Sabatier reaction

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The Sabatier reaction or Sabatier process involves the reaction of hydrogen with carbon dioxide at elevated temperatures and pressures in the presence of a nickel catalyst to produce methane and water. Optionally ruthenium on alumina makes a more efficient catalyst. It is described by the following reaction:

CO₂ + 4H₂ → CH₄ + 2H₂O

It was discovered by the French chemist Paul Sabatier. It has been proposed as a key step in reducing the cost of manned exploration of Mars (Mars Direct) through In-Situ Resource Utilization. After producing water by combining hydrogen transported from Earth and carbon dioxide taken from the atmosphere of Mars, oxygen would be extracted from the water by electrolysis and used as a rocket propellant. The stoichiometric propulsion fuel mix ratio is 1:8 hydrogen:oxygen by weight (each lb of hydrogen requires 8 lb of oxygen to burn), and if only the light hydrogen has to be transported, and the heavy oxygen extracted locally, that would result in a very considerable weight savings which would have to be transported to Mars.