Boosting Selective Adsorption of Xe over Kr by Double-Accessible Open-Metal Site in Metal–Organic Framework: Experimental and Theoretical Research

Abstract

Obtaining highly valuable Xe from air or other sources is highly important but still seriously restricted by its inherent inert nature and the great difficulty in separation from other inert gases, especially for Xe and Kr that show comparable size. In this work, we show both experimental and theoretical research of how to boost the selective adsorption of Xe over Kr by double-accessible open-metal site in metal–organic framework (MOF). The MOF, namely, UTSA-74, shows a high Xe uptake up to 2.7 mmol/g and a lower Kr uptake of 0.58 mmol/g at 298 K and 1 bar, leading to a high selectivity of 8.4. The effective Xe/Kr separation was further confirmed by both transient breakthrough simulation and experimental breakthrough. The separation mechanism, as unveiled by the grand canonical Monte Carlo simulation and dispersion-corrected density functional theory calculation, is due to the unique double-accessible open-metal site in UTSA-74 that affords stronger interaction toward Xe than Kr.

Thermodynamic exploration of xenon/krypton separation based on a high-throughput screening

“…Several very recent experimental reports used the strategy outlined above to improve separation properties, as well as tuning the chemical nature of the organic linkers. Tao et al 66 68 showed that a strategy of decoration of the internal pore surface with polar groups could fine-tune the separation properties in ultramicroporous MOFs: they modified the MIL-120 material by introducing hydroxyl groups, increasing the Xe/Kr selectivity.…”

Substrate‐Adatom Interface Engineering of Transition Metal Decorated Boron‐Doped Graphene Sheet for Enhanced Adsorption of Xe and Kr – A Systematic Ab initio Study

“…The filled and empty symbol represents the computational and experimental data, respectively. The selected references are, [a1], [ 8 ] [a2], [ 10 ] [a3], [ 12 ] [a4], [ 73 ] [a5], [ 72 ] [Expts., a6, a7, a8, a9] [ 7,9,74,75 ] ; [b1], [ 23 ] [b2], [ 76 ] [b3], [ 62 ] [b4], [ 44 ] [b5], [ 77 ] ; [c1], [ 27 ] [c2], [ 25 ] [c3], [ 28 ] [c4], [ 29 ] [c5], [ 30 ] [c6], [ 31 ] [c7]. [ 32 ] $ On metallic substrates, the LDA ([a1] and [a2]) calculations over predicts the in comparison with experiments [a6–a9], while the vdW corrected GGA†calculations [a3, a4, a5] reports the Xe adsorption satisfactorily.…”

“…Later, vdW corrected GGA calculations predicts the E ads of Xe/Pd(111) is −332 meV, [72] which shows very good agreement with experimental values (−360 meV) and the deviation is only 7.7%. [7,9] The similar refinement in E ads of [8] [a2], [10] [a3], [12] [a4], [73] [a5], [72] [Expts., a6, a7, a8, a9] [7,9,74,75] ; [b1], [23] [b2], [76] [b3], [62] [b4], [44] [b5], [77] ; [c1], [27] [c2], [25] [c3], [28] [c4], [29] [c5], [30] [c6], [31] [c7]. [32] Xe/Cu(111), Xe/Ag(111), Xe/Pt(111), and Xe/Ni(111) system is obtained with vdW correction.…”

Enhanced Adsorption and Separation of Xenon over Krypton via an Unsaturated Calcium Center in a Metal–Organic Framework

“…Due to their various chemical functionalities, well-defined pore size, large surface area, and high porosity, MOFs can be utilized in specific applications, especially in gas separation and catalysis processes . Currently, most studies are focusing on the separation of greenhouse gases such as CH 4 and CO 2 as well as other gases like iodine vapor capture by using MOFs in postcombustion processing. − The selective separation of noble gases such as xenon and krypton utilizing MOFs at room temperature has attracted substantial attention with the development of air purification technology. − Since some MOFs cannot offer both good thermostability and high separation ability in a Kr/Xe gas mixture due to the limitation of the structure, studies on Xe/Kr separation with these materials are both meaningful and urgent for the treatment of radioactive effluent gases from nuclear power plants. − Many papers have concentrated on the selectivity behavior of Xe and Kr, and Banerjee confirmed that SB-MOF2 has high selectivity with a Henry coefficient of 8.64 at 298 K. , Thallapally and his colleagues demonstrated that some new MOFs such as SIFSIX-3-Cu, which showed higher Xe uptake (47.5 mL/g) than active carbon, and some typical MOFs can be stable after 50 kGy β and γ irradiation. − Yan et al reported Zr-Fum MOF and compared the series with UiO-66; the Zr-Fum-Me owns a higher Xe/Kr selectivity with Henry’s constant of 14.8 and is γ irradiation resistant with a dose of 8 kGy …”