Dynamic structure of platinum particles optimizes exhaust gas aftertreatment, German-French cooperation, publication in the journal 'Angewandte Chemie'
Reducing pollutant emission of vehicles and meeting stricter exhaust gas standards are major challenges when developing catalytic converters. A new concept might help to efficiently treat exhaust gases after the cold start of engines and in urban traffic and to reduce the consumption of expensive noble metal.
It is based on the interaction between platinum and the cerium oxide carrier to control catalytic activity by short-term changes of the engine's operation mode, researchers report in the journal Angewandte Chemie (Applied Chemistry).
Thanks to its good catalytic properties, platinum is often applied in catalytic converters of vehicles. Presently, about 60% of European platinum trade are used for this purpose. Using a diesel oxidation catalytic converter (DOC), in which afterburning of hydrocarbons and carbon monoxide takes place, the scientists of Karlsruhe Institute of Technology (KIT) and their partners found that the particle size and oxidation state of the platinum component during operation can be modified specifically.
Interactions between the carrier material and the applied noble metal play an important role. The results reflect a highly dynamic catalytic converter surface that reacts extremely sensitively to external impacts, such as exhaust gas composition. The researchers present ways of using this dynamics to improve catalytic converters.
"The special thing is that we can adjust the size and state of the noble metal nanoparticles on the surface of the catalytic converter. The methods enable us to do this under relevant and even real operation conditions and, hence, to directly adjust the catalytic activity of materials," says Andreas Gänzler, scientist of KIT's Institute for Chemical Technology and Polymer Chemistry (ITCP) and main author of the study "Tuning the Structure of Platinum Particles on Ceria In Situ for Enhancing the Catalytic Performance of Exhaust Gas Catalysts" published in the latest issue of the journal Angewandte Chemie (Applied Chemistry).
In their study, the researchers demonstrated how sensitively the state of platinum reacts to the composition, i.e. the ratio of carbon monoxide and oxygen, and the temperature of the exhaust gas. Engine operation already is modified specifically in exhaust gas aftertreatment systems used today. In this way, exhaust gas composition is adjusted for the regeneration of particulate filters or NOx storage catalytic converters. The study reveals that it is also possible to optimally set the active platinum component in order to enhance activity of the catalytic converter and reduce the consumption of noble metal.
In the course of the German-French cooperation project, complex methods were used to observe the materials under operation conditions. By means of environmental transmission electron microscopy (ETEM), structural modifications on the atomic level of the material were visualized. X-ray absorption spectroscopy at the SOLEIL synchrotron in the French St. Aubin and at the KARA Karlsruhe Research Accelerator of KIT was applied to study the processes under realistic exhaust gas conditions. "Based on these observations of catalytic converter materials under real conditions, findings can be transferred much more quickly to application," Gänzler points out.
With the help of the findings obtained, catalytic activity of diesel oxidation catalytic converters can be enhanced at low temperature. From their observations, the scientists derived a promising basic concept to specifically adjust the size and structure of platinum particles as a function of the catalytic activity required during operation. The concept can be used among others to significantly improve catalytic performance after the cold start of combustion engines and when driving in urban traffic. "The structure of the noble metal nanoparticles can be influenced by short-term modifications of the engine operation mode, for instance," Gänzler says.
Based on the findings, current and future new types of catalytic converters can be improved and their economic efficiency can be increased, as the noble metal concentration can be reduced by up to 50%. The study that is considered "one of the big highlights in catalytic converter research" by Professor Jan-Dierk Grunwaldt of ITCP meets with big interest of experts. It was carried out in the course of the project "ORCA - Oxidation/Reduction Catalytic Converter for Diesel Vehicles of the Next Generation" that is part of the Deufrako German-French research collaboration. The project is funded with EUR 960,000 by the Federal Ministry for Economic Affairs and Energy. Apart from KIT, the Institut de Recherches sur la Catalyse et l'Environnement de Lyon (IRCELYON), TU Darmstadt, the Solvay company, and Umicore AG & Co. KG, a materials technology and recycling company in Hanau, take part in the collaboration project.
Andreas M. Gänzler, Maria Casapu, Philippe Vernoux, Stéphane Loridant, Francisco J. Cadete Santos Aires, Thierry Epicier, Benjamin Betz, Rüdiger Hoyer, and Jan-Dierk Grunwaldt: Tuning the Structure of Platinum Particles on Ceria In Situ for Enhancing the Catalytic Performance of Exhaust Gas Catalysts. DOI: 10.1002/anie.201707842
More about the KIT Mobility Systems Center http://www.
For further information, please contact:
Kosta Schinarakis, Science Scout, Phone: 49-721-608-41956, Fax: 49-721-608-43658, Email: firstname.lastname@example.org
Being "The Research University in the Helmholtz Association," KIT creates and imparts knowledge for the society and the environment. It is the objective to make significant contributions to the global challenges in the fields of energy, mobility and information. For this, about 9,300 employees cooperate in a broad range of disciplines in natural sciences, engineering sciences, economics, and the humanities and social sciences. KIT prepares its 26,000 students for responsible tasks in society, industry, and science by offering research-based study programs. Innovation efforts at KIT build a bridge between important scientific findings and their application for the benefit of society, economic prosperity, and the preservation of our natural basis of life.
Since 2010, the KIT has been certified as a family-friendly university.
This press release is available on the internet at http://www.
Monika Landgraf | EurekAlert!
Climate Impact Research in Hannover: Small Plants against Large Waves
17.08.2018 | Leibniz Universität Hannover
First transcription atlas of all wheat genes expands prospects for research and cultivation
17.08.2018 | Leibniz-Institut für Pflanzengenetik und Kulturpflanzenforschung
New design tool automatically creates nanostructure 3D-print templates for user-given colors
Scientists present work at prestigious SIGGRAPH conference
Most of the objects we see are colored by pigments, but using pigments has disadvantages: such colors can fade, industrial pigments are often toxic, and...
Scientists at the University of California, Los Angeles present new research on a curious cosmic phenomenon known as "whistlers" -- very low frequency packets...
Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.
When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...
Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.
Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....
Proteins must be folded correctly to fulfill their molecular functions in cells. Molecular assistants called chaperones help proteins exploit their inbuilt folding potential and reach the correct three-dimensional structure. Researchers at the Max Planck Institute of Biochemistry (MPIB) have demonstrated that actin, the most abundant protein in higher developed cells, does not have the inbuilt potential to fold and instead requires special assistance to fold into its active state. The chaperone TRiC uses a previously undescribed mechanism to perform actin folding. The study was recently published in the journal Cell.
Actin is the most abundant protein in highly developed cells and has diverse functions in processes like cell stabilization, cell division and muscle...
17.08.2018 | Event News
08.08.2018 | Event News
27.07.2018 | Event News
17.08.2018 | Physics and Astronomy
17.08.2018 | Information Technology
17.08.2018 | Life Sciences