A metal-OH group modification strategy to prepare highly-hydrophobic MIL-53-Al for efficient acetone capture under
Jiaqi Shi1, Rui Han1, Shuangchun Lu1
1Tianjin Key Lab of Indoor Air Environmental Quality Control, School of Environmental Science and Technology, Tianjin University, Tianjin 300350, China; State Key Laboratory of Engines, Tianjin University, Tianjin 300350, China.
Abstract:
A series of highly-hydrophobic MIL-53-Al (MIL = Materials of Institut Lavoisier) frameworks synthesized via decoration of the Al-OH groups by alkyl phosphonic acid were developed as adsorbents for removing acetone from humid gas streams. The newly prepared materials were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM), N2 adsorption-desorption and thermogravimetric analysis (TGA). Their adsorption behaviors toward acetone vapor under dry and wet conditions were studied subsequently. Results showed that alkyl phosphonic acid was successfully grafted into MIL-53-Al skeleton through coordinating interaction with Al3+ generating MIL-53-Al@Cx (x = 12, 14, 18). The MIL-53-Al@Cx exhibited similar crystal structure and thermal stability to parent MIL-53-Al. Furthermore, the modified materials showed significantly enhanced hydrophobicity. The water vapor uptake of MIL-53-Al@C14 decreased by 72.55% at 75% relative humidity (RH). Dynamic adsorption experiments demonstrated that water vapor had almost no effect on the acetone adsorption performance of MIL-53-Al@C14. Under the condition of 90% RH, the acetone adsorption capacity of MIL-53-Al@C14 was 102.98% higher than that of MIL-53-Al. Notably, MIL-53-Al@C14 presented excellent adsorption reversibility and regeneration performance in 10 adsorption-desorption cycles. Taken together, the strategy of metal-OH group modification is an attractive way to improve the acetone adsorption performance over metal-organic frameworks (MOFs) under humid conditions. Besides, MIL-53-Al@C14 would be deemed as a promising candidate for capturing acetone in high moisture environment.
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