A method for preparing chromatographically pure methanol

Abstract

The present application relates to the field of chromatographic pure methanol, and particularly to a preparation method of chromatographic pure methanol. The preparation method of chromatographic pure methanol comprises the following preparation steps: S1, pre-adsorption treatment: selecting industrial-grade methanol and placing it in a pretreatment adsorption device, pre-adsorption treatment, and adding potassium hydroxide powder for alkaline hydrolysis treatment; S2, secondary purification: sequentially adsorbing and removing impurities of the alkali-hydrolyzed methanol material through a composite filter material for secondary purification treatment; S3, rectification and impurity removal: placing the secondary-purified methanol material in a rectification tower, adjusting parameters of rectification and impurity removal, removing top fraction, and collecting middle fraction; and S4, storage treatment. The present application effectively solves the problem that a single process is difficult to completely remove impurities through the synergistic effect of multiple links: pre-adsorption combined with alkaline hydrolysis to preliminarily remove easily treated impurities, secondary purification through a composite material to deeply and targetedly remove impurities, rectification to further separate trace impurities, and storage treatment to prevent secondary pollution. The methanol is not prone to deterioration during storage.

Description

Technical Field

[0001] This invention relates to the field of chromatographically pure methanol, and more specifically to a method for preparing chromatographically pure methanol. Background Technology

[0002] Chromatographically pure methanol is a key mobile phase in precision analytical fields such as liquid chromatography and mass spectrometry. Its purity and stability directly affect the accuracy, reproducibility, and detection sensitivity of analytical results. Industrial-grade methanol introduces various impurities during production, including aldehydes, esters, unsaturated hydrocarbons, moisture, and trace metal ions. If these impurities are not effectively removed, they can lead to baseline drift, increased detection limits, and even interference with the qualitative and quantitative analysis of target analytes.

[0003] In response to the aforementioned existing technologies, the inventors have discovered that the existing processes for purifying industrial methanol to chromatographically pure methanol mainly include steps such as adsorption, distillation, and chemical treatment. However, traditional processes have many shortcomings. The pretreatment stage often uses conventional activated carbon or molecular sieves for adsorption, which has poor selectivity for specific impurities and is difficult to efficiently remove stubborn impurities such as olefins and esters. Multiple adsorption steps are often required to achieve a preliminary purification effect, making the process cumbersome and inefficient. Secondly, the purification stage often relies on a single filter material or a simple combination of processes, making it difficult to achieve multiple purification goals such as dehydration, aldehyde removal, and ester removal simultaneously, resulting in insufficient purification depth and product purity that fails to meet the requirements of high-precision analysis. Finally, the preparation process of existing filter materials is complex, and the filtered product is prone to reintroducing impurities during storage due to oxidation, moisture absorption, etc., affecting storage stability and shortening shelf life. Summary of the Invention

[0004] In view of the technical problems existing in the prior art, the present invention provides a method for preparing chromatographically pure methanol and the method thereof.

[0005] A method for preparing chromatographically pure methanol, employing the following technical solution:

[0006] A method for preparing chromatographically pure methanol includes the following preparation steps:

[0007] S1. Pre-adsorption treatment: Select industrial grade methanol and place it in a pre-adsorption device for pre-adsorption treatment and add potassium hydroxide powder. Then, reflux alkaline hydrolysis treatment at 65-70℃ for 3-5 hours.

[0008] S2. Secondary purification: The methanol material after alkaline hydrolysis is sequentially passed through composite filter material for adsorption and impurity removal, undergoing secondary purification treatment.

[0009] S3. Distillation and purification: The methanol material after secondary purification is placed in a distillation column, the distillation and purification parameters are adjusted, the top fraction is removed, and the middle fraction is collected.

[0010] S4. Storage and processing: After the collected middle fraction is filtered through a filter element, it is filled into containers under nitrogen protection and stored in containers under inert gas protection to prepare chromatographically pure methanol.

[0011] Through the above technical solution, this application forms a complete purification chain through four steps: pre-adsorption treatment, secondary purification, distillation for impurity removal, and storage treatment. Utilizing the synergistic effect of multiple stages: pre-adsorption combined with alkaline hydrolysis initially removes easily treatable impurities; secondary purification uses composite materials for deep, targeted impurity removal; distillation further separates trace impurities; and storage treatment prevents secondary contamination. The overall process achieves full-chain control from crude purification to refined purification and stable storage, effectively solving the problem that single processes cannot completely remove impurities, ensuring that the final product purity meets chromatographic analysis requirements, and that it is not easily degraded during storage.

[0012] Furthermore, the pretreatment adsorption process uses activated carbon fiber modified by phosphate soaking.

[0013] Through the above technical solution, the pretreatment in this application uses activated carbon fiber modified by phosphate impregnation. Phosphate modification can adjust the pore structure and surface chemical properties of activated carbon fiber, enhancing its selective adsorption capacity for specific unsaturated impurities in industrial methanol. Compared with unmodified materials, it can capture target impurities more efficiently, reduce the pressure of subsequent purification, make the impurity removal in the pre-adsorption stage more targeted, lay a purer raw material foundation for subsequent alkaline hydrolysis and deep purification, and improve the overall impurity removal efficiency of the process.

[0014] Furthermore, the composite filter material comprises a porous ceramic matrix, a first hydrophilic molecular sieve membrane, and a second FAU-type molecular sieve membrane, which are stacked sequentially from the inside out.

[0015] Through the above technical solution, this application selects a porous ceramic matrix as the composite filter material, combining it with a first hydrophilic molecular sieve membrane and a second FAU-type molecular sieve membrane to form a layered structure. Each layer of material has complementary functions: the matrix provides structural support, the first membrane focuses on the selective removal of specific impurities, and the second membrane catalyzes or adsorbs another type of impurity. This multi-layer synergy achieves simultaneous deep purification of multiple impurities, avoiding the limitations of single-material purification capabilities and significantly improving the comprehensiveness and thoroughness of secondary purification.

[0016] Furthermore, the porous ceramic matrix is ​​manufactured using the following technical solution:

[0017] After mixing and grinding alumina powder and ammonium bicarbonate, polyvinyl alcohol and dibutyl phthalate are added, followed by anhydrous ethanol in batches. The mixture is then wet-milled and collected to obtain a slurry. The slurry is placed in a mold, demolded, and sintered. After cooling to room temperature, it is washed and dried to obtain the porous ceramic matrix.

[0018] Through the above technical solution, this application optimizes the raw material ratio and controls the sintering parameters to form a support structure with reasonable pore distribution and suitable mechanical strength. This matrix can provide a stable adhesion substrate for the upper molecular sieve membrane and ensure the smooth passage of methanol material, avoiding the impact of structural defects on mass transfer efficiency or membrane bonding stability, and ensuring the stable performance of the composite filter material during use.

[0019] Furthermore, the first hydrophilic molecular sieve membrane is manufactured using the following technical solution:

[0020] Sodium aluminosilicate sol was taken and sodium bisulfite-silica composite nanoparticles were added. After ultrasonic dispersion, a synthesis solution was formed. A porous ceramic matrix was placed in the synthesis solution, heated and kept at a constant temperature for reaction, and then washed and dried to prepare the first hydrophilic molecular sieve membrane.

