Efficient CO2 Capture and Separation in MOFs: Effect from Isoreticular Double Interpenetration

Severe
CO2 emissions has posed an increasingly alarming
threat, motivating the development of efficient CO2 capture
materials, one of the key parts of carbon capture, utilization, and
storage (CCUS). In this study, a series of metal–organic frameworks
(MOFs) named Sc-X (X = S, M, L) were constructed inspired by recorded
MOFs, Zn-BPZ-SA and MFU-4l-Li. The corresponding isoreticular double-interpenetrating
MOFs (Sc-X-IDI) were subsequently constructed via the introduction
of isoreticular double interpenetration. Grand canonical Monte Carlo
(GCMC) simulations were adopted at 298 K and 0.1–1.0 bar to
comprehensively evaluate the CO2 capture and separation
performances in Sc-X and Sc-X-IDI, with gas distribution, isothermal
adsorption heat (Qst), and van der Waals
(vdW)/Coulomb interactions. It is showed that isoreticular double
interpenetration significantly improved the interactions between adsorbed
gases and frameworks by precisely modulating pore sizes, particularly
observed in Sc-M and Sc-M-IDI. Specifically, the Qst and Coulomb interactions exhibited a substantial increase,
rising from 28.38 and 22.19 kJ mol–1 in Sc-M to
43.52 and 38.04 kJ mol–1 in Sc-M-IDI, respectively,
at 298 K and 1.0 bar. Besides, the selectivity of CO2 over
CH4/N2 was enhanced from 55.36/107.28 in Sc-M
to 3308.61/7021.48 in Sc-M-IDI. However, the CO2 capture
capacity is significantly influenced by the pore size. Sc-M, with
a favorable pore size, exhibits the highest capture capacity of 15.86
mmol g–1 at 298 K and 1.0 bar. This study elucidated
the impact of isoreticular double interpenetration on the CO2 capture performance in MOFs.

严重二氧化碳排放的威胁日益严峻，催生了高效二氧化碳捕获材料的研究与发展，而此类材料是碳捕获、利用与储存（CCUS）过程中的关键部分。本研究受已记录的金属-有机框架（MOF）Zn-BPZ-SA和MFU-4l-Li的启发，构建了一系列名为Sc-X（X = S, M, L）的MOF。随后，通过引入等网状双重穿插结构，构建了相应的等网状双重穿插MOF（Sc-X-IDI）。在298 K和0.1–1.0 bar的条件下，采用巨正则蒙特卡洛（GCMC）模拟对Sc-X和Sc-X-IDI在二氧化碳捕获与分离性能方面进行了全面评估，评估内容包括气体分布、等温吸附热（Qst）以及范德华（vdW）/库仑相互作用。研究表明，等网状双重穿插通过精确调节孔径大小，显著增强了吸附气体与框架之间的相互作用，这在Sc-M和Sc-M-IDI中尤为明显。具体而言，在298 K和1.0 bar下，Qst和库仑相互作用分别从Sc-M的28.38和22.19 kJ mol–1增至Sc-M-IDI的43.52和38.04 kJ mol–1。此外，二氧化碳相对于甲烷/氮气的选择性从Sc-M的55.36/107.28提高至Sc-M-IDI的3308.61/7021.48。然而，二氧化碳的捕获容量受到孔径大小的显著影响。具有适宜孔径大小的Sc-M在298 K和1.0 bar条件下展现出最高的捕获容量，达到15.86 mmol g–1。本研究阐明了等网状双重穿插对MOF中二氧化碳捕获性能的影响。