Efficient molybdenum(vi) modified Zr-MOF catalysts for epoxidation of olefins

Abstract

Efficient molybdenum(VI) modified Zr-MOF catalysts have been successfully prepared for the epoxidation of olefins. The stable and porous Zr-MOF (UiO-66(NH₂)) was modified with salicylaldehyde, pyridine-2-aldehyde, or 2-pyridine chloride by the post-synthesis modification (PSM) method, and then the Mo-based catalyst was loaded by a chelating method. The MOFs not only act as the carriers of the Mo(VI) catalyst, but also improve the contacting ability between the substrate and the active center of the Mo(VI) compound. The high dispersion of the Mo catalyst on Zr-MOF and the big pore size of MOF guarantee sufficient contact between substrate and catalytic active center, thus accelerating the rate of reaction and providing improved catalytic efficiency for the epoxidation of olefins. The obtained Zr-MOF catalyst exhibited high activity for the epoxidation of olefins with 70 wt% tert-butyl hydroperoxide (TBHP) or 30% H₂O₂ as the oxygen sources. Furthermore, MoO₂(acac)₂ loaded Zr-MOF was prepared in the same way, and it also showed good catalytic performance for the epoxidation of olefins.