In silico screening of metal–organic frameworks in separation applications

Abstract

Porous materials such as metal-organic frameworks (MOFs) and zeolitic imidazolate frameworks (ZIFs) offer considerable potential for separating a variety of mixtures such as those relevant for CO(2) capture (CO(2)/H(2), CO(2)/CH(4), CO(2)/N(2)), CH(4)/H(2), alkanes/alkenes, and hydrocarbon isomers. There are basically two different separation technologies that can be employed: (1) a pressure swing adsorption (PSA) unit with a fixed bed of adsorbent particles, and (2) a membrane device, wherein the mixture is allowed to permeate through a micro-porous crystalline layer. In view of the vast number of MOFs, and ZIFs that have been synthesized there is a need for a systematic screening of potential candidates for any given separation task. Also of importance is to investigate how MOFs and ZIFs stack up against the more traditional zeolites such as NaX and NaY with regard to their separation characteristics. This perspective highlights the potency of molecular simulations in determining the choice of the best MOF or ZIF for a given separation task. A variety of metrics that quantify the separation performance, such as adsorption selectivity, working capacity, diffusion selectivity, and membrane permeability, are determined from a combination of Configurational-Bias Monte Carlo (CBMC) and Molecular Dynamics (MD) simulations. The practical utility of the suggested screening methodology is demonstrated by comparison with available experimental data.

Microporous metal-organic framework with potential for carbon dioxide capture at ambient conditions

“…We compared the performance of our MOFs with several MOFs (Mg-MOF-74, Cu-TDPAT, CuBTC, MIL-101 and Zn(BDC)(DABCO) 0.5 ) for CO 2 capture and separation from CO 2 (1)/CH 4 (2) mixtures containing 50 mole% CO 2 , and maintained at isothermal conditions at 296 K and pressures up to 200 kPa. For comparison purposes, three zeolites (NaX 42,48 , JBW and MFI) 49 with high selectivity were also considered for analysis.…”

“…The accuracy of the IAST calculations for estimation of the component loadings for several binary mixtures in a wide variety of zeolites and MOFs has been well established by comparison with the Configurational-Biast Monte Carlo simulations of mixture adsorption 49 .…”

“…We further compared the performance of UTSA-16 with several MOFs (mmen-CuBTTri, Mg-MOF-74, MOF-177, ZIF-78, Cu-TDPAT, bioMOF-11, Zn-MOF-74) for CO 2 capture from CO 2 (1)/N 2 (2) mixtures containing 15 mole% CO 2 , and maintained at isothermal conditions at 296 K, which represent conditions relevant for flue gas processing. For comparison, five representative zeolites (NaX 42,48 , Cu-SSZ13 57 , H-SSZ13 57 , JBW 49 and MFI 49 ) exhibiting high CO 2 /N 2 separation selectivity are also included. Figure 4a presents the IAST calculations for CO 2 /N 2 adsorption selectivity.…”

Large-Scale Screening of Zeolite Structures for CO2 Membrane Separations

“…However, most diffusion coefficient calculations require expensive molecular dynamics (MD) simulations, and as such, much work in the past has focused on analyzing only 10−20 structures. 9 To avoid conducting MD simulations for thousands of structures, one can apply a geometric criterion to select those materials for which one component can enter but not the other. 16−18 This is a very efficient method to screen materials with very high diffusive selectivity, but not necessarily for high permeability.…”

Computational development of the nanoporous materials genome

“…The default study involved the screening 10 to 20 materials at a time 38 in order to tease out typical 1-dimensional structure-property relationships. As we will show in this review, only in very rare occasions the optimal material can be captured with a single volcano plot (a 1-dimensional plot of property vs activity where there is a clear peak related to a direct correlation between structural property and performance); in most cases finding the optimal material is a high-dimensional optimization problem of which the solution looks more like set of chemically disconnected volcanos.…”