Ammonia adsorption and its effects on framework stability of MOF-5 and MOF-177
Ammonia adsorption and its effects on framework stability of MOF-5 and MOF-177
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DOI：
10.1016/j.jcis.2010.04.078
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发表时间：
2010-08-15
影响因子：
9.9
通讯作者：
Deng, Shuguang
中科院分区：
文献类型：
--
作者：
Saha, Dipendu;Deng, Shuguang
测定了MOF-5和MOF-177在298 K和800 torr的氨压力下的氨吸附平衡和动力学。这项研究使我们能够确定两种MOFs在暴露于氨后的氨吸附性能和稳定性。在低于150 torr的氨压力下，MOF-177对氨的吸附量大于MOF-5，在800 torr时，MOF-177对氨的吸附量基本相同（12.2 mmol/g）。从吸附结果可以推断，在氨压力低于150 torr时，两种MOF骨架对氨的物理吸附均占主导地位，之后氨与MOF骨架发生化学反应。暴露于氨后，两种mof都失去了大部分的孔隙结构，比表面积和孔隙体积急剧下降。x射线衍射研究表明MOF-5和MOF-177的结晶度完全丧失，FT-IR和拉曼光谱分析表明MOF-5和MOF-177暴露于氨后都产生了游离有机配体。氨分子通过与MOF的zn40o簇形成氢键来破坏MOF骨架。(C) 2010爱思唯尔公司版权所有。
Ammonia adsorption equilibrium and kinetics on MOF-5 and MOF-177 were measured volumetrically at 298 K and ammonia pressures up to 800 torr. This study allowed us to determine the ammonia adsorption properties and stability of both MOFs after exposure to ammonia. MOF-177 adsorbed more ammonia than MOF-5 at ammonia pressures below 150 torr and the ammonia adsorption capacity on both MOFs at 800 torr was about the same (12.2 mmol/g). It can be inferred from the adsorption results that physical adsorption of ammonia on both MOFs dominated at ammonia pressures below 150 torr after which chemical reactions between ammonia and MOF frameworks take place. After exposure to ammonia both MOFs lost majority of their pore textures as evidenced by a drastic decrease of specific surface area and pore volume. The X-ray diffraction study suggested a complete loss of crystallinity of both MOFs, and the FT-IR and Raman spectral analyses showed the generation of free organic ligands within both MOF-5 and MOF-177 after they were exposed to ammonia. Ammonia molecules are proposed to destroy the MOF frameworks by forming hydrogen bonds with Zn4O clusters of MOFs. (C) 2010 Elsevier Inc. All rights reserved.