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Device and method for preparing high purity m/p-nitrotoluene by coupling rectification and crystallization

A technology for p-nitrotoluene and nitrotoluene, which is applied in the field of preparation devices for aromatic hydrocarbon isomer m-(p-)nitrotoluene, can solve the problems of unusable, difficult separation, poor product quality and the like, and achieves The effect of convenient operation, reasonable process and simple structure

Inactive Publication Date: 2011-07-20
JIANGSU HUAIHE CHEM
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

The separation of mononitrotoluene usually adopts five-tower or seven-tower rectification technology, especially the separation between p-nitrotoluene and m-nitrotoluene is very difficult, the operation is complicated, the energy consumption is high, the product quality is poor, and there are many problems. The products produced can only be used to manufacture low-standard products, and sometimes they can’t even be used, so it brings a lot of trouble to users. This situation also seriously restricts the development of my country’s medicine and related new materials

Method used

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  • Device and method for preparing high purity m/p-nitrotoluene by coupling rectification and crystallization
  • Device and method for preparing high purity m/p-nitrotoluene by coupling rectification and crystallization

Examples

Experimental program
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Embodiment 1

[0017] Embodiment 1: prepare p-nitrotoluene and meta-nitrotoluene according to the following steps: 1. The raw material is crude nitrotoluene, which contains ortho-nitrotoluene, para-nitrotoluene and meta-nitrotoluene Toluene, of which the boiling point of o-nitrotoluene is 222.3°C, the boiling point of m-nitrotoluene is 231.9°C, and the boiling point of p-nitrotoluene is 238.5°C, which will contain p-nitrotoluene after being separated by a vacuum distillation tower. The crude nitrotoluene mixture of toluene and m-nitrotoluene is sent to the rectification tower (6) with high-efficiency wire mesh packing inside through the raw material pipeline (1), and is evaporated by the falling film reboiler (7). The vapor-liquid phase exchange is continuously carried out in the column of the rectification tower, and a low-boiling-point steam with a high content of m-nitrotoluene is formed at the top of the tower. After the steam is condensed by the top condenser (8), part of the steam is re...

Embodiment 2

[0020] Embodiment 2: The steps are the same as in Example 1, wherein, the pressure inside the rectification tower: 125Pa, the temperature at the bottom of the rectification tower: 172°C, the temperature at the top of the rectification tower: 145°C, the mass concentration of m-nitrotoluene crystallizer feed: 92 %, m-nitrotoluene crystallizer cooling temperature: 0~10℃, p-nitrotoluene crystallizer feed mass concentration: 88%, p-nitrotoluene crystallizer cooling temperature: 5~30℃, crystallization cooling rate: 1~2℃ / hour, crystallizer sweating heating rate: 1~2℃ / hour.

Embodiment 3

[0021] Embodiment 3: The steps are the same as in Example 1, wherein, the pressure inside the rectification tower: 200Pa, the temperature at the bottom of the rectification tower: 185°C, the temperature at the top of the rectification tower: 165°C, the mass concentration of m-nitrotoluene crystallizer feed: 96 %, m-nitrotoluene crystallizer cooling temperature: 0~10℃, p-nitrotoluene crystallizer feed mass concentration: 95%, p-nitrotoluene crystallizer cooling temperature: 5~30℃, crystallization cooling rate: 1~2℃ / hour, crystallizer sweating heating rate: 1~2℃ / hour.

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Abstract

The invention discloses a device and method for preparing high purity m / p-nitrotoluene by coupling rectification and crystallization. In the device disclosed by the invention, a negative pressure rectifying tower (6) is connected with a raw material pipeline (1), a condenser (8) is arranged in the top of the negative pressure rectifying tower (6), the bottom of the condenser (8) is connected with an m-nitrotoluene crystallizer (11) through an m-nitrotoluene enriching pipeline (15), an m-nitrotoluene mother liquor (12) is connected with the negative pressure rectifying tower (6), the negative pressure rectifying tower (6) is connected with a vacuum pump (14) through a negative pressure pipeline (14), the bottom of the negative pressure rectifying tower (6) is connected with a falling film reboiler (7) and a circulating pump (9) through a pipeline, the falling film reboiler (7) is connected with a p-nitrotoluene crystallizer (2) through a p-nitrotoluene enriching pipeline (10), and a p-nitrotoluene mother liquor pipeline (4) is communicated with the negative pressure rectifying tower (6). The device disclosed by the invention has reasonable structure, simple process and low comprehensive energy consumption, is convenient in operation and is an ideal preparation device of high purity m / p-nitrotoluene.

Description

technical field [0001] The present invention relates to a preparation device and method of aromatic hydrocarbon isomer m-(p)nitrotoluene, especially a device and method for preparing high-purity m-(p-)nitrotoluene by coupling rectification and crystallization. Separation of para and meta isomers in mononitrotoluene. Background technique [0002] Mononitrotoluene includes three isomers of o-nitrotoluene, m-nitrotoluene and p-nitrotoluene, which are widely used in medicine, pesticides, dyes, rubber additives, new materials and other industries. With the advancement of science and technology, industrial development, especially the development of special drugs and new materials, the purity requirements for basic raw materials (such as p-nitrotoluene, m-nitrotoluene) are also getting higher and higher (up to 99.9%), so the preparation of high The purity of nitrotoluene raw materials is even more important. The separation of mononitrotoluene usually adopts five-tower or seven-to...

Claims

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Application Information

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IPC IPC(8): C07C205/06C07C201/16B01D3/10B01D7/02
Inventor 董云
Owner JIANGSU HUAIHE CHEM
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