Monolith Ce0.65Zr0.35O2-based catalysts for selective catalytic reduction of NO with NH3

The carrier material Ce0.65Zr0.35O2 was prepared by the co-precipitation method and a series of Ce0.65Zr0.35O2-based monolith catalysts containing W, Fe or Cu were prepared for selective catalytic reduction (SCR) of NOx with NH3. The catalysts were characterized by ammonia oxidation, N2 adsorption-desorption, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and NH3 temperature-programmed desorption (NH3-TPD). Catalytic activity tests reveal that catalyst WO3/Ce0.65Zr0.35O2 has the best catalytic activity and a good resistance to hydrothermal aging. It is light-off at 200 degrees C and has the highest NOx conversion of 96% at 350 degrees C. The reaction window of 80% NOx conversion is in the temperature range of 241-457 degrees C with a gas hourly space velocity (GHSV) of 30,000 h(-1). Moreover, it has a good SO2 tolerance and good ability to fit the high GHSV, which suggests that it has a good prospect for real application. Characterization experiments show that WO3/Ce0.65Zr0.35O2 has a weaker property of ammonia oxidation, a larger surface area, strong oxidation property with the highest binding energy of Ce, Zr and O, and the most surface medium-strength acid. These characteristics are the main factors that lead to the increased SCR activity. (C) 2014 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.