NO reduction by CH4 in the presence of excess O2 over Pd/sulfated alumina catalysts

Selective catalytic reduction (SCR) of nitric oxide with methane in the presence of excess oxygen has been studied for the first time on a series of Pd loaded sulfated alumina (SA) catalysts. Pd/γ-Al2O3 showed only a low activity for the SCR of NO with methane but high activity for combustion by-reaction. After pretreating the γ-Al2O3 with H2SO4, a remarkably promoting effect on the catalytic activity was achieved. NH3-TPD spectra of different catalysts demonstrated that the sulfation increased the acidity of support which is very important for the reduction of NO with methane over Pd catalysts. The Pd/sulfated alumina catalyst exhibited best catalytic activity when 0.1 wt.% Pd was loaded on sulfated alumina (SA) prepared by impregnating the γ-Al2O3 with 2.5 M H2SO4. The activity of Pd/SA catalyst can be improved by increasing the surface area of the γ-Al2O3 precursor. Moreover, the Pd/SA catalyst as prepared exhibited high catalytic performance in high space velocity and in the presence of SO2.