INVESTIGATION OF THE TRANSIENT BEHAVIORS OF PHOTOCATALYTIC NO OXIDATION OVER TiO2

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2022-1-12

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Ernam, Selin

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The objective of this thesis is to investigate the bottlenecks of photocatalytic NO oxidation reaction. This reaction is used as a standard diagnostic tool for photocatalytic activity according to the well defined protocols described by the ISO Standard (22197-1-2007). One of the problems with photocatalytic NO oxidation is the transient period of NO conversion between the beginning of illumination and the time the conversions reach a steady state. The nature of this behavior depends strongly on parameters such as the illumination intensity and the concentration of the reactants, in particular the moisture content. In order to reveal the effect of the illumination intensity and the moisture content, devices with sensors and microcontroller boards were built. Controlled experiments revealed that at higher light intensities, the reaction starts with a very high conversion and need longer times to reach steady state, at a lower conversion value. In contrast, experiments with low light intensities reach this steady conversion level almost immediately after the reaction starts. Using the light intensity measurement device built for this purpose, a relationship was obtained between the steady state reactant conversion and illumination intensity (at 365 nm) as follows: X=c+aI^b where a=0.1809, b=0.3733, c=0.7265. Furthermore, the effect of water injections to the system was also investigated using a relative humidity measurement device specifically built for this purpose. The water injection transient data collected in this study revealed the qualitative nature of the interactions. The system can be effective at collecting data and can be used to determine a reaction model.

Subject Keywords

Water Injection, Photocatalysis, Illumination Intensity,, NO Oxidation, TiO2

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https://hdl.handle.net/11511/96374

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Graduate School of Natural and Applied Sciences, Thesis

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Citation Formats

S. Ernam, “INVESTIGATION OF THE TRANSIENT BEHAVIORS OF PHOTOCATALYTIC NO OXIDATION OVER TiO2,” M.S. - Master of Science, Middle East Technical University, 2022.