Exploring the Catalytic Potential of ZIF-90: Solventless and Co-Catalyst-Free Synthesis of Propylene Carbonate from Propylene Oxide and CO2.

Reported is the application of ZIF-90, which is a highly porous zeolitic imidazolate framework, as a novel catalyst for the cycloaddition of propylene oxide (PO) with CO2 in the absence of co-catalysts and solvents under moderate reaction conditions. The effects of various reaction parameters were investigated. The activity of ZIF-90 was compared with that of various metal-organic-framework (MOF)-based catalysts for the cycloaddition of PO with CO2 . Density functional theory calculations elucidated the role of ZIF-90 in creating a favorable environment for the PO-CO2 cycloaddition reaction. A reaction mechanism for the ZIF-90-catalyzed PO-CO2 cycloaddition on the basis of DFT calculations is proposed and the regeneration of ZIF-90 is discussed.