Evaluation of MOFs for air purification and air quality control applications: Ammonia removal from air
Evaluation of MOFs for air purification and air quality control applications: Ammonia removal from air
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DOI：
10.1016/j.ces.2014.08.050
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发表时间：
2015-03-03
影响因子：
4.7
通讯作者：
Walton, Krista S.
中科院分区：
文献类型：
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作者：
Jasuja, Himanshu;Peterson, Gregory W.;Walton, Krista S.
UiO-66 是一种基于 Zr 的 MOF，由于其具有前所未有的热、化学和机械稳定性，正在广泛研究用于各种小分子气体分离。在这项工作中，我们研究了 UiO-66 的各种功能化变体（UiO-66-OH、UiO-66-(OH)(2)、UiO-66-NO2、UiO-66-NH2、UiO-66-SO3H 和 UiO-66-(COOH)(2)）在去除空气中氨方面的性能。功能化 UiO-66 类似物采用溶剂热法合成，并使用干燥和潮湿 (80% RH) 空气条件下的氨突破测量、粉末 X 射线衍射 (PXRD) 图案以及 N-2 吸附等温线的 BET 建模结果进行表征。与化学直觉相反，我们的研究表明 UiO-66-SO3H 和 UiO-66-(COOH)(2) 的氨容量低于 UiO-66-OH 和 UiO-66-NH2。这是由于用大体积官能团（例如-COOH和-SO3H）进行官能化后，骨架孔隙率（表面积和孔体积）显着降低。 -OH基团是工作中考虑的体积最小的官能团，并且与氨有良好的相互作用。在干燥条件下，UiO-66-OH 对氨的容量类似于 5.7 mmol/g，非常接近 0.1 g/g MOF 的氨去除目标（或类似于 6 mmol/g）。然而，我们观察到，由于水和氨分子在活性位点上吸附的竞争，功能化 UiO-66 变体在潮湿条件下的氨容量降低。总体而言，平衡水吸附行为和氨的高选择性和高容量对于开发用于从空气中去除氨的新型吸附剂至关重要。 (C) 2014 Elsevier Ltd. 保留所有权利。
UiO-66 is a Zr-based MOF that is being highly investigated for a wide variety of small molecule gas separations since it possess unprecedented thermal, chemical, and mechanical stability. In this work, we have investigated the performance of various functionalized variations of UiO-66 (UiO-66-OH, UiO-66-(OH)(2), UiO-66-NO2, UiO-66-NH2, UiO-66-SO3H, and UiO-66-(COOH)(2)) towards ammonia removal from air. Functionalized UiO-66 analogs have been synthesized solvothermally and characterized using ammonia breakthrough measurements under dry and humid (80% RH) air conditions along with powder X-ray diffraction (PXRD) patterns and results from BET modeling of N-2 adsorption isotherms. Counter to chemical intuition, our study demonstrates that the ammonia capacities of UiO-66-SO3H and UiO-66-(COOH)(2) are lower than UiO-66-OH and UiO-66-NH2. This is due to significant reduction in the framework porosity (surface area and pore volume) upon functionalization with bulky functional groups such as -COOH and -SO3H. The -OH group is the least bulky functional group considered in the work and interacts favorably with ammonia. UiO-66-OH has a capacity of similar to 5.7 mmol/g for ammonia under dry conditions which is very close to the ammonia removal goal of 0.1 g/g MOF (or similar to 6 mmol/g). However, we observed a decrease in the ammonia capacities of functionalized UiO-66 variations under humid conditions due to competition between water and ammonia molecules for adsorption on the active sites. Overall, balancing the water adsorption behavior and high selectivity and high capacity for ammonia is crucial to developing new adsorbents for ammonia removal from air. (C) 2014 Elsevier Ltd. All rights reserved.