[0021] Through the above technical solution, this application prepares a molecular sieve membrane using sodium aluminosilicate sol and bisulfite-silica composite nanoparticles. The hydrophilic structure of the membrane allows for selective adsorption of moisture, while the nanoparticles, through dispersion and embedding, retain some active components during the purification process. This design enables the membrane material to simultaneously possess dehydration and stabilizing factor supply capabilities, improving dehydration efficiency in the purification stage and ensuring product storage stability, thus achieving multiple functions in one material.

[0022] Furthermore, the second FAU-type molecular sieve membrane is manufactured using the following technical solution:

[0023] A porous ceramic substrate coated with a first hydrophilic molecular sieve membrane was immersed in a sodium silicate solution. After immersion, it was coated with FAU seed suspension, pulled up and dried to prepare a pretreated substrate.

[0024] Silica sol, sodium aluminate, tetrapropylammonium hydroxide, sodium bisulfite-silica particles are stirred, mixed, and ultrasonically dispersed. After collecting the dispersion, the pretreated substrate is placed in the dispersion, heated and pressure-treated by programmed temperature rise, cooled to room temperature, calcined, washed and dried to prepare a composite filter material coated with a second FAU type molecular sieve membrane.

[0025] Through the above technical solution, this application prepares a second FAU-type molecular sieve membrane by seed coating and secondary growth. Its specific structure enables efficient catalysis or adsorption of aldehyde impurities, and the synergistic effect of sodium bisulfite-silica particles enhances the aldehyde removal effect. Simultaneously, the preparation of the pretreated substrate ensures a tight bond between the membrane layer and the underlying material, preventing interlayer delamination. This process allows the second membrane to not only deeply remove stubborn impurities such as aldehydes but also synergistically provide stabilizing factors with the first membrane, improving overall purification performance.

[0026] Furthermore, the parameters for the distillation and impurity removal are as follows:

[0027] The tower has 60 trays, with a 3m high packed section at the top and a 2m high plate section at the bottom. The bottom temperature is controlled at 70-75℃, the top temperature at 65-70℃, and the reflux ratio is 5-8:1.

[0028] Through the above technical solution, this application employs a distillation column with a specific structure and parameter settings for distillation and impurity removal. The combination of packed and plate sections optimizes mass transfer efficiency, while the control of temperature and reflux ratio precisely manages the separation of impurities with different boiling points. This design balances separation accuracy and energy consumption, effectively removing both low- and high-boiling-point impurities while avoiding excessive energy consumption or yield reduction caused by over-distillation, thus achieving an optimal balance between the purity and yield of the middle fraction.

[0029] Furthermore, the adsorption flow rate of the pretreatment adsorption process is 300-500 mL / min.

[0030] Through the above technical solution, this application controls the pretreatment adsorption flow rate. By setting an appropriate flow rate, it ensures sufficient contact between industrial methanol and modified activated carbon fiber, allowing impurities enough time to be adsorbed and captured, while avoiding low efficiency caused by excessively slow flow rates. A reasonable flow rate guarantees the impurity removal effect in the pre-adsorption stage while also considering process efficiency, preventing impurity residue due to insufficient contact, which could affect the load of subsequent purification steps and the final product quality.

[0031] In summary, this application has the following beneficial effects:

[0032] First, this application employs a pre-adsorption technique combined with alkaline hydrolysis to remove impurities, followed by deep synergistic purification using a porous ceramic matrix composite bimolecular sieve membrane composite filter material. Finally, it utilizes a fully chained process with a precisely separated structure through an optimized distillation column. This process can specifically remove various impurities such as olefins, esters, aldehydes, and moisture from industrial methanol, solving the problem of incomplete and inadequate purification by traditional single processes. The final product purity fully meets the stringent requirements of precision chromatographic analysis for the mobile phase.

[0033] Secondly, the composite filter material used in this application integrates the three functions of support, purification, and stabilization without the need for additional stabilizers; at the same time, the parameters of the pretreatment, purification, and distillation processes are coordinated, simplifying the cumbersome process of traditional multi-stage separate operations, reducing the types of raw materials and equipment investment, and improving production efficiency while reducing production costs.

[0034] Third, this application ensures a balance between pre-adsorption effect and efficiency by controlling the adsorption flow rate, and optimizes the structure and parameters of the distillation column to balance separation accuracy and energy consumption, avoiding a decrease in yield due to over-distillation; during the storage stage, relying on the stabilizing factors retained in the purification process and nitrogen protection, it effectively inhibits product oxidation and deterioration, extends shelf life, and solves the pain points of low efficiency, high energy consumption and easy deterioration of products during storage in traditional processes, taking into account both the practicality of industrial production and the long-term stability of products. Detailed Implementation

[0035] The present application will be further described in detail below with reference to the embodiments.

[0036] Preparation Example 1

[0037] Composite filter material 1

[0038] Alumina powder and pore-forming agent ammonium bicarbonate were mixed at a mass ratio of 75:15 and added to a planetary ball mill. The mixture was dry-milled at 200 r / min for 1 hour with a ball-to-powder ratio of 3:1. Then, 3% (by mass) of polyvinyl alcohol with a molecular weight of 1500, 1% (by mass) of dibutyl phthalate, and 20% (by mass) of anhydrous ethanol were added. The mixture was then wet-milled at 250 r / min for 2 hours, and a homogeneous slurry with a solid content of 60% was collected. Material preparation: Pour the slurry into a mold with a release agent coated on the inner wall, press it under 20 MPa pressure for 5 minutes to form, and obtain a green blank after demolding; place the green blank in a sintering furnace, heat it to 300℃ at a rate of 50℃ / h and hold it for 2 hours, then heat it to 1200℃ at a rate of 80℃ / h and hold it for 3 hours, and then cool it to room temperature at a rate of 50℃ / h; after cooling, clean it with deionized water by ultrasonication, and finally dry it at 100℃ for 4 hours to prepare the composite filter material 1.

[0039] Preparation Example 2

[0040] Composite filter material 2

[0041] Alumina powder and pore-forming agent ammonium bicarbonate were mixed at a mass ratio of 4:1 and added to a planetary ball mill. The mixture was dry-milled at a ball-to-powder ratio of 4:1 at a speed of 250 r / min for 1 hour. Then, polyvinyl alcohol with a molecular weight of 2000 (4% of the total mass of the mixed powder), dibutyl phthalate (2% of the total mass of the mixed powder), and anhydrous ethanol (25% of the total mass of the mixed powder) were added. The mixture was then wet-milled at a speed of 300 r / min for 3 hours, and a uniform slurry with a solid content of 65% was collected. Pour the slurry into a mold with a release agent coated on the inner wall, press it under 25 MPa pressure for 7 minutes to form, and obtain a green blank after demolding. Place the green blank in a sintering furnace, heat it to 350℃ at a rate of 75℃ / h and hold it for 2 hours, then heat it to 1275℃ at a rate of 120℃ / h and hold it for 4 hours, and then cool it to room temperature at a rate of 65℃ / h. After cooling, clean it with deionized water using ultrasound, and finally dry it at 125℃ for 5 hours to prepare the composite filter material 2.

