The amine-functionalized metal-organic frameworks are regarded as promising adsorbents for capturing CO2 from coal-fired flue gas due to their high porosity,large CO2 adsorption capacity,and good water resistance.However,the aggregation of surface amine molecules during high-temperature desorption processes leads to a drop in both adsorption rate and uptake.In this study,a novel amine-functionalized adsorbent was developed by physically encapsulating tetraethylenepentamine molecules into the pores of MOF-808(TEPA@MOF-808)through a simple impregnation method.Compared to pristine MOF-808,TEPA@MOF-808 exhibited a 2.15-fold increase in CO2 adsorption uptake,along with enhancements of 13％in adsorption rate constant and 498％in adsorption selectivity.After 10 cycles,its adsorption uptake only decreased by 10.9％.Thermodynamic analysis revealed a low heat of adsorption of 40 kJ/mol,suggesting a physical adsorption mechanism.13C SSNMR and in situ DRIFTS characterization further elucidated the CO2 physisorption mechanism of TEPA@MOF-808.
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