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The Swedish Academy of Sciences, in awarding this
year’s Nobel Prize for chemistry to Gerhard Ertl, a professor at
the Max Planck Institute in Germany, cited his work on “chemical
reactions [that] take place on surfaces.”
Surface chemistry is
another name for catalysis, the chemical reaction that underpins
much of modern industry and, if enzymes were included, life itself.
The Academy put
special emphasis on an improved chemical process to extract nitrogen
from the air, with iron as the catalyst, for artificial fertilizers.
It’s a process of “enormous economic significance.”
The idea of
catalysis—a chemical reaction by a substance (the catalyst) that’s
not itself destroyed in the reaction—is as old as alchemy whose
principal object was the transmutation of a base metal like lead
into gold. But fundamental understanding of catalysis that could
lead to “catalysis by design” remains elusive. George M.
Whitesides, a professor of chemistry and chemical biology at
Harvard, wrote in the Feb. 9 issue of Science: “Given the enormous
importance of catalysis in the production and storage of energy, in
the production of petrochemicals and the materials derived from
them, and in all biological and most geochemical processes, it is
astonishing [and a little disheartening] how little is known of the
fundamentals of catalysis: how catalysts operate, how to control
them, and especially how to generate new ones.”
Among the uses at
present of catalysis are in cracking petroleum into fuels and other
derivatives; in biological reactions involved in photosynthesis; in
the hydration of CO2 into carbonate ion; in the movement of
electrons in batteries; in the operation of fuel cells; in cleaning
up toxic car emissions of which the catalytic converter is the first
successful device.
The process that the
Nobel committee singled out, the Haber-Bosch process, has been known
since the Second World War—nitrogen reacts with hydrogen on an
iron surface to make ammonia, an ingredient for the manufacture of
explosives and fertilizers—that allowed Germany to keep on
fighting for at least four years. What Ertl contributed is a more
efficient process resulting from an understanding of the basic
mechanisms of the chemical reactions of gases and iron at the
molecular level.
Before Ertl,
catalysis, according to Mark Peplow, the editor of Chemistry World,
was a hit-or-miss affair: “Throw some metal and gas together to
see what happens. Ertl allowed us to do this strategically.”
One of them, sheer
magic even to professional chemists, was doing controlled
experiments inside a vacuum by making a single layer of molecules
rest on the surface of a catalyst.
As far as I know,
the only other Nobel laureate who worked in catalysis was Irving
Langmuir, an American chemical physicist who studied in Göttingen
with Walther Nernst, a pioneer in chemical thermodynamics and the
discoverer of the third law of thermodynamics. Langmuir gained
notoriety, before he got his Nobel in 1932, for his fraught
relationship with Gilbert Lewis over the so-called octet group in
chemical bonding—but that’s another story.
It was Langmuir’s
ideas on surface adsorption that advanced understanding of
heterogeneous catalysis.
He was also by the
way the first Nobel Prize winner to come from industry; in his case,
General Electric Co. where he worked for 41 years. Among his
contributions to the profitability of GE was the argon-filled
tungsten filament lamp and a welding torch that used a recombination
of atomic hydrogen (H2) to achieve muzzle heat of 6,000°C.
Leading edge
research into biofuels involves the use of microbes and enzymes to
unlock the structural sugars in plants and to convert them into
ethanol.
But a chemical
engineer at the University of Wisconsin in Madison, James Dumesic,
is taking another tack. He’s exploring catalysis as the process to
transform sugars and carbohydrates into hydrogen (H), liquid fuels,
and materials for plastics.
In 2002, Dumesic and
his team used platinum to catalyze the production of hydrogen gas
from a solution of carbohydrates in water (Science, February 9,
2007). They call it aqueous phase reforming (APR), a low-temperature
process that uses less energy than steam reforming in which water
vapor interacts with methane (CH4). From these experiments a
practical biorefinery that’s energy efficient may one day become
possible.
Ertl’s “contribution
was doing very detailed experiments to understand how [catalysis]
happens,” Bruce Bursten, the president-elect of the American
Chemical Society, said.
By honoring Gerhard
Ertl, the Swedish Academy of Sciences has called the attention of
the world to the role that chemistry can play in mitigating climate
change.
When world leaders
convene in Bali, Indonesia, in December this year, I hope that they
will agree to work together on an urgent program that will make
catalysis by design feasible before the middle of the century.
Gerhard Ertl has shown the way.
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