Molecular Traffic Control in a Nanoscale System

Clark, Louis A.; Ye, George T.; Snurr, Randall Q.

doi:10.1103/physrevlett.84.2893

Cited by 135 publications

(141 citation statements)

References 15 publications

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“…32 We note that MPC is different from molecular traffic control, 33 which is caused by mutual correlations in the movement of a multicomponent fluid through two types of pores. As a specific MPC example, we study the mechanism behind tunable anisotropy of ethane in ERI-type zeolite membranes.…”

Section: Introductionmentioning

confidence: 94%

Dynamically Corrected Transition State Theory Calculations of Self-Diffusion in Anisotropic Nanoporous Materials

et al. 2006

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We apply the dynamically corrected transition state theory to confinements with complex structures. This method is able to compute self-diffusion coefficients for adsorbate-adsorbent systems far beyond the time scales accessible to molecular dynamics. Two example cage/window-type confinements are examined: ethane in ERI-and CHA-type zeolites. In ERI-type zeolites, each hop in the z direction is preceded by a hop in xy direction and diffusion is anisotropic. The lattice for CHA-type zeolite is a rhombohedral Bravais lattice, and diffusion can be considered isotropic in practice. The anisotropic behavior of ERI-type cages reverses with loading, i.e., at low loading the diffusion in the z direction is two times faster than in the xy direction, while for higher loadings this changes to a z diffusivity that is more than two times slower. At low loading the diffusion is impeded by the eight-ring windows, i.e., the exits out of the cage to the next, but at higher loadings the barrier is formed by the center of the cages.

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Section: Introductionmentioning

confidence: 94%

Dynamically Corrected Transition State Theory Calculations of Self-Diffusion in Anisotropic Nanoporous Materials

et al. 2006

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“…The latter could be used to control whether the structure is effectively a one-dimensional channel or a three-dimensional intersecting channel system for a certain guest molecule. This opens up the possibility of "molecular traffic control", 11,12 where species in a mixture diffuse preferentially along different channel directions based on size or chemical nature. Because the positions of guest molecules are easily obtained from molecular simulation, simulation can play an important role in understanding siting in MOFs, how this affects adsorption properties, and ultimately how MOFs can be designed for particular applications.…”

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confidence: 99%

Separation and Molecular-Level Segregation of Complex Alkane Mixtures in Metal−Organic Frameworks

et al. 2008

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Metal-organic frameworks (MOFs) are a new class of nanoporous materials that have good stability, high void volumes, and welldefined tailorable cavities of uniform size.1 MOFs consist of metal oxide vertices interconnected by rigid or semirigid organic molecules having terminal functional groups that bind to the metal corners. The pores of MOFs can be systematically varied by a judicious choice of linker molecules and/or metal corners. Moreover, the higher void volumes in comparison to, for example, zeolites could potentially lead to very efficient separation processes. In this paper, we show that MOFs are highly selective for separating alkanes based on the degree of branching in complex, multicomponent mixtures. This is potentially useful for removing low research octane number (RON) alkanes from a mixed alkane stream. In addition, we report an unusual molecular-level segregation of molecules based on their degree of branching.The separation of alkane mixtures using nanoporous materials is up to date usually achieved by selective adsorption within zeolitic materials. Calero et al. 2 and Krishna et al. 3 showed using simulations that linear, monomethyl, and dimethyl alkanes in the 5-7 carbon atom range can be separated using silicalite-1 (MFItopology) by exploiting configurational entropy effects. There are only a few papers on separation of alkanes in MOFs. Düren and Snurr simulated methane/n-butane mixtures in a family of related MOFs and found that selectivity for n-butane varied strongly with the MOF linker molecule. 4 Several groups simulated mixtures of branched and linear alkanes in IRMOFs but did not observe significant selectivities for these structures. 5 Experimentally, Chen et al. demonstrated that linear alkanes can enter the pores of MOF-508, but branched alkanes cannot.6 Interestingly, recently Barcia et al. found experimentally that hexane could be kinetically separated from 3-methylpentane and 2,2-dimethylbutane by fixed bed adsorption using a Zn 2 (1,4-bdc) 2 (dabco)] MOF, 7 where "bdc" denotes 1,4-benzenedicarboxylate and "dabco" denotes 1,4-diazabicyclo[2.2.2]-octane. In this work we refer to this structure, synthesized by Dybtsev et al., 8 as MOF-1. Figure 1 shows a cartoon of the structure. For the adsorbates in this study, the structure is essentially a one-dimensional channel system. MOF-1 is thermally stable and easily reactivated and reused. To investigate the use of MOF-1 as an adsorbent for alkane separations relevant to industrial processes, we simulated a multicomponent mixture in the C 5 -C 7 range using grand canonical Monte Carlo (GCMC). Details are given in the Supporting Information. We note that the simulations are performed using a rigid framework, although flexibility for MOFs might be more important than in zeolites. However, for alkanes we expect the differences to be small. Figure 2 shows the absolute adsorption isotherms predicted for a 13-component alkane mixture in MOF-1. The numbers at the right side of the figure are the research octane numbers. The figure shows ...

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“…100 MeV proton beams are obtained by increasing the intensities to 2 Â 10 20 W=cm 2 . Multi-MeV ion acceleration from laser-irradiated solid foils has become a highly active field of research over the past few years [1][2][3][4][5][6]. The wide potential applications [7] include tumor therapy, radiography, and laser-driven fusion.…”

mentioning

confidence: 99%

“…Most applications require a high-energy ion beam with large particle number and monoenergetic spectrum. Radiation-pressure acceleration (RPA) [3][4][5][6] using circularly polarized (CP) laser pulses has emerged as a promising route to obtaining such high-quality ion beams in a much more efficient manner, compared to the target normal sheath acceleration (TNSA) [1,2].…”

mentioning

confidence: 99%

Radiation-Pressure Acceleration of Ion Beams from Nanofoil Targets: The Leaky Light-Sail Regime

et al. 2010

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Molecular Traffic Control in a Nanoscale System

Cited by 135 publications

References 15 publications

Dynamically Corrected Transition State Theory Calculations of Self-Diffusion in Anisotropic Nanoporous Materials

Dynamically Corrected Transition State Theory Calculations of Self-Diffusion in Anisotropic Nanoporous Materials

Separation and Molecular-Level Segregation of Complex Alkane Mixtures in Metal−Organic Frameworks

Radiation-Pressure Acceleration of Ion Beams from Nanofoil Targets: The Leaky Light-Sail Regime

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