactone product.

[0008] To achieve the above objectives, a first aspect of the present invention provides a method for preparing a catalyst for the continuous preparation of α-acetyl-γ-butyrolactone, comprising: step S1, impregnating a support in a first solution containing a magnesium source to obtain a first product; step S2, impregnating the first product in a second solution containing a sodium source and a potassium source to obtain a second product; calcining the second product to obtain a third product; step S3, impregnating the third product in a third solution containing a cesium source and subjecting it to a first stirring treatment to obtain a fourth product; and step S4, impregnating the fourth product in a fourth solution containing Na3AlF6 and subjecting it to a second stirring treatment to obtain a catalyst for the continuous preparation of α-acetyl-γ-butyrolactone.

[0009] Furthermore, in step S1, the particle size of the carrier is 100-200 mesh, and the specific surface area is 200 m². 2 / g~300m 2 / g, and the support is selected from one or more of γ-Al2O3, magnesium oxide and silicon dioxide; and / or, in the first solution, the molar concentration of the magnesium source is 0.1mol / L to 1mol / L; and / or, the molar ratio of the support to the magnesium source is 1:(1 to 4); preferably, the magnesium source is selected from one or more of magnesium sulfate, magnesium carbonate and magnesium nitrate.

[0010] Further, in step S2, the molar concentration of the sodium source and the potassium source in the second solution is independently 0.1 mol / L-1 mol / L; and / or, the weight ratio of the sodium source to the potassium source in the second solution is (4-6):1; and / or, the holding temperature of the calcination treatment is 400°C-600°C, and the time is 4h-6h; the calcination treatment is carried out in a protective atmosphere, and the protective atmosphere is nitrogen and / or argon; preferably, the calcination treatment comprises sequentially: heating to 200±20°C at 5°C / min-10°C / min and holding for 0.5h-1h; heating to 400±20°C at 3°C / min-6°C / min and holding for 0.5h-1h; heating to 550°C-600°C at 1°C / min-3°C / min and holding for 2h-4h; more preferably, the sodium source is selected from one or more of a sulfate of sodium, a carbonate of sodium, and a nitrate of sodium; and / or, the potassium source is selected from one or more of a sulfate of sodium, a carbonate of potassium, and a nitrate of potassium.

[0011] Further, in step S3, the molar concentration of the cesium source in the third solution is 0.1 mol / L-1 mol / L; and / or, the time of the first stirring treatment is 1h-2h, and the first stirring treatment is carried out at 70°C-100°C; preferably, the cesium source is selected from one or more of a carbonate of cesium and a nitrate of cesium.

[0012] Further, in step S4, the molar concentration of Na3AlF6 in the fourth solution is 0.01 mol / L-0.1 mol / L; and / or, the time of the second stirring treatment is 2h-4h, and the second stirring treatment is carried out at 25±2°C; and / or, step S4 comprises: immersing the fourth product in the fourth solution containing Na3AlF6, and carrying out the second stirring treatment to obtain a fifth product, and the fifth product is subjected to a calcination treatment to obtain the catalyst for continuously preparing α-acetyl-γ-butyrolactone; preferably, the holding temperature of the calcination treatment is 300°C-550°C, and the time is 4h-8h.

[0013] Further, in step S4, the calcination treatment comprises sequentially: heating to 300±20°C at 1°C / min-5°C / min and holding for 1h-2h; heating to 500°C-550°C at 3°C / min-8°C / min and holding for 2h-4h.

[0014] The second aspect of the present application provides a catalyst for continuous preparation of alpha-acetyl-gamma-butyrolactone, which is prepared by the method for preparing the catalyst for continuous preparation of alpha-acetyl-gamma-butyrolactone described above; the catalyst for continuous preparation of alpha-acetyl-gamma-butyrolactone comprises cesium and fluorine, and the content of cesium is 1.0% to 7.0% and the content of fluorine is 0.8% to 2.5% based on the total weight of the catalyst for continuous preparation of alpha-acetyl-gamma-butyrolactone being 100%; preferably, the specific surface area of the catalyst for continuous preparation of alpha-acetyl-gamma-butyrolactone is 150 m 2 / g to 400 m 2 / g, and the mesopore size is 4 nm to 10 nm.

[0015] The third aspect of the present application provides a method for continuous preparation of alpha-acetyl-gamma-butyrolactone, which comprises: Claisen condensation of gamma-butyrolactone and acetic ester under the action of a catalyst to generate alpha-acetyl-gamma-butyrolactone; the catalyst is the catalyst for continuous preparation of alpha-acetyl-gamma-butyrolactone described above.

[0016] Further, the method for continuous preparation of alpha-acetyl-gamma-butyrolactone comprises: step A, loading the catalyst for continuous preparation of alpha-acetyl-gamma-butyrolactone into two reactors connected in series; step B, sequentially passing gamma-butyrolactone and acetic ester through the reactors to generate a reaction liquid through first condensation and second condensation; step C, mixing the reaction liquid with phosphoric acid to obtain alpha-acetyl-gamma-butyrolactone; preferably, the molar ratio of acetic ester to gamma-butyrolactone is (1.05 to 1.15): 1; more preferably, the acetic ester is selected from one or more of methyl acetate, ethyl acetate and butyl acetate.

[0017] Further, the first condensation is carried out under the conditions of a temperature of 160°C to 180°C, a pressure of 0.1 MPa to 2.5 MPa, and a space velocity of 0.3 h -1 to 35 h -1 ; and / or, the second condensation is carried out under the conditions of a temperature of 200°C to 220°C, a pressure of 0.1 MPa to 2.5 MPa, and a space velocity of 0.3 h -1 to 35 h -1 ; preferably, step C further comprises adding phosphoric acid to the reaction liquid until the pH value of the reaction liquid is 6 to 7 to obtain alpha-acetyl-gamma-butyrolactone.

[0018] By the technical scheme of the present application, the cesium-magnesium-aluminum composite solid base catalyst with a high-activity interface is constructed by modifying the carrier with cesium-magnesium, which can significantly improve the selectivity and conversion rate of the Claisen condensation reaction for preparing alpha-acetyl-gamma-butyrolactone, effectively inhibit the occurrence of side reactions, reduce the impurity content of the product, and thus improve the product purity and yield. In the continuous preparation process of alpha-acetyl-gamma-butyrolactone, the use of the catalyst can completely avoid the use of flammable and explosive sodium metal or sodium alcoholate solution, and eliminate the risk of dust explosion. At the same time, a large amount of acid does not need to be consumed to precipitate sodium salt, greatly reducing the amount of final three wastes. DETAILED DESCRIPTION

[0019] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail below with reference to the embodiments.

[0020] As described in the background, in the prior art, when alpha-acetyl-gamma-butyrolactone is synthesized by the Claisen condensation reaction, it is difficult to avoid the use of sodium metal or sodium alcoholate. At the same time, the catalyst for the continuous Claisen condensation reaction in the prior art has the problems of low activity, low selectivity, and short service life, and the prepared alpha-acetyl-gamma-butyrolactone product has the problem of low purity. In order to solve the above technical problems, the first aspect of the present application provides a preparation method of a catalyst for continuous preparation of alpha-acetyl-gamma-butyrolactone, comprising: step S1, immersing a carrier in a first solution containing a magnesium source to obtain a first product; step S2, immersing the first product in a second solution containing a sodium source and a potassium source to obtain a second product; the second product is treated by calcination to obtain a third product; step S3, immersing the third product in a third solution containing a cesium source, and treating by first stirring to obtain a fourth product; step S4, immersing the fourth product in a fourth solution containing Na3AlF6, and treating by second stirring to obtain a catalyst for continuous preparation of alpha-acetyl-gamma-butyrolactone (hereinafter referred to as catalyst).

