A method for resource recycling of methanol and vinyl acetate

Abstract

The present application relates to a kind of methanol and vinyl acetate resource recycling method.The method includes the following steps (1) water is added to vinyl acetate and methanol mixture, and then a mixed solution is obtained, the mixed solution is treated using adsorbent, and the adsorbent and the residual liquid adsorbed are obtained;The residual liquid adsorbed is subjected to liquid-liquid separation, and organic phase and aqueous phase are obtained;(2) the adsorbent adsorbed with liquid is subjected to desorption treatment, and methanol recovery liquid is obtained;(3) the organic phase is subjected to distillation treatment, and vinyl acetate recovery liquid is obtained.The present application first adds water to extract vinyl acetate, so that it becomes organic phase, and then adsorbent is added to absorb methanol in aqueous phase system as much as possible, so that the effective separation of methanol and vinyl acetate is realized.The method of the present application is simple and effective, and has important application potential.

Description

Technical Field

[0001] This invention relates to the technical field of resource recycling, and more specifically, to a method for the resource recycling of methanol and vinyl acetate. Background Technology

[0002] Methanol is an important chemical raw material used to manufacture various organic products such as chloromethane, methylamine, and dimethyl sulfate. It is also a raw material for pesticides (insecticides, acaricides) and pharmaceuticals (sulfonamides, streptomycin, etc.), and one of the raw materials for the synthesis of dimethyl terephthalate, methyl methacrylate, and methyl acrylate. The main application of methanol is in the production of formaldehyde, which is used to produce adhesives, primarily in the wood processing industry, and secondarily as a treatment agent for molding compounds, coatings, textiles, and paper.

[0003] Vinyl acetate is also an important chemical raw material, mainly used as a copolymer and polymerizing monomer to produce polyvinyl alcohol, vinyl acetate-ethylene copolymer (EVA), and copolymers of vinyl acetate with vinyl chloride, acrylates, and acrylonitrile. It is used in light industry, textiles, papermaking, and construction as an adhesive, coating, and fiber, and has significant industrial application value.

[0004] C2H4-vinyl alcohol copolymer (EVOH) possesses excellent processability, gas barrier properties, transparency, elasticity, and weather resistance, and is also highly crystallizable, environmentally friendly, and non-toxic. EVOH is generally produced by conventional polymerization methods such as emulsion polymerization, solution polymerization, or suspension polymerization of C2H4 and vinyl acetate (VAC) to form C2H4-VAC copolymer (EVA), followed by alcoholysis reaction under alkaline catalyst. During the EVA solution polymerization process, in order to control the molecular weight, distribution, branching degree, and crystallinity of the EVOH product, the conversion rate of VAC must be strictly controlled (below 60%). Therefore, about 40% of VAC does not participate in the polymerization reaction, necessitating its recycling. Furthermore, the EVA polymerization process generates a large amount of VAC and methanol (CH4O) azeotrope, which is difficult to recover using ordinary distillation. Therefore, during the formation of C2H4-vinyl alcohol copolymer, a large amount of methanol as a solution and unreacted ethylene and vinyl acetate are generated. The unreacted ethylene can be recovered after vacuum flash evaporation, while the unreacted vinyl acetate needs to be recovered through a recycling process.

[0005] Based on the significant industrial value of methanol and vinyl acetate, this invention proposes a method for the resource recovery of methanol and vinyl acetate through adsorption during the production of C2H4-vinyl alcohol copolymer. Summary of the Invention

[0006] To address the problems existing in the prior art, this invention provides a method for the resource recovery of methanol and vinyl acetate. The method of this invention takes into account that vinyl acetate and methanol form an azeotropic system, and the separation of this azeotropic system is an important yet challenging process. To solve this problem, this invention first adds water to extract vinyl acetate, making it an organic phase, and then adds an adsorbent to absorb as much methanol as possible from the aqueous phase, thereby achieving effective separation of methanol and vinyl acetate. The method of this invention is simple and effective, and has significant application potential.

