Energy from acids

Scientists develop a catalyst for converting cheap acids into hydrogen

Published: Saturday 15 December 2001

hydrogen powered vehicles are amongst the most promising clean vehicles that are on the design board. Unlike engines powered by conventional hydrocarbons like petrol, hydrogen burns leaving only water as a waste. No carbon dioxide or carbon monoxide is released. But the easy and cheap availability of hydrogen is a major concern in widespread use of these environment friendly engines. Now a team of chemists in the us has developed a catalyst that could convert cheap acids into hydrogen.

T Rauchfuss and colleagues at the University of Illinois at Urbana-Champaign have tried to mimic certain hydrogen-producing bacteria to produce the catalyst. There are certain kinds of bacteria for whom hydrogen production is a part of their metabolism. Hydrogen is produced in metabolic reactions in which carbon dioxide and nitrogen are converted into useful compounds. It is believed that during the early period of life on our planet, the atmosphere had a higher concentration of carbon dioxide and nitrogen and the bacteria developed metabolic adaptations to take advantage of this. These bacteria have enzymes called hydrogenases that use acids to make hydrogen gas.

There are two kinds of hydrogenases: in one, the enzyme has a nickel and an iron atom while in the other there are two iron atoms. The iron atoms are attached to other chemical groups and a protein coat protects the entire core.

The synthetic catalyst developed by the chemist mimics the core and could be produced easily and cheaply. With the use of this catalyst, it is possible to convert cheap acids into hydrogen thereby solving the problem of the availability of hydrogen for hydrogen powered fuel cells used in most prototypes of zero emission vehicles.

At the moment, the usual way to make hydrogen is by electrolysing seawater, something that requires a lot of energy and thus adds to the problem of pollution indirectly. The researchers are now developing a version of the catalyst, which could dissolve in water making its industrial production easier and cheaper (Journal of the American Chemical Society , Vol 123, p9476).

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