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Method for separating p-xylene crystal

A technology for the separation of p-xylene and crystallization, which is applied in crystallization purification/separation, organic chemistry, etc., can solve the problems of complex operation and high investment in xylene, and achieve the effect of cheap price, low investment and good technical effect

Active 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

[0006] The technical problem to be solved by the present invention is to provide a new crystallization and separation method for p-xylene due to the problems of high investment and complicated operation for adsorption, separation and purification of p-xylene in the prior art

Method used

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  • Method for separating p-xylene crystal

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Experimental program
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Effect test

Embodiment 1

[0015] The mixed xylene raw material is sent to the scraping wall crystallizer, and the crystallization temperature is -10°C to form a slurry. The slurry is sent to a simulated moving bed with 6 beds, and the flow is switched through a rotary valve to realize the simulated moving bed. Different functions, one of which is a filter bed, three are washing beds, one is a crystal melting bed, and one is a product output bed. The slurry was filtered, washed and crystals were purified in a simulated moving bed, and the washing liquid / crystal weight ratio was 0.2 to obtain pure p-xylene. After the test runs stably, the composition of each stream is shown in Table 1.

[0016] The composition (% by weight) of each stream among the table 1 embodiment 1

[0017] components raw material mother liquor Rinse pure p-xylene Ethylbenzene 5.0 11.2 5.8 0.0 m-xylene 5.0 11.4 6.2 0.1 O-xylene 10.0 22.6 12.6 0.1 p-xylene 80.0 54.8 75.4 99.8 ...

Embodiment 2

[0019] The mixed xylene raw material is sent to the stirring crystallizer, and the crystallization temperature is -80°C to form a slurry. The slurry is sent to a simulated moving bed with 10 beds, and the flow is switched through a rotary valve to realize the difference of the simulated moving bed Function, of which 1 bed is filter bed, 5 are washing beds, 3 are crystal melting beds, and 2 are product output beds. The slurry was filtered, washed and crystals were purified in a simulated moving bed, and the washing liquid / crystal weight ratio was 0.5 to obtain pure p-xylene. After the test runs stably, the composition of each stream is shown in Table 2.

[0020] The composition (% by weight) of each stream in the embodiment 2 of table 2

[0021] components raw material mother liquor Rinse pure p-xylene Ethylbenzene 15.0 33.5 14.4 0.1 m-xylene 10.0 19.7 8.7 0.0 O-xylene 15.0 34.1 13.4 0.1 p-xylene 60.0 12.7 63.5 99.8

Embodiment 3

[0023] The mixed xylene raw material is sent to the scraping wall crystallizer, and the crystallization temperature is 5°C to form a slurry. The slurry is sent to a simulated moving bed with 8 beds, and the flow is switched through a rotary valve to realize the difference of the simulated moving bed Function, of which 1 bed is filter bed, 3 are washing beds, 2 are crystal melting beds, and 2 are product output beds. The slurry was filtered, washed and crystals were purified in a simulated moving bed, and the washing liquid / crystal weight ratio was 0.05 to obtain pure p-xylene. After the test runs stably, the composition of each stream is shown in Table 3.

[0024] The composition (% by weight) of each stream among the table 3 embodiment 3

[0025] components raw material mother liquor Rinse pure p-xylene Ethylbenzene 2.0 7.2 3.7 0.1 m-xylene 1.0 3.5 1.8 0.0 O-xylene 2.0 7.6 3.3 0.1 p-xylene 95.0 81.7 91.2 99.8

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Abstract

Provided is a process for crystallization separating p-xylene, comprising: a) feeding a mixed xylenes stream comprising greater than or equal to 60% by weight, of p-xylene, such as 60% to 98% by weight of p-xylene, to a crystallization unit to perform cooling crystallization, to obtain a slurry comprising p-xylene crystals; and b) feeding the slurry to a filtration and purification unit, to obtain a mother liquor, washings, and p-xylene, wherein the filtration and purification unit uses a simulated moving bed or a combination of multiple moving beds.

Description

technical field [0001] The invention relates to a method for crystallization and separation of p-xylene. Background technique [0002] P-xylene is one of the main basic organic raw materials in the petrochemical industry. It is widely used in many chemical production fields such as chemical fibers, synthetic resins, pesticides, medicines, and plastics. The typical production method of p-xylene is from the thermodynamically balanced xylene containing ethylbenzene, that is, C8 aromatics generated by catalytic reforming of naphtha, through multi-stage cryogenic crystallization separation or molecular sieve simulated moving bed adsorption separation (adsorption separation for short) Technology to separate p-xylene from a mixture of isomers with similar boiling points. [0003] C 8 The boiling points of the components of aromatic hydrocarbons are close: ethylbenzene 136.2°C, p-xylene 138.4°C, m-xylene 139.1°C, ortho-xylene 144.4°C. Among them, o-xylene with the highest boiling ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07C15/08C07C7/14
CPCC07C7/14C07C15/08
Inventor 钟禄平肖剑卢咏琰郭艳姿孔德金
Owner CHINA PETROLEUM & CHEM CORP
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