Acceleration of VOC's vapor photocatalytic oxidation over TiO2 by the implementation of corona discharge and UVC radiation
Heterogeneous photocatalytic oxidation (PCO) over titanium dioxide (TO2) is one of the environmentally friendly methods of removing molecular impurities from the air, e.g., volatile organic compounds (VOCs). This method provides the complete mineralization of pollutants under ambient conditions into safe products (CO2, H2O, mineral acids). Therefore, PCO is considered as one of the most promising methods of air purification. However, this method has some limitations. A fundamental limitation of any pho-toinduced process is the limited number of light quanta. In order to increase the rate of such processes, researchers try to accelerate the oxidation processes by conducting a number of stages without the increase of light quanta number. Among others, a number of approaches are in saturation of the treated medium with high-reactivity particles, for example, ozone. This can be achieved by pretreating the gas mixture with a discharge plasma or treatment by UVC-light (100-280 nm). This work compares these two methods of ozone generation before the photocatalytic oxidation stage to identify the preferable method in practice. For controlling the ozone emission, an additional sample of the catalyst MnO2/TiO2 was placed into the combined purification system because it is capable of decomposing the ozone and further oxidizing organic impurities. The paper describes the influence of the PCO combination conditions on the rate of acetone vapor oxidation, their removal rate, and the accumulation of ozone as a byproduct of the process in an oxygen-containing atmosphere. It is shown that pre-treatment of the gas mixture before the photocatalytic stage contributes to the acceleration of the vapor oxidation processes. It is established that use of the ozone decomposition catalytic layer provides an additional acceleration of the observed oxidation process. Results obtained for the different values of the corona discharge current are given. They demonstrate the absence of direct proportionality in the effect of accelerating the oxidation process on the discharge current. The results show the acceleration of photocatalytic oxidation of acetone vapor over TiO2 due to the pretreatment of the gas medium by corona discharge plasma and catalytic aftertreatment on the MnO2/TiO2 layer. The obtained oxidation rate is 70% higher than the initial rates for a single photocatalytic oxidation, while the ozone concentration during the substrate oxidation process did not surpass the TLV level.
Keywords
фотокатализ,
окисление,
летучие органические соединения,
диоксид титана,
оксид марганца,
озон,
разложение озона,
коронный разряд,
фотолиз,
photocatalysis,
oxidation,
volatile organic compounds,
titanium dioxide,
manganese oxide,
ozone,
ozone decomposition,
corona discharge,
photolysisAuthors
| Lyulyukin Mikhail N. | Boreskov Institute of Catalysis, Siberian Branch of the Russian Academy of Sciences | lyulyukin@catalysis.ru |
| Gusachenko Egor A. | Boreskov Institute of Catalysis, Siberian Branch of the Russian Academy of Sciences | gusechenko@catalysis.ru |
| Kozlov Denis V. | Boreskov Institute of Catalysis, Siberian Branch of the Russian Academy of Sciences | kdv@catalysis.ru |
Всего: 3
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