Preparation of composite TiO2-zeolite sheets using a papermaking technique and their application to environmental improvement -: Part II -: Effect of zeolite coexisting in the composite sheet on NOx removal

Sheets with a photocatalytic action were prepared using a papermaking technique. These sheets included single TiO2-sheet (Ti) and composite TiO2 sheets with A type zeolite (Ti-ZeA) and Y type zeolite (Ti-ZeY). A sheet (ZeA-Ti sol) containing A type zeolite treated with TiO2 sol was also prepared. Nitrogen monoxide (NO) was photocatalytically decomposed continuously when these sheets were used under UV irradiation. The subsequent photooxidation of NO to NO2 and of NO2 to HNO3 was observed. The NOx removal efficiencies of the sheets increased in the following order; Ti-ZeY< Ti< Ti-ZeA< ZeA-Ti sol. The reaction mechanism is discussed on the basis of the combined effects of the photocatalytic ability of TiO2 and the function of zeolites to adsorb NO and retain the products. (C) 2003 Kluwer Academic Publishers.