Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

The sweet smell of nano-success

30.01.2006


Cleaner method of making spices, perfumes moves one step closer to reality



Materials scientists at Lehigh University and catalyst chemists at Cardiff University have uncovered secrets of the "nanoworld" that promise to lead to cleaner methods of producing, among other things, spices and perfumes.

The materials scientists, headed by Christopher Kiely of Lehigh, have determined the structure of a type of gold-palladium nanoparticle, which is the active component of a new environmentally friendly catalyst that promotes the oxidation of primary alcohols to aldehydes.


The researchers reported their results Jan. 20 in Science magazine, one of the world’s top science journals. The article was titled "Solvent-free oxidation of primary alcohols to aldehydes using titania-supported gold-palladium catalysts."

The oxidation of primary alcohols to aldehydes is of fundamental importance to the chemical, pharmaceutical and perfume industries.

The oxidation of aromatic primary alcohols, such as vanillyl and cinnamyl alcohol, is of particular importance in the manufacture of perfumes and flavorings. Almost 95 percent of the worlds’ vanilla (vanillyl aldehyde) is synthetically manufactured.

Benzaldehyde is also a key intermediate in the production of many fine chemicals in the agrochemical and pharmaceutical industries.

Such oxidation reactions have always been performed using permanganates or chromates, but these reagents are expensive and have serious toxicity issues associated with them. This new catalyst, consisting of gold-palladium nanoparticles dispersed on a titanium oxide support, allows this reaction to take place using oxygen under mild solvent-free conditions.

The new catalyst system was developed by a group headed by Prof. Graham Hutchings at Cardiff University in the United Kingdom.

"Determining the structure of the gold-palladium nanoparticle will help us understand how this catalyst works at the atomic level," says Kiely, who directs the Nanocharacterization Laboratory at Lehigh University in Bethlehem, Pa.

"This will inevitably enable us to optimize its performance and will subsequently lead to the development of other gold-based catalysts."

Samples of the catalyst were studied by Andrew Herzing, a Ph.D. candidate in materials science and engineering in Lehigh’s Center for Advanced Materials and Nanotechnology (CAMN). Herzing used Lehigh’s VG HB 603 aberration-corrected scanning transmission electron microscope (STEM), which enables energy dispersive x-ray data to be collected from individual nanoparticles.

"Our aberration-corrected STEM is unique in that it has an extremely small and intense electron probe. It also has a very high collection efficiency for the x-rays generated," says Kiely.

The original microscope was purchased almost a decade ago but was fitted only last year with a spherical aberration corrector designed to overcome distortions in the lenses that focus the electron beam. This has led to a significant improvement in resolution.

"Before being fitted with the aberration corrector, this microscope held the world record for spatial resolution in x-ray elemental mapping at two nanometers (two billionths of a meter)," says Kiely.

"Now, with the aberration corrector, it achieves an elemental mapping resolution of half a nanometer, approximately the width of two atoms."

Even so, obtaining chemical information from the tiny gold-palladium particle is difficult because the x-ray signal from a palladium atom is far weaker than the signal from a gold atom. There are also signals from the titanium oxide support. Under normal circumstances, the palladium signal would be lost in the noise.

To overcome this, Masashi Watanabe, a research scientist in the CAMN, has developed software based on multivariate statistical analysis combined with a spectrum imaging technique. While scanning for a particular element, Watanabe’s software compares all the signals generated from an area and automatically identifies features in a particular signal dataset (in this case, a characteristic palladium X-ray signal).

Watanabe’s automated approach significantly reduces the amount of random noise both in the signal and background. While a similar methodology has been in use for some time, Watanabe’s program reduces the data analysis time from several hours to a few minutes.

Elemental maps collected from individual nanoparticles revealed that the palladium signal originates from a slightly larger spatial area than that of the corresponding gold signal. From this, Kiely’s team concluded that the nanoparticles have a core-shell structure in which a palladium-rich shell surrounds a gold-rich core.

Even though the outer shell is palladium rich, this gold-palladium catalyst significantly outperformed a similar catalyst comprised solely of palladium. It is proposed that the gold acts as an electron promoter for the palladium, thus enhancing the nanoparticle’s catalytic properties.

"Correlating a particular catalyst’s performance with detailed structural and compositional data consistently proves to be a powerful methodology for understanding catalytic reactions," says Kiely.

Kiely has been collaborating with Hutchings for more than 10 years. The Lehigh-Cardiff team published an article titled "Tuneable gold catalysts for selective hydrocarbon oxidation under mild conditions" in Nature magazine on Oct. 20.

Kurt Pfitzer | EurekAlert!
Further information:
http://www.lehigh.edu

More articles from Life Sciences:

nachricht Scientists uncover the role of a protein in production & survival of myelin-forming cells
19.07.2018 | Advanced Science Research Center, GC/CUNY

nachricht NYSCF researchers develop novel bioengineering technique for personalized bone grafts
18.07.2018 | New York Stem Cell Foundation

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Future electronic components to be printed like newspapers

A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.

The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...

Im Focus: First evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

A smart safe rechargeable zinc ion battery based on sol-gel transition electrolytes

20.07.2018 | Power and Electrical Engineering

Reversing cause and effect is no trouble for quantum computers

20.07.2018 | Information Technology

Princeton-UPenn research team finds physics treasure hidden in a wallpaper pattern

20.07.2018 | Materials Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>