Enhanced Adsorption Selectivity of Hydrogen/Methane Mixtures in Metal−Organic Frameworks with Interpenetration: A Molecular Simulation Study

Abstract

In this work a systematic molecular simulation study was performed to study the effect of interpenetration on gas mixture separation in metal-organic frameworks (MOFs). To do this, three pairs of isoreticular MOFs (IRMOFs) with and without interpenetration were adopted to compare their adsorption separation selectivity for CH 4 /H 2 mixtures at room temperature. The results show that methane selectivity is greatly enhanced in the interpenetrated IRMOFs compared with their noninterpenetrated counterparts, due to the formation of additional small pores and adsorption sites by the interpenetration of frameworks. Furthermore, this work shows methane selectivity behavior is more complex in the former and selectivity differs largely in the different areas of the pores, attributed to the existence of various small pores of different sizes. In addition, the present work shows the ideal adsorbed solution theory is likely to be applicable to interpenetrated MOFs with complex structures.

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

“…Similar behavior has also been observed in our previous work for the separation of the CH 4 /H 2 mixture. 52 An explanation for the reason why pore size is an important influencing factor on selectivity may be that for CO 2 /N 2 both of the two components have quadrupolar moment; the presence of framework charges and thus electrostatic interactions between adsorbates and adsorbents increases the adsorption of both components in principle, and thus the effect of the chemistry of the materials; that is, the difference of framework atoms which have charges becomes less evident, leading to the result that pore size becomes an important factor. To corroborate this explanation, we carried out additional simulations by switching off all the electrostatic interactions involved by CO 2 and N 2 molecules (case 1) and switching off only the electrostatic interactions of CO 2 -adsorbents and N 2 -adsorbents (case 2).…”

Molecular Simulation Studies of Separation of CO2/N2, CO2/CH4, and CH4/N2 by ZIFs

“…23,40,41,46,58,59 IAST is a very efficient method for calculations of adsorption selectivities. IAST calculations were then performed in this work to check whether it is applicable for ZIFs.…”

Molecular Simulation Study of CH4/H2 Mixture Separations Using Metal Organic Framework Membranes and Composites

“…Adsorption of single component gases in MOFs has been examined in a large number of experiments and molecular simulations, [9][10][11][12][13][14][15][16][17][18][19][20] whereas less information is available about the properties of adsorbed gas mixtures in MOFs. [21][22][23][24][25][26][27][28][29] This situation is more striking when the transport of gases in MOFs is considered. A very small number of experiments 30-33 studied diffusion of adsorbed gases in MOFs since measuring gas diffusion in nanoporous materials is extremely challenging.…”