Adsorptive Removal Of Sulfur Compounds In Thiophene-n-hexane Solution

Oil is a kind of non-renewable resource.The global crude oil is getting less and less,the quality of crude oil is getting worse,and the sulfur content is getting higher and higher.Nowadays,people pay more attention to environmental protection,and the sulfur in the oil will be converted into sulfur oxides after combustion.If the sulfur oxides generated by combustion are directly discharged into the atmosphere,it will cause serious environmental pollution and affect human health.It will destroy the balance of the entire ecosystem.To reduce the pollution caused by automobile exhaust gas,the key to clean gasoline is not only to reduce the sulfur content of fuel oil,but also to keep the quality of gasoline.In the existing desulfurization technologies,the widely used hydrodesulfurization technology,although mature in technology,can effectively remove most of the sulfur-containing compounds,but at the same time it will cause octane loss,oil products decline,and high equipment costs.The adsorptive desulfurization not only has the advantages of low investment cost,low cost,convenient operation,environmental friendliness and no pollution,but also has good removal ability for sulfur compounds such as thiophene sulfur compounds,and has little loss to octane number.Therefore,adsorption desulfurization technology is currently the most promising fuel oil desulfurization technology.This paper simulates the mixture of n-hexane and thiophene used in gasoline,adopts 13 x molecular sieve,ultra-stable y-zeolite,activated carbon,attapulgite clay and clay as adsorbent.Adsorption equilibrium of each adsorbent was evaluated by static adsorption method,and it was found that each adsorbent reached equilibrium in about four hours.The kinetics and isothermal adsorption curves were plotted,and the Arrhenius Equation was used to determine the reaction as a secondary reaction.The desulfurization order of several adsorbents at equilibrium was: ultrastable Y zeolite>13X molecular sieve>activated carbon> Attapulgite clay > clay.Then,a salt solution of a metal such as nickel nitrate,iron nitrate,copper nitrate,manganese nitrate,etc.,and a nitric acid solution with a mass fraction of 2% are used to modify the above adsorbents.The results show that the desulfurization performance of all adsorbents has been improved.Among them,metal-modified 13 X molecular sieves and Y-type molecular sieves had the highest desulfurization rates of 83% and 90%.The surface area,pore size,crystal structure,morphology and surface acidity of each adsorbent before and after modification were measured by BET,XRD,SEM and TEM.The results show that the surface area and pore size of the adsorbent after the modification are reduced correspondingly,and the acidity are enhanced.Many black dot-like particles representing the metal oxide have appeared on the TEM image of the adsorbent,the dispersion is relatively uniform with the metal modified.Adsorption performance increases with adsorbent's acidity increasing.