The Fischer-Tropsch process

used by SASOL

In 1923, Fischer and Tropsch developed a method of producing synthetic hydrocarbons.
Water gas is produced by passing steam over whitehot coke.

C(s) + H2O(g) ® CO(g) + H2(g) D H = +127 kJ

Further hydrogen is added to the gas mixture which is passed over a hot thorium(IV) oxide catalyst at high pressure.

nCO(g) + (2n + 1)H2(g) ® CnH2n+2(g) + nH2O(g)

This process was one fuel source for Germany in WW2.
A modification is used by SASOL (South Africa).

Excuse me, what is the meaning of that last equation?
The equation means that there are many simultaneous reactions, so many different hydrocarbons are produced;

CO(g) + 3H2(g) ® CH4(g) + H2O(g)

4CO(g) + 9H2(g) ® C4H10(g) + 4H2O(g)

16CO(g) + 33H2(g) ® C16H34(g) + 16H2O(g)

The Fischer-Tropsch process has been slightly modified for natural gas.
Reformed gas (syn gas) is produced by the controlled burning of natural gas.

2CH4(g) + O2(g) ® 2CO(g) + 4H2(g)

The carbon monoxide/hydrogen proportion is corrected.
Carbon monoxide and hydrogen are reacted to produce liquid hydrocarbons. This process is being put into operation by countries with excess natural gas, as shipping petroleum is less costly then shipping L.N.G.

What's the heat of reaction for that methane oxidation?

C(s) + 2H2(g) ® CH4(g) D H = -74.9 kJ mol-1

C(s) + 2O2(g) ® CO(g) D H = -115 kJ mol-1

so:

2CH4(g) ® 2C(s) + 4H2(g) D H = -149.8 kJ

2C(s) + O2(g) ® 2CO(g) D H = -230 kJ

finally

2CH4(g) + O2(g) ® 2CO(g) + 4H2(g) D H = -80.2 kJ