Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Success in Development of Exhaust Gas Catalyst with Thermal Agglomeration Resistance 10x Higher than Conventional Materials

10.11.2010
This dramatic improvement in thermal agglomeration resistance opens the road to a large reduction in the amount of rare metals used in exhaust gas purification technologies.

Opening the Road to Reduced Use of Rare Metals

A research team headed by Dr. Hideki Abe, Senior Researcher of the Advanced Electronic Materials Center and Dr. Katsuhiko Ariga, Principal Investigator of the International Center for Materials Nanoarchitectonics (MANA), National Institute for Materials Science (President: Sukekatsu Ushioda) developed an exhaust gas catalyst material with approximately 10 times greater thermal agglomeration resistance than conventional materials. This dramatic improvement in thermal agglomeration resistance opens the road to a large reduction in the amount of rare metals used in exhaust gas purification technologies.

Environmental and energy technologies, represented by automotive exhaust gas purification, (1) are necessary and indispensible for human society in the 21st century for satisfying both abundant energy supplies and safe and healthy life. Metal catalysts,2 which are the most critical element materials in environmental and energy technologies, are confronted with the problem of thermal agglomeration, in which the catalyst loses its activity as a result of bonding/fusion of the catalyst due to heat and the accompanying reduction in the number of catalytic active sites.3 As catalytic active sites of metal catalysts, mainly platinum, palladium, rhodium,4 and other rare metals5 are used. To compensate for the reduction in catalytic activity caused by thermal agglomeration, the current technologies unavoidable require consumption of large amounts of rare metals, as there is no other method of introducing a large excess of active sites in the catalyst. Therefore, in this research, the NIMS team developed a metal catalyst with high resistance to thermal agglomeration by controlling the topology6 of the material at the nano-scale, which is completely different from the conventional approach.

The developed material, called gMetallic Cellh , consists of metal spheres with a cavity approximately 1/100mm in diameter, which is surrounded by a thin cell wall containing pores (channels) 1/1000mm in diameter that enable transmission of substances and energy to and from the outer world. Because gMetallic Cellh has a special topology by which the catalytic active site in the cell is protected by the cell wall, it demonstrates excellent long-term catalytic properties, even under high temperature conditions in which ordinary catalyst materials would lose their activity due to thermal agglomeration.

Metallic Cell is synthesized by precipitating a platinum film on the surface of commercially-available polystyrene powder by chemical reduction in an alcohol solution at normal temperature and pressure, followed by heating to 500‹C to vaporize the polystyrene. Accompanying vaporization of the polystyrene, the hollow topology is formed and pores through which the polystyrene gas escapes are opened in the platinum film, resulting in natural formation of the unique morphology of Metallic Cell shown in Fig. 1. The method used to synthesize Metallic Cell is extremely simple and can be applied not only to platinum, as described here, but also to a number of other metals which display catalytic activity, beginning with rhodium, which shows high activity in NOx purification. The applications of Metallic Cell are not limited to exhaust gas purification technology. Taking advantage of its excellent heat resistance and high scalability, a large reduction in the amount of rare metals used in many environmental and energy technologies is also possible, beginning with fuel cell technology.(7)

Reference Diagram
Automotive exhaust gas purification performance of Metallic Cell (red line in figure). Due to its special topology, Metallic Cell demonstrates heat resistance characteristics greatly exceeding those of the conventional catalyst materials (blue and black lines in figure).

Notes

1. Automotive exhaust gas purification: Automobile engines emit highly concentrated toxic gases, beginning with carbon monoxide and nitrogen oxides (NOx) which are harmful to the human body. When the exhaust gases from engines are released into the atmosphere, these toxic gases must be removed and purified by some method. Exhaust gas purification using metal catalysts is a representative method.

2. Metal catalyst: Generally indicates solid catalysts in which mainly transition metals are used as the material. Metal catalysts are used in important industrial applications, such as purification of exhaust gas from automobiles and power plants, desulfurization of petroleum, etc.

3. Catalytic active site: Indicates the atoms which play the main role in the catalytic reaction, among the atoms comprising the surface of a metal catalyst; these atoms are called catalytic active sites. In general, the activity of a catalytic material is high in proportion to the number of catalytic active sites per unit of weight.

