Optimization of conditions for preparation of ZSM-5@silicalite-1 core-shell catalysts via hydrothermal synthesis

doi:10.1016/j.cjche.2018.03.030

Abstract

Abstract: Although the preparation of ZSM-5@silicalite-1 (ZS) core-shell catalysts has been reported in the literature, their selectivity to para-xylene (PX) in the toluene alkylation with methanol is difficult to control. Here we present the effects of water and ZSM-5 adding amounts in the synthesis solution, the hydrothermal synthesis time, and the Si/Al ratio of core ZSM-5 on the catalytic performance of ZS core-shell catalysts. The ZS core-shell catalysts were characterized by X-ray diffraction (XRD), N₂ adsorption, and NH₃ temperature-programmed desorption (NH₃-TPD) techniques. The highest PX selectivity of 95.5% was obtained for the ZS (Si/Al=140) catalyst prepared in the synthesis solution with a molar ratio of 0.2TPAOH:1TEOS:250H₂O at 175℃ and 10 r·min^-1 for only 2 h and the corresponding toluene conversion is as high as 22.8% for the alkylation of toluene with methanol.

Key words: ZSM-5, Silicalite-1, Core-shell catalyst, Alkylation, Para-selectivity

摘要： Although the preparation of ZSM-5@silicalite-1 (ZS) core-shell catalysts has been reported in the literature, their selectivity to para-xylene (PX) in the toluene alkylation with methanol is difficult to control. Here we present the effects of water and ZSM-5 adding amounts in the synthesis solution, the hydrothermal synthesis time, and the Si/Al ratio of core ZSM-5 on the catalytic performance of ZS core-shell catalysts. The ZS core-shell catalysts were characterized by X-ray diffraction (XRD), N₂ adsorption, and NH₃ temperature-programmed desorption (NH₃-TPD) techniques. The highest PX selectivity of 95.5% was obtained for the ZS (Si/Al=140) catalyst prepared in the synthesis solution with a molar ratio of 0.2TPAOH:1TEOS:250H₂O at 175℃ and 10 r·min^-1 for only 2 h and the corresponding toluene conversion is as high as 22.8% for the alkylation of toluene with methanol.

关键词: ZSM-5, Silicalite-1, Core-shell catalyst, Alkylation, Para-selectivity

Chuang Liu, Yihua Long, Zhengbao Wang. Optimization of conditions for preparation of ZSM-5@silicalite-1 core-shell catalysts via hydrothermal synthesis[J]. Chin.J.Chem.Eng., 2018, 26(10): 2070-2076.

Chuang Liu, Yihua Long, Zhengbao Wang. Optimization of conditions for preparation of ZSM-5@silicalite-1 core-shell catalysts via hydrothermal synthesis[J]. Chinese Journal of Chemical Engineering, 2018, 26(10): 2070-2076.

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