Spatio-Temporal Phenomena During Adsorption and Reaction in Hydrocarbon Traps

University Of Houston, Houston TX

Investigators

Abstract

PI: Harold, Michael Institution: University of Houston Proposal Number: 1067709 Title: Spatio-Temporal Phenomena During Adsorption and Reaction in Hydrocarbon Traps The PIs plan to conduct in situ experimental measurements and modeling of simultaneous trapping and oxidation of hydrocarbon mixtures on precious metal based zeolite catalysts during transient warmup and low temperature operation. The information will be used for the design of a diesel oxidation catalyst (DOC) reactor configuration that satisfies new stringent emission limits. The central activity will be to study the effects of the geometric and compositional properties of the bi-functional trapping catalyst on the transient oxidation of model exhaust components. The research will determine the relative performance of several different catalyst architectures spanning sequential, segmented, and dual layer designs. Using a set of in situ experimental techniques the PIs will follow the spatio-temporal features of this class of fast, exothermic, transient catalytic oxidations. These will collectively provide detailed information about coupled concentration and temperature fronts during low temperature hydrocarbon trapping and oxidation. The distributed temperature scanning measurements in a chemical reactor will provide data that could not be previously obtained. The work to be done includes: 1. Carry out intrinsic kinetics studies of hydrocarbon trapping and oxidation in a bench-flow reactor and temporal analysis of products (TAP) reactor on Pt/Pd/zeolite-Beta /ã-Al2O3 catalysts. 2. Use spatially-resolved mass spectrometry to measure the temporal concentration profiles of reacting species during hydrocarbon trapping and oxidation on the model catalysts. 3. Use distributed temperature sensing with swept-wavelength interferometry (DTS-SWI) to measure the spatio-temporal temperature profile inside several channels of a washcoated monolith during hydrocarbon trapping and oxidation. 4.Conduct comprehensive experiments utilizing spatially-resolved mass spectrometry, swept-wavelength interferometry, and integral diffuse-reflectance IR spectroscopy to map spatial and temporal behavior of model hydrocarbon trapping and oxidation reaction system. 5. Develop a spatio-temporal model to simulate hydrocarbon trapping and oxidation that captures the main trends observed in the model reaction system. 6.Synthesize mixed-layer and dual-layer washcoated catalysts containing the precious metal (Pt, Pd) and hydrocarbon adsorbent (zeolite-Beta) on an alumina support. 7. Carry out validation experiments using actual diesel vehicle exhaust. The intellectual merit of this project is to advance knowledge and understanding of reliability issues and optimal operation of a time-varying catalytic process of practical significance, the diesel oxidation catalyst (DOC). That knowledge will be applicable to transient operation of other catalytic reactors such as packed beds. The research will enable development of predictive adsorptive reactor models of the hydrocarbon trap, design of critical experiments, and identification of optimal performance of various reactor configurations under transient operation. Enabling the oxidation of the exhaust components during the cold start and low temperature operation is a demanding technological challenge. The PIs expect that the understanding and insight generated by the study will lead to a novel catalyst designs and operation and control strategies approach that minimize the breakthrough of pollutants from the DOC. The broader impact is the development of novel experimental methodologies to determine spatio-temporal features of transient catalytic reactors. The research will introduce to the reaction engineering community the application of new experimental methods, including spatially resolved mass spectrometry, distributed temperature sensing, and isotopic temporal analysis of products. Research findings will be disseminated in archived journals utilized by practitioners in the petrochemical and environmental industries. The PIs will also provide reactor codes to the scientific community and will incorporate findings from the research into graduate level courses at UH. The project will be used as a technology platform to attract interest in engineering science among high school students and graduate research among undergraduate students. This will be accomplished through the involvement of undergraduate students in the project, and a summer internship offered to high school science teachers.