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Derek Lowe The 2002 Model

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Derek Lowe, an Arkansan by birth, got his BA from Hendrix College and his PhD in organic chemistry from Duke before spending time in Germany on a Humboldt Fellowship on his post-doc. He's worked for several major pharmaceutical companies since 1989 on drug discovery projects against schizophrenia, Alzheimer's, diabetes, osteoporosis and other diseases. To contact Derek email him directly: Twitter: Dereklowe

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« Nobel Chemistry Odds | Main | Let Us Now Turn To the Example of Yo' Mama »

October 10, 2007

Ertl Wins: Down With Witchcraft

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Posted by Derek

As some had speculated, the Nobel in chemistry did take a turn toward physical chemistry this year, for the first time in some while. Gerhard Ertl has won for his work on reactions that take place on solid surfaces, an extremely important (and extremely difficult) field of research.

It’s hard because chemists and physicists have an easier time of it with bulk phases – all solid, liquid, or gas. When you start mixing them, or start trying to understand what happens where they meet, things get tricky. The border between two phases is very different from what’s on either side of it. The key zone is only a few atoms thick, and the interesting stuff there happens extremely quickly.

But some of the most important chemical reactions in the world take place down there. Take the Haber-Bosch process for producing ammonia – “Right,” I’m sure some readers of today’s newspaper are saying, “you take the Haber-Bosch process, whatever it is, and get it out of here.” But by making ammonia from nitrogen in the air, it led to (among other things) the invention of man-made fertilizers. That reaction has kept billions of people from starving to death, and kept huge swaths of wilderness from being turned into farmland. (Read up on Norman Borlaug if you haven’t already for more on this).

You can Haber-Bosch yourself some ammonia simply enough – just take iron powder, mix it with some drain cleaner (potassium hydroxide) and stir that up with some alumina and finely ground sand (silica). Heat it up to several hundred degrees and blow nitrogen and hydrogen across it; ammonia gas comes whiffing out the other end. Now, bacteria do this at room temperature in water, down around the roots of bean plants, but bacteria can do a lot of things we can’t do. For human civilization, this is a major achievement, because nitrogen does not want to do this reaction at all.

The industrial process was discovered in its earliest form nearly one hundred years ago, and was the subject of a Nobel all its own. But no one knew how it worked, which is a good example of how difficult surface interface work can be. You can see what has to happen eventually: the triple bond between two nitrogen atoms has to be broken and replaced by three bonds to hydrogen, whose own H-H bond is also broken. But that nitrogen triple is one of the strongest bonds in all of chemistry, so how is it breaking? Do the nitrogen molecules soak into the iron somehow, and if so, what does “soak in” mean on an atomic level, anyway? Do they sit on the surface, instead – and if they do, what keeps them there? Is that triple bond still in force when that happens, or has it started to break? If so, what on earth is strong enough on the surface of iron powder to do that? Where’s the hydrogen during all this, and how does its single bond get broken? What happens first, and why do you need the hydroxide and the other stuff? And so on.

Ertl and others had long studied hydrogen’s behavior on metal surfaces, while helping to figure out how catalytic hydrogenation works. (That was a reaction accurately described to me as an undergraduate in 1981 as “witchcraft”, and Ertl is one of the people who have helped to exorcise it). So they’d seen how hydrogen got broken into individual atoms and spread between iron atoms on the surface – the surprise for him and his co-workers was that nitrogen turned out to do the same thing, breaking that fearsome triple bond in the process. The biggest step in the whole mechanism happened very early. By running the reaction forward and in reverse (turning ammonia back into nitrogen and hydrogen, an otherwise perverse act for the most part), they were able to work out all the individual steps and the energies involved. Along the way, they figured out what the potassium hydroxide was doing in there, too (donating some key electrons to the iron atoms).

Observing this and other surface processes has pushed the limits of several spectroscopic techniques, such as Auger electron spectroscopy (AES), low-energy electron diffraction (LEED), various forms of photoelectron spectroscopy, and others. Ertl's work has been notable for using a wide variety of methods, since there's no one tool that can give you the answers to questions like these.

He and his associates have studied many other surface reactions, such as the sorts of things that go on in the catalytic converters in exhaust systems. Metal-surface reactions like this are crucial to industrial civilization, and their importance is, if anything, growing. If we're ever going to get fuel cells to work economically, use hydrogen as an energy medium, or do a better job cleaning up industrial wastes, we're going to be using such things. And keeping them in the category of witchcraft won't cut it. It never does. Congratulations to Gerhard Ertl!

Comments (23) + TrackBacks (0) | Category: Chemical News | Current Events


1. Wavefunction on October 10, 2007 11:22 AM writes...

God made solids, but surfaces were the work of the devil- Wolfgang Pauli

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2. Wavefunction on October 10, 2007 11:30 AM writes...

Haber-Bosch also shifted our food system from solar based to one based on fossil fuels with potentially disastrous consequences, as we are becoming all too aware of currently.

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3. Paul Dietz on October 10, 2007 2:25 PM writes...

It's fashionable to complain about the fossil fuel used in growing food, but Haber-Bosch doesn't require the hydrogen come from fossil fuels. Moreover, growing food in the industrial west only uses a few percent of total per capita energy demand. Last I checked, we used more energy cooking food than we did growing it.

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4. NH3 on October 10, 2007 2:33 PM writes...

