Abstract:The concept of supported ionic liquid phase (SILP) catalysis has been extended to 1-butene hydroformylation. A rhodium-sulfoxantphos complex was dissolved in [BMIM][n-C 8 H 17 OSO 3 ] and this solution was highly dispersed on silica. Continuous gas-phase experiments in a fixed-bed reactor revealed these SILP catalysts to be highly active, selective and long-term stable. Kinetic data have been acquired by variation of temperature, pressure, syngas composition, substrate and catalyst concentration. A linear dependency in rhodium concentration could be established over a large concentration range giving another excellent hint for truly homogeneous catalysis in the SILP system. Compared to former studies using propene, the SILP system showed significantly higher activity and selectivity with 1-butene as feedstock. These findings could be elucidated by solubility measurements using a magnetic microbalance.