Adsorption Properties of Organosulfur Compounds on Zeolite Clusters: A Density Functional Theory Calculation Study

The effects of cations of zeolite for the adsorption of organosulfur compounds were investigated by using density functional theory calculations. The binding energies of tetrahydrothiophene (C(4)H(8)S, THT), dimethyl sulfide (C(2)H(6)S, DMS), tert-butylmercaptan (C(4)H(10)S, TBM), hydrogen sulfide (H(2)S), and carbonyl sulfide (COS) on the zeolite model clusters [X(HO)(3)SiOAl(OH)(3), X = H(+), Na(+) and Ag(+)] were obtained and compared with those of H(2)O, CO(2), and C(1)-C(3) light hydrocarbons. Compared to the H(+) and Na(+) cations, the Ag(+) cation induces much stronger binding of THT, DMS, TBM, and H(2)S over H(2)O suggesting great enhancements in the adsorption selectivity. The order of binding energies of these sulfur compounds is THT > DMS > TBM > H(2)S > COS, and it does not depend on the cation types. These results agree well with the experimental adsorption uptake and selectivity properties of AgNaY zeolites for organosulfur compounds.