Study on the adsorption behavior and mechanism of dimethyl sulfide on silver modified bentonite by in situ FTIR and temperature-programmed desorption

Abstract

A high-performance adsorbent was developed by loading silver on bentonite for the adsorption of dimethyl sulfide (DMS) from liquid hydrocarbon streams under ambient conditions. It demonstrated a high saturated sulfur capacity of 80mg S/g adsorbent when the bentonite was loaded with 8wt% Ag+ and calcined at 150°C. The prepared adsorbents were characterized by adsorption of nitrogen (BET), Transmission Electron Microscopy (TEM), X-ray diffraction (XRD), pyridine Fourier transform infrared spectroscopy (pyridine-FTIR) and Thermogravimetric Analysis (TG). The results showed that the silver species dispersed on the surface of bentonite had an important role in determining the DMS removal performance while the surface acid sites of adsorbent had little correlation with the DMS removal performance. Combined techniques of temperature programmed desorption of DMS (DMS-TPD) and in situ Fourier transform infrared spectroscopy (in situ FTIR) were used to investigate the adsorption mechanism of DMS on raw bentonite and Ag+ modified bentonite, respectively. The results revealed that three interaction patterns were existed between the adsorbed DMS and raw bentonite while two interaction patterns were observed between adsorbed DMS and Ag+ modified bentonite. The DMS molecules hardly entered into the interlayer of Ag+ modified bentonite due to the strong interactions between DMS molecules and silver cations.