[0042] Preparation Example 3

[0043] Composite filter material 3

[0044] Alumina powder and pore-forming agent ammonium bicarbonate were mixed at a mass ratio of 85:25 and added to a planetary ball mill. The mixture was dry-milled at 300 r / min for 2 hours with a ball-to-powder ratio of 5:1. Then, polyvinyl alcohol with a molecular weight of 2000 (6% of the total mass of the mixed powder), dibutyl phthalate (3% of the total mass of the mixed powder), and anhydrous ethanol (30% of the total mass of the mixed powder) were added. The mixture was then wet-milled at 350 r / min for 4 hours, and a uniform slurry with a solid content of 70% was collected. Pour the slurry into a mold with a release agent coated on the inner wall, press it under 30 MPa pressure for 10 minutes to form a green body, and demold it to obtain a green body. Place the green body in a sintering furnace, heat it to 400℃ at a rate of 100℃ / h and hold it for 3 hours, then heat it to 1350℃ at a rate of 150℃ / h and hold it for 5 hours, and then cool it to room temperature at a rate of 80℃ / h. After cooling, clean it with deionized water using ultrasound, and finally dry it at 150℃ for 6 hours to obtain the composite filter material 3.

[0045] Preparation Example 4

[0046] Composite filter material 4

[0047] TEOS: anhydrous ethanol: deionized water were mixed in a volume ratio of 1:3:0.8 and stirred at 30°C for 15 min. Ammonia was added dropwise to adjust the pH to 8.5, and the mixture was stirred at 350 rpm for 2 h to obtain silica sol. NaHSO₄ was then added... 3： The mass ratio of NaHSO3 to silica sol was 1:10 to 1:20. NaHSO3 was dissolved by ultrasonication and then added dropwise to the silica sol. The mixture was stirred with ultrasonic assistance at 350W for 40 min. 2% of the total mass of silica sol was added to PEG-400. After stirring for 1.5 h, the mixture was aged at room temperature for 24 h, dried and ground to prepare sodium bisulfite-silica composite nanoparticles with a particle size of 50 nm.

[0048] Add 0.5% (by mass) of sodium bisulfite-silica composite nanoparticles (50 nm) to the sodium aluminosilicate sol and ultrasonically disperse at 200 W for 30 min to form a synthesis solution with a solid content of 10%. Place composite filter material 1 in a 5 mol / L nitric acid solution and soak at 60℃ for 2 h. Wash until pH=7, dry at 120℃ for 3 h, and vertically place it into a polytetrafluoroethylene-lined reactor containing the synthesis solution, with a 5 mm gap between the substrate and the liner wall. After sealing the reactor, heat at a rate of 2℃ / min. After heating to 80℃ and holding for 1 hour, the temperature was increased to 100℃ at a rate of 1℃ / min and held for 8 hours, with the pressure inside the reactor maintained at 0.15MPa. After the reaction was completed, the reactor was cooled to room temperature and the substrate was removed. The substrate surface was rinsed three times with 60℃ deionized water to remove unreacted residue, and then dried in an 80℃ oven for 4 hours. After drying, the substrate was calcined in a 400℃ muffle furnace for 2 hours, cooled naturally, and then ultrasonically cleaned with 150W power for 10 minutes. Finally, it was dried in a 120℃ oven for 2 hours to obtain composite filter material 4.

[0049] Preparation Example 5

[0050] Composite filter material 5

[0051] TEOS: anhydrous ethanol: deionized water were mixed at a volume ratio of 1:3:0.8 and stirred at 30°C for 15 min. Ammonia was added dropwise to adjust the pH to 8.5, and the mixture was stirred at 350 r / min for 2 h to obtain silica sol. NaHSO3 was dissolved by ultrasonication at a mass ratio of 1:10 to 1:20 and then added dropwise to the silica sol. The mixture was stirred with ultrasonic assistance at 350 W for 40 min, and 2% (by mass) of PEG-400 (by total mass of silica sol) was added. The mixture was stirred for another 1.5 h, aged at room temperature for 24 h, dried, and ground to prepare sodium bisulfite-silica composite nanoparticles with a particle size of 50 nm. Sodium bisulfite-silica composite nanoparticles with a particle size of 75 nm were added to the sodium aluminosilicate sol at a mass ratio of 0.75% (by total mass of the synthesis solution) and dispersed by ultrasonication at 250 W for 35 min to form a synthesis solution with a solid content of 11%. 2 composite filter materials were taken. The substrate was immersed in a 5 mol / L nitric acid solution at 65℃ for 2.5 h, washed until pH=7, dried at 135℃ for 3.5 h, and then vertically placed in a polytetrafluoroethylene-lined reactor containing the synthesis solution, with a 5 mm gap between the substrate and the liner wall. After sealing the reactor, the temperature was increased to 80℃ at a rate of 2℃ / min and held for 1 h, then increased to 110℃ at a rate of 1℃ / min and held for 9 h, with the pressure inside the reactor maintained at 0.175 MPa. After the reaction, the substrate was cooled to room temperature with the furnace and removed. The surface of the substrate was rinsed three times with 65℃ deionized water to remove unreacted residue, and then dried in an oven at 85℃ for 4.5 h. After drying, the substrate was calcined in a muffle furnace at 425℃ for 2.5 h, naturally cooled, and then ultrasonically cleaned with 175W power for 12.5 min. Finally, it was dried in an oven at 120℃ for 2.5 h to obtain the composite filter material 5.

[0052] Preparation Example 6

[0053] Composite filter material 6

[0054] TEOS: anhydrous ethanol: deionized water were mixed at a volume ratio of 1:3:0.8 and stirred at 30°C for 15 min. Ammonia was added dropwise to adjust the pH to 8.5, and the mixture was stirred at 350 r / min for 2 h to obtain silica sol. NaHSO3 was dissolved by ultrasonication at a mass ratio of 1:10 to 1:20 and then added dropwise to the silica sol. The mixture was stirred with ultrasonic assistance at 350 W for 40 min, and 2% (by mass) of PEG-400 (by total mass of silica sol) was added. The mixture was stirred for another 1.5 h, aged at room temperature for 24 h, dried, and ground to prepare sodium bisulfite-silica composite nanoparticles with a particle size of 50 nm. Sodium bisulfite-silica composite nanoparticles with a particle size of 100 nm (by total mass of the synthesis solution) were added to the sodium aluminosilicate sol and dispersed by ultrasonication at 300 W for 40 min to form a synthesis solution with a solid content of 12%. The composite nanoparticles were then taken... Filter material 3 was placed in a 5 mol / L nitric acid solution and soaked at 70℃ for 3 hours. After washing until pH=7, it was dried at 150℃ for 4 hours and placed vertically in a polytetrafluoroethylene-lined reactor containing the synthesis solution, with a 5 mm gap between the substrate and the liner wall. After sealing the reactor, the temperature was increased to 80℃ at a rate of 2℃ / min and held for 1 hour. Then, the temperature was increased to 120℃ at a rate of 1℃ / min and held for 10 hours, with the pressure inside the reactor maintained at 0.2 MPa. After the reaction was completed, the reactor was cooled to room temperature and the substrate was removed. The substrate surface was rinsed four times with 70℃ deionized water to remove unreacted residue. Then, it was dried in a 90℃ oven for 5 hours. After drying, it was calcined in a 450℃ muffle furnace for 3 hours. After natural cooling, it was ultrasonically cleaned with 200W power for 15 minutes and finally dried in a 120℃ oven for 3 hours to obtain composite filter material 6.

