Hydrogen car for the future

The green fuel car of the future could be a step closer thanks to the development of materials which store and release hydrogen efficiently.

The research is reported in the latest edition of the Royal Society of Chemistry's Journal of Materials Chemistry.

If hydrogen is to have a realistic prospect as a car fuel, materials are needed which can not only take in and store large volumes of hydrogen, but - crucially - can release it again when required.

Dr Gemma Turnes Palomino and a team at the University of the Balearic Islands, Palma de Mallorca, have modified materials called zeolites by incorporating magnesium into them.

Zeolites are porous minerals that can be made synthetically, but are also found naturally in volcanic rock.

Using magnesium strengthens the interaction between the hydrogen and the zeolite, known as the adsorption enthalpy.

If the adsorption enthalpy is too low, stored gas is released too easily, while if too high the hydrogen will not be released at all. The ideal value for the adsorption enthalpy is minus 15 kilojoules per mole.

Zeolites developed in the past have had adsorption enthalpies of between minus 5 and minus 10 kilojoules per mole.

The magnesium containing zeolite, however, has a value of minus 17.5 kilojoules per mole - much closer to ideal.

Dr Peter Nachtigall, a zeolite expert from the Academy of Sciences of the Czech Republic, Prague, said: "This contribution certainly brings very interesting and new findings and it will trigger new interest in metal-exchanged zeolites for hydrogen storage."

with thanks to Paul O'Sullivan for the original article