Scientists report improved hydrogen purification technologies

Two groups of scientists are reporting the results from research into purifying hydrogen for use in fuel cells.  Northwestern University chemist Mercouri G. Kanatzidis and postdoctoral research associate Gerasimos S. Armatas, now with the University of Crete, have developed a class of new porous materials, structured like honeycomb, that they say is very effective at separating hydrogen from complex gas mixtures. The materials could be used to purify hydrogen.  The materials are a new family of germanium-rich chalcogenides and exhibit the best selectivity in separating hydrogen from carbon dioxide and methane, according to the researchers. Their results will be published online Feb. 15 by the journal Nature Materials.

Kanatzidis and Armatas say that their new materials rely on polarisation for separation -- the interaction of the gas molecules with the walls of the material as the molecules move through the membrane.

Kanatzidis and Armatas tested their membrane on a complex mixture of four gases. Hydrogen passed through first, followed in order by carbon monoxide, methane and carbon dioxide. As the smallest and hardest molecule, hydrogen interacted the least with the membrane, and carbon dioxide, as the softest molecule of the four, interacted the most.

The process takes place at what Kanatzidis calls a "convenient temperature range" -- between zero degrees Celsius and room temperature.

A team of researchers from Virginia Tech, Oak Ridge National Laboratory, and the University of Georgia says it has produced hydrogen gas pure enough to power a fuel cell by mixing 14 enzymes, one coenzyme, cellulosic materials from nonfood sources, and water heated to about 90 degrees Fahrenheit (32 C).

The group announced three advances from their one pot process: a novel combination of enzymes, an increased hydrogen generation rate, and a chemical energy output greater than the chemical energy stored in sugars.

The researchers used cellulosic materials isolated from wood chips, but crop waste or switchgrass could also be used.  These research results are being published in the ChemSusChem.

Sources: http://www.sciencedaily.com/releases/2009/02/090215151755.htm
http://www.thaindian.com/newsportal/health/scientists-cook-up-enzyme-cocktail-to-produce-pure-hydrogen-gas_100154180.html

Source: Fuel Cell Today