Study On The Disubstituted Aromatic Nitration In A Microchannel Reactor

Aromatic nitration has been existed many problems, such as poor safety, serious waste pollution, etc. Using the microreactor technology, it has effective capability of heat transfer and mass transfer and fluid mixing, to achieve green nitration of aromatic hydrocarbons. At the same time we tried to apply homogeneous catalysis system to the microreactor of the nitration of the disubstituted aromatic hydrocarbons.(1)Using nitric acid as nitrating agents, o-xylene as substrates, we detailedly studied on the nitration process of o-xylene in the microreactor system. Based on the factors such as reaction temperature, reaction time, reactant dosage, etc. We summarize the best nitration process of o-xylene in the the microchannel reactor:o-xylene and nitric acid molar ratio of1:2,the reaction temperature was60℃, the residence time of the liquid in the microchannel was48-64s, at this time the conversion of o-xylene was above80%, and the reaction selectivity was more than99.4%, the p/o ratio was improved to1.23. Nitration of o-xylene in micro reaction of system dynamics equation is:r=9.178x1O2xexp (-3630/T) x([HNO3]-12).(2)We combined the surfactant, the rare earth metal salt and the ionic liquid as catalyst with micro reaction system. Basing on previous experimental results, we investigated the application of new reaction catalytic systems in the microchannel reactor from the reactant conversion and product selectivity and catalyst recycling. With the catalysis of surfactant, o-xylene conversion rate reached93%, the p/o ratio reached2.87;With the catalysis of rare earth metal salt,, o-xylene conversion rate reached98%, p/o ratio was1.56; With the catalysis of the ionic liquid, o-xylene conversion rate reached96%, p/o value ratio was1.81. We used the catalytic process to the nitration of the disubstituted aromatic in the microreactor, found that conversion and aromatics selectivity compared to conventional reactors, have been improved to some extent. We studied nitration reaction mechanism of the catalytic system from NO2+theory, which provides a theoretical basis for the industrial application of valuable green nitration technology.