I believe the sum total of fossil fuels used in manufacturing, processing, transporting, storing and using the fertiliser is substantial. That's one reason why the ethanol economy is now thought to be a bad idea at least the way it's being perceived, because you are putting in more energy from all these activities than you get out.

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5. Norman Yarvin on October 10, 2007 2:43 PM writes...

If you want to look for downsides of the Haber-Bosch process, you need only look to one of its first applications: letting the Germans continue fighting the First World War for four years, rather than having to fold after four months due to lack of nitrates.

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6. Walt on October 10, 2007 7:51 PM writes...

There is also an interesting historical account of the Haber-Bosch process in a book called "Hitler's Scientists." It also describes Hitler's apparent lack of appreciation of surface chemistry judging from his role in Haber's demise.

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7. Markus on October 10, 2007 8:08 PM writes...

As tough as that field appears to be, why did it take this long for him to be recognized?
On another topic: does anyone know a good prep. paper for making dipotassium azodicarboxylate?

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8. betsybounds on October 11, 2007 10:20 AM writes...

Well I'm no chemist, just a geologist with a very modest background in materials science, but I find all this fascinating.

I might add that, as a recently addicted Harry Potter fan, I was interested in Derek's following statement: ". . .catalytic hydrogenation works. (That was a reaction accurately described to me as an undergraduate in 1981 as "witchcraft", and Ertl is one of the people who have helped to exorcise it)" Of course, in the Harry Potter books, non-magical people are called "Muggles." Muggles spend huge amounts of time and energy at developing technology, which is essentially an attempt to approximate magic. While reading the Potter books, I was reminded of Clarke's Third Law: "Any sufficiently advanced technology will be indistinguishable from magic."

We're getting there, aren't we?

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9. Dr. Ellen on October 11, 2007 10:31 AM writes...

And any sufficiently domesticated magic will be indistinguishable from technology.

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10. Wavefunction on October 11, 2007 11:02 AM writes...

In the past men thought magic was medicine. Now it's the opposite.- Forgot who said it

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11. william on October 11, 2007 11:28 AM writes...

Wavefunction: The shift from solar energy to enhance agriculture enables us to feed the world without a 100% dependence on nature - thank goodness.

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12. Tatterdemalian on October 11, 2007 11:36 AM writes...

"I believe the sum total of fossil fuels used in manufacturing, processing, transporting, storing and using the fertiliser is substantial."

So are the sum total of fossil fuels used in harvesting, processing, transporting, storing, and using the "organic" (read: pre-industrial) alternatives. More so, in fact, because they were less concentrated, requiring more fuel to transport, store, and use, and very likely harvest and process as well.

Of course, environmentalists like to pretend something is free, as long as they approve of it. The failure of "sustainable" farming methods throughout Africa, forced upon them by EU trade restrictions, should serve as a warning to all who would let their policies be set by environmentalists.

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13. william on October 11, 2007 11:37 AM writes...

So the Germans used ammonia to prolong WWI. Dr. Chaim Weizmann's process to synthesize acetone via fermentation helped the British win the war, and eventually led to the establishment of the State of Israel. The atomic bomb led us to nuclear power. You can find bad in everything if you look hard enough.

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14. clazy on October 11, 2007 2:40 PM writes...

@Dr. Ellen--I can't decide whether that's tragic or not...

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15. JFred on October 11, 2007 5:05 PM writes...

What's so bad about the British winning WWII ?

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16. William on October 11, 2007 8:37 PM writes...


Actually it was WWI, and I was just trying to point out that there is good and bad in everything. And I'm glad the British won!

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17. coggieguy on October 11, 2007 11:24 PM writes...

Will the commenters who did not pass P Chem please check the PC BS at the door? Class is in session and (for the pre-meds) this will be on the test.

Bonus points - will those who object to modern fertilizer use voluntarily starve themselves (all the way)as an act of solidarity with Gaia? Must show work, start with coal tar and inorganic acids.

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18. william on October 12, 2007 9:35 AM writes...

coggieguy: Great point. I once worked at the largest coal chemical plant in the world. While coal tar itself is an obnoxious substance, it is the base for thousands of chemicals that have greatly benefited the human race.

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19. JSinger on October 12, 2007 10:31 AM writes...

Of course, in the Harry Potter books, non-magical people are called "Muggles." Muggles spend huge amounts of time and energy at developing technology, which is essentially an attempt to approximate magic.

At the risk of opening a whole new can of worms -- if anything, the wizards of the Harry Potter spend considerable energy developing magical approximations of Muggle technology. The wizard lifestyle is primitive by comparison to their neighbors' and you get the impression that if it weren't for the example of Muggles, they'd be living in the 5th century, not the 19th.

But I (thankfully) got away with merely auditing P-chem, so YMMV...

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20. NOBODY-CARES! on October 13, 2007 7:41 PM writes...

Y'all need to get a life.

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21. NOBODY-CARES! on October 13, 2007 7:48 PM writes...

Y'all need to get a life.
Stop bickering back and forth about what happened in the Harry Potter books and what war the Brithish won.

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22. Konfusion on October 13, 2007 8:05 PM writes...

On another note, anyone remember the Fischer-Thropp catalyst who produce syngas for fueling tanks in WWII. So again the germans took a lead in the science and put it into action for the greatness of them

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23. karavela on July 18, 2008 9:23 AM writes...

Konfusion, you can put the link of this note?

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