ACS Catalysis Nov 2018 Cover

Abstract

SiO2-supported tungsten catalysts (WO3/SiO2) are currently used in industry to make propene via metathesis of butene and ethylene. Reliable information on structure–activity relationships, aimed at improved catalyst design, continues to be an active area of investigation. On the basis of ex situ XPS and solid-state NMR spectroscopy of calcined W-incorporated mesoporous silicates (W-KIT-6), complemented by computational studies and activity evaluation in a fixed-bed reactor, we demonstrate that W–O–Si species are the active site precursors for 2-butene + ethylene metathesis to produce propene at 450 °C. This conclusion is supported by evidence that the population of W–O–Si species on the calcined W-KIT-6 catalysts is linearly correlated with 2-butene conversion, regardless of W loading. We further show that for a given W loading, the accessible W–O–Si species and thereby the propene yield, can be enhanced by delaying the tungsten source addition during catalyst synthesis. Our results are consistent with previously reported in situ mechanistic studies using complementary analytical tools.

Citation

Jian-Feng Wu, Anand Ramanathan, Alessandro Biancardi, Amy Marie Jystad, Marco Caricato, Yongfeng Hu, and Bala Subramaniam. Correlation of Active Site Precursors and Olefin Metathesis Activity in W-Incorporated Silicates. ACS Catalysis, 2018, 8 (11), 10437-10445