[0021] The present application constructs a cesium-magnesium-aluminum composite solid base catalyst with a high-activity interface by modifying the carrier with cesium-magnesium, which can significantly improve the selectivity and conversion rate of the Claisen condensation reaction for preparing alpha-acetyl-gamma-butyrolactone, effectively inhibit the occurrence of side reactions, reduce the impurity content of the product, and thus improve the product purity and yield.

[0022] Specifically, in the prepared catalyst system, the introduction of magnesium can create a high specific surface area and porosity, thereby forming a composite structure with the support and increasing the structural stability and mechanical strength of the catalyst support. Magnesium oxide (MgO) itself has moderate basicity, which complements the strong basicity of cesium. Magnesium may optimize catalytic activity by stabilizing the local environment of cesium active sites (e.g., reducing the aggregation of basic sites). The introduction of cesium may modulate the electronic structure of the support surface through electronic interactions, enhancing the adsorption capacity for reactants (such as γ-butyrolactone) while promoting the stability of intermediates (such as enol anions). Na3AlF6 (cryolite), upon dissolving in water, releases F-, which reacts with Al in the support. 3+ and Mg 2+ This forms fluoroaluminates (such as NaAlF6) or fluoromagnesates (such as MgF2). These fluorides can coat the support surface, reducing strong acid sites (such as...). Acid sites are added to inhibit side reactions (such as polymerization or cracking). The synergistic effect of cesium and magnesium enhances catalytic activity through improved support stability and optimization of basic sites, while Na3AlF6 inhibits side reactions and improves thermal stability through surface modification and structural regulation. The combination of these three elements forms a highly active and selective Na-K-CsF / MgO-supported composite solid base catalyst.

[0023] In the continuous preparation of α-acetyl-γ-butyrolactone, the use of this catalyst completely avoids flammable and explosive sodium metal or sodium alkoxide solutions, eliminating the risk of dust explosions. Simultaneously, it eliminates the need for large amounts of acid to precipitate sodium salts, significantly reducing the amount of final waste.

[0024] In step S1: To provide more active sites and improve compatibility with active elements, thereby further enhancing the activity of the obtained catalyst, the preferred particle size of the support is 100-200 mesh, and the specific surface area is 200 m². 2 / g~300m 2 / g, and the support is selected from one or more of γ-Al2O3, magnesium oxide, and silicon dioxide. In order to form a more uniform magnesium distribution during the catalyst preparation process, thereby significantly optimizing the porosity and specific surface area of ​​the obtained catalyst, enhancing the adsorption capacity of reactant molecules, and thus improving the catalytic effect, in the first solution, preferably: the molar concentration of the magnesium source is 0.1mol / L to 1mol / L; and / or, the molar ratio of the support to the magnesium source is 1:(1 to 4).

[0025] In the second solution of step S2, preferably, the molar concentrations of the sodium source and the potassium source are each independently 0.1 mol / L to 1 mol / L; and / or, the weight ratio of the sodium source to the potassium source in the second solution is (4-6):1. In the preparation method provided by this invention, the synergistic effect of sodium and potassium is mainly reflected in:

[0026] Firstly, the Lewis acid (L acid) and Bronsted acid (B acid) sites exist on the surface of γ-Al2O3 support. These strong acid sites can catalyze some side reactions, such as excessive condensation, carbon deposition, and even the cracking of reactants. The presence of sodium and potassium can finely adjust and optimize the acid-base distribution on the surface of the catalyst, thereby inhibiting side reactions.

[0027] Secondly, the multifunctional active sites are constructed in cooperation with other additives (Cs, F, Mg). The F- introduced from Na3AlF6 is a strong electron-withdrawing group, while Na / K / Cs are electron-donating groups. The combination of this "push-pull electron" effect can create special active sites with uneven electron density on the surface of the catalyst, greatly promoting the separation and transfer of charges, and more significantly improving the catalytic efficiency.

[0028] Thirdly, the structural stability and electronic regulation ability of the catalyst are further enhanced. Since sodium and potassium are both electron-donating additives, the electrons they provide can affect the electron cloud density of adjacent active centers (which can be Cs + , Mg 2+ , or specific fluorine-oxygen sites). This electronic modulation can change the adsorption strength and mode of reactant molecules (such as γ-butyrolactone and ethyl acetate) on the surface of the catalyst, making it more conducive to the formation of target products, while also more effectively inhibiting side reaction pathways.

[0029] Based on this, the preferred concentrations and weight ratios mentioned above can further promote the uniform distribution of sodium and potassium ions on the surface of the obtained catalyst, reducing the plugging of catalyst active sites caused by excessive local concentration, while also not being able to provide enough active sites due to excessively low concentration. The synergistic effect of potassium and sodium in the preferred weight ratio not only improves the overall activity of the obtained catalyst, but also makes the reaction conditions more mild, which is conducive to the more stable operation of the continuous reaction system.

[0030] In the process of forming the composite carrier, in order to promote the deeper combination of the magnesium source and the carrier, form a more stable magnesium oxide structure, and further enhance the thermal stability of the obtained catalyst, prolong its service life, the holding temperature of the calcination treatment is preferably 400-600°C, and the time is 4-6h. On this basis, the inventors further prefer that the calcination treatment comprises the following steps in sequence: heating to 200±20°C at a rate of 5-10°C / min and holding for 0.5-1h; heating to 400±20°C at a rate of 3-6°C / min and holding for 0.5-1h; and heating to 550-600°C at a rate of 1-3°C / min and holding for 2-4h. This preferred scheme comprises stepwise heating and holding at three temperature stages, which is more conducive to the structure construction of the catalyst and the formation of active sites. First, the low-temperature treatment at a heating rate of 5-10°C / min can more effectively remove the surface-adsorbed water and impurities; then, holding at a higher temperature at a heating rate of 3-6°C / min is helpful to promote the deep combination of magnesium, sodium and potassium elements with the carrier, and form a more stable composite oxide structure. Finally, holding at the highest temperature at a heating rate of 1-3°C / min further consolidates the structure of the catalyst and optimizes the distribution of active sites. Ultimately, the obtained catalyst has higher activity, higher stability and longer life in a continuous reaction system.

[0031] In practical applications, in order to reduce the introduction of impurities, the calcination treatment is preferably carried out in a protective atmosphere, and the protective atmosphere is preferably nitrogen and / or argon

[0032] In the third solution of step S3, the molar concentration of the cesium source is preferably 0.1-1mol / L; and / or, the first stirring treatment is carried out for 1-2h at 70-100°C. The obtained molar concentration can promote the more uniform distribution of cesium elements; and the first stirring treatment under the above conditions not only promotes the more uniform impregnation of cesium elements, but also is beneficial to the further optimization of the internal structure of the catalyst, thereby more significantly improving the diffusion of reactant molecules on the surface of the catalyst and the reaction efficiency.

[0033] In the fourth solution of step S4, the molar concentration of Na3AlF6 is preferably 0.01-0.1mol / L; and / or, the second stirring treatment is carried out for 2-4h at 25±2°C. The above molar concentration of Na3AlF6 promotes the more uniform distribution of F elements, and reduces the damage to the pore structure of the catalyst and the reduction of active sites caused by excessive concentration. The conditions of the second stirring treatment are beneficial to the more sufficient combination of Na3AlF6 and the catalyst precursor.

