[CCoE Notice] PhD Defense: Optimization strategies and numerical modeling of multi-functional automotive catalysts

[Knudsen, Rachel W]

NAME: Sotirios (Sam) Malamis

DATE: Thursday, October 31, 2019

TIME: 4:00 P.M.

PLACE: Chemical Engineering Conference Room

CHAIR/ADVISOR: Dr. Michael P. Harold
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TITLE:
Optimization strategies and numerical modeling of multi-functional automotive catalysts

Multifunctional automotive catalysts provide new opportunities for gasoline and diesel engines to meet the strict emissions and fuel economy standards from various regulatory agencies. Meeting these demands is important not only for securing industrial compliance  but also for improving human health and air quality. Combining multiple functions into a single catalyst saves design space and reduces material cost. Here we conduct steady state and transient experiments on multi-functional catalysts that span the operational range of gasoline and diesel engines including cold start and high-temperature steady operations to reduce NOx­ and hydrocarbon (HC) emissions. We investigate first the Three-Way NOx Storage Catalyst (TWNSC), a concept that combines three-way and NOx storage functionalities for optimal performance during high-temperature vehicle operation. A series of experiments shows the existence of optimal parameters that maximize conversion and performance for application with a downstream selective catalytic reduction (SCR) catalyst. Second, we characterize new catalysts that address the cold start issue of modern engines, namely the Lean Hydrocarbon NOx Trap (LHCNT) concept. The LHCNT is a precious group metal (PGM)-Zeolite material that combines low temperature NOx and hydrocarbon storage and catalytic conversion of these species into a single unit. By conducting transient uptake and release experiments we obtain useful insight about competitive adsorption, release temperature, conversion activity, and water impact. We find that hydrocarbon concentration and identity, as well as PGM content and zeolite geometry can affect NOx/HC uptake and release performance. We then use results from single component experiments to conduct a configurational study that uses sequential or dual-layered systems to improve the overall LHCNT performance. These results provide guidance for improving catalytic systems in the automotive catalysis industry in order to keep up with emission standards.
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