A method for separating and purifying vinyl acetate

Abstract

The application discloses a method for separating and purifying vinyl acetate, and uses a cucurbituril [6] channel type crystal material as an adsorbent to selectively adsorb acetaldehyde in a vinyl acetate mixed solution, so as to realize separation and purification of the vinyl acetate; and a structural formula of the cucurbituril [6] channel type crystal material is as follows: The separation process of the application is simple in operation, low in equipment requirement, and excellent in separation effect; the separation process does not need rectification operation, is low in energy consumption, saves energy, is low in purification cost, and is high in stability of the used material and reusability.

Description

Technical Field

[0001] This invention relates to the field of chemical engineering technology, and specifically to a method for the separation and purification of vinyl acetate. Background Technology

[0002] With social development and economic progress, industry is gradually shifting from rough processing to precision manufacturing, leading to a growing demand for high-purity industrial raw materials. However, obtaining high-purity raw materials is often a complex process involving significant energy consumption and high costs. Even then, the target purity is sometimes not achieved. Removing trace amounts of impurities from products remains a challenging task. Furthermore, the requirements for ultra-clean, high-purity (VLSD) reagents are constantly increasing in the manufacturing processes of large-scale integrated circuits (ICs) and high-end semiconductor devices. Vinyl acetate, as an important basic chemical raw material, is widely used in the production of polyvinyl acetate, polyvinyl alcohol, adhesives, coatings, ethylene copolymers, and a range of other important chemical and fiber products. Among these, high-purity vinyl acetate (VAC) with low impurity content is in increasing demand in electronic chemicals.

[0003] Vinyl acetate produced by the gas-phase oxidation method using ethylene and acetic acid as raw materials contains trace amounts of impurities such as methyl acetate, ethyl acetate, acetaldehyde, and benzene, as well as unreacted raw materials. In ordinary distillation columns, it is difficult to completely separate vinyl acetate from unreacted raw materials and impurities; a single distillation is insufficient to obtain a high-purity vinyl acetate product. Obtaining high-purity vinyl acetate requires multiple distillations, consuming more time and energy, and employing meticulous operations to achieve a more refined purification process.

[0004] Patent document CN 104030921 B discloses a method for separating vinyl acetate. This patent uses a partitioned-wall distillation technique to replace the original distillation technique, achieving a separation effect that meets or exceeds the purity of the original process, while reducing total energy consumption by 15-35%, thus saving energy and equipment investment to a certain extent. Patent CN 107011172 A discloses the purification of vinyl acetate using a partitioned-wall tower, further optimizing the purification process and reducing process energy consumption.

[0005] Cucurbitauride, as a fourth-generation macrocyclic host, has been extensively studied. Cucurbitauride is insoluble in most organic solvents, has high recognition performance for guests, and has good chemical and thermal stability. In this invention, cucurbitauride[6] porous crystal material is used as an adsorption separation material for the separation and purification of vinyl acetate.

[0006] Applying cucurbita[6] porous crystal material to the adsorption and separation purification of vinyl acetate will greatly reduce production costs and improve product purity. The cucurbita[6] porous crystal material has good thermal stability, low energy consumption in the adsorption and separation process, and no desorbent is required in the desorption process. Summary of the Invention

[0007] In view of the shortcomings in this field, and the defects in obtaining high-purity vinyl acetate such as complex operation process, high labor cost and high energy consumption, this invention provides a method for separating and purifying vinyl acetate.

[0008] The method for separating and purifying vinyl acetate provided by the present invention utilizes the property of cucurbita[6] channel-type crystal material to selectively adsorb acetaldehyde impurities in vinyl acetate mixed solution to achieve the separation and purification of vinyl acetate.

[0009] The method for separating and purifying vinyl acetate provided by the present invention has the advantages of low energy consumption and simple operation process. Furthermore, the cucurbita[6] channel crystal material used in the method has high stability and can be reused after desorption and regeneration.

[0010] In a first aspect, the present invention provides a method for separating and purifying vinyl acetate.