[0034] In several typical embodiments, step S4 comprises: immersing the fourth product in a fourth solution containing Na3AlF6, and treating the fourth solution with second stirring to obtain a fifth product, and treating the fifth product with calcination to obtain the catalyst for continuously preparing α-acetyl-γ-butyrolactone. In this process, the holding temperature of the calcination treatment is preferably 300-550°C, and the time is 4-8h, so as to further stabilize the structure of the catalyst, and promote the deeper combination of the F element, and form more efficient and stable catalytic sites.

[0035] Based on the conditions of the calcination treatment, the further preferred calcination treatment in step S4 comprises: sequentially raising the temperature to 300±20°C at a rate of 1-5°C / min and holding for 1-2h; and raising the temperature to 500-550°C at a rate of 3-8°C / min and holding for 2-4h. In this preferred scheme, the staged calcination treatment can further optimize the structure and active sites of the catalyst, and promote it to exhibit higher stability in the continuous reaction system. The preliminary calcination at a lower temperature with a raising rate of 1-5°C / min can more effectively remove the adsorbed water and organic impurities, and create a cleaner reaction environment for the subsequent high-temperature treatment. The raising rate of the subsequent high-temperature holding process is preferably 3-8°C / min, which further promotes the deeper combination of the Cs, Mg and Al elements, forms a more stable composite oxide structure, and finally enhances the thermal stability and catalytic activity of the obtained catalyst.

[0036] In practical applications, the first solution, the second solution, the third solution and the fourth solution are all aqueous solutions. In addition, the immersion in each step is performed by the equal-volume immersion method. In each solution, the magnesium source is selected from one or more of a magnesium sulfate, a magnesium carbonate and a magnesium nitrate; and / or, the sodium source is selected from one or more of a sodium sulfate, a sodium carbonate and a sodium nitrate; and / or, the potassium source is selected from one or more of a potassium sulfate, a potassium carbonate and a potassium nitrate; and / or, the cesium source is selected from one or more of a cesium carbonate and a cesium nitrate.

[0037] The second aspect of the present application provides a catalyst for continuously preparing α-acetyl-γ-butyrolactone, which is obtained by the above-mentioned method for continuously preparing a catalyst for α-acetyl-γ-butyrolactone. The catalyst for continuously preparing α-acetyl-γ-butyrolactone comprises cesium and fluorine elements, and the content of the cesium element is 1.0-7.0% and the content of the fluorine element is 0.8-2.5% based on 100% of the total weight of the catalyst for continuously preparing α-acetyl-γ-butyrolactone.

[0038] The continuous preparation of α-acetyl-γ-butyrolactone catalyst prepared by the above method, due to the uniform distribution of elements and synergistic cooperation, the best balance of catalyst activity, selectivity and stability, so in the continuous reaction system, effectively promote the Claisen condensation reaction of γ-butyrolactone and acetic acid ester, significantly improve the yield and purity of α-acetyl-γ-butyrolactone, reduce the energy consumption, simplify the post-processing process, realize the efficient, environmental protection of industrial production. In the continuous preparation of α-acetyl-γ-butyrolactone catalyst obtained, the content of cesium element is controlled in 1.0%~7.0% (preferably 2.0%~5.0%, more preferably 2.0%~2.5%), this proportion ensures that the catalyst surface has enough basic sites, while avoiding the side reaction caused by excessive cesium and the blockage of the active site of the catalyst. The content of fluorine element is set to 0.8%~2.5% (preferably 1.0%~2.0%, more preferably 1.2%~1.6%), which helps to improve the thermal stability and anti-poisoning ability of the catalyst, and optimizes the porosity of the catalyst, enhances the diffusion and adsorption capacity of the reactant molecules.

[0039] In several preferred embodiments, the specific surface area of the continuous preparation of α-acetyl-γ-butyrolactone catalyst is 150m 2 / g~400m 2 / g, the mesopore size is 4nm~10nm.

[0040] The third aspect of the application provides a continuous preparation method of α-acetyl-γ-butyrolactone, which comprises: under the action of a catalyst, γ-butyrolactone and acetic acid ester undergo Claisen condensation reaction to generate α-acetyl-γ-butyrolactone; the catalyst is the above-mentioned continuous preparation of α-acetyl-γ-butyrolactone catalyst. In the process of preparing α-acetyl-γ-butyrolactone by γ-butyrolactone Claisen condensation reaction, by using the catalyst provided by the application, the Claisen condensation reaction can be efficiently carried out in the continuous reactor. The efficiency of the catalyst provided by the application lies in its special design, which can promote the effective activation of the reactant molecules, reduce the reaction activation energy, accelerate the reaction process, and effectively inhibit the side reaction and reduce the generation of by-products. Especially, when the catalyst provided by the application is used, in the reaction system of preparing α-acetyl-γ-butyrolactone by γ-butyrolactone Claisen condensation reaction, the use of metallic sodium and sodium alcoholate can be completely avoided, thereby greatly improving the safety and environmental protection of the synthesis reaction.

[0041] In practical applications, the continuous preparation method of α-acetyl-γ-butyrolactone comprises: step A, filling the catalyst for continuous preparation of α-acetyl-γ-butyrolactone into two reactors in series; step B, sequentially passing γ-butyrolactone and acetic acid ester through the reactors, and sequentially performing first condensation and second condensation to obtain a reaction liquid; and step C, mixing the reaction liquid with phosphoric acid to obtain α-acetyl-γ-butyrolactone. In this preferred scheme, by filling the catalyst into two reactors in series, the γ-butyrolactone reactant can be more fully contacted with the active sites of the catalyst, and the Claisen condensation reaction is more efficiently performed. In the first condensation stage, γ-butyrolactone reacts with acetic acid ester to generate a preliminary product, and in the second condensation stage, the product is further converted and optimized, thereby more significantly improving the purity and yield of the target product.

[0042] In the above continuous preparation process, the principle of two-stage reactor staged reaction is as follows:

[0043] First, the first-stage reactor: at a lower temperature and medium pressure, it focuses on starting the reaction, generating a key intermediate with high selectivity, and protecting the catalyst system. Reducing the occurrence of excessive condensation or decomposition reactions of high-concentration raw materials in the early stage improves selectivity. Second, the second-stage reactor: at a higher temperature and high pressure, the higher pressure increases the concentration of the reactants, which helps to improve the reaction rate according to chemical reaction kinetics. This stage reactor mainly focuses on completing the reaction, pursuing high conversion, and efficiently generating the final target product.

[0044] The design of the above multiple reactors in series makes the flow pattern of the entire system closer to that of a plug flow reactor. This means that the material passes through the reactors in sequence, the residence time distribution is more uniform, and the mixing (back mixing) of the front and rear materials is reduced, which can avoid the long-term mixing of the generated intermediate or product with high-concentration raw materials, thereby reducing the by-products generated by excessive reaction and more significantly improving the selectivity.

[0045] In addition, the molar ratio of acetic acid ester to γ-butyrolactone is preferably (1.05-1.15):1, so as to more effectively improve the selectivity and yield of the reaction, and promote the reaction system to exhibit more stability and promote more effective use of the active sites of the catalyst. Specifically, the acetic acid ester can be selected from one or more of methyl acetate, ethyl acetate, and butyl acetate.

[0046] In several typical embodiments, the conditions for the first condensation are: temperature 160-180°C, pressure 0.1-2.5 MPa, space velocity 0.3-35 h -1 -1 ​The above-mentioned first condensation conditions are preferred to enable the Claisen condensation reaction to be carried out under mild conditions. The preferred temperature and pressure of 160-180°C and 0.1-2.5 MPa can promote more effective activation of the reactants, reduce the reaction activation energy, increase the reaction rate, and better maintain the activity and stability of the catalyst, and reduce the sintering of the active sites of the catalyst at high temperature and the increase of side reactions caused by excessive pressure. The space velocity of 0.3-35 h -1 -1 The space velocity promotes more sufficient contact between the reactants and the catalyst, further improving the conversion rate and selectivity of the reaction. In another typical embodiment, the second condensation conditions are as follows: temperature 200-220°C, pressure 0.1-2.5 MPa, and space velocity 0.3-35 h -1 -1 The above-mentioned second condensation conditions can more effectively accelerate the reaction process and deep conversion, thereby further optimizing the purity and yield of the product of α-acetyl-γ-butyrolactone.

