Removal of Organochlorine from Model Oil Using Mg-Modified ZSM-5 Zeolite: Dechlorination Performance, Regeneration, and Thermodynamics

Various metal-modified ZSM-5 zeolite adsorbents prepared by the impregnation method were applied to the removal of organic chlorides from model naphtha. The adsorption performance and regeneration stability were investigated by static adsorption experiments. The morphologies, structural features, and physicochemical properties of the adsorbents were characterized by X-ray diffraction, Brunauer-Emmett-Teller analysis, NH3 temperature-programmed desorption, scanning electron microscopy, transmission electron microscopy, and pyridine adsorption infrared spectroscopy. The Mg/ ZSM-5 zeolite adsorbent possessed a relatively high specific surface area and good metal dispersion and exhibited the best dechlorination and regeneration performance. The characterization results revealed that introduction of the metal exerted a significant influence on the acidic properties of the catalyst surface. A decrease in the ratio of Bronsted acidic sites to Lewis acidic sites and an increase in the amount of moderately acidic sites were confirmed to be responsible for the excellent adsorption performance of the Mg-modified ZSM-5 zeolite. Furthermore, the Langmuir adsorption isotherm model was applied to study the adsorption equilibrium and thermodynamics of the Mg/ZSM-5 adsorbent under mild conditions. The results revealed that the removal of 1,2-dichloroethane by the Mg/ZSM-5 adsorbent was endothermic, spontaneous, disordered, and primarily involved physical adsorption.