Method for preparation of 2, 5-dichloronitrobenzene by continuous nitration
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A technology of dichloronitrobenzene and p-dichlorobenzene, which is applied in 2 fields, can solve the problems of large amount of waste acid circulating and the existence of an emulsified layer at the interface of oil phase and acid phase, and achieves improved reaction modulus, stable product quality, and improved equipment. compact effect
Active Publication Date: 2016-11-09
江苏拓孚工程设计研究有限公司
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[0005] Aiming at the problems that the current 2,5-dichloronitrobenzene production process is not fully continuous, the waste acid circulation is large, and there is an emulsified layer at the interface of the oil phase and the acid phase, the invention provides a continuous nitration to prepare 2,5-dichloronitrobenzene The method of nitrobenzene adopts continuous nitration to prepare 2,5-dichloronitrobenzene. This method adopts automatic control, cancels the mixed acid preparation process, simplifies the process flow, and can realize continuous nitration reaction, continuous separation of nitration liquid and Continuous waste acid extraction
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Embodiment 1
[0024] 1. The production device is composed of 3 nitration kettles and 1 extraction kettle. The total volume of the 3 nitration kettles is 2.5m3 and 1.5m3 respectively. 3 、1.5m 3 , the effective volume is: 1.2m 3 、1.1m 3 、1.1m 3 ;The total volume of the extraction kettle is 1.5m 3 , the effective volume is 1.1m 3 , process control 1 # Nitrification tank temperature 58 ~ 62 ℃, 2 # Nitrification tank temperature 65 ~ 68 ℃; 3 # The temperature of the nitration tank is 65-68°C; the temperature of the extraction tank is 68-70°C; the reaction modulus is 3-4, and the concentration of sulfuric acid is 82-83%. Enter 320L / h p-dichlorobenzene to the extraction kettle, and the acidic p-dichlorobenzene flows into the extraction kettle for 1 # Nitrification kettle, to 1 # 175L / h of 97% sulfuric acid and 120L / h of 98% nitric acid are fed into the nitrification kettle, and the nitrification liquid is successively lifted to the next level of nitrification kettle through the lifters of...
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Abstract
The invention discloses a method for preparation of 2, 5-dichloronitrobenzene by continuous nitration. The method comprises the steps of: adopting three-stage kettle type continuous reaction, adding sulfuric acid, nitric acid and p-dichlorobenzene in an extraction kettle into a first stage nitrification kettle simultaneously to carry out nitrification reaction, letting nitrification liquid enter a next stage nitrification kettle through self-carried raisers of all nitrification kettles in order to react, at the end of reaction in a third stage nitrification kettle, separating an oil phase and an acid phase, carrying out neutralization, washing and dehydration on the oil phase so as to obtain 2, 5-dichloronitrobenzene, internally recycling part of waste acid in the acid phase back to the first stage nitrification kettle, letting the residual waste acid enter an extraction kettle, and performing p-dichlorobenzene extraction, and then conducting separation to obtain acidic p-dichlorobenzene and extracted waste acid, concentrating the extracted waste acid into concentrated sulfuric acid, and making the concentrated sulfuric acid and acidic p-dichlorobenzene enter the first stage nitrification kettle for recycling. The method provided by the invention adopts automation control, cancels a mixed acid preparation procedure, simplifies the technological process, can realize continuous nitrification reaction, continuous nitrification liquid separation and continuous waste acid extraction.
Description
technical field [0001] The invention belongs to the field of synthesis of 2,5-dichloronitrobenzene, and relates to a method for preparing 2,5-dichloronitrobenzene through continuous nitration. Background technique [0002] 2,5-Dichloronitrobenzene is an important chemical intermediate, mainly used in the production of 2,5-dichloroaniline, scarlet-based GG, red-based 3GL, red-based RL and trichloronew (2,4,4 - trichloro-2-hydroxydiphenyl ether), etc., in addition, it can also be used as a nitrogen fertilizer synergist to increase rice yield. [0003] At present, the industrialized production of 2,5-dichloronitrobenzene adopts a batch production process, using sulfuric acid as the base acid, adding p-dichlorobenzene, then adding nitric acid and sulfuric acid mixed acid for nitration, neutralization, washing, and dehydration to obtain 2,5-dichloronitrobenzene. 5-dichloronitrobenzene products. The batch production process has a series of problems such as low production capacit...
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