S Tolerant Pt-Pd Based Diesel Oxidation Catalyst for LDD Euro 4 Application Johnson Matthey Japan Incorporated

Format:

Conference/Event

Author/Creator:

Sumiya, Sumiya, author.

Contributor:

Wang, Lifeng

Zhang, Geng

Conference Name:

International Mobility Conference (2012-01-08 : New Delhi, India)

Language:

English

Physical Description:

1 online resource

Place of Publication:

Pune, MH The Automotive Research Association of India 2012

Summary:

This paper describes the development results of S tolerantPt-Pd-based Diesel Oxidation Catalyst (DOC) which can be appliedfor passive DOC application, targeting Euro 4 and India BS4emission standards with a view of the fact that in India the sulfurcontent is different in the 13 main cities compared to rest of thecountry.In order to develop a cost-effective DOC to meet Euro 4 andIndia BS4 legislation, Pt-Pd-based DOC was studied.Firstly, the effect of Pd used together with Pt in catalyticoxidation performance was studied. DOCs having different Pt to Pdratios were evaluated in the engine exhaust. The results revealedthat CO (Carbon Monoxides) and HC (Hydrocarbons) oxidation activityover Pt-Pd DOC were significantly improved as compared to Pt-onlyDOCs. It was also revealed that there is an optimum Pt to Pd ratioto give the best light-off performance under conditions tested.Advantage of Pd use with Pt was also confirmed in terms of thermalstability. The Pt-Pd DOC was able to suppress more of PGM (PlatinumGroup Metals) crystallite size growth as compared with Pt-only DOCat higher temperature aging. However, higher Pd ratio in DOC withconventional washcoat technology resulted in more rapiddeactivation in CO and HC oxidation activity than a Pt-only DOC, ina steady state activity test conducted in the presence of SO₂.To improve S tolerance over Pt-Pd DOC, effect of washcoattechnology was studied considering thermal stability and SO₂adsorption/desorption properties. In laboratory TPD (TemperatureProgrammed Desorption) testing, it was found that one of the newlydeveloped washcoat technologies significantly improved SO₂desorption property. On this new technology, adsorbed SO₂ wasdesorbed at lower temperature than commercially availableconventional washcoat technology. Residual SO₂ in catalyst bricksafter S poisoning test was carried out with XRF (X-ray FluorescenceAnalysis) analysis to confirm residual S in the catalyst aftersulfation. The result revealed that S content in newly developedwashcoat technology was the lowest among the washcoats tested.These results indicated that newly developed washcoat technologyhas significantly different SO₂ adsorption and desorptionproperties. It suppresses SO₂ adsorption and enhances desorption ofSO₂ adsorbed.Catalytic activity of new Pt-Pd DOC was evaluated and it wasconfirmed that the new DOC significantly improved S tolerancebecause it maintained stable CO and HC oxidation activity in asteady state test conducted in the presence of SO₂. In addition, itwas demonstrated that its catalytic activity can be recovered fromsulfur poisoning when it was exposed to high temperature conditionin the engine exhaust

Notes:

Vendor supplied data

Publisher Number:

2012-28-0009

Access Restriction:

Restricted for use by site license