[CCoE Notice] Cullen College Dissertation Defense Announcement - Abhay Gupta

[Knudsen, Rachel W]

[Dissertation Defense Announcement at the Cullen College of Engineering]
Analysis and Design of Structured Multi-Functional Trapping Catalysts for Conversion of Hydrocarbons and NOx from        Diesel and Advanced Combustion Engines


Abhay Gupta
July 15, 2022;  10:00 AM – 12:00 PM (CST)

Room: Chemical Engineering Conference Room

Zoom link: https://urldefense.com/v3/__https://uh-edu-cougarnet.zoom.us/j/97606567523?pwd=aXh0N1ZGNURmSmRudnJKQS9WaW1sUT09__;!!LkSTlj0I!DvGE01-obE5YNsal67UfuAgN_LuPHJt1Xz0Yyq4tCZhX-YFXQQKC4nO6CEcpSO0n_ek_TaX369UsI6QugQYG02HL$ 
    Meeting ID: 976 0656 7523
     Passcode: 343599


Committee Chair:
Michael P Harold, Ph.D.
Committee Members:
Lars C Grabow, Ph.D. | Jeffrey D. Rimer, Ph.D. | Stanko R. Brankovic, Ph.D. | Stacey M Louis, PhD.
Abstract
Multifunctional automotive catalysts can help abate harmful emissions, such as NOx (x=1, 2), CO and hydrocarbons (HCs) and provide a potential solution to meet the need of increasingly stringent vehicle fuel economy standards and emissions regulations. The proposed LHCNT (lean hydrocarbon NOx trap) concept involves the combination of NOx trapping with HC trapping and oxidation for conversion of NOx, HC, and CO during sustained, low temperature exhaust drive cycles and engine cold-start. In first part of the work we focus on NOx uptake and release features on Pd-exchanged SSZ-13 (PNA- Passive NOx Adsorber) catalyst to trap NOx in the absence and presence of several diesel exhaust components (CO, C2H­4, H2, C7H8, and C12H26). We identified two prospective mechanistic schemes which are consistent with the uptake/release and DRIFTS (diffuse reflectance infrared Fourier transform spectroscopy) data. Second we focused on DOC (Diesel Oxidation Catalyst) which is an essential component of modern vehicle emissions control systems. A new Pd-Cu alloy catalyst ((Pd+Cu/SiO2-Al2O3), prepared in-house, exhibited higher resilience to increased light-off temperature, resultant of mutual inhibition between the various pollutants, in comparison with the commercial DOC (Pt+Pd/Al2O3-CeO2). The benefit of eliminating the inhibition effect of NO on CO oxidation is clearly demonstrated in the juxtaposition of the two catalyst and reactor configurations using a CO and NO containing feed. Next we investigate the spatiotemporal features of a multifunctional monolith lean hydrocarbon NOx trap (LHCNT) for eliminating NOx and C2H4 in simulated diesel exhaust. Spatially-resolved mass spectrometry (SpaciMS) is used to measure the temporal species concentration profiles spanning the sequentially-positioned PNA (Pd/SSZ-13), HCT (Hydrocarbon Trap; Pd/BEA) and DOC (Pt/Al2O3-CeO2) zones. The working concept of the LHCNT is demonstrated through measured integral trapping efficiency profiles, which show NO and C2H4 trapping followed by delayed NO release along with NO and ethylene oxidation during the simulated warmup. Finally, we utilized the same sequential configuration system to identify impact of CO on NO trapping. Conditions are identified which lead to CO induced deactivation. We conclude our study with the scope of the future work based on our results and observations.
[Engineered For What's Next]

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