HIGHLY SELECTIVE REDUCTION OF NO IN EXCESS OXYGEN THROUGH THE INTERMEDIATE ADDITION OF REDUCTANT BETWEEN OXIDATION AND REDUCTION CATALYSTS

Intermediate addition of reductant (named an IAR method) into a NO+O-2 stream between an oxidation catalyst of NO to NO, and a reduction cat alyst of NOx to N-2 has been evidenced to be a very effective method t o selectively reduce NO to N, in the presence of excess oxygen. Here P I-MFI has been employed as an oxidation catalyst, Na-, Mg-, Ca-, Ba-, Zn- and In-MFI have been examined as the reduction catalysts and the r eductant was ethene. The combination of Pt-and Zn-MFI was the most eff ective. The efficiency of ethene, namely the molar ratio of the amount of NO reduced to that of ethene consumed, reached 1.9 and was much hi gher than 1.4 of conventional reduction on Cu-MFI.