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Process and system for continuous preparation of phenylenediamine

A preparation process, the technology of phenylenediamine, which is applied in the field of catalytic hydrogenation to synthesize aniline compounds, can solve the problems such as the danger of dinitrobenzene, and achieve low operating costs, less three wastes, and economically reasonable effects

Active Publication Date: 2019-10-25
江苏方圆芳纶研究院有限公司
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Storage of dinitrobenzene is dangerous

Method used

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  • Process and system for continuous preparation of phenylenediamine

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preparation example Construction

[0047] figure 1 It is a schematic diagram of the system composition of an embodiment of the preparation system of the present application, refer to below figure 1 The continuous preparation process and system of phenylenediamine of the present application will be described.

[0048] figure 1 Among them, the preparation system can be effectively applied to the continuous preparation process of, for example, phenylenediamine using benzene as a raw material, including a nitration unit, a washing unit, and a hydrogenation reduction unit connected in sequence through pipelines, and the nitration unit includes pipes connected in series Type reactor I1, phase separation device I7, tubular reactor II2 and phase separation device II8, the washing unit includes water washing tower I9, alkali washing tower 10 and water washing tower II20 connected in sequence, and the hydrogenation reduction unit includes The vertical pipe reactor III3, the first gas-liquid separator 11, the skeleton n...

Embodiment 1

[0053] A continuous preparation process of phenylenediamine, comprising the following steps:

[0054] 1) Nitric acid and sulfuric acid are mixed to form mixed acid I, and the mass percentage of said mixed acid I is composed of: 15% sulfuric acid, 75% nitric acid, and 10% water; benzene and mixed acid I are continuously fed into solids filled with 7g MCM-41 molecular sieves. React in the tubular reactor I of acid catalyst, the feed rate of benzene is 39 g / min, the feed rate of mixed acid is 44.1 g / min, the temperature of control tube reactor I is 35 ℃, and material is in tubular reaction After staying in the device Ⅰ for 1.3 hours, the material is discharged;

[0055] 2) The discharge obtained in step 1) is subjected to continuous phase separation to obtain acid phase I and organic phase I respectively, and the organic phase I and mixed acid II are continuously fed into a tubular reactor filled with 10 g of MCM-41 molecular sieve solid acid catalyst Ⅱ, the mass percentage of d...

Embodiment 2

[0065] A continuous preparation process of phenylenediamine, comprising the following steps:

[0066] 1) Mix nitric acid and sulfuric acid to form mixed acid I. The mass percentage of mixed acid I consists of: 20% sulfuric acid, 60% nitric acid, and 20% water; React in the tubular reactor I of acid catalyst, the feed rate of benzene is 46.8 g / min, the mixed acid I feed rate is 63 g / min, the temperature of control tube reactor I is 75 ℃, and the material is in the tubular reactor The material is discharged after staying in the reactor I for 0.2 hours;

[0067] 2) The discharge obtained in step 1) is continuously subjected to phase separation to obtain acid phase I and organic phase I respectively, and the organic phase I and mixed acid II are continuously sent into a tubular reactor filled with 10 g of HZSM-5 solid acid catalyst Ⅱ, the mass percentage of described mixed acid II is composed of: sulfuric acid 35%, nitric acid 60%, water 5%; The material is discharged after stay...

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Abstract

The invention discloses a process and a system for continuous preparation of phenylenediamine. With the process provided by the invention, benzene is used as a raw material; a solid acid catalyst is adopted; meanwhile, mixed acid is added; two-stage continuous nitration is performed; obtained mixed dinitrobenzene is directly subjected to two-stage continuous hydrogenation reduction without being separated; thus, the phenylenediamine is obtained. According to a scheme of the invention, a large amount of nitrobenzene and dinitrobenzene is not needed to be stored in the process; meanwhile, by adoption of a continuous pipeline reaction, a material is not accumulated, so possibility of sudden explosion is fundamentally eliminated; and the process is an intrinsically-safe preparation process forthe phenylenediamine.

Description

technical field [0001] The invention relates to a method for synthesizing aniline compounds by catalytic hydrogenation, in particular to a continuous preparation process and system of phenylenediamine. Background technique [0002] Nitrobenzene compounds are important fine chemical intermediates and can be widely used in dyes, medicines, pesticides and explosives. At present, the industry still adopts the traditional process of nitration under certain reaction conditions with benzene and nitric acid as raw materials and sulfuric acid as a catalyst. The disadvantage of this process is that a large amount of waste acid and waste water will be produced and need to be treated; in addition, for every 1 mole of nitrification reaction, the heat released is more than 100kJ, and the specific heat capacity of sulfuric acid is very small, and the temperature raised by heating sulfuric acid with the same heat is often It is three times higher than the temperature raised by heating wate...

Claims

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Application Information

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IPC IPC(8): C07C209/36C07C211/51C07C201/08C07C205/06
CPCC07C201/08C07C209/36C07C211/51C07C205/06
Inventor 王农跃赵全忠闻国强沙艳松许坚章冬霞韩杰李斌
Owner 江苏方圆芳纶研究院有限公司
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