[0011] A method for separating and purifying vinyl acetate, using cucurbita[6] porous crystal material as an adsorbent to selectively adsorb acetaldehyde impurities in a mixed solution of vinyl acetate, thereby achieving the separation and purification of vinyl acetate;

[0012] The structural formula of the cucurbituril[6] channel-type crystal material is as follows:

[0013]

[0014] The cucurbita[6] channel-type crystal material (CAS No.: 80262-44-8) described in this invention was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0015] The inventive concept of this invention lies in:

[0016] In the method for separating and purifying vinyl acetate, the cucurbita[6] porous crystal material can selectively adsorb impurities in the vinyl acetate mixture solution, wherein the impurity is acetaldehyde. Since the impurities in the mixture solution differ from vinyl acetate in molecular structure and size, the cucurbita[6] porous crystal material in the separation method readily forms a host-guest complex with the impurities. In this host-guest complex, the cucurbita[6] porous crystal material is the host, and the acetaldehyde impurity is the guest. However, the cucurbita[6] porous crystal material is difficult to form a host-guest complex with vinyl acetate. Therefore, in the method for separating and purifying vinyl acetate, the cucurbita[6] porous crystal material can selectively adsorb acetaldehyde impurities in the vinyl acetate mixture solution and exhibits excellent selectivity. The structural diagrams of the cucurbita[6] porous crystal material before and after adsorbing acetaldehyde impurities are shown below. Figure 1 As shown.

[0017] The present invention also provides a more specific method for separating and purifying the vinyl acetate.

[0018] The specific method for separating and purifying vinyl acetate is as follows:

[0019] The cucurbita[6] channel-type crystal material is placed in a mixed solution containing the acetaldehyde impurity and vinyl acetate at a temperature not exceeding 80°C.

[0020] In the separation and purification method, the adsorption time varies with the sample amount, adsorption temperature, and the proportion of the impurities in the mixed solution.

[0021] In the separation and purification method, preferably, the adsorption temperature is 4–60°C.

[0022] During the adsorption process, the cucurbita[6] porous crystal material maintains its original crystal form. The acetaldehyde impurity in the mixed solution forms a host-guest complex with the cucurbita[6] porous crystal material. In this host-guest complex, the cucurbita[6] porous crystal material is the host, and the impurity is the guest.

[0023] The cucurbita[6] porous crystal material described above needs to be activated before separation and purification. Preferably, the activation specifically involves heating the cucurbita[6] porous crystal material at 40–180°C for 4–12 hours. The activated cucurbita[6] porous crystal material can be directly used for the separation and purification of vinyl acetate.

[0024] Preferably, the method for separating and purifying vinyl acetate further includes the removal of the mixture adsorbed on the surface of the adsorbent after the adsorption separation is completed.

[0025] Further preferably, the method for removing the mixture adsorbed on the surface of the adsorbent is to air-dry the cucurbita[6] porous crystal material at room temperature. The air-drying time is adjusted according to the amount of sample.

[0026] At room temperature, the host and guest compounds can exist stably, while the surface-adsorbed mixture can be gradually removed. By removing the mixture adhering to the adsorbent surface, the selectivity of the adsorbent can be better calibrated; by removing the surface-adsorbed mixture, acetaldehyde impurities are concentrated.

[0027] Preferably, the method for separating and purifying vinyl acetate further includes regenerating the adsorbent after the adsorption separation is completed.

[0028] Further preferably, the regeneration method of the adsorbent is as follows: under vacuum or inert atmosphere conditions, the cucurbita[6] porous crystal material is heated to 40-100°C. The heating time is not less than 1 hour and is adjusted according to the sample amount.

[0029] Under conditions of 40–100°C, the host-guest complex formed by the acetaldehyde impurity and the cucurbita[6] porous crystal material is unstable. After heating to the above desorption temperature, it will gradually de-complex, and the adsorbed impurity will be gradually released. The cucurbita[6] porous crystal material is stable at the above desorption temperature. After desorption, the regenerated cucurbita[6] porous crystal material is obtained, which can be used to further separate and purify mixed solutions containing acetaldehyde impurities and vinyl acetate.

[0030] In a second aspect, the present invention also provides the application of cucurbituril[6] porous crystal material as an adsorbent in the separation and purification of vinyl acetate.

[0031] In the application of the cucurbita[6] porous crystal material as an adsorbent in the separation and purification of vinyl acetate, the cucurbita[6] porous crystal material is used as an adsorbent to selectively adsorb acetaldehyde impurities in the vinyl acetate mixed solution, thereby achieving the separation and purification of vinyl acetate.

[0032] The structural formula of the cucurbituril[6] channel-type crystal material is as follows:

[0033]

[0034] The impurities include acetaldehyde.

[0035] Compared with the prior art, the main advantages of this invention are at least as follows:

[0036] (1) The method for separating and purifying vinyl acetate provided by the present invention utilizes the property of cucurbita[6] channel-type crystal material to selectively adsorb acetaldehyde impurities in vinyl acetate mixed solution to achieve the separation and purification of vinyl acetate. The separation process of the vinyl acetate separation method is simple to operate and has low equipment requirements.

