Adsorption of benzothiophene over acid modified NaY zeolites

NaY-C and NaY-P adsorbents were successfully obtained through modifying parent NaY zeolite with citric acid and phosphate acid, respectively. The obtained adsorbents were characterized by scanning electron microscope, X-ray diffraction, X-ray fluorescence, N₂ sorption and temperature programmed desorption of NH₃. The mesopore surface area of the NaY-C adsorbent was increased when the parent NaY zeolite was modified by citric acid, with preserving he zeolite skeletal structure. Meanwhile, the decreased weak acid and increased strong acid content were observed in NaY zeolite modified with phosphate acid aqueous solution and the amount of strong acid sites in the NaY-P adsorbent was more than in the NaY-C adsorbent. The adsorption desulfurization results showed that the NaY-C adsorbent exhibited much higher desulfurization activity than the NaY-P adsorbent in the No.0 diesel oil, although all benzothiophene in model diesel was removed over both. In regeneration experiment, the benzothiophene removal of model diesel oil decreased from 100% to 91.97% and 85.96% after six regenerations over NaY-C and NaY-P adsorbents, respectively. Therefore, the NaY-C adsorbent possessed better desulfurization performance, possibly because the mesopore of the adsorbent is beneficial to the adsorption desulfurization.