Au/TiO2@SBA-15 nanocomposite catalysts for the direct propylene epoxidation with O2 and H2 mixtures

A nanostructured Au/TiO2@SBA-15 catalyst has been prepared and applied in propylene epoxidation with a mixture of O2/H2. The mesopores of SBA-15 were first deactivated by grafting of hydrophobic groups. Titanium was then selectively grafted in the micropores of SBA-15 by reaction with titanium isopropoxide followed by calcination and deposition of Au nanoparticles. The nanocomposite catalysts exhibited relatively stable propylene oxide (PO) production with small amounts of propanal and acetone byproducts. A catalyst prepared by grafting with trimethylsilyl groups, a Ti/Si ratio of 0.05 and very small Au nanoparticles (