[0037] (2) The method for separating and purifying vinyl acetate provided by the present invention has the advantages of low energy consumption and energy saving compared with the separation and purification method that requires distillation operation, which greatly reduces the purification cost of vinyl acetate.

[0038] (3) The cucurbita[6] channel crystal material used in this invention has high stability and can be desorbed and regenerated for use; the activation operation is simple and avoids the lengthy and cumbersome solvent exchange.

[0039] (4) The cucurbita[6] channel-type crystal material used in this invention exhibits excellent selectivity in the selective adsorption of acetaldehyde impurities in vinyl acetate mixed solution.

[0040] (5) The innovation of this invention is also reflected in the fact that the cucurbituril[6] material used is a cucurbituril[6] pore-type crystal material. The cucurbituril[6] pore-type crystal material maintains a high degree of stability of its crystal form during the adsorption process, exhibiting excellent adsorption energy absorption and cycle performance, so that it can be better applied to separation adsorption. Attached Figure Description

[0041] Figure 1 The structural diagram of cucurbita[6] porous crystal material before and after adsorption of acetaldehyde;

[0042] Figure 2 This is a headspace gas chromatography characterization result of industrial vinyl acetate obtained in Example 2;

[0043] Figure 3 The image shows the headspace gas chromatography characterization results of the cucurbituril[6] pore-type crystal material after solid-liquid adsorption separation of industrial vinyl acetate solution as measured in Example 2.

[0044] Figure 4 The X-ray powder diffraction pattern of the cucurbita[6] channel-type crystal material obtained in Example 4 before and after immersion in industrial vinyl acetate for 7 days is shown. Detailed Implementation

[0045] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Operating methods not specifically specified in the following embodiments are generally performed under conventional conditions or as recommended by the manufacturer.

[0046] The porous crystalline cucurbita[6] crystal material used in the specific implementation is an existing material, CAS No.: 80262-44-8, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0047] Example 1

[0048] Activation of cucurbituril[6] channel-type crystal materials:

[0049] The purchased cucurbita[6] porous crystal material was heated at 120°C for 5 hours to obtain activated cucurbita[6] porous crystal material.

[0050] Example 2

[0051] Adsorption experiment of cucurbituril[6] porous crystal material:

[0052] The activated cucurbita[6] channel-type crystal material from Example 1 was used to analyze the impurity content of industrial vinyl acetate (gas chromatography analysis results are as follows). Figure 2(As shown in Table 1) Adsorption of impurities in the liquid phase: Take a 20mL culture bottle, add 1mL of industrial vinyl acetate, take 30mg of cucurbita[6] channel crystal material and place it in the culture bottle, seal it, place it at 25℃ for 48 hours, and air dry the obtained powder.

[0053] The cucurbita[6] channel crystal material, after being placed in the industrial vinyl acetate solution containing acetaldehyde impurities for a period of time, was characterized by headspace gas chromatography.

[0054] The product characterization data measured in this embodiment are as follows:

[0055] The results of headspace gas chromatography are as follows Figure 3 As shown in Table 2, the area of ​​the integral peak after processing by computer software is shown in Table 2.

[0056] Table 1. Content of acetaldehyde impurities relative to vinyl acetate in industrial vinyl acetate

[0057]

[0058] Table 2. Content of acetaldehyde impurities relative to vinyl acetate in cucurbituril[6] channel-type crystal materials

[0059]

[0060] Data shows that cucurbita[6] channel-type crystal material can selectively enrich trace amounts of acetaldehyde impurities in concentrated vinyl acetate samples, with an enrichment factor of up to 88 times.

[0061] Example 3

[0062] Regeneration experiment of cucurbituril[6] channel-type crystal material:

[0063] Regeneration experiment of cucurbita[6] pore-type crystal material after solid-liquid phase adsorption of impurities in industrial vinyl acetate solution in Example 2: 200 mg of the cucurbita[6] pore-type crystal material was taken and heated in a vacuum oven at 100°C for 2 hours. The resulting sample was recorded as Q[6]-CH-D.

[0064] The cucurbita[6] channel-type crystal material obtained from the regeneration experiment was characterized.

[0065] The product characterization data measured in this embodiment are as follows:

[0066] Q[6]-CH-D, 1 H NMR(400MHz,D2O,298K,ppm)δ5.65(d,12H),5.53(s,12H),4.22(d,12H)

[0067] exist 1The H NMR spectrum showed no hydrogen atom signals from any other impurities besides the hydrogen atom signals of the cucurbituril[6] porous crystal material. This indicates that the guest molecule (impurity acetaldehyde) has been completely released, and that the cucurbituril[6] porous crystal material has completed desorption and regeneration.

