Major Diesel Oxydation Catalyst Breakthrough

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May 21, 2010 | 08:59 PM

gearloose1

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Major Diesel Oxydation Catalyst Breakthrough

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</td></tr></tbody></table> GM R&D Develops and Demonstrates Strontium-Doped Perovskite Catalysts Rivaling Platinum Catalysts for NOx Control in Diesel Exhaust; Lower Cost Could Be a Boost for Diesel

26 March 2010

<table style="font-size: 7pt; font-family: Geneva,Arial,Helvetica,sans-serif; margin-left: 5px;" align="right" border="0" cellpadding="0" cellspacing="0" width="150"><tbody><tr><td>

</td></tr> <tr><td align="center">NO<sub>x</sub> conversion profiles. Commercial LNT (black dashed line); La<sub>0.9</sub>Sr<sub>0.1</sub>MnO<sub>3</sub>-based LNT (green line); La<sub>0.9</sub>Sr<sub>0.1</sub>MnO<sub>3</sub>-based LNT after a S loading of 1 g liter<sup>–1</sup> catalyst (red line); and La<sub>0.9</sub>Sr<sub>0.1</sub>MnO<sub>3</sub>-based LNT after desulfation (blue line) as a function of temperature. Credit: Kim et al. Click to enlarge.</td></tr></tbody></table>Researchers from the General Motors Global Research and Development, Chemical Sciences and Materials Systems Lab have developed and demonstrated the use of strontium-doped perovskite oxides as efficient platinum substitutes in diesel oxidation (DOC) and lean NO<sub>x</sub> trap (LNT) catalysts. Their work may help to lower the cost of NO<sub>x</sub> treatments and thus ultimately make diesel a more cost-effective automotive fuel. A paper on the work was published in the 26 March issue of the journal Science.
One of the obstacles to the more widespread adoption of diesel engines—especially in the face of increasingly stringent emissions requirements—is the requirement for a lean NO<sub>x</sub> aftertreatment system. The aftertreatment system is a key contributor to the cost premium for diesel vehicles.
 A typical diesel aftertreatment system will include a diesel oxidation catalyst to oxidizes hydrocarbons, CO, and NO, followed by NO<sub>x</sub> reduction. The two leading technologies for NO<sub>x</sub> reduction in the oxygen-rich environment are ammonia selective catalytic reduction (SCR) and a lean NO<sub>x</sub> trap (LNT).

The catalyst developed by Kim et al. greatly reduces the amount of PGM in LNTs while still maintaining their effectiveness for NO<sub>x</sub> reduction from lean engines. This alternative technology will allow engineers greater flexibility as they work to develop better catalysts in a market where volatile PGM prices have made commercial introduction of fuel-efficient lean vehicles challenging. It is possible that these catalysts may allow lean-burn technology to be used with minimal added cost compared to conventional engines.

Resources

Chang Hwan Kim, Gongshin Qi, Kevin Dahlberg, Wei Li (2010) Strontium-Doped Perovskites Rival Platinum Catalysts for Treating NO<sub>x</sub> in Simulated Diesel Exhaust. Science Vol. 327. no. 5973, pp. 1624 - 1627 doi: 10.1126/science.1184087
James E. Parks, II (2010) Less Costly Catalysts for Controlling Engine Emissions. Science Vol. 327. no. 5973, pp. 1584 - 1585 doi: 10.1126/science.1187154

Green Car Congress: GM RD Develops and Demonstrates Strontium-Doped Perovskite Catalysts Rivaling Platinum Catalysts for NOx Control in Diesel Exhaust; Lower Cost Could Be a Boost for Diesel