Cleaner Ethylene Production Technique Prevents Climate Emissions

The technology created by scientists at the U.S. Department of Energy’s Argonne National Laboratory is a high-temperature membrane that can produce ethylene from an ethane stream by removing pure hydrogen.

"This is a clean, energy-efficient way of producing a chemical that before required methods that were expensive and wasteful and also emitted a great deal of pollution," said inventor ceramics scientist Balu Balachandran.

Because the new membrane lets only hydrogen pass through it, the ethane stream does not come into contact with atmospheric oxygen and nitrogen, preventing the creation of a miasma of greenhouse gases - nitrogen oxide, carbon dioxide and carbon monoxide - associated with the traditional production of ethylene by pyrolysis, in which ethane is exposed to jets of hot steam.

"By using this membrane, we essentially enable the reaction to feed itself," Balachandran said. "The heat is produced where it is needed."

The new membrane reactor performs an additional chemical trick by constantly removing hydrogen from the stream.

In this way, the membrane enables the reaction to make more ethylene that it theoretically could have before reaching equilibrium.

"We are essentially confusing or cheating the thermodynamic limit," Balachandran said. "The membrane reactor thinks: 'hey, I haven't reached equilibrium yet, let me take this reaction forward.'"

H hopes to extend the project by pairing with an industrial partner who would produce the membranes commercially.

Ethylene has many uses in all aspects of industry. Farmers and horticulturalists use it as a plant hormone to promote flowering and ripening, especially in bananas.

Doctors and surgeons have also long used ethylene as an anesthetic, while ethylene-based polymers can be found in everything from freezer bags to fiberglass.

The world’s ethylene producers manufacture more than 75 million metric tons of ethylene per year, releasing millions of tons of greenhouse gases.

The results of the research will be presented at the 2008 Clean Technology conference in Boston in June. The work was funded by the Department of Energy's Industrial Technology Program.

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