Tetrahedrally coordinated W(VI) species induced Lewis acid for stable catalytic cracking of 1-hexene to propene.

We prepared a series of highly dispersed tetrahedrally coordinated tungsten catalysts with different Si/Al ratios by a simple "top-down" method for catalytic cracking of 1-hexene to propene. High 1-hexene conversion (>97%) and propene selectivity (>40%) could be maintained at 575°C over the W-ZSM-5(60) catalyst. [Display omitted] • Stability of the Si-O-Al structure in the W-ZSM-5 framework was enhanced. • Active tetrahedrally coordinated W (VI) species were highly dispersed on ZSM-5 catalysts. • Superior propene selectivity was achieved over W-ZSM-5 (60) catalysts. • The mechanism of W-ZSM-5 on the 1-hexene cracking reaction path were clarified. Reasonable regulation of the acidity of ZSM-5 could fundamentally improve the catalytic performance for the cracking of low-carbon olefins to propene. Herein, a series of ZSM-5 catalysts with highly dispersed tetrahedrally coordinated W(VI) species were prepared for the catalytic cracking of 1-hexene to propene by a simple "top-down" method. Multi-characterizations revealed that the introduction of W enhanced the stability of the Si-O-Al structure in W-ZSM-5 by eliminating the non-skeleton aluminum and excessive Brønsted acid sites, leading to a superb resistance to carbon/coke deposition. Moreover, the Lewis acid sites originated from the active tetrahedrally coordinated W (VI) species improved the propene selectivity via inhibiting the polymerization of products. In addition, through the optimization of various parameters (such as Si/Al ratio, temperature and weight hourly space velocity), high 1-hexene conversion (>97%) and propene selectivity (>40%) could be maintained at 575 °C over the W-ZSM-5(60) catalyst during 30 h long period reaction. This work may provide some new insights for the effect of W-based catalysts on acid composition in the cracking of light olefins to propene. [ABSTRACT FROM AUTHOR]