Skip to comments.Make methane while the sun shines - Nanotubes help turn carbon dioxide and water into...
Posted on 02/09/2009 3:59:13 PM PST by neverdem
Nanotubes help turn carbon dioxide and water into natural gas.
Researchers have used sunlight to convert carbon dioxide and water vapour into a range of fuels faster than ever before, thanks to a nanotube catalyst.
Materials scientist Craig Grimes and his colleagues at Pennsylvania State University in University Park have used hollow titania (titanium dioxide) nanotubes around 135 nanometres wide and a tenth of a millimetre long to catalyse the reaction. Scientists have used titania nanoparticles to speed up this process before, but Grimes and his colleagues were able to generate hydrocarbons around 20 times faster than that achieved in previous studies, thanks to some clever chemistry.
The researchers added a little nitrogen to their nanotubes and loaded copper and platinum nanoparticles onto the surfaces. On its own, titania works best as a catalyst for this reaction in ultraviolet light. But adding nitrogen and copper to the mix shifts the preference of the titania tubes to visible light, Grimes says. And the copper and platinum nanoparticles are thought to speed up the latter stages of the reaction.
The reaction itself also takes place inside the nanotubes, which are hollow and have a large internal surface area thanks to their thin 20-nanometer-thick walls.
The researchers filled steel tubes with carbon dioxide and water vapour, covered the end of the chambers with a film of their nanotubes, and capped the containers with a quartz window to let light in. The closed chambers were then set outside on on the university campus on sunny days from July to September 2008.
When light falls on the nanotubes, they release energetic charge carriers, which split the water molecules inside them into two reactive components â hydroxide radicals and hydrogen ions. The hydrogen ions combine to form hydrogen gas. The researchers don't yet understand exactly what happens next, but they think that the carbon dioxide also splits to form oxygen and carbon monoxide, which then reacts with gaseous hydrogen to form methane and water.
The devices generated roughly 160 microlitres of the hydrocarbons per hour per gram of their titania nanotubes, a rate at least 20 times higher than in previous studies done with ultraviolet light. The findings are published online in the journal Nano Letters1.
Physical chemist Michael GrÃ¤tzel at the Federal Polytechnic School of Lausanne in Switzerland says that the results "are fundamental work that shows that nanotubes might get you a better conversion efficiency than prior approaches". He points out that the efficiency of the catalyst is still quite low, but is optimistic that further work can improve it.
"This is clearly very nice work, with some excellent science," says electrochemist John Turner at the National Renewable Energy Laboratory in Golden, Colorado. But he cautions that other solutions for dealing with carbon dioxide may prove more viable.
Commercial processes are already available that use carbon dioxide to make a mixture called syngas, which can then be converted to liquid hydrocarbons in a process that can run continuously. But with the new nanotube devices, the chambers would have to be replenished with carbon dioxide and water from time to time to keep the reaction going. "Why do you want to take a nice continuous process and turn it into an intermittent one by coupling it with solar [energy]?," he asks.
But the researchers argue that their process could be made continuous if carbon dioxide and water vapour could be passed through the nanotube film and the methane fuel collected from the other side. Even with their current nanotubes, Grimes calculates that a reflector that concentrates sunlight on a square metre of the nanotube film could yield 500 litres of methane over the course of eight hours.
Grimes, however, agrees that the production rates are still quite low â "to date we are not going to save mankind", he says. But he hopes that depositing copper nanoparticles more evenly onto the surfaces of the nanotubes and making other improvements will help boost their conversion rates by a factor of several thousand. "I believe this can be commercially practical with a given concentrated carbon dioxide source such as coal plant," he says.
IIRC, methane is a component of natural gas which also other alkanes, e.g. ethane, propane, butane, etc., until they are liquid at ambient temperature such as octane.
I thought Obama wanted to tax hogs & cows for producing methane.
Well yes, but can’t you just pile up some grass clippings and leave them in the sun? Around here we have swamps that do the heavy lifting.
H#}} just put a giant capture bag over DC and there would be enough gas caught to power the world!
To get 1 liter/hr, you would need 6 Kg of the stuff, spread out in a thin coating (so sunlight could get to it). The guy's angling for a grant. Current solar power is much more efficient.
“Get in on the ground! Only one dollah, fokes! One dollah buys you a share!”
Well dang...I reckon I am filled with them nano tube thingies.
This is abiotic - requiring no bacteria or algae to form hydrocarbons.
Most of the hydrocarbons that are recovered from beneath the earth’s crust are NOT “dionsaur soup”, regardless of popular misconceptions. A good many of them are formed by the catalyst acting on methane, and the reaction under heat and pressure of carbom dioxide and water molecules.
Methane was a large component of our primorial atmosphere, as was ammonia and carbon dioxide. Water existed only as vapor, because of the relative heat of the planet at the time. There was NO free oxygen or nitrogen, because of the very high reactivity of oxygen, and until the planet cooled sufficiently, and a very basic form of life developed that could free the oxygen from carbon dioxide, oxygen was not generated in sufficient quantities to affect the balance of the atmosphere. Once it did, of course, almost all anaerobic life forms were driven into water depths and beneath strata of earth to escape its effects. There is still anaerobic life today, but exposure to oxygen causes its almost immediate expiration.
To the purists, OXYGEN is the atmospheric pollutant, not carbon dioxide.
Methane is the simplest hydrocarbon conversion gas, used in the conversion of many hydrocarbons to others. For instance, coal gasification and coal to liquids conversion -- and many other refinery processes.
Oxygen, better not beat up on it too much, as we need it for our own selfish cellular respiration. Although if it weren't for oxidizers, where would we be.
Much of the info was shelved when we brought their rocket pals over.
So shelving the process was one of costs, it cost about $40 a barrel equivalent to convert coal to liquid transport fuel. About what price oil is today.
What is interesting is while we are out jousting with windmills, the USA is literally the Saudi Arabia of coal. We could easily establish a floor price for oil at the conversion costs of coal. The real question is why don't we? well, OK, I know the freaks running the country wouldn't allow it.
But conversion is cost based, when not convenience based.
Obama's beloved Indonesia is the latest to invest in a major coal to liquids plant and they said that $25 a barrel was achievable. I would have to see to believe.
By "shelved" I mean "controlled" in a subrosa fashion.
Harry Reid: “nancy we got to figure out how to stimulate it”
Nancy: “yes stimulate it and then tax it”
Oxygen is a caustic poisonous gas.
...split the water molecules inside them into two reactive components -- hydroxide radicals and hydrogen ions. The hydrogen ions combine to form hydrogen gas. The researchers don't yet understand exactly what happens next, but they think that the carbon dioxide also splits to form oxygen and carbon monoxide, which then reacts with gaseous hydrogen to form methane and water. The devices generated roughly 160 microlitres of the hydrocarbons per hour per gram of their titania nanotubes...Titania... that sounds nice and cheap...
added a little nitrogen to their nanotubes and loaded copper and platinum nanoparticles onto the surfaces.Ah! Probably the platinum.