Three Way Catalyst

소개글

With increasing interest in global environmental protection, the social demand for cleaner emissions and lower fuel consumption has been growing worldwide. In California, USA, in particular, where emissions must meet the unprecedentedly stringent low emission vehicle(LEV)Ⅱ standard, the industry is required to substantially reduce emissions of hydrocarbons(HC) and nitrogen oxides(NOx). It is therefore necessary to enhance the performance of three-way catalysts. In particular, a high-performance catalyst that can purify exhaust gases even at low temperatures has to be developed.
Conventional measures to cope with the regulations consisted in enhancing the performance of catalysts and improving the engine. Howeber, these approaches are insufficient to meet the recent SULEV and PZEV regulations. Present gasoline engines decrease HC and NOx emissions mainly by using three-way cayalysts. However, 70% of the total HC emission in the driving mode is emitted during the first 100s, suring the "cold start"phase before engine and catalyst are warmed up. It is necessary to be able to adsorb HCs at a temperature below the catalyst`s activation level and then purify them with three-way catalysts as they desorb with increasing temperature.

목차

Background
Definition
Catalytic Converter
Reactions
Kinetics
Heat and Mass Transfer Phenomena
Oxygen Storage Capacity (OSC)
Cold Start and Catalyst Fast Light-off

본문내용

What is TWC?
The catalyst that converts CO and HC to CO2 and H2O, and NOx to N2.
Depending on the chemistry and the physics of the catalyst, and the chemical engineering aspects.
Catalyst must be thermally and mechanically stable.

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