Improved Photocatalysts for selective NOx-degradation

Highlight Project 2017 of Industrial collective Research (IGF)

The air contamination with nitrogen oxides and other harmful substances such as ozone, volatile organic compounds (VOCs) presents a serious problem nowadays. The main part of these emissions is generated by anthropogenic sources, i.e. human activities. The European Union introduced strict maximum permissible values by the guideline 2008/50/EG to improve the air quality. Different actions taken to achieve the target values but the maximum annual average value of 40 µg/m³ NO₂ is still frequently exceeded in most German cities. The active reduction independent of the source of the amount of harmful substances by photocatalysis is a new and promising approach for an improved air quality. NO and NO₂ can be oxidized to harmless nitrate on the surface of the photocatalyst when it is irradiated by sunlight. Afterwards, the formed nitrate will be washed off and removed by rainwater.

To this day, the quality of photocatalysts is only measured according to their potential to remove NO or total NO_x. There is no differentiation between the different species despite their vastly different risk potential. NO₂ is much more harmful compared to NO. If the NO₂ concentration is measured during a photocatalytic oxidation test, it becomes clear that the release of NO₂ is a critical problem. Additionally, the behavior of ozone in combination with photocatalysts is still unclear. In this project, we will explore the effect of co-catalysts on the selectivity of the reaction and the influence of ozone in the photocatalytic process will be clarified.

Das IGF-Vorhaben Nr. 1815210 der Forschungsvereinigung DECHEMA e.V., Theodor-Heuss-Allee 25, 60486 Frankfurt am Main wurde über die AiF im Rahmen des Programms zur Förderung der industriellen Gemeinschaftsforschung (IGF) vom Bundesministerium für Wirtschaft und Energie aufgrund eines Beschlusses des Deutschen Bundestages gefördert.