Influence of monovalent alkaline metal cations on binder-free nano-zeolite X in para-xylene separation

doi:10.1016/j.cjche.2014.11.005

Abstract

Abstract: The adsorption process was studied for separating para-xylene fromxylenemixture on modified nano-zeolite X in a breakthrough system. Nano-zeolitic adsorbent with different ratios of SiO₂/Al₂O₃ was synthesized through hydrothermal process and ion-exchanged with alkaline metal cations like lithium, sodium and potassium. The product was characterized by X-ray diffraction, scanning electron microscopy (SEM), nitrogen adsorption, transform electron microscopy (TEM) and in situ Fourier transform infrared (FTIR) spectroscopy. The influence of nano-zeolite water content and desorbent type on the selectivity of para-xylene toward other C₈ aromatic isomers was studied. The optimization of adsorption process was also investigated under variable operation conditions. The isotherm for each isomer of C₈ aromatics and the desorbents possess the adsorption characteristics of Langmuir type. The selectivity factor of para-xylene relative to each of meta-xylene, ortho-xylene and ethylbenzene under the optimum conditions obtained to be 5.36, 2.43 and 3.22, in the order given.

Key words: Nano-zeolite X, Adsorption, C₈ aromatics, Isotherm

摘要： The adsorption process was studied for separating para-xylene fromxylenemixture on modified nano-zeolite X in a breakthrough system. Nano-zeolitic adsorbent with different ratios of SiO₂/Al₂O₃ was synthesized through hydrothermal process and ion-exchanged with alkaline metal cations like lithium, sodium and potassium. The product was characterized by X-ray diffraction, scanning electron microscopy (SEM), nitrogen adsorption, transform electron microscopy (TEM) and in situ Fourier transform infrared (FTIR) spectroscopy. The influence of nano-zeolite water content and desorbent type on the selectivity of para-xylene toward other C₈ aromatic isomers was studied. The optimization of adsorption process was also investigated under variable operation conditions. The isotherm for each isomer of C₈ aromatics and the desorbents possess the adsorption characteristics of Langmuir type. The selectivity factor of para-xylene relative to each of meta-xylene, ortho-xylene and ethylbenzene under the optimum conditions obtained to be 5.36, 2.43 and 3.22, in the order given.

关键词: Nano-zeolite X, Adsorption, C₈ aromatics, Isotherm

Milad Rasouli, Nakisa Yaghobi, Seyedeh Zahra Movassaghi Gilani, Hossein Atashi, Majid Rasouli . Influence of monovalent alkaline metal cations on binder-free nano-zeolite X in para-xylene separation[J]. Chin.J.Chem.Eng., 2015, 23(1): 64-70.

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