化工学报 ›› 2022, Vol. 73 ›› Issue (3): 1194-1206.DOI: 10.11949/0438-1157.20211439

• 分离工程 • 上一篇    下一篇

中空孔结构对W掺杂MFI分子筛丙酮吸附行为的研究

王旭(),张乐瑶,张昊轩,演嘉辉,吴玉帅,吴冬,陈汇勇(),马晓迅   

  1. 西北大学化工学院,陕西 西安 710069
  • 收稿日期:2021-10-21 修回日期:2021-12-03 出版日期:2022-03-15 发布日期:2022-03-14
  • 通讯作者: 陈汇勇
  • 作者简介:王旭(1995—),男,博士研究生,xuwang@stumail.nwu.edu.cn
  • 基金资助:
    国家自然科学基金项目(21978238);陕西省教育厅科学研究计划重点项目(21JY041)

Effect of hollow structure on the acetone adsorption property of tungsten-substituted MFI zeolite

Xu WANG(),Leyao ZHANG,Haoxuan ZHANG,Jiahui YAN,Yushuai WU,Dong WU,Huiyong CHEN(),Xiaoxun MA   

  1. School of Chemical Engineering, Northwest University, Xi’an 710069, Shaanxi, China
  • Received:2021-10-21 Revised:2021-12-03 Online:2022-03-15 Published:2022-03-14
  • Contact: Huiyong CHEN

摘要:

吸附容量高、吸附速率快以及憎水性强是分子筛用于挥发性有机物(VOCs)高效吸附的主要性能指标。分别以纯硅(S-1)和W掺杂(WS-1)MFI分子筛为母体,通过一步水热脱硅/补钨后处理制备了具有全空腔(HWS-1_S)和多孔芯(HWS-1_W)的两种中空结构分子筛,并以典型的VOCs气体分子丙酮为探针,系统研究了中空结构形态对于分子筛吸附性能的影响。结果表明:HWS-1_S表面部分开孔,内部全空腔且与外部连通,相比于母体S-1,相对结晶度较低,微孔孔容减少;HWS-1_W表面开孔细微,内部出现不规则的大/中孔结构,相比母体WS-1,相对结晶度提高,微孔孔容增大。干气条件下,HWS-1_S与HWS-1_W相比母体S-1和WS-1对丙酮具有更快的吸附速率;HWS-1_S微孔孔容损失严重,导致吸附容量有限(27.4 mg·g-1);HWS-1_W由于重结晶修复了部分结构缺陷,提高了丙酮吸附容量(51.2 mg·g-1)。通过吸附动力学拟合,HWS-1_S和HWS-1_W符合典型的孔扩散机理,对丙酮主要以物理吸附为主。湿气条件下,W掺杂可有效中和中空分子筛表面硅醇基团,在一定程度上提高了W掺杂中空分子筛抗水汽竞争吸附能力。

关键词: VOCs, 丙酮, 吸附, W掺杂分子筛, 中空结构, 吸附动力学

Abstract:

Zeolite adsorbents for the adsorption and removal of volatile organic compounds (VOCs) have attracted considerable attention in recent years. However, the low adsorption capacity, slow adsorption rate, and hydrophilic nature strongly restrict the development of zeolite-type VOCs adsorbents. In this paper, tungsten-substituted MFI zeolites (HWS-1_S and HWS-1_W) with two kinds of hollow structures (fully and multichambered) are prepared by post-treating the siliceous MFI (S-1) and tungsten-substituted MFI (WS-1) through desilication and tungstation, respectively. And the effect of the hollow morphology on VOCs adsorption performance is investigated by using acetone as an adsorbate. The results show that HWS-1_S and HWS-1_W exhibit faster adsorption rates for acetone compared to the parent S-1 and WS-1 benefitted from their highly interconnected hollow structures. HWS-1_S shows a limited adsorption capacity (27.4 mg·g-1) of acetone than S-1 due to its reduced micropore volume, while HWS-1_W presents an increased adsorption capacity (51.2 mg·g-1) of acetone compared with WS-1, which could be ascribed to the defect removal by tungstation. Acetone dominatly performs as physical absorption on both HWS-1_S and HWS-1_W based on the fitting results of adsorption kinetics. Moreover, substitution of W atoms within zeolite frameworks can neutralize silanol groups and further enhance the hydrophobicity of zeolite adsorbents, leading an effective resistance of competitive adsorption of water.

Key words: VOCs, acetone, adsorption, tungsten-substituted zeolite, hollow structure, adsorption kinetics

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