[0055] Preparation Example 7

[0056] Composite filter material 7

[0057] Weigh the raw materials according to the molar ratio of SiO2:Al2O3:Na2O:H2O=10:1:3:100. Dissolve sodium hydroxide in deionized water, and add sodium aluminate and sodium silicate solutions in sequence. Stir mechanically for 40 min to form a uniform gel. Transfer the gel to a polytetrafluoroethylene-lined reactor, seal it, and place it in a 90℃ oven for static crystallization for 8 h. After crystallization, remove the reactor and allow it to cool naturally to room temperature. Transfer the product to a centrifuge tube and centrifuge at 10000 r / min for 15 min. Discard the supernatant. Resuspend the precipitate in deionized water and repeat the centrifugation and washing process 4 times. Add the washed seed crystals to deionized water and disperse them ultrasonically at 300 W for 30 min to obtain a FAU seed crystal suspension.

[0058] Take a 0.3 mol / L sodium silicate solution with pH=9 and immerse the composite filter material 4 at 60℃ for 1 h; then use 0.1 wt% FAU seed suspension (seed particle size 200-300 nm) to coat the substrate at a rate of 5 mm / s and dry at 100℃ for 1.5 h to obtain the pretreated substrate. A precursor sol was prepared by mixing silica sol, sodium aluminate, and tetrapropylammonium hydroxide in a molar ratio of SiO2:Al2O3:Na2O:tetrapropylammonium hydroxide:H2O = 10:1:2:3:180. 0.3% (by weight) of sodium bisulfite-silica particles (prepared in Preparation Example 6) were added to the precursor sol, and the mixture was ultrasonically dispersed at 250 W for 40 min to obtain a dispersion with a 12% solid content. The pretreated substrate was immersed in the dispersion and kept at 110°C for 6 h at 0.12 MPa. After cooling, it was calcined at 500°C for 3 h, then ultrasonically cleaned with deionized water at 80°C at 180 W for 15 min, and finally dried at 110°C for 3 h to obtain the composite filter material 7.

[0059] Preparation Example 8

[0060] Composite filter material 8

[0061] Weigh the raw materials according to the molar ratio of SiO2:Al2O3:Na2O:H2O = 10:1:3:100. Dissolve sodium hydroxide in deionized water, and add sodium aluminate and sodium silicate solutions sequentially. Stir mechanically for 40 min to form a uniform gel. Transfer the gel to a polytetrafluoroethylene-lined reactor, seal it, and place it in a 90℃ oven for static crystallization for 8 h. After crystallization, remove the reactor and allow it to cool naturally to room temperature. Transfer the product to centrifuge tubes, centrifuge at 10000 r / min for 15 min, and discard the supernatant. The precipitate was resuspended in deionized water and washed by centrifugation four times. The washed seed precipitate was added to deionized water and ultrasonically dispersed at 300W for 30 minutes to obtain FAU seed suspension. The composite filter material 5 was immersed in 0.55mol / L sodium silicate solution at pH=9 for 1.5h at 65℃. Then, the substrate was coated with 0.2wt% FAU seed suspension (seed particle size 200-300nm) at a rate of 6.5mm / s and dried at 110℃ for 2h to obtain pretreated substrate. A precursor sol was prepared by mixing silica sol, sodium aluminate, and tetrapropylammonium hydroxide in a molar ratio of SiO2:Al2O3:Na2O:tetrapropylammonium hydroxide:H2O = 10:1:2.5:3.5:200. 0.55% by weight of sodium bisulfite-silica particles (prepared in Preparation Example 6) were added to the precursor sol, and the mixture was ultrasonically dispersed at 300W for 50 min to obtain a dispersion with a solid content of 13.5%. The pretreated substrate was immersed in the dispersion and kept at 110℃ for 7 h under 0.15 MPa. After cooling, it was calcined at 525℃ for 4 h, then ultrasonically cleaned with deionized water at 85℃ at 215W for 20 min, and finally dried at 120℃ for 4 h to obtain the composite filter material 8.

[0062] Preparation Example 9

[0063] Composite filter material 9

[0064] Weigh the raw materials according to the molar ratio of SiO2:Al2O3:Na2O:H2O = 10:1:3:100. Dissolve sodium hydroxide in deionized water, and add sodium aluminate and sodium silicate solutions sequentially. Stir mechanically for 40 min to form a uniform gel. Transfer the gel to a polytetrafluoroethylene-lined reactor, seal it, and place it in a 90℃ oven for static crystallization for 8 h. After crystallization, remove the reactor and allow it to cool naturally to room temperature. Transfer the product to centrifuge tubes, centrifuge at 10000 r / min for 15 min, and discard the supernatant. The precipitate was resuspended in deionized water and washed by centrifugation four times. The washed seed precipitate was added to deionized water and ultrasonically dispersed at 300W for 30 minutes to obtain FAU seed suspension. The composite filter material 6 was immersed in 0.8mol / L sodium silicate solution at pH=9 for 2 hours at 70℃. Then, the substrate was coated with 0.3wt% FAU seed suspension (seed particle size 200-300nm) at a rate of 8mm / s and dried at 120℃ for 2.5 hours to obtain pretreated substrate. A precursor sol was prepared by mixing silica sol, sodium aluminate, and tetrapropylammonium hydroxide in a molar ratio of SiO2:Al2O3:Na2O:tetrapropylammonium hydroxide:H2O = 10:1:3:4:220. 0.8% (by weight) of sodium bisulfite-silica particles (prepared in Preparation Example 6) were added to the precursor sol, and the mixture was ultrasonically dispersed at 350W for 60 min to obtain a dispersion with a 15% solid content. The pretreated substrate was immersed in the dispersion and kept at 110℃ for 8 h at 0.18 MPa. After cooling, it was calcined at 550℃ for 5 h, then ultrasonically cleaned with deionized water at 90℃ at 250W for 25 min, and finally dried at 130℃ for 5 h to obtain the composite filter material 9.

[0065] Preparation Example 10

[0066] Activated carbon fiber modified by phosphoric acid impregnation: Take a sample with a specific surface area of ​​1500 m² 2 / g of activated carbon fiber is soaked in a 15mol / L phosphoric acid solution, stirred at 70℃ for 5h, then washed with deionized water until the pH of the soaking solution is 7, and dried at 150℃ for 3h to obtain activated carbon fiber modified by phosphoric acid soaking.

[0067] Example 1

[0068] A method for preparing chromatographically pure methanol includes the following preparation steps:

[0069] S1. Pre-adsorption treatment: A three-stage series adsorption column is used as the pre-adsorption device. Each adsorption column is filled with phosphoric acid modified activated carbon fiber. Industrial grade methanol is introduced into the three-stage adsorption column at a flow rate of 300 mL / min. The adsorption temperature is controlled at 25℃. During the adsorption process, samples are taken every hour. When the olefin content in the effluent is ≥0.1 ppm, the adsorption column packing is replaced. The adsorbed methanol is transferred to a reaction vessel, and potassium hydroxide powder is added at a ratio of 12% of the methanol mass. The mixture is stirred and heated to 65℃, and then kept under reflux for 3 hours for alkaline hydrolysis.

[0070] S2. Secondary Purification: The methanol material after alkaline hydrolysis is preheated to 80℃ and introduced into composite filter material 1 through a metering pump at a flow rate of 150mL / min, while controlling the operating pressure inside the component to 0.3MPa. After secondary purification, a sample is taken, and the total impurity content is ≤0.1ppm and the 210nm ultraviolet transmittance is ≥35% before it can enter the distillation stage. If the standards are not met, the filtration flow rate is adjusted or the composite filter material is replaced.