[0047] In practical applications, it is preferred that step C further comprises adding phosphoric acid to the reaction solution until the pH value of the reaction solution is 6-7 to obtain α-acetyl-γ-butyrolactone. That is, by using the catalyst system provided by the present application, after the product is finally obtained, the product can be separated by only neutralizing the reaction solution, without further operation, thereby greatly reducing the reaction risk, reaction complexity, and reaction energy consumption.

[0048] The present application will be further described in detail below in conjunction with specific examples, which should not be construed as limiting the scope of the present application.

[0049] Unless otherwise defined, all the professional terms used herein have the same meaning as generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific examples, and are not intended to limit the protection scope of the present application.

[0050] Example 1

[0051] Preparation of a catalyst for continuous preparation of α-acetyl-γ-butyrolactone:

[0052] ​​First, preparation of each aqueous solution: 32.4 g of Mg(N03)2was dissolved in 438.0 g of deionized water to obtain a magnesium salt aqueous solution (0.5 mol / L) under magnetic stirring, 20.0 g of NaN03was dissolved in 118.0 g of deionized water to obtain a sodium salt aqueous solution (0.5 mol / L), 4.0 g of KN03was dissolved in 20.0 g of deionized water to obtain a potassium salt aqueous solution (0.5 mol / L), 3.0 g of Na3AlF6was dissolved in 600 g of deionized water to obtain a Na3AlF6aqueous solution (0.024 mol / L), and 3.6 g of CsN03was dissolved in 9.2 g of deionized water to obtain a CsN03aqueous solution (0.5 mol / L).

[0053] (1) Preparation of the carrier: 70.0 g of γ-Al203(100-200 mesh, specific surface area 200-300 m2 / g) was mixed with the prepared magnesium salt aqueous solution by equal-volume impregnation (i.e., the molar ratio of the carrier to the magnesium source was 3.13:1), and after standing for 12 hours, a first product was obtained by filtration. 2

[0054] (2) Subsequently, the sodium salt aqueous solution and the potassium salt aqueous solution were mixed by equal-volume impregnation, and the first product was impregnated therein and aged. After the aging was completed, the second product was obtained by washing, filtering, and drying at 90°C for 4 h. Subsequently, a staged temperature increase reaction was performed under a nitrogen atmosphere. In the first stage, the temperature was increased from room temperature to 200°C at a rate of 5°C / min, and the holding time was 1 h; in the second stage, the temperature was increased from 200°C to 400°C at a rate of 3°C / min, and the holding time was 1 h; and in the third stage, the temperature was increased from 400°C to 580°C at a rate of 2°C / min, and the holding time was 4 h, to obtain a shaped carrier, i.e., a third product.

[0055] (3) Doping of the aid: the prepared aqueous solution containing cesium elements was mixed with the third product, and stirring was performed at 80°C for 2 h. After the stirring was completed, the fourth product was obtained by washing and filtering.

[0056] (4) Subsequently, the obtained fourth product solid was mixed with the prepared Na3AlF6aqueous solution, and stirring was performed at room temperature (25±2°C) for 2 h. After the stirring was completed, the fifth product was obtained by washing and filtering. The obtained fifth product solid was subjected to a continuous temperature increase method, in which the temperature was increased from room temperature to 300°C at a rate of 1°C / min, and the holding time was 1 h, then the temperature was increased to 550°C at a rate of 3°C / min, and the holding time was 4 h, and finally the temperature in the furnace was naturally cooled to below 200°C, to finally obtain a Na-K-CsF / MgO.Al203catalyst doped with rare earth elements, i.e., a continuously prepared catalyst for α-acetyl-γ-butyrolactone (in which the content of cesium elements was 2.36 wt%, and the content of fluorine elements was 1.57 wt%).

[0057] ​The specific surface area of the catalyst for continuous preparation of α-acetyl-γ-butyrolactone obtained is 350 m 2 / g, and the mesopore size is 6 nm.

[0058] A method for continuous preparation of α-acetyl-γ-butyrolactone:

[0059] (A) The obtained 104 g of Na-K-CsF / MgO·Al2O3 catalyst is equally filled into a first-stage and a second-stage reactor in series (52 g of solid catalyst is filled into each stage of reactor).

[0060] (B) The temperature of the first-stage reactor is 160-180 ℃, the pressure is 1.5 MPa, and the space velocity is 20.38 h -1 -1; the temperature of the second-stage reactor is 200-220 ℃, the pressure is 2.0 MPa, and the space velocity is 20.38 h -1 -1. γ-Butyrolactone and ethyl acetate are respectively fed into a preheater at a flow rate of 500 g / h (5.81 mol / h) and 560 g / h (6.36 mol / h) to heat to a reaction temperature of 160 ℃, and then sequentially enter the first-stage and second-stage reactors for reaction (the molar ratio of γ-butyrolactone to ethyl acetate is 1:1.09).

[0061] (C) After preliminary cooling, a certain amount of phosphoric acid is added to the obtained reaction solution to neutralize the pH to 6-7, and the target product α-acetyl-γ-butyrolactone (purity > 99.5%) is obtained by rectification purification, wherein the reaction results are shown in Table 1.

[0062] Example 2

[0063] Preparation of a catalyst for continuous preparation of α-acetyl-γ-butyrolactone:

[0064] The difference between this example and Example 1 is only that in the preparation of each aqueous solution, the weight of Mg(NO3)2 is changed from 32.4 g (0.22 mol) to 92.3 g (0.62 mol).

[0065] The specific surface area of the catalyst for continuous preparation of α-acetyl-γ-butyrolactone obtained is 320 m 2 / g, and the mesopore size is 8 nm.

[0066] A method for continuous preparation of α-acetyl-γ-butyrolactone: consistent with Example 1.

[0067] Example 3

[0068] Preparation of a catalyst for continuous preparation of α-acetyl-γ-butyrolactone:

[0069] The difference between this example and Example 1 is only that the weight of Mg(N03)2is changed from 32.4 g (0.22 mol) to 29.0 g (0.196 mol) during the preparation of each aqueous solution.

[0070] The specific surface area of the obtained catalyst for continuous preparation of α-acetyl-γ-butyrolactone is 360 m2 / g, and the mesopore size is 5 nm. 2

[0071] A method for continuous preparation of α-acetyl-γ-butyrolactone is consistent with Example 1.

[0072] Example 4

[0073] A method for continuous preparation of α-acetyl-γ-butyrolactone is consistent with Example 1.

[0074] The difference between this example and Example 1 is only that the weight of NaN03 is changed from 20.0 g (0.24 mol) to 24.0 g (0.28 mol) during the preparation of each aqueous solution.

[0075] The specific surface area of the obtained catalyst for continuous preparation of α-acetyl-γ-butyrolactone is 330 m2 / g, and the mesopore size is 7 nm. 2

[0076] A method for continuous preparation of α-acetyl-γ-butyrolactone is consistent with Example 1.

[0077] Example 5

[0078] A method for continuous preparation of α-acetyl-γ-butyrolactone is consistent with Example 1.

[0079] The difference between this example and Example 1 is only that the weight of NaN03 is changed from 20.0 g (0.24 mol) to 16.0 g (0.19 mol) during the preparation of each aqueous solution.

