| Summary: | An efficient continuous-flow nitration process of <i>o</i>-xylene at pilot scale was demonstrated. The effects of parameters such as temperature, ratio of H<sub>2</sub>SO<sub>4</sub> to HNO<sub>3</sub>, H<sub>2</sub>SO<sub>4</sub> concentration, flow rate, and residence time on the reaction were studied. Under the optimal conditions, the yield of products reached 94.1%, with a product throughput of 800 g/h. The main impurities of this continuous-flow nitration process were also studied in detail. Compared with batch process, phenolic impurity decreased from 2% to 0.1%, which enabled the omission of the alkaline solution washing step and thus reduced the wastewater emission. The method was also successfully applied to the nitrification of <i>p</i>-xylene, toluene, and chlorobenzene with good yields.
|
|---|