Pyridine removal process for improving quality of methyl acetate product synthesized by dimethyl ether carbonylation

Abstract

The invention relates to the technical field of chemical synthesis, in particular to a pyridine removal process for improving the product quality of methyl acetate synthesized by dimethyl ether carbonylation, which comprises the following steps: mixing dimethyl ether and carbon monoxide in proportion, and carbonylating under the action of a composite catalyst to generate methyl acetate containing pyridine impurities. Then treating and modifying an HY analysis sieve, then gradually removing pyridine impurities in the methyl acetate through a series of steps of pyridinium salt conversion, liquid separation, removal from a pyridine tank, metal organic framework adsorption, oxidation reaction, distillation, microwave-assisted rectification and the like, and finally extracting high-purity methyl acetate from the top of a rectifying tower. Parameters such as temperature, pressure and material ratio in each step are accurately controlled. The modified HY analysis sieve and the metal organic framework material are prepared and used for adsorption operation, strong interaction with the pyridine impurities can be formed, the adsorption effect is enhanced, the removal efficiency of the pyridine impurities is further guaranteed, and the refining degree of the product is improved.

Description

Technical Field

[0001] The invention relates to the technical field of chemical synthesis, and in particular to a pyridine removal process for improving the quality of a product synthesizing methyl acetate by carbonylation of dimethyl ether. Background Art

[0002] In the industrial production of dimethyl ether carbonylation to methyl acetate, DMTE-202 catalyst is commonly used. However, pyridine desorption occurs during the use of this catalyst, causing the pyridine content in the methyl acetate product to exceed the standard range.

[0003] This problem seriously affects product quality, disrupts the subsequent chemical reaction process, reduces the activity and selectivity of the catalyst in the subsequent reaction, deteriorates product color, and increases impurity content, which greatly increases the difficulty and cost of subsequent reaction processing, and has a serious restrictive effect on the economic benefits of the entire production process and the stability of product quality.

[0004] Therefore, an effective solution is urgently needed to reduce the pyridine content in methyl acetate to meet the demand for high-quality products in industrial production. Summary of the invention

[0005] In view of the above-mentioned shortcomings of the prior art, the present invention provides a pyridine removal process for improving the product quality of methyl acetate synthesized by carbonylation of dimethyl ether, which can effectively solve the problems mentioned in the prior art.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0007] The present invention provides a pyridine removal process for improving the quality of the product of dimethyl ether carbonylation synthesis of methyl acetate, comprising the following steps:

[0008] Step 1, dimethyl ether and carbon monoxide are mixed in a molar ratio of 1:1.5, and introduced into a carbonylation reactor, and a carbonylation reaction is carried out under the catalytic action of a composite catalyst system composed of a DMTE-202 catalyst and a nano-metal oxide in a mass ratio of 1:10-1:20, wherein the reaction temperature in the carbonylation reactor is controlled at 180° C.-200° C. and the pressure is controlled at 2.5 MPa-3.0 MPa to generate methyl acetate containing pyridine impurities;

[0009] Step 2, after calcining the commercial HY analysis sieve at 500-600° C. for 4-6 hours, adding 0.5-1.0 mol / L zinc nitrate solution at a mass ratio of 1:5-1:10, stirring at a temperature of 70-80° C. and a rotation speed of 200-300 r / min for 6-8 hours, filtering, washing with water to pH 6-7, and vacuum drying at a temperature of 100-120° C. for 8-10 hours to obtain an intermediate product;

[0010] Step 3, the intermediate product and toluene are mixed at a ratio of 1:8-1:12, a coupling agent with a mass fraction of 10%-15% is added under protective gas, and an amino-modified mesoporous silica material with a mass ratio of 1:3-1:5 to the HY analysis sieve is added, refluxed at 90-110°C for 8-10h, centrifuged, washed with toluene and ethanol in a ratio of 1:1, and vacuum dried at 80-100°C for 10-12h to obtain a modified HY analysis sieve;

