Light Hydrocarbon Adsorption Mechanisms in Two Calcium-Based Microporous Metal Organic Frameworks

Abstract

The adsorption mechanism of ethane, ethylene and acetylene (C 2 H n ; n=2, 4, 6) on two microporous metal organic frameworks (MOFs) is described here that is consistent with observations from single crystal and powder X-ray diffraction, calorimetric measurments and gas adsorption isotherm measurements. Two calcium-based MOFs, designated as SBMOF-1 and SBMOF-2 (SB: Stony Brook), form three-dimensional frameworks with one-dimensional open channels. As determined form single crystal diffraction experiments channel geometries of both SBMOF-1 and SBMOF-2 provide multiple adsorption sites for hydrocarbon molecules trough C-H … π and C-H … O interactions, similarly to interactions in the molecular and protein crystals. Both materials selectively adsorb C 2 hydrocarbon gases over methane as determined with IAST and breakthrough calculations as well as experimental breakthrough measurements, with C 2 H 6 /CH 4 selectivity as high as 74 in SBMOF-1.

Metal–organic framework with optimally selective xenon adsorption and separation

“…2a approaches two atoms per unit cell (see horizontal line), indicating commensurate Xe adsorption, which occurs when the adsorbed amount, location and orientation of an adsorbate are commensurate with the crystallographic symmetry of the adsorbent 46 . Such commensurate adsorption in SBMOF-1 was previously observed for small hydrocarbon molecules (C 2 –C 3 ) 47 48 . The observed position of Xe in the pore is consistent with calculated potential energy contours and molecular simulations of Xe adsorption ( Figs 1d and 4b , Supplementary Fig.…”

Designer Metal–Organic Frameworks for Size‐Exclusion‐Based Hydrocarbon Separations: Progress and Challenges

“…This is a result of good matching between the pore size/pore shape and the dimen- Reproduced with permission. [48] Copyright 2016, American Chemical Society.…”

One-of-a-kind: a microporous metal–organic framework capable of adsorptive separation of linear, mono- and di-branched alkane isomers via temperature- and adsorbate-dependent molecular sieving

“…In this work we demonstrate, for the first time, that the separation of monobranched and dibranched alkane isomers can be achieved by a microporous MOF, Ca(H2tcpb), through selective molecular exclusion. 21,22 More importantly, using temperature programming this compound is capable of separating a ternary mixture of linear, monobranched, and dibranched alkanes into pure components through temperature-and adsorbatedependent size sieving.…”