Browse Publications Technical Papers 2018-01-1256

Improvement of CO Oxidation Performance by Controlling Pd State in DOC 2018-01-1256

Diesel oxidation catalysts (DOCs) combining the functions of Pd and Pt-Pd alloys have been used in practice to satisfy the strict exhaust emission regulations that have been specified for passenger cars in recent years. Pd is an indispensable component in DOCs because it exhibits superior oxidation activity for CO and HC. To reduce the amount of precious metal used and to improve robustness, it is important to control the electronic state and gas adsorption characteristics of Pd and PdOx during catalytic reactions.In this study, by investigating the CO adsorption behavior of Pd, it was observed that Pd supported on a CeO2/ZrO2 mixed-oxide material (CZ) showed a preferable CO adsorption state and better CO light-off performance. Pd in Pd/CZ became metallic with increasing reaction time, and the CO oxidation performance of Pd/CZ decreased. This change in activity was correlated with CO adsorption on Pd changing from linear-type to bridge-type adsorption. In order to suppress this performance deterioration, a small amount of an additional electron promoter was placed near the Pd particles; this changed the CO adsorption state on Pd to a linear type that is preferable for CO oxidation activity. In addition, it is known that alloying Pd with Pt suppresses Pt sintering. The Pt -Pd alloying mechanism was studied using Extended X-ray Adsorption Fine Structure (EXAFS) spectroscopy. Furthermore, the correlation between the degree of alloying of Pt and Pd and the CO oxidation activity was investigated.


Subscribers can view annotate, and download all of SAE's content. Learn More »


Members save up to 16% off list price.
Login to see discount.
Special Offer: Download multiple Technical Papers each year? TechSelect is a cost-effective subscription option to select and download 12-100 full-text Technical Papers per year. Find more information here.
We also recommend:

Reactor System with Diesel Injection Capability for DOC Evaluations


View Details


CFD Investigation of the Impact of Electrical Heating on the Light-off of a Diesel Oxidation Catalyst


View Details


A One-Dimensional Model for Square and Octo-Square Asymmetric Particulate Filters with Correct Description of the Channel and Wall Geometry


View Details