Compatibility optimization and de-NO_x influencing factors of Ce-Sn-W-O_x catalyst

Series of Ce-Sn-W-O_x complex oxides were prepared by blending thermal decomposition and tested for selective catalytic reduction (SCR) of NO with NH₃. Ce-Sn-W-O_x compatibility were designed and optimized by orthogonal experiments, and characterized by scanning electron microscope (ESEM), transmission electron microscope (TEM) and X-ray diffraction (XRD) to establish the optimal compatibility and its structural morphology. Experimental results showed that the Ce-Sn-W-O_x with the Ce/Sn/W molar ratio of 1∶0.8∶0.6, supported on cordierite ceramics with particle sizes of 5~8 mm, exhibited the best catalytic activity for NH₃-SCR of NO. The CeSn_0.8 W_0.6 O_x/CC was able to obtain more than 94% NO conversions in the active temperature range of 252~426℃ under the gas hourly space velocity (GHSV) of 7 200 h^-1. Moreover, effects of GHSV, water vapor (H₂O) and SO₂ on catalytic activity for NH₃-SCR of NO over CeSn_0.8 W_0.6 O_x/CC were studied. Results showed that the GHSV had little influence on catalytic activity when the GHSV was less than 10 000 h^-1, furthermore, the catalytic activity almost not changed in presence of 5% H₂O, and the catalytic activity slightly decreased in presence of 429 mg/m³ SO₂. The catalytic activity decreased to 85.33% in presence of 5% H₂O and 429 mg/m³ SO₂, while the catalytic activity was able to obviously recover after moving away the SO₂ and H₂O.