Heterogeneous reactive extraction for an intensified alcohol production process

The heterogeneously catalysed hydration of olefins with ion exchange resins in randomly packed trickle bed and flooded bed reactors is a widely used process for the production of sec. alcohols, e.g. isopropyl alcohol (IPA). Typically, such processes are operated at temperatures ranging from 130 °C to 190 °C and pressures between 6 MPa and 10 MPa. Therefore, alcohol and water are in liquid state and the olefin is in liquid or supercritical state, respectively. The alcohol is formed in the water swollen gel phase of the macroporous ion exchanger and may be extracted by means of an olefin rich organic phase which is immiscible with the aqueous phase surrounding the catalyst beads. In presently operated industrial processes the importance of this simultaneous extraction is not fully considered. By the continuous removal of alcohol from the catalyst phase the driving forces for the reaction can be maintained on a high level and the selectivity for alcohol production can be improved. This work proposes a new reactor concept where the reactor is equipped with a structured catalytic packing for enhanced mass transfer performance. The new reactor then operates as a heterogeneous reactive extraction column offering similar advantages like reactive distillation processes. Furthermore, the modified reactor concept leads to a less energy demanding product purification sequence significantly lowering the operative costs for the process. As a result, the analysis of processes as a whole can be a promising approach to process intensification especially when modifications to one process unit affect other units.