Selective Capture of Carbon Dioxide under Humid Conditions by Hydrophobic Chabazite‐Type Zeolitic Imidazolate Frameworks

Abstract

Hydrophobic zeolitic imidazolate frameworks (ZIFs) with the chabazite (CHA) topology are synthesized by incorporating two distinct imidazolate links. Zn(2-mIm)0.86 (bbIm)1.14 (ZIF-300), Zn(2-mIm)0.94 (cbIm)1.06 (ZIF-301), and Zn(2-mIm)0.67 (mbIm)1.33 (ZIF-302), where 2-mIm = 2-methylimidazolate, bbIm = 5(6)-bromobenzimidazolate, cbIm = 5(6)-chlorobenzimidazolate, and mbIm = 5(6)-methylbenzimidazolate, were prepared by reacting zinc nitrate tetrahydrate and 2-mIm with the respective bIm link in a mixture of N,N-dimethylformamide (DMF) and water. Their structures were determined by single-crystal X-ray diffraction and their permanent porosity shown. All of these structures are hydrophobic as confirmed by water adsorption isotherms. All three ZIFs are equally effective at the dynamic separation of CO2 from N2 under both dry and humid conditions without any loss of performance over three cycles and can be regenerated simply by using a N2 flow at ambient temperature.

Multifunctional metal–organic frameworks: from academia to industrial applications

“…Nevertheless, some reports have also emerged describing the selective adsorption of CO 2 over other gases (i.e., N 2 , CH 4 , O 2 , C 2 H 2 or CO), some of which even comprise binary (e.g., CO 2 /CO, CO 2 /N 2 or CO 2 /CH 4 ) and ternary (CO 2 /N 2 /CH 4 , CO 2 /N 2 /H 2 O or CO 2 /N 2 /O 2 ) gas mixtures. 116,117,[125][126][127][128][129][130][131][132] Wang et al reported two porous zeolite-type imidazolate frameworks, coined as ZIF-95 and ZIF-100, possessing complex cages with 264 vertices and constructed from about 7524 atoms. 125 After breakthrough experiments it was discovered that these ZIFs have a great ability to selective adsorb CO 2 from mixtures of CO 2 /CH 4 , CO 2 /CO and CO 2 /N 2 (50:50 v/v).…”

Carbon capture turned upside down: high-temperature adsorption & low-temperature desorption (HALD)

“…(MOFs), 14,15 zeolitic imidazolate frameworks (ZIFs) 16,17 and porous polymer networks (PPNs). 18,19 In the current work, we focus on zeolites.…”

Structural single and multiple molecular adsorption of CO 2 and H 2 O in zeolitic imidazolate framework (ZIF) crystals

“…Numerous studies pointed out the presence of CO 2 and water inside these porous materials [7,8]. Due to propitious structural properties and electronic distributions at the microscopic level, industrial complications are encountered because of the competition between water and CO 2 during the separation or storage processes.…”