Molecular sieve adsorbent as well as preparation method and application method thereof

Abstract

The invention discloses a molecular sieve adsorbent as well as a preparation method and an application method thereof. The preparation method of the molecular sieve adsorbent comprises the following steps: 1) uniformly mixing a silicon source, an aluminum source and a sodium hydroxide aqueous solution, and then adding a template agent; the template agent is one or more of 1, 5 bis (N-methyl pyrrolidone) pentyl ammonium bromide, tetramethylammonium hydroxide and hexadecyl trimethyl ammonium bromide; 2) transferring the raw material mixture into a crystallization kettle, and carrying out crystallization reaction at 160-210 DEG C; 3) after the reaction is finished, filtering, washing, drying and roasting to obtain a molecular sieve precursor; and 4) soaking the molecular sieve precursor in an ammonium nitrate solution, and treating to obtain the molecular sieve adsorbent. The molecular sieve adsorbent with high selectivity on the coupling heavy components in the aromatic aldehyde acetal reaction liquid is prepared, and the separation of the coupling heavy components in the aromatic aldehyde acetal reaction liquid can be realized.

Description

Technical Field

[0001] The invention relates to a post-treatment method for electrochemical synthesis of aromatic aldehyde acetal reaction liquid, in particular to a molecular sieve adsorbent and a preparation method and an application method thereof. Background Art

[0002] Aromatic aldehydes are an important organic chemical raw material with large downstream market demand. They can be used as pharmaceutical intermediates, flavors and fragrances, sunscreen and other fields, and have good market prospects and economic benefits. Aromatic aldehydes are aldehyde compounds containing alkyl, alkoxy, aralkyl, nitrogen alkyl and other functional groups on the benzene ring. The synthesis methods are divided into chemical synthesis and electrochemical synthesis. Among them, the chemical synthesis method has harsh reaction conditions, low selectivity and greater safety risks.

[0003] The electrochemical method can obtain aromatic aldehyde acetals through direct electro-oxidation of aromatic hydrocarbons, and then obtain aromatic aldehyde products through hydrolysis. Compared with the chemical process, its reaction conditions are mild, selectivity is high, and there are fewer three wastes, and its competitive advantages are obvious. Among them, aromatic aldehyde acetals are generated by oxidation reaction of aromatic hydrocarbon raw materials in the electrolytic cell. The resulting reaction liquid mainly includes solvents, aromatic aldehyde acetals, unreacted aromatic hydrocarbons, coupling heavy components, etc. The electrolyte salts are sodium fluoride, potassium fluoride, potassium bromide, sodium bromide, etc., and the electrolyte needs to be recycled. The traditional process is to completely remove the reaction products, crystallize the electrolyte salts, and then filter them, and transfer the electrolyte salts and aromatic hydrocarbon raw materials to the electrolytic reaction system for recycling. In this process, the coupling heavy components cannot be completely removed, and they are continuously accumulated with the continuous circulation of the electrolyte, which leads to a decrease in current efficiency and a shortened electrode life; and there is a transfer of electrolytes, and there are many special operations.

[0004] In order to solve the above problems, electrolyte salts are usually discharged in large quantities to avoid the accumulation of impurities in the system, which increases the amount of solid waste and does not fundamentally solve the above problems. Therefore, a simple and effective treatment method is needed to separate the by-products and is easy to continuously industrialize. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a molecular sieve adsorbent and a preparation method and an application method thereof.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0007] A method for preparing a molecular sieve adsorbent comprises the following steps:

[0008] 1) uniformly mixing a silicon source, an aluminum source and a sodium hydroxide aqueous solution, and then adding a template agent; the template agent is one or more of 1,5-bis(N-methylpyrrolidone)pentyl ammonium bromide, tetramethyl ammonium hydroxide, and hexadecyl trimethyl ammonium bromide, preferably a mixture of 1,5-bis(N-methylpyrrolidone)pentyl ammonium bromide and optionally tetramethyl ammonium hydroxide and hexadecyl trimethyl ammonium bromide, and more preferably, 1,5-bis(N-methylpyrrolidone)pentyl ammonium bromide accounts for half or more of the total molar amount of the template agent in the mixture;

[0009] 2) transferring the raw material mixture to a crystallization kettle and performing a crystallization reaction at 160-210° C.;

[0010] 3) After the reaction is completed, filtering, washing, drying, and calcining to obtain a molecular sieve precursor;

[0011] 4) Immersing the molecular sieve precursor in an ammonium nitrate solution, and obtaining the molecular sieve adsorbent after treatment.

