Method for synthesizing dinitrotoluene through micro-channel reactor

Abstract

The invention belongs to the field of chemical industry process, and particularly discloses a method for synthesizing dinitrotoluene through a micro-channel reactor. The method comprises the followingsteps: feeding a measured mixed acid, NO2 gas and methylbenzene into the micro-channel reactor to mix and react fully in proportion; after the reaction is ended, performing gas-liquid separation first, further oxidizing oxynitride in a gas phase, and returning the oxynitride to the system to participate in the reaction again; standing a liquid phase for layering; respectively measuring an organicphase, an aqueous phase and the NO2, feeding the organic phase, the aqueous phase and the NO2 into a secondary micro-channel reactor for reacting again, performing gas-liquid separation on a secondary reaction product again, further oxidizing the oxynitride in the gas phase, and returning the oxynitride to the system to participate in the reaction again; standing the liquid phase for layering; returning the aqueous phase to participate in the reaction; performing cooling, alkaline washing, drying and purifying on the organic phase to obtain the dinitrotoluene product. According to the method,concentrated sulphuric acid is taken as a catalyst, and nitric acid and the NO2 are taken as nitrating agents; the mixed acid after the reaction can be recycled and used directly without concentrating, so that equipment investment is reduced, and the production energy consumption is obviously reduced.

Description

Technical field [0001] The invention belongs to the field of chemical engineering, and is specifically a method for synthesizing dinitrotoluene in a microchannel reactor. Background technique [0002] Dinitrotoluene is a raw material for the preparation of toluene diisocyanate. It can also be used to produce dye intermediates, explosives, dye intermediates, and explosives. It is an important organic chemical intermediate. Dinitrotoluene is usually produced by the nitration of toluene, and the nitration reaction is a chemical reaction widely used in organic chemical industry. [0003] At present, the equipment used in the nitration reaction is usually a tank reactor or a loop reactor. During continuous production, multiple reactors are required in series. Although this reaction method realizes the continuous feeding and discharging of materials, the materials are in the reactor. The residence time is uneven, the unnitrate and overnitrate in the production process are not easy to co...

AI Technical Summary

Problems solved by technology

[0005] In addition, in the nitration reaction, if mixed acid is used as the nitrating agent, the combination of sulfuric acid and the water generated by the reaction will also release a large amount of heat, which intensifies the rising trend of temperature during the reaction process.

After the reaction, the concentration of the mixed acid decreases, and it needs to be concentrated before it can be returned to the system for reuse. Moreover, the temperature of the mixed acid concentration process is high, and the material corrodes the equipment seriously.

Images