In the journal Angewandte Chemie, Japanese researchers have now introduced a new catalytic system for the fast and complete degradation of ethylene. This system could keep the air in warehouses ethylene-free, keeping perishable products fresh longer.
Ethylene is not just a feedstock for the chemical industry; it also acts as a plant hormone, regulating many physiological processes, such as the ripening of fruits and the blooming and wilting of flowers. A familiar example of this is bananas left in a plastic bag, which ripen much faster than those left out. This type of acceleration of ripening even happens in a refrigerator at temperatures around 0 °C.
It is thus very important for wholesalers to remove traces of ethylene from warehouses and cold-storage facilities where fruit, vegetables, and flowers are stored. Previous biotechnological removal methods are expensive, complex, or ineffective. The search for a suitable catalyst for the oxidation of ethylene has also not been very successful. The stumbling block has been the low temperature at which the process must work.
Atsushi Fukuoka and his co-workers at Hokkaido University tested different metals in combination with a variety of support materials to develop an effective catalyst. They met with success: Platinum nanoparticles on a support made of special mesoporous silicon dioxide (MCM-41) demonstrated very high activity in the oxidation of ethylene at 0 to 20 °C. At an ethylene concentration of 50 ppm, over 99.8 % conversion was obtained at 0 °C, a previously unattained level that remains steady over longer periods and after multiple uses.
The catalyst is made by stirring the support with an aqueous solution of a platinum salt for 18 hours. The support is then dried and heated first under oxygen and then under hydrogen. After this process, the large pores of the silicon dioxide material contain platinum particles with a size of about 2.4 nm. This particle size, as well as the effect of the silica, seem to be particularly favorable for the reaction.
It is proposed that ethylene (C2H4) and oxygen initially react rapidly on this catalyst to form formaldehyde (HCHO), which is adsorbed onto the platinum and then primarily degraded to carbon monoxide (CO) and hydrogen species that in turn react with oxygen species to make carbon dioxide and water. A small amount of formic acid is formed as a byproduct. The especially high activity of the catalyst results from the facile oxidation of CO to CO2 that occurs at platinum on silicon dioxide supports. The precise details of the reaction mechanism are currently under investigation.
Author: Atsushi Fukuoka, Hokkaido University (Japan), http://www.cat.hokudai.ac.jp/fukuoka/english.html
Title: Low-Temperature Oxidation of Ethylene over Platinum Nanoparticles Supported on Mesoporous Silica
Angewandte Chemie International Edition, Permalink to the article: http://dx.doi.org/10.1002/anie.201300496
Individual Receptors Caught at Work
19.10.2017 | Julius-Maximilians-Universität Würzburg
Rapid environmental change makes species more vulnerable to extinction
19.10.2017 | Universität Zürich
University of Maryland researchers contribute to historic detection of gravitational waves and light created by event
On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...
Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.
Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....
Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).
When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...
Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.
How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...
Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.
It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...
17.10.2017 | Event News
10.10.2017 | Event News
10.10.2017 | Event News
19.10.2017 | Materials Sciences
19.10.2017 | Materials Sciences
19.10.2017 | Physics and Astronomy