Butanol Production from Propylene and Syngas

The process under analysis comprises the following major sections: (1) hydroformylation; (2) butyraldehyde separation; (3) hydrogenation; and (4) Butanol purification.

Hydroformylation. Fresh propylene, syngas, recycled reactants, and recycled catalyst solution are fed to the first of two reactors operating in series. In both reactors, the propylene reacts with carbon monoxide and hydrogen at mild temperatures and low pressures, yielding n-butyraldehyde and isobutyraldehyde. The liquid effluent from the hydroformylation, containing catalyst components, reaction products, unreacted propylene, as well as aldehyde products with some dissolved gases, is depressurized and fed to a falling-film evaporator. The concentrated catalyst solution obtained from the evaporator is recycled to hydroformylation. The vapor from the evaporator is partially condensed and the uncondensed gas is recycled to the reactor through a compressor. The condensed liquid stream is sent to the butyraldehyde separation.

Butyraldehyde Separation. The condensed liquid stream from the catalyst recovery is fed to a Stabilizer, for the removal of the remaining traces of dissolved gases. The aldehyde stream is sent to the butyraldehydes splitter, where isobutyraldehyde is separated. The stream rich in n-butyraldehyde is routed to the n-butyraldehyde column, which further purifies the n-butyraldehyde from heavy impurities.

Hydrogenation. The n-butyraldehyde is charged into a hydrogenation reactor where it is reacted with hydrogen, yielding mainly n-Butanol.

Butanol Purification. The liquid stream from the hydrogenation is directed to the first of two distillation columns for the purification of n-Butanol product. In the first column, light-ends are removed and heavy impurities are removed in a second distillation column. The final product obtained is n-Butanol with 99.5 wt% purity.