[0080] The specific surface area of the obtained catalyst for continuous preparation of α-acetyl-γ-butyrolactone is 370 m2 / g, and the mesopore size is 5 nm. 2

[0081] A method for continuous preparation of α-acetyl-γ-butyrolactone is consistent with Example 1.

[0082] Example 6

[0083] A method for continuous preparation of α-acetyl-γ-butyrolactone is consistent with Example 1.

[0084] ​​​The difference between this example and Example 1 is that in step (2), the calcination conditions are changed to:

[0085] First stage, room temperature to 200°C, heating rate 15°C / min, holding time 1 h; second stage 200°C to 400°C, heating rate 8°C / min, holding time 1 h; third stage 400°C to 600°C, heating rate 8°C / min, holding time 4 h.

[0086] The specific surface area of the catalyst for continuous production of α-acetyl-γ-butyrolactone obtained is 330 m 2 / g, and the mesopore size is 10 nm.

[0087] A method for continuous production of α-acetyl-γ-butyrolactone: consistent with Example 1.

[0088] Example 7

[0089] Preparation of a catalyst for continuous production of α-acetyl-γ-butyrolactone:

[0090] The difference between this example and Example 1 is that in step (2), the calcination conditions are changed to:

[0091] First stage, room temperature to 200°C, heating rate 3°C / min, holding time 1 h; second stage 200°C to 400°C, heating rate 2°C / min, holding time 1 h; and the third stage is not performed.

[0092] The specific surface area of the catalyst for continuous production of α-acetyl-γ-butyrolactone obtained is 400 m 2 / g, and the mesopore size is 5.5 nm.

[0093] A method for continuous production of α-acetyl-γ-butyrolactone: consistent with Example 1.

[0094] Example 8

[0095] Preparation of a catalyst for continuous production of α-acetyl-γ-butyrolactone:

[0096] The difference between this example and Example 1 is that in step (4), the calcination conditions are changed to:

[0097] Room temperature to 300°C, heating rate 8°C / min, holding time 1 h, then 10°C / min to 550°C, holding time 4 h.

[0098] The specific surface area of the catalyst for continuous production of α-acetyl-γ-butyrolactone obtained is 180 m 2 / g, and the mesopore size was 8 nm.

[0099] A continuous production method of α-acetyl-γ-butyrolactone was carried out in the same manner as in Example 1.

[0100] Example 9

[0101] Preparation of a catalyst for continuous production of α-acetyl-γ-butyrolactone:

[0102] This example differs from Example 1 only in that, in step (4), the calcination conditions were changed to:

[0103] The temperature was raised at a rate of 1°C / min to 300°C, held for 1 h, then raised at a rate of 1°C / min to 550°C, and held for 4 h.

[0104] The specific surface area of the obtained catalyst for continuous production of α-acetyl-γ-butyrolactone was 280 m 2 / g, and the mesopore size was 5.5 nm.

[0105] A continuous production method of α-acetyl-γ-butyrolactone was carried out in the same manner as in Example 1.

[0106] Example 10

[0107] Preparation of a catalyst for continuous production of α-acetyl-γ-butyrolactone:

[0108] A continuous production method of α-acetyl-γ-butyrolactone was carried out in the same manner as in Example 1.

[0109] This example differs from Example 1 only in that the flow rate of ethyl acetate was changed from 560 g / h (6.36 mol / h) to 665.1 g / h (7.6 mol / h).

[0110] At this time, the molar ratio of γ-butyrolactone to ethyl acetate was changed to 1:1.3 during the reaction.

[0111] Example 11

[0112] Preparation of a catalyst for continuous production of α-acetyl-γ-butyrolactone:

[0113] A continuous production method of α-acetyl-γ-butyrolactone was carried out in the same manner as in Example 1.

[0114] This example differs from Example 1 only in that the flow rate of ethyl acetate was changed from 560 g / h (6.36 mol / h) to 460.5 g / h (5.2 mol / h).

[0115] At this time, the molar ratio of γ-butyrolactone to ethyl acetate in the reaction was changed to 1 : 0.895.

[0116] Example 12

[0117] A preparation of a catalyst for continuous production of α-acetyl-γ-butyrolactone:

[0118] The difference between this example and Example 1 is only that the weight of Na3AlF6was changed from 3.0 g to 4.58 g in the preparation of each aqueous solution.

[0119] In this example, the proportion of fluorine in the final α-acetyl-γ-butyrolactone catalyst obtained was changed to 2.5 wt%.

[0120] The specific surface area of the continuous α-acetyl-γ-butyrolactone catalyst obtained was 260 m 2 / g, and the mesopore size was 4.5 nm.

[0121] A continuous production method of α-acetyl-γ-butyrolactone: consistent with Example 1.

[0122] Example 13

[0123] A preparation of a catalyst for continuous production of α-acetyl-γ-butyrolactone:

[0124] The difference between this example and Example 1 is only that the weight of Na3AlF6was changed from 3.0 g to 1.54 g in the preparation of each aqueous solution.

[0125] In this example, the proportion of fluorine in the final α-acetyl-γ-butyrolactone catalyst obtained was changed to 0.8 wt%. The specific surface area of the continuous α-acetyl-γ-butyrolactone catalyst obtained was 150 m 2 / g, and the mesopore size was 4.0 nm.

[0126] A continuous production method of α-acetyl-γ-butyrolactone: consistent with Example 1.

[0127] Example 14

[0128] A preparation of a catalyst for continuous production of α-acetyl-γ-butyrolactone:

[0129] The difference between this example and Example 1 is only that the weight of Na3AlF6was changed from 3.0 g to 1.54 g in the preparation of each aqueous solution.

[0130] In this example, the proportion of cesium element in the final α-acetyl-γ-butyrolactone catalyst is changed to 7.0 wt%. The specific surface area of the obtained continuous α-acetyl-γ-butyrolactone catalyst is 320 m 2 / g, and the mesopore size is 5.5 nm.

[0131] A continuous preparation method of α-acetyl-γ-butyrolactone is as follows: the same as that of Example 1.

[0132] Example 15

[0133] A preparation of a continuous α-acetyl-γ-butyrolactone catalyst is as follows: the same as that of Example 1.

[0134] The difference between this example and Example 1 is that the weight of CsNO3 is changed from 3.0 g to 1.5 g in the preparation of each aqueous solution.

[0135] In this example, the proportion of cesium element in the final α-acetyl-γ-butyrolactone catalyst is changed to 1.0 wt%. The specific surface area of the obtained continuous α-acetyl-γ-butyrolactone catalyst is 280 m 2 / g, and the mesopore size is 4.5 nm.

[0136] A continuous preparation method of α-acetyl-γ-butyrolactone is as follows: the same as that of Example 1.

[0137] Example 16

[0138] A preparation of a continuous α-acetyl-γ-butyrolactone catalyst is as follows: the same as that of Example 1.

[0139] A continuous preparation method of α-acetyl-γ-butyrolactone is as follows:

[0140] The difference between this example and Example 1 is that the temperature in the first-stage reactor is changed to 200-220°C.

[0141] Example 17

[0142] A preparation of a continuous α-acetyl-γ-butyrolactone catalyst is as follows: the same as that of Example 1.

[0143] A continuous preparation method of α-acetyl-γ-butyrolactone is as follows:

[0144] The difference between this example and Example 1 is that the temperature in the first-stage reactor is changed to 120-140°C.

[0145] Example 18

[0146] A catalyst for continuous production of α-acetyl-γ-butyrolactone was prepared in accordance with Example 1.

[0147] A method for continuous production of α-acetyl-γ-butyrolactone:

[0148] This example differs from Example 1 only in that the pressure in the first stage reactor was changed to 0 MPa to 0.1 MPa.

