Robust Ultramicroporous Metal–Organic Framework with Rich Hydroxyl-Decorated Channel Walls for Highly Selective Noble Gas Separation

Abstract

Separation of a gas mixture achieved by the vacuum swing adsorption (VSA) technology is considered as an efficient and energy-saving method for Xe/Kr mixtures, but developing efficient and stable adsorbents remains challenging. Herein, we report an ultramicroporous metal–organic framework, namely, MIL-120 with a suitable pore size (5.4 Å × 4.7 Å), rich hydroxyl-decorated sites, and ultrahigh stability, which is capable of highly selective adsorption of xenon from krypton. Specifically, MIL-120 exhibits an excellent adsorption capacity of Xe up to 1.15 and 1.99 mmol g–1 at 298 K under 0.1 bar and 1 bar, respectively, and outstanding ideal adsorbed solution theory selectivity of 9.6 for the Xe/Kr mixture, which is comparable to those of benchmark porous materials. The isosteric heat of adsorption (Q st) and density functional theory calculations further confirm the stronger interaction of the adsorbent toward Xe than Kr. Furthermore, the cycling breakthrough experiments, hydrothermal and acid-based stability tests, and VSA assessment comprehensively demonstrate that the MIL-120 is an efficient and potent adsorbent for Xe/Kr separation under industrial conditions.

Thermodynamic−Kinetic Synergistic Separation of CH4/N2 on A Robust Aluminum-Based Metal−Organic Framework

“…These values were slightly higher than those previously reported, which may be attributed to the sample washing step using high temperature methanol. 44 The pore size distribution was evaluated using the Horvath-Kawazoe model (Figure 2b) and the calculated pore size (4.8 Å) was consistent with the results obtained from the crystal structure (5.4 × 4.7 Å). 40 From a practical point of view, the pH value of the initial solution and thermal stability are two key metrics for evaluating the adsorbent.…”

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.…”

Al-MOF-derived spindle-like hierarchical porous activated carbon for advanced supercapacitors

“…S1 † that MIL-120 and MIL-118 have been successfully synthesized. 24,25 Fig. S2 † shows that both the as-prepared samples have a rodlike morphology, however, the size of MIL-118 is much Fig.…”

“…The observed characteristic peaks of Al-BTEC at 9°, 13°a nd 20°and the peaks at 9°, 18°, 25°, 43°and 44°are corresponding to the characteristic peaks of MIL-120 and MIL-118, respectively, indicating that the obtained Al-BTEC is a mixture of two MOF structures. 24,25 The characteristic peak at 25°of Al@C is assigned to the (220) crystal plane of γ-Al 2 O 3 . It can also be seen that the characteristic peaks of Al 2 O 3 disappear after treatment with a NaOH solution, and only the peaks of porous carbon remain in SPC.…”