The mechanism of supported gold catalysts in the selective oxidation of propane with H2 and O2 is not clear. It is known that propene is selectively produced over Au/TiO2,1 while acetone and isopropanol are the main products over Au/TS-1.2, 3 The proposed mechanism3 recognized Ti-OOH as the reaction intermediate resulting from the migration of H2O2 formed on Au nanoparticles. It also proposed that propane could react with Ti-OOH and form Ti-isopropoxide species, which either undergoes oxidation to acetone or dehydration to propene due to the acid/base properties from different nuclearity of Ti. We have investigated the reaction pathways by following the dehydrogenation, dehydration, and oxidation of 2-propanol, as well as propene and acetone. Information about the reaction mechanism is generated by comparing the kinetics and product distributions of these reactions with those of propane. In addition, these reactions were also compared using Au catalysts decorated with Ti-oxo complexes of different nuclearity (one to four) and surface coverage (up to 3 monolayers of Ti-monomer). Results of characterization and catalysis with these Ti-modified Au catalysts in reactions of C3 reactant with a mixture of H2 and O2 are presented.
1 J. J. Bravo-Suárez, K. K. Bando, J. Lu, T. Fujitani and S. T. Oyama, J. Catal., 2008, 255, 114.
2 J. J. Bravo-Suarez, K. K. Bando, T. Fujitani and S. T. Oyama, J. Catal., 2008, 257, 32.
3 J. J. Bravo-Suarez, K. K. Bando, T. Akita, T. Fujitani, T. J. Fuhrer and S. T. Oyama, Chem. Commun., 2008, 3272.