Butanol can be produced by chemical synthesis. One process is Oxo-synthesis, which in­volves the reaction of propylene with carbon monoxide and hydrogen in the presence of co­balt or rhodium as the catalyst. The mixture of n-butyraldehyde and isobutyraldehyde are obtained and then the mixture can be hydrogenated to the corresponding n-butanol and iso­butyl alcohols (Park, 1996).The reactions are as following:

CH3CH2CH2CHO + H2 ® CH3CH2CH2CH2OH (a)

(CH3 )2 CHCHO+H2 ® (CH3 )2 CHCH2OH (b) (2)

When using cobalt as the catalyst, the reaction processes at 10~20MPa and 130~160°°C, the products ratio of n-butyraldehyde and isobutyraldehyde is 3. Rhodium as the catalyst used in industry from 1976 and the reaction processes at 0.7-3MPa and 80-120°°C. The products ratio of n-butyraldehyde and isobutyraldehyde can reach 8-16. Hydrogenaration processes by using the catalyst of nickel or copper in gaseous phase or nickel in liquid phase. Some by­products can be transferred into butanol at high temperature and high pressure that will en­hance the product purity.

Another route is aldol condensation, which involves the reaction of condensation and dehy­dration from two molecules of acetic aldehyde. And then, the product crotonaldehyde was transformed into n-butanol by hydrogenation at 180°°C and 0.2MPa. The reaction is as fol­lowing: ch3ch=chcho+2h2—> ch3ch2ch2ch2oh

Comparing the two processes, Oxo-synthesis route has the advantages of materials easily obtained, comparable moderate reaction conditions, enhanced ratio of n-butanol to isobutyl alcohol. So, Oxo-synthesis process is the main industrial route for n-butanol production. There are also some other fossil oil derived raw materials such as ethylene, propylene and triethylaluminium or carbon monoxide and hydrogen are used in butanol production (Zver- lov, et al., 2006).