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Low-ammonia-consumption caprolactam production process

A production process, a technology of caprolactam, applied to the preparation of lactam, calcium/strontium/barium sulfate, organic chemistry and other directions, can solve the problems of difficult industrial implementation, few recycling and replacement, complicated processes, etc. Economic benefits and the effect of reducing ammonia consumption

Active Publication Date: 2019-02-01
ZHEJIANG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In order to obtain α-type hemihydrate gypsum, it is necessary to add a variety of auxiliary chemical reagents, including the addition of sulfuric acid to adjust the pH value, and the addition of crystallization agents such as aluminum potassium sulfate and sodium citrate, etc. The process is complicated, the cost is high, and industrial implementation is difficult.
In particular, the patent does not say much about the recovery of process-generated ammonia

Method used

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  • Low-ammonia-consumption caprolactam production process
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  • Low-ammonia-consumption caprolactam production process

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0039] The crystallization law of the mixed reaction of ammonium sulfate and milk of lime was investigated experimentally in a 2L stirred tank. First in the stirred tank, the concentration of 900ml is 1.1mol / L of Ca(OH) 2 solution, mechanically stirred, and the outer jacket of the reactor was passed into heat conduction oil to heat and control the temperature, and the temperature was controlled at 100°C; then, 450ml concentration of 2.0mol / L (NH 4 ) 2 SO 4 The solution (21.2wt%) is poured into the reactor rapidly at one time, and the milk of lime remains excessive, and is uniformly mixed through mechanical stirring. After the reaction started, the pH value, the calcium ion concentration and the sulfate ion concentration of the measured solution were regularly sampled, and the crystal form and the particle size of the gypsum crystals generated by the sample analysis were analyzed simultaneously. During the reaction process, the nitrogen gas of 50ml / min is blown into the liqu...

Embodiment 2

[0041] The same as in Example 1, in a 2L stirred tank, the crystallization law of the mixed reaction of ammonium sulfate and milk of lime was experimentally investigated. The reaction temperature considered was also 100°C. The difference was the feeding method, and the milk of lime was added to sulfuric acid at one time under stirring conditions in ammonium solution. It is 2.0mol / L (NH 4 ) 2 SO 4 solution (21.2wt%), and then 900ml of Ca(OH) with a concentration of 1.1mol / L 2 The solution is poured into the reactor quickly at one time, and the milk of lime is kept in excess, and mechanical stirring is added to keep mixing evenly, and the nitrogen gas of 50ml / min is blown into the liquid phase simultaneously. After reacting for 60min, the ammonium ion concentration in the tail gas absorption bottle was sampled and analyzed, and the ammonium sulfate that added was used as a benchmark to calculate the ammonia recovery rate of 98.5wt%, indicating that ammonia was completely reco...

Embodiment 3

[0043] The same as in Example 1, in a 2L stirred tank, the crystallization law of the mixed reaction of ammonium sulfate and milk of lime was experimentally investigated. The difference was the reaction temperature and feeding method. The reaction temperature was 120 ° C. Under stirring conditions, the ammonium sulfate solution was pumped Continuously added to milk of lime. 900ml of Ca(OH) with a concentration of 1.1mol / L is charged into a 2L stirred tank earlier. 2 solution, and then 450ml concentration of 2.0mol / L (NH 4 ) 2 SO 4 Solution (21.2wt%) is continuously added in the reactor with the flow rate of 50ml / min, and ammonium sulfate solution has been added in 9 minutes, adds mechanical stirring and keeps mixing evenly, simultaneously the nitrogen gas of 50ml / min is blown into liquid phase. The jacket of the reactor was heated by heat conduction oil, and the temperature was controlled at 120°C. After reacting for 60min, the ammonium ion concentration in the tail gas ab...

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Abstract

The invention discloses a low-ammonia-consumption caprolactam production process. Firstly, a saturated ammonium sulfate aqueous solution which is a byproduct in a caprolactam production process is mixed with a lime milk solution, and a reaction is carried out to generate an ammonia-enriched gas phase and calcium sulfate precipitate-enriched water slurry; steam stripping deamination treatment is carried out on the calcium sulfate precipitate-enriched water slurry generated by the reaction, then ammonia-containing steam obtained by steam stripping is sent to an ammonia recovery step, and the deammoniated slurry is sent to a gypsum recovery step; high-concentration ammonia water and ammonia gas are recovered from the ammonia-containing steam obtained by the steam stripping deamination and theammonia-containing gas phase generated by the reaction through a rectification and condensation method, and the recovered ammonia is sent back to the caprolactam production process to be used as neutralization ammonia; and finally a high-quality gypsum product is recovered from the calcium sulfate precipitate-containing slurry subjected to the steam stripping deamination. Through the adoption ofthe technical scheme, an outlet problem of the ammonium sulfate byproduct can be solved, meanwhile, ammonia consumption in the caprolactam production process can be greatly reduced, and economic benefits of a caprolactam device can be improved.

Description

technical field [0001] The present invention proposes an improved method for producing caprolactam, which converts the by-product ammonium sulfate in the caprolactam production process into ammonia and calcium sulfate, and returns the ammonia to the caprolactam production process for recycling, which is a low ammonia consumption caprolactam production process and method. Background technique [0002] Caprolactam is a monomer for the production of nylon (nylon 6 fiber) and nylon 6 engineering plastics, also known as ε-caprolactam. A typical caprolactam production process (CN102675176A) includes four steps: 1) Ammoximation reaction: under the action of a catalyst, ammonia is oxidized by hydrogen peroxide to form hydroxylamine, and hydroxylamine and cyclohexanone undergo a non-catalyzed reaction to generate cyclohexanone oxime; 2) rearrangement reaction: cyclohexanone oxime containing 10% SO 3 In the presence of oleum, a Beckmann molecular rearrangement reaction occurs, and a ...

Claims

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Application Information

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IPC IPC(8): C01F11/46C07D223/10C07D201/06
CPCC01F11/46C01P2002/72C01P2004/61C07D201/06C07D223/10
Inventor 成有为秦伟潘腾王丽军李希
Owner ZHEJIANG UNIV
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