Extended Data Fig. 1: Catalyst characterization.
From: Promoting active site renewal in heterogeneous olefin metathesis catalysts
a, Transmission FTIR spectra of 3%SOMC (red), grafted precursor complex (pink), and SiO2–700 (blue). b, Tauc plot of 3%SOMC. The edge energy of 4.25 eV demonstrates that the catalyst is dominated by isolated WOx sites33,59. c, Raman spectra of 3%SOMC and SiO2–700 under different environments. The in-situ dehydrated sample was heated to 450 °C (1 °C/min) for 2 h and cooled to room temperature under flowing 50 mL/min purified air. The Raman spectrum for in-situ dehydrated 3%SOMC (yellow) was dominated by strong fluorescence, and no clear Raman features could be identified. The absence of peaks at 715 and 805 cm−1 in the Raman spectrum for ambient 3%SOMC (red) indicates a lack of WO3 crystallites on the catalyst33, and the peak at 960 cm−1 is attributed to WOx under ambient conditions33. The peak at 1100 cm−1 in the SiO2–700 spectrum (blue) is due to Si-O vibration60. Vertical offsets were applied for clarity. d, Tauc plot of 3% WOx/SiO2 (IWI). The edge energy of 4.11 eV demonstrates that the catalyst is dominated by isolated WOx sites33,59. e, Raman spectra of 3% WOx/SiO2 IWI (3% W IWI) catalyst (red) and SiO2 support (blue) under ambient conditions. As before, the absence of peaks at 715 and 805 cm−1 in the Raman spectrum indicates a lack of WO3 crystallites on the catalyst33. The region from 900 to 1200 cm−1 is dominated by strong Raman features attributable to Si-OH (ca. 970 cm−1) and Si-O vibrations (ca. 1100 cm−1)60. The subtle differences between the Raman spectra of the catalyst and support (close-up in inset) could be due to the isolated surface WOx species on the 3% WOx/SiO2 IWI catalyst33. Vertical offsets were applied for clarity.