[0011] Step 4, reacting methyl acetate containing pyridine impurities with halogenated hydrocarbons under alkaline conditions, the reaction temperature is 60-80° C., the reaction time is 2-4 hours, so that part of the pyridine impurities are converted into separable pyridinium salts, and the molar ratio of the halogenated hydrocarbon to pyridine is 1.2-1.5:1;

[0012] Step 5, performing a liquid separation operation on the mixture treated in step 4 to separate the lower layer liquid containing the pyridinium salt to obtain preliminarily purified methyl acetate;

[0013] Step 6, loading the modified HY analytical sieve into a methyl acetate depyridinization tank, flowing the preliminarily purified methyl acetate into the methyl acetate depyridinization tank, removing residual pyridine impurities, and obtaining re-purified methyl acetate;

[0014] Step 7, introducing the purified methyl acetate into an adsorption column equipped with a metal organic framework material, the adsorption temperature is 30-40° C., the adsorption time is 1-2 hours, and the pyridine impurity is adsorbed;

[0015] Step 8, pumping the methyl acetate treated by the adsorption column into a reactor, adding hydrogen peroxide and an organic acid catalyst, and performing an oxidation reaction at 40-50° C. for 3-5 hours, wherein the molar ratio of hydrogen peroxide to methyl acetate is 0.05:1-0.1:1, and the amount of the organic acid catalyst is 0.5%-1% of the mass of methyl acetate;

[0016] Step 9, distilling the mixture after the oxidation reaction, collecting the fraction at 55-57° C., and obtaining preliminarily distilled methyl acetate;

[0017] Step 10, the preliminarily distilled methyl acetate flows into a distillation tower at a flow rate of 0.6-2.5m³ / h, the distillation tower adopts microwave assisted heating, the microwave power is controlled at 300-500W, the tower top pressure is controlled at 0.08-0.15MPa, the temperature is controlled at 55-57°C, the tower bottom temperature is controlled at 63-68°C, the reflux ratio is controlled at 2-4, and high-purity methyl acetate is produced from the tower top.

[0018] Preferably, the nano metal oxide in step 1 is titanium dioxide nanoparticles.

[0019] Preferably, the protective gas in step 3 is nitrogen, the coupling agent is γ-aminopropyltriethoxysilane, and the pore size distribution of the amino-modified mesoporous silica material is 2-50 nm.

[0020] Preferably, the alkaline condition in step 4 is provided by sodium hydroxide or potassium hydroxide at a concentration of 0.5-1 mol / L.

[0021] Preferably, in step 6, the temperature in the methyl acetate depyridination tank is 40° C.-50° C., and the pressure is 0.3 MPa-0.4 MPa.

[0022] Preferably, the particle size of the ZIF-8 metal organic framework material in step 7 is 100-500 nm.

[0023] Preferably, the organic acid catalyst in step 8 is p-toluenesulfonic acid.

[0024] Preferably, the number of plates of the distillation tower in step 10 is 40-60.

[0025] Compared with the known prior art, the technical solution provided by the present invention has the following beneficial effects:

[0026] (1) The present invention prepares and uses modified HY analytical sieves and metal organic framework materials, such as ZIF-8, for adsorption operations. These materials have high specific surface area, suitable pore size distribution and specific functional group modification, and can form strong interactions with pyridine impurities, enhance the adsorption effect, further ensure the removal efficiency of pyridine impurities, and improve the degree of product refinement.

[0027] (2) The present invention uses a composite catalyst system consisting of DMTE-202 catalyst and nano-metal oxide in the carbonylation reaction step, which not only improves the conversion rate of dimethyl ether and the selectivity of methyl acetate, but also has a certain inhibitory effect on the formation of pyridine impurities, optimizes the entire reaction process, reduces the generation of pyridine impurities from the source, and improves the economy of the reaction and the quality of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0029] Figure 1 It is a process flow chart of the present invention. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] The present invention will be further described below in conjunction with the embodiments.

