An important step in the reaction is the adsorption of CO on the surface of the catalyst. A team of scientists from the ESRF and the ETH in Zurich (Switzerland) has managed to see how the electrons in the platinum reorganize as the adsorption is taking place and why catalysts are “poisoned”, i.e. why their activity is reduced. It is the first time that this type of experiment is carried out at the same high temperatures and pressures as in a real car exhaust catalyst.
When the CO or other toxic gases get in contact with the catalyst, a noble metal such as platinum, they oxidize to become less dangerous gases. In this case, CO turns to CO2, which the car expels via the exhaust pipe. However, the efficiency of the catalytic conversion decreases considerably when the catalyst is at low temperature. The scientists from the ESRF and ETH in Zurich determined how the CO poisons the surface of the catalyst. The strong bond between CO and the platinum blocks active sites and makes the metal less susceptible to reaction with oxygen, lowering its reactivity.
Scientists around the world have studied thoroughly the electron structure of adsorbed CO using techniques like vibration and soft X-ray spectroscopy, but few have studied the electrons in the platinum, and it has proven extremely difficult to do it on nanoparticles under ambient pressure. In fact, very few experimental techniques are compatible with the required temperature, gas environment, and the low metal concentration of supported nanoparticles.
The team has developed a technique where they can investigate the platinum electrons that take part in the bond with CO. “We have, for the first time, combined a novel experimental and theoretical approach with an important application in catalysis research. This enables us to look at the adsorption of CO on Pt nanoparticles from a new perspective that was previously not accessible” explains Pieter Glatzel, scientist at the ESRF.
The next step is to look at the changes in catalyst structure under actual catalytic conditions, such as those occurring during the preferential oxidation of CO and the water gas shift reaction. “We are very hopeful of this new technique and are sure that it will enable us to improve our knowledge about catalytic systems and, with it, make them better”, says Jeroen van Bokhoven, scientist at the ETH.
Safeguarding sustainability through forest certification mapping
27.06.2017 | International Institute for Applied Systems Analysis (IIASA)
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26.06.2017 | Albert-Ludwigs-Universität Freiburg im Breisgau
An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.
Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...
Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.
Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...
Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.
As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...
Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.
With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...
Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine
Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...
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