Adsorption-Desorption Behavior and Mechanism of Dimethyl Disulfide in Hydrocarbon Liquid on Ion-Exchanged Y Zeolites

Removal of dimethyl disulfide (DMDS) from its solution has been investigated by using adsorption on the ion-exchanged Y zeolites. Effects of metal cations and preparation conditions on the removal efficiency have been accessed by performing the dynamic and static tests. The modified Y zeolites were prepared by the liquid ion-exchange method and the breakthrough adsorption capacity for DMDS was in “ Ni-Y > Co-Y > Na-Y > Ce-Y” order. The adsorbents were characterized by X-ray diffraction (XRD), thermal analysis (TGA) and X-ray photoelectron spectroscopy (XPS). Pyridine-FTIR spectroscopy showed that Lewis acidis contributed to increase the adsorption capacity, while Brønsted acid has an adverse effect on the desul-furization capability. Spectral shifts of the ν(C-S), ν(S-S) and ν(M-S) vibrations of the deactivation adsorbents were measured with the Raman spectrum. In situ Fourier transform infrared (FTIR) and temperature-programmed desorption of DMDS (DMDS-TPD) results indicated that the adsorption mechanisms on modified Y zeolite was the S-M (σ) bond which formed to increase adsorption bond energy of DMDS. The desorption activated energy, E_A, of DMDS on the modified zeolite has been obtained and was in “ Ni-Y > Co-Y > Na-Y” order.