[0032] Embodiment 1:

[0033] (1) Dimethyl ether and carbon monoxide were mixed in a molar ratio of 1:1.5 and introduced into a carbonylation reactor. A composite catalyst system consisting of DMTE-202 catalyst and titanium dioxide nanoparticles in a mass ratio of 1:15 was used to carry out a carbonylation reaction at a reaction temperature of 190°C and a pressure of 2.8 MPa to produce methyl acetate containing pyridine impurities.

[0034] (2) The commercial HY analysis sieve was calcined at 550°C for 5 h, and then 0.8 mol / L zinc nitrate solution was added at a mass ratio of 1:8. The mixture was stirred at 75°C and 250 r / min for 7 h. The mixture was filtered and washed with water to pH 6.5. The mixture was vacuum dried at 110°C for 9 h to obtain an intermediate product.

[0035] (3) The intermediate product was mixed with toluene at a ratio of 1:10, and a γ-aminopropyltriethoxysilane coupling agent with a mass fraction of 12% was added under nitrogen protection. An amino-modified mesoporous silica material (pore size distribution of 30 nm) was added at a mass ratio of 1:4 to the HY analysis sieve. The mixture was refluxed at 100 °C for 9 h, centrifuged, washed with toluene and ethanol in a ratio of 1:1, and vacuum dried at 90 °C for 11 h to obtain the modified HY analysis sieve.

[0036] (4) Methyl acetate containing pyridine impurities is reacted with a halogenated hydrocarbon (such as chloroform) under alkaline conditions provided by a 0.8 mol / L sodium hydroxide solution at a temperature of 70°C for 3 hours and a molar ratio of the halogenated hydrocarbon to pyridine of 1.3:1, so that part of the pyridine impurities are converted into a separable pyridinium salt.

[0037] (5) The mixture treated in step 4 was separated by a separatory funnel and allowed to stand for 45 minutes to separate the lower layer containing the pyridinium salt to obtain preliminarily purified methyl acetate.

[0038] (6) The modified HY analytical sieve is loaded into a methyl acetate depyridinization tank (temperature of 45°C, pressure of 0.35 MPa), and the preliminarily purified methyl acetate is flowed into the methyl acetate depyridinization tank to remove the residual pyridine impurities, thereby obtaining re-purified methyl acetate.

[0039] (7) The purified methyl acetate was introduced into an adsorption column filled with ZIF-8 metal organic framework material (particle size 300 nm) at an adsorption temperature of 35 °C and an adsorption time of 1.5 h to adsorb pyridine impurities.

[0040] (8) The methyl acetate treated by the adsorption column was pumped into the reactor, and hydrogen peroxide (the molar ratio of hydrogen peroxide to methyl acetate was 0.08:1) and p-toluenesulfonic acid (the amount was 0.8% of the mass of methyl acetate) were added, and the oxidation reaction was carried out at 45°C for 4 hours.

[0041] (9) The mixture after the oxidation reaction is distilled, and the fraction at 56° C. is collected to obtain preliminarily distilled methyl acetate.

[0042] (10) The preliminarily rectified methyl acetate was flowed into a distillation tower at a flow rate of 1.5 m³ / h. The distillation tower was heated by microwave. The microwave power was controlled at 400 W, the tower top pressure was controlled at 0.12 MPa, the temperature was controlled at 56 °C, the tower bottom temperature was controlled at 65 °C, and the reflux ratio was controlled at 3. High-purity methyl acetate was extracted from the tower top.

[0043] High-purity methyl acetate was tested. The pyridine content and purity of methyl acetate in high-purity methyl acetate were tested by gas chromatography (GC), and other impurities in high-purity methyl acetate were tested by gas chromatography-mass spectrometry (GC-MS), including common methanol, ethanol, methyl formate, etc. The test results are shown in Table 1:

[0044] Table 1, Examples 1-3 and Comparative Examples Test Table

[0045] Example Pyridine content (ppm) Purity of methyl acetate (%) Other impurities content (ppm) Example 1 8 99.95 20 Example 2 6 99.97 15 Example 3 5 99.98 10 Comparative Example 500 98.00 500

[0046] Under the process conditions of Example 1, through a series of steps, such as carbonylation reaction of a specific composite catalyst system, fine preparation and modification of HY analytical sieve, conversion and separation of pyridinium salt, metal organic framework adsorption, oxidation reaction and microwave-assisted distillation, not only the pyridine content was significantly reduced to 8 ppm, but also the purity of methyl acetate was increased to 99.95%, and the content of other impurities was also controlled at a relatively low level (20 ppm), which strongly proved that the process can effectively remove various impurities in methyl acetate and ensure the high purity of the product.

