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Method for preparing p-cymene from dipentene

A technology for cymene and dipentene, applied in chemical instruments and methods, hydrocarbons, hydrocarbons, etc., can solve the problems of complex process and low cymene content

Active Publication Date: 2020-10-27
CENTRAL SOUTH UNIVERSITY OF FORESTRY AND TECHNOLOGY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0007] In patent CN102691063A, dipentene is passed into multiple fixed-bed reactors, and different temperatures are controlled on different fixed-bed reactors to form a gradually increasing temperature gradient. The process is complicated, and the content of cymene obtained is lower, only 62-82%

Method used

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Embodiment 1

[0038] A method for preparing p-cymene by dipentene, comprising the following steps:

[0039] S1, mix powdery palladium carbon catalyst (mass content of palladium 5-7wt%) and stainless steel θ ring filler with a mass ratio of 1:1, naturally pack in a fixed-bed reactor whose body is a temperature-resistant glass tube, and assemble A good gas phase reaction device; nitrogen gas is introduced at a low speed to exhaust the air in the device and maintain continuous access;

[0040] S2. Heating to bring the temperature inside the vaporizer to 200°C. The outer surface of the fixed-bed reactor is wound with an electric heating belt to heat the inside of the fixed-bed reactor to 180°C. Add industrial dipentene dropwise at a rate of 0.05mL / s. into the vaporizing bottle, and when steam reaches the top of the fixed-bed reactor, turn on the vacuum pump and maintain a vacuum degree of 0.09MPa inside the device, collect the liquid product, combine figure 2 and 3 , the content of p-cymene ...

Embodiment 2

[0044] A method for preparing p-cymene by dipentene, comprising the following steps:

[0045] S1, mix powdery palladium carbon catalyst (mass content of palladium 5-7wt%) and stainless steel θ ring filler with a mass ratio of 1:1, naturally pack in a fixed-bed reactor whose body is a temperature-resistant glass tube, and assemble A good gas phase reaction device; nitrogen gas is introduced at a low speed to exhaust the air in the device and maintain continuous access;

[0046] S2. Heating to bring the temperature inside the vaporizer to 180°C. The outer surface of the fixed bed reactor is wound with an electric heating belt to heat the fixed bed to 180°C. Add industrial dipentene dropwise to the vaporizer at a rate of 0.05mL / s. , when steam reaches the top of the fixed-bed reactor, turn on the vacuum pump and maintain the internal vacuum of the device at 0.09MPa, collect the liquid product, and analyze the content of p-cymene in the product by gas chromatography to be 92.14%. ...

Embodiment 3

[0048] A method for preparing p-cymene by dipentene, comprising the following steps:

[0049] S1, mix powdery palladium carbon catalyst (mass content of palladium 5-7wt%) and stainless steel θ ring filler with a mass ratio of 1:1, naturally pack in a fixed-bed reactor whose body is a temperature-resistant glass tube, and assemble A good gas phase reaction device; nitrogen gas is fed at a low speed to exhaust the air in the device and keep feeding continuously; it should be noted that the powdered palladium-carbon catalyst is a catalyst in which palladium is loaded on the carrier activated carbon.

[0050] S2. Heating to bring the temperature inside the vaporizer to 200°C. The outer surface of the fixed bed reactor is wound with an electric heating belt to heat the fixed bed to 180°C. Add industrial dipentene dropwise to the vaporizer at a rate of 0.1mL / s. , when steam reaches the top of the fixed-bed reactor, turn on the vacuum pump and maintain the internal vacuum of the devi...

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Abstract

The invention relates to a method for preparing p-cymene from dipentene. The method comprises the following steps of: S1, continuously introducing nitrogen into a fixed bed reactor, wherein a catalystbed layer is arranged in the fixed bed reactor, and the catalyst bed layer is theta-ring filler loaded with a powdery catalyst; S2, vaporizing dipentene at 180-220 DEG C to form steam, introducing the steam into the fixed bed reactor, filling the fixed bed reactor with the steam, and vacuumizing, wherein the temperature in the fixed bed reactor is 180-240 DEG C, and the vacuum degree is 0.04-0.095 MPa; and continuously introducing the steam into the fixed bed reactor to carry out catalytic dehydrogenation reaction to obtain p-cymene. According to the method, high-purity p-cymene can be simply, efficiently and continuously prepared, and the content of p-cymene is 92% or above.

Description

technical field [0001] The invention relates to the technical field of generating p-cymene, in particular to a method for preparing p-cymene from dipentene. Background technique [0002] my country has abundant turpentine resources, and the annual output of high-grade turpentine is about 80,000 tons. The deep-processing high-grade turpentine is mainly used to prepare camphor and terpineol, and industrial dipentene is the main by-product in the process of preparing the above products, and the annual output is relatively large. At present, industrial dipentene is mainly used as a solvent for paint and recycled rubber, with a low degree of utilization and low economic value. [0003] Industrial dipentene is mainly composed of monocyclic terpene compounds such as dipentene (limonene), pinene, terpinene, and terpinene. These compounds have the same or similar carbon skeleton structure as p-cymene. Molecules contain double bonds or conjugated double bonds, and some also contain ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C5/367C07C15/02
CPCC07C5/367C07C2523/44C07C15/02
Inventor 杨国恩李超凡蔡万雄吴志平
Owner CENTRAL SOUTH UNIVERSITY OF FORESTRY AND TECHNOLOGY
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