[0012] As some preferred examples of the present invention, in step 1), the molar ratio of the silicon source, the aluminum source, the sodium hydroxide, and the template agent is (30-70):1:(40-65):(4-17);

[0013] Preferably, the silicon source is silica sol;

[0014] Preferably, the aluminum source is one or both of aluminum isopropoxide and aluminum nitrate.

[0015] As some preferred examples of the present invention, the crystallization reaction time in step 2) is 1-5 days.

[0016] As some preferred examples of the present invention, the calcination conditions in step 3) are: calcination at 400-600° C. in air atmosphere for 3-8 hours.

[0017] As some preferred examples of the present invention, the treatment conditions in step 4) are: treatment at 50-90° C. for 3-7 hours;

[0018] Preferably, the concentration of the ammonium nitrate solution is 1.0-3.0 mol / L.

[0019] A molecular sieve adsorbent prepared by the method described above.

[0020] A post-treatment method for electrochemical synthesis of aromatic aldehyde acetal reaction liquid comprises step S1 of using the molecular sieve adsorbent prepared by the method described above to adsorb and remove heavy components in the electrochemical synthesis of aromatic aldehyde acetal reaction liquid, and step S2 of continuing to distill and purify the reaction liquid.

[0021] Electrochemical synthesis of aromatic aldehyde acetals is a commonly used preparation method in the field. For example, patent CN118756173B discloses a method for preparing diacetal by electrolysis of p-methyl anisole, CN109930171B discloses a green and efficient method for synthesizing acetal, CN114351173B discloses a method for electrochemical synthesis of 4-methoxybenzaldehyde, CN116262976B discloses a method for electrochemical synthesis of phenyl aldehyde derivatives, CN116970963A discloses a method for synthesizing p-hydroxybenzaldehyde, CN117364110A discloses a method for direct electrochemical oxidation and controllable conversion of aldehydes and ketones to CH bonds, CN117626297A discloses a method for indirect electrosynthesis of m-phenoxybenzaldehyde and its application, CN116411291A discloses a method for electrochemical synthesis of benzaldehyde, and the like.

[0022] In some preferred examples, the composition of the electrochemical synthesis of aromatic aldehyde acetal reaction solution includes: 55-80wt% solvent, 0.5-4wt% aromatic hydrocarbon / heteroaromatic hydrocarbon, 10-35wt% aromatic aldehyde acetal, 0.2-0.6wt% aromatic aldehyde, 0.5-1.1wt% heavy component, 0.2-0.9wt% electrolyte salt;

[0023] Preferably, the solvent is one or more of methanol, ethanol, isopropanol, and ether;

[0024] Preferably, the aromatic hydrocarbon / heteroaromatic hydrocarbon includes at least one benzene ring and a methyl substituent connected to the benzene ring, and preferably further optionally includes one or more of hydroxyl, methoxy, ethoxy, allyl, phenyl, naphthyl, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, nitro, methylamino, dimethylamino, diethylamino connected to the benzene ring, and more preferably, the aromatic hydrocarbon / heteroaromatic hydrocarbon is one or more of toluene, p-methoxytoluene, and p-isopropyltoluene.

[0025] Preferably, the electrolyte salt is at least one of sodium fluoride, potassium fluoride, potassium bromide, sodium bromide, and sodium benzenesulfonate.

[0026] In some preferred examples, the amount of the molecular sieve adsorbent is 15-25% of the mass of the electrochemical synthesis of aromatic aldehyde acetal reaction solution.

[0027] In some preferred examples, the adsorption conditions in step S1 are: temperature 5-60° C., operating pressure 100-300 kPaG;

[0028] Preferably, after the treatment in step S1 is completed, the content of heavy components in the electrochemical synthesis of aromatic aldehyde acetal reaction solution is reduced to below 0.1 wt %.

[0029] In some preferred examples, the distillation conditions in step S2 are: temperature of -10°C to 90°C, and operating pressure of -97 kPaG to 50 kPaG.

