Aluminum, when placed in water, reacts with the release of hydrogen. But that’s in theory. In practice, aluminum is coated with a rhinestone oxide film, which protects the metal from corrosion and makes it inactive when interacting with water. Scientists at the Massachusetts Institute of Technology found outhow best to activate aluminum for simple and controlled extraction of hydrogen from scrap and waste.
Researchers immediately rejected the idea of specifically producing aluminum for storage, transportation and further production of hydrogen and energy based on it. Although aluminum can “store” hydrogen with a 10-kr excess of density compared to compressed gas, the production of this metal is extremely energy-intensive. Scrap and waste of aluminum is another matter. Instead of recycling, they can be used to generate hydrogen and produce “green” energy. It does not require energy consumption. The reaction only needs water and the technology to remove the oxide layer from aluminum. And such a technology, which also does not require energy costs, was developed and tested at MIT.
It should be said that the surface of aluminum products has a granular and porous structure. Therefore, the oxide film must be removed from a very difficult surface with depressions. It turned out that this is best done by precisely calibrated compounds of the metals gallium and indium, which remain in a liquid state at room temperature. Within 48–96 hours, gallium and indium compounds independently and completely penetrated into the relief of the aluminum surface and removed the oxide film, after which aluminum easily reacted with water and began to release hydrogen. In the future, gallium and indium can be removed from the solution and reused.
Scientists also found out that the rate and duration of hydrogen release from aluminum scrap is influenced by impurities that are added to the metal to obtain the desired properties – strength, fusibility, corrosion resistance, or others. It can be silicon, magnesium, or something else. Depending on the impurity, the reaction of aluminum with water with the release of hydrogen can proceed with different intensities and different rates. This provides a process control mechanism, although the aluminum scrap will have to be pre-sorted to do this.
The researchers note that they have shown the possibility of controlled production of hydrogen from aluminum scrap by presenting options for taking into account impurities and pretreating raw materials. Business should then enter the game if it finds this area interesting.