Molecular Dynamics Simulation of Straight-chain Alkanes Adsorption and Diffusion in Zeolite


Department of Chemical Engineering, University of Tehran, Tehran, Iran


Molecular dynamics simulations were applied to calculate self-diffusion coefficients (Di,self) and heats of  adsorption for ethane, propane and n-butane. Simulations were done in temperature range of 300-525 K for various concentrations inside the pores of silicalite type zeolite.  Calculated values of selfdiffusion coefficients and heats of adsorption resulted from the current work, were in better agreement with experimental estimated values found in literature than those resulted from simulations reported by other authors. For instance, at temperature of 300K and loading of 5 molecules/unit cell, self-diffusion coefficients of 16.56×10-5, 7.62×10-5 and 5.81×10-5 cm2/s were calculated for C2H6, C3H8, n-C4H10 respectively  was compared to experimental reported values of 10×10-5, 9×10-5 and 6×10-5 cm2/s. At the same conditions, adsorption energies of 9.2, 11.48, and 13.66 kcal/mol.  were calculated for ethane,propane, and n-butane respectively, while the experimental reported values found to be6.93, 9.7 and12.7 kcal/mol.  Simulations showed that the  diffusion decreases when loading increases and the heatsof adsorptions were increase by molecular weight of hydrocarbons for all adsorbates studied. 


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