Passive NOx Reduction with CO Using Pd/TiO2/Al2O3 + WGSR Catalysts Under Simulated Post-Euro IV Diesel Exhaust Conditions

Abstract

This study deals with diesel DeNO x catalysis by physically mixed Pd/TiO 2 /Al 2 O 3 and water-gas-shiftreaction (WGSR) catalysts under CO-rich conditions at a CO/NO x 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 DeNO x strategy utilizing CO as a single reductant can be considered appropriate. The Pd/TiO 2 /Al 2 O 3 catalyst is well known for its high DeNO x performance when CO and H 2 are available as NO x reductants. However, when CO is used as a single reductant, the catalyst shows poor DeNO x activity, even if the CO concentration is exceptionally high (CO/NO x = 16). In this study, the DeNO x activity of Pd/TiO 2 /Al 2 O 3 was noticeably improved by physically mixing it with a proper WGSR catalyst (Cu/ZnO/Al 2 O 3 ), which is capable of producing H 2 and feeding it to Pd/TiO 2 /Al 2 O 3 successfully even in the presence of O 2 . The NO x conversion exceeded 70% at 400-450°C using a Pdcatalyst mixture at a weight ratio of 33:67. The reaction gas consisted of 500 ppm NO, 8000 ppm CO, 8 vol.% O 2 , 5 vol.% CO 2 and 10 vol.% H 2 O and w/f was 0.1 g s/cm 3 .

110th Anniversary: Recent Progress and Future Challenges in Selective Catalytic Reduction of NO by H2in the Presence of O2

“…Another promotional strategy was developed by Hong et al 101 via physically mixing a conventional SCR catalyst (Pd/ TiO 2 /Al 2 O 3 ) with a water−gas shift reaction (WGSR) catalyst (Cu/ZnO/Al 2 O 3 ). It was found that the SCR activity was remarkably improved at temperatures over 300 °C, and the optimal ratio of Pd/TiO 2 /Al 2 O 3 + Cu/ZnO/Al 2 O 3 was 33:67.…”

“…Another promotional strategy was developed by Hong et al . via physically mixing a conventional SCR catalyst (Pd/TiO 2 /Al 2 O 3 ) with a water–gas shift reaction (WGSR) catalyst (Cu/ZnO/Al 2 O 3 ).…”

Computational Fluid Dynamics Analysis of Flow and Combustion of a Diesel Engine

“…In addition, these emissions play a critical role in global warming and greenhouse effects. NOx also causes acid rain and destruction of the ozone layer [6][7][8]. Therefore, emission control is tremendously momentous in diesel engines [9][10][11][12].…”

Influence of Supports on Pd Catalysts for the Selective Catalytic Reduction of NOx with H2 and CO

“…Significant attention has been given to the development of selective catalytic reduction (SCR) of NO x using H 2 [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18], CO [19][20][21], or a mixture of H 2 /CO [22][23][24][25][26][27][28][29][30][31][32][33] as reductant. Catalysts using H 2 and/or CO have the advantage of lowtemperature DeNO x activity, and the reductants could be produced using an on-board fuel reformer, thus eliminating the need of carrying any additional reductant.…”