Process produces hydrogen at lower temperatures
22 May 2013
Duke University has produced hydrogen with less than 0.002% of carbon monoxide.
The Duke engineers, using a new catalytic approach, have shown that they can reduce carbon monoxide levels to nearly zero in the presence of hydrogen and the harmless byproducts of carbon dioxide and water.
They also demonstrated that they could produce hydrogen by reforming fuel at much lower temperatures than conventional methods, which makes it a more practical option.
“We were able through our system to consistently produce hydrogen with less than 0.002% (20 parts per million) of carbon monoxide,” Titilayo Shodiya, a graduate student at Duke.
The Duke researchers achieved these levels by switching the recipe for the nanoparticles used as catalysts for the reactions to oxidise carbon monoxide in hydrogen-rich gases.
Traditional methods of cleaning hydrogen, which are not nearly as efficient as this new approach, also involve gold-iron oxide nanoparticles as the catalyst, the researchers said.
“It had been assumed that the iron oxide nanoparticles were only ‘scaffolds’ holding the gold nanoparticles together, and that the gold was responsible for the chemical reactions,” Sodiya said.
“However, we found that increasing the surface area of the iron oxide dramatically increased the catalytic activity of the gold.”
One of the newest approaches to producing renewable energy is the use of biomass-derived alcohol-based sources, such as methanol. When methanol is treated with steam, or reformed, it creates a hydrogen-rich mixture that can be used in fuel cells.
The main problem with this approach is that it also produces carbon monoxide, which is not only toxic to life, but also quickly damages the catalyst on fuel cell membranes.
The researchers ran the reaction for more than 200 hours and found no reduction in the ability of the catalyst to reduce the amount of carbon monoxide in the hydrogen gas.
