Closed loop controlled three way catalyst

It is not easy to correlate the results obtained in each of the different cycles, because the technology mounted on a vehicle to achieve given emission targets might differ from country to country. Keeping this in mind, Fig. 9 shows the correlation between the emissions obtained in the US-FTP 75 cycle and in the European cycle, for some selected gasoline passenger cars equipped with closed-loop-controlled three-way catalysts [4],... 

The first concept is the closed-loop-controlled three-way catalyst. In this, one type of catalyst, which is placed in the exhaust gas stream, is able to promote all the main reactions that lead to the simultaneous removal of carbon monoxide, hydrocarbons and nitrogen oxides. To balance the extent of the oxidation and the reduction reactions, the composition of the engine-out exhaust gas is maintained at or around stoichiometry. This is achieved by a closed-loop engine operation control, in which the oxygen content of the engine-out exhaust gas is measured up-stream of the catalyst with an electrochemical oxygen sensor, also called lambda sensor. 

Because of its performance in promoting the main reactions to reach completion and at the same time minimizing the extent of the secondary reactions, the closed-loop-controlled three-way catalyst has become the most widely applied technique for catalytic emission control. 

The oxygen storage ability widens the range of exhaust gas compositions at transient operation under which the closed-loop-controlled three-way catalyst has opti-... 

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See also in sourсe #XX -- [ ]

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