Abstract
We report a Kinetic Monte Carlo (KMC) study of the diffusion of linear n-hexane (nC6) and 2,2-dimethylbutane (22DMB) mixture in zeolite silicalite. We first investigated the loading dependences of single component self- and corrected diffusivities of nC6 at 300 K. Anisotropic transition rates are implemented to account for the distribution of the molecules within the zeolite framework. Repulsive guest-guest interactions are modeled using the parameter introduced by Reed and Ehrlich (Surf. Sci. 102:588–601, 1981). The results are in good agreement with recent experimental Quasi Elastic Neutron Scattering data of Jobic et al. (J. Phys. Chem. B 110:2195–2201, 2006), although the influence of the adsorption isotherm inflection is not reproduced. The binary diffusion study of nC6/22DMB mixtures was performed by implementing the nC6 transition rates used for the single component study while 22DMB molecules propagate via intersection-intersection hops. This KMC model allows for different saturation capacities and accounts for interactions between molecules by introducing f ij parameters. Results show the large impact of guest-guest interactions between nC6 and 22DMB on both self- and corrected diffusivities of the two components. Molecule-size effects are found to be predominant near 22DMB saturation capacity. Acceleration/deceleration effects already described in the literature are confirmed.
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Abbreviations
- a :
-
Reed–Ehrlich parameter, dimensionless
- b :
-
Reed–Ehrlich parameter, dimensionless
- b A :
-
Langmuir constant of the DSL model, Pa−1
- b B :
-
Langmuir constant of the DSL model, Pa−1
- D self :
-
self-diffusion coefficient, m2 s−1
- D C :
-
corrected diffusivity, m2 s−1
- f :
-
Reed–Ehrlich parameter, dimensionless
- k i→j :
-
transition rates from site i to site j, s−1
- k STR :
-
transition rates along straight channels, s−1
- k ZZ :
-
transition rates along zigzag channels, s−1
- K :
-
transition rates ratio, dimensionless
- n :
-
number of nearest neighbours, dimensionless
- N :
-
number of molecules, dimensionless
- Q :
-
parameter defined by (7), dimensionless
- R :
-
gas constant, J mol−1 K−1
- R(t):
-
vector position of the center of mass at a time t, m
- r i (t):
-
vector position of molecule i at a time t, m
- t :
-
time, s
- T :
-
absolute temperature, K
- ξ :
-
random number, dimensionless
- δ E :
-
variation of the activation energy, J mol−1
- θ :
-
loading or fractional occupancy, dimensionless
- Θ i :
-
number of molecules of species i, molecules per unit cell
- Θ i,sat :
-
saturation capacity of specie i, molecules per unit cell
- Δt :
-
mean residence time of a given configuration, s
- sat :
-
referring to saturation
- int :
-
referring to intersection
- str :
-
referring to straight channel
- zz :
-
referring to zigzag channel
References
Auerbach, S.M., Henson, N.J., Cheetham, A.K., Metiu, H.I.: Transport theory for cationic zeolites: diffusion of benzene in Na-Y. J. Phys. Chem. 99, 10600–10608 (1995)
Bouyermaouen, A., Bellemans, A.: Molecular simulations of the diffusion of n-butane and i-butane in silicalite. J. Chem. Phys. 108, 2170–2172 (1998)
Cavalcante, C.L.J., Ruthven, D.M.: Adsorption of branched and cyclic paraffins in silicalite. 2. Kinetics. Ind. Eng. Chem. Res. 34, 185–191 (1995)
Dubbeldam, D., Beerdsen, E., Vlugt, T.J.H., Smit, B.: Molecular simulations of loading-dependent diffusion in nanoporous materials using extended dynamically corrected transition state theory. J. Chem. Phys. 122, 224712 (2005)
Eic, M., Ruthven, D.M.: Intracrystalline diffusion of linear paraffins and benzene in silicalite studied by the ZLC methods. Stud. Surf. Sci. Catal. 49B, 897–905 (1989)
Fichthorn, K.A., Weinberg, W.H.: Theoretical foundations of dynamical Monte Carlo simulations. J. Chem. Phys. 95, 1090–1096 (1991)
Fichthorn, K.A., Weinberg, W.H.: Influence of time-dependent rates of mass transfer on the kinetics of domain growth. Phys. Rev. Lett. 68, 604–607 (1992)
Frenkel, D., Smit, B.: Understanding Molecular Simulations: From Algorithms to Applications, 2nd edn. Academic, San Diego (2002)
Gergidis, L.N., Theodorou, D.N., Jobic, H.: Dynamics of n-butane-methane mixtures in silicalite, using quasi elastic neutron scattering and molecular dynamics simulations. J. Phys. Chem. B 104, 5541–5552 (2000)
Jobic, H., Laloué, N., Laroche, C., van Baten, J.M., Krishna, R.: Influence of isotherm inflection on the loading dependence of the diffusivities of n-hexane and n-heptane in MFI zeolite. Quasi elastic neutron scattering experiments supplemented by molecular simulations. J. Phys. Chem. B 110, 2195–2201 (2006)
Jolimaître, E., Ragil, K., Tayakout-Fayolle, M., Jallut, C.: Separation of mono- and dibranched hydrocarbons on sicalite. AIChe J. 48, 1927–1937 (2002)
