Strontium-Doped Perovskites Rival Platinum Catalysts for Treating NOx in Simulated Diesel Exhaust

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Science  26 Mar 2010:
Vol. 327, Issue 5973, pp. 1624-1627
DOI: 10.1126/science.1184087

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Platinum-Free Diesel

The efficiency advantages inherent in diesel-based combustion engines are counterbalanced by the production of pollutants such as nitrogen oxides (NOx). Currently, expensive precious metals, such as platinum, are required to remove these pollutants. Kim et al. (p. 1624; see the Perspective by Parks) show that a strontium-doped perovskite catalyst, prepared from more abundant (and cheaper) elements, may help to lower the cost of NOx treatments and thus ultimately make diesel a more cost-effective automotive fuel. Under conditions realistically simulating exhaust streams, the catalyst rivaled platinum in accelerating NOx decomposition.


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, La1-xSrxCoO3 catalysts achieved higher NO-to-NO2 conversions than a commercial platinum-based DOC catalyst. Similarly, a La0.9Sr0.1MnO3-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.

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