胺基功能化金属有机骨架具有孔隙率高、CO2吸附容量大、抗水性好的优点,被认为是适用于燃煤烟气CO2捕集的吸附材料,但其表面胺基分子在高温脱附过程易发生团聚,导致吸附速率和吸附容量下降。采用物理浸渍将四乙烯五胺分子(TEPA)封装入MOF-808的孔道内,开发了一种胺基分子高度分散的胺基功能化吸附材料TEPA@MOF-808。TEPA@MOF-808的吸附容量相比MOF-808提高了2.15倍,吸附速率常数、吸附选择性分别提高了13%和498%,10次吸脱附循环后吸附容量仅下降10.9%,说明基于TEPA的胺基功能化策略可显著提高CO2吸附性能和稳定性。热力学结果显示TEPA@MOF-808的等量吸附热仅为40kJ/mol,小于普遍认为的化学吸附门槛,13C固体核磁和原位红外表征结果进一步揭示了其以物理吸附为主的吸附机理。

The amine-functionalized metal-organic frameworks are regarded as promising adsorbents for capturing CO2 from coal-firedflue gas due to their high porosity,large CO2 adsorption capacity,and good water resistance. However,the aggregation of surface aminemolecules 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-foldincrease in CO2 adsorption uptake,along with enhancements of 13% in adsorption rate constant and 498% in adsorption selectivity. After10 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. C SSNMR and in situ DRIFTS characterization further elucidated the CO2 physisorptionmechanism of TEPA@MOF-808.

0 引言

1 试验

   1.1 试剂

   1.2 样品合成

   1.3 材料表征

   1.4 吸附性能测试

   1.5 吸附热数据分析

   1.6 动力学分析

2 结果和讨论

   2.1 吸附材料微观形貌与结构特性

   2.2 CO2吸附性能

   2.3 CO2吸附机理

3 结论