[0149] Example 19

[0150] A catalyst for continuous production of α-acetyl-γ-butyrolactone was prepared in accordance with Example 1.

[0151] A method for continuous production of α-acetyl-γ-butyrolactone:

[0152] This example differs from Example 1 only in that the pressure in the first stage reactor was changed to 0 MPa to 0.1 MPa.

[0153] Example 20

[0154] A catalyst for continuous production of α-acetyl-γ-butyrolactone was prepared in accordance with Example 1.

[0155] A method for continuous production of α-acetyl-γ-butyrolactone:

[0156] This example differs from Example 1 only in that the temperature in the second stage reactor was changed to 240°C to 260°C.

[0157] Example 21

[0158] A catalyst for continuous production of α-acetyl-γ-butyrolactone was prepared in accordance with Example 1.

[0159] A method for continuous production of α-acetyl-γ-butyrolactone:

[0160] This example differs from Example 1 only in that the temperature in the second stage reactor was changed to 160°C to 180°C.

[0161] Example 22

[0162] A catalyst for continuous production of α-acetyl-γ-butyrolactone was prepared in accordance with Example 1.

[0163] A method for continuous production of α-acetyl-γ-butyrolactone:

[0164] This example differs from Example 1 only in that the pressure in the second stage reactor was changed to 2.5 MPa to 3.5 MPa.

[0165] Example 23

[0166] Preparation of a catalyst for continuous production of α-acetyl-γ-butyrolactone: the same as in Example 1.

[0167] A method for continuous production of α-acetyl-γ-butyrolactone:

[0168] This example differs from Example 1 only in that the pressure in the second stage reactor is changed to 0 to 0.1 MPa.

[0169] Example 24

[0170] Preparation of a catalyst for continuous production of α-acetyl-γ-butyrolactone: the same as in Example 1.

[0171] A method for continuous production of α-acetyl-γ-butyrolactone:

[0172] This example differs from Example 1 only in that the first stage reactor is not provided and α-acetyl-γ-butyrolactone is obtained only by the second stage reactor.

[0173] Example 25

[0174] Preparation of a catalyst for continuous production of α-acetyl-γ-butyrolactone: the same as in Example 1.

[0175] A method for continuous production of α-acetyl-γ-butyrolactone:

[0176] This example differs from Example 1 only in that the second stage reactor is not provided and α-acetyl-γ-butyrolactone is obtained only by the first stage reactor.

[0177] Comparative Example 1

[0178] A method for continuous production of α-acetyl-γ-butyrolactone:

[0179] This example differs from Example 1 only in that no catalyst is loaded in the reactor.

[0180] Test Method

[0181] Specific surface area of the obtained catalyst: The specific surface area of the catalyst was determined using an autosorb iQ physisorption instrument. The instrument is based on the BET method (Brunauer-Emmett-Teller method) based on the multilayer adsorption theory, through the physical adsorption behavior of nitrogen at liquid nitrogen temperature (77.35 K) to calculate the specific surface area of the material. Install the sample tube → set the degassing temperature → start vacuuming → maintain until the pressure is stable → cool to room temperature → load the sample tube → inject liquid nitrogen → set the test parameters (pressure points, mode) → start the adsorption-desorption cycle → save the data. According to the determination data, the surface area data is calculated by the BET equation.

[0182] Mesopore size of the obtained catalyst: The specific surface area of the catalyst was determined using an autosorb iQ physisorption instrument. The sample was loaded into the sample tube, connected to the nitrogen source and pressure control system, and the adsorption and desorption data were obtained. From low relative pressure (P / P0=0.05) to 0.995, the adsorption amount was recorded; from high pressure (P / P0=0.995) to 0.05, the desorption amount was recorded, and the adsorption / desorption data were inputted, and the BJH model was selected. Set the pore size range, adjust the adsorption layer thickness formula (such as Halsey or Harkins-Jura equation, so as to obtain various data of the catalyst pore size distribution.

[0183] Conversion rate and selectivity of γ-butyrolactone: GC gas chromatography analyzer, gas chromatography (GC) is based on the difference in distribution between the stationary phase and the mobile phase to realize separation and quantitative analysis.

[0184] The sample is carried by the carrier gas (mobile phase, such as He, N2) into the chromatographic column, and the stationary phase (liquid or solid coating) in the column selectively adsorbs the components. Different components form separation due to the difference in distribution coefficient, and the components with high volatility flow out first. The retention time (RT) reflects the polarity, boiling point and other characteristics of the components. After the components enter the detector (such as FID, TCD), they are converted into electrical signals. The peak area or peak height is proportional to the component concentration, and the component content of the reactant is calculated by the standard curve method (external standard method / internal standard method) or normalization method. The content of each component in the reaction mixture is determined by sampling analysis after the reaction, and the conversion rate and selectivity of γ-butyrolactone are calculated, wherein:

[0185] Conversion rate = [1-(content of γ-butyrolactone)] / 1*100%

[0186] Selectivity = (content of α-acetyl-γ-butyrolactone) / (conversion rate of γ-butyrolactone)*100%

[0187] The content of α-acetyl-γ-butyrolactone, dimer, condensate and other impurities in the reaction product: GC gas chromatograph is used for analysis. The gas chromatography (GC) is based on the difference in partitioning between the stationary phase and the mobile phase to realize separation and quantitative analysis.

[0188] The sample is carried into the chromatographic column by the carrier gas (mobile phase, such as He, N2), the stationary phase (liquid or solid coating) in the column selectively adsorbs the components, and different components are separated due to the difference in partition coefficient. The components with high volatility flow out first, and the retention time (RT) reflects the polarity, boiling point and other characteristics of the components. After the components enter the detector (such as FID, TCD), they are converted into electrical signals. The peak area or peak height is proportional to the concentration of the components. The content of each component of the reactant is calculated by standard curve method (external standard method / internal standard method) or normalization method.

[0189] Lifetime of the catalyst: if the conversion rate suddenly decreases or decreases to below 90% during use, and there is no obvious improvement after regeneration, it is judged that the catalyst is invalid.

[0190] The above test results are shown in Table 1.

[0191] Table 1

[0192]

[0193] From the above description, it can be seen that the catalyst provided by the above-mentioned embodiments of the present application can complete the Claisen condensation reaction of γ-butyrolactone to obtain α-acetyl-γ-butyrolactone under relatively mild conditions. In particular, in Example 1, the content of α-acetyl-γ-butyrolactone in the product obtained is higher, the content of impurities is lower, and the service life of the catalyst is also longer compared with other embodiments. From Comparative Example 1, it can be seen that the conversion rate and selectivity of γ-butyrolactone in each embodiment of the present application are high, which indicates that the effect and method of preparing α-acetyl-γ-butyrolactone in the embodiments are better.

[0194] Specifically, in each embodiment, the catalyst preparation process of the present application is as follows:

[0195] Comparing Examples 2 and 3 with Example 1, it can be seen that by optimizing the amount of magnesium source added, a more uniform distribution of magnesium can be formed during the preparation of the catalyst, thereby more significantly optimizing the porosity and specific surface area of the obtained catalyst, enhancing the adsorption capacity of the reactant molecules, and further improving the catalytic effect.

[0196] Correspondingly, comparing Examples 4 and 5 with Example 1, it can be seen that when the amount of sodium source is optimized, it can promote better cooperation with K, and at the same time, promote more uniform distribution of sodium and potassium ions on the surface of the obtained catalyst, thereby improving the overall activity of the obtained catalyst.

