Although many porous materials, including metal–organic frameworks (MOFs), have been reported to selectively adsorb C2H2in C2H2/CO2separation processes, CO2‐selective sorbents are much less common. Here, we report the remarkable performance of
- Award ID(s):
- 1301346
- NSF-PAR ID:
- 10081705
- Date Published:
- Journal Name:
- Journal of Materials Chemistry A
- Volume:
- 4
- Issue:
- 6
- ISSN:
- 2050-7488
- Page Range / eLocation ID:
- 2263 to 2276
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
Abstract MFU‐4 (Zn5Cl4(bbta)3, bbta=benzo‐1,2,4,5‐bistriazolate) toward inverse CO2/C2H2separation. The MOF facilitates kinetic separation of CO2from C2H2, enabling the generation of high purity C2H2(>98 %) with good productivity in dynamic breakthrough experiments. Adsorption kinetics measurements and computational studies show C2H2is excluded fromMFU‐4 by narrow pore windows formed by Zn−Cl groups. Postsynthetic F−/Cl−ligand exchange was used to synthesize an analogue (MFU‐4‐F ) with expanded pore apertures, resulting in equilibrium C2H2/CO2separation with reversed selectivity compared toMFU‐4 .MFU‐4‐F also exhibits a remarkably high C2H2adsorption capacity (6.7 mmol g−1), allowing fuel grade C2H2(98 % purity) to be harvested from C2H2/CO2mixtures by room temperature desorption. -
Abstract Although many porous materials, including metal–organic frameworks (MOFs), have been reported to selectively adsorb C2H2in C2H2/CO2separation processes, CO2‐selective sorbents are much less common. Here, we report the remarkable performance of
MFU‐4 (Zn5Cl4(bbta)3, bbta=benzo‐1,2,4,5‐bistriazolate) toward inverse CO2/C2H2separation. The MOF facilitates kinetic separation of CO2from C2H2, enabling the generation of high purity C2H2(>98 %) with good productivity in dynamic breakthrough experiments. Adsorption kinetics measurements and computational studies show C2H2is excluded fromMFU‐4 by narrow pore windows formed by Zn−Cl groups. Postsynthetic F−/Cl−ligand exchange was used to synthesize an analogue (MFU‐4‐F ) with expanded pore apertures, resulting in equilibrium C2H2/CO2separation with reversed selectivity compared toMFU‐4 .MFU‐4‐F also exhibits a remarkably high C2H2adsorption capacity (6.7 mmol g−1), allowing fuel grade C2H2(98 % purity) to be harvested from C2H2/CO2mixtures by room temperature desorption. -
Abstract The Raman spectral behavior of N2, CO2, and CH4in ternary N2–CO2–CH4mixtures was studied from 22°C to 200°C and 10 to 500 bars. The peak position of N2in all mixtures is located at lower wavenumbers compared with pure N2at the same pressure (
P )–temperature (T ) (PT ) conditions. The Fermi diad splitting in CO2is greater in the pure system than in the mixtures, and the Fermi diad splitting increases in the mixtures as CO2concentration increases at constantP andT . The peak position of CH4in the mixtures is shifted to higher wavenumbers compared with pure CH4at the samePT conditions. However, the relationship between peak position and CH4mole fraction is more complicated compared with the trends observed with N2and CO2. The relative order of the peak position isotherms of CH4and N2in the mixtures in pressure–peak position space mimics trends in the molar volume of the mixtures in pressure–molar volume space. Relationships between the direction of peak shift of individual components in the mixtures, the relative molar volumes of the mixtures, and the attraction and repulsion forces between molecules are developed. Additionally, the relationship between the peak position of N2in ternary N2–CO2–CH4mixtures with pressure is extended to other N2‐bearing systems to assess similarities in the Raman spectral behavior of N2in various systems. -
Abstract The high energy footprint of commodity gas purification and increasing demand for gases require new approaches to gas separation. Kinetic separation of gas mixtures through molecular sieving can enable separation by molecular size or shape exclusion. Physisorbents must exhibit the right pore diameter to enable separation, but the 0.3–0.4 nm range relevant to small gas molecules is hard to control. Herein, dehydration of the ultramicroporous metal–organic framework Ca‐trimesate, Ca(HBTC)⋅H2O (H3BTC=trimesic acid), bnn‐1‐Ca‐H2O, affords a narrow pore variant, Ca(HBTC), bnn‐1‐Ca. Whereas bnn‐1‐Ca‐H2O (pore diameter 0.34 nm) exhibits ultra‐high CO2/N2, CO2/CH4, and C2H2/C2H4binary selectivity, bnn‐1‐Ca (pore diameter 0.31 nm) offers ideal selectivity for H2/CO2and H2/N2under cryogenic conditions. Ca‐trimesate, the first physisorbent to exhibit H2sieving under cryogenic conditions, could be a prototype for a general approach to exert precise control over pore diameter in physisorbents.
-
Abstract The high energy footprint of commodity gas purification and increasing demand for gases require new approaches to gas separation. Kinetic separation of gas mixtures through molecular sieving can enable separation by molecular size or shape exclusion. Physisorbents must exhibit the right pore diameter to enable separation, but the 0.3–0.4 nm range relevant to small gas molecules is hard to control. Herein, dehydration of the ultramicroporous metal–organic framework Ca‐trimesate, Ca(HBTC)⋅H2O (H3BTC=trimesic acid), bnn‐1‐Ca‐H2O, affords a narrow pore variant, Ca(HBTC), bnn‐1‐Ca. Whereas bnn‐1‐Ca‐H2O (pore diameter 0.34 nm) exhibits ultra‐high CO2/N2, CO2/CH4, and C2H2/C2H4binary selectivity, bnn‐1‐Ca (pore diameter 0.31 nm) offers ideal selectivity for H2/CO2and H2/N2under cryogenic conditions. Ca‐trimesate, the first physisorbent to exhibit H2sieving under cryogenic conditions, could be a prototype for a general approach to exert precise control over pore diameter in physisorbents.