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Gasoline Cold Start Concept (gCSC™) Technology for Low Temperature Emission Control
Abstract:
Stricter emission standards in the near future require not only a high conversion efficiency of the toxic air pollutants but also a substantial reduction of the greenhouse gases from automotive exhaust. Advanced engines with improved fuel efficiency can reduce the greenhouse gas emissions; their exhaust temperature is, however, also low. This consequently poses significant challenges to the emission control system demanding the catalysts to function at low temperatures both during the cold start period and under the normal engine operation conditions. In this paper, we will introduce a gasoline Cold Start Concept (gCSC™) technology developed for advanced stoichiometric-burn gasoline engines to meet future stringent emission regulations.
To improve the low temperature performance of three-way catalysts, a novel Al2O3/CeO2/ZrO2 mixed oxide was developed. Compared to conventional CeO2/ZrO2 mixed oxides with similar compositions, the new material exhibits higher oxygen storage capacity especially at low temperatures and is more thermally durable. The improved thermal stability of the new material further stabilizes and improves the PGM dispersion on the support. As a result, low temperature TWCs based on the new material exhibit a reduced light-off temperature. The improvement becomes obvious when the catalysts are tested on a vehicle with low exhaust temperatures.
For cold start HC emission control, HC storage components were further improved to increase the HC trapping capacity and HC release temperature. An emission control system combining the improved low temperature TWC and the enhanced HC trapping components demonstrates a noticeable reduction in the tailpipe emissions.