[0030] The beneficial effects of the present invention are as follows:

[0031] By adjusting the silicon-aluminum ratio of the molecular sieve and selecting a specific template agent, a molecular sieve adsorbent with high selectivity for the coupling heavy components in the aromatic aldehyde acetal reaction liquid was prepared. The coupling heavy components in the aromatic aldehyde acetal reaction liquid can be separated. The electrolyte salt obtained in the distillation process can be reused in the electrolysis reaction, reducing the generation of three wastes and improving the competitiveness of the device. DETAILED DESCRIPTION

[0032] The present invention is further described below by means of specific examples. The examples described in the present invention are only used to illustrate the present invention and do not limit the scope of the present invention.

[0033] Unless otherwise specified, the raw materials and reagents in the following examples of the present invention can be generally obtained through commercial channels. Among them:

[0034] The aromatic aldehyde acetal reaction liquid used in the following embodiments of the present invention takes anisaldehyde acetal reaction liquid as an example, and includes the following composition: 78.6wt% methanol, 2.5wt% p-methoxytoluene, 16.7wt% anisaldehyde acetal, 0.6wt% anisaldehyde, 0.9wt% heavy component, 0.7wt% electrolyte salt; the reaction liquid comes from the small-scale trial production device of anisaldehyde of Wanhua Chemical. The specific production method of anisaldehyde acetal reaction liquid is: in a capillary gap electrolytic cell, graphite is selected as the cathode and anode electrode materials, KF is the electrolyte salt, the reaction temperature is 50°C, and the constant current density is 7A / cm 2 , the molar concentration of methoxytoluene is: 0.5 mol / L, and the reaction time is 2.5 h.

[0035] [Example 1]

[0036] A method for preparing a molecular sieve adsorbent comprises the following steps:

[0037] 1) Silica sol is used as a silicon source and aluminum isopropoxide is used as an aluminum source. The two are added to a 2 mol / L sodium hydroxide aqueous solution at a molar ratio of 30:1 and uniformly mixed (the molar ratio of aluminum isopropoxide to sodium hydroxide is 1:45), and then a 50% 1,5-bis(N-methylpyrrolidone)pentyl ammonium bromide solution of a template agent is added (the molar ratio of aluminum isopropoxide to the template agent is 1:5);

[0038] 2) transferring the raw material mixture to a crystallization kettle and performing a crystallization reaction at 180° C. for 5 days;

[0039] 3) After the reaction is completed, the product is filtered, washed, dried, and calcined at 450° C. for 4 h to obtain a molecular sieve precursor;

[0040] 4) The molecular sieve precursor was immersed in a 1.5 mol / L ammonium nitrate solution and treated at 80° C. for 4 h to obtain a molecular sieve adsorbent A.

[0041] [Example 2]

[0042] A method for preparing a molecular sieve adsorbent comprises the following steps:

[0043] 1) Silica sol is used as a silicon source and aluminum nitrate is used as an aluminum source. The two are added to a 2 mol / L sodium hydroxide aqueous solution at a molar ratio of 50:1 and uniformly mixed (the aluminum nitrate and sodium hydroxide are added at a molar ratio of 1:55), and then 50% 1,5-bis(N-methylpyrrolidone)pentyl ammonium bromide solution and 25% tetramethylammonium hydroxide solution are added in equal molar amounts as a template agent (the aluminum nitrate and the total molar ratio of the template agent is 1:10);

[0044] 2) transferring the raw material mixture to a crystallization kettle and performing a crystallization reaction at 160° C. for 3 days;

[0045] 3) After the reaction is completed, the mixture is filtered, washed, dried, and calcined at 500° C. for 7 h to obtain a molecular sieve precursor;

[0046] 4) The molecular sieve precursor was immersed in a 2 mol / L ammonium nitrate solution and treated at 60° C. for 6 h to obtain a molecular sieve adsorbent B.

