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Method for Simulated Moving Bed Adsorption and Separation of Paraxylene in C8 Aromatics

A technology for simulating moving bed and C8 aromatics, which is applied in the field of isomers and can solve problems such as poor separation effect

Active Publication Date: 2021-08-06
CHINA PETROLEUM & CHEM CORP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Use barium-exchanged faujasite molecular sieves to separate p-xylene from Coctaaromatics, and use p-diethylbenzene as a desorbent. When only the temperature of the raw material and the desorbent are different, the isothermal operation at a suitable temperature has the best separation Performance; when heat exchangers are added between different areas to control the temperature of different areas, a better separation effect can be obtained under a suitable temperature gradient, but only by controlling the temperature of the raw material and desorbent, the separation effect is not good

Method used

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  • Method for Simulated Moving Bed Adsorption and Separation of Paraxylene in C8 Aromatics
  • Method for Simulated Moving Bed Adsorption and Separation of Paraxylene in C8 Aromatics
  • Method for Simulated Moving Bed Adsorption and Separation of Paraxylene in C8 Aromatics

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Experimental program
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preparation example Construction

[0022] The preparation method of the above-mentioned adsorbent is as follows: mixing NaX zeolite with a binder, rolling into balls, and roasting to obtain matrix pellets. Then use barium and / or potassium compound solution to carry out ion exchange, and after exchange, the solid is dried and activated to obtain the adsorbent. The compound containing potassium and barium is preferably nitrate or chloride of potassium or barium. When preparing an adsorbent with BaKX zeolite as an active component, the matrix pellets can be contacted with a barium-containing compound solution for Ba ion exchange, and then contacted with a potassium-containing compound solution for K ion exchange, and then dried and activated. The calcination temperature is preferably 480-560°C, and the drying temperature is preferably 90-130°C.

[0023] The desorbent used in the adsorption and separation process of the method of the present invention is p-diethylbenzene, whose boiling point is higher than that of...

example 1

[0032] Prepare the adsorbent used in liquid phase adsorption separation.

[0033] Mix NaX zeolite with a silica / alumina molar ratio of 2.4 and kaolin at a mass ratio of 92:8, roll into a ball, and bake at 520°C for 6 hours to take spherical particles with a particle size of 0.5 to 1.0 mm, and use barium nitrate solution Carry out ion exchange, the liquid / solid volume ratio of solution and adsorbent is 10, the concentration of barium nitrate solution is 0.3mol / L, and the exchange degree calculated according to the residual sodium content after exchange is 95 mol%. After the exchange, the solid was dried at 100° C. for 3 hours and activated at 220° C. for 2 hours to obtain an adsorbent A, wherein the content of BaX was 93.41% by mass and the content of kaolin was 6.59% by mass.

example 2

[0035] Mix NaX zeolite with a silica / alumina molar ratio of 2.4 and kaolin at a mass ratio of 92:8, roll into a ball, and bake at 520°C for 6 hours to take spherical particles with a particle size of 0.5 to 1.0 mm, and use barium nitrate solution For ion exchange, the liquid / solid volume ratio of the solution to the adsorbent is 10, and the concentration of the barium nitrate solution is 0.3 mol / L. Get the solid after Ba ion exchange and carry out ion exchange with the solution of Potassium Chloride, the concentration of Potassium Chloride is 0.5mol / L, and the liquid / solid volume ratio of solution and adsorbent is 2, calculates by the residual sodium content after exchange The degree of exchange was 95 mol%. After the exchange, the solid was dried at 100°C for 3 hours and activated at 220°C for 2 hours to obtain Adsorbent B, wherein the content of BaKX was 93.1% by mass, the content of kaolin was 6.9% by mass, and the molar ratio of K to Ba in the BaKX zeolite was 0.12.

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Abstract

A method for adsorbing and separating p-xylene from C8 aromatics in a liquid-phase simulated moving bed, comprising feeding the C8 aromatics raw material into the simulated moving bed to absorb the p-xylene therein, obtaining a raffinate, and feeding it into the adsorption bed The desorbent desorbs the adsorbed p-xylene, obtains the extract and discharges it from the simulated moving bed, and the material entering and leaving the simulated moving bed divides the adsorption bed into a desorption area, a purification area, an adsorption area and an isolation area. The active component of the adsorbent is BaX or BaKX zeolite, and the desorbent is p-diethylbenzene. The temperature of the C8 aromatics raw material entering the simulated moving bed adsorption bed is controlled at 100-155°C, and the desorption of the simulated moving bed adsorption bed is carried out. The agent temperature is 170-210°C. The method can improve the separation efficiency of the simulated moving bed separation process of p-xylene in C8 aromatics.

Description

technical field [0001] The invention is a method for separating isomers in raw materials by using simulated moving bed adsorption, in particular, a method for separating p-xylene from C8 aromatics. Background technique [0002] Para-xylene (PX) is an important chemical raw material, mainly used in the production of refined terephthalic acid (PTA) and dimethyl terephthalate (DMT), with a purity of at least 99.5%, preferably greater than 99.7%. [0003] In the prior art, p-xylene is mainly separated from a mixture of C8 aromatic hydrocarbon isomers. Mixed C8 aromatics mainly come from catalytic reforming, steam cracking, toluene disproportionation and transalkylation, and the concentration of p-xylene is generally between 15% and 25%. The boiling points of the isomers of C8 aromatics are close: ethylbenzene 136.2°C, p-xylene 138.4°C, m-xylene 139.1°C, ortho-xylene 144.4°C, among which the highest boiling point of o-xylene can be separated by rectification. With hundreds of t...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07C7/13C07C15/08
CPCC07C7/13C07C15/08
Inventor 王德华杨彦强郁灼王辉国马剑锋王红超李犇
Owner CHINA PETROLEUM & CHEM CORP
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