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Method for nitrifying nitrobenzene by using micro-channel continuous flow reactor

A technology of p-nitrobenzene and a reactor is applied in the field of nitration of p-nitrobenzene by using a microchannel continuous flow reactor, and can solve the problems of increased dilute sulfuric acid treatment capacity, increased sulfuric acid consumption, low availability and the like, Achieve the effect of reducing pollution, prolonging service life and low corrosion degree

Inactive Publication Date: 2020-07-10
沈阳感光化工研究院有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, because the availability of dilute sulfuric acid is not high, the consumption of sulfuric acid is doubled, and the treatment capacity of dilute sulfuric acid is also increased.

Method used

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  • Method for nitrifying nitrobenzene by using micro-channel continuous flow reactor

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0038] Mixed acid preparation: Mix 92% sulfuric acid and 65% nitric acid to get mixed acid, wherein the molar ratio of nitric acid to sulfuric acid is 1:4.

[0039] Set the temperature of the external heat exchanger to 85°C, that is, the preheating temperature is 85°C, so that the circulation temperature of the system reaches equilibrium.

[0040] The nitrobenzene and the mixed acid are respectively passed into the preheating module through the tetrafluoro advection pump for preheating, and then enter the reaction module of the microchannel continuous flow reactor. Adjust the flow rate of nitrobenzene to 1.7mL / min, adjust the flow rate of mixed acid to 5.1mL / min, make the molar ratio of nitrobenzene to nitric acid 1:1.05, control the residence time of reactants in the reactor to 80s, and let the reaction products flow into the collection tank , in order to make the reaction run continuously for 24 hours, there are 6 collection tanks in this example, each collection tank contin...

Embodiment 2

[0044] Mixed acid preparation: Mix 92% sulfuric acid and 65% nitric acid to get mixed acid, wherein the molar ratio of nitric acid to sulfuric acid is 1:5.

[0045] Set the temperature of the external heat exchanger to 85°C so that the circulating temperature of the system reaches equilibrium.

[0046] The nitrobenzene and the mixed acid are respectively passed into the preheating module through the tetrafluoro advection pump for preheating, and then enter the reaction module of the microchannel continuous flow reactor. Adjust the flow rate of nitrobenzene to 1.8mL / min, adjust the flow rate of mixed acid to 7.7mL / min, make the molar ratio of nitrobenzene to nitric acid 1:1.25, control the residence time of reactants in the reactor to 56s, and let the reaction products flow into the collection tank , In this example, the reactants collected continuously for 4 hours were collected, cooled to 50-60°C, added o-nitrotoluene, stirred evenly, cooled naturally, and left to stand for 1...

Embodiment 3

[0050] Mixed acid preparation: Mix 92% sulfuric acid and 65% nitric acid to get mixed acid, wherein the molar ratio of nitric acid to sulfuric acid is 1:6.

[0051] Set the temperature of the external heat exchanger to 85°C so that the circulating temperature of the system reaches equilibrium.

[0052] The nitrobenzene and the mixed acid are respectively passed into the preheating module through the tetrafluoro advection pump for preheating, and then enter the reaction module of the microchannel continuous flow reactor. Adjust the flow rate of nitrobenzene to 1.9mL / min, adjust the flow rate of mixed acid to 8.0mL / min, make the molar ratio of nitrobenzene to nitric acid 1:1.05, control the residence time of reactants in the reactor to 55s, and let the reaction products flow into the collection tank , continuously collected the reactants for 4 hours, cooled to 50-60°C, added p-difluorobenzene, stirred evenly, cooled naturally, and stood for 1 hour. The lower inorganic phase flo...

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Abstract

The invention discloses a method for nitrifying nitrobenzene by using a micro-channel continuous flow reactor, and belongs to the technical field of preparation of chemical intermediates. The method specifically comprises the following steps: 1, preparing 65% nitric acid and 92% sulfuric acid into mixed acid according to a molar ratio of 1:3.0-10.0; 2, respectively inputting nitrobenzene and the mixed acid into a micro-channel continuous flow reactor for preheating, wherein the molar ratio of nitric acid in the nitrobenzene to nitric acid in the mixed acid is 1:1.05-1.25; 3, making the preheated nitrobenzene and the mixed acid enter a reaction module for reaction for 30-120s, and letting the reactants enter a collecting tank; and 4, performing cooling to 50-70DEG C, adding an organic solvent, stirring the substances uniformly, performing standing for layering to obtain an organic layer at the upper layer and an inorganic layer at the lower layer, and respectively conveying the organiclayer and the inorganic layer into an organic storage tank and an inorganic storage tank. According to the invention, the concentrations of nitric acid and sulfuric acid are reduced; and the added organic solvent does not reduce the concentration of sulfuric acid in the process of separating dinitrobenzene from sulfuric acid, thereby achieving the goal of sulfuric acid reutilization.

Description

technical field [0001] The invention belongs to the technical field of preparation of chemical intermediates, in particular to a method for nitrating nitrobenzene using a microchannel continuous flow reactor. Background technique [0002] The renitrification product of nitrobenzene is a mixture of m-dinitrobenzene, o-dinitrobenzene and p-dinitrobenzene. It is a bulk intermediate with a global annual output of about 200,000 tons. However, the chemical properties of a single dinitrobenzene or a mixture of the above three dinitrobenzenes are quite active, and there is a risk of explosion during production, storage, transportation and use, especially during the production process Larger, because the nitration reaction heat of nitrobenzene is very large (155.03kJ / mol). As a comparison, the sulfonation reaction heat of benzene is only 18.61kJ / mol (Gao Xiqing, Chemistry and Technology of Alkylbenzene Sulfonation, Daily Chemical Information, 1978, (1): 1-9). For this reason, the na...

Claims

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Application Information

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IPC IPC(8): C07C201/08C07C205/06B01J19/00
CPCC07C201/08B01J19/0093C07C205/06
Inventor 李善柱祁咏梅沈困知茆勇军王晗张龙沈永嘉张秀岩
Owner 沈阳感光化工研究院有限公司
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