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 Magic number colloidal clusters
13.12.2018 | Friedrich-Alexander-Universität Erlangen-Nürnberg

nachricht Record levels of mercury released by thawing permafrost in Canadian Arctic
13.12.2018 | University of Alberta

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: An energy-efficient way to stay warm: Sew high-tech heating patches to your clothes

Personal patches could reduce energy waste in buildings, Rutgers-led study says

What if, instead of turning up the thermostat, you could warm up with high-tech, flexible patches sewn into your clothes - while significantly reducing your...

Im Focus: Lethal combination: Drug cocktail turns off the juice to cancer cells

A widely used diabetes medication combined with an antihypertensive drug specifically inhibits tumor growth – this was discovered by researchers from the University of Basel’s Biozentrum two years ago. In a follow-up study, recently published in “Cell Reports”, the scientists report that this drug cocktail induces cancer cell death by switching off their energy supply.

The widely used anti-diabetes drug metformin not only reduces blood sugar but also has an anti-cancer effect. However, the metformin dose commonly used in the...

Im Focus: New Foldable Drone Flies through Narrow Holes in Rescue Missions

A research team from the University of Zurich has developed a new drone that can retract its propeller arms in flight and make itself small to fit through narrow gaps and holes. This is particularly useful when searching for victims of natural disasters.

Inspecting a damaged building after an earthquake or during a fire is exactly the kind of job that human rescuers would like drones to do for them. A flying...

Im Focus: Topological material switched off and on for the first time

Key advance for future topological transistors

Over the last decade, there has been much excitement about the discovery, recognised by the Nobel Prize in Physics only two years ago, that there are two types...

Im Focus: Researchers develop method to transfer entire 2D circuits to any smooth surface

What if a sensor sensing a thing could be part of the thing itself? Rice University engineers believe they have a two-dimensional solution to do just that.

Rice engineers led by materials scientists Pulickel Ajayan and Jun Lou have developed a method to make atom-flat sensors that seamlessly integrate with devices...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

ICTM Conference 2019: Digitization emerges as an engineering trend for turbomachinery construction

12.12.2018 | Event News

New Plastics Economy Investor Forum - Meeting Point for Innovations

10.12.2018 | Event News

EGU 2019 meeting: Media registration now open

06.12.2018 | Event News

 
Latest News

Magic number colloidal clusters

13.12.2018 | Life Sciences

UNLV study unlocks clues to how planets form

13.12.2018 | Physics and Astronomy

Live from the ocean research vessel Atlantis

13.12.2018 | Earth Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>