Characterization of a New Advanced Diesel Oxidation Catalyst with Low Temperature NO x Storage Capability for LD Diesel

摘要: Currently, two consolidated aftertreatment technologies are available for the reduction of NOx emissions from diesel engines: Urea SCR (Selective Catalytic Reduction) systems and LNT (Lean Trap) systems. technology, which has been widely used many years at stationary sources, is becoming nowadays an attractive alternative also light-duty applications. However, much more effective in efficiency high load operating conditions than light condition, characterized by lower exhaust gas temperatures. One possible solution to improve low temperature behavior, use newly developed Advanced Diesel Oxidation Catalysts (A-DOC) capable store temperatures (typical urban driving conditions) when low, release stored higher (i.e. during extra-urban where urea injected effectively forming ammonia subsequent conversion. Experimental tests were therefore carried out order assess performance A-DOC exposed coming a modern Euro 5, 2.0 L displacement turbocharged Common Rail DI engine typical European passenger car: features DOC DPF close-coupled position, hosted into on purpose designed dismountable canning, thus allowing easy switch between different components. The characterization these newer formulations was performed over NEDC cycles. Moreover, catalyst tested both fresh hydrothermally aged have better understanding relative robustness durability catalyst. storage capability, found be impressively A-DOC, significantly decreased after aging, leading final cumulated figure equals engine-out value A-DOC. Nevertheless, since most occurs EUDC segment, downstream would likely reached appreciable efficiencies, even could provide significant benefits terms reduction. analysis NO/NO2 share DPF, crucial importance temperature, revealed that overall conversion NO negative, while contrary NO2 remarkably high. As result, NO2/NOx ratio inlet SCR) remained whole hindering achievement efficiencies full exploitation synergetic combination with SCR.