ACTIVITY ENHANCEMENT OF AG MORDENITE CATALYSTS BY ADDITION OF PALLADIUM FOR THE REMOVAL OF NITROGEN-OXIDES FROM DIESEL-ENGINE EXHAUST-GAS/

Various Ag-Pd/mordenite catalysts were prepared on washcoated honeycom bs and tested in terms of NOx removal from diesel exhaust gas with (CH 3)(2)O as a reducing agent at a practical high level of space velocity . The activity was dependent upon the palladium loading. In terms of N Ox removal, the order of catalytic activity was Ag(3)/Pd(0.01)/mordeni te > Ag(3)/Pd(0.1)/mordenite > Ag(3)/mordenite catalyst > Ag(3)/Pd(1.0 )mordenite. It was found that a relatively small loading of palladium on Ag/mordenite catalysts led to a significant improvement in catalyti c activity over a wide range of temperatures. The properties of these catalysts were also investigated by the NH3 temperature programed deso rption (TPD) and BET method. It was found that Ag(3)/Pd(0.01)/mordenit e had a larger amount of acid sites. It was concluded that Ag/mordenit e catalyst with a small amount of palladium can effectively remove NOx over a wide range of temperatures using (CH3)(2)O as a reducing agent . (C) 1998 Elsevier Science B.V.