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
Researchers invent tiny, light-powered wires to modulate brain's electrical signals
21.02.2018 | University of Chicago
The “Holy Grail” of peptide chemistry: Making peptide active agents available orally
21.02.2018 | Technische Universität München
For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.
In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...
Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale
Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...
For photographers and scientists, lenses are lifesavers. They reflect and refract light, making possible the imaging systems that drive discovery through the microscope and preserve history through cameras.
But today's glass-based lenses are bulky and resist miniaturization. Next-generation technologies, such as ultrathin cameras or tiny microscopes, require...
Scientists from the University of Zurich have succeeded for the first time in tracking individual stem cells and their neuronal progeny over months within the intact adult brain. This study sheds light on how new neurons are produced throughout life.
The generation of new nerve cells was once thought to taper off at the end of embryonic development. However, recent research has shown that the adult brain...
Theoretical physicists propose to use negative interference to control heat flow in quantum devices. Study published in Physical Review Letters
Quantum computer parts are sensitive and need to be cooled to very low temperatures. Their tiny size makes them particularly susceptible to a temperature...
15.02.2018 | Event News
13.02.2018 | Event News
12.02.2018 | Event News
21.02.2018 | Life Sciences
21.02.2018 | Life Sciences
21.02.2018 | Materials Sciences