The influence of triphenylphosphine trisulfonate (TPPTS) ligands on the catalytic activity of the supported ionic liquid-phase catalysts for the hydroformylation of ethylene

Triphenylphosphine trisulfonate (TPPTS) is a common used ligand for homogeneous hydroformylation of olefins with Rh complexes. The synthesis of the TPPTS ligand is a rather complex procedure and it is influenced by several factors. In this work, the influence of pH on the synthesis of the TPPTS ligand was thoroughly studied and a neutralization pH of 5.5-6.5 was optimized for a successful synthesis of TPPTS-Cs-3 and TPPTS-Na-3 ligands. The catalytic activity of the corresponding Rh-TPPTS supported ionic liquid-phase (SILP) catalysts with SiO2 and TiO2 supports were studied for the continuous, fixed-bed gas-phase hydroformylation of ethylene to propanal. The SILP catalyst with TPPTS-Cs-3 on SiO2 support exhibited superior catalytic activity compared to a corresponding catalyst with TPPTS-Na-3, while the activity of the latter catalyst was found to be much higher than an analogous catalyst based on TiO2 support. Combined this clearly emphasizing the importance of both ligand and support characteristics in the SILP hydroformylation system.