| With the enhanced awareness of environmental protection, countries around the world will implement more stringent restrictions on sulfur content in fuel oil in the new requirement, for the further development of low sulfur gasoline production technology is of great significance. The technology of adsorptive desulfurization is operated easily, expediently, quickly and become an important desulfurization technology. Compared to the others technology, adsorption desulfurization has several potential advantages: reduce the investment and operating cost markedly, no or quite less reduction of octane number. Key issue for the commercialization of adsorption desulfurization is developing new adsorbents with higher sulfur capacity and selectivity. The composite molecular sieves possess the pore advantage of the mesoporous material and the high selectivity of the microporous material has comprehensively applicational prospects in the fields such as petrochemical industry, adsorption, macromolecule shape selective catalysis, and so on.In this paper, the composite molecular sieve materials MCM-41-ZSM-5 were employed as adsorbents for adsorption desulfurization on model gasoline,the better result was obtained.A series of micro-mesoporous composite molecular sieves were synthesized by the assembly behaviors of alkali-treated ZSM-5 zeolite, and characterized by XRD, BET techniques. Adsorption properties for sulfur removal from model gasoline on the composite molecular sieves were studied. The results indicate the composite materials with microporous and mesoporous double pores-size distribution possess ordered hexagonal structure of MCM-41-type and high surface areas. The factors were studied one by one, got the optimum synthesis condition. Analysis of orthogonal experiments gives the orders of the importance of each factor in the synthesis of composite materials: pH value is the most important; it is more important to control the pH value than the concentration of NaOH; less important influential factors are crystallization time and time of alkali-treatment.The composite molecular sieve material as the support, two kinds of adsorbents were prepared using impregnation method: Fe/MCM-41-ZSM-5 and Ni-Co/MCM-41-ZSM-5. Active components within the adsorbents were Fe2O3, and Co3O4,NiO respectively. The effects of preparation and adsorption conditions on performance of the adsorbents were investigated and the suitable conditions were determined.The suitable preparation conditions of Fe/MCM-41-ZSM-5 are iron nitrate concentration 0.20 mol/L, impregnation time 10h, drying temperature 100℃, calcinating 550℃for 4h. The suitable adsorption conditions are: ambient temperature and pressure, the adsorbent-oil ratio 1:60, adsorption time 1h. The saturated adsorption quality is 36.46mgS/g adsorbent. The suitable preparation conditions of Ni-Co/MCM-41-ZSM-5 are : nickel and cobalt loaded quality 10%, impregnation time 12h, drying temperature 100℃, calcinating 450℃for 4h. The suitable adsorption conditions are the same as the first adsorbent. The saturated adsorption quality is 36.84 mgS/g adsorbent.Aromatic hydrocarbon compound have strong competence with sulfide. Therefore, it is necessary that how to enhance selectivity of sorbent, when use the real gasoline, the sulfur capacities of the adsorbents are 10.21,10.5mgS/g adsorbent respectively. Reviewed by dynamic adsorption experiments, the sulfur capacities are 8.6 and 9.6 mg S/g.π-complexation will be the mainly mechanism of the adsorption.
|
PDF Full Text Request