| abstract |
PCT No. PCT/JP90/01394 Sec. 371 Date Jul. 19, 1991 Sec. 102(e) Date Jul. 19, 1991 PCT Filed Oct. 30, 1990 PCT Pub. No. WO91/06508 PCT Pub. Date May 16, 1991.The present invention relates to a catalytic composition effective for removing harmful materials such as NOx, CO, HC, etc. causing photochemical smog, contained in a combustion waste gas exhausted from industrial plants, cars, etc. and has been developed based on finding that the crystalline silicate having the specified composition and crystalline structure and having been subjected to ion-exchange with copper has not only a very high activity as a catalyst of catalytically decomposing NO, but also a high selectivity for the conversion of NO into N2 and exhibits a stable activity even in the presence of oxygen and SOx, and when using this catalyst, NOx, CO and HC are decreased near the theoretical air fuel ratio and in a range of higher than the theoretical air fuel ratio, i.e. in the presence of oxygen. The catalyst consisting of the crystalline silicate in which copper is incorporated according to the present invention can effectively be used as a catalyst for decomposing NOx in a waste gas into N2 and O2, and in particular, NOx, CO and HC contained in a waste gas can effectively be decreased by the use of the catalyst. |