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Continuously operated adiabatic method for producing nitrobenzene by nitration of benzene

A technology of nitrobenzene and nitration, which is applied in the direction of nitro compound preparation, chemical instruments and methods, sulfur compounds, etc., can solve the accumulation and clogging of phase separators and crude nitrobenzene heat exchangers, and cannot completely eliminate black substances, and cannot It has the feasibility of industrial application and other issues, so as to avoid the formation of black matter, improve the stable operation cycle and reduce the maintenance cost

Active Publication Date: 2021-06-11
WANHUA CHEMICAL (NINGBO) CO LTD +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

This patented technology helps reduce or eliminate problems caused by excessive buildup on equipment used for processing nitrosophenols during production processes such as manufacturing phenylthiazoanone (PHT). By adding an antioxidant called iron oxide into this system, it decomposes any remaining impurities that may be present with respect to PTHA without causing them to form unwanted deposits over other components inside the reactor. Additionally, there are no black residue left behind when removing purified benzenesulfonic acids after use. Overall, these technical improvements help improve the stability and lifespan of the devices involved in producing certain chemicals.

Problems solved by technology

Technological Problem: Current methods involve extracting pure ammonia gas through condensations involving different reactions like decomposition and reduction processes. However, these techniques may result in generating unwanted side products during purifying the resulting liquid mixtures containing harmful compounds due to incomplete removal of certain components. Additionally, some impurities could remain even if they were removed without being able to fully stop them altogether. Therefore, new ways must be developed to remove residual materials while maintaining stability within the equipment itself.

Method used

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  • Continuously operated adiabatic method for producing nitrobenzene by nitration of benzene

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Experimental program
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Effect test

Embodiment 1

[0036] Embodiment 1 (comparative embodiment)

[0037] The preparation of nitrobenzene was carried out as described in General conditions for the preparation of nitrobenzene. In the phase separation device, the suspended black oil droplets generated by the reaction accumulate in the nitrobenzene layer in the phase separator, and precipitate to form black solid particles at the flanges, gaskets and other equipment parts where the nitrobenzene layer is located in the phase separation device. The black solid particles flow through the crude nitrobenzene cooler along with the crude nitrobenzene, blocking the nitrobenzene cooler and causing the shutdown of the device. It is necessary to open the phase separator and the crude nitrobenzene cooler for cleaning 6-8 times a year.

Embodiment 2

[0038] Embodiment 2 (according to the present invention)

[0039] The preparation of nitrobenzene is carried out as described in the general conditions for the preparation of nitrobenzene, with the difference that the following additional measures are taken: the aqueous phase containing sulfuric acid (b1) obtained in the phase separator enters the sulfuric acid regenerator, the sulfuric acid regenerator Add reducing agent (C2) in, wherein reducing agent (C2) is sulfurous acid, reducing agent concentration is controlled at 1000ppm, obtains the aqueous phase (b1) containing sulfuric acid based on the mass meter of phase separator. Through long-term operation, no black matter was found in the phase separator and crude nitrobenzene cooler.

Embodiment 3

[0040] Embodiment 3 (according to the present invention)

[0041] The preparation of nitrobenzene is carried out as described in the general conditions for the preparation of nitrobenzene, with the difference that the following additional measures are taken: the aqueous phase containing sulfuric acid (b1) obtained in the phase separator enters the sulfuric acid regenerator, the sulfuric acid regenerator Add a reducing agent (C2) to the mixture, wherein the reducing agent (C2) is a mixture of sulfurous acid, thiosulfuric acid, and dithionous acid (the mass ratio of sulfurous acid, thiosulfuric acid, and dithionous acid is 1:1:1 ), the reducing agent concentration is controlled at 1000ppm, and the mass meter of the aqueous phase (b1) containing sulfuric acid is obtained based on the phase separator. Through long-term operation, no black matter was found in the phase separator and crude nitrobenzene cooler.

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Abstract

The invention relates to a continuously operated adiabatic process for producing nitrobenzene by nitration of benzene. After nitration is completed, crude nitrobenzene is separated from a water phase, obtained diluted sulfuric acid enters a sulfuric acid regenerator, a reducing agent is added into the sulfuric acid regenerator, and the reducing agent can decompose nitrophenol derivatization black substances dissolved in sulfuric acid and can prevent aromatic hydrocarbon and nitrous acid from forming resinified products at the same time, so the black substances are prevented from being generated in the nitration process. The regenerated sulfuric acid enters a sulfuric acid flash evaporator to remove impurities, so that the concentrated sulfuric acid is recovered and recycled.

Description

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Claims

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Application Information

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Owner WANHUA CHEMICAL (NINGBO) CO LTD
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