New Hydrogen Purification Method Devised

Although President Barack Obama is seeking to raise the bar as far as renewable energy goes, there are still a few setbacks to be overcome, at least as far as hydrogen-based fuels are concerned. That is to say, in order to build H2 fuel cells for electric vehicles, or other such applications, scientists have to first purify the chemical, which takes a lot of time and money to do at the moment. Now, researchers at the Northwestern University (NU) have managed to create a new class of porous materials, capable of separating hydrogen from the most complex gas mixtures, which ensures a faster production speed and a better quality.

The new device is shaped like a honeycomb, and has the best possible effectiveness in separating H2 from carbon dioxide and methane researchers have ever seen. Chemist Mercouri G. Kanatzidis and postdoctoral research associate Gerasimos S. Armatas, both from the NU, have basically developed a totally new way of obtaining hydrogen from various mixtures, while at the same time skipping numerous side-steps that conventional chemical processes require.

“A more selective process means fewer cycles to produce pure hydrogen, increasing efficiency. Our materials could be used very effectively as membranes for gas separation. We have demonstrated their superior performance,” Kanatzidis, who is the senior author of the new research and also the Charles E. and Emma H. Morrison Professor of Chemistry at the Weinberg College of Arts and Sciences, explains.

“We are taking advantage of what we call 'soft' atoms, which form the membrane's walls. These soft-wall atoms like to interact with other soft molecules passing by, slowing them down as they pass through the membrane. Hydrogen, the smallest element, is a 'hard' molecule. It zips right through while softer molecules, like carbon dioxide and methane, take more time,” the researcher adds.

The study, published online in the February 15th issue of the journal Nature Materials, also shows that the new device has the potential to successfully separate hydrogen from a mixture composing three other gases, namely carbon monoxide, carbon dioxide, and methane. This brings hope that filters made by this new blueprint could one day be installed at smokestacks used by coal- and oil-powered electrical plants, in a bid to reuse as much energy as possible.