[0047] [Example 3]

[0048] A method for preparing a molecular sieve adsorbent comprises the following steps:

[0049] 1) Silica sol is used as a silicon source and aluminum isopropoxide is used as an aluminum source. The two are added to a 2 mol / L sodium hydroxide aqueous solution at a molar ratio of 65:1 and uniformly mixed (the molar ratio of aluminum isopropoxide to sodium hydroxide is 1:60), and then 50% 1,5-bis(N-methylpyrrolidone)pentyl ammonium bromide and hexadecyl trimethyl ammonium bromide as a template agent are added (the molar ratio of aluminum isopropoxide to 1,5-bis(N-methylpyrrolidone)pentyl ammonium bromide and hexadecyl trimethyl ammonium bromide is 1:10:5);

[0050] 2) transferring the raw material mixture to a crystallization reactor and performing a crystallization reaction at 200° C. for 1 day;

[0051] 3) After the reaction is completed, the mixture is filtered, washed, dried, and calcined at 600° C. for 8 h to obtain a molecular sieve precursor;

[0052] 4) The molecular sieve precursor was immersed in a 3 mol / L ammonium nitrate solution and treated at 50° C. for 7 h to obtain a molecular sieve adsorbent C.

[0053]

Application Example 1

[0054] S1. The anisaldehyde acetal reaction liquid is sent into an adsorption tank containing molecular sieve adsorbent A, wherein the addition amount of molecular sieve adsorbent A is 15% of the mass of the reaction liquid, and the reaction liquid A is obtained by treating the reaction liquid at 40° C. and 200 kPaG for 1 hour.

[0055] S2. The reaction liquid A is distilled at a tower top operating temperature of 15° C. and an operating pressure of -95 kPaG to obtain an aromatic aldehyde acetal product and a tower bottom residue B.

[0056]

Application Example 2

[0057] S1. The anisaldehyde acetal reaction liquid is sent into an adsorption tank containing a molecular sieve adsorbent B, wherein the addition amount of the molecular sieve adsorbent A is 20% of the mass of the reaction liquid, and the reaction liquid A is obtained by treating the reaction liquid at 40° C. and 200 kPaG for 0.3 h.

[0058] S2. The reaction liquid A is distilled at a tower top operating temperature of 40° C. and an operating pressure of -50 kPaG to obtain an aromatic aldehyde acetal product and a tower bottom residue B.

[0059]

Application Example 3

[0060] S1. The anisaldehyde acetal reaction liquid is sent into an adsorption tank containing a molecular sieve adsorbent C, wherein the addition amount of the molecular sieve adsorbent A is 25% of the mass of the reaction liquid, and the reaction liquid A is obtained by treating the reaction liquid at 20° C. and 200 kPaG for 0.6 h.

[0061] S2. The reaction liquid A is distilled at a tower top operating temperature of 70° C. and an operating pressure of -10 kPaG to obtain an aromatic aldehyde acetal product and a tower bottom residue B.

[0062]

Comparative Application Example 1

[0063] The aromatic aldehyde acetal reaction liquid was treated in a method substantially the same as that in Application Example 1, except that the molecular sieve adsorbent A was replaced with a ZSM-5 molecular sieve produced by China Catalyst New Materials Co., Ltd.

[0064] The heavy component contents in the reaction solution A and the tower bottom residue B of each application example were tested, and the results are shown in Table 1:

[0065] Table 1. Detection of heavy component content

[0066]

[0067] In addition, the bottom residue B (mainly composed of electrolyte salt) in each application example was uniformly recycled to the reaction of electrolyzing p-methoxytoluene to produce anisaldehyde acetal according to the following method. After applying the above method 10 times, the reaction current efficiency was calculated and recorded in Table 2.

[0068] Table 2

[0069] Reaction current efficiency / % Application Example 1 75.3 Application Example 2 74.8 Application Example 3 76.2 Comparative application example 1 69.4

[0070] The above experimental data show that by treating the aromatic aldehyde acetal reaction liquid with the molecular sieve adsorbent in the present invention, the content of heavy components can be significantly reduced, so that the electrolyte salt obtained after distillation can be reused in the electrolysis reaction, avoiding the accumulation of heavy impurities affecting the current efficiency, reducing the amount of three wastes, and improving the competitiveness of the process.

