Phosphorus-31 NMR spin lattice relaxation times as an indirect probe of adsorbed water in supported aqueous phase catalysts

Abstract

Phosphorus-31 spin lattice relaxation times, T₁'s, for SAP hydroformylation catalysts derived from HRh (CO) (TPPTS)₃ and TPPTS (TPPTS = trisulfonated triphenyl phosphine trisodium salt) are consistent with a liquid-like character for the supported aqueous phase. Ale T₁ for solid TPPTS is 1150 s while for TPPTS in a supported aqueous phase T₁ varies from 220 to 4.9 s. A T₁ of 4.9 s is close to the value obtained for TPPTS in solution and is observed at a H₂O/P ratio of 24.9. At this level of water content previously reported SAP catalysts have shown maximum catalytic activity for the hydroformylation of olefins.