Strontium-doped perovskites rival platinum catalysts for treating NOx in simulated diesel exhaust

Abstract

The high cost and poor thermal durability of current lean nitrogen oxides (NOx) aftertreatment catalysts are two of the major barriers to widespread adoption of highly fuel-efficient diesel engines. We demonstrated the use of strontium-doped perovskite oxides as efficient platinum substitutes in diesel oxidation (DOC) and lean NOx trap (LNT) catalysts. The lanthanum-based perovskite catalysts coated on monolith substrates showed excellent activities for the NO oxidation reaction, a critical step that demands heavy usage of platinum in a current diesel aftertreatment system. Under realistic conditions, La(1-x)SrxCoO3 catalysts achieved higher NO-to-NO2 conversions than a commercial platinum-based DOC catalyst. Similarly, a La(0.9)Sr(0.1)MnO3-based LNT catalyst achieved NOx reduction performance comparable to that of a commercial platinum-based counterpart. The results show promise for a considerably lower-cost diesel exhaust treatment system.