Scientists finely control methane combustion to get different products

April 14, 2011
This diagram shows how catalysts of two gold atoms can help convert methane into ethylene at room temperature (shown in red) and into formaldehyde at lower temperatures (shown in blue). Credit: Uzi Landman

Scientists have discovered a method to control the gas-phase selective catalytic combustion of methane, so finely that if done at room temperature the reaction produces ethylene, while at lower temperatures it yields formaldehyde. The process involves using gold dimer cations as catalysts — that is, positively charged diatomic gold clusters. Being able to catalyze these reactions, at or below room temperature, may lead to significant cost savings in the synthesis of plastics, synthetic fuels and other materials. The research was conducted by scientists at the Georgia Institute of Technology and the University of Ulm. It appears in the April 14, 2011, edition of The Journal of Physical Chemistry C.

"The beauty of this process is that it allows us to selectively control the products of this catalytic system, so that if one wishes to create , and potentially methyl alcohol, one burns by tuning its with oxygen to run at lower temperatures, but if it's ethylene one is after, the reaction can be tuned to run at ," said Uzi Landman, Regents' and Institute Professor of Physics and director of the Center for Computational Materials Science at Georgia Tech.

Reporting last year in the journal Angewandte Chemie International Edition, a team that included theorists Landman and Robert Barnett from Georgia Tech and experimentalists Thorsten Bernhardt and Sandra Lang from the University of Ulm, found that by using gold dimer cations as catalysts, they can convert methane into ethylene at room temperature.

This time around, the team has discovered that, by using the same gas-phase gold dimer cation , methane partially combusts to produce formaldehyde at temperatures below 250 Kelvin or -9 degrees Fahrenheit. What's more, in both the room temperature reaction-producing ethylene, and the formaldehyde generation colder reaction, the gold dimer catalyst is freed at the end of the reaction, thus enabling the catalytic cycle to repeat again and again.

The temperature-tuned catalyzed methane partial combustion process involves activating the methane carbon-to-hydrogen bond to react with molecular oxygen. In the first step of the reaction process, methane and oxygen molecules coadsorb on the gold dimer cation at low temperature. Subsequently, water is released and the remaining oxygen atom binds with the methane molecule to form formaldehyde. If done at higher temperatures, the oxygen molecule comes off the gold catalyst, and the adsorbed methane molecules combine to form through the elimination of hydrogen molecules.

In both the current work, as well as in the earlier one, Bernhardt's team at Ulm conducted experiments using a radio-frequency trap, which allows temperature-controlled measurement of the reaction products under conditions that simulate realistic catalytic reactor environment. Landman's team at Georgia Tech performed first-principles quantum mechanical simulations, which predicted the mechanisms of the catalyzed reactions and allowed a consistent interpretation of the experimental observations.

In future work, the two research groups plan to explore the use of multi-functional alloy cluster catalysts in low temperature-controlled catalytic generation of synthetic fuels and selective partial combustion reactions.

Explore further: Chemists reinvent the science and industry of making plastics

Related Stories

Chemists reinvent the science and industry of making plastics

October 12, 2006

Chemists at the University of Pennsylvania have created a new process for free radical polymerization, the chemical reaction responsible for creating an enormous array of everyday plastic products, from Styrofoam cups to ...

Oxidation mechanisms at gold nanoclusters unraveled

October 8, 2010

Researchers believe that the puzzle of catalytic gold is now partially solved. Gold can catalyse an oxidation reaction by first oxidising itself. New research evidence on gold-oxide phase at room temperature and atmospheric ...

Greenhouse gas chemistry

November 30, 2010

If fossil fuels burn completely, the end products are carbon dioxide and water. Today the carbon dioxide is a waste product, one that goes into the air -- adding to global warming; or the oceans -- acidifying them; or underground ...

Accounting for scale in catalysis

March 14, 2011

( -- Depicting a catalyst's behavior in the real world just got a lot easier, thanks to scientists in the Institute for Interfacial Catalysis (IIC) at Pacific Northwest National Laboratory. They used complex calculations ...

Recommended for you

The universe's most miraculous molecule

October 9, 2015

It's the second most abundant substance in the universe. It dissolves more materials than any other solvent. It stores incredible amounts of energy. Life as we know it would not be possible without it. And although it covers ...

New method facilitates research on fuel cell catalysts

October 8, 2015

While the cleaning of car exhausts is among the best known applications of catalytic processes, it is only the tip of the iceberg. Practically the entire chemical industry relies on catalytic reactions. Therefore, catalyst ...

Trio wins Nobel Prize for mapping how cells fix DNA damage

October 7, 2015

Tomas Lindahl was eating his breakfast in England on Wednesday when the call came—ostensibly, from the Royal Swedish Academy of Sciences. It occurred to him that this might be a hoax, but then the caller started speaking ...

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

not rated yet Apr 14, 2011
whoa , this sounds big. as if you could simulate combustion along a whole spectrum of temperature gradients, and possible along pressure gradients as well? and find out that you get a whole array of products. interesting research.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.