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Selective Adsorption of p ‐Cresol from a Mixture of m ‐Cresol and p ‐Cresol over ZSM‐5 with Controlled Micro‐ and Mesoporosity
Author(s) -
Lv Jianhua,
Xu Zeqiang,
Guo Yong,
Wang Hefang,
Liu Jidong
Publication year - 2019
Publication title -
chemistryselect
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.437
H-Index - 34
ISSN - 2365-6549
DOI - 10.1002/slct.201901432
Subject(s) - adsorption , zsm 5 , p cresol , mesoporous material , selectivity , cresol , zeolite , diffusion , chemistry , desorption , chemical engineering , molecular sieve , chromatography , materials science , catalysis , phenol , organic chemistry , physics , engineering , thermodynamics
Abstract Ammonium hexafluorosilicate (AHFS) 1 at different concentrations was utilized as a mesopore‐generating agent to synthesize hierarchical ZSM‐5 (Si‐ZSM‐5) adsorbents; K + ‐exchanged hierarchical ZSM‐5 (K−Si‐ZSM‐5) was successfully prepared by an impregnation method. The properties of adsorbents were characterized using XRD, XRF, N 2 adsorption‐desorption and NH 3 ‐TPD. The selectivity separation of p‐cresol 2 and m‐cresol 3 on adsorbents were experimentally investigated using a liquid breakthrough method. The enhanced adsorption capacity of Si‐ZSM‐5 is attributed to the creation of mesopores, which probably led to higher adsorption diffusion. The introduction of K + into hierarchical ZSM‐5 diminishes the acid sites, strengthens adsorption sites, and reduces the mesopore diameter. Thus, K−Si‐ZSM‐5 possessed higher separation efficiency compared with the parent HZSM‐5. The concentration of AHFS had significant impact on adsorption capacity and the separation efficiency of adsorbents, and AHFS at a concentration of 0.5 M exhibited the optimal adsorption performance. Furthermore, the adsorbent is easy to prepare under laboratory conditions, and through a large scaled‐up breakthrough experiment, it is suitable for practical industrial applications. Also, we propose separation mechanisms of m‐cresol 3 and p‐cresol 2 , and these are mainly controlled by shape selection and adsorbent‐adsorbent interactions.