Browse Publications Technical Papers 2019-26-0133

Optimization of Performance of Oxygen Storage Component (OSC) for NO Reduction in Three Way Catalysts to Achieve BS VI Emission Norms 2019-26-0133

Three way catalysts used in Gasoline / CNG operated vehicles contains oxygen storage component (OSC) as a key component and source for supplying oxygen in rich mode of operation and the oxygen concentration release rate is function of gas concentration and air to fuel ratio (A/F) or lambda (λ). Conventionally, the vehicles (two wheelers) operated using mechanical method such as carburettor, having lambda range is of wider window (0.95 ~ 1.06) and to cover this window, catalyst usually requires a large amount of OSC resulting in to a significant drop in NO conversion as a function of temperature, reductant concentration while switching from rich to lean to regenerate CeO2 sites. Moving from BS IV to BS VI, the NOx conversion requirement is over 90% including deterioration factor limit and thus requires a tight control in terms of lambda as well as OSC optimization. The need for OSC optimization is attributed to controlled amount of oxygen release during rich period of operation leading to lower down exotherms, maximization of NO reduction using CO as reductant & minimizing CO consumption for CeO2 regeneration keeping other reaction parameters constant. In present study, OSC effects were being extensively studied by using various formulations comprising of different OSC levels as a function of temperature and reductants concentration. The OSC's were selected & evaluated on the basis of various properties such as surface area, crystal size and amount of oxygen stored. The washcoat derived from above combinations were coated on ceramic honeycomb. The catalysts were evaluated for physical properties such as surface area, pore diameter, pore size distribution etc. as well as NO reduction activities as ' Fresh' and 'Aged' on synthetic gas test bench. The drop in NO reduction was found to be lowered compared to conventional catalyst when aged at 1100℃ for 5 hrs.


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