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Nanostructured Catalyst Produces Hydrogen from Ammonia

Ammonia

Researchers at Rutgers are exploring the use of an iridium-based nanostructured catalyst to extract hydrogen from ammonia for use in a fuel cell.

The research team found that iridium heated to temperatures above 300 ºC (approx. 600 ºF) in the presence of oxygen morphs into uniform arrays of nanosized pyramids.  The shape change is caused by the atomic forces from the adjacent oxygen atoms pulling the iridium atoms into a more tightly ordered crystalline state.

This pyramidal surface allows the ammonia molecules, themselves tetrahedral in shape, to nestle in nicely “like matching puzzle pieces.” This sets up the molecules to undergo complete and efficient decomposition.

Different annealing temperatures create different-sized facets on the pyramids, which affect how well the iridium catalyzes ammonia decomposition. The researchers are performing additional studies to characterize the process more completely.

Ammonia (NH3) is mostly manufactured through a catalytic industrial process using natural gas and air. The natural gas is reformed to create hydrogen gas, which is then processed to create the ammonia. The Rutgers process, in essence, undoes the initial manufacturing process.

Liquid ammonia could—in theory—be handled much like today’s gasoline and diesel fuel. Conceptually, a vehicle with a catalyst such as the one at Rutgers could produce hydrogen on-board for use in a fuel cell.

However, there are probably some practical barriers in the way. Ammonia is a hazardous substance that can cause bodily damage. Broad-based refueling might offer some challenges.

Second, although it is one of the most widely produced chemicals worldwide (140 million tonnes per year), 80% of that goes into the production of fertilizer. Any substantive use in transportation would require a major increase in chemical manufacturing capabilities.

All that aside, this work illustrates the potential in tailoring nanostructured metal surfaces on supported industrial catalysts to make new forms of catalysts that are more robust and selective.

A paper describing the research is to be published April 20 in the Journal of the American Chemical Society.

Comments

richard schumacher

Not to mention that a fuel system which depends on fossil hydrocarbons has no future, as it would contribute to atmospheric CO2 increase and global warming. This work is good science and applicable to agriculture but it's hard to see how it can help solve any transportation problem.

odograph

Ideally, we'd switch now to more efficient gasoline powered automobiles (including) hybrids. The next transition should probably be to natural gas (if supplies hold). Finally, as those are exhausted we'd go to hydrogen or electric - whichever made sense at that point in time.

It strikes me that electric has a place, despite research, subsidies, and hype for h2, simply because electric has worked and has been deployed.

But converting natural gas to ammonia and then ammonia to hydrogen gas seems too wasteful (energy loses in every conversion) when natural gas cars like the Honda GX are out there now!

Loudawg

Toshiba just announced a new battery that can recharge in one minute. I think this development has the potential to kill hydrogen/fuel cell cars. If your car is electric, you can plug it into an outlet, and be gone in a minute then what's the point of hydrogen? This convieniently coincides with the development of new superconductors that can one day carry electricity from a powerplant to your car with 100% efficiency.

Ken Sherman

I agree that battery technology will surpass other electrical supplies such as a fuel cells and hydrogen to drive it. I do think that you can probably put more BTUs in you tank as liquid ammonia than as gaseous hydrogen. Also note the current process they reference to produce ammonia does use natural gas as a hydrogen source, but there is a more efficient higher temperature catalytic technique to separate hydrogen and oxygen from water molecules. This just needs heat (nuclear powerplant reactor) and water to extract hydrogen. Now add the nitrogen molecule and you have ammonia. Seems like a cheaper way to help the farmers too!
All we need to solve most carbon and energy problems is a concerted effort by everyone to bring down the price on the current battery technologies and build more sources of clean, renewable electricity ( nukes and fuel reprocessing, wind, solar PV and heat, tidal, geothermal)
Let's always choose using costs and benefits as our primary reasons to do things.

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