Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Catalysis discovery takes aim at NOx emissions

25.02.2008
PNNL researchers show how barium oxide anchors itself to exhaust treatment materials

A discovery in molecular chemistry may help remove a barrier to widespread use of diesel and other fuel-efficient "lean burn" vehicle engines. Researchers at the Department of Energy's Pacific Northwest National Laboratory have recorded the first observations of how certain catalyst materials used in emission control devices are constructed.

The PNNL team observed how barium oxide attaches itself to the surface of gamma-alumina. Barium oxide is a compound that absorbs toxic nitrogen oxide, commonly referred to as NOx, from tail-pipe emissions. Gamma alumina is a form of aluminum oxide that is used as a support for catalyst materials, such as barium oxide, that are the active ingredients in exhaust systems.

"The discovery is encouraging because understanding catalysts in molecular and atomic detail can directly identify new ways to improve them," said PNNL researcher Janos Szanyi. The manner in which barium oxide anchors onto alumina suggests the exact site where catalytic materials begin to form - and where they can be available to absorb NOx emissions.

Lean burn engines deliver up to 35 percent better fuel economy because they mix more air with gasoline than standard internal combustion engines. But the more efficient engines can't meet strict emissions standards because current aftertreatment devices don't effectively reduce NOx emissions. New catalysts are essential before the economic and environmental benefits of lean burn engines can be realized.

Alumina is a common and relatively inexpensive catalyst support material. Its surface structure, formation and thermal stability have been the subjects of much research, but the alumina particles are too small and poorly crystalline for traditional surface analysis. Researchers used the world's first 900-MHz nuclear magnetic resonance spectrometer to reveal the anchoring behavior. The instrument is located at the William R. Wiley Environmental Molecular Sciences Laboratory, a DOE national scientific user facility at PNNL.

Scientists know that the aluminum ions in alumina coordinate, or bond, to either four or six oxygen ions. When water is present, 10 to 15 percent of the aluminum ions on the surface bond to six oxygen ions: one underneath to the bulk of the alumina, four in a square on the surface and one on top to an oxygen ion in the water molecule.

Removing the water by heating leaves the aluminum ion with only five oxygen bonds. In this "penta-coordinated" state, the aluminum is open for bonding to the barium oxide. Results from the NMR spectrometer showed that the catalyst filled every available penta-coordinated site, atom-for-atom.

The team is now examining the interaction of gamma-alumina with other metal and metal oxide particles to determine if penta-coordinated aluminum ions are suitable bonding locations for other catalytic materials.

DOE's Office of Basic Energy Sciences, Division of Chemical Sciences funded the research, which was facilitated by the laboratory's Institute for Interfacial Catalysis.

PNNL is a DOE Office of Science national laboratory that solves complex problems in energy, national security and the environment, and advances scientific frontiers in the chemical, biological, materials, environmental and computational sciences. PNNL employs 4,000 staff, has a $750 million annual budget, and has been managed by Ohio-based Battelle since the lab's inception in 1965.

A portion of this research was conducted at the William R. Wiley Environmental Molecular Sciences Laboratory in Richland, Wash. EMSL is a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory.

Reference: Ja Hun Kwak, Jain Zhi Hu, Do Heui Kim, Janos Szanyi and Charles Peden. "Penta-coordinated Al3+ Ions as Preferential Nucleation Sites for BaO on ã-Al2O3." Journal of Catalysis 251(1):189-194. July 2007.

Contacts: Judith Graybeal, PNNL, (509) 375-4351

Judith Graybeal | EurekAlert!
Further information:
http://www.pnl.gov

More articles from Automotive Engineering:

nachricht 3D scans for the automotive industry
16.01.2017 | Julius-Maximilians-Universität Würzburg

nachricht Improvement of the operating range and increasing of the reliability of integrated circuits
09.11.2016 | Technologie Lizenz-Büro (TLB) der Baden-Württembergischen Hochschulen GmbH

All articles from Automotive Engineering >>>

The most recent press releases about innovation >>>

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

Im Focus: Wafer-thin Magnetic Materials Developed for Future Quantum Technologies

Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.

Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...

Im Focus: World's thinnest hologram paves path to new 3-D world

Nano-hologram paves way for integration of 3-D holography into everyday electronics

An Australian-Chinese research team has created the world's thinnest hologram, paving the way towards the integration of 3D holography into everyday...

Im Focus: Using graphene to create quantum bits

In the race to produce a quantum computer, a number of projects are seeking a way to create quantum bits -- or qubits -- that are stable, meaning they are not much affected by changes in their environment. This normally needs highly nonlinear non-dissipative elements capable of functioning at very low temperatures.

In pursuit of this goal, researchers at EPFL's Laboratory of Photonics and Quantum Measurements LPQM (STI/SB), have investigated a nonlinear graphene-based...

Im Focus: Bacteria harness the lotus effect to protect themselves

Biofilms: Researchers find the causes of water-repelling properties

Dental plaque and the viscous brown slime in drainpipes are two familiar examples of bacterial biofilms. Removing such bacterial depositions from surfaces is...

Im Focus: Hydrogen Bonds Directly Detected for the First Time

For the first time, scientists have succeeded in studying the strength of hydrogen bonds in a single molecule using an atomic force microscope. Researchers from the University of Basel’s Swiss Nanoscience Institute network have reported the results in the journal Science Advances.

Hydrogen is the most common element in the universe and is an integral part of almost all organic compounds. Molecules and sections of macromolecules are...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Dortmund MST Conference presents Individualized Healthcare Solutions with micro and nanotechnology

22.05.2017 | Event News

Innovation 4.0: Shaping a humane fourth industrial revolution

17.05.2017 | Event News

Media accreditation opens for historic year at European Health Forum Gastein

16.05.2017 | Event News

 
Latest News

New approach to revolutionize the production of molecular hydrogen

22.05.2017 | Materials Sciences

Scientists enlist engineered protein to battle the MERS virus

22.05.2017 | Life Sciences

Experts explain origins of topographic relief on Earth, Mars and Titan

22.05.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>