Zn-Modified Hβ Zeolites Used in the Adsorptive Removal of Organic Chloride from Model Naphtha

Different metal ions were used to modify Hβ zeolite adsorbents by an impregnation method to remove organic chlorides from the model naphtha. The dechlorination performance of different ion-modified adsorbents was evaluated using a microcoulometer. The effects of calcination time and temperature, metal loading, adsorption time and temperature, and dosage of adsorbent were investigated by batch adsorption experiments. The modified adsorbents were characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), NH₃-temperature-programmed desorption (TPD), scanning electron microscopy (SEM), infrared spectroscopy of pyridine adsorption (Py-IR), and X-ray photoelectron spectroscopy (XPS). After modification, the modified Zn/Hβ zeolite exhibited the best dechlorination performance among the other metal-loaded zeolites. The removal percentage of organic chloride of the Zn/Hβ adsorbent prepared at optimum preparation and adsorption conditions can reach 72.54%, compared with 34.07% of Hβ zeolite. The Zn/Hβ adsorbent also maintained good dechlorination performance after regeneration by calcination for five times. The characterization results revealed that the concentration of the B acid sites in the zeolite decreased with the introduction of the metals, whereas that of the L acid sites increased. Zn/Hβ zeolite had the lowest B/L ratio but the best dechlorination performance, which meant that the type and amount of acidic sites present in zeolites played a significant role in dechlorination performance and L acid was beneficial for chloride compound removal.