Molecular simulation of propane-propylene binary adsorption equilibrium in Zeolite 4A

The configurational-bias Monte Carlo (CBMC) technique in the grand-canonical (μVT) ensemble has been used to calculate the pure and binary adsorption equilibrium isotherms of propane and propylene in zeolite 4A (zeolite Na-LTA) at 298.15, 373, 423, and 473 K in the 0-500 kPa pressure range. The influence of sodium cations on the adsorption properties of zeolite 4A was investigated using the united atom (UA) force field in order to establish effective Lennard-Jones (LJ) parameters for interactions between the cations and the sp2-hybridized bond of propylene as well as the other cation-carbon interactions present in this system. A cation-free zeolite Linde type A (LTA) framework and the inclusion of sodium cations into the zeolite framework have been studied in this work. The quality of the parameters describing the carbon-sodium interactions was investigated by comparing with published experimental results for the cation-free LTA and by using other published LJ interaction parameters. Surprisingly, it was found that the sodium force field developed by Calero et al. [J. Am. Chem. Soc. 2004, 126, 11377] which is suitable for studying adsorption in other Na-contained zeolite frameworks, namely, FAU and MFI, does not work well for the Na-LTA system. It turns out that this is due to the interaction with sodium, as the simulations without cations agree very well with adsorption experiments on cation-free LTA. Our force field for zeolite 4A is in good agreement with recent experiments which show that the adsorbed amount of propane is much higher than reported previously. Good agreement of simulations with experiments was also obtained for adsorption of propane/propylene mixtures in zeolite 4A

Molecular simulation of propane-propylene binary adsorption in Zeolite 13X

In the present work, a recently developed force field for molecular simulation of the adsorption properties of linear alkanes in the sodium form of faujasite (FAU), MFI, and MOR-type zeolites is applied to reproduce experimental results of propane adsorption properties in zeolite 13X. The Lennard-Jones (LJ) parameters for interactions between the sp²-hybridized bond of propylene and the other atoms of this system are successfully determined by fitting against experimental isotherms. This new set of parameters allows the calculation of adsorption properties of propane-propylene mixtures, as well as the isosteric heat of single-component adsorption of propane and propylene in zeolite 13X. Good agreement between simulation results and experimental data for propane and propylene adsorption loadings at temperatures of 303, 323, 343, 373, 423, and 473 K and pressures in the range of 0.2-110 kPa confirms the applicability of the force field. In addition, molecular simulation will be used to guide the desorbent choice for propane/propylene separation by cyclic adsorptive processes

Study on hexane adsorption in zeolite ITQ-29 by molecular simulation

Adsorption isotherms and isosteric heat of adsorption of n-hexane in zeolite ITQ-29 were simulated using the Configurational Bias Monte Carlo (CBMC) technique in the grand-canonical (? VT) ensemble and compared with experimental results published by Gribov et al. and obtained by IR spectroscopy where the fractional loadings of n-hexane in ITQ-29 are presented in units from integral intensities of the absorption bands [u.a.]. In this work we present the simulation loadings of n-hexane in ITQ-29 converted to fractional coverages and compared to the experimental results. The simulations were performed using a united atom force field. In addition, we calculated equilibrium adsorption isotherms of ethane and propane in ITQ-29 in excellent agreement with published experiments. This force field successfully reproduces adsorption properties of linear alkanes in cation-free LTA zeolite and is suitable for fast and accurate adsorption data predictions.Process and EnergyMechanical, Maritime and Materials Engineerin