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Process design of two-step mononitration of m-xylene in a microreactor

Process design of two-step mononitration of m-xylene in a microreactor In this study, m-xylene nitration was scaled up in a microreactor. The effects of temperature, molar ratio, and mass fraction of sulfuric acid on the two synthesis methods were systematically analyzed. The reaction temperature and mass fraction of sulfuric acid are the main factors influencing the generation of poly-nitro impurities when the mixed acid reacts with m-xylene. When the mixed acid is used as the nitrating agent, it is difficult to control the product selectivity and the yield of poly-nitro impurities by changing the reaction conditions. A two-step nitration method was designed to solve the problems of product selectivity and yield of poly-nitro impurities. In the first step, nitric acid is used as a nitrating agent to react with m-xylene. In the second step, sulfuric acid is added to the second microreactor. It acts as a catalyst to continue activating the nitric acid in the first step to react with the unconverted m-xylene. Under the optimal experimental conditions, the yield of mono-nitro products reached 99%, and throughput of 1 kg/h. It has good advantages for industrial production compared with other methods reported in the literature. The way presented in this study can provide a reference for the design of kilogram-scale synthesis with rapid and high exothermic reactions in microreactors. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Journal of Flow Chemistry Springer Journals

Process design of two-step mononitration of m-xylene in a microreactor

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Publisher
Springer Journals
Copyright
Copyright © Akadémiai Kiadó 2022
ISSN
2062-249X
eISSN
2063-0212
DOI
10.1007/s41981-022-00228-y
Publisher site
See Article on Publisher Site

Abstract

In this study, m-xylene nitration was scaled up in a microreactor. The effects of temperature, molar ratio, and mass fraction of sulfuric acid on the two synthesis methods were systematically analyzed. The reaction temperature and mass fraction of sulfuric acid are the main factors influencing the generation of poly-nitro impurities when the mixed acid reacts with m-xylene. When the mixed acid is used as the nitrating agent, it is difficult to control the product selectivity and the yield of poly-nitro impurities by changing the reaction conditions. A two-step nitration method was designed to solve the problems of product selectivity and yield of poly-nitro impurities. In the first step, nitric acid is used as a nitrating agent to react with m-xylene. In the second step, sulfuric acid is added to the second microreactor. It acts as a catalyst to continue activating the nitric acid in the first step to react with the unconverted m-xylene. Under the optimal experimental conditions, the yield of mono-nitro products reached 99%, and throughput of 1 kg/h. It has good advantages for industrial production compared with other methods reported in the literature. The way presented in this study can provide a reference for the design of kilogram-scale synthesis with rapid and high exothermic reactions in microreactors.

Journal

Journal of Flow ChemistrySpringer Journals

Published: Jun 8, 2022

Keywords: Microreactor; Two-step; nitration; m-xylene; Kilogram-scale

References