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- Type of Document: M.Sc. Thesis
- Language: Farsi
- Document No: 52151 (06)
- University: Sharif University of Technology
- Department: Chemical and Petroleum Engineering
- Advisor(s): Hamzehlouyan, Tayebeh; Khorasheh, Farhad
- Abstract:
- Diesel oxidizing catalysts (DOCs) based on precious metals of Platinum and Palladium are among the most important and most widely used catalysts in the exhaust aftertreatment system of diesel cars. DOCs are used to oxidize CO and hydrocarbons to reduce their emissions to the environment. In spite of the excellent performance of DOCs, sulfur exposure can lead to their deactivation. Sulfur is mainly in the form of SO2 at the combustion chamber exit, which can be further oxidezed to SO3 on the DOC. The deactivation impact of SO2 and SO3 on DOCs are different, with SO3 leadig to higher degrees of deactivation. In this study, a kinetic model for SO2 oxidation on a bimetallic Pt-Pd-based catalyst is developed with the goal of predicting SO3 production on the catalyst and understanding this reaction on different ratios of Pt-Pd. First, two micro kinetic models based on the Langmuir-Hinshelwood mechanism on single-metal Pt/Al2O3 and Pd/Al2O3 catalysts are developed. Then, a kinetic model for this reaction over bimetallic Pt-Pd / Al2O3 catalysts with different ratios of Pt:Pd (i.e. 1:0, 0.85:15, 0.5:0.5, 0.1:0.9, 0:1) is developed. Steady-state conditions and one-dimensional assumption were considered in the model, and a system consisting of algebraic-differential equations was solved at different temperatures to obtain SO2 conversion as a function of temperature. Also, the relative importance of different reaction steps has been investigated at different temperatures to determine the rate determining step of the reaction
- Keywords:
- Platinum-Palladium Alumina (pt-pd/Al2O3) Catalyst ; Sulfur Poisoning ; Disel Oxidation Catalyst (DOC) ; Kinetics Modeling ; Sulfur Dioxide Oxidation Kinetic
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