[0071] S3. Distillation and Impurity Removal: The methanol material after secondary purification is placed in a distillation column. The distillation and impurity removal parameters are adjusted as follows: 60 trays, a 3m high packed section in the upper part, and a 2m high plate section in the lower part; control the bottom temperature at 70℃, the top temperature at 65℃, and the reflux ratio at 5:1; remove the fraction before the top of the column, collect the middle fraction, and take samples every 30 minutes to test the middle fraction. The requirements are: GC purity ≥99.995%, moisture content ≤0.02%, and 250~800nm ​​UV transmittance ≥95%. Unqualified fractions are returned to the bottom of the column for re-distillation.

[0072] S4. Storage and processing: After filtering the collected middle fraction through a PVDF filter with a pore size of 0.22μm, it is filled under nitrogen protection and stored in a container protected by inert gas to prepare chromatographically pure methanol.

[0073] Example 2

[0074] A method for preparing chromatographically pure methanol includes the following preparation steps:

[0075] S1. Pre-adsorption treatment: A three-stage series adsorption column is used as the pre-adsorption device. Each adsorption column is filled with phosphoric acid modified activated carbon fiber. Industrial grade methanol is introduced into the three-stage adsorption column at a flow rate of 400 mL / min. The adsorption temperature is controlled at 30℃. During the adsorption process, samples are taken every hour. When the olefin content in the effluent is ≥0.1 ppm, the adsorption column packing is replaced. The adsorbed methanol is transferred to a reaction vessel, and potassium hydroxide powder is added at a ratio of 13.5% of the methanol mass. The mixture is stirred and heated to 67.5℃, and then kept under reflux for 4 hours for alkaline hydrolysis.

[0076] S2. Secondary Purification: The methanol material after alkaline hydrolysis is preheated to 85℃ and introduced into composite filter material 1 through a metering pump at a flow rate of 175mL / min, while controlling the operating pressure inside the component to 0.4MPa. After secondary purification, a sample is taken, and the total impurity content is ≤0.1ppm and the 210nm ultraviolet transmittance is ≥35% before it can enter the distillation stage. If the standards are not met, the filtration flow rate is adjusted or the composite filter material is replaced.

[0077] S3. Distillation and Impurity Removal: The methanol material after secondary purification is placed in a distillation column. The distillation and impurity removal parameters are adjusted as follows: 60 trays, a 3m high packed section in the upper section, and a 2m high plate section in the lower section; control the bottom temperature at 72.5℃, the top temperature at 67.5℃, and the reflux ratio at 6.5:1; remove the fraction before the top of the column, collect the middle fraction, and take samples every 30 minutes to test the middle fraction. The requirements are: GC purity ≥99.995%, moisture content ≤0.02%, and 250~800nm ​​UV transmittance ≥95%. Unqualified fractions are returned to the bottom of the column for re-distillation.

[0078] S4. Storage and processing: After filtering the collected middle fraction through a PVDF filter with a pore size of 0.22μm, it is filled under nitrogen protection and stored in a container protected by inert gas to prepare chromatographically pure methanol.

[0079] Example 3

[0080] A method for preparing chromatographically pure methanol includes the following preparation steps:

[0081] S1. Pre-adsorption treatment: A three-stage series adsorption column is used as the pre-adsorption device. Each adsorption column is filled with phosphoric acid modified activated carbon fiber. Industrial grade methanol is introduced into the three-stage adsorption column at a flow rate of 500 mL / min. The adsorption temperature is controlled at 35℃. During the adsorption process, samples are taken every hour. When the olefin content in the effluent is ≥0.1 ppm, the adsorption column packing is replaced. The adsorbed methanol is transferred to a reaction vessel, and potassium hydroxide powder is added at a ratio of 15% of the methanol mass. The mixture is stirred and heated to 70℃, and then kept under reflux for 5 hours for alkaline hydrolysis.

[0082] S2. Secondary Purification: The methanol material after alkaline hydrolysis is preheated to 90℃ and introduced into composite filter material 2 through a metering pump at a flow rate of 200mL / min, while controlling the operating pressure inside the component to 0.5MPa. After secondary purification, a sample is taken, and the total impurity content is ≤0.1ppm and the 210nm ultraviolet transmittance is ≥35% before it can enter the distillation stage. If the standards are not met, the filtration flow rate is adjusted or the composite filter material is replaced.

[0083] S3. Distillation and Impurity Removal: The methanol material after secondary purification is placed in a distillation column. The distillation and impurity removal parameters are adjusted as follows: 60 trays, a 3m high packed section in the upper section, and a 2m high plate section in the lower section; control the bottom temperature at 75℃, the top temperature at 70℃, and the reflux ratio at 8:1; remove the fraction before the top of the column, collect the middle fraction, and take samples every 30 minutes to test the middle fraction. The requirements are: GC purity ≥99.995%, moisture content ≤0.02%, and 250~800nm ​​UV transmittance ≥95%. Unqualified fractions are returned to the bottom of the column for re-distillation.

[0084] S4. Storage and processing: After filtering the collected middle fraction through a PVDF filter with a pore size of 0.22μm, it is filled under nitrogen protection and stored in a container protected by inert gas to prepare chromatographically pure methanol.

[0085] Example 4

[0086] A method for preparing chromatographically pure methanol includes the following preparation steps:

[0087] S1. Pre-adsorption treatment: A three-stage series adsorption column is used as the pre-adsorption device. Each adsorption column is filled with phosphoric acid modified activated carbon fiber. Industrial grade methanol is introduced into the three-stage adsorption column at a flow rate of 400 mL / min. The adsorption temperature is controlled at 30℃. During the adsorption process, samples are taken every hour. When the olefin content in the effluent is ≥0.1 ppm, the adsorption column packing is replaced. The adsorbed methanol is transferred to a reaction vessel, and potassium hydroxide powder is added at a ratio of 13.5% of the methanol mass. The mixture is stirred and heated to 67.5℃, and then kept under reflux for 4 hours for alkaline hydrolysis.

[0088] S2. Secondary Purification: The methanol material after alkaline hydrolysis is preheated to 85℃ and introduced into composite filter material 2 through a metering pump at a flow rate of 175mL / min, while controlling the operating pressure inside the component to 0.4MPa. After secondary purification, a sample is taken, and the total impurity content is ≤0.1ppm and the 210nm ultraviolet transmittance is ≥35% before it can enter the distillation stage. If the standards are not met, the filtration flow rate is adjusted or the composite filter material is replaced.

[0089] S3. Distillation and Impurity Removal: The methanol material after secondary purification is placed in a distillation column. The distillation and impurity removal parameters are adjusted as follows: 60 trays, a 3m high packed section in the upper section, and a 2m high plate section in the lower section; control the bottom temperature at 72.5℃, the top temperature at 67.5℃, and the reflux ratio at 6.5:1; remove the fraction before the top of the column, collect the middle fraction, and take samples every 30 minutes to test the middle fraction. The requirements are: GC purity ≥99.995%, moisture content ≤0.02%, and 250~800nm ​​UV transmittance ≥95%. Unqualified fractions are returned to the bottom of the column for re-distillation.

[0090] S4. Storage and processing: After filtering the collected middle fraction through a PVDF filter with a pore size of 0.22μm, it is filled under nitrogen protection and stored in a container protected by inert gas to prepare chromatographically pure methanol.

