Hydrocarbon synthesis

Hydrocarbon Synthesis is the generation of hydrocarbon molecules from other molecules containing hydrogen and carbon. On Mars production will start with In situ resources utilization of the air (with CO2), and local water.

Methods

Natural Synthesis

Some bacteria and algae naturally produce hydrocarbons such as methane. Bioengineered microbes could be used in an industrial scale. All living organisms use hydrocarbons for energy storage and the elaboration of living tissues. Biomass is the portion of hydrocarbons in a plant that cannot be used as food.

Algae, bacteria and plants also produce complex hydrocarbons in the form of oils and fats for energy storage, or as lignite and cellulose for structure.

Artificial Synthesis

The building blocks of hydrocarbons, Hydrogen and Carbon, are readily available on Mars. Carbon Dioxide is the major component of the atmosphere. Water from the surface of Mars can be split through electrolysis. These building blocks can be assembled through various chemical reactions.

Sabatier Reaction

Production of methane is possible via the Sabatier reaction:

CO₂ + 4H₂   ↔   CH₄ + 2H₂O

The forward reaction takes place in the presence of high temperatures and pressures, with a catalyst. Catalysts of nickel, ruthenium, or alumina can be used.

Reverse Water-Gas Shift Reaction

Carbon monoxide can be produced via the Reverse Water-Gas Shift Reaction:

CO₂ + H₂ → CO + H₂O (deltaH = +9 kcal/mole)

The catalyst for this reaction is silica with 5% copper and a small amount of nickel.

Fischer-Tropsch Reaction

The Fischer-Tropsch reaction converts hydrogen and carbon monoxide into various hydrocarbons.

(2n+1)H₂ + nCO → C_nH_(2n+2) + nH₂O

'n' is any positive number.

Catalysts for this reaction include iron, cobalt, ruthenium, and nickel.

The reaction can produce C₂H₄ Ethylene, than serves as a precursor for polyethylene.