The breakthrough suggests a better way of producing the hydrogen that propels rockets and energizes battery-like fuel cells. In a few decades, it could even help the world meet key energy needs — without carbon emissions contributing to the greenhouse effect and climate change.
The researchers took a microscopic high-pressure cooker called a diamond anvil cell (within a tiny space about as wide as a pencil lead), in which they combined ingredients: aluminum oxide, water, and the mineral olivine. Set at 200 to 300 degrees Celsius and 2 kilobars pressure — comparable to conditions found at twice the depth of the deepest ocean. They cooked it for 24 hours.
Isabelle Daniel of University Claude Bernard Lyon explained that scientists have long known nature's way of producing hydrogen. When water meets the ubiquitous mineral olivine under pressure, the rock reacts with oxygen (O) atoms from the H2O, transforming olivine into another mineral, serpentine — characterized by a scaly, green-brown surface appearance like snake skin.
The process also leaves hydrogen (H2) molecules divorced from their marriage with oxygen atoms in water.
The novelty in the discovery is how aluminum profoundly accelerates and impacts the process.
Finding the reaction completed in the diamond-enclosed micro space overnight, instead of over months as expected, left the scientists amazed. The experiments produced H2 some 7 to 50 times faster than the natural "serpentinization" of olivine.
Over decades, many teams looking to achieve this same quick hydrogen result focused mainly on the role of iron within the olivine, Dr. Muriel Andreani said. Introducing aluminum into the hot, high-pressure mix produced the eureka moment.
Jesse Ausubel, of The Rockefeller University and a founder of the DCO program, said current methods for commercial hydrogen production for fuel cells or to power rockets "usually involve the conversion of methane (CH4), a process that produces the greenhouse gas carbon dioxide (CO2) as a byproduct. Alternatively, we can split water molecules at temperatures of 850 degrees Celsius or more — and thus need lots of energy and extra careful engineering.
Daniel said they believe the serpentinization process may be underway on many planetary bodies- notably Mars. The reaction may take one day or one million years but it will occur whenever and wherever there is some water present to react with olivine- one of the most abundant minerals in the solar system.
The study was published in the journal American Mineralogist.
--ANI (Posted on 09-12-2013)