Nitrogen oxide-reducing catalyst and process for reducing nitrogen oxides in exhaust gas

摘要

PCT No. PCT/JP96/00978 Sec. 371 Date Dec. 11, 1996 Sec. 102(e) Date Dec. 11, 1996 PCT Filed Apr. 10, 1996 PCT Pub. No. WO96/33004 PCT Pub. Date Oct. 24, 1996The present invention provides a NOx reducing catalyst comprising BEA zeolite which is ion-exchanged with Co to have a Co/Al ratio between 0.2 and 0.6 and is loaded with at least one metal selected from among Ca, Sr, Ba, La, Mn, Ag, In, and Ni. The present invention also provides a NOx reduction process comprising the use of the catalyst of the present invention. The catalyst of this invention provides high activity, high NOx reduction selectivity and durability at low temperature in an actual exhaust gas containing water vapor and other substances disturbing catalytic activity even at low temperature and at low NOx and hydrocarbon concentration.