[0071] The above is only a preferred embodiment of the present invention. It should be pointed out that ordinary technicians in this field can make several improvements and supplements without departing from the method of the present invention. These improvements and supplements should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a molecular sieve adsorbent, characterized in that: The following steps are involved: 1) uniformly mixing a silicon source, an aluminum source and a sodium hydroxide aqueous solution, and then adding a template agent; the template agent is one or more of 1,5-bis(N-methylpyrrolidone)pentyl ammonium bromide, tetramethyl ammonium hydroxide, and hexadecyl trimethyl ammonium bromide, preferably a mixture of 1,5-bis(N-methylpyrrolidone)pentyl bromide and optionally tetramethyl ammonium hydroxide and hexadecyl trimethyl ammonium bromide, and more preferably, 1,5-bis(N-methylpyrrolidone)pentyl ammonium bromide accounts for half or more of the total molar amount of the template agent in the mixture; 2) transferring the raw material mixture to a crystallization kettle and performing a crystallization reaction at 160-210° C.; 3) After the reaction is completed, filtering, washing, drying, and calcining to obtain a molecular sieve precursor; 4) Immersing the molecular sieve precursor in an ammonium nitrate solution, and obtaining the molecular sieve adsorbent after treatment.

2. The method for preparing a molecular sieve adsorbent according to claim 1, characterized in that: In step 1), the molar ratio of silicon source, aluminum source, sodium hydroxide and template agent is (30-70):1:(40-65):(4-17); Preferably, the silicon source is silica sol; Preferably, the aluminum source is one or both of aluminum isopropoxide and aluminum nitrate.

3. The method for preparing a molecular sieve adsorbent according to claim 1 or 2, characterized in that: The crystallization reaction time in step 2) is 1-5 days.

4. The method for preparing the molecular sieve adsorbent according to any one of claims 1 to 3, characterized in that: The calcination conditions in step 3) are: calcination at 400-600° C. in air atmosphere for 3-8 hours.

5. The method for preparing the molecular sieve adsorbent according to any one of claims 1 to 4, characterized in that: In step 4), the treatment conditions are: 50-90° C. for 3-7 hours; Preferably, the concentration of the ammonium nitrate solution is 1.0-3.0 mol / L.

6. A molecular sieve adsorbent prepared by the method according to any one of claims 1 to 5.

7. A post-treatment method for electrochemical synthesis of aromatic aldehyde acetal reaction solution, characterized in that: The method comprises step S1 of using the molecular sieve adsorbent prepared by the method described in any one of claims 1 to 5 to adsorb and remove heavy components in the reaction solution of electrochemical synthesis of aromatic aldehyde acetal, and step S2 of continuing to distill and purify the reaction solution.

8. The post-treatment method for the electrochemical synthesis of aromatic aldehyde acetal reaction solution according to claim 7, characterized in that: The electrochemical synthesis of aromatic aldehyde acetal reaction solution comprises: 55-80wt% solvent, 0.5-4wt% aromatic hydrocarbon / heteroaromatic hydrocarbon, 10-35wt% aromatic aldehyde acetal, 0.2-0.6wt% aromatic aldehyde, 0.5-1.1wt% heavy component, and 0.2-0.9wt% electrolyte salt; Preferably, the solvent is one or more of methanol, ethanol, isopropanol, and ether; Preferably, the aromatic hydrocarbon / heteroaromatic hydrocarbon includes at least one benzene ring and a methyl substituent connected to the benzene ring, and preferably further optionally includes one or more of hydroxyl, methoxy, ethoxy, allyl, phenyl, naphthyl, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, nitro, methylamino, dimethylamino, diethylamino connected to the benzene ring, and more preferably, the aromatic hydrocarbon / heteroaromatic hydrocarbon is one or more of toluene, p-methoxytoluene, and p-isopropyltoluene.

9. The post-treatment method of the electrochemical synthesis of aromatic aldehyde acetal reaction solution according to claim 7 or 8, characterized in that: The adsorption conditions in step S1 are: temperature 5-60°C, operating pressure 100-300 kPaG; Preferably, after the treatment in step S1 is completed, the content of heavy components in the electrochemical synthesis of aromatic aldehyde acetal reaction solution is reduced to below 0.1 wt %.

10. The post-treatment method of the electrochemical synthesis of aromatic aldehyde acetal reaction solution according to any one of claims 7 to 9, characterized in that: The distillation conditions in step S2 are: temperature of -10°C to 90°C, and operating pressure of -97 kPaG to 50 kPaG.

Images