Olefins Hydroformylation On PPh₃ Modified Heterogeneous Catalyst In A Fixed-bed Reactor

Homogeneous catalysts display high activity and selectivity under mild conditions in a variety of reactions as they provide easy access to the catalytic sites, however, many homogeneous catalytic systems can not be commercialized because of the complicated and expensive catalyst separation from products, while heterogeneous catalysts reduce separation problems, but their activity is usually lower due to the limited access to the catalytic sites. As a result, combination of the advantages of homogeneous and heterogeneous catalysts has been an interesting topic for many years.The dissertation has studied a series of PPh3 modified heterogeneous catalysts, which combine the advantages of homogeneous and heterogeneous catalysis. The catalysts display high activity and selectivity under mild conditions, and free of metal leaching in a fixed-bed reactor of ethylene, propylene and FCC off-gas hydroformylation. The results give scientific proof and technical parameters for the practical applications of the catalyst.TEM, XPS, solid-state 31P MAS NMR, in situ FT-IR, TG and CO-TPD were employed to characterize the PPh3-Rh/SiO2 and PPh3-Rh/SBA-15 catalysts for the structure, bonding, oxidation state, and the interaction between Rh and triphenyl phosphine. The characteristics of homogeneous catalyst and heterogeneous catalyst are compatible on the system of PPh3 modified heterogeneous catalysts at the reaction atmosphere. All the characterizations and experiments confirm that the reason for high activity and high regioselectivity is that homogeneous active species in situ grow on the surface of heterogeneous catalyst, and the problem of metal leaching is greatly reduced by directly fastening Rh particles on the support; and the active Rh species that was responsible for the outstanding performance of...