B2O3: A heterogeneous metal-free Lewis acid catalyst for carbon dioxide fixation into cyclic carbonates

Abstract

Boron trioxide (B2O3), a common and easily available boron oxide, was first reported as an effective metal-free heterogeneous catalyst for the chemical fixation of CO2 with epoxides to produce cyclic organic carbonates (COCs). The ball-milling treatment of B2O3 significantly enhanced the catalytic activity by increasing the adsorption capacity to propylene oxide substrate. In situ DRIFTS characterization indicated there was a ring opening process of epoxides on the surface of B2O3, which was induced by the boron sites from B2O3. The recovery test of B2O3 showed that it could be easily recycled and reused for 5 runs without a loss of activity. This kind of Lewis acid catalytic property of B2O3 marks a rare case of a metal-free heterogeneous catalyst mimicking the metal-based catalysts for the COCs production.