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.
Bibliographical noteFunding Information:
Acknowledgement This work is part of the ‘‘Development of Particle Zero Emission Technology for Future Vehicles’’ program funded by the Ministry of Knowledge Economy of Korea and we are grateful for its financial support.
- Pd/TiO /AlO
- Post-Euro IV
- Selective catalytic reduction (SCR)
ASJC Scopus subject areas
- General Chemistry