TiO₂ nanotube-supported Cu as the catalyst for selective NO reduction with NH₃

Catalyst supports composed of titanate nanotubes were prepared from hydrothermal treatment on TiO₂ nanoparticles in NaOH followed by HCl washing. The nanotubes exhibited well-defined TiO₂ anatase phase after calcination at 400°C. The nanotube aggregates and other commercially available TiO₂ nanoparticles, all with surface areas >300 m ²/g, were impregnated with Cu and examined in selective catalytic reduction of NO with NH₃. In catalyst preparation, the nanotubes were found to be more thermally stable than nanoparticles, withstanding agglomeration at elevated temperatures. The Cu species supported on the nanotubes showed a higher catalytic activity than those supported on the nanoparticles. Analysis with temperature programmed reduction, X-ray photoelectron spectroscopy, and NO adsorption reflected that the layered-titanate feature of the tube wall was advantageous for even distribution of the Cu species, thus leading to the high-catalytic activity of the tubular Cu/TiO₂ catalyst.