Continuous dinitration of toluene to dinitrotoluene in a microreactor
In order to realize the safe and efficient production of dinitrotoluene(DNT),the behavior of toluene dinitration process was investigated by using microreaction technology with mixed acid as nitrating agent and toluene as raw material.Increasing the reaction temperature,elevating the molar ratio of nitric acid to toluene,reducing the water content of the mixed acid and decreasing N/S and integrating stirring were all conducive to the generation of DNT.Lowering the reaction temperature and increasing the water content of the mixed acid and the molar ratio of nitrate to sulfur are beneficial to reducing the 2,4-/2,6-DNT ratio.The nitrification process has been optimized for 80/20DNT products.At a reaction temperature of 75℃,a water content of mixed acid of 14%,N/S of 1/4 or 1/3,and a stirring time of 5 min,the product composition demonstrated desirable characteristics,i.e.,the content of MNT in the product was less than 0.2%,2,4-DNT and 2,6-DNT greater than 96%and other DNT less than 4%.More importantly,the ratio of 2,4-/2,6-DNT was less than 4.25.Under the conditions of adiabatic and room temperature feeding,a mixed acid water content of 14%,N/S of 1/4,and stirring time of 10 min,the product also complied with the industry standards.The study outcomes offer valuable technical insights for the continuous dinitration process of toluene and the continuous preparation of 80/20DNT products.
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