[0197] Comparing Example 6, 7 with Example 1, it can be seen that by optimizing the calcination conditions in step S2, the magnesium source can be more deeply combined with the carrier to form a more stable magnesium oxide structure, thereby further enhancing the thermal stability of the obtained catalyst and prolonging its service life.

[0198] Comparing Example 8, 9 with Example 1, it can be seen that by optimizing the staged calcination conditions in step S4, the structure and active sites of the catalyst can be further optimized to enable it to exhibit higher stability in a continuous reaction system.

[0199] Comparing Example 12, 13 with Example 1, it can be seen that by optimizing the amount of Na3AlF6 added, the uniform distribution of F elements can be promoted, reducing the destruction of the catalyst's pore structure and the reduction of active sites caused by excessive concentration, and helping to improve the catalyst's thermal stability and resistance to poisoning, while optimizing the catalyst's porosity and enhancing the diffusion and adsorption capacity of reactant molecules, thereby further improving the service life and catalytic activity of the prepared catalyst.

[0200] Comparing Example 14, 15 with Example 1, it can be seen that by optimizing the amount of cesium source added, the uniform distribution of cesium elements can be more effectively promoted, strengthening its synergistic effect with other elements and the carrier. And by optimizing the amount of cesium added, the catalyst surface can have sufficient basic sites, while avoiding excessive cesium causing side reactions and blocking of the catalyst's active sites.

[0201] And for the process of obtaining α-acetyl-γ-butyrolactone through Claisen condensation of γ-butyrolactone:

[0202] Comparing Example 10, 11 with Example 1, it can be seen that by optimizing the feed flow rate of acetic ester monomers during the condensation reaction, and thereby adjusting the molar ratio of acetic esters to γ-butyrolactone, the selectivity and yield of the reaction can be more effectively improved, while enabling the reaction system to exhibit more stability and promoting more effective utilization of the catalyst's active sites.

[0203] Comparing Example 16 to 19 with Example 1, it can be seen that by optimizing the temperature and pressure conditions of the first-stage reactor, the reactants can be more effectively activated, the reaction activation energy can be reduced, the reaction rate can be increased, and the activity and stability of the catalyst can be better maintained, reducing the sintering of the catalyst's active sites at high temperatures and the increase in side reactions caused by excessive pressure.

[0204] Comparing Example 20 to 23 with Example 1, it can be seen that by optimizing the temperature and pressure conditions of the second-stage reactor, the reaction process and depth of conversion can be more effectively accelerated, thereby further optimizing the purity and yield of the product α-acetyl-γ-butyrolactone.

[0205] Comparing Example 24, 25 with Example 1, it can be seen that by setting two reactors in cooperation, the flow pattern of the whole system can be made closer to that of a plug flow reactor. This means that the materials pass through the reactors in turn, the residence time distribution is more uniform, the mixing (back mixing) of the materials before and after is reduced, the already generated intermediates or products can be prevented from mixing with the high concentration raw materials for a long time, thus reducing the by-products generated due to over-reaction, and more significantly improving the selectivity.

[0206] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application are used to distinguish similar objects, and do not necessarily have to be used to describe a specific order or sequence. It should be understood that the terms thus used can be interchanged under appropriate circumstances, so that the embodiments of the present application described herein can be implemented, for example, in an order other than that described herein.

[0207] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for the preparation of a catalyst for the continuous production of α-acetyl-γ-butyrolactone, characterized in that The application relates to a continuous preparation method of a catalyst for preparing alpha-acetyl-gamma-butyrolactone. The application relates to a continuous preparation method of a catalyst for preparing alpha-acetyl-gamma-butyrolactone. The application relates to a continuous preparation method of a catalyst for preparing alpha-acetyl-gamma-butyrolactone. The application relates to a continuous preparation method of a catalyst for preparing alpha-acetyl-gamma-butyrolactone. The application relates to a continuous preparation method of a catalyst for preparing alpha-acetyl-gamma-butyrolactone. The application relates to a continuous preparation method of a catalyst for preparing alpha-acetyl-gamma-butyrolactone.

2. The process for the preparation of catalysts for the continuous preparation of α-acetyl-γ-butyrolactone according to claim 1, characterized in that, The application relates to a continuous preparation method of a catalyst for preparing alpha-acetyl-gamma-butyrolactone. The particle size of the carrier is 100 mesh to 200 mesh, and the specific surface area is 200 m 2 / g to 300 m 2 / g, and the carrier is selected from one or more of γ-AI2O3, magnesium oxide, and silicon dioxide; and / or, The application relates to a continuous preparation method of a catalyst for preparing alpha-acetyl-gamma-butyrolactone. The application relates to a continuous preparation method of a catalyst for preparing alpha-acetyl-gamma-butyrolactone. The application relates to a continuous preparation method of a catalyst for preparing alpha-acetyl-gamma-butyrolactone.

3. The method for preparing a catalyst for the continuous production of α-acetyl-γ-butyrolactone according to claim 1 or 2, characterized in that, The application relates to a continuous preparation method of a catalyst for preparing alpha-acetyl-gamma-butyrolactone. The application relates to a continuous preparation method of a catalyst for preparing alpha-acetyl-gamma-butyrolactone. The application relates to a continuous preparation method of a catalyst for preparing alpha-acetyl-gamma-butyrolactone. The application relates to a continuous preparation method of a catalyst for preparing alpha-acetyl-gamma-butyrolactone. The application relates to a continuous preparation method of a catalyst for preparing alpha-acetyl-gamma-butyrolactone. The application relates to a continuous preparation method of a catalyst for preparing alpha-acetyl-gamma-butyrolactone. The application relates to a continuous preparation method of a catalyst for preparing alpha-acetyl-gamma-butyrolactone.

4. The process for the preparation of a catalyst for the continuous preparation of α-acetyl-γ-butyrolactone according to any one of claims 1 to 3, characterized in that, The application relates to a continuous preparation method of a catalyst for preparing alpha-acetyl-gamma-butyrolactone. The application relates to a continuous preparation method of a catalyst for preparing alpha-acetyl-gamma-butyrolactone. The application relates to a continuous preparation method of a catalyst for preparing alpha-acetyl-gamma-butyrolactone. The application relates to a continuous preparation method of a catalyst for preparing alpha-acetyl-gamma-butyrolactone.

