Continuous hydrothermal flow syntheses of transition metal oxide doped Ce xTiO 2 nanopowders for catalytic oxidation of toluene

Abstract

A series of transition metal oxides doped Ce x TiO 2 samples were synthesized using a continuous hydrothermal flow synthesis (CHFS) method. The resultant samples were then investigated using a range of analytical methods, including XPS, X-ray powder diffraction, H 2-TPR, TEM and BET surface area measurements. Experimental results showed that the samples were highly crystalline with remarkably high surface areas (in the range of 200–300 m 2 g −1), which were ca. two-fold higher than those synthesized via more conventional routes. The Ce 0.05TiO 2 sample revealed a good catalytic performance in toluene oxidation, which was subsequently utilized for the optimization of transition metal oxide doping. After screening MnO x , CrO x and CuO x doping, it was found that they had all led to significant enhancements in the activity for toluene conversion, particularly for CuO x doped sample, which showed a superior performance ( T 90 = 200 °C) for toluene oxidation, comparable to some noble metal catalysts.