4. Rhodium (Rh): A transition metal element located directly below cobalt in the Periodic Table; atomic number 45. Rh demonstrates high catalytic activity for NOx in exhaust gas purification. Production is small (approximately 10 tons/year), and Rh is also known as the most expensive of the noble metals.

5. Rare metal: General term for metal elements which are produced in small amounts and have a small distribution scale in the market, in contrast to base metals such as iron, copper, aluminum, zinc, and lead. The rare metals occupy an extremely important position as functional materials, including, for example, noble metal elements (platinum, palladium, rhodium, etc.), which are indispensible in exhaust gas purification technology, and rare earths, which are indispensible in high coercivity permanent magnets. Because the distribution of these mineral resources is uneven, it is also known that supplies and prices are easily affected by the political conditions in countries which possess these resources.

6. Topology: Word which expresses the 3-dimensional shape of a body or image in terms of phase geometry.

7. Fuel cell: Device which electrochemically burns small molecules such as hydrogen, methanol, etc. and supplies the charge transfer generated accompanying this reaction for use outside the reaction in the form of electricity. Fuel cells are a new technology which has attracted intense interest as a next-generation energy source.

Acknowledgement
These research results were achieved with the financial support of the World Premier International Research Center Initiative (WPI) of Japanfs Ministry of Education, Culture, Sports, Science and Technology (MEXT).

For more detail

Hideki Abe
Advanced Electronic Materials Center
National Institute for Materials Science
TEL: +81-29-859-2732
E-MailFABE.Hideki@nims.go.jp
Katsuhiko Ariga
International Research Center for Materials Nanoarchitectonics (MANA)
National Institute for Materials Science
TEL: +81-29-860-4597
E-MailFARIGA.Katsuhiko@nims.go.jp
For general inquiry
Public Relations Office, NIMS
TEL:+81-29-859-2026
FAX:+81-29-859-2017
E-MailFpr@nims.go.jp

Mikiko Tanifuji | Research asia research news
Further information:
http://www.nims.go.jp/eng/news/press/2010/10/p201010050.html
http://www.researchsea.com

More articles from Materials Sciences:

nachricht Getting closer to porous, light-responsive materials
26.07.2017 | Kyoto University

nachricht Multitasking monolayers
25.07.2017 | Vanderbilt University

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Carbon Nanotubes Turn Electrical Current into Light-emitting Quasi-particles

Strong light-matter coupling in these semiconducting tubes may hold the key to electrically pumped lasers

Light-matter quasi-particles can be generated electrically in semiconducting carbon nanotubes. Material scientists and physicists from Heidelberg University...

Im Focus: Flexible proximity sensor creates smart surfaces

Fraunhofer IPA has developed a proximity sensor made from silicone and carbon nanotubes (CNT) which detects objects and determines their position. The materials and printing process used mean that the sensor is extremely flexible, economical and can be used for large surfaces. Industry and research partners can use and further develop this innovation straight away.

At first glance, the proximity sensor appears to be nothing special: a thin, elastic layer of silicone onto which black square surfaces are printed, but these...

Im Focus: 3-D scanning with water

3-D shape acquisition using water displacement as the shape sensor for the reconstruction of complex objects

A global team of computer scientists and engineers have developed an innovative technique that more completely reconstructs challenging 3D objects. An ancient...

Im Focus: Manipulating Electron Spins Without Loss of Information

Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.

For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...

Im Focus: The proton precisely weighted

What is the mass of a proton? Scientists from Germany and Japan successfully did an important step towards the most exact knowledge of this fundamental constant. By means of precision measurements on a single proton, they could improve the precision by a factor of three and also correct the existing value.

To determine the mass of a single proton still more accurate – a group of physicists led by Klaus Blaum and Sven Sturm of the Max Planck Institute for Nuclear...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

Closing the Sustainability Circle: Protection of Food with Biobased Materials

21.07.2017 | Event News

»We are bringing Additive Manufacturing to SMEs«

19.07.2017 | Event News

 
Latest News

CCNY physicists master unexplored electron property

26.07.2017 | Physics and Astronomy

Molecular microscopy illuminates molecular motor motion

26.07.2017 | Life Sciences

Large-Mouthed Fish Was Top Predator After Mass Extinction

26.07.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>