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Process for producing high purity meta-xylene, comprising simulated moving bed adsorption and crystallization

A technology for simulating moving bed and m-xylene, applied in the field of copolymers with terephthalic acid

Inactive Publication Date: 2008-10-29
INST FR DU PETROLE
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0016] None of the above patents proposes the production of m-xylene by coupling the adsorption and crystallization steps

Method used

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  • Process for producing high purity meta-xylene, comprising simulated moving bed adsorption and crystallization

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0077] Embodiment 1 (according to prior art)

[0078] The prior art process includes simulated moving bed separation equipment capable of producing meta-xylene with a purity of 99.1%.

[0079] This example illustrates the production of meta-xylene with a purity of 99.1%. m-xylene was separated by countercurrent simulated moving bed adsorption. The ortho-xylene-rich starting material has the following weight composition:

[0080] PX: 3.57% p-xylene

[0081] MX: 55.84% m-xylene

[0082] OX: 28.36% o-xylene

[0083] EB: 11.79% ethylbenzene

[0084] TOL: 0.44% toluene.

[0085] The pilot plant used consisted of 24 towers 1.1 m long and 0.021 m in diameter. Each tower is equipped with 240.6g of sodium-exchanged Y zeolite, and the moisture content represented by the loss on ignition at 900° C. is lower than 0.1%.

[0086] The operating temperature is 160°C and the suction pressure of the circulation pump is maintained at 10 bar.

[0087] All of these streams are continuou...

Embodiment 2

[0101] Embodiment 2 (the present invention)

[0102] This example illustrates the plant of the invention comprising 15 adsorbent bed adsorption plants coupled to the crystallization section and capable of producing m-xylene with a purity of 99.7%.

[0103] The pilot plant used consists of 15 towers with a length of 1.1 m and a diameter of 0.021 m. Each tower is equipped with 240.6 g of sodium-exchanged Y zeolite, and the moisture content expressed by the loss on ignition at 900° C. is less than 0.1%. The operating temperature is 160°C and the suction pressure of the circulation pump is maintained at 10 bar.

[0104] All of these streams are continuously injected or withdrawn under flow control, with the exception of raffinate, which is continuously withdrawn under pressure control, said injection and withdrawal rates being expressed under the conditions of the process.

[0105] The total number of beds is 15, which are allocated in the following manner.

[0106] - 3 beds b...

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Abstract

The invention concerns a process for producing high purity meta-xylene, comprising a step for separation by simulated moving bed adsorption starting from an aromatic C8 feed delivering a fraction which is rich in meta-xylene and a fraction which is depleted in meta-xylene, and a step for crystallization of the meta-xylene rich fraction. The purity of the meta-xylene produced is at least 99.5%.

Description

technical field [0001] The present invention relates to a novel process for the separation of m-xylene from a mixture of C8 aromatic isomers with improved yield and low operating costs to produce very high purity m-xylene which can be used in the synthesis of isophthalic acid, It is used in particular as a copolymer with terephthalic acid by itself. Background technique [0002] The prior art describes various production methods for the production of meta-xylene combined with the co-production of one or more products such as para-xylene, ortho-xylene and ethylbenzene. [0003] Patent US 4 326 092 describes an example of m-xylene with a purity of at least 99.5% obtained by adsorption separation in a simulated moving bed. However, this reference only teaches the use of orthoxylene-depleted process streams. This reference states that the A / F ratio (ratio of selective pore volume flow to feed volume flow) for a treated feed having the following composition is 1.5: 6.0% paraffi...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C15/08C07C7/14C07C7/12C07C7/04
CPCC07C7/13C07C15/08C07C7/14
Inventor G·霍蒂尔P·勒弗莱夫L·沃尔夫
Owner INST FR DU PETROLE
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