Featured Research

from universities, journals, and other organizations

Chemists Offer New Hydrogen Purification Method

Date:
February 25, 2009
Source:
Northwestern University
Summary:
One of the hydrogen economy's roadblocks to success is the hydrogen itself. Hydrogen needs to be purified before it can be used as fuel for fuel cells, but current methods are not very clean or efficient. Researchers have developed a class of new porous materials, structured like honeycomb, that is very effective at separating hydrogen from complex gas mixtures. The materials exhibit the best selectivity in separating hydrogen from carbon dioxide and methane.

Hydrogen (white) passes quickly through the pores of a new material developed at Northwestern while carbon dioxide (red and black) interacts with the walls, slowing it down. The material offers a new method for gas separation.
Credit: Image courtesy of Northwestern University

President Barack Obama's pursuit of energy independence promises to accelerate research and development for alternative energy sources -- solar, wind and geothermal power, biofuels, hydrogen and biomass, to name a few.

For the hydrogen economy, one of the roadblocks to success is the hydrogen itself. Hydrogen needs to be purified before it can be used as fuel for fuel cells, but current methods are not very clean or efficient.

Northwestern University chemist Mercouri G. Kanatzidis, together with postdoctoral research associate Gerasimos S. Armatas, has developed a class of new porous materials, structured like honeycomb, that is very effective at separating hydrogen from complex gas mixtures. The materials exhibit the best selectivity in separating hydrogen from carbon dioxide and methane, to the best of the researchers' knowledge.

The results, which offer a new way to separate gases not available before, will be published online Feb. 15 by the journal Nature Materials. The materials are a new family of germanium-rich chalcogenides.

"A more selective process means fewer cycles to produce pure hydrogen, increasing efficiency," said Kanatzidis, Charles E. and Emma H. Morrison Professor of Chemistry in the Weinberg College of Arts and Sciences and the paper's senior 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.

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 methods, which are made of lighter elements, such as silicon, oxygen and carbon.

"We are taking advantage of what we call 'soft' atoms, which form the membrane's walls," said Kanatzidis. "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."

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.

Another advantage is that the process takes place at what Kanatzidis calls a "convenient temperature range" -- between zero degrees Celsius and room temperature.

Small-molecule diffusion through porous materials is a nanoscopic phenomenon, say the researchers. All the pores in the hexagonal honeycomb structure are ordered and parallel, with each hole approximately two to three nanometers wide. The gas molecules are all at least half a nanometer wide.


Story Source:

The above story is based on materials provided by Northwestern University. Note: Materials may be edited for content and length.


Journal Reference:

  1. Armatas et al. Mesoporous germanium-rich chalcogenido frameworks with highly polarizable surfaces andrelevance to gas separation. Nature Materials, 2009; DOI: 10.1038/nmat2381

Cite This Page:

Northwestern University. "Chemists Offer New Hydrogen Purification Method." ScienceDaily. ScienceDaily, 25 February 2009. <www.sciencedaily.com/releases/2009/02/090215151755.htm>.
Northwestern University. (2009, February 25). Chemists Offer New Hydrogen Purification Method. ScienceDaily. Retrieved July 22, 2014 from www.sciencedaily.com/releases/2009/02/090215151755.htm
Northwestern University. "Chemists Offer New Hydrogen Purification Method." ScienceDaily. www.sciencedaily.com/releases/2009/02/090215151755.htm (accessed July 22, 2014).

Share This




More Matter & Energy News

Tuesday, July 22, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Government Approves East Coast Oil Exploration

Government Approves East Coast Oil Exploration

AP (July 18, 2014) The Obama administration approved the use of sonic cannons to discover deposits under the ocean floor by shooting sound waves 100 times louder than a jet engine through waters shared by endangered whales and turtles. (July 18) Video provided by AP
Powered by NewsLook.com
Sunken German U-Boat Clearly Visible For First Time

Sunken German U-Boat Clearly Visible For First Time

Newsy (July 18, 2014) The wreckage of the German submarine U-166 has become clearly visible for the first time since it was discovered in 2001. Video provided by Newsy
Powered by NewsLook.com
Obama: U.S. Must Have "smartest Airports, Best Power Grid"

Obama: U.S. Must Have "smartest Airports, Best Power Grid"

Reuters - US Online Video (July 17, 2014) President Barak Obama stopped by at a lunch counter in Delaware before making remarks about boosting the nation's infrastructure. Mana Rabiee reports. Video provided by Reuters
Powered by NewsLook.com
Crude Oil Prices Bounce Back After Falling Below $100 a Barrel

Crude Oil Prices Bounce Back After Falling Below $100 a Barrel

TheStreet (July 16, 2014) Oil Futures are bouncing back after tumbling below $100 a barrel for the first time since May yesterday. Jeff Grossman is the president of BRG Brokerage and trades at the NYMEX. Grossman tells TheStreet the Middle East is always a concern for oil traders. Oil prices were pushed down in recent weeks on Libya increasing its production. Supply disruptions in Iraq fading also contributed to prices falling. News from China's economic front showing a growth for the second quarter also calmed fears on its slowdown. Jeff Grossman talks to TheStreet's Susannah Lee on this and more on the Energy Department's Energy Information Administration (EIA) report. Video provided by TheStreet
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins