Q.Write a note on Fischer tropsch synthesis.

Fischer-Tropsch synthesis catalytically converts a mixture of carbon monoxide and hydrogen (syngas/water gas) into liquid hydrocarbons over a cobalt/iron catalyst, producing synthetic petrol.

The Fischer-Tropsch process starts from synthesis gas ('syngas' or water gas), a mixture of carbon monoxide and hydrogen typically obtained by passing steam over red-hot coke: $C + H_2O \rightarrow CO + H_2$. This gas mixture is then passed, at moderate temperature (about 470-500 K) and pressure, over a finely divided cobalt or iron catalyst (often promoted with thoria, $ThO_2$), where CO and $H_2$ combine to build up hydrocarbon chains: $nCO + (2n+1)H_2 \xrightarrow[\text{Co/Fe catalyst}]{\Delta,\ p} C_nH_{2n+2} + nH_2O$ The product is a mixture of saturated and unsaturated hydrocarbons of varying chain lengths, which is fractionated to give a synthetic petroleum-like fuel ('synthetic petrol'). This process was historically important for producing motor fuel from c …