The effect of TiO2 crystal phase on CH3Br catalytic combustion over Ru/TiO2 catalyst

Supported Ru catalysts over TiO 2 with various crystal phases were prepared, which involved rutile, anatase, and their mixed phase. And their catalytic activities for CH 3 Br complete oxidation were investigated. Results showed Ru/TiO 2-700-4 that TiO 2-700-4 is sourced from anatase TiO 2 calcined at 700 °C for 4 h is the most active catalyst among these catalysts. The content of rutile phase on the surface is lower than the bulk. Strong metal support interaction occurs owing to lower lattice mismatch between RuO 2 and rutile TiO 2 . It was further verified by H 2 -temperature programmed reduction, ultraviolet-Raman and transmission electron microscopy . Especially mixed-phase TiO 2 is more conductive to higher dispersion of RuO 2 than pure phase TiO 2 , which is easier to form epitaxial growth . The catalytic activity for CH 3 Br complete oxidation was not in exact accord with the dispersion of Ru. It is possibly attributed to the combination of arguably favorable physico-chemical properties of more Ru active sites, electron transfer , and appropriate surface acidity. At the low reaction temperature, more Ru active sites are beneficial for the total oxidation of CH 3 Br. With the increase of temperature, higher activity is prone to strong surface acidity and electron transfer, as was confirmed by X-ray photoelectron spectra and NH 3 -temperature programmed desorption analysis.