PEP Review 90-3-4
Low Pressure Oxo Process with Liquid Recycle
Published: January 1992
In the 1970s, Union Carbide, Davy McKee, and Johnson Matthey jointly developed a process to produce mixed butyraldehydes by the hydroformylation of propylene with synthesis gas in the presence of an oil-soluble rhodium/phosphine catalyst. The rhodium catalyst allowed the reaction to occur at lower temperatures and pressures and resulted In higher ratios of n-butyraldehyde to isobutyraldehyde than the previously used cobalt carbonyl catalyst.
A preliminary process flow diagram and estimated production costs were presented in PEP Report 21C, Oxo Alcohols, for a low pressure oxo process that makes use of an oil-soluble rhodium complex. This review presents an updated version of the Union Carbide/ Davy McKee/Johnson Matthey low pressure oxo process. Rather than stripping the product from the reaction mixture with a recycle gas stream, leaving the catalyst and heavier products in the reactor, the reaction product is removed from the reactor in the liquid phase. The rhodium catalyst is separated from the reaction products and is recycled to the reactor.