Passive NOx reduction with CO using Pd/TiO2/Al 2O3 + WGSR catalysts under simulated post-euro IV diesel exhaust conditions

Yoon Ki Hong, Dae Won Lee, Young Chul Ko, Li Yinghua, Hyun Sik Han, Kwan Young Lee

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12 Citations (Scopus)


This study deals with diesel DeNOx catalysis by physically mixed Pd/TiO2/Al2O3 and water-gas-shift-reaction (WGSR) catalysts under CO-rich conditions at a CO/NOx ratio of 16. In the post-Euro IV era, many diesel engines are expected to produce CO-rich exhaust emissions due to the trend toward emission regulation and limitations in related technologies. Under these circumstances, the passive DeNOx strategy utilizing CO as a single reductant can be considered appropriate. The Pd/TiO2/Al2O3 catalyst is well known for its high DeNOx performance when CO and H2 are available as NOx reductants. However, when CO is used as a single reductant, the catalyst shows poor DeNOx activity, even if the CO concentration is exceptionally high (CO/NOx = 16). In this study, the DeNOx activity of Pd/TiO2/Al2O3 was noticeably improved by physically mixing it with a proper WGSR catalyst (Cu/ZnO/Al 2O3), which is capable of producing H2 and feeding it to Pd/TiO2/Al2O3 successfully even in the presence of O2. The NOx conversion exceeded 70% at 400-450 °C using a Pd/TiO2/Al2O3 + Cu/ZnO/Al2O3 catalyst mixture at a weight ratio of 33:67. The reaction gas consisted of 500 ppm NO, 8000 ppm CO, 8 vol.% O2, 5 vol.% CO2 and 10 vol.% H2O and w/f was 0.1 g s/cm 3.

Original languageEnglish
Pages (from-to)106-115
Number of pages10
JournalCatalysis Letters
Issue number1-2
Publication statusPublished - 2010 May


  • Cu/ZnO/AlO
  • DeNO
  • Pd/TiO /AlO
  • Post-Euro IV
  • Selective catalytic reduction (SCR)

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)


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