Studies On Desulfurization Of Thiophenic Sulfur In Model Gasolines By Adsorption Via ? Complexation With SiO₂-MO_x(M=Ni?Cu) Aerogels

With the increasingly serious environmental problems,stringent standards were made in the sulfur content of gasoline.According to the regulation of the EU countries,sulfur content in fuel oil must be less than 10?g/g since 2010.Sulfur content of fuel oil in fuel cells must be less than 0.1?g/g.Although conventional hydrodesulfurization can effectively remove the inorganic sulfur compounds,but it is difficult to remove thiophene and its derivatives.Among non-hydrodesulfurization technology,the adsorption desulfurization has better selectivity,lower operating costs,milder conditions.Therefore,comparing to other adsorption desulfurization,?complexation adsorption desulfurization with more selectivity and easier desorption regeneration has became the most promising desulfurization technology.Aerogel is a nano-porous material made of nanoscale particles.Due to its unique physical and chemical properties,aerogels with?complexation adsorbent have good adsorption performance on adsorption the thiophenic sulfur compounds.SiO₂-NiO and SiO₂-Cu O aerogels were prepared by sol-gel method and ambient pressure drying technology.The morphology and structure of SiO₂-NiO and SiO₂-Cu O aerogels were characterized by XRD?BET?XRF and SEM methods,respectively.Meanwhile,the desulfurization performance of SiO₂-NiO aerogels was studied by static adsorption and dynamic adsorption experiments.The optimum reduction conditions of SiO₂-Cu₂O aerogels with different molar ratios were obtained by exploring the reducing conditions.At the same time,the desulfurization performance of SiO₂-Cu₂O aerogels was studied by dynamic adsorption experiments.The results were conducted as follows.(1)At low temperature,the adsorption equilibrium data of thiophene on SiO₂-NiO aerogels were more in line with Temkin model;at higher temperatures,they were agree well with both Langmuir and Freundlich isotherms.(2)The maximum saturation adsorption capacity obtained by the Langmuir isotherms at different temperature decreased in the order of q_m(25?)>q_m(40?)?q_m(60?).(3)Among the three sorbents(n(Si/Ni)=6,23,74),SiO₂-NiO-23 aerogels has the maximum breakthrough adsorption capacity and is1.2308 mg S/g and 1.7779 mg S/g for thiophene or benzothiophene,respectively.(4)The optimum reduction temperature of SiO₂-Cu₂O-74 and SiO₂-Cu₂O-23 aerogels are160?,but that of SiO₂-Cu₂O-40 aerogels is only 120?.(5)The reduced SiO₂-Cu₂O aerogels had good adsorption perfoemance for thiophene and benzothiophene under the optimal reduction conditions.Among three adsorbents,SiO₂-Cu₂O-40 aerogel has the maximum breakthrough adsorption capacity and is9.0262 mg S/g?10.6673 mg S/g for thiophene or benzothiophene,respectively.The adsorption active site amount and the textural structure of aerogels could both significantly affect the adsorption performance.The higher the nickel content,specific surface area,pore volume and larger pore size of the aerogel,the larger the adsorption capacity.(6)After addition of trace benzene or cyclohexene,no change in the breakthrough adsorption capacity of SiO₂-NiO aerogels on the adsorption of thiophene was observed and has not great influence in the breakthrough adsorption capacity of SiO₂-Cu₂O aerogels on the adsorption of thiophene,but the addition of a mass of benzene or cyclohexene could lead to a clear decrease in the breakthrough adsorption capacity of thiophene or benzothiophene over SiO₂-NiO and SiO₂-Cu₂O aerogel.(7)The regeneration of the spent SiO₂-NiO was conducted by washing with n-heptane.The results showed that the breakthrough adsorption capacity of thiophene or benzothiophene was 55.56%and 76.92%of that on fresh SiO₂-NiO aerogel,respectively and the breakthrough adsorption capacity of thiophene or benzothiophene was 53.03%and 76.92%of that on fresh SiO₂-Cu₂O aerogel,respectively.