Reduction kinetics of zeolite-hosted mono- and polynuclear titanium oxide species followed by UV/vis diffuse reflectance spectroscopy: influence of location and coordination

The kinetics of the reduction of zeolite-hosted mononuclear Ti(VI)Ox species followed by ultraviolet/vis diffuse reflection spectroscopy were investigated. Results showed that the reduction kinetics can be fitted if a Ti site exists at the surface of the zeolite NaY crystals and two sites in the void structure. The reduction rates for various Ti(VI)Ox species were found to increase with an increase in the excitation energy of the O to Ti charge transfer and decreases with an increase in the nuclearity of TiO clusters.