Adsorption of 1,2-dichloroethane on ZSM-5 and desorption dynamics by in situ synchrotron powder X-ray diffraction

The adsorption/desorption behaviour of ZSM-5 loaded with 1,2-dichloroethane was studied using the in situ synchrotron X-ray powder-diffraction technique in the temperature range 30°–600 °C. Rietveld refinements allowed to monitor the DCE decomposition process as well as the structural modifications undergoing on ZSM-5 upon a temperature-programmed thermal treatment. These results clearly demonstrated that regeneration of ZSM-5 is effective when thermally treating the adsorbent at about 300 °C thus minimising the cost of the regeneration step of the adsorption process. Once regenerated and reloaded the Rietveld refinement indicates that both DCE location and content remain substantially unchanged thus confirming ZSM-5 is able to re-adsorb DCE in amounts comparable to that adsorbed in the first cycle, in very good agreement with the chromatographic results. In conclusion, the use of this adsorbent with unchanged adsorption performances after thermal regeneration under mild conditions appears very promising also over several cycles of the adsorption/desorption process.