Dong Hong, Li Lihua, Li Can
State Key Laboratory of Catalysis, Dalian National Laboratory for Clean Energy, Dalian Institute of Chemical Physics, Chinese Academy of Sciences Dalian 116023 China
Chem Sci. 2023 Jul 15;14(32):8507-8513. doi: 10.1039/d3sc03213b. eCollection 2023 Aug 16.
Low-concentration CO capture is particularly challenging because it requires highly selective adsorbents that can effectively capture CO from gas mixtures containing other components such as nitrogen and water vapor. In this study, we have successfully developed a series of controlled alkali-etched MOF-808- (where ranges from 0.04 to 0.10), the FT-IR and XPS characterizations revealed the presence of hydroxyl groups (-OH) on the zirconium clusters. Low-concentration CO capture experiments demonstrated improved CO capture performance of the MOF-808- series compared to the pristine MOF-808 under dry conditions (400 ppm CO). Among them, MOF-808-0.07 with abundant Zr-OH sites showed the highest CO capture capacity of 0.21 mmol g under dry conditions, which is 70 times higher than that of pristine MOF-808. Additionally, MOF-808-0.07 exhibited fast adsorption kinetics, stable CO capture under humid air conditions (with a relative humidity of 30%), and stable regeneration even after 50 cycles of adsorption and desorption. DRIFTS and C CP-MAS ssNMR characterizations revealed that the enhanced low-concentration CO capture is attributed to the formation of a stable six-membered ring structure through the interaction of intramolecular hydrogen bonds between neighboring Zr-OH sites a chemisorption mechanism.
低浓度CO捕获极具挑战性，因为它需要高选择性吸附剂，能够从含有氮气和水蒸气等其他成分的气体混合物中有效捕获CO。在本研究中，我们成功开发了一系列可控碱蚀刻的MOF-808-（其中范围为0.04至0.10），傅里叶变换红外光谱（FT-IR）和X射线光电子能谱（XPS）表征揭示了锆簇上存在羟基（-OH）。低浓度CO捕获实验表明，在干燥条件下（400 ppm CO），MOF-808-系列的CO捕获性能比原始MOF-808有所提高。其中，具有丰富Zr-OH位点的MOF-808-0.07在干燥条件下显示出最高的CO捕获容量，为0.21 mmol g，比原始MOF-808高70倍。此外，MOF-808-0.07表现出快速的吸附动力学，在潮湿空气条件下（相对湿度为30%）具有稳定的CO捕获能力，并且即使在50次吸附和解吸循环后仍具有稳定的再生性能。漫反射红外傅里叶变换光谱（DRIFTS）和碳交叉极化魔角旋转固体核磁共振（C CP-MAS ssNMR）表征表明，增强的低浓度CO捕获归因于相邻Zr-OH位点之间通过分子内氢键相互作用形成稳定的六元环结构——一种化学吸附机制。
