Oxidation/Reduction CAtalyst for advanced Diesel Vehicles – ORCA

Diesel passenger vehicles represent an attractive long term solution to meet european CO2 emission reduction targets. As they also have to fulfill the stringent European pollutants emissions standards, these vehicles are equipped with complex and expensive aftertreatment systems. Active catalytic elements are Platinum Group Metal (PGM) and Rare Earth metal Oxides (REO), such as doped ceria.
Next generations of Diesel engines will be even more fuel efficient. One of the consequences is the exhaust temperature decrease, obliging the catalytic post-treatment to be much more effective. This activity gain cannot be achieved with higher loadings of PGM and REO as these two families of catalysts are under the 14 critical raw materials with a limited world annual production mainly occurring outside Europe. Therefore, a breakthrough in the formulation of Diesel exhaust aftertreatment catalysts is clearly necessary to achieve higher catalytic activity with lower PGM and REO contents. This issue is crucial for German and French car manufacturers as technology and market leaders in the field of Diesel engines.
The ORCA (Oxidation/Reduction CAtalysts) project will be focus on two functionalities within the Diesel exhaust catalyst system that are responsible for the largest part of PGM and REO usage: the NOx reduction conversion and the low temperature oxidation of carbon monoxide and unburnt hydrocarbons. ORCA aims at developing a new catalyst generation coupling these two functionalities in order to replace both the Diesel Oxidation Catalyst (DOC) and the NOx storage catalyst (NSC), currently used in series. New advanced ORCA catalysts will have to present a higher oxidation capability (below 120°C after aging) than conventional DOC technologies, a better NOx-storage performance (below 200°C) compared to present NSC systems, a sustainable utilization of REO (without any neodymium and a maximum 10wt% of praseodymium oxide), and a reduced PGM amount by about 40% in comparison with state-of-the-art catalysts.
ORCA is based on preliminary results, which show significantly improved low temperature oxidation activity of ceria containing Platinum catalysts after lean/rich conditioning, compared to conventional DOC materials. Since ceria is a NOx adsorber material, this catalyst represents an attractive starting point for a rational optimization of the formulation of ORCA catalysts to achieve the technological objectives.
Two issues will be addressed in parallel by the consortium: the understanding of the PGM/REO interactions and the identification of key functionalities of REO, both in real operating conditions. IRCELYON, KIT and the University of Darmstadt, three leading research laboratories in the field of exhaust gas catalysis, will explore these two issues by implementing advanced operando time-resolved characterizations techniques (X-ray absorption spectroscopy, aberration-corrected environmental transmission electron microscopy,..), deep characterizations of structure-catalytic activity relationships and detailed surface kinetic modeling. RHODIA, a major manufacturer of NOx storage active REO based materials and Umicore, a major producer of PGM for exhaust catalysts, will deliver their expertise in the ORCA catalysts preparation and formulation (textured materials, dopant, PGM impregnation,…), in full size catalyst synthesis and in application testing (latest legislative test cycles and realistic driving).
ORCA is intended to strengthen the technological leadership and competitiveness of RHODIA and Umicore as major players in materials and chemical industry worldwide. It will also create a new platform for scientific exchange and innovation between French and German Universities. The development of ORCA catalysts could reduce the dependence of European industry in PGM and REO supply and promote the development of clean and competitive Diesel passenger vehicles.