[0091] Example 5

[0092] A method for preparing chromatographically pure methanol includes the following preparation steps:

[0093] S1. Pre-adsorption treatment: A three-stage series adsorption column is used as the pre-adsorption device. Each adsorption column is filled with phosphoric acid modified activated carbon fiber. Industrial grade methanol is introduced into the three-stage adsorption column at a flow rate of 400 mL / min. The adsorption temperature is controlled at 30℃. During the adsorption process, samples are taken every hour. When the olefin content in the effluent is ≥0.1 ppm, the adsorption column packing is replaced. The adsorbed methanol is transferred to a reaction vessel, and potassium hydroxide powder is added at a ratio of 13.5% of the methanol mass. The mixture is stirred and heated to 67.5℃, and then kept under reflux for 4 hours for alkaline hydrolysis.

[0094] S2. Secondary Purification: The methanol material after alkaline hydrolysis is preheated to 85℃ and then introduced into the composite filter material 3 through a metering pump at a flow rate of 175mL / min, while controlling the operating pressure inside the component to 0.4MPa. After secondary purification, a sample is taken, and the total impurity content is ≤0.1ppm and the 210nm ultraviolet transmittance is ≥35% before it can enter the distillation stage. If the standards are not met, the filtration flow rate is adjusted or the composite filter material is replaced.

[0095] S3. Distillation and Impurity Removal: The methanol material after secondary purification is placed in a distillation column. The distillation and impurity removal parameters are adjusted as follows: 60 trays, a 3m high packed section in the upper section, and a 2m high plate section in the lower section; control the bottom temperature at 72.5℃, the top temperature at 67.5℃, and the reflux ratio at 6.5:1; remove the fraction before the top of the column, collect the middle fraction, and take samples every 30 minutes to test the middle fraction. The requirements are: GC purity ≥99.995%, moisture content ≤0.02%, and 250~800nm ​​UV transmittance ≥95%. Unqualified fractions are returned to the bottom of the column for re-distillation.

[0096] S4. Storage and processing: After filtering the collected middle fraction through a PVDF filter with a pore size of 0.22μm, it is filled under nitrogen protection and stored in a container protected by inert gas to prepare chromatographically pure methanol.

[0097] Example 6

[0098] A method for preparing chromatographically pure methanol includes the following preparation steps:

[0099] S1. Pre-adsorption treatment: A three-stage series adsorption column is used as the pre-adsorption device. Each adsorption column is filled with phosphoric acid modified activated carbon fiber. Industrial grade methanol is introduced into the three-stage adsorption column at a flow rate of 400 mL / min. The adsorption temperature is controlled at 30℃. During the adsorption process, samples are taken every hour. When the olefin content in the effluent is ≥0.1 ppm, the adsorption column packing is replaced. The adsorbed methanol is transferred to a reaction vessel, and potassium hydroxide powder is added at a ratio of 13.5% of the methanol mass. The mixture is stirred and heated to 67.5℃, and then kept under reflux for 4 hours for alkaline hydrolysis.

[0100] S2. Secondary Purification: The methanol material after alkaline hydrolysis is preheated to 85℃ and then introduced into the composite filter material 4 through a metering pump at a flow rate of 175mL / min, while controlling the operating pressure inside the component to 0.4MPa. After secondary purification, a sample is taken, and the total impurity content is ≤0.1ppm and the 210nm ultraviolet transmittance is ≥35% before it can enter the distillation stage. If the standards are not met, the filtration flow rate is adjusted or the composite filter material is replaced.

[0101] S3. Distillation and Impurity Removal: The methanol material after secondary purification is placed in a distillation column. The distillation and impurity removal parameters are adjusted as follows: 60 trays, a 3m high packed section in the upper section, and a 2m high plate section in the lower section; control the bottom temperature at 72.5℃, the top temperature at 67.5℃, and the reflux ratio at 6.5:1; remove the fraction before the top of the column, collect the middle fraction, and take samples every 30 minutes to test the middle fraction. The requirements are: GC purity ≥99.995%, moisture content ≤0.02%, and 250~800nm ​​UV transmittance ≥95%. Unqualified fractions are returned to the bottom of the column for re-distillation.

[0102] S4. Storage and processing: After filtering the collected middle fraction through a PVDF filter with a pore size of 0.22μm, it is filled under nitrogen protection and stored in a container protected by inert gas to prepare chromatographically pure methanol.

[0103] Example 7

[0104] A method for preparing chromatographically pure methanol includes the following preparation steps:

[0105] S1. Pre-adsorption treatment: A three-stage series adsorption column is used as the pre-adsorption device. Each adsorption column is filled with phosphoric acid modified activated carbon fiber. Industrial grade methanol is introduced into the three-stage adsorption column at a flow rate of 400 mL / min. The adsorption temperature is controlled at 30℃. During the adsorption process, samples are taken every hour. When the olefin content in the effluent is ≥0.1 ppm, the adsorption column packing is replaced. The adsorbed methanol is transferred to a reaction vessel, and potassium hydroxide powder is added at a ratio of 13.5% of the methanol mass. The mixture is stirred and heated to 67.5℃, and then kept under reflux for 4 hours for alkaline hydrolysis.

[0106] S2. Secondary Purification: The methanol material after alkaline hydrolysis is preheated to 85℃ and introduced into the composite filter material 5 through a metering pump at a flow rate of 175mL / min, while controlling the operating pressure inside the component to 0.4MPa. After secondary purification, a sample is taken, and the total impurity content is ≤0.1ppm and the 210nm ultraviolet transmittance is ≥35% before it can enter the distillation stage. If the standards are not met, the filtration flow rate is adjusted or the composite filter material is replaced.

[0107] S3. Distillation and Impurity Removal: The methanol material after secondary purification is placed in a distillation column. The distillation and impurity removal parameters are adjusted as follows: 60 trays, a 3m high packed section in the upper section, and a 2m high plate section in the lower section; control the bottom temperature at 72.5℃, the top temperature at 67.5℃, and the reflux ratio at 6.5:1; remove the fraction before the top of the column, collect the middle fraction, and take samples every 30 minutes to test the middle fraction. The requirements are: GC purity ≥99.995%, moisture content ≤0.02%, and 250~800nm ​​UV transmittance ≥95%. Unqualified fractions are returned to the bottom of the column for re-distillation.

[0108] S4. Storage and Processing: After filtering the collected midstream fraction through a PVDF filter with a pore size of 0.22 μm, it is filled into containers under nitrogen protection and stored in containers protected by inert gas to prepare chromatographically pure methanol. Example 8

[0109] A method for preparing chromatographically pure methanol includes the following preparation steps:

[0110] S1. Pre-adsorption treatment: A three-stage series adsorption column is used as the pre-adsorption device. Each adsorption column is filled with phosphoric acid modified activated carbon fiber. Industrial grade methanol is introduced into the three-stage adsorption column at a flow rate of 400 mL / min. The adsorption temperature is controlled at 30℃. During the adsorption process, samples are taken every hour. When the olefin content in the effluent is ≥0.1 ppm, the adsorption column packing is replaced. The adsorbed methanol is transferred to a reaction vessel, and potassium hydroxide powder is added at a ratio of 13.5% of the methanol mass. The mixture is stirred and heated to 67.5℃, and then kept under reflux for 4 hours for alkaline hydrolysis.

