The current strict environmental legislation demands advanced concepts to reduce the emission of harmful gasses by cars. Reducing the emission of nitrous oxides (NOx) emitted by diesel and lean-burn petrol engines is one of the challenges faced. These economical engines produce exhaust fumes that are particularly rich in oxygen and therefore the conventional three-way catalytic converter is not suitable for converting the generated NOx into nitrogen. The current trend is therefore to add specific components such as barium to the catalytic converter to store the NOx formed.
In this new type of NOx Storage Reduction (NSR) catalytic converter the diesel or petrol combustion in the engine takes place alternately over long oxygen-rich and short fuel-rich periods. During a long oxygen-rich period the generated NOx is stored in the barium component. When this component becomes saturated the catalyst is regenerated. This happens during the short fuel-rich period when an oxygen-poor emission gas is produced. The NOx stored is released and subsequently reduced to nitrogen over a precious metal such as platinum. Scholz investigated this NSR mechanism to gain a better understanding of how the storage component functions during the oxygen-rich and fuel-rich periods.
The researcher carried out experiments in a laboratory reactor containing the NSR catalyst. She studied the behaviour of the catalyst in detail, including analysis of the effect of the various forms in which barium occurs in the catalytic converter, the effect of the presence of carbon dioxide and water in the exhaust gas, and the effect of the various reducing agents, such as carbon monoxide, hydrogen, and ethylene on the NOx storage and reduction. The research has yielded important new insights with respect to the function of various components in the catalytic converter. Scholz has also produced a practical mathematical model that describes the various chemical reactions in the catalytic converter.
Knowledge for everyday practice
Using this reaction model, a regulatory system in the car can determine when the maximum NOx capacity of the catalyst has been reached, followed by the length of time extra fuel must be injected to regenerate the catalyst. The research was carried out in cooperation with the car manufacturers PSA Peugeot Citroen, Toyota and Ford, the car development company PD&E Automotive Solutions, catalytic converter manufacturer Engelhard De Meern (now BASF), and with TNO Automotive, Shell, E.P. Controls and IPCOS.
Dr Karen Scholz | alfa
The Future of Mobility: tomorrow’s ways of getting from A to B
07.09.2017 | Fraunhofer-Institut für Angewandte Informationstechnik FIT
ShAPEing the future of magnesium car parts
23.08.2017 | DOE/Pacific Northwest National Laboratory
Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.
The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...
Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...
Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!
When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...
For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.
Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...
MBM ScienceBridge GmbH successfully negotiated a license agreement between University Medical Center Göttingen (UMG) and the biotech company Tissue Systems Holding GmbH about commercial use of a multi-well tissue plate for automated and reliable tissue engineering & drug testing.
MBM ScienceBridge GmbH successfully negotiated a license agreement between University Medical Center Göttingen (UMG) and the biotech company Tissue Systems...
19.09.2017 | Event News
12.09.2017 | Event News
06.09.2017 | Event News
21.09.2017 | Physics and Astronomy
21.09.2017 | Life Sciences
21.09.2017 | Health and Medicine