Enhanced Olefin Metathesis Performance of Tungsten and Niobium Incorporated Bimetallic Silicates: Evidence of Synergistic Effects
Jianfeng Wu, Anand Ramanathan, Reinhard Kersting, Amy Jystad, Hongda Zhu, Yongfeng Hu, Craig P. Marshall, Marco Caricato, Bala Subramaniam
Abstract
Abstract Tungsten and niobium incorporated KIT‐6 (WNb‐KIT‐6) materials were synthesized by a one‐pot sol‐gel method. During 2‐butene+ethylene metathesis with these materials at 450 °C, the propene yield is maximized (∼70 %) at a certain metal composition (∼20 wt% W and ∼1 wt% Nb), significantly surpassing those reported with an industrial WO 3 /SiO 2 catalyst. The enhanced propene yield is attributed to better dispersion of W species on the catalyst surface and the formation of new active site precursors (O=) 2 W(O−Si)(O−Nb), as confirmed by XRD, TEM, H 2 ‐TPR, XPS, EXAFS, and ToF‐SIMS techniques. Complementary DFT calculations reveal a positive correlation between the O=W=O bond angle and the propene yield. We therefore speculate that the −O−Nb moiety tunes the electronic environment around the W atom and increases the propene yield.