Parameter Effects on Dynamic Adsorption of Trichloroethylene on Hypercrosslinked Polymeric Adsorbents

Abstract

Fixed-bed column adsorption is an important operation for separation of gas mixtures and recovery of volatile organic compounds (VOCs). In industrial processes, the exothermal characteristic of adsorption could cause increasing of bed temperature, lead to bed combustion incidents and reduce adsorption capacity. In this work, the widely applied hypercrosslinked polymeric adsorbents (HPA) were chosen as adsorbent. The parameters [VOCs concentrations, flow rate, ratio of column height and diameter (H/D), and temperature] that affect adsorption performance were analyzed and investigated in the dynamic adsorption of trichloroethylene (TCE). Under isothermal conditions, breakthrough adsorption capacities decreased with increasing of temperature and inlet flow rate. Ratio of H/D should be set above 2∶1. Dynamic adsorption rate increases with increase of TCE concentration and temperature, and decreases with the increase of flow rate and H/D. Under near-adiabatic conditions, temperature in the column naturally increased, resulting in lower adsorption capacity and higher adsorption rate; in addition, the maximum temperature, which increased with TCE concentration, was approximate for different height measurements at central axial, but decreased for higher detected height at peripheral axial. Because of the thermal conductivity, the temperature was lower at peripheral axial than central axial. Finally, water vapor, used to regenerate the saturated bed, could help reduce the bed temperature and then slow the adsorption rate. However, water vapor was only advantageous for TCE adsorption at relative humidity lower than 50%. At higher relative humidity (80%), water molecules could occupy adsorption volume of TCE and reduce the adsorption capacity of TCE.