Molecular Simulation Of Adsorption Of Quinoline Derivatives On Zeolites

Fluid catalytic cracking (FCC) is one of the most important processes converting heavy oil to light oils. Vacuum gas oil(VGO) is the main feedstock of FCC. In recent years, coker gasoline(CGO) is blended in feedstock in many large oil refinery. The content of basic nitrogen compounds in CGO is3to4times that in VGO. The Y-zeolites are widely used for FCC. The high content of basic nitrogen compounds makes the Y-zeolites poisoned, which affects the product distribution of FCC and decreases the yields of gasoline and diesel oil.In this dissertation, Grand Canonical Monte Carlor simulation method has been used to investigate the adsorption properties of quinoline derivatives which include quinoline, isoquinoline,2-methylquinoline and2,4-dimethylquinoline on various zeolites.The suitable force field and reasonable precision have been selected to set up the appropriate model for the adsorption systems of quinoline derivatives on zeolites by comparing the simulated isosteric heat to the data reported in the literature.The effects of the basicity of quinoline derivatives, the aperture of zeolites, the silica alumina ratio(Si/Al) of zelites and temperature on the adsorption of quinoline derivatives on zeolites have been reviewed at573.15-873.15K under0.01-100MPa on this basis.Consistent with the order of the basicity, the order of isosteric heats is quinoline <2-methylquinoline<2,4-dimethylquinoline. The isosteric heats decrease with the increase of methl groups for the adsorption on FAU.The isosteric heats decrease with the increase of Si/Al on all of the zeolites. Quinoline adsorbes in the main channels on FAU, LTA, MFI and MOR first. There is a little quinoline adsorbing in other channels on FAU and MFI, and little quinoline adsorbing in other channels on LTA and MOR. The basicity of quinoline derivatives, temperature and Si/Al scarcely influence the active adsorption sites of quinoline derivatives on zeolites. Under lower pressures, the higher temperature, the less adsorbance of quinoline on zeolites. The influences on the adsorbance of basicity, temperature and Si/Al are consistent with the influence on the isosteric heat. Under higher pressures, the adsorbance is mostly involved with the structure of the nitrogen compounds and zeolites.The adsorption of single component, two components and three components on FAU has been simulated at773.15K under0.01-420kPa which is the industrial condition for FCC. For the single component, the isotherms can be well fitted with Langmuir equation. The adsorption capacity of quinoline, isoquinoline and2,4-dimethylquinoline on FAU is202.3lmmol·g-1,204.42mmol·g-1and134.54mmol-g"1, respectively. The correlation coefficents R2of the three quinoline derivatives are more than0.99. For the two components,2,4-dimethylquinoline is superior to both of quinoline and isoquinoline in competitive adsorption of the main channels. Quinoline shows no difference with isoquinoline about competitive adsorption. For the three components,2,4-dimethylquinoline adsorbs in the main channels when quinoline and isoquinoline distribut in other channels uniformly. The adsorbance of2,4-dimethylquinoline is obviously more than quinoline and isoquinoline when the pressure was under about60kPa. When the pressure is higher than60kPa, the adsorbance of quinoline or isoquinoline on FAU is larger than that for2,4-dimethylquinoline.The data in this dissertation can be used to guide the process of FCC with CGO, and can provide the reference for the filtration of zeolite structure and the design of new and efficient zeolites.