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Method for simulated moving bed adsorption separation of p-xylene in C8 aromatic hydrocarbon

A technology for simulating moving bed and carbon octane aromatics, which is applied in the field of isomers, can solve the problems of poor separation effect and achieve the effect of improving the efficiency of adsorption and separation

Active Publication Date: 2018-05-11
CHINA PETROLEUM & CHEM CORP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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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 separation of p-xylene in C8 aromatic hydrocarbon
  • Method for simulated moving bed adsorption separation of p-xylene in C8 aromatic hydrocarbon
  • Method for simulated moving bed adsorption separation of p-xylene in C8 aromatic hydrocarbon

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preparation example Construction

[0022] The preparation method of the above adsorbent is as follows: the NaX zeolite is mixed with the binder, and then rolled and calcined to obtain matrix pellets. The ion exchange is carried out with the compound solution containing barium and / or potassium, and the adsorbent is obtained after the exchanged solid is dried and activated. The potassium and barium-containing compounds are preferably potassium and barium nitrates or chlorides. When preparing the adsorbent with BaKX zeolite as the active component, the matrix pellets can be contacted with the barium-containing compound solution for Ba ion exchange, and then contacted with the 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 invention is p-diethylbenzene, the boiling point of which is...

example 1

[0032] Preparation of adsorbents for liquid phase adsorption separation.

[0033] The NaX zeolite with a silica / alumina molar ratio of 2.4 was mixed with kaolin in a mass ratio of 92:8, rolled into a ball, and calcined at 520°C for 6 hours. 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 95mol%. After the exchange, the solid was dried at 100° C. for 3 hours, and activated at 220° C. for 2 hours to obtain adsorbent A, in which the BaX content was 93.41 mass % and the kaolin content was 6.59 mass %.

example 2

[0035] The NaX zeolite with a silica / alumina molar ratio of 2.4 was mixed with kaolin in a mass ratio of 92:8, rolled into a ball, and calcined at 520°C for 6 hours. 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 the solution and the adsorbent is 2, calculated according to the residual sodium content after the 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 BaKX content was 93.1 mass%, the kaolin content was 6.9 mass%, and the molar ratio of K to Ba in BaKX zeolite was 0.12.

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Abstract

The invention discloses a method for liquid phase simulated moving bed adsorption separation of p-xylene in C8 aromatic hydrocarbon. The method includes: introducing a C8 aromatic hydrocarbon raw material into a simulated moving bed to adsorb bed p-xylene therein to obtain raffinate, introducing a desorption agent into adsorption bed layers to desorb the adsorbed p-xylene, discharging the obtainedextracted liquid out of the simulated moving bed, separating the adsorption bed layers into a desorption area, a purification area, an adsorption area and an isolation area by the materials going inand out of the simulated moving bed, wherein the adsorbent active ingredient is BaX or BaKX zeolite, and the desorption agent is p-diethylbenzene, controlling the temperature of the C8 aromatic hydrocarbon raw material entering the adsorption bed layers of the simulated moving bed at 100-155DEG C, and the temperature of the desorption agent introduced into the adsorption bed layers of the simulated moving bed at 170-210DEG C. The method can improve the separation efficiency of the process for simulated moving bed separation of p-xylene in C8 aromatic hydrocarbon.

Description

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

Claims

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Application Information

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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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