What is the best way to store hydrogen – this question still bothers minds of those scientists, who deal with hydrogen as one of alternative energy sources. The solution for this problem is a crucial aspect for numeous programmes, dedicated to development of new engice based on hydrogen. Scientists from Saint Petersburg have tested various substances for their ability to absorb hydrogen, including nanostructural materials, however, best result was detected for a composite material, consisting of fulleren-containing soot and magnesium hydride.

Russian researchers from science and engineering centre “Ceramic thermal machines” named after A.M. Boyko aim their work at building an experimental hydrogen storage with gas’s weight content about 60 kg and volume content not less than 5% in one cubic meter. Current traditional methods of storing nitrogen, either under high pressure in gaseous condition, or in liquid or adsorbed state, have low hydrogen parameters, both in weight and volume.

As study objects scientists have chosen various solid sorbents, based on carbon nanostructures – multi-layer nanotubes, astralenes (nanodispersible fulleroid systems) and fulleren-containing soot, which are activery studied around the world, as well as specialy treated palladium, magnesium hydride and their composites.

Researchers have performed their tests at special “hydrogen” test stand, able to work under temperatures from –180° to +800° Centigrade and pressure, varying from 0.0001 millimeter mercury column to 20 megapascals, as well as under various environmental conditions.

What main conclusion can be made on the basis of studies of Russian researchers, who explored hydrogen sorption by carbon nanostructures? Scientists found that inner cavities of said materials (central channels and interlamellar zones of nanotubes and astralenes) do not absorb hydrogen despite any type of specialized preliminary treatment for these materials. Enthusiastic researchers have tested palladium as a catalytic agent, but failed – this metal added only 1-1.5% to hydrogen absorption. Other nanomaterials – graphite fiber, activated carbon, pure fulleren dust, titanium powder and titanium metal hydride – showed much lower sorption values than powders of nanostructural materials. Fulleren-containing soot appeared to be the winner among sorbent materials – it showed best results.

Scientists have prepared powder of fulleren-containing soot, treated in with glycerol, and added magnesium hydride powder – these manipulations resulted in a sorbing agent, which hydrogen sorbing parameters fit requirements for hydrogen storages developed by the Department of Energy (DOE) of United States of America for transport power systems.

Brand new sorbent boasts following parameters – weight content of hydrogen slightly exceeds 5%, which leads to 65 kg in one cubic meter. Maximum absorption is shown under conditions of 200-350 degrees Centigrade and 1-10 megapascals. Reverse process is highly effective at temperature of 340350 degrees Centigrade.

Source:
    Russian Science News

Kizilova Anna