Confinement effect of rhodium(I) complex species on mesoporous MCM-41 and SBA-15: Effect of pore size on the hydroformylation of 1-octene

Rhodium(I) complexes based on triphenylphosphine (TPP) and water soluble trisodium salt of triphenylphosphine (TPPTS) as catalysts precursors were successfully anchored on mesoporous silica (MCM-41 and SBA-15) to study the effect of confinement by an inorganic support in catalysis. The performance of the immobilized complexes was investigated in the hydroformylation of 1-octene and compared with the catalytic results of homogeneous catalysts. High activities and regioselectivies towards n-nonanal were obtained for the immobilized catalysts. Overall, heterogenized catalysts offered regioselectivity towards n-nonanal in the range of 80-90% compared to their homogeneous counterparts (70-96%) in the hydroformylation of alkenes based on TPP. We found that the pore size had a remarkable effect on the in situ formation of Rh-phosphine carbonyl complexes. Furthermore, adding excess of TPP and TPPTS ligand enhances the catalytic performance of the catalyst system during hydroformylation of 1-octene. The catalysts could be reused several times without loss of activity or selectivity under identical reaction conditions.