[0068] Example 4

[0069] Stability evaluation of cucurbituril[6] channel-type crystal materials:

[0070] X-ray powder diffraction was performed on the pore-type crystal material of cucurbita[6].

[0071] Then, 200 mg of the activated cucurbita[6] channel crystal material from Example 1 was placed in 20 mL of industrial vinyl acetate solution containing impurities (Test results of Example 1: relative content of acetaldehyde impurities 0.00732%), and after soaking for 7 days, the cucurbita[6] channel crystal material was taken out and the X-ray powder diffraction pattern was measured again.

[0072] The X-ray powder diffraction patterns of the cucurbituril[6] channel-type crystal material obtained in this embodiment before and after immersion in industrial vinyl acetate for 7 days are as follows: Figure 4 As shown.

[0073] X-ray powder diffraction results showed that vinyl acetate and impurities did not affect the phase structure of the cucurbita[6] channel-type crystal material, and maintained its channel structure characteristics. That is, this example shows that the crystal material can be immersed in the working environment for a long time without affecting the structure of the crystal material, thus ensuring the performance of the material's adsorption stability.

[0074] Example 5

[0075] Reuse of cucurbita[6] porous crystal material: 30 mg of regenerated cucurbita[6] porous crystal material was used to repeat the experimental methods of Examples 2 and 3 for adsorbent regeneration and adsorption.

[0076] The results of headspace gas chromatography show that, as shown in Table 3, the repeated activation and adsorption of cucurbituril[6] channel crystal material can enrich acetaldehyde. Compared with the adsorbed industrial vinyl acetate solution (test results of Example 1: relative content of acetaldehyde impurities 0.00732%), the enrichment factor is between 30 and 88 times. Moreover, the enrichment performance is still excellent after repeated recycling 5 times.

[0077] Table 3. Content of acetaldehyde impurities relative to vinyl acetate in cucurbituril[6] porous crystalline materials

[0078]

[0079]

[0080] Furthermore, it should be understood that after reading the above description of the present invention, those skilled in the art can make various alterations or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims.

Claims

1. A method for separating and purifying vinyl acetate, characterized in that, Using cucurbita[6] porous crystal material as an adsorbent, acetaldehyde impurities in vinyl acetate mixed solution are selectively adsorbed to achieve the separation and purification of vinyl acetate; The structural formula of the cucurbituril[6] channel-type crystal material is as follows: The separation and purification method is as follows: the cucurbita[6] channel-type crystal material is placed in a mixed solution containing acetaldehyde impurities and vinyl acetate, and the temperature is not higher than 80°C; Before the cucurbituril[6] channel-type crystal material is used for separation and purification, it shall be activated as follows: the cucurbituril[6] channel-type crystal material shall be heated at 40-180℃ for 4-12 hours.

2. The method for separating and purifying vinyl acetate according to claim 1, characterized in that, The cucurbita[6] channel-type crystal material, CAS No.: 80262-44-8, was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

3. The method for separating and purifying vinyl acetate according to claim 1, characterized in that, The temperature is 4–60°C.

4. The method for separating and purifying vinyl acetate according to claim 1, characterized in that, The separation and purification method also includes the removal of the mixture adsorbed on the surface of the adsorbent after the adsorption separation is completed.

5. The method for separating and purifying vinyl acetate according to claim 4, characterized in that, The method for removing the mixture adsorbed on the surface of the adsorbent is to air dry the cucurbita[6] porous crystal material at room temperature.

6. The method for separating and purifying vinyl acetate according to claim 1 or 4, characterized in that, The separation and purification method further includes the regeneration of the adsorbent after the adsorption separation is completed.

7. The method for separating and purifying vinyl acetate according to claim 6, characterized in that, The regeneration method of the adsorbent is as follows: under vacuum or inert atmosphere conditions, the cucurbita[6] channel-type crystal material is heated to 40-100°C.

8. The application of cucurbituril[6] porous crystal material as an adsorbent in the separation and purification of vinyl acetate, characterized in that, Using cucurbita[6] porous crystal material as an adsorbent, acetaldehyde impurities in vinyl acetate mixed solution are selectively adsorbed to achieve the separation and purification of vinyl acetate; The structural formula of the cucurbituril[6] channel-type crystal material is as follows:

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