Effect of water vapor over Pd-Co/SZ catalyst for the NO selective reduction by methane

The selective catalytic reduction (SCR) of NO by CH4 in the presence of excess O2 has been studied on Pd-Co, Pd and Co catalysts supported on sulfated zirconia (SZ) and activated in reaction mixture at 700 °C. After the addition of Co on Pd/SZ, an promoting effect on the catalytic activity was achieved, especially on 0.2%Pd-2%Co/SZ, which showed the maximum NO conversion higher 60% at 500 °C and 31,000 h−1. The bimetallic catalyst presented practical activity in the presence of water vapor. Stable NOx conversion was obtained for over 50 h in the presence of 6% water vapor. In order to correlate the catalysts composition with their activity, they were characterized by X-ray diffraction (XRD), diffuse reflectance spectroscopy (DRS) and temperature programmed reduction (TPR) techniques.