Preparation of porous organic polymers containing N or P atoms and their application in hydroformylation of 1-octene

Three kinds of porous organic polymers (POPs) containing N or P atoms were prepared, named N-POP, P-POP, and N + P-POP respectively and used as the supports for Rh catalysts. Their structures and compositions were fully understood by FTIR, XRD, EDX, 13C MAS NMR, 31P MAS NMR and XPS characterizations. Rich micropores and mesopores were detected in the polymers through N2 adsorption–desorption, SEM and TEM. Because of the bulk extrusion of triphenylphosphine (TPP) unit in Rh-P-POP and Rh-N + P-POP, the Rh-N-POP showed a larger BET surface area and larger pore volume. The characterization also proved that P atoms were oxidized partly to PO species. Their catalysis performances were tested in the hydroformylation of 1-octene and syngas, with isomerization as the main competing reaction. It was interesting to see that the inactive Rh-N-POP allowed Rh to combine with free ligands more easily, thus promoting the hydroformylation activity. The existence of TPP structure in the polymers, however, greatly promoted isomerization, with a weak hydroformylation activity, partly due to the partial oxidation of P atoms. On the other hand, the strong alkalinity and coordination ability of P atoms in the polymers made the association and dissociation of Rh with other free ligands difficult.