[0007] To address the above problems, one objective of this invention is to provide a method for the resource recovery of methanol and vinyl acetate, comprising the following steps:

[0008] (1) Water is added to a mixture of vinyl acetate and methanol to obtain a mixture. The mixture is then treated with an adsorbent to obtain an adsorbent containing liquid and an adsorbent residue. The adsorbent residue is then subjected to liquid-liquid separation to obtain an organic phase and an aqueous phase.

[0009] (2) The adsorbent containing the liquid is desorbed to obtain methanol recovery liquid;

[0010] (3) The organic phase is distilled to obtain vinyl acetate recovery solution.

[0011] In this invention, because vinyl acetate has poor solubility in water, methanol can be fully dissolved in water through thorough mixing. Vinyl acetate is not easily soluble in water, especially at low temperatures, as this invention has found. Therefore, vinyl acetate becomes the organic phase and floats on the upper layer of the aqueous phase. When treated with an adsorbent, the adsorbent adsorbs methanol and some water in the aqueous phase. Since the composition of the aqueous phase changes after the methanol is absorbed by the adsorbent, it is beneficial to the precipitation of vinyl acetate that was originally soluble in water, thereby improving the extraction efficiency of vinyl acetate and obtaining an organic phase mainly containing vinyl acetate and a mixture mainly containing water and some methanol.

[0012] In the method for resource recovery of methanol and vinyl acetate described in this invention, preferably,

[0013] In step (1),

[0014] The vinyl acetate content in the mixture of vinyl acetate and methanol is 45 wt% to 65 wt% by weight.

[0015] The mass ratio of the vinyl acetate and methanol mixture to the added water is 100:20-40.

[0016] In the method for resource recovery of methanol and vinyl acetate described in this invention, preferably,

[0017] In step (1),

[0018] The adsorbent is a mixture of modified sepiolite and MOF-801.

[0019] In the method for resource recovery of methanol and vinyl acetate described in this invention, preferably,

[0020] In step (1),

[0021] The mass ratio of the mixed solution to the adsorbent is 100:15-30.

[0022] In the method for resource recovery of methanol and vinyl acetate described in this invention, preferably,

[0023] In step (1),

[0024] The temperature for treatment with the adsorbent is -5 to 5℃, and the treatment time is 30 to 40 minutes.

[0025] Liquid-liquid separation is carried out at 10-15℃.

[0026] In the method for resource recovery of methanol and vinyl acetate described in this invention, preferably,

[0027] In step (1),

[0028] The mass ratio of modified sepiolite to MOF-801 (MOF metal-organic framework material) is 1:0.1-0.5.

[0029] In the method for resource recovery of methanol and vinyl acetate described in this invention, preferably,

[0030] In step (1),

[0031] The vinyl acetate and methanol mixture also includes impurities selected from at least one of acetaldehyde, methyl acetate, acetone, and water; preferably, the impurity content in the vinyl acetate and methanol mixture is ≤0.4wt%.

[0032] In the method for resource recovery of methanol and vinyl acetate described in this invention, preferably,

[0033] In step (1),

[0034] The modified sepiolite is prepared by first treating it with acid and then subjecting it to hydrothermal treatment.

[0035] In the method for resource recovery of methanol and vinyl acetate described in this invention, preferably,

[0036] The modified sepiolite is prepared by treating it with 1-2 mol / L octanoic acid at room temperature for 4-8 hours, centrifuging to separate the acid-modified sepiolite, and then hydrothermally treating the acid-modified sepiolite at 180-250 degrees Celsius for 5-8 hours; after centrifugation, it is dried to obtain the modified sepiolite.

[0037] Sepiolite has a large specific surface area and extremely strong adsorption capacity. However, it contains many impurities, so it is essential to activate sepiolite to improve its adsorption performance.

[0038] This invention discovers a synergistic effect between modified sepiolite and MOF-801. When used together, the purity of adsorbed methanol can be significantly improved.

[0039] In the method for resource recovery of methanol and vinyl acetate described in this invention, preferably,

[0040] In step (2), the desorption process is centrifugation.

[0041] In the method for resource recovery of methanol and vinyl acetate described in this invention, preferably,

[0042] In step (3), the distillation process can be carried out according to the existing conventional operating methods and procedures.

[0043] 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.

[0044] 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.

