A design strategy applied to sulfur resistant lean NOx̳ automotive catalysts

Catalyst poisoning due to sulfur compounds derived from fuel sulfur presents a major challenge, intractable thus far, to development of many advanced technologies for automotive catalysts such as the lean NOx, trap. Under lean conditions, sulfur will be oxidized to S0₃ and then form sulfate on the trap. The sulfate on the trap is thermodynamically very stable and, thus, difficult to purge. The NOx trap will then be deactivated over time. Our objective has been to build up a framework for the design of selective, sulfur resistant, oxidation automotive catalysts, which are active for the oxidation of NO to NO₂ but relatively inactive for the oxidation of SO₂ to S0₃. It is well known that the catalytic properties of alloys are often superior to those of pure metals, because of either the electronic effect or the ensemble effect or both. The ensemble effect is due to a change in distribution and availability of surface reaction sites, while the electronic effect is due to a change in electronic structure, leading to a change in rate constants of elementary steps. However, a very large number of possible compositions of alloys exist for any particular application.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Chemical Engineering.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2005

Author dc:creator

• Tang, Hairong

Advisor dc:contributor.advisor

• Bernhardt L. Trout.

• Chemical Engineering.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/33717

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/33717