Evaluating the Selectivity of Sorbents for Noble Gas Separations across a Range of Temperatures, Loadings, and Gas Compositions

Abstract

Selectivity is the primary metric for evaluating the effectiveness of a material for the separation of gas mixtures. However, selectivities are difficult to measure experimentally, and, when measured, are typically reported as a single initial selectivity. We have calculated Xe/Kr selectivity as a function of temperature, pressure, and gas composition for HKUST‐1 and six transition metal formates using binary gas grand canonical Monte Carlo (GCMC). Our simulation results agree well with IAST predictions of selectivity from experimental data. We find that selectivity depends strongly on temperature and is best determined at the thermal conditions of the desired process. Additionally, we have shown that improvements in pore volume determination lead to significantly important differences in isotherm prediction that simulated selectivities may be improved by more realistic treatment of this parameter.

Reticular Chemistry and the Discovery of a New Family of Rare Earth (4, 8)-Connected Metal-Organic Frameworks with csq Topology Based on RE4(μ3-O)2(COO)8 Clusters

“…The IAST Xe/Kr selectivity at 298 K is among the top-performing materials (Figure c). For comparison purposes, under dilute conditions, the Xe/Kr selectivity at 298 K calculated as the ratio of the corresponding Henry coefficients (10.6 and 0.82 mmol g –1 bar –1 for Xe and Kr, respectively) is 12.9, placing Y- csq -MOF-1 in the second position on the list of the best-performing sorbents for Xe/Kr separation from nuclear reprocessing applications, including SBMOF-1 (16.2), CC3 (12.8), Co 3 (HCOO) 6 (10.7), Noria (9.4), SBMOF-2 (8.6), and HKUST-1 (8.5) , (Figure c). However, for this kind of application, the Xe uptake is also important, and compared to the leading material SBMOF-1, Y- csq -MOF-1 shows higher Xe uptake at 298 K and 1 bar (1.94 vs 1.38 mmol g –1 ), due to its higher surface area (870 vs 145 m 2 g –1 ).…”

Predicting partial atomic charges in siliceous zeolites

“…[77] The inaccessible volumes in the zeolite framework were blocked using our recently develop energy based pore mapping program with Ar as a probe (=120K, =3.4Å). [27,78] The simulated adsorption isotherms were excess corrected using the pore volumes produced by our energy based pore mapping program. Simulated heats of adsorption were obtained with fluctuation theory.…”

New Discovery of Metal–Organic Framework UTSA-280: Ultrahigh Adsorption Selectivity of Krypton over Xenon

“…At present, cryogenic distillation is mainly adopted to collect and separate Kr and Xe from UNF, but it has several disadvantages such as high energy consumption and high cost. Therefore, it is urgent to develop a more efficient and economical method to separate Kr and Xe. − Adsorption separation based on a highly selective solid adsorbent is considered to be a more economical and energy-efficient alternative to cryogenic distillation and has been widely used in separation and purification of various gas mixtures …”