How to churn out a ‘greener’ margarine
MCGILL (CAN) — A new technique replaces heavy metals with iron as a catalyst for hydrogenation, a process used to make pharmaceuticals and foods like margarine.
Hydrogenation typically involves the use of heavy metals, such as palladium or platinum, to catalyze the chemical reaction. While these metals are very efficient catalysts, they are also non-renewable, costly, and subject to sharp price fluctuations on international markets.
Because these metals are also toxic, even in small quantities, they also raise environmental and safety concerns.
Pharmaceutical companies, for example, must use expensive purification methods to limit residual levels of these elements in pharmaceutical products. Iron, by contrast, is both naturally abundant and far less toxic than heavy metals.
Previous work by other researchers has shown that iron nanoparticles—tiny pieces of metallic iron—can be used to activate the hydrogenation reaction. Iron, however, has a well-known drawback: it rusts in the presence of oxygen or water. When rusted, iron nanoparticles stop acting as hydrogenation catalysts. This problem, which occurs with so much as trace quantities of water, has prevented iron nanoparticles from being used in industry.
In research published in the journal Green Chemistry, scientists report that they have found a way to overcome this limitation, making iron an active catalyst in water-ethanol mixtures containing up to 90 percent water.
The key to this new method is to produce the particles directly inside a polymer matrix, composed of amphiphilic polymers based on polystyrene and polyethylene glycol. The polymer acts as a wrapping film that protects the iron surface from rusting in the presence of water, while allowing the reactants to reach the water and react.
This innovation enabled the researchers to use iron nanoparticles as catalyst in a flow system, raising the possibility that iron could be used to replace platinum-series metals for hydrogenation under industrial conditions.
“Our research is now focused on achieving a better understanding of how the polymers are protecting the surface of the iron from water, while at the same time allowing the iron to interact with the substrate,” says Audrey Moores, an assistant professor of chemistry at McGill University and co-corresponding author of the paper.
“The approach we have developed through this collaboration could lead to more sustainable industrial processes,” says Professor Yasuhiro Uozumi of RIKEN and the Institute for Molecular Science in Japan. “This technique provides a system in which the reaction can happen over and over with the same small amount of a catalytic material, and it enables it to take place in almost pure water—the green solvent par excellence.”
The Natural Sciences and Engineering Research Council of Canada, the Canada Foundation for Innovation, the Canada Research Chairs, the Fonds de recherche du Québec—Nature et technologies, the Riken-McGill Fund, the Japan Society for the Promotion of Science, and the Japan Science and Technology Agency funded the research.
Source: McGill University
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