Preparation And Performance Study Of Desulfurization Adsorbent Of Gasoline

The content of sulfur-containing compounds in the fuels oils,especially in gasoline and diesel,has been confined to a lower and lower range with the growing awareness of environmental protection and new strict regulation in recent years.Therefore,it has attracted more and more attentions on how to remove the sulfur-containing compounds deeply from the oils efficiently and effectively in order to achieve the purpose of deep desulfurization.In this paper,the desulfurization adsorbents removing sulfur-containing compounds from the fuels oils were prepared by incipient-wetness impregnation calcined reduction method and incipient wetness impregnation-sodium sulfite reduction method the latter is the first time to used to the preparation of desulfurization adsorbents.The unsupported adsorbents in which the adsorption active substance(CuCl)can react with sulfur-containing compounds were used to remove the sulfur-containing compounds from oils directly without carrier for the first time.The crystal structure,surface morphology,particle size and pore structure as well as surface area of the adsorbents were characterized by X-ray diffraction(XRD),BT-9300 HT laser particle distribution instrument,TG-DTA and BET-BJH.The concentration of sulfur-containing in the oil was analyzed by microcoulometric titration detector.The effects of preparation factor and preparation method of adsorbents on the desulfurization were investigated.The results show that the adsorbents made by incipient-wetness impregnation calcined reduction method can reach to the best adsorption capacity of ethyl mercapant 26.76 mg S/g with the adsorbents prepared at temperature of 400?,calcined time was 4 h,and the loading capacity of cuprous chloride was 9%.It can adsorb the different sulfur-containing compounds,such as thiophene,benzothiophene and dibenzothiophene.The adsorption capacity of the adsorbents was increased with the size decreasing of the organic sulfide for the smaller sulfur-containing compounds and in this case the main effect is the pore diffusion effect.On the other hand,for the organic sulfide with larger size and double bond,the adsorption capacity of the adsorbents depends mainly on the electron density(?-complexation).The results reveals that the type of carriers has much effect on the performance of adsorption,and there is great difference in the sulfur capacity between different organic sulfides.The adsorbents using cuprous chloride as active component and alumina as carrier showed favorable desulfurization performance.The adsorbents was prepared using incipient wetness impregnation-sodium sulfite reduction method with cuprous chloride as active component and alumina as carrier.The results shows that the optimum active component content was 4 %,the optimum dosage of reducing agent was 4.8% and the optimum reduction temperature 50 ?.The adsorbents made at the optomum conditions was favorable for the adsorption of different sulfur-containing compounds,especially the adsorption capacity of thiophene can reach to 42.32 mg S / g adsorbent at adsorption temperature of 40 ?.The unsupported adsorbents in which the adsorption active substance(CuCl)can react with sulfur-containing compounds were used to remove the sulfur-containing compounds from oils directly without carrier for the first time.The results show that powdery cuprous chloride has favorable adsorption for sulfur-containing compounds of organic solution,such as thiophene,benzothiophene and dibenzothiophene,respectively.The adsorption capacity of elemental sulfur can reach to 127.22 mg S/g adsorbent when the average particle size of cuprous chloride was 0.8 ?m.The adsorption capacity of sulfur in our experiment was larger than the literature value of 0.395 mmol/g(or 12.64 mg/g)obtained by Hernandez-Maldonado with Y zeolite supported cuprous chloride.In other words,the adsorption capacity of sulfur of the unsupported adsorbents is much larger than the traditional load method.It can be concluded that powdery cuprous chloride can be directly used as an deep desulfurization adsorbents(<10 ppmw).The regeneration experiment showed that the adsorbent had high activity after regeneration.A linear relationship between adsorption capacity and specific surface area was identified.The activation energy of the adsorption process was fitted by first order reaction and the activation energy was calculated.The adsorption apparent activation energy of different sulfides was 13.81 KJ mol-1(thiophene),17.69 KJ mol-1(ethanethiol),14.65 KJ mol-1(benzothiophene),and 16.04 KJ mol-1(dibenzothiophene).