2-Ethylhexanol Production Process
The 2-Ethylhexanol (2-EH) produce from propylene and syngas. The process under analysis comprises three major sections:
(1) Propylene Hydroformilation;
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.
(2) EPA Formation
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.
(3) EPA Hydrogenation
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.
Figure 1. 2-Ethylhexanol (2-EH) Production Process
2-Ethylhexanol
2-Ethylhexanol is an eight-carbon branched chain oxo alcohol having a high boiling point and slow evaporation rate. It is a versatile solvent featuring excellent reactivity as a chemical intermediate. It serves as a chain terminator in synthesizing condensation polymers and as an intermediate for plasticizers. 2-Ethylhexanol has low volatility and enhances the flow and gloss of baking enamels. It is also used as dispersing agent for pigment pastes.
2-Ethylhexanol ranks, after the lighter alcohols (methanol to butanol), as the most important synthetic alcohol. It is an eight-carbon branched chain alcohol and appears as a clear, colorless liquid, with a characteristic odor. It is an organic solvent miscible in almost all organic solvents and practically insoluble in water and one of the most important oxo alcohols commercialized. 2-Ethylhexanol is a very flammable liquid (flash point at 77°C), so it should be transported and stored away from heat, sparks, flame, or other sources of ignition. It should also be kept in tightly closed containers, away from strong oxidants, acids or bases, in an area without drain or sewer access, preferably with ventilation along the floor. Like other alcohols, 2-Ethylhexanol does not attack standard metals, and can be transported in iron drums, tank trucks, or railway cars made of standard steel, aluminum, or stainless steel. 2-Ethylhexanol is the most widely used of the synthetically made higher aliphatic alcohols. This alcohol is miscible with most common organic solvents, and enters into the reactions that are typical for primary alcohols, such as esters formation with various acids.