Lean de-NOx Catalysts
The gasoline direct injection (GDI) engine operating in stratified charge mode is a a lean-burn spark-ignited engine that gives 20 – 30% higher fuel efficiency compared to the conventional stoichiometric engine The diesel engines also operate with 40% or more excess air. The 3-way catalytic converter cannot provide NOx reduction in the lean burn SI and the diesel engines. Lean de-NOx catalyst technology has been developed to meet the needs of these engines. Two main types of lean de-NOx catalyst technology are;
- NOx storage-reduction (NSR) catalyst or NOx trap
- Selective catalytic reduction (SCR)
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