2009

Lithium-Doped 3D Covalent Organic Frameworks: High-Capacity Hydrogen Storage Materials

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D. P. Cao, J. H. Lan, W. C. Wang, and B. Smit, Lithium-Doped 3D Covalent Organic Frameworks: High-Capacity Hydrogen Storage Materials Angew Chem Int Edit 48 (26), 4730 (2009) http://dx.doi.org/10.1002/Anie.200900960

Abstract: A multiscale theoretical method predicts that the gravimetric adsorption capacities of H2 in Li-doped covalent organic frameworks based on the building blocks shown (Li violet, H white, B pink, C green, O red, Si yellow) can reach nearly 7 % at T=298 K and p=100 bar, suggesting that these Li-doped materials are promising adsorbents for hydrogen storage.

Evaluation of various water models for simulation of adsorption in hydrophobic zeolites

J. M. Castillo, D. Dubbeldam, T. J. H. Vlugt, B. Smit, and S. Calero, Evaluation of various water models for simulation of adsorption in hydrophobic zeolites Mol. Simul. 35 (12-13), 1067 (2009) http://dx.doi.org/10.1080/08927020902865923

Abstract: We have performed a molecular simulation study on water adsorption in hydrophobic zeolites. The framework structures are truly periodic and therefore the Ewald summation is the natural choice for computing the Coulombic interactions. However, a few water models have been parameterised using this method. The adsorption results are extremely sensitive to the water model used, the framework positions in the orthorhombic structure and the atomic charges of the zeolite framework. This work provides insight into the identification of the potential limitations of the available force fields and models, and into the point charges used for the zeolite atoms, when they are applied to a highly hydrophobic system. We discuss feasible routes to conciliate simulation and experimental results.

Are pressure fluctuation-based equilibrium methods really worse than nonequilibrium methods for calculating viscosities?

T. Chen, B. Smit, and A. T. Bell, Are pressure fluctuation-based equilibrium methods really worse than nonequilibrium methods for calculating viscosities? J. Chem. Phys. 131 (24), 246101 (2009) http://dx.doi.org/10.1063/1.3274802


Effect of cholesterol on the structure of a phospholipid bilayer

F. de Meyer and B. Smit, Effect of cholesterol on the structure of a phospholipid bilayer Proc Natl Acad Sci USA 106 (10), 3654 (2009) http://dx.doi.org/10.1073/pnas.0809959106

Abstract: Cholesterol plays an important role in regulating the properties of phospholipid membranes. To obtain a detailed understanding of the lipid–cholesterol interactions, we have developed a mesoscopic water–lipid–cholesterol model. In this model, we take into account the hydrophobic–hydrophilic interactions and the structure of the molecules. We compute the phase diagram of dimyristoylphosphatidylcholine–cholesterol by using dissipative particle dynamics and show that our model predicts many of the different phases that have been observed experimentally. In quantitative agreement with experimental data our model also shows the condensation effect; upon the addition of cholesterol, the area per lipid decreases more than one would expect from ideal mixing. Our calculations show that this effect is maximal close to the main-phase transition temperature, the lowest temperature for which the membrane is in the liquid phase, and is directly related to the increase of this main-phase transition temperature upon addition of cholesterol. We demonstrate that no condensation is observed if we slightly change the structure of the cholesterol molecule by adding an extra hydrophilic head group or if we decrease the size of the hydrophobic part of cholesterol.


Comment on ``Cluster Formation of Transmembrane Proteins Due to Hydrophobic Mismatching'

F. de Meyer and B. Smit, Comment on ``Cluster Formation of Transmembrane Proteins Due to Hydrophobic Mismatching'' Phys. Rev. Lett. 102 (21), 219801 (2009) http://dx.doi.org/10.1103/PhysRevLett.102.219801


Comparative Molecular Simulation Study of CO2/N2 and CH4/N2 Separation in Zeolites and Metal-Organic Frameworks

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B. Liu and B. Smit, Comparative Molecular Simulation Study of CO2/N2 and CH4/N2 Separation in Zeolites and Metal-Organic Frameworks Langmuir 25 (10), 5918 (2009) http://dx.doi.org/10.1021/la900823d

Abstract: In this work, a systematic molecular simulation study was performed to compare the separation of CO2/N2 and CH4/N2 mixtures in two different classes of nanoporous materials, zeolites, and metal−organic frameworks (MOFs). For this purpose, three zeolites (MFI, LTA, and DDR) and seven MOFs (Cu-BTC, MIL-47 (V), IRMOF-1, IRMOF-12, IRMOF-14, IRMOF-11, and IRMOF-13) were chosen as the representatives to compare. On the basis of the validated force fields, both adsorption selectivity and pure CO2 and CH4 adsorption isotherms were simulated. The results show that although MOFs perform much better for gas storage, their separation performance is comparable to zeolites; for the systems with the preferable component having a larger quadrupolar moment, both zeolites and MOFs can enhance the separation selectivity, and in contrast they both reduce the selectivity. In addition, we show that ideal adsorbed solution theory (IAST) gives a very reasonable prediction of the mixture adsorption isotherms both in zeolites and in MOFs if the pure component isotherms are known. We demonstrate that the difference in quadrupolar moment of the components is an important property that has to be considered in the selection of a membrane material.


Adsorption and Diffusion in Porous Systems

Computational Methods in Catalysis and Materials Science: An Introduction for Scientists and Engineers

K. Malek, T. J. H. Vlugt, and B. Smit, Adsorption and Diffusion in Porous Systems in Computational Methods in Catalysis and Materials Science An Introduction for Scientists and Engineers, edited by R. A. V. Santen and P. Sautet (Wiley-VCH, Weinheim, 2009), pp. 295. http://dx.doi.org/10.1002/9783527625482.ch14.


Molecular Simulation techniques using classical force fields

Computational Methods in Catalysis and Materials Science: An Introduction for Scientists and Engineers

T. J. H. Vlugt, K. Malek, and B. Smit, Molecular Simulation techniques using classical force fields in Computational Methods in Catalysis and Materials Science An Introduction for Scientists and Engineers, edited by R. A. V. Santen and P. Sautet (Wiley-VCH, Weinheim, 2009), pp. 123. http://dx.doi.org/10.1002/9783527625482.ch7.


Simulation of CO2/H-2 Mixture Separation in Metal-organic Frameworks: Effect of Catenation and Electrostatic Interactions

Q. Y. Yang, Q. Xu, B. Liu, C. L. Zhong, and B. Smit, Molecular Simulation of CO2/H-2 Mixture Separation in Metal-organic Frameworks: Effect of Catenation and Electrostatic Interactions Chin. J. Chem. Eng. 17 (5), 781 (2009) http://dx.doi.org/10.1016/S1004-9541(08)60277-3


Abstract In this work grand canonical Monte Carlo simulations were performed to study gas separation in three pairs of isoreticular metal-organic frameworks (IRMOFs) with and without catenation at room temperature. Mixture composed of CO2 and H2 was selected as the model system to separate. The results show that CO2 selectivity in catenated MOFs with multi-porous frameworks is much higher than their non-catenated counterparts. The simulations also show that the electrostatic interactions are very important for the selectivity, and the contributions of different electrostatic interactions are different, depending on pore size, pressure and mixture composition. In fact, changing the electrostatic interactions can even qualitatively change the adsorption behavior. A general conclusion is that the electrostatic interactions between adsorbate molecules and the framework atoms play a dominant role at low pressures, and these interactions in catenated MOFs have much more pronounced effects than those in their non-catenated counterparts, while the electrostatic interactions between adsorbate molecules become evident with increasing pressure, and eventually dominant.



© Berend Smit 2019