Thaindian News

Washington, Feb 17 (IANS) Hydrogen needs to be purified before it can be used as fuel, but existing methods are not very clean or efficient and this comes in the way of their success.

Northwestern University chemist Mercouri G. Kanatzidis, together with postdoctoral research associate Gerasimos S. Armatas, have developed a class of new porous materials, structured like honeycomb, that effectively separate hydrogen from complex gas mixtures.

The materials, a new family of germanium-rich chalcogenides, exhibit the best selectivity in separating hydrogen from carbon dioxide and methane.

“A more selective process means fewer cycles to produce pure hydrogen, increasing efficiency,” said Kanatzidis, professor at the Weinberg College of Arts and Sciences and the paper’s co-author.

“Our materials could be used very effectively as membranes for gas separation. We have demonstrated their superior performance.”

Current methods of producing hydrogen first yield hydrogen combined with carbon dioxide or hydrogen combined with carbon dioxide and methane.

The technology currently used for the next step — removing the hydrogen from such mixtures — separates the gas molecules based on their size, which is difficult to do.

Kanatzidis and Armatas offer a better solution. Their new materials do not rely on size for separation but instead on polarization — the interaction of the gas molecules with the walls of the material as the molecules move through the membrane. This is the basis of the new separation method, said a Northwestern release.

Tests of one form of the family of materials — this one composed of the heavy elements germanium, lead and tellurium — showed it to be approximately four times more selective at separating hydrogen from carbon dioxide than conventional materials, which are made of lighter elements, such as silicon, oxygen and carbon.

The results were published online by Nature Materials.