Superhydrophobic zeolitic imidazolate framework with suitable SOD cage for effective CH₄/N₂ adsorptive separation in humid environments

Abstract

Various adsorbents for CH 4 /N 2 separation were developed to enrich low-concentration coal-mine methane. Most are hydrophilic and cannot treat moist coal-mine methane.We report for the first time a microporous zeolitic imidazolate framework Co(dcIm) 2 (TUT-100) with superhydrophobic properties for CH 4 /N 2 separation. The CH 4 adsorption capacity and CH 4 /N 2 selectivity were as high as 45.29 cm 3 /cm 3 and 6.3 (298 K, 1 bar), respectively, which results from the suitable SOD cage size (0.80 nm). The H 2 O adsorption was lower than 6.3 cm 3 /g at 298 K and near saturated pressure due to the hydrophobic group Cl. Breakthrough experiments were carried out to indicate the significant potential for CH 4 /N 2 adsorption separation in a humid environment. The adsorption behavior of the gas mixture on the TUT-100 was investigated by the Grand Canonical Monte Carlo method and coupled with the experimental data.

Thermodynamic‐kinetic synergistic separation of CH4/N2 on a robust aluminum‐based metal‐organic framework

“…In addition, as revealed using multiple breakthrough experiments, the separation time of MIL‐120Al can be maintained after 10 cycles, implying its good reusability (Figure 6E). From a practical viewpoint, the effect of H 2 O in the enrichment process of low‐concentration CMM should also be considered, 60 thus, breakthrough experiments were performed using the CH 4 /N 2 (50/50) mixture with humidity in the range of 22%–81% RH. Figure 6F shows the retention time of N 2 and CH 4 were similar to those observed in a dry environment even under 81% RH, indicating that the separation performance of this material was not significantly affected by the presence of H 2 O.…”

“…In addition, as revealed using multiple breakthrough experiments, the separation time of MIL-120Al can be maintained after 10 cycles, implying its good reusability (Figure 6E). From a practical viewpoint, the effect of H 2 O in the enrichment process of low-concentration CMM should also be considered, 60…”

CH4/N2Adsorptive Separation by a ZSM-5 Zeolite Packed Multicolumn VPSA Process with the SMB Operation Mode for High-Purity Methane Production

“…There are also titanosilicate , materials similar to zeolites, of which Engelhard titanosilicate-4 (ETS-4) has been mainly studied. The structure of ETS-4 can be deformed by heat treatment or ion exchange techniques to alter the N 2 /CH 4 kinetic equilibrium selectivity. , In addition, many novel materials, such as metal–organic frameworks (MOF), − covalent organic frameworks (COF), and ionic liquids, have been reported. By designing and tuning the structure and function of sorbents, the adsorption performance and CH 4 /N 2 selectivity were improved. , Due to the high cost and poor chemical and thermal stabilities of these advanced sorbents, there are still some challenges in commercial-scale application.…”

“…By designing and tuning the structure and function of sorbents, the adsorption performance and CH 4 /N 2 selectivity were improved. 25,29 Due to the high cost and poor chemical and thermal stabilities of these advanced sorbents, there are still some challenges in commercial-scale application.…”

Zr-Based Metal–Organic Framework with Wall-Shared Dual Ultramicroporous Channels for Effective CH4/N2 Separation

“…Metal–organic frameworks (MOFs) are a class of crystalline porous materials with high controllability and designability that have been extensively studied for gas storage and separation purposes. − For the separation of CH 4 /N 2 , many efforts have also been dedicated to developing CH 4 -selective − or N 2 -selective MOF adsorbents. Among them, the CH 4 -selective separation based on the polarizability difference between CH 4 and N 2 is relatively easier to implement and better suitable for the unconventional gas conditions with low CH 4 concentration.…”