[CCoE Notice] Cullen College Dissertation Defense Announcement - Pak Wing Chen

[Hutchinson, Inez A]

[Dissertation Defense Announcement at the Cullen College of Engineering]
ENHANCED METHANE CONVERSION OVER FOUR-WAY CATALYST FOR STOICHIOMETRIC NATURAL GAS VEHICLES EMISSION CONTROL

Pak Wing Chen
June 26, 2023;   3:00 PM

Room: Chemical Engineering Conference Room- S234
                              Teams: Meeting ID: 281 567 354 398  Passcode: BbJ4fx

Committee Chairs:
Michael P. Harold, PhD and Lars Grabow, PhD
Committee Members:
Jeffrey Rimer, Ph.D. | Stanko Brankovic, Ph.D. | Ru-Fen Liu, Ph.D.
Abstract
          Effective emission control technology is needed for purification of the exhaust gas from stoichiometric natural gas vehicles (NGVs), to meet the increasingly stringent tailpipe emissions regulations on vehicles powered by internal combustion engines. This requires the development of a four-way catalyst (FWC) that can convert methane, non-methane hydrocarbons, CO and NOx simultaneously. The current project focuses on methane conversion over the platinum group metal (PGM) based catalyst with spinel oxide as oxygen storage material (OSM). The added catalyst functionality from the OSM component requires detailed investigations of the catalyst performance.
          The catalyst performances are evaluated from both experimental and modeling perspectives. In the experimental parts of the work, the catalysts were tested using lab scale flow experiments under conditions close to the exhaust gas of stoichiometric NGVs. The combination of lean/rich feed modulation and the addition of spinel allows for enhanced CH4 conversion. Systematic and parametric studies that evaluate the catalyst activity over varying feed operation mode (time-invariant or modulated), feed compositions (air-fuel ratio) and feed temperatures were carried out. The impacts of catalyst formulation and structure on the CH4 conversion performance were also analyzed. The dynamic oxygen storage capacity of spinel was found to play a significant part for the CH4 conversion enhancement under lean/rich feed modulation and the reaction mechanism of the PGM+Spinel catalyst is proposed.
          In the modeling aspects of the work, global kinetic models over PGM were developed for the reactions that have been identified to be the main reactions affecting the CH4conversion and product formations, namely water gas shift (WGS), steam reforming of CH4(SRM), total CH4 oxidation and partial CH4 oxidation. The developed kinetic models over PGM are combined with the previously developed kinetic models of catalytic oxidation and dynamic oxygen storage capacity over spinel, and the integrated kinetic models are incorporated into the monolith reactor model. The model simulation results are validated by the experimental data and the model is applied to further the understanding of the catalyst functionalities and to optimize the catalyst performance and formulations.
[Engineered For What's Next]


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