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Title: Evaluation of Diesel Oxidation Catalyst with Ultra-Low Nitrogen Dioxide Emissions
Authors: Loai Mohamed Ibrahim Ben Naji 
Supervisor: Dr. Osama Mohamed Ibrahim
Keywords: Diesel Oxidation : Nitrogen
Issue Date: 2018
Publisher:  Kuwait university - college of graduate studies
Abstract: The aim of this study is to evaluate the performance of a newly developed Diesel Oxidation Catalyst (DOC) that is designed to selectively oxidize carbon monoxide (CO) and hydrocarbons (HC) into carbon dioxide (CO2) and water (H2O) and reduce nitrogen dioxide (NO2) into nitric oxide (NO). This newly developed catalyst, which is referred to hereinafter as an ultra-low-NO2 DOC, is based on palladium and tungsten (Pd-W) and supported by a nano-washcoat that consists of aluminum and yttrium oxides (Al2O3-Y2O3). The ultra-low-NO2 DOC is intended to be integrated with an Active Diesel Particulate Filter (ADPF) as a complete emissions control system that reduces CO, HC, NO2, and Particulate Matter (PM). The study has two specific objectives: (1) to quantify gaseous diesel emissions reduction by the newly developed catalyst; and (2) to investigate the formation of aluminum oxide (Al2O3) on the surface of sintered FeCrAlly fibers by thermal oxidation. The emissions measurements were performed by the Emission Research and Measurement Division of Environment Canada and by Intertek Automotive Research in Texas, USA. The diesel emissions results showed the importance of balancing the oxidation and reduction catalyst to obtain a high level of CO and HC oxidation while maintaining a high level of NO2 reduction. In the absent of the oxidation catalyst, as expected, there was an increase in CO emissions and no significant reduction in HC emissions. Nitrogen oxides (NOx) emissions, however, were reduced by about 8%, and NO2 emissions were eliminated completely, by 100%. The emissions results of the catalyzed ADPF, on the other hand, show that the catalyst selectively oxidizes CO and HC into CO2 and H2O, and reduce NO2 into NO, resulting in over 54% reduction in CO emissions, 84% in HC, and 100% reduction in NO2 emissions. No significant reduction in NOx was observed. Coated and uncoated sintered-metal-fibers were analyzed to evaluate the distribution of the Al2O3-Y2O3 nano-washcoat and Pd-W catalysts using the Energy Dispersive Spectroscopy (EDS). The analysis helped to identify and quantify the distribution of the nano-particles and the catalysts on the fiber surface. The results of the analysis show that the nano-washcoat was not distributed evenly on the surface of the metal fibers. The results also revealed the need to optimize the distribution of the Al2O3-Y2O3 nano-particles on individual metal fibers to obtain a uniform coating with nano-structures that maximize the surface area to improve the performance of the catalyst. The results of the thermal oxidation have displayed the different morphology of Al2O3 layers formed on the surface of the FeCrAlly fibers. In this study, 6 samples of sintered FeCrAlly fibers were considered. These samples were heat treated at single and multi-stage temperatures from 700oC to 1000oC. The results show that as the temperature increases the aluminum diffusion on fiber surface also increases, resulting in more aluminum and less iron on the surface.
Appears in Programs:0630 Mechanical Engineering

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