Enhancement of catalytic activity by homo-dispersing S₂O₈^2--Fe₂O₃ nanoparticles on SBA-15 through ultrasonic adsorption

Mesoporous superacids S₂O₈^2--Fe₂O₃/SBA-15 (SFS) with active nanoparticles are prepared by ultrasonic adsorption method. This method is adopted to ensure a homo-dispersed nanoparticle active phase, large specific surface area and many acidic sites. Compared with bulk S₂O₈^2--Fe₂O₃, Brönsted acid catalysts and other reported catalysts, SFS with an Fe₂O₃ loading of 30% (SFS-30) exhibits an outstanding activity in the probe reaction of alcoholysis of styrene oxide by methanol with 100% yield. Moreover, SFS-30 also shows a more excellent catalytic performance than bulk S₂O₈^2--Fe₂O₃ towards the alcoholysis of other ROHs (R = C₂H₅-C₄H₉). Lewis and Brönsted acid sites on the SFS-30 surfaces are confirmed by pyridine adsorbed infrared spectra. The highly efficient catalytic activity of SFS-30 may be attributed to the synergistic effect from the nano-effect of S₂O₈^2--Fe₂O₃ nanoparticles and the mesostructure of SBA-15. Finally, SFS-30 shows a good catalytic reusability, providing an 84.1% yield after seven catalytic cycles.