Preparing method for acrylic acid

A technology of acrylic acid and crude acrylic acid, which is applied in the preparation of carboxylate, the preparation of organic compounds, chemical instruments and methods, etc., can solve the problems of lowering the efficiency of raw materials, lowering the quality of acrylic acid, forming by-products, etc. Final yield, effect of preventing polymerization

Inactive Publication Date: 2004-02-04
NIPPON SHOKUBAI CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, since pressure and concentration change simultaneously with temperature, it is difficult to control these factors
[0009] In the purification process of acrylic acid, not only the acrylic acid polymer but also the by-products produced by the catalytic gas phase oxidation reaction are attached to equipment such as distillation towers, which inevitably leads to adverse results such as equipment clogging and may impair the long-term stability of acrylic acid Production
[0010] In the high boiler-containing solution resulting from the separation of high boilers, in addition to the dimer of acrylic acid, so-called Michael adducts of acrylic acid are present, leading to a reduction in the efficiency of the raw materials used in the process for the production of acrylic acid
When Michael adducts accumulate in the production process, it will seriously hinder the purification process and production process, and will inevitably cause temperature rise and formation of by-products, which may reduce product quality to a certain extent
When the above compounds are recovered as acrylic acid, this recovery may result in lower quality of acrylic acid

Method used

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  • Preparing method for acrylic acid
  • Preparing method for acrylic acid

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0096] according to figure 1 Illustrated process flow for the production of acrylic acid. First, in the presence of an oxidation catalyst, the catalytic gas phase oxidation of propylene and molecular oxygen was carried out at 388 Nm 3 / Min, a mixed gas containing 7.1% by volume of acrylic acid, 0.3% by volume of acetic acid and 14.7% by volume of water was obtained.

[0097] This gas was introduced into an absorption column (cascade miniring 3P 10m) and a bottom liquid was obtained at a rate of 8050 kg / h. The absorption tower was operated at 62°C and the pressure at the top of the tower was maintained at 1100 hPa absolute. At a rate of 2720 kg / h, the water obtained by mixing the hydroquinone polymerization inhibitor, the separated water produced in the azeotropic dehydration tower, and the water containing 1.5% by weight of acrylic acid and 5.4% by weight of acetic acid produced by the vacuum generator in the distillation tower Wastewater is supplied to the top of the colum...

Embodiment 2

[0103] At the section of the azeotropic dehydration tower that provides the aqueous solution, hydroquinone dissolved in water is provided to the azeotropic dehydration tower together with the aqueous acrylic acid solution as part of the polymerization inhibitor, and is operated according to the method of Example 1. After about a week of continuous operation, the pressure loss in the azeotropic dehydration column showed signs of increasing. After about 2 months of continuous operation, the whole plant was opened and examined and it was found that polymer was deposited on the sieve tray above the section of the column supplying the aqueous acrylic acid solution.

Embodiment 3

[0105] Instead of using the overhead liquid of the maleic acid separation tower, hydroquinone was directly provided to the azeotropic dehydration tower as part of the polymerization inhibitor, and operated according to the method of Example 1. From the first day of operation, the pressure loss in the azeotropic dehydration column showed signs of increasing. After about 1 month of continuous operation, the whole set of equipment was opened and internal inspection was carried out, and polymerization inhibitor deposition occurred near the column section where the polymerization inhibitor was introduced, and the holes in the sieve plate were blocked.

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Abstract

A method for the production of acrylic acid comprises (i) a step for introducing a polymerization inhibitor to a stage other than a stage for supplying a raw material and a stage for supplying a reflux of said distilling column or (ii) a step for supplying the acrylic acid recovered by thermally decomposing said oligomer to said stage for dehydration. Thus, the present invention enjoys effective utilization of acrylic acid and exalts the efficiency of production.

Description

technical field [0001] The invention relates to a method for preparing acrylic acid, which comprises the following steps: absorbing acrylic acid-containing gas obtained by catalytic gas-phase oxidation with water, removing low-boiling substances and high-boiling substances, and making the high-boiling substance-containing gas obtained in the removal step The acrylic acid oligomer contained in the solution is thermally decomposed, the method can more effectively prevent the polymerization reaction and the yield can be improved. Background technique [0002] Acrylic acid is used in coatings, textile processing, leather products and building materials, and as a copolymer raw material for the production of acrylic fibers and as an emulsion for the production of adhesives and glues. The demand for acrylic acid is increasing day by day. In order to achieve mass production of acrylic acid using inexpensive raw materials, acrylic acid is generally produced by,...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C51/44C07C51/25C07C51/347C07C51/50C07C57/05C07C57/07
CPCC07C51/252C07C51/347C07C57/04C07C51/44
Inventor 西村武松本行弘真田健次平尾晴纪
Owner NIPPON SHOKUBAI CO LTD
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