NO reduction by CH4 in the presence of excess O2 over Co/sulfated zirconia 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 non-noble metal (Co, Mn, In, Ni) catalysts supported on sulfated zirconia (SZ). Pure SZ showed only a low activity for the SCR of NO with methane. After loading Co, Mn, In and Ni on SZ, an obvious promoting effect on the catalytic activity was achieved. Especially for the 4 wt.% Co/SZ and the 4 wt.% Mn/SZ, over which the maximum NO conversions above 60% were reached. Moreover, the Co/SZ also exhibited good stability during a long-term test of 60 h. By comparing the activities of ZrO2, SZ, Co/ZrO2 and Co/SZ, it was found that sulfation of the support was essential for the generation of the Co sites that were active for the reduction of NO. The most attractive feature of the Co/SZ catalysts is that they are less sensitive to water and SO2 poisoning than the Co/HZSM-5 catalysts and exhibit higher reversibility after the removal of SO2.