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The Fuel

How to Generate Hydrogen from Other Kinds of Fuel

Methane as a Primary Fuel

Methane is heated at 900 °C with steam on a Ni catalyst (this operation is called 'Reforming'):

CH4 +H2O → CO + 3H2

Then CO reacts with the steam to form more H2 (this reaction is the 'Shift'):

CO +H2O → CO2 + H2

Residual CO can be removed by conversion to methane over a ruthenium catalyst, at the expense of some hydrogen, if all the CO2 is removed first:

CO + 3H2 → CH4 +H2O

Other hydrocarbons follow the same reactions as the methane, though sometimes under harder conditions.

Hydrazine (N2H4) as a Primary Fuel

Hydrazine exists as a stable liquid hydrate N2H4.H2O. It is one of the most satisfactory fuels, it is reactive enough to decompose at an electrode to form hydrogen, which enters the electrode reaction, and nitrogen, wich is released. Hydrazine is compatible with alkaline electrolytes.

N2H4 → N2 +2H2

Methanol (CH3OH) as a Primary Fuel

Methanol , made from hydrocarbons, can readily be obtained in a pure form. It will undergo direct electro-chemical oxidation at an electrode, though the CO2 produced contaminates alkaline electrolytes. In acid systems, the rate of reaction is low, but greater than of hydrocarbons. Methanol can also be reacted with steam at temperature lower than those used for hydrocarbons to form hydrogen. Both the 'reforming' and 'shift' reactions can be combined at one temperature.

CH3OH + H2O → CO2 + 3H2

CO +H2O → CO2 + H2