Adsorption of m-and p-chloronitrobenzene on FAU zeolites and its application on crystallization

Abstract

Adsorption isotherms of m- and p-chloronitrobenzene (CNB), isomeric substances on FAU zeolites with alkaline earth exchanged cations were studied under static conditions at 30°C. The experiment was carried out by preparing 1 to 8 wt% of m- and p-CNB in the solution. Hexane and dodecane were used as the solvent and tracer, respectively. The composition was determined by a gas chromatograph. The results further substantiated the adsorption behavior of CNBs on the FAU zeolites with the alkaline exchanged cations. The adsorption capacities of CNBs on both types of zeolite partly depended on the acid-base interaction. Normally, m-CNB was selectively adsorbed by the zeolites more than p-CNB due to a higher dipole moment or higher basicity. The adsorption capacities of m- and p-CNB on the zeolites with both the alkaline and the alkaline earth exchanged cations increased with the acid strength of the zeolite. NaY and CaY were the most appropriate adsorbent for CNBs separation because they offered the high adsorption capacity of CNBs and a high m -lp-CNB selectivity. Moreover, the FAU zeolites were also used in the crystallization of m- and p-CNB to study their effect on the precipitate composition.