Process for producing carboxylic acid

A carboxylic acid and preparatory process technology, applied in the field of carboxylic acid preparation, can solve the problems of increased heat removal load on the cooling surface, reduced cooling surface area, and difficulty in high-speed operation of the scraping device, and achieves high productivity and excellent cleaning performance. Effect

Active Publication Date: 2009-04-15
MITSUBISHI CHEM CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0009] However, the method disclosed in Patent Document 5 cannot sufficiently suppress fouling
In addition, there is also a method of strengthening scraping with the help of a scraping device to reduce solid scaling, but if the scraping is strengthened, the crystals in the tank will be crushed, hindering crystal growth, and coarse crystal particles cannot be obtained
[0010] In addition, in the case of industrial mass production using such a crystallization tank, the crystallization tank needs to have a large internal volume. The area of ​​the cooling surface is relatively smaller, so the heat removal load per unit area of ​​the cooling surface increases, and it cannot operate effectively, and in the crystallization tank with a large internal volume, it is difficult for the scraping device to operate at high speed, etc. , it is actually difficult to deal with industrial production by only expanding the internal volume of the crystallization tank

Method used

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  • Process for producing carboxylic acid
  • Process for producing carboxylic acid
  • Process for producing carboxylic acid

Examples

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preparation example Construction

[0036] The method for producing carboxylic acid of the present invention has a preparatory step before the crystallization step in which carboxylic acid crystals are precipitated from a carboxylic acid-containing liquid in a crystallization tank. Cool to below the crystallization onset temperature.

[0037] The carboxylic acid-containing liquid is not limited as long as it contains at least carboxylic acid and crystallizes carboxylic acid by lowering the temperature. It may be liquid carboxylic acid itself or a liquid in which carboxylic acid is dissolved in a solvent. Specifically, a liquid in which carboxylic acid is dissolved in a solvent to be purified, a liquid containing carboxylic acid (mother liquor) obtained in a carboxylic acid production process, a mother liquor after separating a part of carboxylic acid crystals, melting of carboxylic acid crystals, etc. Liquid, etc., can also be any processed liquid.

[0038] The type of carboxylic acid is not particularly limite...

Embodiment 1

[0080] Using the apparatus shown in FIG. 1, the crystallization step and the preliminary step were performed.

[0081] In the cooler 11, "Tarosamu (trade name, manufactured by N.V. Machinefabriek Terlet Co.)" was used as a double cylindrical scraped surface heat exchanger. This heat exchanger has two sets of scraping parts 20 and 22 each having a scraper (10 mm thick, made of PTFE) 21 as an outer cylinder side scraper device 18 and an inner cylinder side scraper device 19 .

[0082] On the side of the rear stage of the cooler 11, a first crystallization tank 12 and a second crystallization tank 13 each having scraper blades are arranged in series. The volume of the cooler 11 is 0.16% of the total volume of the first crystallization tank 12 and the second crystallization tank 13 .

[0083] First, in the crystallization tanks 12 and 13, add a carboxylic acid-containing liquid (by mixing 4 mass % methanol in methacrylic acid, adjust to a freezing point (crystallization start tem...

Embodiment 2

[0090] The device was operated in the same manner as in Example 1, except that the scraper 21 included in the scraper device 19 on the inner cylinder side and the scraper device 18 on the outer cylinder side was changed to a scraper made of phenolic resin (bakelite) having a thickness of 3.5 mm.

[0091] As a result, a slurry-like carboxylic acid-containing liquid having a cooler outlet temperature of 8.0° C. and containing 8.9% by mass of methacrylic acid crystal particles having a particle diameter of about 80 μm was continuously discharged from the cooler 11 . When this operation was continued, the operation status was also stable after 100 hours, and a slurry-like carboxylic acid-containing liquid containing 37% by mass of methacrylic acid crystal particles with a particle diameter of about 225 μm was obtained from the outlet of the second crystallization tank 13 .

[0092] In addition, at this time, the heat removal load of the first crystallization tank 12 is 6.0MJ / hr / m ...

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Abstract

Before a crystallization step in which a carboxylic acid is crystallized from a carboxylic-acid-containing liquid in crystallization tanks (12) and (13) each having a cooling surface, a preliminary step is conducted in which at least part of the carboxylic-acid-containing liquid is fed to a cooling device (11) equipped with cooling surfaces (15) and (16) and scraping means (18) and (19) for scraping the cooling surfaces and is cooled from a temperature exceeding the crystallization initiation temperature to a temperature not higher than the crystallization initiation temperature. This process is preferable especially when the carboxylic acid is acrylic acid and / or methacrylic acid.

Description

technical field [0001] The present invention relates to a method for producing a carboxylic acid, comprising a crystallization step for depositing carboxylic acid crystals. [0002] This application claims priority based on Japanese Patent Application No. 2006-026766 filed with Japan Patent Office on February 3, 2006, the contents of which are incorporated herein by reference. Background technique [0003] When industrially producing carboxylic acids such as (meth)acrylic acid, a purification process for removing impurities, solvents, and the like generated during the production process is indispensable. As such a refining process, extraction, distillation, crystallization, etc. are commonly used. When the target substance to be removed is a substance with a high boiling point or a high melting point or a highly polymerizable substance, it is often used to purify to a high temperature in a low temperature range. Crystallization method for purity. The most commonly used cry...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C51/43B01D9/02C07C57/04
CPCC07C51/43B01D9/0013B01D9/005C07C57/04B01D9/02
Inventor 田中茂穗安藤佳正杉山美荣治佐藤晴基
Owner MITSUBISHI CHEM CORP
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