Atmospheric NOx Reduction by Photocatalytic Paints (Industrial Technology Research Institute, MITI/Okitsumo) 1997

Atmospheric NOx Reduction by Photocatalytic Paints (Industrial Technology Research Institute, MITI/Okitsumo) 1997

Photocatalytic NOx reduction paint emerged as an innovative technology in the fight against urban air pollution in the late 1990s. The paint, developed jointly by MITI's Industrial Technology Research Institute and Okitsumo, has a mechanism whereby NOx adsorbed on the paint film surface under sunlight is oxidized and converted to nitric acid, which is then washed away by rain, thereby regenerating it.

Experiments have confirmed that a 200 square centimeter coating film can remove approximately 80% of NOx 1 ppm for 24 hours continuously. At a time when automobile exhaust emissions were becoming increasingly serious, the possibility of applying the coating to building exterior walls and road structures attracted attention, and local governments began to introduce the coating on a trial basis. At the same time, however, there are issues that need to be addressed in order to implement the technology, such as weather resistance, the effects of stains, and response to concentration fluctuations.

Photocatalytic technology was later expanded to multiple areas, including exterior materials, pavement materials, and air purifiers, and established as a fundamental technology for urban environmental purification.