Ethylene is widely used in chemical industry, and its worldwide production(over 109 million tonnes in 2006) exceeds that of any other organic compound. Commercially ethylene is obtained by(1)thermal cracking of hydrocarbons such as ethane, propane, butane, naphtha, kerosene, gasoil, crude oil, etc, (2) auto thermic cracking (partial oxidation) of the above hydrocarbons, (3)recovery from refinery off-gas, (4) recovery from coke-oven gas, and(5) catalytic dehydration of ethyl alcohol or ethyl ether. The thermal cracking process is the most interesting process to produce ethylene commercially...