[0047] Embodiment 2:

[0048] (1) Dimethyl ether and carbon monoxide were mixed in a molar ratio of 1:1.5 and introduced into a carbonylation reactor. A composite catalyst system consisting of DMTE-202 catalyst and titanium dioxide nanoparticles in a mass ratio of 1:10 was used to carry out a carbonylation reaction at a reaction temperature of 185°C and a pressure of 2.6 MPa to produce methyl acetate containing pyridine impurities.

[0049] (2) The commercial HY analysis sieve was calcined at 520°C for 6 h, and then 0.5 mol / L zinc nitrate solution was added at a mass ratio of 1:5. The mixture was stirred at 70°C and 220 r / min for 8 h. The mixture was filtered and washed with water to pH 6. The mixture was vacuum dried at 105°C for 10 h to obtain an intermediate product.

[0050] (3) The intermediate product was mixed with toluene in a ratio of 1:8, and a γ-aminopropyltriethoxysilane coupling agent with a mass fraction of 10% was added under nitrogen protection. An amino-modified mesoporous silica material (pore size distribution of 20 nm) was added in a mass ratio of 1:3 to the HY analysis sieve. The mixture was refluxed at 95 °C for 10 h, centrifuged, washed with toluene and ethanol in a ratio of 1:1, and vacuum dried at 85 °C for 12 h to obtain the modified HY analysis sieve.

[0051] (4) Methyl acetate containing pyridine impurities is reacted with a halogenated hydrocarbon (such as ethyl bromide) under alkaline conditions provided by a 0.5 mol / L potassium hydroxide solution at a reaction temperature of 65°C for 4 hours. The molar ratio of the halogenated hydrocarbon to pyridine is 1.2:1, so that part of the pyridine impurities are converted into a separable pyridinium salt.

[0052] (5) The mixture treated in step 4 was separated by a separatory funnel and allowed to stand for 60 minutes to separate the lower layer containing the pyridinium salt to obtain preliminarily purified methyl acetate.

[0053] (6) The modified HY analytical sieve is loaded into a methyl acetate depyridinization tank (temperature of 42°C, pressure of 0.3 MPa), and the preliminarily purified methyl acetate is flowed into the methyl acetate depyridinization tank to remove the residual pyridine impurities, thereby obtaining a second purified methyl acetate.

[0054] (7) The purified methyl acetate was introduced into an adsorption column filled with ZIF-8 metal organic framework material (particle size 200 nm) at an adsorption temperature of 32 °C and an adsorption time of 2 h to adsorb pyridine impurities.

[0055] (8) The methyl acetate treated by the adsorption column was pumped into the reactor, and hydrogen peroxide (the molar ratio of hydrogen peroxide to methyl acetate was 0.05:1) and p-toluenesulfonic acid (the amount was 0.5% of the mass of methyl acetate) were added, and the oxidation reaction was carried out at 42°C for 5 hours.

[0056] (9) The mixture after the oxidation reaction is distilled, and the fraction at 55° C. is collected to obtain preliminarily distilled methyl acetate.

[0057] (10) The preliminarily distilled methyl acetate was flowed into a distillation tower at a flow rate of 0.6 m³ / h. The distillation tower was heated by microwave. The microwave power was controlled at 350 W, the tower top pressure was controlled at 0.08 MPa, the temperature was controlled at 55 °C, the tower bottom temperature was controlled at 63 °C, and the reflux ratio was controlled at 2. High-purity methyl acetate was extracted from the tower top.

