| Sulfide in fuels will produce SOx and other atmospheric pollutants after combustion,which seriously endangers the environment and human health.Simultaneously,They will poison the fuel cell stack and the electrode catalyst of the fuel processor catalyst.With the improvement of environmental regulations at home and abroad,countries have become stricter on the content of sulfides in fuel.The traditional hydrodesulfurization technology?HDS?operates under severe conditions,and it is difficult to remove macromolecular thiophene sulfides,which cannot achieve deep desulfurization.Adsorption desulfurization via?-complexation with low energy consumption,low cost,easy regeneration,environment-friendly,and can efficiently remove thiophene and its derivatives,was refered to as the most promising desulfurization technology.Adsorbent is the core of adsorption desulfurization technology.Mesoporous?complex adsorbent with many active centers and high dispersion,low preparation cost is one of the promising desulfurization adsorbents.Aerogel is a kind of three-dimensional porous network of solid materials formed by the mutual aggregate of nanoscale particles.In our previous work,we have studied a series of complex aerogel-type?-complexing adsorbents containing Ni?II?and Ag?I?,which has good desulfurization performance for removing thiophene sulfur compounds from simulated fuels because of its special physical properties.However,in the preparation process of these adsorbents active components clearly lost,and the adsoeption selectivity for thiophene and its derivatives need to be improved furture at the presence of aromatic and olefins.In this paper,the Ag2O/SiO2-TiO2-x,Ag2O/SiO2-ZrO2-y,Ag2O/SiO2-TiO2-GO?z?aerogels composite were prepared by sol-gel and normal temperature drying method in which the transition metals?Ti,Zr?were mixed into Ag2O/SiO2-50 aerogels composite.Their adsorption performance and mechanism for thiophene and its derivatives from model gasoline were investigated by equilibrium and breakthrough adsorption experiments,respectively.Moreover,the structure and physicochemical properties of aerogels composite adsorbent were investigated by XRD,BET,XRF,SEM,FTIR and NH3-TPD.The results showed that the Ag2O/SiO2-TiO2-x and Ag2O/SiO2-ZrO2-y aerogels composite doped with transition metals?Ti,Zr?had higher penetrability of thiophene,benzothiophene and dibenzothiophene than that of Ag2O/SiO2-50 aerogels composite.This is because the incorporation of transition metal ions(Ti4+,Zr4+)result in the appearance of acid centers,and also increases the increasing of?complexation centers?Ag+ content?.Among them,Ag2O/SiO2-TiO2-50 and Ag2O/SiO2-ZrO2-25 have the maximum breakthrough adsorption capacity for thiophene?benzothiophene,dibenzothiophene?,which was 11.6 mg-S/g?14.3 mg-S/g,17.7 mg-S/g?and 10.9 mg-S/g?14.3 mg-S/g,17.0 mg-S/g?respectively.In order to further improve the desulfurization performance of Ag2O/SiO2-TiO2-50.The addition of graphene oxide to Ag2O/SiO2-TiO2-GO?0.61 wt‰?increased the breakthrough capacity of thiophene?benzothiophene,dibenzothiophene?by 17%?19%,16%?compared with Ag2O/SiO2-TiO2-50.Although the specific surface area and pore diameter of the adsorbent are slightly reduced,it has a good adsorption capacity for thiophene sulfur.Addition of Ti,Zr and graphene oxide to Ag2O/SiO2-50 reduces the influence of aromatic hydrocarbons/olefins on thiophene competitive adsorption?increased adsorbent selectivity?.The adsorbent also has excellent regenerability,which was 71%,69% and 70% of fresh adsorbent after regeneration.In addition,the kinetic results showed that the adsorption kinetic data of thiophene over Ag2O/SiO2-TiO2-50,Ag2O/SiO2-ZrO2-25 and Ag2O/SiO2-TiO2-GO?0.61 wt‰?were more in line with apparent secondary adsorption kinetics model compare to apparent first-order adsorption kinetics model.The equilibrium adsorption studies showed that the equilibrium adsorption data of Ag2O/SiO2-TiO2-50,Ag2O/SiO2-ZrO2-25 and Ag2O/SiO2-TiO2-GO?0.61 wt‰?on thiophene fitted by Langmuir and Freundlich adsorption isotherm model.The thermodynamic results showed that the?G for thiophene over Ag2O/SiO2-TiO2-50,Ag2O/SiO2-ZrO2-25 and Ag2O/SiO2-TiO2-GO?0.61 wt‰?were -3.99 kJ/mol,-4.13 kJ/mol and-4.86 kJ/mol,respectively.The negative values of?G indicates that the adsorption of thiophene on the two adsorbents are spontaneous. |
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