Molecular simulation for energy and structures of thiophene in siliceous Y and NaY

The isosteric heat of adsorption of thiophene on faujasite-type zeolites, siliceous faujasite and NaY (Si:Al=2.43) is studied by grand canonical Monte Carlo(GCMC) simulations, with different loadings of the sorbate. The simulated results are in excellent agreement with the experimental data. The contributions of short-range and long-range interactions to the heat of adsorption are discussed and the host/guest pair distribution functions (PDFs) in the MC simulations are analyzed. The analysis on the interaction energy of host/guest shows that the short-range dispersion energy dominates the adsorption of thiophene on FAU-type zeolites. A new site is revealed for thiophene and sodium ions in NaY which is different with that in siliceous Y. The sodium ions strengthen the interaction in adsorption. Electrostatic interactions and dispersion energies between sodium ions and thiophene are important factors for the heat of adsorption. The pair distribution functions of thiophene in NaY show more details of the specific sites of thiophene in NaY.