[0058] The same detection method as in Example 1 was adopted for high-purity methyl acetate, and the detection results are shown in Table 1.

[0059] After adjusting some process parameters in Example 2, the pyridine content was further reduced to 6 ppm, the purity of methyl acetate reached 99.97%, and the content of other impurities was reduced to 15 ppm, which shows that reasonable optimization of process parameters can further improve the impurity removal effect, enhance the effectiveness and accuracy of the process, and meet the production needs with higher quality requirements.

[0060] Embodiment 3:

[0061] (1) Dimethyl ether and carbon monoxide were mixed in a molar ratio of 1:1.5 and introduced into a carbonylation reactor. A composite catalyst system consisting of DMTE-202 catalyst and titanium dioxide nanoparticles in a mass ratio of 1:20 was used to carry out a carbonylation reaction at a reaction temperature of 200°C and a pressure of 3.0 MPa to produce methyl acetate containing pyridine impurities.

[0062] (2) The commercial HY analysis sieve was calcined at 600°C for 4 h, and then a 1.0 mol / L zinc nitrate solution was added at a mass ratio of 1:10. The mixture was stirred at 80°C and 300 r / min for 6 h. The mixture was filtered and washed with water to pH 7. The mixture was vacuum dried at 120°C for 8 h to obtain an intermediate product.

[0063] (3) The intermediate product was mixed with toluene in a ratio of 1:12, and γ-aminopropyltriethoxysilane coupling agent with a mass fraction of 15% was added under nitrogen protection. An amino-modified mesoporous silica material (pore size distribution of 50 nm) with a mass ratio of 1:5 to HY analysis sieve was added. The mixture was refluxed at 110 °C for 8 h, centrifuged, washed with toluene and ethanol in a ratio of 1:1, and vacuum dried at 100 °C for 10 h to obtain the modified HY analysis sieve.

[0064] (4) Methyl acetate containing pyridine impurities is reacted with a halogenated hydrocarbon (such as iodomethane) under alkaline conditions provided by a 1.0 mol / L sodium hydroxide solution at a reaction temperature of 80°C for 2 hours and a molar ratio of the halogenated hydrocarbon to pyridine of 1.5:1, so that part of the pyridine impurities are converted into a separable pyridinium salt.

[0065] (5) The mixture treated in step 4 was separated by a separatory funnel and allowed to stand for 30 minutes to separate the lower layer containing the pyridinium salt to obtain preliminarily purified methyl acetate.

[0066] (6) The modified HY analytical sieve is loaded into a methyl acetate depyridinization tank (temperature of 50°C, pressure of 0.4 MPa), and the preliminarily purified methyl acetate is flowed into the methyl acetate depyridinization tank to remove the residual pyridine impurities, thereby obtaining a second purified methyl acetate.

[0067] (7) The purified methyl acetate was introduced into an adsorption column filled with ZIF-8 metal organic framework material (particle size 500 nm) at an adsorption temperature of 40 °C and an adsorption time of 1 hour to adsorb pyridine impurities.

[0068] (8) The methyl acetate treated by the adsorption column was pumped into the reactor, and hydrogen peroxide (the molar ratio of hydrogen peroxide to methyl acetate was 0.1:1) and p-toluenesulfonic acid (the amount was 1% of the mass of methyl acetate) were added, and the oxidation reaction was carried out at 50°C for 3 hours.

[0069] (9) The mixture after the oxidation reaction is distilled, and the fraction at 57° C. is collected to obtain preliminarily distilled methyl acetate.

[0070] (10) The preliminarily distilled methyl acetate was flowed into a distillation tower at a flow rate of 2.5 m³ / h. The distillation tower was heated by microwave assistance. The microwave power was controlled at 500 W, the tower top pressure was controlled at 0.15 MPa, the temperature was controlled at 57 °C, the tower bottom temperature was controlled at 68 °C, and the reflux ratio was controlled at 4. High-purity methyl acetate was extracted from the tower top.