[0045] In the context of this specification, except where expressly stated, any matters or issues not mentioned herein shall apply directly to those known in the art without any modification. Furthermore, any implementation described herein may be freely combined with one or more other implementations described herein, and any resulting technical solutions or concepts shall be considered part of the original disclosure or original record of this invention, and should not be regarded as new content not disclosed or anticipated herein, unless those skilled in the art consider such combination to be clearly unreasonable.

[0046] Beneficial effects:

[0047] This invention first extracts vinyl acetate from the aqueous phase using water, making it an organic phase. Then, an adsorbent is added to absorb as much methanol as possible from the aqueous phase, thereby achieving effective separation of methanol and vinyl acetate. This method is simple, effective, and has significant application potential.

[0048] The method of this invention is simple, and the recovery rate and purity of vinyl acetate are high. Detailed Implementation

[0049] The present invention will now be described in detail with reference to specific embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention are still within the scope of protection of the present invention.

[0050] Raw material source:

[0051] Sepiolite was purchased from Chunlei Insulation Materials Factory in Jingxing County.

[0052] Preparation Example 1

[0053] Preparation of modified sepiolite: After treatment with 1.5 mol / L octanoic acid at room temperature for 6 hours, the acid-modified sepiolite was separated by centrifugation. The acid-modified sepiolite was then hydrothermally treated at 200 degrees Celsius for 7 hours. After centrifugation, it was dried to obtain modified sepiolite.

[0054] Preparation of adsorbent:

[0055] Modified sepiolite and MOF-801 were mixed evenly at a mass ratio of 1:0.3 to obtain the adsorbent.

[0056] Preparation Example 2

[0057] Preparation of modified sepiolite: After treatment with 2 mol / L octanoic acid at room temperature for 4 hours, the acid-modified sepiolite was separated by centrifugation. The acid-modified sepiolite was then hydrothermally treated at 250 degrees Celsius for 5 hours. After centrifugation, it was dried to obtain modified sepiolite.

[0058] Preparation of adsorbent:

[0059] Modified sepiolite and MOF-801 were mixed evenly at a mass ratio of 1:0.3 to obtain the adsorbent.

[0060] Preparation Example 3

[0061] It adopts the same preparation method as Preparation Example 1, except that the modified sepiolite and MOF-801 are mixed evenly at a mass ratio of 1:0.1 to obtain the adsorbent.

[0062] Preparation Example 4

[0063] It adopts the same preparation method as Preparation Example 1, except that the modified sepiolite and MOF-801 are mixed evenly at a mass ratio of 1:0.5 to obtain the adsorbent.

[0064] Example 1

[0065] A method for the resource recovery of methanol and vinyl acetate includes the following steps:

[0066] (1) Add 30g of water to 100g of a mixture of vinyl acetate and methanol (44.7wt% methanol, 55wt% vinyl acetate, 0.3wt% impurities, which are water, acetaldehyde, acetone, and methyl acetate), shake vigorously to mix evenly, and obtain a mixture. Treat the mixture with the adsorbent of Preparation Example 1, wherein the mass ratio of the mixture to the adsorbent is 100:20; the temperature of the adsorbent treatment is 0℃, and the treatment time is 30 minutes; an adsorbent that mainly adsorbs methanol and water and an adsorption residue (including water, some methanol, a small amount of vinyl acetate, and trace impurities) are obtained; after the adsorption residue is allowed to stand for 5 minutes, liquid-liquid separation is performed at 10℃ to obtain an organic phase and an aqueous phase.

[0067] In this invention, because vinyl acetate has poor solubility in water, methanol can be fully dissolved in water through thorough mixing. Vinyl acetate is not easily soluble in water, especially at low temperatures, as this invention has found. Therefore, vinyl acetate becomes the organic phase and floats on the upper layer of the aqueous phase. When treated with an adsorbent, the adsorbent adsorbs methanol and some water in the aqueous phase. Since the composition of the aqueous phase changes after the methanol is absorbed by the adsorbent, it is beneficial to the precipitation of vinyl acetate that was originally soluble in water, thereby improving the extraction efficiency of vinyl acetate and obtaining an organic phase mainly containing vinyl acetate and a mixture mainly containing water and some methanol.

