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ZIF-21 Crystals: Its Morphology Control and Potential as an Adsorbent for Ammonia Capture
Qiushi Wei ; James M. Crawford ; Colin A. Wolden , et al. J. Phys. Chem. C,2022,126(30):12951-12957. DOI: 10.1021/acs.jpcc.2c04191
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Abstract: The selective adsorption of NH3 over N2 and H2 is of interest for ammonia separation and synthesis. Zeolitic imidazolate frameworks (ZIFs) having tunable pores, high surface area, and chemical affinity for ammonia are suitable candidates for this particular application. Herein, we explore the influence of synthesis parameters on the morphology of ZIF-21 formed by hydrothermal synthesis. Among the many variables examined, it was found that the addition of weak bases such us sodium formate (SF) and weak acids such as ethylenediaminetetraacetic acid (EDTA) acts as crystal morphology modifiers to improve the crystallinity and morphology of ZIF-21 crystals. The addition of EDTA led to the formation of crystals with significant improvements in ammonia adsorption performance without modifying the characteristic LTA topology of ZIF-21. The resultant ZIF-21 crystals led to octahedral uniform shapes displaying remarkably high NH3/N2 and NH3/H2 ideal selectivities. Specifically, ideal selectivities of NH3/N2 = 400 and NH3/H2 = 390 were observed, which correspond to an ~7- and 8-fold improvement as compared to pristine ZIF-21 (without the addition of EDTA), respectively. Besides the improved and regular ZI-21 morphology, two main factors led to the high observed NH3/N2 and NH3/H2 ideal selectivities of the EDTA-assisted ZIF-21 crystals: ammonia pore size confinement and enhanced polar–polar interactions between NH3 and polar ZIF-21 walls. Extended exposure to ammonia partially degraded the ZIF-21 crystal structure by reaction with the purine linkers.
Purchased from AmBeed: 120-73-0
CAS No. : | 120-73-0 | MDL No. : | MFCD00079221 |
Formula : | C5H4N4 | Boiling Point : | No data available |
Linear Structure Formula : | HNCHNC4H2N2 | InChI Key : | KDCGOANMDULRCW-UHFFFAOYSA-N |
M.W : | 120.11 | Pubchem ID : | 1044 |
Synonyms : |
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Chemical Name : | 1H-Purine |
Signal Word: | Warning | Class: | |
Precautionary Statements: | P261-P305+P351+P338 | UN#: | |
Hazard Statements: | H315-H319-H335 | Packing Group: | |
GHS Pictogram: |
* All experimental methods are cited from the reference, please refer to the original source for details. We do not guarantee the accuracy of the content in the reference.
Yield | Reaction Conditions | Operation in experiment |
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With N,N?-bis(2,6-diisopropylphenyl)imidazol-2-ylidene hydrochloride; phenylsilane; In tetrahydrofuran; at 70℃; under 750.075 - 2250.23 Torr; for 24h;Schlenk technique; Inert atmosphere; Glovebox; | General procedure: A-Synthesis of Benzimidazole and Derivatives from Aromatic 1,2-DiaminesThe first results presented describe the synthesis of benzimidazole rings and derivatives from aromatic 1,2-diamines. In this case, the amine R1NH2 and the nitrogenous nucleophilic agent R5R6NH are two reactive functional groups of one and the same molecule (diamine) and are thus connected via a covalent bond. This bond is preferably an aromatic ring of benzene, pyridine or pyrimidine type and the ring formed during the reaction is a nitrogenous heterocycle comprising 5 atoms of imidazole type. In the case where the nucleophile is oxygen-based (R7OH), the rings obtained are benzoxazoles. The results presented were produced by preferably using two sources of different reducing agents, polymethylhydrosiloxane (PMHS), sold by Aldrich under the reference 176206, and phenylsilane (PhSiH3), sold by Aldrich. In the case of the PMHS, as a silane is a polymer, the number of equivalents introduced is given with respect to the number of hydrides introduced and thus the number of monomers introduced with respect to the amine. Thus, the introduction of 3 equivalents of PMHS corresponds to the introduction of 3 equivalents of hydride and thus 3 equivalents of monomers of the PMHS with respect to the amine. Different (pre)catalysts were tested for the reaction. |
[ 6055-72-7 ]
7H-Purin-6-amine hydrochloride hydrate (2:2:1)
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