High-Throughput Characterization of Porous Materials Using Graphics Processing Units

Kim, Jihan; Martin, Richard L.; Rübel, Oliver; Harańczyk, Maciej; Smit, Berend

doi:10.1021/ct200787v

Cited by 61 publications

(73 citation statements)

References 43 publications

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“…For the adsorption part, we use existing computational methods based on GPUs. 12 The methodology used to compute the diffusion coefficients described in the Methods section has been implemented for this work. We have selected a set of representative experimental zeolite structures from the IZA database to test our method.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…The choice of the 15k B T cutoff was made such that energy values higher would be considered inaccessible during a typical experimental time scale. 12 The binary information (i.e., accessible/inaccessible) stored in a separate grid can be used to determine both the number of the channels and the channel direction. For example, in determining the number of channels along a given spatial direction (e.g., x direction), a twodimensional flood fill algorithm at x = 0 along the y,z plane is used to combine the adjacent accessible points together.…”

Section: ■ Methodsmentioning

confidence: 99%

“…The flood fill algorithm implemented here is similar to the one we utilized to determine blocked regions in porous materials. 12 After identfiying the distinct number of accessible regions at x = 0, each of these sections are analyzed separately in subsequent analysis. To analyze the entire channel, we compute the sum of Boltzmann weights along the y,z plane slice at a given x value for all grid points that are connected to the initial accessible region at x = 0.…”

Section: ■ Methodsmentioning

confidence: 99%

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Large-Scale Screening of Zeolite Structures for CO₂ Membrane Separations

Kim

Abouelnasr²,

Lin³

et al. 2013

J. Am. Chem. Soc.

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113

114

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ABSTRACT:We have conducted large-scale screening of zeolite materials for CO 2 /CH 4 and CO 2 /N 2 membrane separation applications using the free energy landscape of the guest molecules inside these porous materials. We show how advanced molecular simulations can be integrated with the design of a simple separation process to arrive at a metric to rank performance of over 87 000 different zeolite structures, including the known IZA zeolite structures. Our novel, efficient algorithm using graphics processing units can accurately characterize both the adsorption and diffusion properties of a given structure in just a few seconds and accordingly find a set of optimal structures for different desired purity of separated gases from a large database of porous materials in reasonable wall time. Our analysis reveals that the optimal structures for separations usually consist of channels with adsorption sites spread relatively uniformly across the entire channel such that they feature well-balanced CO 2 adsorption and diffusion properties. Our screening also shows that the top structures in the predicted zeolite database outperform the best known zeolite by a factor of 4−7. Finally, we have identified a completely different optimal set of zeolite structures that are suitable for an inverse process, in which the CO 2 is retained while CH 4 or N 2 is passed through a membrane. ■ INTRODUCTIONElevated CO 2 concentrations in the atmosphere are considered to be the primary cause of global warming. 1 Because of the ever-increasing amount of CO 2 emissions and our continuing reliance on fossil fuels, it remains imperative to search for various methods to mitigate the emission process. Among many suggested solutions, carbon capture and sequestration (CCS) is emerging as a viable technique: 2 CCS consists of utilizing materials to capture CO 2 emissions from point sources such as electric power plants, cement and steel plants, or natural gas field and injecting the adsorbed CO 2 molecules to geological reservoirs. Some of the main barriers for the large-scale implementation of CCS are the energy requirements and cost of the capture process.The currently available technology uses amines to selectively absorb CO 2 . These amines are very efficient in absorption of CO 2 , but the regeneration of the amine solution is relatively energy intensive. Alternative technologies, such as adsorption by adsorbents 3 or separations using membranes, 4 have the potential to significantly reduce the energy costs. Both technologies depend on the development of novel materials that have optimal properties for a given separation, with important classes of materials being nanoporous solids, such as zeolites and metal−organic frameworks. 3,5−8 By changing the pore topology and chemical composition, one could, in principle, synthesize millions of different materials, making it difficult to experimentally characterize and test all these materials. This gives a great opportunity for molecular simulations to identify the optimal materials in silico and gui...

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Section: ■ Results and Discussionmentioning

confidence: 99%

Section: ■ Methodsmentioning

confidence: 99%

Section: ■ Methodsmentioning

confidence: 99%

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Large-Scale Screening of Zeolite Structures for CO₂ Membrane Separations

Kim

Abouelnasr²,

Lin³

et al. 2013

J. Am. Chem. Soc.

Self Cite

113

114

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“…Cutting-edge computational tools were employed, including a DFT-based quantum-chemical implicit solvent formalism 13 for the liquid solvents and a recently developed, highly efficient sorption code 26,27 for the zeolites that employs classical force fields with well-validated parameter sets. Two specific application areas were targeted, that is, concentrating methane from a medium-concentration source to a high concentration (for example, purifying a low-quality natural gas) and concentrating a very dilute methane stream into one of the moderate concentrations (for example, enabling energy production from coal-mine ventilation air).…”

Section: Discussionmentioning

confidence: 99%

“…The Henry's constant and the pure component adsorption isotherms for CO 2 , CH 4 and N 2 gas molecules were computed using our highly efficient graphics processing unit code 26,27 , and the Ideal Adsorbed Solution Theory was then applied to estimate the mixture component uptake to reproduce the aforementioned conditions relevant to methane separations 39 . In our simulations, all interactions between gas molecules and the zeolite framework were described at the classical force field level with atomic partial charges (for Coulombic interactions) and 12-6 Lennard-Jones parameters (for van der Waals interactions) taken from Garcia-Perez et al 40 The framework was assumed to be rigid throughout the simulations, an assumption that is considered to be reasonable in zeolite structures 41 .…”

Section: Methodsmentioning

confidence: 99%

New materials for methane capture from dilute and medium-concentration sources

et al. 2013

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Methane (CH 4 ) is an important greenhouse gas, second only to CO 2 , and is emitted into the atmosphere at different concentrations from a variety of sources. However, unlike CO 2 , which has a quadrupole moment and can be captured both physically and chemically in a variety of solvents and porous solids, methane is completely non-polar and interacts very weakly with most materials. Thus, methane capture poses a challenge that can only be addressed through extensive material screening and ingenious molecular-level designs. Here we report systematic in silico studies on the methane capture effectiveness of two different materials systems, that is, liquid solvents (including ionic liquids) and nanoporous zeolites. Although none of the liquid solvents appears effective as methane sorbents, systematic screening of over 87,000 zeolite structures led to the discovery of a handful of candidates that have sufficient methane sorption capacity as well as appropriate CH 4 /CO 2 and/or CH 4 /N 2 selectivity to be technologically promising.

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