[0068] (2) The adsorbent containing the liquid is centrifuged to desorb it, and methanol recovery liquid is obtained.

[0069] (3) The organic phase is distilled to obtain vinyl acetate recovery solution.

[0070] Example 2

[0071] It uses essentially the same method as Example 1, except that the adsorbent was prepared in Preparation Example 2.

[0072] Example 3

[0073] It uses essentially the same method as Example 1, except that the adsorbent was prepared in Preparation Example 3.

[0074] Example 4

[0075] It uses essentially the same method as Example 1, except that the adsorbent was prepared in Preparation Example 4.

[0076] Example 5

[0077] It uses a method that is basically the same as that in Example 1, except that the mass ratio of the mixture to the adsorbent is 100:15.

[0078] Example 6

[0079] It uses a method that is basically the same as that in Example 1, except that the mass ratio of the mixture to the adsorbent is 100:30.

[0080] Comparative Example 1

[0081] It uses a method that is basically the same as that in Example 1, except that the adsorbent is modified sepiolite.

[0082] Comparative Example 2

[0083] It uses a method that is basically the same as that in Example 1, except that the adsorbent is MOF-801 throughout.

[0084] The purity of the methanol recovery solution and vinyl acetate recovery solution prepared in the above examples and comparative examples was tested, and the specific results are shown in Table 1.

[0085] Table 1

[0086]

[0087] The results above demonstrate that the method of this invention can effectively separate methanol and vinyl acetate with a high yield, exhibiting significant application value. The methanol recovery solution from this invention can be further purified for use as needed.

[0088] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

[0089] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

Claims

1. A method for the resource recovery of methanol and vinyl acetate, comprising the following steps: (1) Water is added to a mixture of vinyl acetate and methanol to obtain a mixture. The mixture is then treated with an adsorbent to obtain an adsorbent containing liquid and an adsorbent residue. The adsorbent residue is then separated into an organic phase and an aqueous phase. The temperature of the adsorbent treatment is -5 to 5℃, and the treatment time is 30 to 40 minutes. The adsorbent is a mixture of modified sepiolite and MOF-801. The mass ratio of modified sepiolite to MOF-801 is 1:0.1 to 0.

5. The modified sepiolite is prepared by first treating it with acid and then performing hydrothermal treatment. (2) The adsorbent containing the liquid is desorbed to obtain methanol recovery liquid; (3) The organic phase is distilled to obtain vinyl acetate recovery solution.

2. The method for resource recovery of methanol and vinyl acetate according to claim 1, characterized in that: In step (1), The vinyl acetate content in the mixture of vinyl acetate and methanol is 45 wt% to 65 wt% by weight. The mass ratio of the vinyl acetate and methanol mixture to the added water is 100:20-40.

3. The method for resource recovery of methanol and vinyl acetate according to claim 1, characterized in that: In step (1), The mass ratio of the mixed solution to the adsorbent is 100:15-30.

4. The method for resource recovery of methanol and vinyl acetate according to claim 1, characterized in that... Liquid-liquid separation is carried out at 10-15℃.

5. The method for resource recovery of methanol and vinyl acetate according to claim 1, characterized in that: In step (1), The mixture of vinyl acetate and methanol also includes impurities selected from at least one of acetaldehyde, methyl acetate, acetone, and water.

6. The method for resource recovery of methanol and vinyl acetate according to claim 5, characterized in that: The impurity content in the mixture of vinyl acetate and methanol is ≤0.4wt%.

7. The method for resource recovery of methanol and vinyl acetate according to claim 1, characterized in that: The preparation method of modified sepiolite is as follows: after treating with 1-2 mol / L octanoic acid at room temperature for 4-8 hours, the acid-modified sepiolite is separated by centrifugation, and the acid-modified sepiolite is hydrothermally treated at 180-250 degrees Celsius for 5-8 hours. After centrifugation, the modified sepiolite was dried to obtain the modified sepiolite.

8. The method for resource recovery of methanol and vinyl acetate according to claim 1, characterized in that: In step (2), the desorption process is centrifugation.

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