Nanoscience and Microsystems ETDs

Publication Date

Spring 1-12-2022

Abstract

Pt-based catalysts are used for the treatment of emissions from vehicles, particularly in Diesel oxidation catalysts (DOCs). Three-way catalysts are treated at temperatures ranging from 950℃-1050℃ while DOCs are aged at 800℃ for 50 hrs. At 800°C, Pt reacts with O2 to form PtO2 which has a high vapor pressure and can be transported through the vapor phase. These accelerated aging conditions lead to the formation of large Pt particles causing a loss of catalytic activity. In this thesis, we used model thin-film catalysts that made it possible to quantify the emission of Pt to the vapor phase during accelerated aging. I showed that confining the Pt in nano-porous structures will slow the rate of particle growth leading to improved catalytic activity.

The next phase of this project focused on developing ways that could help with the sintering and emission problem which included coating mesoporous structures with silica as well as exploring other novel pore structures that could be beneficial towards the improved reactivity of the catalysts.

The final part of this thesis explored the role of Pd in suppressing the rate of Pt emission in powder catalysts and understanding the mechanism of the transport of mobile species. The work provides insights into the role of Pt-Pd bimetallic in slowing the sintering of Pt by Pd through the formation of Janus particles which lower the chemical potential of metallic Pt. This research will have significant benefits in cleaning up the pollutants emitted from automobiles hence leading to improved health.

Keywords

Diesel Oxidation Catalyst, Emission Control, Janus Particles, Pore Confinement, Microstructure, Coating

Document Type

Dissertation

Language

English

Degree Name

Nanoscience and Microsystems

Level of Degree

Doctoral

Department Name

Nanoscience and Microsystems

First Committee Member (Chair)

Abhaya K. Datye

Second Committee Member

Adrian Brearley

Third Committee Member

Fernando Garzon

Fourth Committee Member

Gongshin Qi

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