Comparative study on adsorptive removal of thiophenic sulfurs over Y and USY zeolites

Removal of organic sulfur compounds by using an adsorption process was carried out at ambient temperature and pressure. FAU zeolites, including NaY, HUSY cation-exchanged with metal ions such as Cu, Ni, Zn, and La, have been applied as adsorbents in the desulfurization of model and real transportation fuels. The results showed that the type of metal ion-exchanged, amount of metal ion-exchanged, and structure of zeolite have important roles in the removal of each organic sulfur. LaNaY, LaHUSY, and CuNaY possessed highest adsorption capacity toward thiophene (TH), benzothiophene (BT), and dibenzothiophene (DBT), respectively. Among the tested adsorbents, LaHUSY exhibited highest adsorption selectivity to BT and DBT in the presence of naphthalene. The comparative study indicated that La(3+) is capable of strongly adsorbing the aromatic sulfur compounds via both direct interaction at sulfur atom and via pi-electronic interaction. Adsorptive desulfurization of real diesel over LaHUSY reduced the sulfur level from 229 to less than 50 ppm, and the adsorption selectivity to 4-methyldibenzothiophene (4-MDBT) was highest.