Study On The Aromatic Nitration In A Microreactor

Aromatic nitration has always been a highly exothermic reation, poor safety and environment pollution. Using the novel microreactor technology, with its great specific surface area, small volume and excellent heat and mass transfer performance, we realized the precise control of aromatic nitration. The article based on the special microglass reactor as the core, established the microreaction system, which used in the aromatic nitration research.(1)Using nitric acid as nitrating agents, we detailedly studied on the nitration process of toluene in the microreactor system. By compared with the date obtained from the conventional reactor, in the optimization of conditions, the reaction time was shortened to 1/100, the conversion of toluene came up to 94.8%, the selectivity of mono-nitration was improved to 99.4%, the ortho-/para-(o/p) ratio was controlled in 1.29～1.34. Its applications in nitration of other simple aromatics showed that conversion and selectivity were superior to the conventional reactor, which proved the universality of the system. From the perspective of process evalution, we summarized the advantages of microreactor system applied in the aromatic nitration.(2)Introducing the homogeneous catalysts into the microreactor system, from the perspectives of conversion, reaction selectivity and the cycle catalytic system, we emphasised on the nitration of simple aromatics. In ionic liquids catalytic system, the conversion of toluene reached 94%, o/p ratio reduced to 1.25. After five recycling, the conversion of toluene was still above 88% and o/p ratio was less than 1.30. By compared to conventional reactor, the conversion of alkyl-benzenes increased to 90%, the conversion of halogenated-benzenes increased by more than 10%. In Lanthanide(iii) trifluoroacetate catalytic system, the conversion of toluene kept to 90%, o/p ratio reduced to 1.27. The conversion of alkyl-benzenes and halogenated-benzenes were increased about 15% and 10% versus batch reactor, while the para-selectivity of alkyl-benzenes and the ortho-selectivity of halogenated-benzenes were improved about 5% versus without catalysts. Finally, based on NO2+ theory, the article simply discussed the catalytic mechanism of nitration, completed the green nitration and regioselective mono-nitration of aromatics in the microreactor system, had theoretical and engineering practical significance.