[0111] S2. Secondary Purification: The methanol material after alkaline hydrolysis is preheated to 85℃ and then introduced into the composite filter material 6 through a metering pump at a flow rate of 175mL / min, while controlling the operating pressure inside the component to 0.4MPa. After secondary purification, a sample is taken, and the total impurity content is ≤0.1ppm and the 210nm ultraviolet transmittance is ≥35% before it can enter the distillation stage. If the standards are not met, the filtration flow rate is adjusted or the composite filter material is replaced.

[0112] S3. Distillation and Impurity Removal: The methanol material after secondary purification is placed in a distillation column. The distillation and impurity removal parameters are adjusted as follows: 60 trays, a 3m high packed section in the upper section, and a 2m high plate section in the lower section; control the bottom temperature at 72.5℃, the top temperature at 67.5℃, and the reflux ratio at 6.5:1; remove the fraction before the top of the column, collect the middle fraction, and take samples every 30 minutes to test the middle fraction. The requirements are: GC purity ≥99.995%, moisture content ≤0.02%, and 250~800nm ​​UV transmittance ≥95%. Unqualified fractions are returned to the bottom of the column for re-distillation.

[0113] S4. Storage and Processing: After filtering the collected midstream fraction through a PVDF filter with a pore size of 0.22 μm, it is filled into containers under nitrogen protection and stored in containers protected by inert gas to prepare chromatographically pure methanol. Example 9

[0114] A method for preparing chromatographically pure methanol includes the following preparation steps:

[0115] S1. Pre-adsorption treatment: A three-stage series adsorption column is used as the pre-adsorption device. Each adsorption column is filled with phosphoric acid modified activated carbon fiber. Industrial grade methanol is introduced into the three-stage adsorption column at a flow rate of 400 mL / min. The adsorption temperature is controlled at 30℃. During the adsorption process, samples are taken every hour. When the olefin content in the effluent is ≥0.1 ppm, the adsorption column packing is replaced. The adsorbed methanol is transferred to a reaction vessel, and potassium hydroxide powder is added at a ratio of 13.5% of the methanol mass. The mixture is stirred and heated to 67.5℃, and then kept under reflux for 4 hours for alkaline hydrolysis.

[0116] S2. Secondary Purification: The methanol material after alkaline hydrolysis is preheated to 85℃ and then introduced into the composite filter material 7 through a metering pump at a flow rate of 175mL / min, while controlling the operating pressure inside the component to 0.4MPa. After secondary purification, a sample is taken, and the total impurity content is ≤0.1ppm and the 210nm ultraviolet transmittance is ≥35% before it can enter the distillation stage. If the standards are not met, the filtration flow rate is adjusted or the composite filter material is replaced.

[0117] S3. Distillation and Impurity Removal: The methanol material after secondary purification is placed in a distillation column. The distillation and impurity removal parameters are adjusted as follows: 60 trays, a 3m high packed section in the upper section, and a 2m high plate section in the lower section; control the bottom temperature at 72.5℃, the top temperature at 67.5℃, and the reflux ratio at 6.5:1; remove the fraction before the top of the column, collect the middle fraction, and take samples every 30 minutes to test the middle fraction. The requirements are: GC purity ≥99.995%, moisture content ≤0.02%, and 250~800nm ​​UV transmittance ≥95%. Unqualified fractions are returned to the bottom of the column for re-distillation.

[0118] S4. Storage and Processing: After filtering the collected midstream fraction through a PVDF filter with a pore size of 0.22 μm, it is filled into containers under nitrogen protection and stored in containers protected by inert gas to prepare chromatographically pure methanol. Example 10

[0119] A method for preparing chromatographically pure methanol includes the following preparation steps:

[0120] S1. Pre-adsorption treatment: A three-stage series adsorption column is used as the pre-adsorption device. Each adsorption column is filled with phosphoric acid modified activated carbon fiber. Industrial grade methanol is introduced into the three-stage adsorption column at a flow rate of 400 mL / min. The adsorption temperature is controlled at 30℃. During the adsorption process, samples are taken every hour. When the olefin content in the effluent is ≥0.1 ppm, the adsorption column packing is replaced. The adsorbed methanol is transferred to a reaction vessel, and potassium hydroxide powder is added at a ratio of 13.5% of the methanol mass. The mixture is stirred and heated to 67.5℃, and then kept under reflux for 4 hours for alkaline hydrolysis.

[0121] S2. Secondary Purification: The methanol material after alkaline hydrolysis is preheated to 85℃ and introduced into the composite filter material 8 through a metering pump at a flow rate of 175mL / min, while controlling the operating pressure inside the component to 0.4MPa. After secondary purification, a sample is taken, and the total impurity content is ≤0.1ppm and the 210nm ultraviolet transmittance is ≥35% before it can enter the distillation stage. If the standards are not met, the filtration flow rate is adjusted or the composite filter material is replaced.

[0122] S3. Distillation and Impurity Removal: The methanol material after secondary purification is placed in a distillation column. The distillation and impurity removal parameters are adjusted as follows: 60 trays, a 3m high packed section in the upper section, and a 2m high plate section in the lower section; control the bottom temperature at 72.5℃, the top temperature at 67.5℃, and the reflux ratio at 6.5:1; remove the fraction before the top of the column, collect the middle fraction, and take samples every 30 minutes to test the middle fraction. The requirements are: GC purity ≥99.995%, moisture content ≤0.02%, and 250~800nm ​​UV transmittance ≥95%. Unqualified fractions are returned to the bottom of the column for re-distillation.

[0123] S4. Storage and Processing: After filtering the collected midstream fraction through a PVDF filter with a pore size of 0.22 μm, it is filled into containers under nitrogen protection and stored in containers protected by inert gas to prepare chromatographically pure methanol. Example 11

[0124] A method for preparing chromatographically pure methanol includes the following preparation steps:

[0125] S1. Pre-adsorption treatment: A three-stage series adsorption column is used as the pre-adsorption device. Each adsorption column is filled with phosphoric acid modified activated carbon fiber. Industrial grade methanol is introduced into the three-stage adsorption column at a flow rate of 400 mL / min. The adsorption temperature is controlled at 30℃. During the adsorption process, samples are taken every hour. When the olefin content in the effluent is ≥0.1 ppm, the adsorption column packing is replaced. The adsorbed methanol is transferred to a reaction vessel, and potassium hydroxide powder is added at a ratio of 13.5% of the methanol mass. The mixture is stirred and heated to 67.5℃, and then kept under reflux for 4 hours for alkaline hydrolysis.

[0126] S2. Secondary Purification: The methanol material after alkaline hydrolysis is preheated to 85℃ and then introduced into the composite filter material 9 through a metering pump at a flow rate of 175mL / min, while controlling the operating pressure inside the component to 0.4MPa. After secondary purification, a sample is taken, and the total impurity content is ≤0.1ppm and the 210nm ultraviolet transmittance is ≥35% before it can enter the distillation stage. If the standards are not met, the filtration flow rate is adjusted or the composite filter material is replaced.

[0127] S3. Distillation and Impurity Removal: The methanol material after secondary purification is placed in a distillation column. The distillation and impurity removal parameters are adjusted as follows: 60 trays, a 3m high packed section in the upper section, and a 2m high plate section in the lower section; control the bottom temperature at 72.5℃, the top temperature at 67.5℃, and the reflux ratio at 6.5:1; remove the fraction before the top of the column, collect the middle fraction, and take samples every 30 minutes to test the middle fraction. The requirements are: GC purity ≥99.995%, moisture content ≤0.02%, and 250~800nm ​​UV transmittance ≥95%. Unqualified fractions are returned to the bottom of the column for re-distillation.

