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Recycling method of nitrogen oxide gas in diazotization reaction process

A reaction process and nitrogen oxide technology, applied in chemical instruments and methods, separation methods, organic chemistry, etc., can solve problems such as the inability to realize waste gas recycling, and achieve the effect of solving environmental problems and improving economic benefits.

Pending Publication Date: 2022-04-05
NANJING UNIV OF SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, the nitrogen oxide gas treated by these methods is generally converted into non-toxic and harmless gas and discharged into the atmosphere, which cannot realize the recycling of waste gas

Method used

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  • Recycling method of nitrogen oxide gas in diazotization reaction process
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  • Recycling method of nitrogen oxide gas in diazotization reaction process

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0027] (1) NO X Gas absorption: Add 88 mL of 69 wt% sulfuric acid to a 250 mL two-necked flask, then add 11.8 g of m-nitroaniline, and stir to form a suspension; slowly dissolve 23 g of 36 wt% sodium nitrite solution Add dropwise to the two-necked flask. The NO produced during the dropping process X The gas is passed into an absorption bottle filled with 5 mL of concentrated sulfuric acid using a negative pressure device. The temperature of concentrated sulfuric acid was kept at 20°C. reabsorbed NO X Gas five times until all the concentrated sulfuric acid in the absorption bottle turns into solid. Heat the solid in the absorption bottle to dissolve, then take 10 μL of the sample and dissolve it in a small amount of concentrated sulfuric acid, transfer it to a 50 mL volumetric flask, continue diluting with concentrated sulfuric acid, and constant volume, the concentration is 222 mg measured by UV-Vis spectrometer / L, its ultraviolet characteristic peaks are as figure 1 . ...

Embodiment 2

[0031] (1) NO X Gas absorption: Add 88 mL of 69 wt% sulfuric acid to a 250 mL two-necked flask, then add 13.9 g of 3,5-dichloroaniline, and stir to form a suspension; 23 g of 36 wt% sulfuric acid The sodium nitrate solution was slowly added dropwise into the two-necked flask. The NO produced during the dropping process X The gas is passed into an absorption bottle filled with 5 mL of concentrated sulfuric acid using a negative pressure device. The temperature of concentrated sulfuric acid was kept at 30°C. reabsorbed NO X Gas five times until all the concentrated sulfuric acid in the absorption bottle turns into solid. The solid in the absorption bottle was heated and dissolved, and the sample was prepared, and the concentration was measured as 246 mg / L by an ultraviolet-visible spectrometer. After calculation, the mass fraction of nitrosyl sulfuric acid in the measured absorption liquid is 76%.

[0032] (2) Reuse of absorption liquid: add 22 mL of 69 wt% sulfuric acid i...

Embodiment 3

[0035] (1) NO X Gas absorption: Add 88 mL of 69 wt% sulfuric acid to a 250 mL two-necked flask, then add 13.0 g of 2-methyl-4-nitroaniline, and stir to form a suspension; 23 g of 36 wt% % sodium nitrite solution was slowly dropped into the two-necked flask. The NO produced during the dropping process X The gas is passed into an absorption bottle filled with 5 mL of concentrated sulfuric acid using a negative pressure device. The temperature of the concentrated sulfuric acid is maintained at 50°C. reabsorbed NO X Gas seven times, so that the concentrated sulfuric acid in the absorption bottle reaches the maximum adsorption capacity, take an appropriate amount of the absorption solution for sample preparation, and use the ultraviolet-visible spectrometer to measure its concentration as 309 mg / L. After calculation, the mass fraction of nitrosyl sulfuric acid in the measured absorption liquid was 96%.

[0036] (2) Reuse of absorption solution: Add 22 mL of 69 wt% sulfuric aci...

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Abstract

The invention belongs to the field of industrial waste gas treatment, and relates to a method for recycling nitrogen oxide gas in a diazotization reaction process. The method comprises the following steps: introducing NOX gas generated by reaction of a diazotization reagent into an absorption device filled with concentrated sulfuric acid until the content of nitroso sulfuric acid in absorption liquid is 60-96 wt%; placing primary arylamine in a sulfuric acid solution, stirring to form a turbid liquid, dropwise adding the obtained absorption liquid into the turbid liquid, and reacting to prepare a diazonium salt solution; the nitrogen oxide gas generated in the diazotization reaction process can be absorbed, the absorption liquid can still serve as a diazotization reagent to be applied to the diazotization reaction, waste gas recycling is achieved, the process is simple, and high economic benefits are achieved.

Description

technical field [0001] The invention relates to the field of gas treatment, in particular to a method for recycling nitrogen oxide gas in a diazotization reaction process. Background technique [0002] The diazotization reaction is a traditional chemical reaction, and the diazonium salt produced by the reaction can be widely used in the fields of polyphenol detection, biomedicine, food safety, and azo dye precursors. [0003] At present, the diazotization reagent used in industrial production is mainly sodium nitrite. For the preparation of some strong primary aramide diazonium salts, in the large-scale and continuous production process, the heat generated by the reaction is usually used to increase the reaction temperature and accelerate the reaction speed, thereby shortening the reaction time. This causes a large amount of sodium nitrite to decompose to generate NO during the reaction process. X exhaust gas. These gases will cause great harm to the human body and the na...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B01D53/77B01D53/56B01D53/14C07C245/20
Inventor 蔡春杜成义
Owner NANJING UNIV OF SCI & TECH
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