Coal and natural gas are both abundant in nature and available at a very low cost compared to other resources.

  C   (Coke)  +  CH4 (Natural Gas) =  C2H4 (Ethylene)
  C2H4 + H2O   = C2H5OH (Ethanol

 Coke which represents about 80% of coal reacts with natural gas producing ethylene gas. Ethylene Hydration provides ethanol. Product ethanol outweighs other liquid fuels for its availability and low cost.  The reaction itself is obvious, a simple addition reaction where one mole of carbon reacts with one mole of methane gas producing one mole of ethylene gas.

 The reaction of coal and natural gas was used by a German manufacturer for Buna rubber: Chemische Werke Huls, at Marl, Germany, and AVCO Corp in the US. Consequently several references had described both Huls Arc Process and AVCO rotating arc reactor [1][2]. Both reactors are of cylindrical shape and have a rotating electric arc. The cathode is at the cylinder axis, while the anode is on the circumference. As methane gas provided the highest yield, then it is forced with coal powder into a vortex passing through the electric arc for few milliseconds. 

 Huls Arc Process [3] produced a mixture of acetylene and ethylene gases. The reaction conditions can be varied to determine the needed product. Increasing the Specific Energy Requirement (SER) favor acetylene production, and lower SER is for ethylene, as shown by the following enthalpy change:

 Enthalpy Change for Ethylene :[4]  = 127.34 kJ/mol, while for acetylene:  = 301.4 kJ/mol.  As a consequence, recent production processes are using conventional heating instead of electric arc.

 Hydration of ethylene gas producing ethanol is the most important process foe ethanol production. Vapor phase process is the preferred one [5] in which ethylene and steam pass over a catalyst. One of the most accepted catalyst is diatomite impregnated with phosphoric acid.

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