2-Propylheptanol Production from Butenes and Syngas

The process under analysis comprises 3 major sections: (1) Hydroformylation; (2) Aldolization; and (3) Hydrogenation.

Hydroformylation. Syngas and raffinate-2 are purified in order to protect biophosphite-modified rhodium catalyst. A stirred-tank receives the raw material feed and a catalyst solution. The butylenes react with carbon monoxide and hydrogen at mild temperatures and low pressures, yielding valeraldehyde. The crude reaction product is fed to a degasser, where dissolved lights vaporize. The vapor stream is mixed with reactor vent gases and is recycled to the reactor after pressurization. The liquid is heated in a vaporizer and then fed to a flash vessel, where a concentrated catalyst solution is separated from a vapor phase containing hydroformylation products and remaining reactants.

Aldolization. The vapor stream form flash vessel is freed from residual butenes and butanes, that are sold as fuel. The resulting valeraldehyde-rich liquid is fed to a stirred tank along with a caustic soda solution catalyst. An aldolization reaction occurs, yielding 2-Propyl-2-heptenal and water. The effluent is sent to a reactive column, which strippes off light ends and unreacted valeraldehyde from reactor effluent. In a decanter, the liquid stream is separated into caustic soda solution and 2-Propyl-2-heptenal.

Hydrogenation. The 2-Propyl-2-heptenal solution is distilled from heavy ends, that are separated from the 2-Propyl-2-heptenal stream in column bottom. The overhead outlet is condensed and is submitted to a liquid-phase hydrogenation in two steps, carried out over heterogeneous catalysts, yielding 2-Propylheptanol. The products are then submitted to a fractional distillation, in which pure 2-Propylheptanol is separated from light-ends and other impurities.