Au/γ-MnO2 catalyst for solvent-free toluene oxidation with oxygen

α-, δ-, and γ-MnO2 were synthesized by a redox method and Au/γ-MnO2 catalysts with different Au loadings (0.5%–3.0%) were synthesized by an in situ reduction method. The supports and catalysts were characterized by X-ray diffraction, scanning electron microscope, transmission electron microscopy (TEM), and N2 adsorption. TEM images showed that the Au particles were about 10 nm. The catalysts were used in solvent-free toluene oxidation with oxygen. The results showed that toluene conversion increased with increasing Au loading, which was ascribed to the increasing amount of Au particles and also the smaller Au particles. The Au loading gave a uniquely high selectivity to benzaldehyde. The Au/γ-MnO2 catalysts exhibited good reusability in liquid phase toluene oxidation.

Graphical AbstractWell dispersed Au/γ-MnO2 catalysts have been prepared by an in situ reduction method. They showed unique selectivity towards benzaldehyde in toluene oxidation.Figure optionsDownload full-size imageDownload as PowerPoint slide