High selective epoxidation of 2-methylpropene over a Mo-based oxametallacycle reinforced nano composite

Compared with the gas-solid phase reactions, the epoxidation of light olefins in the liquid phase could realize the highly selective preparation of epoxides at a lower temperature. Nevertheless, the C=C bond of light olefins is more difficult to activate, and it is still a challenge to realize the dual activation of the oxidant and light olefins in one reaction system. In this contribution, an oxametallacycle reinforced nanocomposite (Mo(O₂)₂@RT) is prepared via an oxidative pretreatment strategy, and its epoxidation performance to 2-methylpropene in liquid-phase with tert-butyl hydroperoxide (TBHP) as an oxidant is evaluated. A set of advanced characterizations including field emission scanning electron microscopy, X-ray photoelectron spectroscopy, in-situ Fourier transform infrared spectroscopy (FT-IR), electron spin-resonance spectroscopy, and high-resolution mass spectrometer are implemented to confirm the physicochemical properties and the catalytic behaviors of Mo(O₂)₂@RT. This catalyst has a fast kinetic response and exhibits excellent catalytic activity in 2-methylpropene epoxidation to produce 2-methylpropylene oxide (MPO; select.: 99.7%; yield: 92%), along with good reusability and scalability. Moreover, the main epoxidation mechanism is deduced that TBHP is activated by Mo(O₂)₂@RT to generate the highly active tert-butyl peroxide radical, which realizes the epoxidation of 2-methylpropene to yield MPO.