A continuous hydroformylation process in a miniplant scale: equipment design for the separation of three liquid phases

Abstract

Abstract A novel process concept for the hydroformylation of long chain olefins in micro emulsions is investigated and developed within the framework of a Collaborative Research Centre in Germany. In this process, the liquid feed material (C12 olefin) is brought in contact with a hydrophilic rhodium-ligand-complex, which is dissolved in an aqueous phase while forming a micro emulsion system under the use of non-ionic surfactants. The hydroformylation reaction is started by adding syngas (H 2 &CO) into a continuously stirred tank reactor (CSTR). Due to phase separation into an aqueous phase (catalyst-rich) and an organic phase (product-rich), the valuable rhodium catalyst can be retrieved and recycled. This key separation step is challenging and crucial for the technical and economic feasibility of the overall process concept and plant design. Depending on the temperature the mixture decomposes into two or even three liquid phases. Preliminary investigations have shown that product and catalyst separation in a continuous process is only attainable in the three phase state, given the required separation time and quality. However, due to the lack of thermodynamic data for micro emulsion mixtures, the design of the phase separation unit strongly depends on experimental data. Consequently, a systematic experimental approach has been developed to identify potential operating conditions and relevant design parameters. In order to classify and find these, a set of systematic experimental set-ups have been investigated to characterize impact factors on the phase separation such as type of surfactant, different concentrations of surfactant, olefin, product, and water. With the information gained through the observations the relevant composition of the investigated mixture and the separation temperature are determined for the operating conditions. Finally, necessities with regards to plant and process design are revealed.