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Synthetic method and special equipment for nitrobenzene

A synthesis method and technology of nitrobenzene, applied in the preparation of nitro compounds, organic chemistry, etc., can solve the problems of low conversion rate of benzene nitration, achieve the effects of short start-up and shutdown time, increase selectivity, and avoid process fluctuations

Inactive Publication Date: 2009-12-30
DALIAN INST OF CHEM PHYSICS CHINESE ACAD OF SCI
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Problems solved by technology

[0006] Although the conversion rate of benzene nitration is low in mixed acid with high water concentration, the microreactor is a micro-scale structure that can promote the mixing between organic matter and mixed acid, so the outlet product of the microreactor is highly dispersed, including unreacted benzene

Method used

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  • Synthetic method and special equipment for nitrobenzene
  • Synthetic method and special equipment for nitrobenzene

Examples

Experimental program
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Effect test

Embodiment 1

[0043] take attached figure 1 As shown in the nitrification process, the mixed acid is pumped to the micro mixer to prepare the nitrification mixed acid, and a mixed acid of sulfuric acid and nitric acid containing 68.5wt% sulfuric acid, 13.2wt% nitric acid and 18.3wt% water is prepared, and the mixed acid flows into the micromixer together with benzene reactor. The channel volume of the microreactor is 154 microliters, the mass ratio of nitric acid to benzene is 1.04, and the liquid hourly space velocity based on the total amount of benzene and mixed acid is 2400h -1 . Due to the exothermic process of the nitration reaction, the product temperature at the outlet of the microreactor is 39.8°C; a section of the nitration product stream enters the stirred reactor and is stirred for 30 minutes under normal pressure and at a speed of 200 rpm. Operate at room temperature. The organic phase in the product is washed with water, alkali and water until neutral to obtain a nitrobenze...

Embodiment 2

[0046] Process and technology are with embodiment 1. Only the molar ratio of nitric acid to benzene, the key reaction material, was changed to 1.16. The pump was run for 10 minutes and stirred for 30 minutes. Because the amount of nitric acid is slightly higher than that of Example 1, the highly dispersed primary nitration product has a temperature of 51° C. at the outlet of the microreactor.

[0047] The obtained total conversion of benzene was 99.92 mol%, and the selectivity of nitrobenzene was 99.85 mol%.

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Abstract

The invention relates to a combined nitrification method for synthesizing nitrobenzene and a combined device of a micro-reactor and a stirring reactor. During the synthesis, benzene and mixed acid of nitric acid and sulfuric acid are taken as initial materials, are conveyed to two inlets of the micro-reactor through a metering pump respectively, are premixed in micro-channels, and perform partialnitration reaction at the same time; and a first-stage nitration product with high dispersion state is produced at an outlet of the micro-reactor. The first-stage nitration product continuously flowsinto a stirred tank nitration reactor to continue to react. The method and the device perform continuous operation under the condition of the mixed acid with high water content and have safe process,the conversion rate of the benzene is 99.85 percent (mol), and the selectivity of a product, namely the nitrobenzene is 99.8 percent (mol).

Description

technical field [0001] The invention relates to a method for synthesizing high-purity nitrobenzene by nitrating benzene with a mixed acid of nitric acid and sulfuric acid, and a special device for realizing the method. combined in a nitration reactor. It belongs to the field of aromatic hydrocarbon nitration and new nitration process equipment. Background technique [0002] Nitrobenzene is an important dye and pharmaceutical intermediate, mainly used in the production of aniline. In the industry, it is produced by nitrating benzene with mixed acid with lower concentration of nitric acid and sulfur, and the nitration reactors used are mostly mechanically stirred reactors, and multiple reactors need to be operated in series (generally 3 to 4). This multi-tank series nitration process has uneven mixing, which is prone to local overheating of the materials in the tank. The direct impact is that the yield of the product nitrobenzene is not high, generally only 96-98.5% at the h...

Claims

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Application Information

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IPC IPC(8): C07C205/06C07C201/08
Inventor 陈光文焦凤军赵玉潮袁权李恒强初建胜
Owner DALIAN INST OF CHEM PHYSICS CHINESE ACAD OF SCI
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