Preparation Of Desulfurization Adsorbents For Gasoline And Investigation Of Molecular Simulation

The conditions and mechanism of Zn2+ loaded on zeolite 13X and alumina werestudied by the orthogonal test. A series of desulfurizing adsorbents were prepared withzeolite 13X, alumina and 5A molecular sieves loaded with Zn2+ and Cu2+ by themethod of impregnation at ambient termperature and desulfurizing capability of thosewere investigated in model gasoline. The desulfurizing adsorbents were prepared withalumina and 5A loaded with metallic ions by the method of wave and thedesulfurizing capability were investigated in gasoline. The topology models of MFIand MOR were built and the method of Configurational-bias Monte Carlo(CBMC)simulation was used for investigating the adsorption and distributions of ethanethiolas adsorbate in MFI and MOR type zeolites. The diffusion of ethanethiol in MFI andMOR type zeolites was studied by molecular dynamics simulation.The results show, the concentration of Zn2+ is the most important factor of theloading quantity of zeolite 13X and alumina, and the temperature secondly. The pHvalue which range from 2 to 3 effects on the loading quantity faintly. The more thequantity of loading for zeolite 13X and alumina becomes, the heavier the Zn2+concentration is at a definite scale. The loading quantity for the zeolite 13X gets to themaximal capacity at about 16000mg/L and the Langmuir model satisfactorily fits forthe zeolite 13X. But for the alumina, the loading quantity gets to the maximal capacityat about 24000mg/L and the Freundlich model fits for the alumina well. The loadingof Zn2+ seems to reach the saturation which means the metallic ions had filled theavailable sites for zeolite 13X for about 30 hours and for alumina for about 10 hours.Loading of Zn2+ from the liquid phase to the solid phase can be considered as areversible first order reaction with an equilibrium being established between the twophases.The desulfurizing capability results show that the adsorptive amount anddemercaptan rate increase with the temperature increasing for zeolite 13X, aluminaand 5A loaded with Zn2+. The adsorbate molecules need a certain energy of activationto cross the potential barrier, so the adsorbed amount is enhanced with the increase ofthe temperature. The adsorptive amount of the unbaked adsorbents loaded with Zn2+ isless than the baked obviously, but the adsorbed amount is not enhanced distinctly bythe way of increasing the baking temperature. The desulfurizing capability increasesdue to the Zn2+ impregnated. It is effective to rise the demercaptan rate by enhancingthe temperature of Model gasoline for the zeolite 13X and alumina loaded with Cu2+.For 13X and alumina loaded with Cu2+, the demercaptan rate reach about 98% after 2 III南京工业大学硕士论文 ABSTRACThours adsorption, but it will need 6 hours to reach 95% for the 5A molecular sievesloaded with Cu2+. The adsorbed amount of the unbaked adsorbents loaded with Cu2+is less than the baked. The adsorptive capacity increases due to the Cu2+ impregnated.It is disadvantageous to the desulfurizing rate in the heavier concentration modelgasoline for the desulfurizing adsorbents.Desulfurizing Adsorbents regenerated by heat at 300℃ is better than by washedwith alcohol, but SO2 was brought into being by the way of regeneration by heat.However the period is long by the way of regeneration by washing with alcohol andeffect is not well.The calculated adsorption quantity by CBMC for MFI is close agreement withthe experimental data by means of IR spectroscopy and thermogravimetry. Thecalculated results show the adsorption quantity for ethanethiol in MFI is much morethan that in MOR under coequal conditions. The observation of distribution of MFI isattributed to preferential adsorption of the ethanethiol molecules in the straight andzig-zag channels. The diffusion coefficient for MOR is bigger than that for MFI., sothe velocity of mass transfer in MOR is quicker than that in MFI.