Studies On The Catalytic Combustion Performance Of Flame Spray Pyrolysis Synthesized Ti-based Nanocatalysts

The emissions of low-concentration combustible gases associated with energy harvesting and industrial applications threaten human health and environment.These pollutants mainly include CO,CH₄ and volatile organic compounds（VOCs）.To reach the goal of complete purification,catalytic combustion receives extensive attention.In this technology,exploration of scalable high-efficient catalysts is of great significance to remove the pollutants with a lower degradation temperature.Flame spray pyrolysis（FSP）is recognized as one novel synthesis route for nanoparticles with many preferable properties,which can contribute to the advanced preparation of supported catalysts and perovskite catalysts.Limited loading of active components on supports has been one obstacle to improve catalytic efficiency for supported catalysts.Here,we prepare highly active nanocatalysts CuO-TiO₂ via the one-step flame spray pyrolysis（FSP）method with different mass contents of CuO loaded on TiO₂（from 2～50 wt.%）.It aims to probe the dispersion behavior and catalytic performance.The particles show sphere structure with nanosized diameters at the range of 10-20 nm and they all possess large specific surface areas.A large amount of copper cations is embedded into the lattice of TiO₂,causing a crystal transformation from anatase to rutile.The catalysts are applied into the elimination of toluene with a typical concentration of 300 ppmv.8-20 wt.%CuO loaded TiO₂ exhibits total oxidation temperature of as low as 250°C in the absence of water vapor,which is mainly ascribed to the stably-existed highly-dispersed CuO and good redox properties.The reactivity and quantity of the highly-dispersed active sites contribute a synergistic effect on the overall performance,resulting in 20 wt.%CuO as the optimized mass ratio without vapor condition.Meanwhile,the highly-dispersed CuO can alleviate the degradation of activity under humidity,which results the optimal mass ratio as 8wt.%CuO under 10 vol.%water vapor.The stable crystal structures bring the opportunities of perovskites in catalytic combustion technology,but the highly demanding synthesis procedure still hinders the wide application.In this work,a series of nanostructured SrTi O₃ perovskites with B-site partial substitution by Co,Fe,and Mn are synthesized via flame spray pyrolysis in one step.The flame-made perovskite particles all exhibit high crystal purity and large specific surface area（～40 m²/g）.The prepared samples are tested in catalytic combustion of both lean CO and lean CH₄.The highest catalytic activity is achieved by Sr Ti_0.9Co_0.1O₃（～275°C and～658°C to attain 90%removal of CO and CH₄,respectively）,due to the formation of favorable oxygen vacancies and distinct oxygen mobility.Eventually,the long-term catalytic removal performance of Sr Ti_0.9Co_0.1O₃ towards a mixture of lean CO and CH₄ is evaluated in the presence of water vapor.The stable and nearly complete CO/CH₄ conversion attained during the operation indicates the flame-made perovskite can possess the remarkable durability and water resistance.