期刊
CHEMISTRY-A EUROPEAN JOURNAL
卷 27, 期 14, 页码 4746-4754出版社
WILEY-V C H VERLAG GMBH
DOI: 10.1002/chem.202005216
关键词
carbon capture; heterogeneous catalysis; metal– organic frameworks; nitrogen ligands
资金
- Universita dell'Insubria
- Italian MIUR through the PRIN [20179337R7]
- TRAINER project (Catalysts for Transition to Renewable Energy Future) [ANR-17-MPGA-0017]
This study synthesized zinc bipyrazolate metal-organic frameworks with different coordinating ligands, and through textural analysis and experimental testing, revealed their potential applications in CO2 adsorption and epoxidation reactions.
Aiming at extending the tagged zinc bipyrazolate metal-organic frameworks (MOFs) family, the ligand 3,3'-diamino-4,4'-bipyrazole (3,3'-H2L) has been synthesized in good yield. The reaction with zinc(II) acetate hydrate led to the related MOF Zn(3,3'-L). The compound is isostructural with its mono(amino) analogue Zn(BPZNH(2)) and with Zn(3,5-L), its isomeric parent built with 3,5-diamino-4,4'-bipyrazole. The textural analysis has unveiled its micro-/mesoporous nature, with a BET area of 463 m(2) g(-1). Its CO2 adsorption capacity (17.4 wt. % CO2 at p(CO2) = 1 bar and T = 298 K) and isosteric heat of adsorption (Q(st) = 24.8 kJ mol(-1)) are comparable to that of Zn(3,5-L). Both Zn(3,3'-L) and Zn(3,5-L) have been tested as heterogeneous catalysts in the reaction of CO2 with the epoxides epichlorohydrin and epibromohydrin to give the corresponding cyclic carbonates at T = 393 K and p(CO2) = 5 bar under solvent- and co-catalyst-free conditions. In general, the conversions recorded are higher than those found for Zn(BPZNH(2)), proving that the insertion of an extra amino tag in the pores is beneficial for the epoxidation catalysis. The best catalytic match has been observed for the Zn(3,5-L)/epichlorohydrin couple, with 64 % conversion and a TOF of 5.3 mmol(carbonate) (mmol(Zn))(-1) h(-1). To gain better insights on the MOF-epoxide interaction, the crystal structure of the [epibromohydrin@Zn(3,3'-L)] adduct has been solved, confirming the existence of Br...(H)-N non-bonding interactions. To our knowledge, this study represents the first structural determination of a [epibromohydrin@MOF] adduct.
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