Selective catalytic reduction of NO with NH3 over CeO2–ZrO2–WO3 catalysts prepared by different methods

Abstract

The selective catalytic reduction (SCR) of NO by NH3 has been investigated over the CeO2–ZrO2–WO3 (CZW) catalysts prepared by hydrothermal synthesis, incipient impregnation, co-precipitation and sol–gel methods. The results indicate that the CZW catalyst prepared by hydrothermal method shows the best SCR activity, and more than 90% NO conversion is obtained at 195–450°C with a gas hourly space velocity of 50,000h−1. The samples are characterized by XRD, N2 adsorption–desorption, SEM, EDS, XPS, H2-TPR, NH3-TPD and Pyridine-IR techniques. The results imply that the superior SCR activity of CZW catalyst is contributed to the excellent redox property, strong acidity and highest content of chemisorbed oxygen species. Furthermore, the larger surface area and greater total pore volume improve the redox ability and enhance NO conversion at low temperature, while the co-existence of Lewis and Brønsted acid sites enhance the SCR activity at high temperature.