Water Tolerance of HC-SCR Catalysts

The NO removal activity of Cu-MOR-48 in the presence and absence of H2O was completely reversible. The reversibility of NO conversion has also been 

Among Co-FER, -MOR, -BEA and -MFI zeolites for NO reduction using CH4, the most desirable catalyst for the CH4-SCR reaction, if only their peak deNOx conversion is considered, has been shown to be a Co-FER within the reaction temperature range from 400 to 450 C, where an NOx reduction efficiency greater than 80% has been observed. Such a narrow temperature window in the present SCR reaction is quite common for Co-zeolite catalysts, while 

Sum of each exchange percentage value for both Pd and Co (Pd/Al = 0.18 and Co/Al = 0.20). Prepared by a chemical vapor deposition technique. 

4 Other Metal-Exchanged Zeolites. Nitrogen oxides have been selectively reduced by HCs over zeolite catalyst exchanged with other metal ions including Pd, Pt, Rh, In, Mn, Ga and Ce, besides Fe, Cu and Co. Pd-zeolites ° ° were most frequently investigated in this catalyst group. 

Pt-zeolite catalysts were also employed for the selective reduction of NO by HCs and were very active at lower reaction temperatures compared to Fe-, Cu- and Co-zeolites, but little, if any, literature was found for the Pt-exchanged zeolite catalysts deahng with the water tolerance. Iwamoto and coworkers conducted a comparative investigation of Pt- and Cu-MFI and Fe-MOR for their performance in NO reduction by C2H4. Pt-MFI-97 was found to be more active than the other two metal-exchanged zeolite catalysts at low temperatures and its activity for NO conversion at 200 C is hardly alfected by the addition of 8.6% H2O into the feed gas stream (Table 6), whereas the conversion of N2O formed during the course of the reaction slightly decreases by less than 10 /o. In 

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