Adsorption characteristics analysis of CO2 and N2 in 13X zeolites by molecular simulation and N2 adsorption experiment
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The adsorption characteristics of CO2 and N2 in 13X zeolites have been studied by the molecular simulation and N2 adsorption experiment. It is found that the simulation results by Dreiding force fields are in an agreement with the published data. The influence of the σ and ε parameters of OZ and Na+ on the adsorption performance is discussed. Then the optimized force field parameters are obtained. Specific surface area (S B ) is calculated by simulation and experiment. Its relative error is just only 4.3 %. Therefore, it is feasible that S B of 13X zeolites is obtained by the simulation methods. Finally, the impacts of pressure and temperature on adsorption characteristics are investigated. At low pressure, CO2 adsorption in 13X zeolites belongs to the surface adsorption. As the pressure increase, the partial multilayer adsorption appears along with the surface adsorption. N2 adsorption in 13X zeolites is different from that of CO2. At low temperature of 77 K, two primary peaks are caused by the surface adsorption and multilayer adsorption respectively regardless of pressure variation. When the temperature is 273 K, the energy distribution curve appears undulate at low pressures. Then it becomes stable with the pressure increase. The surface adsorption plays an important role at the relative high pressures. The results will help to provide the theory guide for the optimization of force field parameters of adsorbents, and it is very important significance to understand the adsorption performance of zeolites.
KeywordsAdsorption characteristics 13X zeolites Molecular simulation Specific surface area Energy distribution curves
The authors gratefully acknowledge the financial support of National Natural Science Foundation of China under Grant 51306210 and Grant 51304233, of “Hong Kong Scholar Program”(XJ2013042), the Special Funds of the Basic Research Funds of the Key University in China (14CX02103A).
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