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Process for primary refining coarse p-phthalic acid by solvent washing process

A technology of crude terephthalic acid and purified terephthalic acid, which is applied in the separation/purification of carboxylic acid compounds, can solve the problems of high catalyst index and influence on hydrotreating, and achieves reduction in consumption, reduction in separation cost, The effect of reducing production

Inactive Publication Date: 2004-07-07
中国石化集团天津石油化工公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Although this method reduces the amount of washing water and successfully saves the drying process, the residual catalyst index in the CTA slurry fed as the PTA process is too high, which affects the hydrofining process.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0027] Take the slurry obtained from the PX oxidation reactor product after flash evaporation to remove part of the acetic acid, filter to obtain 120 grams of filter cake, and control the moisture content of the filter cake to 18-22%. Beat and wash with 60 grams of mixed solvent, the ratio of mixed solvent is: 40 grams of PX, 20 grams of water. The washing conditions are: normal pressure, 70-90°C. After washing, use a Buchner funnel to filter under a vacuum of 200-400mmHg. Then replace and wash the obtained filter cake with 120 grams of water, that is, pour water on the crude terephthalic acid crystals, and the liquid level of the water should be higher than the surface of the crude terephthalic acid crystals. The washing conditions are: normal pressure, 70-90°C. Filter while pouring. The obtained filter cake can be used as the feed for the hydrogenation refining process after being mixed with water in an appropriate proportion. The results are shown in Table 1.

Embodiment 2～7

[0029] In Example 1, the amount of mixed solvent and water was changed, and the washing method was changed. The results are shown in Table 1.

Embodiment 8

[0031] In Example 1, the composition of the mixed solvent was changed to 40 grams of PX, 10 grams of water, and 10 grams of acetic acid, and washed in the above-mentioned manner C. The results are shown in Table 2.

[0032] Example No.

[0033] Note * : The amount of mixed solvent and the amount of washing water refer to the weight ratio of solvent or washing water to crude TA.

[0034] Washing method: A-Firstly, beating and washing with a mixed solvent, then filtering and washing with water.

[0035] B-First replace and wash with a mixed solvent, then filter and then replace and wash with water.

[0036] C-Beat and wash with a mixed solvent first, filter and then wash with water, and then replace and wash with water.

[0037] ** : First beating and washing with 0.4 times of water, and then replacing and washing with 0.8 times of water.

[0038] Ash refers to the ash content of the filter cake after drying.

[0039] mix

[0...

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PUM

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Abstract

A process for primarily refining coarse terephthalic acid (CTA) by solvent washing method includes such steps as using the mixture of p-xylene (PX), water and acetic acid to wash the acetic acid contained terephthalic acid slurry generated by the oxidizing reactor for preparing terephthalic acid by oxidizing PX, solid-liquid separating to obtain CTA crystal containing acetic acid and catalyst, washing with water, mixing with water, and hydrorefining.

Description

technical field [0001] The invention belongs to a method for refining terephthalic acid and relates to a method for preliminarily refining crude terephthalic acid by solvent washing. Background technique [0002] Terephthalic acid is usually produced by reacting p-xylene (PX) with molecular oxygen in acetic acid in the presence of a catalyst containing cobalt, manganese and bromine, etc. The crude terephthalic acid separated from the acetic acid slurry of the reaction product terephthalic acid is hydrotreated to remove p-carboxybenzaldehyde (4-CBA) to obtain purified terephthalic acid. Crude terephthalic acid (PTA) before hydrofinishing must be fully dried to remove residual acetic acid. In the drying process in this method, the cost of drying equipment is high, and there are many auxiliary equipments, and the operation is complicated. [0003] Several solutions have been proposed around how to omit the drying procedure. Mainly the acetic acid in the terephthalic acid slu...

Claims

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Application Information

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IPC IPC(8): C07C51/42C07C63/26
Inventor 符强齐彦伟崔凤霞徐敬宇
Owner 中国石化集团天津石油化工公司
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