Fe-substituted Polyoxometalate-based Spherical Assemblies as Catalysts for Olefin Epoxidation

Fe-substituted polyoxometalate(Na 15 [(P 2 W 15 O 56 ) 2 Fe 3 ])(Fe-POM)-based composite (C 19 H 42 N) 15 [(P 2 W 15 O 56 ) 2 Fe 3 ](CTAB-Fe-POM) was successfully synthesized through an ion-exchanged method. Then, it was self-assembly in a mixed solvent to form surfactant encapsulated complex nanosphere(SECN). The as-prepared SECN was employed as the catalyst for the epoxidation of olefins with H 2 O 2 . Compared with (C 19 H 42 N) 6 [α-P 2 W 18 O 62 ](CTAB-P 2 W 18 ), SECN shows a higher activity in the epoxidation of cis -cyclooctene with a high yield(97.3%). The extraordinary performance could be attributed to the amphiphilic module of cetyltrimethylammonium bromide(CTAB), which improves the dispersion of the catalyst in CH 3 CN and accelerates the catalytic reaction. And Fe atom can rapidly activate H 2 O 2 , forming the active intermediate Fe-OOH to realize the transfer of active “O”. Furthermore, the catalyst could be reused five times without significant loss of activity.