Synthesis of CeOx/ γ-Al2O3 catalyst for the NH3-SCR of Nox

Cerium oxide catalysts (CeOx) supported on γ-Al2O3 for high temperature (T=200-400 ◦C) selective catalytic reduction (SCR) of nitrogen oxides (NOx) with NH3 in the presence of excess O2 were prepared by a facile impregnation method. Firstly, the support was prepared by a co-precipitation technique. These catalysts were characterized by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and H2-temperature Programmed reduction (H2-TPR) methods. The effects of reaction temperature and CeOx loading were investigated on NOx conversion and selectivity to N2, as a desired product. SEM image of the support showed a spherical and uniform morphology of the alumina with nanometric particles. Under the reaction conditions of 300 ◦C, 1 bar, NO=NH3=900 ppm, O2=5 vol%, GHSV=30,000 h−1 and 14 wt% CeOx, NOx conversion and N2 selectivity were 95% and 97%, respectively. XRD pattern and H2-TPR of the best catalyst (14 wt% CeOx) showed the presence of cerium oxide in form of CeO2 as a dominate phase, which is high reactive in NH3-SCR of NOx.

Keywords:

γ-Al2O3 , CeO2 , NOx , and NH3-SCR