Monolith Ce0.65Zr0.35O2-based catalysts for selective catalytic reduction of NOx with NH3

• Monolith catalyst WO3/Ce0.65Zr0.35O2 has a high NH3-SCR activity.
• It has an excellent aging-resistance.
• It has a good SO2 tolerance and ability to fit the high GHSV.
• WO3/Ce0.65Zr0.35O2 has the strongest oxidation property.
• The addition of Fe or W improves the acidity of the catalyst.

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 °C and has the highest NOx conversion of 96% at 350 °C. The reaction window of 80% NOx conversion is in the temperature range of 241–457 °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.

Monolith catalyst WO3/Ce0.65Zr0.35O2 has a high NH3-SCR activity. It has an excellent aging-resistance, good SO2 tolerance and good ability to fit the high GHSV.Figure optionsDownload high-quality image (193 K)Download as PowerPoint slide