Adsorption and separation of CO2 on KFI zeolites: effect of cation type and Si/Al ratio on equilibrium and kinetic properties.

Selective separation of CO2 is becoming one of the key technologies in the (petro-) chemical industry. This study focuses on the adsorption and separation of CO2 from CH4 on a new low-silica (LS) type of the eight-membered ring KFI zeolite. A series of alkali (Li, Na, K) and alkaline-earth (Mg, Ca, Sr) exchanged samples of the new LS KFI were synthesized and characterized.

Partially fluorinated MIL-47 and Al-MIL-53 frameworks: influence of functionalization on sorption and breathing properties.

Two perfluorinated metal hydroxo terephthalates [M(III)(OH)(BDC-F)]·n(guests) (M(III) = V, MIL-47-F-AS or 1-AS; Al, Al-MIL-53-F-AS or 2-AS) (BDC-F = 2-fluoro-1,4-benzenedicarboxylate; AS = as-synthesized) have been synthesized by a hydrothermal method using microwave irradiation (1-AS) or conventional electric heating (2-AS), respectively. The unreacted or occluded H(2)BDC-F molecules can be removed under vacuum by direct thermal activation or exchange of guest molecules followed by thermal treatment leading to the empty-pore forms of the title compounds [V(IV)(O)(BDC-F)] (MIL-47-F, 1) and [Al(III)(OH)(BDC-F)] (Al-MIL-53-F, 2). Thermogravimetric analysis (TGA) and temperature-dependent XRPD (TDXRPD) experiments indicate that the compounds are stable up to 385 and 480 °C, respectively.

Modeling the effect of structural changes during dynamic separation processes on MOFs.

A model able to describe the effect of structural changes in the adsorbent or adsorbed phase during the dynamic (breakthrough) separation of mixtures on metal-organic frameworks (MOFs) is presented. The methodology is exemplified for a few pertinent case studies: the separation of xylene isomers and ethylbenzene on the flexible MOF MIL-53 and the rigid MOF MIL-47. At low pressures, no preferential adsorption of any component occurs on both MOFs.

Complexity behind CO2 capture on NH2-MIL-53(Al).

Some Metal Organic Frameworks (MOFs) show excellent performance in extracting carbon dioxide from different gas mixtures. The origin of their enhanced separation ability is not clear yet. Herein, we present a combined experimental and theoretical study of the amino-functionalized MIL-53(Al) to elucidate the mechanism behind its unusual high efficiency in CO(2) capture.

A pulse chromatographic study of the adsorption properties of the amino-MIL-53 (Al) metal-organic framework.

Low-coverage adsorption properties of the metal-organic framework amino-MIL-53 (Al) were determined using the pulse chromatographic technique. By using n-alkanes, iso-alkanes, 1-alkenes, cyclohexane and benzene as probe molecules, the nature of the adsorptive interactions in amino-MIL-53 (Al) was studied. Henry adsorption constants and adsorption enthalpies of iso-alkanes are significantly lower than those of the linear alkanes, demonstrating the shape selective properties of amino-MIL-53.

An amine-functionalized MIL-53 metal-organic framework with large separation power for CO2 and CH4.

Functionalizing the well-known MIL-53(Al) metal-organic framework with amino groups increases its selectivity in CO(2)/CH(4) separations by orders of magnitude while maintaining a very high capacity for CO(2) capture.