[0071] The same detection method as in Example 1 was adopted for high-purity methyl acetate, and the detection results are shown in Table 1.

[0072] Example 3 adopts a specific combination of process parameters to reduce the pyridine content in the product to 5 ppm, the purity of methyl acetate is as high as 99.98%, and the content of other impurities is only 10 ppm, which once again verifies the high efficiency and stability of the process, and can effectively remove pyridine and other impurities under different parameter settings to ensure that the product quality meets high standards.

[0073] Comparative Example:

[0074] (1) Dimethyl ether and carbon monoxide were mixed in a molar ratio of 1:1.5 and introduced into a carbonylation reactor. Using only DMTE-202 catalyst, a carbonylation reaction occurred at a reaction temperature of 180°C and a pressure of 2.5 MPa to produce methyl acetate containing pyridine impurities.

[0075] (2) The methyl acetate containing pyridine impurities is subjected to a simple water washing operation to remove some water-soluble impurities, but most of the pyridine impurities are still retained in the methyl acetate.

[0076] (3) The methyl acetate after water washing is directly fed into a common distillation tower at a flow rate of 1.0 m³ / h. The top pressure of the tower is controlled at 0.1 MPa, the temperature is controlled at 56°C, the bottom temperature is controlled at 65°C, the reflux ratio is controlled at 3, and the product is taken from the top of the tower.

[0077] The comparative example product was tested using the same method as in Example 1, and the test results are shown in Table 1.

[0078] The comparative example only adopted a conventional carbonylation reaction followed by simple water washing and ordinary distillation, and did not use the innovative process in the example, resulting in a large amount of residual pyridine impurities (500 ppm), a methyl acetate purity of only 98.00%, and other impurity contents as high as 500 ppm, which was in sharp contrast to Examples 1-3, highlighting the significant advantages and key role of the new process in solving the methyl acetate impurity problem, and providing a reliable technical solution for the production of high-purity methyl acetate.

[0079] By comparing Examples 1-3 with the comparative example, it can be seen that the HY analysis sieve is specially modified and combined with specific reaction and distillation conditions to effectively remove pyridine impurities in the product of dimethyl ether carbonylation to methyl acetate, and significantly improve the purity and yield of methyl acetate. Compared with the unmodified HY analysis sieve in the comparative example, the process in the embodiment shows obvious advantages in pyridine removal effect, product purity and yield, which fully proves the innovation and effectiveness of the process of the present invention, and provides a reliable technical solution for the industrial production of high-quality methyl acetate, with good application prospects and economic benefits.

[0080] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements will not cause the essence of the corresponding technical solutions to deviate from the protection scope of the technical solutions of the embodiments of the present invention.

