Describing binary mixture diffusion in carbon nanotubes with the Maxwell-Stefan equations. An investigation using molecular dynamics simulations

被引:63
作者
Krishna, R [1 ]
van Baten, JM [1 ]
机构
[1] Univ Amsterdam, Vant Hoff Inst Mol Sci, NL-1018 WV Amsterdam, Netherlands
关键词
D O I
10.1021/ie051126d
中图分类号
TQ [化学工业];
学科分类号
0817 ;
摘要
Adsorption and diffusion of pure components and binary mixtures containing methane, ethane, propane, n-butane, isobutane, and hydrogen at 300 K in a variety of configurations of carbon nanotubes (CNTs) have been investigated using configurational-bias Monte Carlo (CBMC) simulations and molecular dynamics (MD) simulations. Both self-diffusivities, D-i,D-self, and the Maxwell-Stefan (MS) diffusivities, D-i, were determined for a variety of molecular loadings Theta, approaching saturation limits. For comparison purposes, self-diffusivities were also determined in pure fluids of varying densities using MD. At low loadings Theta, the D-i,D-self correspond to the value for low-density gases. With increasing loadings, however, the D-i,D-self in CNTs are slightly higher than the values in fluids when compared at the same molecular density. In CNTs, the D-i,D-self is significantly smaller in magnitude than the MS diffusivity D-i, signifying strong correlations between molecular jumps along the tube. Consequently, for mixture diffusion, the component self-diffusivities are close to-ether. MD simulations of binary-mixture diffusion demonstrate that the mixture-diffusion characteristics can be estimated with good accuracy from the pure-component diffusion parameters using the MS diffusion formulation. In the estimation procedure, the binary-exchange parameter D-12 is estimated from the pure-component self-exchange coefficients D-11 and D-22 using the interpolation scheme Suggested earlier for transport in zeolites.
引用
收藏
页码:2084 / 2093
页数:10
相关论文
共 64 条
[1]   Diffusivities of Ar and Ne in carbon nanotubes [J].
Ackerman, DM ;
Skoulidas, AI ;
Sholl, DS ;
Johnson, JK .
MOLECULAR SIMULATION, 2003, 29 (10-11) :677-684
[2]   Molecular selectivity due to adsorption properties in nanotubes [J].
Arab, M ;
Picaud, F ;
Devel, M ;
Ramseyer, C ;
Girardet, C .
PHYSICAL REVIEW B, 2004, 69 (16) :165401-1
[3]   Air separation by single wall carbon nanotubes: Thermodynamics and adsorptive selectivity [J].
Arora, G ;
Sandler, SI .
JOURNAL OF CHEMICAL PHYSICS, 2005, 123 (04)
[4]   Adsorption and diffusion of molecular nitrogen in single wall carbon nanotubes [J].
Arora, G ;
Wagner, NJ ;
Sandler, SI .
LANGMUIR, 2004, 20 (15) :6268-6277
[5]   Comparisons of diffusive and viscous contributions to transport coefficients of light gases in single-walled carbon nanotubes [J].
Bhatia, SK ;
Chen, HB ;
Sholl, DS .
MOLECULAR SIMULATION, 2005, 31 (09) :643-649
[6]   PATH-INTEGRAL SIMULATIONS OF MIXED PARA-D-2 AND ORTHO-D-2 CLUSTERS - THE ORIENTATIONAL EFFECTS [J].
BUCH, V .
JOURNAL OF CHEMICAL PHYSICS, 1994, 100 (10) :7610-7629
[7]   Understanding the role of sodium during adsorption: A force field for alkanes in sodium-exchanged faujasites [J].
Calero, S ;
Dubbeldam, D ;
Krishna, R ;
Smit, B ;
Vlugt, TJH ;
Denayer, JFM ;
Martens, JA ;
Maesen, TLM .
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 2004, 126 (36) :11377-11386
[8]   Adsorption and separation of hydrogen isotopes in carbon nanotubes: Multicomponent grand canonical Monte Carlo simulations [J].
Challa, SR ;
Sholl, DS ;
Johnson, JK .
JOURNAL OF CHEMICAL PHYSICS, 2002, 116 (02) :814-824
[9]   Nonequilibrium molecular dynamics simulations of diffusion of binary mixtures containing short n-alkanes in faujasite [J].
Chempath, S ;
Krishna, R ;
Snurr, RQ .
JOURNAL OF PHYSICAL CHEMISTRY B, 2004, 108 (35) :13481-13491
[10]   Transport diffusion of gases is rapid in flexible carbon nanotubes [J].
Chen, HB ;
Johnson, JK ;
Sholl, DS .
JOURNAL OF PHYSICAL CHEMISTRY B, 2006, 110 (05) :1971-1975