Preparation And Adsorption Desulfurization Performance Of AgCeY Zeolites Of Different Si/Al Ratio

AgCeY-n adsorbents was successfully prepared by the liquid-phase ion-exchange NaY-n with different Si/Al ratios n(n=3.0, 4.8, 5.3) zeolites. The adsorbents were characterized by X-ray diffraction(XRD), the specific surface area measurements(BET), X-ray photoelectron spectroscopy(XPS), Pyridine adsorption infrared spectroscopy(Py-IR), Fourier transform infrared(FT-IR), Scanning electron microscopy techniques(SEM). The adsorptive desulfurization properties of the adsorbents were studied in bath and fixed-bed unit through a model gasoline which made up of 1-octane solution of the refractory sulfur compounds(Such as thiophene and benzothiophene) and a certain amount of toluene or cyclohexene. The results showed that(1) AgCeY-5.3 exhibited the best sulfur removal capacity and selectivity. The TP and BT removal of AgCeY-5.3 with model oil, which obtain toluene, were 76.5% and 99.9%.The capacity for sulfur removal onto AgCeY-n decreased in the order AgCeY-5.3 >AgCe Y-4.8 > AgCe Y-3.0 for a model oil comprising thiophene(TP) and benzothiophene(BT),along with certain amounts of toluene or cyclohexene.(2) For each sorbent, the selectivity of adsorption of sulfur compounds from liquid solutions followed the order: benzothiophene >thiophene. The effect on the metal ion-exchanged Y zeolites for sulfur removal in the order:cyclohexene > toluene.(3) With the increasing of Si/Al ratio, more surface metal loadings,more Lewis acid sites and less Br?nsted acid sites.NaY zeolite(which Si/Al ratio was 5.3) was prepared by liquid-phase ion-exchange method, hydrothermal ion exchange method and microwave-assisted liquid ion exchange method. The adsorption isotherm and kinetic of AgCe Y were studied, and the thermodynamic parameters(ΔG, ΔH) for the adsorption of thiophene and benzothiophene were calculated.The results showed that:(1) The TP and BT removal of AgCeY which prepared by microwave-assisted liquid ion exchange method with model oil, which obtain toluene, were84.8% and 99.9%. The desulfurization effect of microwave-assisted liquid ion exchange method is better than hydrothermal ion exchange method and microwave-assisted liquid ion exchange method.(2) The adsorption of desulfurization activity of the AgCeY adsorbent with liquid-phase ion exchange method taking advantage of microwaves irradiation, microwave power of 240 W, microwave irradiation time of 20 min as well as Microwave heating temperature of 70 ℃ was found to be optimal. The adsorption of AgCeY is spontaneous andexothermic.(3) The kinetics for the adsorption process can be described by either the Langmuir model or a pseudo-second-order model. ΔH for the adsorption of TP and BT were<0. The adsorption is spontaneous and exothermic.