Preparation of Zn-modified nano-ZSM-5 zeolite and its catalytic performance in aromatization of 1-hexene
(1. Key Laboratory of Chemical Engineering Process & Technology for High-Efficiency Conversion,
School of Chemistry and Materials Sciences, Heilongjiang University, Harbin 150080, China;
2. Boreskov Institute of Catalysis, Siberian Branch of the Russian Academy of Sciences,
Novosibirsk 630090, Russia)
School of Chemistry and Materials Sciences, Heilongjiang University, Harbin 150080, China;
2. Boreskov Institute of Catalysis, Siberian Branch of the Russian Academy of Sciences,
Novosibirsk 630090, Russia)
Abstract: The promoting effect of introducing Zn into nano-ZSM-5 zeolites by conventional impregnation method and isomorphous substitution on the performance of 1-hexene aromatization was investigated. The nano-ZSM-5 zeolite was synthesized by a seed-induced method without organic templates. The Zn-modified nano-ZSM-5 zeolite catalysts, xZn/HNZ5 and yZn/Al-HNZ5, were prepared by the conventional impregnation method and isomorphous substitution, respectively. The structure, chemical composition and acidity of the catalysts were characterized by XRD, XRF, N2 adsorption, SEM, NH3-TPD and Py-IR, while the catalytic properties were evaluated at 480 °C and a weight hourly space velocity (WHSV) of 2.0 h-1 in the aromatization procedure of 1-hexene. Compared with xZn/HNZ5, yZn/Al-HNZ5 exhibited smaller particles and higher dispersion of Zn species, which led to greater intergranular mesopore and homogeneous acidity distribution. Experimental results indicated that the synergy effect between the Br？nsted and Lewis acid sites of the isomorphously substituted nano-ZSM-5 zeolites could significantly increase aromatics yield and improve catalytic stability in the 1-hexene aromatization.
Key words: nano-ZSM-5 zeolite; Zn-modification; catalytic performance; isomorphous substitution; aromatization