| 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,aerogel with ? complexation adsorbent have good adsorption performance on adsorption the thiophenic sulfur compounds.The ?-complexation force is a weak chemical force,Which occurs between the transition metal ions with(n-1)d10ns0 configuration and the molecules with ? bonds.The empty s-orbitals of the transition metal ions and the ? bonds of the molecules form the usual ? bonds.At the same time,the d electrons of the metal ions can fed back to the antibonding ?-orbitals(?*)of the molecular,form the ?-? bonds.It is found that the strength of the ?-complexation is stronger than that of the van der waals forces and weaker than that of the uaual chemical force bonding,the ?-complexation could be broken by increasing temperature or reducing pressure.In this paper,Ag2O/SiO2 aerogels-like and Ag2O/SiO2-Al2O3 materials was prepared by sol-gel and ambient pressure drying.The adsorption performance of the two ?-complexation absorbents on thiophene and benzothiophene in model gasoline,the effect of benzene and cyclohexene on the adsorption performance of thiophene and benzothiophene,and the regeneration adsorption performance were investigated through static adsorption and dynamic adsorption,respectively.Meanwhile,the adsorption mechanism of absorbents on thiophene and benzothiophene and the key factors of adsorption performance were explored by XRD,XRF,BET,SEM,and XPS characterization methods.The research on desulfurization performance of Ag2O/SiO2 aerogels-like for thiophene and its derivatives shows: the Ag2O/SiO2-5 aerogels-like had the highest adsorption capacity for thiophene and benzothiophene,32.78 mgS/g and 53.84 mgS/g,respectively.After four times of regeneration using the benzene and n-heptane regeneration,the adsorption capacities of thiophene and benzothiophene were 55.43% and 58.75% of the fresh adsorbent,respectively.When the model gasoline containing 20 wt% benzene and cyclohexene(1:1),the effect on adsorption capacity of thiophene and benzothiophene was the largest,only of 35.37% and 33.75% of adsorption capacity were obtained.Owing to the strong electron density of benzene and cyclohexene,there are strong competition between thiophene and benzene or cyclohexene.The research on desulfurization performance of Ag2O/SiO2-Al2O3 for thiophene and its derivatives shows: the maximum saturation adsorption capacity of Ag2O/SiO2-Al2O3 for thiophene is higher than that of Ag2O/SiO2 aerogels-like,which is 109.29 mgS/g and 80.2 mgS/g,respectively.The results of dynamic adsorption showed that the adsorption capacities of thiophene and benzothiophene were 57.78% and 63.39% of the fresh adsorbents,respectively,after four times regeneration by benzene and n-heptane elution.The model gasoline containing 20 wt% benzene and cyclohexene(1:1)attach the largest importance to the adsorption capacity of thiophene and benzothiophene,which reduced to 40% and 34.25% of model gasoline without benzene and cyclohexene.After adding Al3+ to Ag2O/SiO2 aerogels-like,the adsorption selectivity and regeneration performance of thiophene and its derivatives on Ag2O/SiO2-Al2O3 materials were enhanced because of the ?-complexation and the acid-base interactions.The adsorption desulfurization of fuel oil provides a new adsorbent carrier material,and to explore the key factors influencing the aerogels-like type complexation adsorption of thiophene and its derivative compounds,provides a theoretical basis for the further development of the future. |
PDF Full Text Request