Optimized Sieving Effect for Ethanol/Water Separation by Ultramicroporous MOFs

Abstract

High‐purity ethanol is a promising renewable energy resource, however separating ethanol from trace amount of water is extremely challenging. Herein, two ultramicroporous MOFs (UTSA‐280 and Co‐squarate) were used as adsorbents. A prominent water adsorption and a negligible ethanol adsorption identify perfect sieving effect on both MOFs. Co‐squarate exhibits a surprising water adsorption capacity at low pressure that surpassing the reported MOFs. Single crystal X‐ray diffraction and theoretical calculations reveal that such prominent performance of Co‐squarate derives from the optimized sieving effect through pore structure adjustment. Co‐squarate with larger rhombohedral channel is suitable for zigzag water location, resulting in reinforced guest‐guest and guest‐framework interactions. Ultrapure ethanol (99.9 %) can be obtained directly by ethanol/water mixed vapor breaking through the columns packed with Co‐squarate, contributing to a potential for fuel‐grade ethanol purification.

Ultra‐Microporous and Stable MOFs with Zero‐Linker Ligands for Gas Capture and Separation

“…Another zero‐linker ligand, squaric acid (SqA), has been used in construction of ultra‐microporous MOFs due to its rigid and small size with diverse polydentate nature. Recently, two ultra‐microporous MOFs UTSA‐280 (Ca‐squarate) and Co‐squarate were evaluated for their exceptional ethanol/water vapor separation efficiencies that surpassing all published MOFs [20] . The squarate ligand in both MOFs adopted μ‐6 coordination model with Rs 4/3.…”

Highly Robust Metal–Organic Framework for Efficiently Catalyzing Knoevenagel Condensation and the Strecker Reaction under Solvent-Free Conditions

“…Among the solid catalysts, the employment of heterogeneous catalysts is more advantageous than the homogeneous catalysts due to having several superiorities such as (i) easier catalyst recovery by filtration from reaction mixtures , (ii) reusable for consecutive runs , and (iii) their excellent adaptability to continuous flow processes . , However, to obtain the maximum efficiency of heterogeneous catalysts, a high surface area is required for more favorable interactions between the active sites of employed insoluble solids and the substrates and reagents. In this regard, metal–organic frameworks (MOFs) are the superior candidate over other solid catalysts, as they possess distinct superior qualities such as a high surface area with well-defined porosity − and innumerable structural diversity with suitable framework tunability. − MOFs exhibit superior catalytic activity due to the presence of several active sites such as (i) open metal sites (OMSs) , (ii) structural defect formations , (iii) bared functional groups’ presence of the employed organic linkers, and so on . Moreover, the synthesis flexibility and various binding modes of the metal centers (which often generate OMSs by mild activation) made MOFs promising candidates for heterogeneous catalysis.…”

Hierarchical Mesoporous Metal–Organic Frameworks with Boric Acid Sites on the Inner Surface of Small Mesopores for the Extraction of Nucleotides in Human Plasma Samples

“…As an emerging porous material in the past two decades, metal–organic frameworks (MOFs) have attracted much attention in the field of separation science. , MOFs consist of metal clusters and organic ligands and have a large specific surface area, ordered pore structure, and tunable pore size . In particular, the structures and properties can be easily designed and manipulated. , For these reasons, MOFs are a promising matrix for adsorbents. , However, most of MOFs contain only micropores (pore size <2 nm), , which restrict the diffusion of analyte in pore channels, making most of the adsorption sites unavailable to the analyte . Relatively, hierarchical mesoporous MOFs (HM-MOFs) (pore size, 2–50 nm) can solve the problem because the mesopore in MOFs can promote the diffusion of analytes from solutions into the mesopore .…”