Understanding the Potential of Zeolite Imidazolate Framework Membranes in Gas Separations Using Atomically Detailed Calculations

Abstract

Zeolite imidazolate frameworks (ZIFs) offer considerable potential for gas separation applications due to their tunable pore sizes, large surface areas, high pore volumes, and good thermal and mechanical stabilities. Although a significant number of ZIFs has been synthesized in the powder form to date, very little is currently known about the potential performance of ZIFs for membranebased gas separation applications. In this work, we used atomically detailed calculations to predict the performance of 15 different ZIF materials both in adsorption-based and membrane-based separations of CH 4 /H 2 , CO 2 /CH 4 , and CO 2 /H 2 mixtures. We predicted adsorption-based selectivity, working capacity, membrane-based selectivity, and gas permeability of ZIFs. Our results identified several ZIFs that can outperform traditional zeolite membranes and widely studied metal organic framework membranes in CH 4 /H 2 , CO 2 /CH 4 , and CO 2 / H 2 separation processes. Finally, the accuracy of the mixing theories estimating mixture adsorption and diffusion based on single component data was tested.

Methane in zeolitic imidazolate framework ZIF-90: Adsorption and diffusion by molecular dynamics and Gibbs ensemble Monte Carlo

“…This is clearly due to the fact that the contribution of the van der Waal attraction to adsorption is overestimated. This overestimation was also found in other previous papers for water and alcohol adsorption in ZIF-90 [6,11]. Hence, the well-depth was scaled by the scaling factor obtained from Pérez-Pellitero et al [23] ɛ* = 0.69ɛ, σ*= σ and Zhang et al Table T1 in supporting information).…”

“…Atci and Keskin [11] have simulated the adsorption and diffusion of various gases in ZIF-90 and other ZIFs thus evaluating the separation potential of different ZIFs. Hence, they used the rigid model for all frameworks with the UFF force field of non-bonded interactions.…”

Effect of the structural constituents of metal organic frameworks on carbon dioxide capture

“…Currently, only a few examples of MOF membranes for gas separation have been reported [208] [209]. HKUST-1 [210], Cu-(hfipbb)(H 2 hfipbb) 0.5 [206], MOF-5 [211,212], NH 2 -functionalized MIL-53(Al) and MIL-101(Al) [213][214][215][216][217][218], and many ZIF series [208,[219][220][221][222] are continuously reported as components of thin film MOF membranes. Several of these MOFs are considered to be great candidates for carbon dioxide capture in flue gas and ambient air (mainly for their CO 2 /N 2 separation properties) [207].…”

“…Although there is a lack of hard experimental data, ZIF-68, ZIF-69, ZIF-78 and ZIF-79 are all also considered to be potential CO 2 capture candidates due to their high selectivity and permeability determined by simulations [220]. found for these membranes [225].…”

“…Most of the results are based on calculations and simulations, and it is yet to be seen if experimental results will confirm these findings [220,235]. For mixed matrix membranes to become the next adsorbent materials for carbon dioxide capture, very high surface area membranes with high permeability are needed [228].…”