Characteristic And Adsorption Desulfurization Performance Of Ag-Ce Bimetal Ion-exchanged Y Zeolite

The effect of twice calcination in preparation, ion exchange order, n(Ag)/n(Ce) ratio, ionexchange time and the calcination temperature on the adsorbent desulfurization were studied.The AgCeY adsorbent exchanged the Ag+first, then the Ce3+, with a Ce/Ag mole ratio of2.5for24h, as well as calcined twice at500oC exhibited the best performance. The adsorptionequilibrium for AgCeY zeolite was achieved after adsorbed at50oC for60min, the TP andBT uptake reach57%and96%respectively.The adsorbents were characterized by X-ray diffraction (XRD), the specific surface areameasurements (BET), X-ray photoelectron spectrum analysis (XPS), UV-vis diffusereflectance (UV-vis), thermal gravity analysis (TG-DTG), Pyridine adsorption infraredspectroscopy (Py-IR), Fourier transform infrared (FT-IR) and Scanning electron microscopytechniques (SEM). The adsorptive desulfurization properties of the adsorbents were evaluatedin a fixed-bed unit through different kinds of model gasolines. The gasolines tested weremade up of1-octane solution of refractory sulfur compounds of thiophene andbenzothiophene and along with a certain amount of toluene, pyridine or cyclohexene,respectively. AgCeY zeolite has a good desulfurization capacity which similar to AgY, and theadsorption affinity follow the order: benzothiophene>2,5-dimethyl thiophene>3-methylthiophene> thiophene. AgCeY adsorbent also has a high selectivity which similar to CeY, theinhibition effect on the metal ion-exchanged Y zeolites for sulfur removal was in the order ofpyridine> cyclohexene> toluene. Ag+and Ce4+on AgCeY promote each other in sulfuradsorption. The AgCeY zeolite removes organic sulfur compounds by two types of adsorptionmodes: π-complexation (through Ag+) and direct coordination (S-M) interaction (throughCe4+).The adsorption isotherm and kinetic of AgCeY were studied, and the thermodynamicparameters (ΔG, ΔH) for the adsorption of thiophene and benzothiophene were calculated.The isothermal equilibrium of the adsorption can be represented by the Langmuir model. Apseudo-first-order model can describe the kinetics of the adsorption process. The adsorptionof AgCeY is spontaneous and exothermic.