(192b) Oxidation of NOx over Carbon Nanotube-TiO2 Photocatalysts | AIChE

(192b) Oxidation of NOx over Carbon Nanotube-TiO2 Photocatalysts

Authors 

Everhart, B. - Presenter, Kansas State University
McAuley, B., Kansas State University
Hawkins, D., Kansas State University
Ortiz, D., Kansas State University
Amama, P. B., Kansas State University
Nitrogen oxides (NOx) are common compounds that can have detrimental environmental effects, originating from combustion reactions, which result in high amounts of nitrogen oxide (NO) and relatively lower amounts of nitrogen dioxide (NO2), the most common forms of NOx. In order to reduce concentrations of NOx in the air, heterogeneous photocatalysis conducted with semiconductors has been studied as an effective method for NOx abatement. Titanium dioxide (TiO2) is an attractive semiconductor used in photocatalysis. The large band gap of TiO2 limits viable photons to the UV spectra, resulting in a large influx of lower energy photons that cannot be used to initiate a photocatalytic reaction. TiO2 can be coupled with multiwalled carbon nanotubes (MWCNTs) to create a metallic-semiconductor heterojunction, increasing electron-hole recombination time, improving the pollution abatement by increasing the fraction of incident photons that partake in photocatalysis. In this work we evaluate P25 against a novel TiO2-MWCNT composite synthesized via a modified sol-gel method for its ability to completely degrage NOx in a laminar-flow reactor at different concentrations and humidity levels. We have utilized the “De-NOx index” to measure the photonic efficiency during NOx abatement, indicating the ability of a photocatalytic material to completely degrade NO to nitrates. This work illustrates the superior performance of MWCNT-TiO2 photocatalysts in photocatalytic oxidation of NOx under continuous flow. The MWCNT-TiO2 composite shows significantly increased photonic efficiency compared to P25, especially at humidity levels representative of outdoor conditions.