Platinum-group-metal free catalytic washcoats for particulate exhaust gas filter applications

摘要

New Platinum Group Metal (PGM) free catalytic compositions comprising silver (Ag) stabilized ceria (CeO2) with Ag amount within the range of 5-90 mol.% facilitating soot oxidation during the regeneration of Diesel particulate filters (DPF), replacing (PGM) formulations are described. The catalysts have been studied by a TGA method on soot oxidation activity. They proved particularly useful as washcoat compositions for DPF as part of an automotive after-treatment system for elimination and/or minimizing of exhaust gas emissions, particularly for directly injected fuel engine vehicles. This was shown by testing full-size coated Diesel particulate filters. Among the formulations tested, the silver-stabilized ceria formulations e.g. can oxidize soot at 250-300 DEG C in the presence of NO2 and oxygen, they can oxidize diesel soot even in the presence of oxygen as the sole oxidizing agent at these temperatures. The regeneration abilities were comparable or better than Pt formulations with Pt loading of 100g/ft<3> (28.32 g Pt/m<3>). The balance point was achieved at 250-275 DEG C with complete soot oxidation at 325 DEG C.The levels of CO; NOx and HC emissions during regeneration were also comparable. New Platinum Group Metal (PGM) free catalytic compositions comprising silver (Ag) stabilized ceria (CeO2) with Ag amount within the range of 5-90 mol.% facilitating soot oxidation during the regeneration of Diesel particulate filters (DPF), replacing (PGM) formulations are described. The catalysts have been studied by a TGA method on soot oxidation activity. They proved particularly useful as washcoat compositions for DPF as part of an automotive after-treatment system for elimination and/or minimizing of exhaust gas emissions, particularly for directly injected fuel engine vehicles. This was shown by testing full-size coated Diesel particulate filters. Among the formulations tested, the silver-stabilized ceria formulations e.g. can oxidize soot at 250-300 DEG C in the presence of NO2 and oxygen, they can oxidize diesel soot even in the presence of oxygen as the sole oxidizing agent at these temperatures. The regeneration abilities were comparable or better than Pt formulations with Pt loading of 100g/ft<3> (28.32 g Pt/m<3>). The balance point was achieved at 250-275 DEG C with complete soot oxidation at 325 DEG C.The levels of CO; NOx and HC emissions during regeneration were also comparable.