NO reduction by CH_4 in the presence of excess O_2 over Pd/sulfated alumina catalysts

摘要

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/gamma-Al_2O_3 showed only a low activity for the SCR of NO with methane but high activity for combustion by-reaction.After pretreating the gamma-Al_2O_3 with H_2SO_4,a remarkably promoting effect on the catalytic activity was achieved.NH_3-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 gamma-Al_2O_3 with 2.5 M H_2SO_4.The activity of Pd/SA catalyst can be improved by increasing the surface area of the gamma-Al_2O_3 precursor.Moreover,the Pd/SA catalyst as prepared exhibited high catalytic performance in high space velocity and in the presence of SO_2.