Method for preparing xylene by shape-selective disproportionation of toluene

A technology of p-xylene and toluene, which is applied in the field of toluene shape-selective disproportionation to p-xylene, can solve the problem of replenishing hydrogen consumption and achieve the effect of reducing consumption

Active Publication Date: 2015-01-14
CHINA PETROLEUM & CHEM CORP +1
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  • Abstract
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  • Claims
  • Application Information

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Problems solved by technology

[0007] The technical problem to be solved by the present invention is that in the existing toluene shape-selective disproportionation reaction process, under the process of hydrogen-containing reaction conditions, a large amount of circulating hydrogen after the reaction is discharged out of the reaction system, resulting in a large consumption of supplementary hydrogen.

Method used

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  • Method for preparing xylene by shape-selective disproportionation of toluene

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Experimental program
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Effect test

Embodiment 1

[0026] In this process embodiment, it is assumed that the conversion rate of toluene is 30%, and the supplementary hydrogen contains 92% hydrogen. The following embodiments are the same.

[0027] The reaction aromatics feed containing 99% toluene and the circulating hydrogen containing 90.5% are exchanged through the inlet and outlet materials, and then fed through the heating furnace. The materials enter the reactor containing ZSM-5 molecular sieve catalysts. Then after air cooling, the material is water cooled and the temperature is 25°C, and it enters the gas-liquid separator for separation. The circulating gas phase contains 89% hydrogen, and the circulating hydrogen is not exhausted. The compression cycle is returned to the reaction system, and the liquid phase enters the subsequent liquid phase separation system.

[0028]

Embodiment 2

[0030] The reaction aromatics feed containing 80% toluene and the circulating hydrogen containing 86.0% are exchanged through the inlet and outlet materials, and then fed through the heating furnace. The materials enter the reactor containing the ZSM-11 molecular sieve catalyst. Then the material is air-cooled and then water-cooled at a temperature of 50°C. It enters the gas-liquid separator for separation. The circulating gas phase contains 81.0% hydrogen, and the circulating hydrogen is not exhausted. The compression cycle is returned to the reaction system, and the liquid phase enters the subsequent liquid phase separation system.

[0031]

Embodiment 3

[0033] The reaction aromatics feed containing 70% toluene and the circulating hydrogen containing 88.0% are exchanged through the inlet and outlet materials and then fed into the heating furnace. The materials enter the reactor containing ZSM-5 molecular sieve catalysts. Then after air cooling, the material is water cooled and the temperature is 10°C, and it enters the gas-liquid separator for separation. The circulating gas phase contains 86.0% hydrogen, and the circulating hydrogen is not exhausted. The compression cycle is returned to the reaction system, and the liquid phase enters the subsequent liquid phase separation system.

[0034]

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Abstract

The invention relates to a method for preparing xylene by shape-selective disproportionation of toluene to mainly solve the technical problem that a lot of recycle hydrogen is discharged out of a reaction system after a reaction under the hydrogen-containing reaction condition and supplemental hydrogen is greatly consumed in the prior art. The method for preparing xylene by shape-selective disproportionation of toluene comprises the following steps: reaction materials toluene and recycle hydrogen pass through a feed-in and feed-out exchanger to be heated so as to form a mixed material I; the mixed material I is heated by a heating furnace and enters a reactor, a material II obtained after a reaction enters a feed-in and feed-out heat exchanger and is cooled, and the material II enters a gas-liquid separator to be separated after being cooled; a gas phase in the upper part of the gas-liquid separator enters a gas-phase circulatory system; the recycle gas phase is mixed with supplemental hydrogen, and the mixture is recycled to the reaction system after pressurization; and a liquid phase in the lower part of the gas-liquid separator enters a subsequent liquid-phase separation system. By the technical scheme, the above problem is solved well. The method can be applied in industrial production of a shape-selective disproportionation reaction of toluene.

Description

technical field [0001] The invention relates to a method for preparing p-xylene by shape-selective disproportionation of toluene. Background technique [0002] Paraxylene (PX) is one of the main basic organic raw materials in the petrochemical industry. It has a wide range of uses in many chemical production fields such as chemical fibers, synthetic resins, pesticides, medicines, and plastics. The typical p-xylene production method is from the thermodynamic equilibrium mixed xylene generated by the catalytic reforming process of naphtha and the toluene disproportionation and transalkylation process through multi-stage cryogenic crystallization separation or molecular sieve simulated moving bed adsorption separation (referred to as Adsorption separation) technology to separate p-xylene from the isomer mixture with a boiling point close to it. For the treatment of ortho- and meta-xylene and ethylbenzene, mixed xylene isomerization (isomerization for short) technology is ofte...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C15/08C07C15/04C07C6/12
Inventor 孔德金李为祁晓岚陈秉
Owner CHINA PETROLEUM & CHEM CORP
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