| In recent years,with the large-scale use of fuel oil,there have been serious environmental pollution problems,so the desulfurization technology of fuel oil is significant.Although hydrodesulfurization can effectively remove inorganic sulfides from gasoline,it is difficult to remove thiophene and its derivatives.the adsorption desulfurization based on?complexation is a desulfurization technology with high selectivity,low cost,easy regeneration,mild conditions and good desulfurization effect on thiophene and its derivatives.The core of adsorption desulfurization technology is adsorbent.At present,the development of a desulfurization adsorbent mainly based on mesopores,with a large specific surface area,a large number of adsorptive active centers,a high dispersion degree,and a low preparation cost is the main research direction.Aerogel is a kind of nanoporous material with continuous network structure formed by nano-colloidal particles agglomerated.Due to its unique physical and chemical properties,aerogel with?complexation adsorbent have good adsorption performance on the thiophenic sulfur compounds.In this paper,Ag2O/SiO2-Al2O3 composite aerogels-like adsorbents with different n?Si/Al?and Ag2O/SiO2-Al2O3-GO composite aerogels-like adsorbents with different graphene oxide content were prepared by sol-gel and ambient pressure drying.The adsorption and adsorption mechanisms of thiophene and its derivatives were investigated through static adsorption and dynamic adsorption.Meanwhile,key factors affecting adsorbent performance of the adsorbent were studied by BET,XRD,XRF,SEM,TEM and XPS characterization methods.The research on desulfurization performance of Ag2O/SiO2-Al2O3 composite aerogels-like adsorbents with different n?Si/Al?for thiophene and its derivatives is higher than that of Ag2O/SiO2-50 composite aerogels-like.When the molar ratio of Si/Al was 100,the penetration capacity was the highest,and its adsorption capacity for thiophene and benzothiophene was 13.676 mgS/g and 17.78 mgS/g.The adsorption capacity for thiophene on Ag2O/SiO2-Al2O3-GO composite aerogels-like with different contents of graphene oxide is higher than that of Ag2O/SiO2-Al2O3-100composite aerogels-like adsorbents.Ag2O/SiO2-Al2O3-GO?1.14 wt‰?composite aerogels-like adsorbents have the best desulfurization performance.Its adsorption capacities for thiophene and benzothiophene were 16.41 mgS/g and 21.88 mgS/g,respectively.After four times of regeneration using the benzene and n-heptane regeneration,Ag2O/SiO2-Al2O3-100 and Ag2O/SiO2-Al2O3-GO?1.14 wt‰?composite aerogels-like adsorbents capacities of thiophene were 76.9%and 50%of the fresh adsorbent,respectively.Benzene and graphene oxide have a?-?interaction after addition of graphene oxide,,so benzene is more difficult to be eluted and occupy more adsorptive activity centers during the regeneration process,and ultimately leads to poor regeneration performance.When cyclohexene and toluene are present,it will affect the adsorption of thiophene on Ag2O/SiO2-Al2O3-100 and Ag2O/SiO2-Al2O3-GO?1.14wt‰?composite aerogels-like adsorbents.When 10 wt%toluene and 10 wt%cyclohexene are present,the adsorption of thiophene had the greatest effect,which decreased to 20%and 8.01%,respectively.Kinetic studies indicated that the kinetic adsorption data of thiophene on Ag2O/SiO2-Al2O3-100 and Ag2O/SiO2-Al2O3-GO?1.14wt‰?composite aerogels-like adsorbents are more consistent with the pseudo-second-order kinetic model.Its speed control steps related to surface reactions.Equilibrium adsorption studies indicated that the equilibrium adsorption data of thiophene on Ag2O/SiO2-Al2O3-100 and Ag2O/SiO2-Al2O3-GO?1.14wt‰?composite aerogels-like adsorbents conforms to Langmuir and Freundlich adsorption isotherms.The saturated adsorption capacity at the temperature?298 K?is lower than the saturated adsorption capacity at the temperature?333 K?.Thermodynamic studies indicated that the?H and?S in the adsorption of thiophene on Ag2O/SiO2-Al2O3-100composite aerogels-like adsorbents are 6.123 kJ/mol and 42.435 J/mol?K.The?H and?S of Ag2O/SiO2-Al2O3-GO?1.14 wt‰?composite aerogels-like were 1.680 kJ/mol and 29.137 J/mol?K,respectively.?H is positive,indicating that the adsorption process is endothermic and the?S value is positive,indicating that the degree of contamination in the adsorption process increases.at the temperature?298 K?,the?G in the adsorption of thiophene on Ag2O/SiO2-Al2O3-100 and Ag2O/SiO2-Al2O3-GO?1.14 wt‰?composite aerogels-like adsorbents were-6.50 kJ/mol and-7.00kJ/mol,respectively.The adsorption process occurs spontaneously. |
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