Soft Atoms Enhance Hydrogen Purification
The technology choice for purifying hydrogen won’t be hard, hope researchers at Northwestern University, Evanston, Ill. They have developed porous materials that use “soft” atoms to provide high selectivity in separating hydrogen from gas mixtures. The honeycomb-like structures rely on polarization instead of pore size for their effectiveness — and thus provide a new separation method, they say. “Soft atoms are large atoms with large electronic clouds around them which can be affected (sloshed around easily) by the application of electric fields. These are like large rubber balloons,” explains Mercouri Kanatzidis, professor of chemistry at the school. “We achieve high polarizability by using large heavy atoms (e.g., lead, germanium and tellurium).” “Most known porous materials are oxides. Oxides are hard,” he adds.
Figure 1 -- Better separation: Hydrogen (white) passes quickly
through the pore while carbon dioxide (red and black) interacts
with the walls.
Source: Northwestern University.
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