Claims

1. A pyridine removal process for improving the product quality of methyl acetate synthesized by carbonylation of dimethyl ether, characterized in that: The following steps are involved: Step 1, dimethyl ether and carbon monoxide are mixed in a molar ratio of 1:1.5, and introduced into a carbonylation reactor, and a carbonylation reaction is carried out under the catalytic action of a composite catalyst system composed of a DMTE-202 catalyst and a nano-metal oxide in a mass ratio of 1:10-1:20, wherein the reaction temperature in the carbonylation reactor is controlled at 180° C.-200° C. and the pressure is controlled at 2.5 MPa-3.0 MPa to generate methyl acetate containing pyridine impurities; Step 2, after calcining the commercial HY analysis sieve at 500-600° C. for 4-6 hours, adding 0.5-1.0 mol / L zinc nitrate solution at a mass ratio of 1:5-1:10, stirring at a temperature of 70-80° C. and a rotation speed of 200-300 r / min for 6-8 hours, filtering, washing with water to pH 6-7, and vacuum drying at a temperature of 100-120° C. for 8-10 hours to obtain an intermediate product; Step 3, the intermediate product and toluene are mixed at a ratio of 1:8-1:12, a coupling agent with a mass fraction of 10%-15% is added under protective gas, and an amino-modified mesoporous silica material with a mass ratio of 1:3-1:5 to the HY analysis sieve is added, refluxed at 90-110°C for 8-10h, centrifuged, washed with toluene and ethanol in a ratio of 1:1, and vacuum dried at 80-100°C for 10-12h to obtain a modified HY analysis sieve; Step 4, reacting methyl acetate containing pyridine impurities with halogenated hydrocarbons under alkaline conditions, the reaction temperature is 60-80° C., the reaction time is 2-4 hours, so that part of the pyridine impurities are converted into separable pyridinium salts, and the molar ratio of the halogenated hydrocarbon to pyridine is 1.2-1.5:1; Step 5, performing a liquid separation operation on the mixture treated in step 4 to separate the lower layer liquid containing the pyridinium salt to obtain preliminarily purified methyl acetate; Step 6, loading the modified HY analytical sieve into a methyl acetate depyridinization tank, flowing the preliminarily purified methyl acetate into the methyl acetate depyridinization tank, removing residual pyridine impurities, and obtaining re-purified methyl acetate; Step 7, introducing the purified methyl acetate into an adsorption column equipped with a metal organic framework material, the adsorption temperature is 30-40° C., the adsorption time is 1-2 hours, and the pyridine impurity is adsorbed; Step 8, pumping the methyl acetate treated by the adsorption column into a reactor, adding hydrogen peroxide and an organic acid catalyst, and performing an oxidation reaction at 40-50° C. for 3-5 hours, wherein the molar ratio of hydrogen peroxide to methyl acetate is 0.05:1-0.1:1, and the amount of the organic acid catalyst is 0.5%-1% of the mass of methyl acetate; Step 9, distilling the mixture after the oxidation reaction, collecting the fraction at 55-57° C., and obtaining preliminarily distilled methyl acetate; Step 10, the preliminarily distilled methyl acetate flows into a distillation tower at a flow rate of 0.6-2.5m³ / h, the distillation tower adopts microwave assisted heating, the microwave power is controlled at 300-500W, the tower top pressure is controlled at 0.08-0.15MPa, the temperature is controlled at 55-57°C, the tower bottom temperature is controlled at 63-68°C, the reflux ratio is controlled at 2-4, and high-purity methyl acetate is produced from the tower top.

2. A pyridine removal process for improving the product quality of methyl acetate synthesized by carbonylation of dimethyl ether according to claim 1, characterized in that: The nano metal oxide in step 1 is titanium dioxide nanoparticles.

3. A pyridine removal process for improving the product quality of methyl acetate synthesized by carbonylation of dimethyl ether according to claim 1, characterized in that: The protective gas in step 3 is nitrogen, the coupling agent is γ-aminopropyltriethoxysilane, and the pore size distribution of the amino-modified mesoporous silica material is 2-50 nm.

4. A pyridine removal process for improving the product quality of methyl acetate synthesized by carbonylation of dimethyl ether according to claim 1, characterized in that: The alkaline condition in step 4 is provided by sodium hydroxide or potassium hydroxide with a concentration of 0.5-1 mol / L.

5. A pyridine removal process for improving the product quality of methyl acetate synthesized by carbonylation of dimethyl ether according to claim 1, characterized in that: In step 6, the temperature in the methyl acetate depyridinylation tank is 40° C.-50° C., and the pressure is 0.3 MPa-0.4 MPa.

6. A pyridine removal process for improving the product quality of methyl acetate synthesized by carbonylation of dimethyl ether according to claim 1, characterized in that: The particle size of the ZIF-8 metal organic framework material in step 7 is 100-500 nm.

7. A pyridine removal process for improving the product quality of methyl acetate synthesized by carbonylation of dimethyl ether according to claim 1, characterized in that: The organic acid catalyst in step 8 is p-toluenesulfonic acid.

8. The pyridine removal process for improving the product quality of methyl acetate synthesized by carbonylation of dimethyl ether according to claim 1, characterized in that: The number of plates of the distillation tower in step 10 is 40-60.

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