2-Ethylhexanol Production from Propylene and Syngas

The process under analysis comprises three major sections: (1) Propylene Hydroformilation; (2) EPA Formation; and (3) EPA Hydrogenation.

Propylene Hydroformilation. Fresh propylene and syngas are treated to remove impurities that could poison the rhodium catalyst employed in the hydroformylation reaction, which yields n-butyraldehyde (NBAL) and iso-butyraldehyde (IBAL) as products. The reactor outlet is degassed, and unreacted gaseous reactants return to the reactor through a Vent Gas Compressor, while a liquid stream is routed to Catalyst Removal area. A flash vessel separates a liquid stream, sent to two absorber columns operating alternatively for catalyst regeneration, from a gas stream that is sent to a C3 Stripper. This stripper recovers propylene, which is sent to C3 Absorber and then returns to hydroformilation, while an aldehyde stream is routed to a distillation column to separate the NBAL from the IBAL.

EPA Formation. The NBAL is fed to the Condensation Reactor along with a caustic soda solution. where 2-ethyl-3-propyl acrolein (EPA) is formed. The product mixture is sent to the Reactive Column to strip off unreacted NBAL, which is returned to the reactor. The bottom stream from the Reactive Column is sent to a decanter to separate an organic phase of EPA from an aqueous phase of caustic soda, which is returned to the Condensation Reactor.

EPA Hydrogenation. The EPA solution from the decanter is fed to a distillation column, where heavy impurities are separated and removed from the EPA stream, which is condensed and routed to two hydrogenation zones, in which it reacts with hydrogen in the presence of heterogeneous catalysts, yielding 2-ethylhexanol. The product stream is sent to a column to purify the 2-EH, removing light ends as purge gas and discharging an aqueous phase as wastewater, and obtaining 2-EH from its bottom.