Strontium-Doped Perovskites Rival Platinum Catalysts for Treating NO x in Simulated Diesel Exhaust

Abstract

The high cost and poor thermal durability of current lean nitrogen oxides (NO_x) 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 NO_x 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-xSr_xCoO₃ catalysts achieved higher NO-to-NO₂ conversions than a commercial platinum-based DOC catalyst. Similarly, a La_0.9Sr_0.1MnO₃-based LNT catalyst achieved NO_x reduction performance comparable to that of a commercial platinum-based counterpart. The results show promise for a considerably lower-cost diesel exhaust treatment system.