Ternary mixed-oxide synergy effects of nano TiO2-FexOy-MOk (M = Mn, Ce, Co) on α-pinene catalytic oxidation process assisted by nonthermal plasma

Abstract

Biomass fuel from plant waste is an important substitute for fossil fuels. The odorous volatile organic compounds (VOCs) is released during the drying process of biomass, which causes harm to the ecological environment and human health. The α-pinene is a typical odorous VOC generating during plant waste drying. Ternary nanocatalyst composed of TiO2, FexOy and MOk (M = Mn, Co, Ce) was manufactured by ultrasonic assisted hydrothermal process. The α-pinene catalytic oxidation property of ternary nanocatalysts were investigate in a dielectric barrier discharge reactor assisted by nonthermal plasma. The pore structure parameters of ternary nanocatalysts were observed qualitatively and analyzed quantitatively by transmission electron microscopy (TEM) and N2 adsorption test, respectively. The phase composition and active element valence of these three kinds nanocatalysts were analyzed and compared by X-ray diffraction (XRD) and X-ray Photoelectron spectroscopy (XPS). The test data showed TiO2-FexOy-CoOk ternary nanocatalyst had more complete microporous and mesoporous pore structure, better element dispersion and stronger redox performance. Meanwhile, TiO2-FexOy-CoOk sample had the best performance with α-pinene catalytic conversion achieving 83.3% and CO2 selectivity higher than 90% at specific energy density (SED) of 620 J·l−1, which was almost half of the energy consumption of single non-thermal plasma catalytic reaction during the nonthermal plasma-catalyst (NTP-C) synergistic catalytic activity experiments. At the same time, the ternary nanocatalysts could obviously reduce the generation concentration of O3 and NOx in the process of α-pinene catalytic oxidation. The synergy effect between TiO2, FexOy and CoOk was better than that of TiO2, FexOy and CeOk or MnOk. It could be expected as an effective method to improve the redox performance of ternary nanocatalysts by optimizing the microstructure and elemental composition, which would also be a promising way to enhance odorous VOCs catalytic oxidation efficiency and reduce the energy consumption in the NTP-C synergistic catalytic system.