Isononanol Production from Octenes (Cobalt Catalyst)

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

Hydroformylation. The Hydroformylation is comprised of a series of four water cooled reactors. The first reactor receives mixed octenes with absorbed cobalt catalyst from an absorber column, as well as pressurized synthesis gas. The effluent of one reactor is cooled down in heat exchangers before being routed to the subsequent reactor, which is also fed with synthesis gas. The octenes react with the carbon monoxide and hydrogen contained in the synthesis gas to form the corresponding aldehydes with chain length of 9 carbons.

Hydrogenation. The crude product flows to an intermediate vessel, where pressure is reduced and the hydrogen and carbon monoxide dissolved in the liquid phase are released. The liquid reaction product is routed to the top of a Stripper column, where part of the catalyst is recovered. At low pressures the catalyst is unstable, so the other part passes through a regeneration system before it is recycled to absorber. The organic phase from the stripper is still washed with acidic water to remove traces of cobalt. The cobalt-free stream is mixed with pressurized hydrogen and fed to a fixed-bed reactor, where the aldehydes are catalytically hydrogenated in the presence of a trimetalic catalyst to form the isononyl alcohols with high selectivity.

Purification. The crude alcohol stream formed is sent to three columns for purification. Light and heavy ends are used as fuel, and aldehydes are recycled to hydrogenation. Finally, the alcohol stream is still passed through a hydrorefining step in the presence of hydrogen and a nickel based catalyst. This step serves to remove trace levels of unsaturation, as well as convert any remaining aldehyde into the corresponding alcohol.