Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Illinois Chemists Spray Their Way To Better Catalysts

12.07.2005


Scanning electron micrograph of molybdenum disulfide produced by ultrasonic spray pyrolysis. Large pores expose catalytically active edge sites. Photo credit: S.E. Skrabalak & K.S. Suslick, UIUC


Transmission electron micrograph of molybdenum disulfide produced by ultrasonic spray pyrolysis. Dark fringes emphasize the moly-sulfide crystal edges. Photo credit: S.E. Skrabalak & K.S. Suslick, UIUC


Using a technique called ultrasonic spray pyrolysis, researchers at the University of Illinois at Urbana-Champaign have created an improved catalyst for removing smelly sulfur-containing compounds from gasoline and other fossil fuels. The improved catalyst is a form of molybdenum disulfide, most commonly recognized as the black lubricant used to grease automobiles and machinery.

Molybdenum disulfide is made of long flat layers of molybdenum metal atoms sandwiched above and below by single atomic layers of sulfur. The interactions between sulfur-sulfur planes are weak, so they can easily slide past one another, providing excellent high-temperature lubrication.

Molybdenum disulfide’s other important commercial application is as a catalyst used by the petroleum industry to remove ecologically damaging sulfur-containing compounds in gasoline. When burned, these sulfur compounds cause the formation of acid rain.



"The flat planes of molybdenum disulfide that make it a good lubricant also decrease its ability to react with fuels to remove sulfur," said Ken Suslick, the Marvin T. Schmidt Professor of Chemistry at Illinois and a researcher at the Beckman Institute for Advanced Science and Technology. "This is because all the reactions necessary for sulfur removal occur on the edges of the long planes, and the bigger the planes, the less relative edge there is."

Using ultrasonic spray pyrolysis, Suslick and graduate student Sara Skrabalak discovered a way to make a highly porous network of molybdenum disulfide that preferentially exposes the catalytic edges. The researchers describe their work in a paper that has been accepted for publication in the Journal of the American Chemical Society, and posted on its Web site. Funding was provided by the National Science Foundation.

Using an ordinary household ultrasonic humidifier, Suslick and Skrabalak spray small droplets of precursor solutions into micron-sized droplets. The droplets are then carried by a gas stream into a furnace, where the solvent evaporates and dissolved substances react to form a product.

This spray-synthesis technique has allowed for the continuous, inexpensive production of spherical powders of varying composition. Research efforts are expanding this technique to the production of nanoparticles and industrially important catalysts.

The new form of molybdenum disulfide is made by spraying droplets of a water solution of ammonium tetrathiomolybdate (a molybdenum disulfide precursor) and colloidal silica (very fine sand). As the droplets are heated in the furnace, water evaporates and a molybdenum disulfide/silica composite is formed. The composite is then treated with hydrofluoric acid, which etches away the silica and leaves a network of molybdenum disulfide behind.

"This treatment leaves pores where the silica used to be and exposes the catalytically active edge of molybdenum disulfide," Suslick said. "Molybdenum disulfide is the standard industrial catalyst for hydrodesulfurization (the removal of sulfur from fuels using hydrogen), but this unique form of molybdenum disulfide has superior catalytic properties when compared to conventionally synthesized molybdenum disulfide."

In addition, the new spray-synthesis route to catalytic materials is simple, easily scaled-up, and can be adapted to other industrial materials.

James E. Kloeppel | University of Illinois
Further information:
http://www.uiuc.edu

More articles from Physics and Astronomy:

nachricht NASA detects solar flare pulses at Sun and Earth
17.11.2017 | NASA/Goddard Space Flight Center

nachricht Pluto's hydrocarbon haze keeps dwarf planet colder than expected
16.11.2017 | University of California - Santa Cruz

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

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

Im Focus: A “cosmic snake” reveals the structure of remote galaxies

The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.

Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...

Im Focus: Visual intelligence is not the same as IQ

Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.

That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...

Im Focus: Novel Nano-CT device creates high-resolution 3D-X-rays of tiny velvet worm legs

Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.

During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....

Im Focus: Researchers Develop Data Bus for Quantum Computer

The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.

Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...

Im Focus: Wrinkles give heat a jolt in pillared graphene

Rice University researchers test 3-D carbon nanostructures' thermal transport abilities

Pillared graphene would transfer heat better if the theoretical material had a few asymmetric junctions that caused wrinkles, according to Rice University...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Ecology Across Borders: International conference brings together 1,500 ecologists

15.11.2017 | Event News

Road into laboratory: Users discuss biaxial fatigue-testing for car and truck wheel

15.11.2017 | Event News

#Berlin5GWeek: The right network for Industry 4.0

30.10.2017 | Event News

 
Latest News

NASA detects solar flare pulses at Sun and Earth

17.11.2017 | Physics and Astronomy

NIST scientists discover how to switch liver cancer cell growth from 2-D to 3-D structures

17.11.2017 | Health and Medicine

The importance of biodiversity in forests could increase due to climate change

17.11.2017 | Studies and Analyses

VideoLinks
B2B-VideoLinks
More VideoLinks >>>