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Method for preparing terephthalic acid by oxidation refining process

A technology for terephthalic acid and oxidative purification, applied in chemical instruments and methods, preparation of organic compounds, organic chemistry, etc., can solve the problems of large consumption of catalytic combustion, increase of bromide content, increase of investment cost, etc. The effect of reducing catalytic combustion loss and carbon dioxide production, reducing corrosion effect, and reducing total consumption

Inactive Publication Date: 2013-04-03
CHINA PETROLEUM & CHEM CORP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0007] Among the above methods, CN87107051A adopts aqueous solution oxidation method and hydrogenation method for refining treatment, the process flow is long, and many catalyst components are added, which easily pollutes the final product
US4772748A adopts an oxidation method to produce terephthalic acid, the oxidation step is long, and the consumption caused by catalytic combustion is large
CN1512976A adopts the method of one-step oxidation, liquid-solid separation, and further oxidation of solid products. Although the combustion consumption is reduced, the increase of liquid-solid separation devices increases the failure rate of the production process and increases the investment cost.
At the same time, the above-mentioned patent uses a higher concentration of bromine catalyst (usually greater than 600ppm) in the first stage of liquid-phase oxidation of p-xylene, resulting in an increase in the bromide content in the process of equipment corrosion and oxidation
In order to avoid the corrosion effect of the reaction liquid with high bromine concentration on the reactor, pipeline and some units, these parts contacting the reaction liquid are made of expensive titanium materials, thus increasing the cost of investment
And the high bromine concentration in the reactor also increases the content of bromine components in the reaction tail gas, causing pollution to the environment

Method used

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  • Method for preparing terephthalic acid by oxidation refining process
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  • Method for preparing terephthalic acid by oxidation refining process

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0065] 100 grams of p-xylene, 500 grams of acetic acid, 50 grams of water, together with 2.1 grams of cobalt acetate (containing four molecules of crystal water), 2.1 grams of manganese acetate (containing four molecules of crystal water), 0.7 grams of cerium acetate and 0.01 grams of tetrabromoethyl The alkanes were added to a ventilated stirred tank with a volume of 1 liter. Introduce nitrogen protection, start stirring at the same time, raise the temperature of the reaction liquid to 185 ° C, the pressure to 1.2 MPa, and feed pressurized air at a flow rate of 10 L / min (under standard conditions) to start the reaction. The oxygen concentration in the tail gas adopts The magnetic oxygen analyzer is used for real-time detection, and the carbon dioxide in the tail gas is detected by an infrared online analyzer. During the reaction process, the temperature in the kettle was maintained at 185±1° C. by controlling the evaporation and condensation of steam and the temperature of th...

Embodiment 2

[0078] Essentially the same as Example 1, but during the first oxidation step, 0.03 gram of tetrabromoethane was added. The result of the first step oxidation reaction is that the p-xylene content in the liquid phase is 0.0%, and the content of p-toluic acid and p-carboxybenzaldehyde is 16.5% and 0.80% respectively, indicating that when the trace bromine concentration is close to 40 ppm, the oxidation reaction is accelerated. The conversion rate of p-xylene in the reaction product reached 100%, and the content ratio of p-toluic acid and p-carboxybenzaldehyde in the oxidation product was more reasonable, close to 20.6:1. From the color of the oxidation reaction slurry, the color of the oxidized solid product is white, and the liquid is light yellow.

[0079]

Embodiment 3

[0081] Essentially the same as Example 1, but during the first oxidation step, 0.035 g of tetrabromoethane was added. The result of the first step oxidation reaction is that the p-xylene content in the liquid phase is 0.0%, and the content of p-toluic acid and p-carboxybenzaldehyde is 12.5% ​​and 0.660% respectively, indicating that when the trace bromine concentration is close to 50 ppm, the oxidation reaction is accelerated. The conversion rate of p-xylene in the reaction product reached 100%, and the content ratio of p-toluic acid and p-carboxybenzaldehyde in the oxidation product was more reasonable, close to 18.9:1. From the color of the oxidation reaction slurry, the color of the oxidized solid product is white, and the liquid is light yellow.

[0082] The above experimental results are summarized in Table 1. The results of the comparative experiment in the first oxidation reaction zone show that in the experiment adding Ce, the solid phase product TPA is white, and the...

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Abstract

The invention discloses a method for preparing terephthalic acid by an oxidation refining process. Terephthalic acid is prepared by implementing a liquid-phase catalytic oxidation reaction on p-xylene and oxygen in the presence of a catalyst, wherein the oxidation reaction is performed in a plurality of oxidation reaction zones by various steps; in a first oxidation reaction zone, Co-Mn-Ce is taken as a main body, and a catalytic system in which trace amount of bromide is added is applied to the liquid-phase catalytic oxidation; after adding a bromine catalyst to the product, the liquid-phase catalytic oxidation is further implemented in a second oxidation reaction zone; an oxidation product in the second oxidation reaction zone is directly, or after a liquid-solid separation, processed by a liquid-phase catalytic oxidation in a third oxidation reaction zone to purify, and the purified product is extracted to produce the terephthalic acid product. The method disclosed by the invention adopts different catalytic systems through a selectivity, in order to improve the selectivity of the oxidation process, reduce the catalytic combustion loss, and lower contents of p-toluic acid and p-carboxyl benzaldehyde; and meanwhile, the total amount of bromine in the oxidation process is reduced, so that the corrosion of the catalyst on the equipment is reduced.

Description

technical field [0001] The present invention relates to a method for preparing terephthalic acid, in particular to a process for preparing terephthalic acid by liquid-phase air oxidation of p-xylene, in order to reduce the content of intermediate impurities, the terephthalic acid is prepared by oxidation refining method. Background technique [0002] As a petrochemical raw material and intermediate, terephthalic acid is the main raw material for the production of polyester bottle flakes and chemical fibers, and is widely used in the production of chemical products. At present, terephthalic acid mainly adopts the production process of air oxidation of p-xylene, that is, firstly, crude terephthalic acid is generated through liquid-phase air catalytic oxidation of p-xylene under the action of Co / Mn / Br catalyst. This method can Realize the high conversion rate and high selective oxidation of p-xylene, and obtain the intermediate product p-carboxybenzaldehyde (4-CBA) with a cont...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C63/26C07C51/265C07C51/487
CPCY02P20/52
Inventor 刘建新刘波孙伟振陈韶辉赵玲柏基业江一君肖翔邢跃军高洪伟王玉春
Owner CHINA PETROLEUM & CHEM CORP
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