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Co-production method for dimethyl benzene, meta dimethyl benzene and/or ortho dimethyl benzene

A technology of o-xylene and m-xylene, applied in chemical instruments and methods, distillation purification/separation, adsorption purification/separation, etc., can solve problems such as increasing flow

Inactive Publication Date: 2003-04-09
INST FR DU PETROLE
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In patent WO99 / 64381, ethylbenzene is sent directly to the crystallization unit, which unhelpfully increases the incoming flow rate

Method used

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  • Co-production method for dimethyl benzene, meta dimethyl benzene and/or ortho dimethyl benzene
  • Co-production method for dimethyl benzene, meta dimethyl benzene and/or ortho dimethyl benzene

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0066] Using a material containing a mixture of xylene and ethylbenzene, which has previously removed hydrocarbons containing 9-10 carbon atoms, a countercurrent simulated moving bed is used to produce p-xylene, and the material has the following weight composition:

[0067] EB: Ethylbenzene 5.6%

[0068] PX: Paraxylene 226%

[0069] MX: m-xylene 49.9%

[0070] OX: o-xylene 21.9%.

[0071] The pilot plant used in this example consisted of 24 beds 1.1 meters long and 0.021 meters in diameter. Each column was loaded with 344 grams of barium-exchanged X zeolite with a moisture content of 5.5% expressed as loss on ignition at 900°C. The operating temperature is 175°C, the suction pressure of the circulating pump is maintained at 10 bar, all streams are continuously injected or discharged under flow control, except that the intermediate raffinate is continuously discharged under pressure control, and the flow rates of injection and discharge are all at Expressed under ambient p...

Embodiment 2

[0091] Repeat the operation of Example 1, adding an o-xylene distillation tower before the crystallization section, so as to improve the crystallization yield.

[0092] As before, 1.2 liters / hour of raffinate R2 is distilled to obtain a fluid flow rate of 0.13 liters / hour, and its weight composition is as follows:

[0093] EB: Ethylbenzene 0.1%

[0094] PX: p-xylene 1.7%

[0095] MX: m-xylene 73.9%

[0096] OX: o-xylene 24.2%.

[0097] The m-xylene yield was 6%. The desorbent-free raffinate 2 is then sent to an o-xylene distillation column. Discharge fluid flow 0.05 liters / hour at the bottom of the tower, and its weight composition is as follows:

[0098] PX: p-xylene 1.2%

[0099] MX: m-xylene 49.4%

[0100] OX: o-xylene 49.4%.

[0101] The o-xylene yield in the bottoms was 79%.

[0102] At the top of the column, the fluid withdrawn at 0.08 l / h had the following weight composition:

[0103] EB: Ethylbenzene 0.2%

[0104] PX: p-xylene 2.1%

[0105] MX: m-xylene 89....

Embodiment 3

[0110] Adopt the same operating conditions as in Example 2, but change the flow ratio of raffinate (R2) and intermediate raffinate (R1): R2 / R1. The flow is as follows:

[0111] Material: 3.24 liters / hour

[0112] Solvent: 5.52 L / h desorbent (99.06% p-diethylbenzene and 0.94% other C 10 Aromatics)

[0113] Extraction: 3.27 liters / hour

[0114] Intermediate raffinate (R1): 3.45 liters / hour

[0115] Raffinate (R2): 2.04 liters / hour

[0116] Circulation flow (in segment 1): 16.4 l / h

[0117] The R2 / R1 ratio is 0.59.

[0118] The switching time (period) of the valve is 70.8 seconds.

[0119] After distillation of p-diethylbenzene, the resulting extract was discharged continuously to a stream of 0.71 liters / hour and a purity of 99.7% p-xylene.

[0120] 2.04 liters / hour raffinate R Distillation, obtain fluid flow rate 0.39 liters / hour, its weight composition is as follows:

[0121] EB: Ethylbenzene 0.07%

[0122] PX: p-xylene 0.98%

[0123] MX: m-xylene 69.8%

[0124] OX:...

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Abstract

A process for co-production of paraxylene, metaxylene and / or orthoxylene from a hydrocarbon feedstock (1) that comprises [1] a separation stage of the feedstock in a simulated moving bed in a chromatographic column (9) that contains a number of beds of an adsorbent, interconnected in a loop, is described, whereby said column comprises an injection (3) of the feedstock, a draw-off (10) of an extract that consists of paraxylene and desorbent, an intermediate fraction (11) (extract or raffinate) that contains ethylbenzene, and a raffinate (12) that contains a mixture of metaxylene and orthoxylene that is virtually free of ethylbenzene and paraxylene and [2] a crystallization stage (27) of the metaxylene and / or orthoxylene fraction. Upstream from the adsorption zone and / or upstream from the crystallization zone, it is possible to distill the entering mixture to produce an orthoxylene-enriched fraction at the bottom and a metaxylene-enriched fraction at the top.

Description

technical field [0001] The invention relates to a co-production method of p-xylene, m-xylene and / or o-xylene, which comprises a combination of a simulated moving bed adsorption unit and a crystallization zone. Background technique [0002] The production of high purity p-xylene by adsorptive separation is well known in the art. This market is widely developed, and its outlet is the production of terephthalic acid, phthalic anhydride and polyethylene terephthalate. The technical background for the production of very high purity p-xylene is described in the applicant's EP-A-531 191 patent. [0003] Conversely, the market for m-xylene is still limited and its use is isophthalic acid. However, the separation of m-xylene and its purity to market specifications (>99%) have been the subject of various processes. Therefore, there have been disclosed in the prior art a number of purification routes for obtaining m-xylene from C8 aromatic hydrocarbon feedstock. In patents US 2 ...

Claims

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Application Information

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IPC IPC(8): C07C7/00C07C7/13C07C15/08
CPCC07C7/005C07C7/13C07C15/08C07C7/04C07C7/12C07C7/14
Inventor P·勒弗莱维L·沃尔夫G·霍蒂尔A·梅蒂维尔
Owner INST FR DU PETROLE
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