[0128] S4. Storage and processing: After filtering the collected middle fraction through a PVDF filter with a pore size of 0.22μm, it is filled under nitrogen protection and stored in a container protected by inert gas to prepare chromatographically pure methanol.

[0129] Performance testing

[0130] GC purity: Gas chromatography (GC-2014, column: HP-5 capillary column, column temperature 50℃ constant temperature, detector FID);

[0131] Moisture content: Karl Fischer coulometric method (AKF-2010V, solvent: methanol-Karl Fischer reagent mixture);

[0132] Olefin content: Gas chromatography-mass spectrometry (GC-MSQP2020, ion monitoring mode selected);

[0133] Aldehyde content (calculated as formaldehyde): High performance liquid chromatography (HPLC-1260, derivatizing agent: 2,4-dinitrophenylhydrazine, detection wavelength 360nm).

[0134] Ester content (calculated as ethyl acetate): Gas chromatography (same as GC purity detection conditions, external standard method for quantification).

[0135] Storage stability (25℃ × 6 months): After storage, the transmittance at 210nm, moisture content, and aldehyde content were measured, and the transmittance retention rate was calculated.

[0136] The results are shown in Table 1 below:

[0137] Table 1 Performance Test Table

[0138]

[0139] By comparing the test results of Examples 1-11 above with those in Table 1, it can be found that:

[0140] The GC purity of methanol refined according to this application is significantly improved, and the moisture content meets the qualified standards and is far superior to industrial grade methanol (purity ≤99.6%), which meets the high purity requirements of chromatographic analysis for mobile phase.

[0141] Based on the technical solutions of Examples 1-3, 4-6 and 7-11, the aldehyde content decreased from 0.008ppm to 0.003ppm, and the 210nm transmittance increased from 35.2% to 39.8%, indicating that the dual-film structure significantly enhances the removal effect of polar impurities.

[0142] The transmittance retention of Examples 9-11 is higher than that of Examples 1-3 because the sulfite active component retained by the double membrane can inhibit methanol oxidation, proving that the design of "integration of purification materials and stabilizers" effectively improves the long-term storage performance of the product.

[0143] The contents of olefins and esters were both ≤0.045ppm, and gradually decreased with the synergistic effect of the entire process of adsorption-alkaline hydrolysis-dual membrane purification. This indicates that the pre-adsorption (modified activated carbon fiber) and alkaline hydrolysis (potassium hydroxide) preliminarily removed non-polar impurities, laying the foundation for subsequent deep purification.

[0144] The present invention has been described in detail above with reference to specific embodiments and exemplary examples; however, these descriptions should not be construed as limiting the present invention. Those skilled in the art will understand that various equivalent substitutions, modifications, or improvements can be made to the technical solutions and embodiments of the present invention without departing from the spirit and scope of the invention, and all such modifications and improvements fall within the scope of the present invention. The scope of protection of the present invention is defined by the appended claims.

[0145] All publications, patent applications, patents, and other references mentioned in this specification are incorporated herein by reference. Unless otherwise defined, all technical and scientific terms used in this specification have the meanings commonly understood by those skilled in the art. In case of conflict, the definitions in this specification shall prevail.

[0146] When this specification uses the prefixes “known to those skilled in the art,” “prior art,” or similar terms to derive materials, substances, methods, steps, apparatus, or components, the objects derived from such prefixes cover those commonly used in the art at the time of this application, but also include those that are not currently commonly used but will become generally recognized in the art as suitable for similar purposes.

[0147] In the context of this specification, except where expressly stated otherwise, any matters or issues not mentioned shall apply directly to those known in the art without any modification.

Claims

1. A method for preparing chromatographically pure methanol, characterized in that, The preparation steps include the following: S1. Pre-adsorption treatment: Select industrial grade methanol and place it in a pre-adsorption device for pre-adsorption treatment and add potassium hydroxide powder. Then, reflux alkaline hydrolysis treatment at 65-70℃ for 3-5 hours. S2. Secondary purification: The methanol material after alkaline hydrolysis is sequentially passed through composite filter material for adsorption and impurity removal, undergoing secondary purification treatment. S3. Distillation and purification: The methanol material after secondary purification is placed in a distillation column, the distillation and purification parameters are adjusted, the top fraction is removed, and the middle fraction is collected. S4. Storage and processing: After the collected middle fraction is filtered through a filter element, it is filled into containers under nitrogen protection and stored in containers under inert gas protection to prepare chromatographically pure methanol.

2. The method for preparing chromatographically pure methanol according to claim 1, characterized in that, The pretreatment adsorption process uses activated carbon fiber modified by phosphate soaking.

3. The method for preparing chromatographically pure methanol according to claim 1, characterized in that, The composite filter material comprises a porous ceramic matrix, a first hydrophilic molecular sieve membrane, and a second FAU-type molecular sieve membrane, which are stacked sequentially from the inside out.

4. The method for preparing chromatographically pure methanol according to claim 3, characterized in that, The porous ceramic matrix is ​​made using the following technical solution: After mixing and grinding alumina powder and ammonium bicarbonate, polyvinyl alcohol and dibutyl phthalate are added, followed by anhydrous ethanol in batches. The mixture is then wet-milled and collected to obtain a slurry. The slurry is placed in a mold, demolded, and sintered. After cooling to room temperature, it is washed and dried to obtain the porous ceramic matrix.

5. The method for preparing chromatographically pure methanol according to claim 3, characterized in that, The first hydrophilic molecular sieve membrane is manufactured using the following technical solution: Sodium aluminosilicate sol was taken and sodium bisulfite-silica composite nanoparticles were added. After ultrasonic dispersion, a synthesis solution was formed. A porous ceramic matrix was placed in the synthesis solution, heated and kept at a constant temperature for reaction, and then washed and dried to prepare the first hydrophilic molecular sieve membrane.

6. The method for preparing chromatographically pure methanol according to claim 5, characterized in that, The second FAU-type molecular sieve membrane is manufactured using the following technical solution: A porous ceramic substrate coated with a first hydrophilic molecular sieve membrane was immersed in a sodium silicate solution. After immersion, it was coated with FAU seed suspension, pulled up and dried to prepare a pretreated substrate. Silica sol, sodium aluminate, tetrapropylammonium hydroxide, sodium bisulfite-silica particles are stirred, mixed, and ultrasonically dispersed. After collecting the dispersion, the pretreated substrate is placed in the dispersion, heated and pressure-treated by programmed temperature rise, cooled to room temperature, calcined, washed and dried to prepare a composite filter material coated with a second FAU type molecular sieve membrane.

7. The method for preparing chromatographically pure methanol according to claim 1, characterized in that, The parameters for the distillation and purification process are as follows: The tower has 60 trays, with a 3m high packed section at the top and a 2m high plate section at the bottom. The bottom temperature is controlled at 70-75℃, the top temperature at 65-70℃, and the reflux ratio is 5-8:

1.

8. The method for preparing chromatographically pure methanol according to claim 1, characterized in that, The adsorption flow rate of the pretreatment adsorption process is 300-500 mL / min.

Images