New method for producing clean hydrogen

May 21, 2013
This is Nico Hotz, left, and Titilayo Shodiya. Credit: Duke University

Duke University engineers have developed a novel method for producing clean hydrogen, which could prove essential to weaning society off of fossil fuels and their environmental implications.

While hydrogen is ubiquitous in the environment, producing and collecting for transportation and industrial uses is expensive and complicated. Just as importantly, a byproduct of most current methods of is carbon monoxide, which is toxic to humans and animals.

The Duke engineers, using a new catalytic approach, have shown in the laboratory 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.

Catalysts are agents added to promote chemical reactions. In this case, the catalysts were nanoparticle combinations of gold and iron oxide (rust), but not in the traditional sense. Current methods depend on gold nanoparticles' ability to drive the process as the sole catalyst, while the Duke researchers made both the iron oxide and the gold the focus of the catalytic process.

The study appears online in the Journal of Catalysis.

"Our ultimate goal is to be able to produce hydrogen for use in fuel cells," said Titilayo "Titi" Shodiya, a graduate student working in the laboratory of senior researcher Nico Hotz, assistant professor of mechanical engineering and materials science at Duke's Pratt School of Engineering. "Everyone is interested in sustainable and non-polluting ways of producing useful energy without fossil fuels," said Shodiya, the paper's first author.

Fuel cells produce electricity through chemical reactions, most commonly involving hydrogen. Also, many require hydrogen as a chemical reagent and vehicles are beginning to use hydrogen as a primary .

"We were able through our system to consistently produce hydrogen with less than 0.002 percent (20 parts per million) of carbon monoxide," Shodiya said.

The Duke researchers achieved these levels by switching the recipe for the nanoparticles used as catalysts for the reactions to oxidize 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 ," 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 that are crucial to the functioning of a ," Hotz said. "It doesn't take much carbon monoxide to ruin these 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 in the gas.

"The mechanism for this is not exactly understood yet. However, while current thinking is that the size of the gold particles is key, we believe the emphasis of further research should focus on 's role in the process," Shodiya said.

Explore further: Incorporation of DOPA into engineered mussel glue proteins

More information: "Novel nano-scale Au/alpha-Fe2O3 catalyst for the preferential oxidation of CO in biofuel reformate gas," Titilayo Shodiya, et. al, Journal of Catalysis, DOI 10.1016/j.cat.2012.12.027 , http://www.sciencedirect.com/science/article/pii/S0021951712004204

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PermAlex
4 / 5 (2) May 21, 2013
How come hydrogen is seen as the solution to fossil fuels? The production process clearly emits carbon-dioxide, which is the main problem. The fact they suggest using bio-ethanol is a very unsustainable in my opinion; first, because methanol is made from food crops (see biobased economy) and second, cars can be made to run on ethanol, saving the entire production process.

Nevertheless a great progress in nano-tech!
PPihkala
5 / 5 (3) May 21, 2013
I also agree that bio-ethanol is generally not a good substitute for fossil fuels, unless it is manufactured from waste material. Growing crops for ethanol use too much water, which should already be more expensive so that people would not waste it.
ValeriaT
2.8 / 5 (8) May 21, 2013
Growing crops for ethanol use too much water
In addition, without continuous application of fertilizers the soil will change into desert fast, because the harvest of biofuels removes the minerals from soil. The biofuels aren't sustainable at all from this perspective.
Soylent_Grin
not rated yet May 21, 2013
The production process clearly emits carbon-dioxide, which is the main problem.

It doesn't say how much in relation to current burning of hydrocarbons.
Additionally, the problem with burning fuel is that the CO2 is released when the fuel is consumed, meaning far less ability to capture and contain it from going into the atmosphere.
With this, the CO2 is a byproduct of *making* the fuel, not consuming it. Which means that a sequester can be easily added at the creation stage.
italba
1 / 5 (2) May 21, 2013
A traditional fuel reformed to hydrogen for a fuel cell could give more energy than the same fuel burned in a diesel engine, due to the higher efficiency of the fuel cell. So, if you don't want to (or can't) use the residual heat, fuel cells can reduce the amount of CO2 per energy unit.
Sanescience
3 / 5 (2) May 21, 2013
OMG people.

How come hydrogen is seen as the solution to fossil fuels? The production process clearly emits carbon-dioxide

In general case molecular hydrogen from water results in release of oxygen. H2O -> H2 + O. If further reactions incorporate carbon from CO2 atmosphere into a hydrocarbon structure the result is to release more oxygen. When burned the release of H2O and CO2 match those taken from the environment, so result in no net increase of CO2 in the atmosphere.

In addition, without continuous application of fertilizers the soil will change into desert fast, because the harvest of biofuels removes the minerals from soil. The biofuels aren't sustainable at all from this perspective.

That's right, thousands of years of crop harvesting has turned all the worlds fields into desert. Oh wait...

These issues aside, for reasons of efficiency, molecular hydrogen is not the best fit for transportation energy.

antialias_physorg
1 / 5 (3) May 22, 2013
These issues aside, for reasons of efficiency, molecular hydrogen is not the best fit for transportation energy.

It's usually a mixed bag of considerations when evaluating whether a fuel is sensible or not.

For example hydrogen may not be the most efficient - but in cities you have also the pollution aspects (where hydrogen reigns supreme).
Plus the prouction of hydrogen can occur very decentralized - unlike fossil fuels - which opens up all kinds of advantages in terms of usage (storage of excess energy, less transportation cost of energy carriers, private production for private use, .. )

Some communities already have hydrogen busses running and are pretty happy with the results. So I guess you always have to consider the entire environment/ecosystem and not just the efficiency factor when considering hydrogen as an alternative.
NikFromNYC
1.6 / 5 (7) May 22, 2013
Love, don't hate, plant food.

Shame on you, Phys.org, for trashing science with celebration of green cultism that still leads to scientific fraud being celebrated by those who still trust you to be sincere and honest instead of fascist. That you have failed to come clean at this late stage of madness marks you forever as masters of folly.
italba
1.3 / 5 (4) May 22, 2013
NikFromNYC: Don't worry, stay quiet, the doctors will arrive for you very soon...
Mannstein
not rated yet May 23, 2013
This report says nothing about bio-ethanol. It talks about bio-methanol. Big difference.
Mike_Massen
1 / 5 (1) May 25, 2013
antialias_physorg sadly fell for propaganda
Some communities already have hydrogen busses running and are pretty happy with the results. So I guess you always have to consider the entire environment/ecosystem and not just the efficiency factor when considering hydrogen as an alternative.
*All* H2 bus trials are wildly expensive and produce far more CO2 than petrol for the *equivalent* distance travelled...!

We had this trialled in Perth, Western Australia. The busses ended up costing over > 1million $A and could only go 80 kms between fills. BP were doubtless rubbing their hands with glee when the government consumed the H2 they would otherwise flare off from their petrol refinery as it costs way too much and too dangerous to even store !