Crystallization of m-chloronitrobenzene in the presence of adsorbents

Abstract

Chloronitrobenzenes or CNBs, isomeric substances, consisting of o-, m-and p-CNB, are used as an important starting material in chemical production. This work explored the possibility of enhancing the CNBs separation through the combination of crystallization and adsorption. Effects of feed composition on the crystallization of m- and p-CNB were studied with 61 (below the eutectic composition) and 65 wt% (above the eutectic composition) m-CNB in the feed. In the experiments, the liquid mixture was cooled to its crystallization temperature, and the precipitate composition was determined by a gas chromatograph. The result showed that the precipitates from the feed without a zeolite were rich in p-CNB and m-CNB with the 61 wt% m-CNB and 65 wt% m-CNB in the feeds, respectively. On the contrary, the precipitates from the feed with FAU zeolites were rich in p-CNB for both below and above the eutectic composition. The effect of the number of FAU zeolites on the precipitate composition was then investigated. The results revealed that the precipitates from the lower number