CO2 cycloaddition to epichlorohydrin over an aluminum fumarate metal-organic framework synthesized by a sonochemical route

Aluminum fumarate was tested as a catalyst for CO2 cycloaddition to epichlorohydrin under solvent-free reaction conditions. This material was synthesized hydrothermally via a sonochemical route (Al fumarate-(S)), which exhibited a higher catalytic activity than Al fumarate synthesized by a conventional method owing to the higher number of Lewis acid sites formed in Al fumarate-(S). The CO2 uptake of Al fumarate-(S) was high: approximately 269 mg g−1 at 25 °C and 10 bar. High conversion (96%) of epichlorohydrin with excellent selectivity (97%) to cyclic carbonate was obtained at 50 °C and 10 bar CO2 after 6 h of reaction. The kinetic analysis of the reaction confirmed an approximately 1st order dependence on the epichlorohydrin concentration and CO2 pressure with an activation energy of approximately 39 kJ mol−1. The recovered Al fumarate-(S) catalyst, however, showed a steady decline in catalytic activity during the recycling runs, as reported for other metal-organic framework catalysts. The deactivation was monitored by N2 adsorption-desorption isotherms and spectroscopic analyses.