Catalytic hydrogenation of olefins and their mixtures using HRh(CO)(TPPMS)3 complex in an aqueous biphasic medium

The synthesis and characterization of the catalyst precursor HRh(CO)(TPPMS)3 was carried out by ligand exchange techniques starting from HRh(CO)(PPh3)3 with an excess of TPPMS ligand [TPPMS] = (C6H5)2P(m-C6H4SO3Na), or prepared in situ from RhCl3·3H2O and TPPMS under high purity syngas. When the hydrosoluble complex was used as a catalyst precursor in the two phase hydrogenation reaction of 1-hexene, cyclohexene, styrene and 2,3-dimethyl-1-butene, the main hydrogenated products were obtained with high conversion rates. Under the following reaction conditions T = 343 K, P = 13.6 atm, 600 rpm and S/C = 600/1, the substrates showed the following reactivity order: styrene > 1-hexene > cyclohexene > 2,3-dimethyl-1-butene. A quaternary equimolar mixture and one quaternary mixture which simulates the olefin quantities present in real naphtha, showed the same hydrogenation order. The catalyst showed recycling properties without significant loss of activity and sulfur tolerance when benzothiophene is present in the olefin mixtures.

The synthesis and characterization of the water-soluble complex HRh(CO)(TPPMS)3 is described. This complex was obtained in situ and by ligand exchange procedures. These analyses confirmed that the rhodium complex has a trigonal prismatic arrangement. The complex was used as a catalytic precursor for the aqueous biphasic hydrogenation of several olefins and olefins mixtures. The observed catalytic activity was styrene > 1-hexene > cyclohexene > 2,3-dimethyl-1-butene. The catalyst was shown to be resistant to sulfur poisons.Figure optionsDownload as PowerPoint slide