Experimental and Modeling Study on the Thermal Aging Impact on the Performance of the Natural Gas Three-Way Catalyst



WCX SAE World Congress Experience
Authors Abstract
The prediction accuracy of a three-way catalyst (TWC) model is highly associated with the ability of the model to incorporate the reaction kinetics of the emission process as a lambda function. In this study, we investigated the O2 and H2 concentration profiles of TWC reactions and used them as critical inputs for the development of a global TWC model. We presented the experimental data and global kinetic model showing the impact of thermal degradation on the performance of the TWC. The performance metrics investigated in this study included CH4, NOx, and CO conversions under lean, rich, and dithering light-off conditions to determine the kinetics of oxidation reactions and reduction/reforming/water-gas shift reactions as a function of thermal aging. The O2 and H2 concentrations were measured using mass spectrometry to track the change in the oxidation state of the catalyst and to determine the mechanism of the reactions under these light-off conditions. The experimental data indicate that the NOx and CH4 conversions were higher under rich lambda conditions, thereby generating more NH3 than that observed under lean lambda conditions. Conversely, the NH3 formation was mitigated under the dithering conditions resulting from the recovery of redox properties. The measured O2 and H2 concentration profiles indicated that the conversion of CH4 was attributed to its reaction with O2 until O2 was fully consumed. Further, it was converted through a reforming reaction that produced H2 when O2 was depleted. Consequently, dithering conditions with a substantial amount of O2 showed a delayed onset of reforming chemistry and NH3 formation than those observed under rich conditions. The global kinetic model was developed based on the O2 and H2 data obtained under lean and rich conditions as inputs. The model predicted the NOx reduction chemistry in the presence of CO and H2, steam reforming, and the total oxidation of methane reasonably well. We also discussed an approach to improve the model predictions for the partial oxidation reaction of methane.
Meta TagsDetails
Kim, M., Dadi, R., Gong, J., and Kamasamudram, K., "Experimental and Modeling Study on the Thermal Aging Impact on the Performance of the Natural Gas Three-Way Catalyst," SAE Technical Paper 2023-01-0375, 2023, https://doi.org/10.4271/2023-01-0375.
Additional Details
Apr 11, 2023
Product Code
Content Type
Technical Paper