Diesel innovation and leadership in core technological and scientific competencies are the key drivers for European competitiveness. In this context, diesel engine improvements towards more efficient and less polluting vehicles play a critical role in the competitiveness of the European car industry and in the long-term sustainable growth and job preservation in Europe, along with the necessary improvement of air quality and reduction of health effects. In the next ten years, it is anticipated that a smooth transition from conventional engines to new diesel technologies will happen (from conventional to partially homogeneous and then to finally homogeneous over a wide range of operating points). Diesel Homogeneous Charge Compression Ignition (HCCI) combustion processes are seen as a promising way to meet the future environmental challenges, which will have to achieve both significantly lower pollutant emissions and fuel consumption.
With these concepts, NOx and PM emissions are simultaneously drastically reduced avoiding the installation of a complex and costly NOx specific after treatment. The main drawback of this concept is that the level of low-temperature related emissions, i.e. CO and HC, can increase by several orders of magnitude. This implies that conventional oxidation catalysts' technologies, currently used on Euro IV compliant vehicles, are no more able to convert these harmful emissions because of the saturation of the active catalytic sites.
As a result, such increased CO and HC emissions have to be reduced to safe levels using innovative catalysts or emergent technologies, which have to be characterised by a different reaction kinetic, so are less dependant on the pollutants' concentration. It is also admitted that such innovative combustion processes will merge with an increasingly wider diffusion of new fuel properties and renewable formulations, so that will be helpful to enlarge the engine running range (EUCAR RENEW project). The impact of these new fuel formulations on next-generation after treatment processes will also have to be investigated.
The aim of the project was to provide a comprehensive, system-oriented view on potentially new after-treatment processes that will be required for the next HCCI combustion systems taking into account the next fuel generation.
The scientific objectives of this project were:
- to understand the complex kinetic mechanisms and chemical principles of CO/HC low temperature oxidation for the next generation diesel engines exhaust environment;
- to develop a robust, efficient, and accurate computational models to analyse, simulate and improve the performance of next generation catalytic converters (a transient one-dimensional model and a single spatial dimension will be developed as a first step, and then 2D and 3D calculations will be investigated and integrated).
The technological objectives were:
- to formulate, develop, test and optimise advanced new catalyst formulation for CO/HC low temperature oxidation;
- to design, develop and test emerging flexible low temperature oxidation technologies based on plasma concepts;
- to perform a powertrain system synthesis and evaluate, for the next generation powertrains, the requirements and boundary conditions needed to implement the advanced after treatment processes in diesel engines.
The project worked through four main identified and focused directions:
- low temperature oxidation of CO and HC: fuel effect and oxidation mechanism in advanced homogeneous combustion processes;
- advanced new catalyst formulations for high CO, HC concentration and low temperature oxidation;
- emerging flexible low temperature oxidation technologies;
- system synthesis for next powertrain generation.
WP 1: Low temperature oxidation of CO and HC: fuel effect and oxidation mechanisms in advanced homogenous combustion processes.
The transverse work package WP1 was dedicated to the scientific and research activities on low temperature oxidation of high levels of CO and HC emissions, as created by HCCI-like combustion modes. This item was divided into data collection, complementary emissions measurements and modelling parts. From data collection and complementary emissions measurements part, the main objective was to get reliable data on CO and HC emissions and exhaust temperatures for the further system definition and to supply boundary conditions for the simulations tools. The modelling aim was then the development of innovative tools for the design and the improvement of exhaust lines using the developed advanced catalytic devices.
WP 2: Advanced new catalyst formulations for high CO, HC concentration and low temperature oxidation.
During WP2, fundamental investigation of advanced catalyst formulation for low temperature oxidation of high level of CO and HC was performed by Chalmers University in collaboration with CRF and JM. The work carried out between the three partners allowed us to determine the best catalyst components and preparation route to use for improved catalytic activities in respect to HCCI conditions. Newly developed technologies were benchmarked against the Johnson Matthey reference catalyst, current commercially available technology. Scale up studies of the new formulation (JM) and synthetic gas bench measurements (JM and CRF) were carried out to ensure that the newly developed catalyst has the same properties as the catalyst powder developed previously by Chalmers University. Progresses in terms of catalyst performance, conversion efficiency, low light-off temperature, poisoning effects, durability and precious content metal were monitored and reported during the project.
It was shown during this project that catalyst performance can be significantly improved with the new developed formulation. Testing of the advanced DOC formulation show that increasing CO concentration will increase performances due to positive order kinetics of CO regarding platinum supported on ceria. Low temperature oxidation was improved while minimising in the same time the cost of the DOC introducing larger amount of palladium in the catalyst formulation. Substituting platinum with palladium in DOCs results in precious metal cost saving and will improve thermal stability and
The results of PAGODE will help automobile industry to develop affordable innovative technical solutions dedicated to the future diesel engine. PAGODE is the place where complementary skills are joining their efforts to answer technological challenges on the after treatment of the next generation of diesel engine.