Extraction of rhodium from supported liquid-phase hydroformylation catalysts with supercritical carbon dioxide

The continuous extraction of the rhodium inventory in supported liquid-phase (SLP) catalytic materials utilized in the hydroformylation (HyFo) of 1-butene was investigated by supercritical carbon dioxide (scCO 2 ). Optimization of extraction efficiency involved varying parameters such as temperature (90 and 120 °C), pressure (10, 20 and 30 MPa), and the addition of methanol as a polar co-feed to the extraction medium (0–20 vol%). The results underscored the critical role of methanol in facilitating extraction, as experiments employing pure scCO 2 yielded no rhodium recovery. Furthermore, extraction performance demonstrated sensitivity to temperature and pressure adjustments during the process. Notably, the use of 10 vol% methanol at 120 °C and 30 MPa achieved complete rhodium extraction from the grained SLP materials, which was identified as the optimum extraction condition. This study highlights the potential for scaling up in-situ rhodium extraction processes within HyFo production plants based on SLP catalysts, emphasizing significant implications for industrial applications. • Quantitative Rh extraction shown from hydroformylation SLP catalysts with scCO 2. • Extraction efficiency of scCO 2 affected by temperature, pressure and co-feed. • Study shows potential for Rh extraction in hydroformylation production plants.