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Hierarchical Structure ZSM-5/SBA-15 Composite with Improved Hydrophobicity for Adsorption-Desorption Behavior of Toluene
Chemical Engineering Journal ( IF 15.1 ) Pub Date : 2020-03-22 , DOI: 10.1016/j.cej.2020.124861
Renna Li , Tianshan Xue , Zhe Li , Qiang Wang

Hydrophobic zeolites have been considered as one of the most promising adsorbents for capturing volatile organic compounds (VOCs). In this contribution, hierarchically structured ZSM-5/SBA-15 composites with different morphologies including platelet, hexagonal prism, long-hexagonal prism, and long-rod were prepared. All materials were characterized using XRD, SEM, and TEM-EDX, which confirmed that the high dispersion of two zeolites within the composites. Due to the presence of intracrystalline mesopores that could shorten the diffusion pathway of toluene, the composites resulted in increased effective diffusion and higher adsorption capacity. The composites also possess higher hydrophobicity, leading to much better toluene adsorption performance under humid conditions. The water contact angle of ZSM-5 could be increased from 15.6o to 44.9o by forming well dispersed zeolite composites. The 29Si MAS NMR results confirmed that the composites possess higher amount of Q4 groups (75.3%-80.1%), which is the intrinsic reason for higher hydrophobicity. Notably, ZSM-5/SBA-15-hexagonal prism resulted in the best adsorption performance and cycling stability when compared with pure ZSM-5, the breakthrough time was increased from 20.8 to 49.4 min under dry conditions and from 5.9 to 27.3 min in the presence of 50% relative humidity. This work represents an important scheme for making hydrophobic zeolite-based VOCs adsorbents with also improved toluene diffusion properties due to the unique hierarchical porous structure.



中文翻译:

具有改善的疏水性的层次结构ZSM-5 / SBA-15复合材料对甲苯的吸附-解吸行为

疏水沸石被认为是捕获挥发性有机化合物(VOC)的最有希望的吸附剂之一。在此贡献中,制备了具有不同形态的分层结构的ZSM-5 / SBA-15复合材料,包括血小板,六边形棱柱,长六边形棱柱和长棒。使用XRD,SEM和TEM-EDX对所有材料进行了表征,这证实了两种沸石在复合物中的高度分散性。由于存在晶内中孔可以缩短甲苯的扩散途径,因此复合材料可提高有效扩散和更高的吸附能力。该复合材料还具有较高的疏水性,从而在潮湿条件下具有更好的甲苯吸附性能。ZSM-5的水接触角可以从15.6增加Ò〜44.9 ö通过形成良好分散的沸石复合材料。的29分的Si MAS NMR的结果确认,复合材料具有较高的量Q的4组(75.3%-80.1%),这对于较高的疏水性的内在原因。值得注意的是,与纯ZSM-5相比,ZSM-5 / SBA-15-六棱柱具有最佳的吸附性能和循环稳定性,在干燥条件下,穿透时间从20.8分钟增加到49.4分钟,而在干燥条件下则从5.9分钟增加到27.3分钟相对湿度为50%。这项工作代表了一种重要的方案,用于制备疏水性沸石基VOCs吸附剂,由于独特的分级多孔结构,该吸附剂还具有改善的甲苯扩散性能。

更新日期:2020-03-22
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