Over the last two decades, polymers with superior H2/CO2separation properties at 100–300 °C have gathered significant interest for H2purification and CO2capture. This timely review presents various strategies adopted to molecularly engineer polymers for this application. We first elucidate the Robeson's upper bound at elevated temperatures for H2/CO2separation and the advantages of high‐temperature operation (such as improved solubility selectivity and absence of CO2plasticization), compared with conventional membrane gas separations at ~35 °C. Second, we describe commercially relevant membranes for the separation and highlight materials with free volumes tuned to discriminate H2and CO2, including functional polymers (such as polybenzimidazole) and engineered polymers by cross‐linking, blending, thermal treatment, thermal rearrangement, and carbonization. Third, we succinctly discuss mixed matrix materials containing size‐sieving or H2‐sorptive nanofillers with attractive H2/CO2separation properties.
Described for the first time is that carbon dioxide (CO2) can be successfully inserted into aryl C−H bonds of the backbone of a metal–organic framework (MOF) to generate free carboxylate groups, which serve as Brønsted acid sites for efficiently catalyzing the methanolysis of epoxides. The work delineates the very first example of utilizing CO2for heterogeneous C−H activation and carboxylation reactions on MOFs, and opens a new avenue for CO2chemical transformations under mild reaction conditions.
more » « less- NSF-PAR ID:
- 10215314
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Angewandte Chemie
- Volume:
- 128
- Issue:
- 18
- ISSN:
- 0044-8249
- Page Range / eLocation ID:
- p. 5562-5566
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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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. -
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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. -
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Abstract Porous materials with open metal sites have been investigated to separate various gas mixtures. However, open metal sites show the limitation in the separation of some challenging gas mixtures, such as C2H2/CO2. Herein, we propose a new type of ultra‐strong C2H2nano‐trap based on multiple binding interactions to efficiently capture C2H2molecules and separate C2H2/CO2mixture. The ultra‐strong acetylene nano‐trap shows a benchmark
Qst of 79.1 kJ mol−1for C2H2, a record high pure C2H2uptake of 2.54 mmol g−1at 1×10−2 bar, and the highest C2H2/CO2selectivity (53.6), making it as a new benchmark material for the capture of C2H2and the separation of C2H2/CO2. The locations of C2H2molecules within the MOF‐based nanotrap have been visualized by the in situ single‐crystal X‐ray diffraction studies, which also identify the multiple binding sites accountable for the strong interactions with C2H2. -
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Abstract Porous materials with open metal sites have been investigated to separate various gas mixtures. However, open metal sites show the limitation in the separation of some challenging gas mixtures, such as C2H2/CO2. Herein, we propose a new type of ultra‐strong C2H2nano‐trap based on multiple binding interactions to efficiently capture C2H2molecules and separate C2H2/CO2mixture. The ultra‐strong acetylene nano‐trap shows a benchmark
Qst of 79.1 kJ mol−1for C2H2, a record high pure C2H2uptake of 2.54 mmol g−1at 1×10−2 bar, and the highest C2H2/CO2selectivity (53.6), making it as a new benchmark material for the capture of C2H2and the separation of C2H2/CO2. The locations of C2H2molecules within the MOF‐based nanotrap have been visualized by the in situ single‐crystal X‐ray diffraction studies, which also identify the multiple binding sites accountable for the strong interactions with C2H2.