June, R.L., Bell, A.T., Theodorou, D.N.: Transition-state studies of xenon and SF6 diffusion in silicalite. J. Phys. Chem. 95, 8866–8878 (1991)
June, R.L., Bell, A.T., Theodorou, D.N.: Molecular dynamics studies of butane and hexane in silicalite. J. Phys. Chem. 96, 1051–1060 (1992)
Keil, F.J., Krishna, R., Coppens, M.O.: Modeling of diffusion in zeolites. Rev. Chem. Eng. 16(2), 71–197 (2000)
Koriabkina, A.O., de Jong, A.M., Hensen, E.J.M., van Santen, R.A.: Concentration and temperature dependence of the diffusivity of n-hexane in MFI-zeolites. Microporous Mesoporous Mater. 77, 119–129 (2005)
Krishna, R., Calero, S., Smit, B.: Investigation of entropy effects during sorption of mixtures of alkanes in MFI zeolite. Chem. Eng. J. 88, 81–94 (2002)
Krishna, R., Paschek, D., Baur, R.: Modeling the occupancy dependence of diffusivities in zeolites. Microporous Mesoporous Mater. 76, 233–246 (2004a)
Krishna, R., van Baten, J.M., Dubbeldam, D.: On the inflection in the concentration dependence of the Maxwell–Stefan diffusivity of CF4 in MFI zeolite. J. Phys. Chem. B 108, 14820–14822 (2004b)
Leroy, F., Rousseau, B., Fuchs, A.H.: Self-diffusion of n-alkanes in silicalite using molecular dynamics simulations: a comparison between rigid and flexible frameworks. Phys. Chem. Chem. Phys. 6, 775–783 (2004)
Maceiras, D.B., Sholl, D.S.: Analysis of binary transport diffusivities and self-diffusivities in a lattice model for silicalite. Langmuir 18, 7393–7400 (2002)
Metiu, A.I., Lu, Y.T., Zangh, Z.Y.: Epitaxial growth and the art of computer simulations. Science 255, 1088–1092 (1992)
Millot, B., Methivier, A., Jobic, H.: Adsorption of n-alkanes on silicalite crystals. A temperature-programmed desorption study. J. Phys. Chem. B 102, 3210–3215 (1998)
Paschek, D., Krishna, R.: Monte Carlo simulations of self- and transport-diffusivities of 2-methylhexane in silicalite. Phys. Chem. Chem. Phys. 2, 2389–2394 (2000)
Paschek, D., Krishna, R.: Diffusion of binary mixtures in zeolites: kinetic Monte Carlo versus molecular dynamics simulations. Langmuir 17, 247–254 (2001a)
Paschek, D., Krishna, R.: Kinetic Monte Carlo diffusion of transport diffusivities of binary mixtures in zeolites. Phys. Chem. Chem. Phys. 3, 3185–3191 (2001b)
Pascual, P., Ungerer, P., Tavitian, B., Pernot, P., Boutin, A., Development of a transferable guest-host force field for adsorption of hydrocarbons in zeolites. I. Reinvestigation of alkane adsorption in silicalite by grand canonical Monte Carlo simulation. Phys. Chem. Chem. Phys. 5, 3684–3693 (2003)
Reed, A.D., Ehrlich, G.: Surface diffusion, atomic jump rates and thermodynamics. Surf. Sci. 102, 588–601 (1981)
Runnebaum, R.C., Maginn, E.J.: Molecular dynamics simulations of alkanes in the zeolite silicalite: evidence for resonant diffusion effects. J. Phys. Chem. B 101, 6394–6408 (1997)
Saravanan, C., Auerbach, S.M: Modeling the concentration dependence of diffusion in zeolites. II. Kinetic Monte Carlo simulations of benzene in Na-Y. J. Chem. Phys. 107, 8132–8137 (1997)
Shuring, D., Jansen, A.P.J., van Santen, R.A.: Concentration and chainlenght dependence of the diffusivity of alkanes in zeolites studied with MD simulations. J. Phys. Chem. B 104, 941–948 (2000)
Skoulidas, I., Sholl, D.S.: Transport diffusivities of CH4, CF4, He, Ne, Ar, Xe and SF6 in silicalite from atomistic simulations. J. Phys. Chem. B 106, 5058–5067 (2002)
Skoulidas, A.I., Sholl, S., Krishna, R.: Correlation effects in diffusion of CH4/CF4 mixtures in MFI zeolite. A study linking MD simulations with the Maxwell–Stefan formulation. Langmuir 19, 7977–7988 (2003)
Song, L., Rees, L.V.C.: Adsorption and transport of n-hexane in silicalite-1 by the frequency response technique. J. Chem. Soc. Faraday Trans. 93, 649–657 (1997)
Smit, B., Maesen, T.L.M.: Commensurate ‘freezing’ of alkanes in the channels of a zeolite. Nature 374, 42–44 (1995)
Smit, B., Loyens, L.D.J.C., Verbist, G.L.M.M.: Simulation of adsorption and diffusion of hydrocarbons in zeolites. Faraday Discuss. 106, 93–104 (1997)
Snurr, R.Q., Kärger, J.: Molecular simulations and NMR measurements of binary diffusion in zeolites. J. Phys. Chem. B 101, 6469–6473 (1997)
Vlugt, T.J.H., Krishna, R., Smit, B.: Molecular simulations of adsorption isotherms for linear and branched alkanes and their mixtures in silicalite. J. Phys. Chem. B 103, 1102–1118 (1999)
Zhu, W., Kapteijn, F., van der Linden, B., Moulijn, J.A.: Equilibirum adsorption of linear and branched C6 alkanes on silicalite-1 studied by the tapered element oscillating microbalance. Phys. Chem. Chem. Phys. 3, 1755–1761 (2001)
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Laloué, N., Laroche, C., Jobic, H. et al. Kinetic Monte Carlo study of binary diffusion in silicalite. Adsorption 13, 491–500 (2007). https://doi.org/10.1007/s10450-007-9067-8
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DOI: https://doi.org/10.1007/s10450-007-9067-8