Preparation of highly dispersed CuO catalysts on oxide supports for de-NOx reactions

CuO based catalysts dispersed on silica–alumina supports at low (0.56 wt.%) and high (13 wt.%) Al2O3 content were prepared by adsorption method with or without ultrasound treatment. The catalysts obtained were studied in their bulk (atomic absorption, X-ray diffraction, temperature programmed reduction) and surface (N2 adsorption and X-ray photoelectron spectroscopy) properties. Significant differences between the series of catalysts prepared over the two supports in terms of size of the CuO aggregates and of their redox properties were evidenced. All the catalysts were tested in the selective catalytic reduction of NOx using C2H4 as reducing species (HC-SCR process) in highly oxidant atmosphere. The CuO-catalysts prepared using ultrasounds were the most active. Moreover, they displayed a peculiar activity being able to activate NO both by reducing it to N2, in larger extent, and by oxidizing it to NO2.