Highly Selective Water Adsorption in a Lanthanum Metal–Organic Framework

Abstract

We present a new metal-organic framework (MOF) built from lanthanum and pyrazine-2,5-dicarboxylate (pyzdc) ions. This MOF, [La(pyzdc)1.5(H2O)2]⋅2 H2O, is microporous, with 1D channels that easily accommodate water molecules. Its framework is highly robust to dehydration/hydration cycles. Unusually for a MOF, it also features a high hydrothermal stability. This makes it an ideal candidate for air drying as well as for separating water/alcohol mixtures. The ability of the activated MOF to adsorb water selectively was evaluated by means of thermogravimetric analysis, powder and single-crystal X-ray diffraction and adsorption studies, indicating a maximum uptake of 1.2 mmol g(-1) MOF. These results are in agreement with the microporous structure, which permits only water molecules to enter the channels (alcohols, including methanol, are simply too large). Transient breakthrough simulations using water/methanol mixtures confirm that such mixtures can be separated cleanly using this new MOF.

Water-alcohol adsorptive separations using metal-organic frameworks and their composites as adsorbents

“…Some other synthetic strategies for designing MOFs applicable in water-alcohol adsorptive separations focus on utilizing specific interactions between MOFs and adsorbate molecules [67], micro-porous MOFs [68][69][70][71][72][73][74], and MOFs with 1D channels and molecular gates, which can only open for specific adsorbate molecules [75,76].…”

Efficient Separation of Ethanol–Methanol and Ethanol–Water Mixtures Using ZIF-8 Supported on a Hierarchical Porous Mixed-Oxide Substrate

“…Samples were measured under nitrogen. Nitrogen adsorption isotherms were measured on a Thermo Scientific Surfer instrument at 77 K. Water, methanol, and ethanol adsorption isotherms were measured on a microcalorimeter (Calvet C80, Setaram) which can operate isothermally, and it is connected to a home-built manometric apparatus at 303 K. 40 Before each adsorption measurement, samples were outgassed overnight at 473 K under vacuum (<10 –4 Torr).…”

Fabrication of a Fibrous Metal–Organic Framework and Simultaneous Immobilization of Enzymes

“… 4 Lanthanum MOFs (LaMOFs) have been synthesized by La ions coordinating to various ligands, 5 including 1,4-henylenebis (methylidyne)tetrakis, 6 5-(pyrimidyl)-tetrazolato, 7 4,4′-(hexafluoroisopropylidene) bis(benzoic acid), 8 5-carboxylato-tetrazolato, 9 and 5-amino-isophthalic acid. 10 LaMOFs can exhibit luminescence and adsorption properties 11 and have been used for selective water adsorption 10 and for the detection of picric acid and Fe 3+ ions. 12 Mono-, di-, and tricarboxylic acid-based LaMOFs were synthesized for the adsorption of arsenate from water.…”