Refining method for alcoholysis waste liquid in PVA (polyvinyl alcohol) production and test device for same
A refining method and technology of alcoholysis waste liquid, which are applied in chemical instruments and methods, preparation of carboxylate, preparation of organic compounds, etc., can solve the problems such as the inability to achieve complete hydrolysis of methyl acetate, and achieve high product purity and technological process. simple effect
Inactive Publication Date: 2015-03-04
FUZHOU UNIV
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Problems solved by technology
Since the hydrolysis reaction is a reversible reaction, methyl acetate cannot be completely hydrolyzed, and the product obtained after hydrolysis is a quaternary product, and there are still separation problems of methyl acetate-methanol and methyl acetate-water azeotrope
Method used
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Embodiment 1
[0035] Methyl acetate refining technology of the present invention is as figure 2 As shown, the raw material is 81.70wt% methyl acetate and 17.8wt% methanol, which are added to tower T-101 from the middle and lower part; the extractant is acetic acid solution, which is added to tower T-101 from the middle and upper part. The column pressure is normal pressure, the operating temperature is room temperature 25°C, the solvent ratio is 2:1, the reflux ratio is 2.5, and the theoretical stages of the column are 31. The product methyl acetate is obtained at the top of the tower. The composition of the tower top and the tower bottom is shown in Table 1, and the conversion rate of methanol is 96.14%. The still liquid enters from the middle and lower part of the solvent recovery tower T-102, methyl acetate, methanol and water distill out from the top of the tower, and the still liquid is acetic acid solution.
[0036]
Embodiment 2
[0038] The difference from Example 1 in Example 2 is that the solvent ratio is 3:1, and the conversion rate is 91.77%. The experimental results are shown in Table 2.
[0039]
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The invention relates to a refining method for an alcoholysis waste liquid in PVA (polyvinyl alcohol) production and a test device for the refining method, wherein the process method is that under the action of a catalyst, an extraction reaction rectification method is adopted, and acetic acid is added as an extractant and a reactant for reacting methanol in the azeotrope of methyl acetate and methanol to generate methyl acetate. The method specifically comprises the following steps of: 1) conveying the measured azeotrope of methyl acetate and methanol from the middle-lower part of an extraction reaction rectification tower, conveying the measured and proportioned extractant, namely, the acetic acid solution, from the upper part of the extraction reaction rectification tower, obtaining the methyl acetate in a concentration of 99.5% on the tower top of the extraction reaction rectification tower, and obtaining the acetic acid solution containing a small amount of methyl acetate, methanol and water on the tower bottom; and 2) conveying the residue from the extraction reaction rectification tower in an extractant recovery tower, rectifying out methyl acetate and methanol on the tower top of the extractant recovery tower and returning the methyl acetate and the methanol into the alcoholysis liquid azeotropic rectification tower of a PVA system, obtaining an acetic acid aqueous solution on the tower bottom of the extractant recovery tower and returning the acetic acid aqueous solution into the acetic acid concentration tower of the PVA system.
Description
technical field [0001] The invention relates to a refining technology of polyvinyl alcohol (PVA) alcoholysis waste liquid, in particular to a method for refining alcoholysis waste liquid in PVA production and a test device thereof, especially a method combining extractive distillation and reactive distillation Methyl acetate purification technology. Background technique [0002] In the production process of polyvinyl alcohol (PVA), a large amount of by-product methyl acetate will be produced when polyvinyl acetate is alcoholyzed to generate polyvinyl alcohol. Usually, for every ton of PVA synthesized, about 1.68 tons of methyl acetate will be obtained at the same time. . The purity of methyl acetate in the alcoholysis waste liquid is not high, and it contains a lot of methanol. The content of methanol is generally 74wt%, methyl acetate is 18wt%, and there are a small amount of other impurities. The value of direct use is not great, and usually needs to be separated Recycle...
Claims
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IPC IPC(8): C07C69/14C07C67/54C07C67/60
Inventor 赵素英郑辉东白姣姣曾燕茹
Owner FUZHOU UNIV