5. The process for the preparation of a catalyst for the continuous preparation of α-acetyl-γ-butyrolactone according to any one of claims 1 to 4, characterized in that, The application relates to a continuous preparation method of a catalyst for preparing alpha-acetyl-gamma-butyrolactone. The application relates to a continuous preparation method of a catalyst for preparing alpha-acetyl-gamma-butyrolactone. The application relates to a continuous preparation method of a catalyst for preparing alpha-acetyl-gamma-butyrolactone. The application relates to a continuous preparation method of a catalyst for preparing alpha-acetyl-gamma-butyrolactone. The application relates to a continuous preparation method of a catalyst for preparing alpha-acetyl-gamma-butyrolactone. The application relates to a continuous preparation method of a catalyst for preparing alpha-acetyl-gamma-butyrolactone. 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The application relates to a continuous preparation method of a catalyst for preparing alpha-acetyl-gamma-butyrolactone. The application relates to a continuous preparation method of a catalyst for preparing alpha-acetyl-gamma-butyrolactone. The application relates to a continuous preparation method of a catalyst for preparing alpha-acetyl-gamma-butyrolactone. The application relates to a continuous preparation method of a catalyst for preparing alpha-acetyl-gamma-butyrolactone. The application relates to a continuous preparation method of a catalyst for preparing alpha-acetyl-gamma-butyrolactone. The application relates to a continuous preparation method of a catalyst for preparing alpha-acetyl-gamma-butyrolactone. The application relates to a continuous preparation method of a catalyst for preparing alpha-acetyl-gamma-butyrolactone. The application relates to a continuous preparation method of a catalyst for preparing alpha-acetyl-gamma-butyrolactone. The application relates to a continuous preparation method of a catalyst for preparing alpha-acetyl-gamma-butyrolactone. The application relates to a continuous preparation method of a catalyst for preparing alpha-acetyl-gamma-butyrolactone. The application relates to a continuous preparation method of a catalyst for preparing alpha-acetyl-gamma-butyrolactone. The application relates to a continuous preparation method of a catalyst for preparing alpha-acetyl-gamma-butyrolactone. The application relates to a continuous preparation method of a catalyst for preparing alpha-acetyl-gamma-butyrolactone. The application relates to a continuous preparation method of a catalyst for preparing alpha-acetyl-gamma-butyrolactone. The application relates to a continuous preparation method of a catalyst for preparing alpha-acetyl-gamma-butyrolactone. The application relates to a continuous preparation method of a catalyst for preparing alpha-acetyl-gamma-butyrolactone. The application relates to a continuous preparation method of a catalyst for preparing alpha-acetyl-gamma-butyrolactone. The application relates to a continuous preparation method of a catalyst for preparing alpha-acetyl-gamma-butyrolactone. The application relates to a continuous preparation method of a catalyst for preparing alpha-acetyl-gamma-butyrolactone. The application relates to a continuous preparation method of a catalyst for preparing alpha-acetyl-gamma-butyrolactone. The application relates to a continuous preparation method of a catalyst for preparing alpha-acetyl-gamma-butyrolactone. The application relates to a continuous preparation method of a catalyst for preparing alpha-acetyl-gamma-butyrolactone. The application relates to a continuous preparation method of a catalyst for preparing alpha-acetyl-gamma-butyrolactone. The application relates to a continuous preparation method of a catalyst for preparing alpha-acetyl-gamma-butyrolactone. The application relates to a continuous preparation method of a catalyst for preparing alpha-acetyl-gamma-butyrolactone. The application relates to a continuous preparation method of a catalyst for preparing alpha-acetyl-gamma-butyrolactone. The application relates to a continuous preparation method of a catalyst for preparing alpha-acetyl-gamma-butyrolactone. The application relates to a continuous preparation method of a catalyst for preparing alpha-acetyl-gamma-butyrolactone. The application relates to a continuous preparation method of a catalyst for preparing alpha-acetyl-gamma-butyrolactone. The application relates to a continuous preparation method of a catalyst for preparing alpha-acetyl-gamma-butyrolactone. The application relates to a continuous preparation method of a catalyst for preparing alpha-acetyl-gamma-butyrolactone. The application relates to a continuous preparation method of a catalyst for preparing alpha-acetyl-gamma-butyrolactone. The application relates to a continuous preparation method of a catalyst for preparing alpha-acetyl-gamma-butyrolactone. The application relates to a continuous preparation method of a catalyst for preparing alpha-acetyl-gamma-butyrolactone. The application relates to a continuous preparation method of a catalyst for preparing alpha-acetyl-gamma-butyrolactone. The application relates to a continuous preparation method of a catalyst for preparing alpha-acetyl-gamma-butyrolactone. The application relates to a continuous preparation method of a catalyst for preparing alpha-acetyl-gamma-butyrolactone. The application relates to a continuous preparation method of a catalyst for preparing alpha-acetyl-gamma-butyrolactone. The application relates to a continuous preparation method of a catalyst for preparing alpha-acetyl-gamma-butyrolactone. The application relates to a continuous preparation method of a catalyst for preparing alpha-acetyl-gamma-butyrolactone. The application relates to a continuous preparation method of a catalyst for preparing alpha-acetyl-gamma-butyrolactone. The application relates to a continuous preparation method of a catalyst for preparing alpha-acetyl-gamma-butyrolactone. The application relates to a continuous preparation method of a catalyst for preparing alpha-acetyl-gamma-butyrolactone. The application relates to a continuous preparation method of a catalyst for preparing alpha-acetyl-gamma-butyrolactone. The application relates to a continuous preparation method of a catalyst for preparing alpha-acetyl-gamma-butyrolactone. The application relates to a continuous preparation method of a catalyst for preparing alpha-acetyl-gamma-butyrolactone. The application relates to a continuous preparation method of a catalyst for preparing alpha-acetyl-gamma-butyrolactone. The application relates to a continuous preparation method of a catalyst for preparing alpha-acetyl-gamma-butyrolactone. The application relates to a continuous preparation method of a catalyst for preparing alpha-acetyl-gamma-butyrolactone. The application relates to a continuous preparation method of a catalyst for preparing alpha-acetyl-gamma-butyrolactone. The application relates to a continuous preparation method 6. The method of claim 5, wherein the catalyst is prepared continuously. The step S4 includes sequentially: heating to 300±20℃ at 1℃ / min-5℃ / min and keeping for 1h-2h; heating to 500-550℃ at 3℃ / min-8℃ / min and keeping for 2h-4h.

7. A catalyst for the continuous production of α-acetyl-γ-butyrolactone, characterized by, The continuous preparation method of the α-acetyl-γ-butyrolactone catalyst is prepared by the continuous preparation method of the α-acetyl-γ-butyrolactone catalyst according to any one of claims 1-6. The continuous preparation method of the α-acetyl-γ-butyrolactone catalyst includes cesium and fluorine elements, and the content of the cesium element is 1.0%-7.0% and the content of the fluorine element is 0.8%-2.5% based on 100% of the total weight of the continuous preparation method of the α-acetyl-γ-butyrolactone catalyst; Preferably, the specific surface area of the catalyst used for the continuous preparation of α-acetyl-γ-butyrolactone is between 150 m 2 / g and 400 m 2 / g, and the mesopore size is between 4 nm and 10 nm.

8. A continuous process for the preparation of an alpha-acetyl-gamma-butyrolactone, the continuous process for the preparation of an alpha-acetyl-gamma-butyrolactone comprising: The γ-butyrolactone and the acetic acid ester undergo a Claisen condensation reaction under the action of the catalyst to generate the α-acetyl-γ-butyrolactone; and the catalyst is the continuous preparation method of the α-acetyl-γ-butyrolactone catalyst according to claim 7.

9. The continuous process for the preparation of an alpha-acetyl-gamma-butyrolactone according to claim 8, characterized in that, The continuous preparation method of the α-acetyl-γ-butyrolactone includes: Step A, loading the continuous preparation method of the α-acetyl-γ-butyrolactone catalyst into two reactors in series; Step B, sequentially passing the γ-butyrolactone and the acetic acid ester through the reactors to generate a reaction liquid through first condensation and second condensation; Step C, mixing the reaction liquid with phosphoric acid to generate the α-acetyl-γ-butyrolactone; Preferably, the molar ratio of the acetic acid ester and the γ-butyrolactone is (1.05-1.15):1; More preferably, the acetic acid ester is selected from one or more of methyl acetate, ethyl acetate, and butyl acetate.

10. The continuous preparation method of the α-acetyl-γ-butyrolactone according to claim 9, wherein The first condensation is carried out at a temperature of 160°C to 180°C, a pressure of 0.1 MPa to 2.5 MPa, a space velocity of 0.3 h -1 to 35 h -1 ; and / or, The second condensation is carried out at a temperature of 200°C to 220°C, a pressure of 0.1 MPa to 2.5 MPa, a space velocity of 0.3 h -1 to 35 h -1 ; Preferably, the step C further includes adding the phosphoric acid to the reaction liquid until the pH value of the reaction liquid is 6-7 to generate the α-acetyl-γ-butyrolactone.

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