Design of bifunctional NH3I-Zn/SBA-15 single-component heterogeneous catalyst for chemical fixation of carbon dioxide to cyclic carbonates

Abstract

The novel bifunctional Zn/SBA-15 supported ammonium salt (NH3I-Zn/SBA-15) as single-component heterogeneous catalyst for the coupling of CO2 with epoxides was developed. FT-IR, XRD, N2 adsorption/desorption, TEM, XPS techniques were used to determine the morphological structure and physicochemical properties of NH3I-Zn/SBA-15 sample. The catalyst exhibited exceptionally effective activity with 93% yield and 99% selectivity and a high TOF of 306h−1 to propylene carbonate at 130°C and 3MPa of CO2 for 12h in the absence of cocatalyst and solvent participation. Also the catalytic system was versatile to the cycloadditions of other epoxides with CO2 under the optimized reaction conditions. Additionally, the catalyst was easily recycled and reused only with slight loss of activity after five recycles. Besides, a possible catalytic mechanism involving cooperative activation of epoxide and ring-opening by one-component and bifunctional catalyst was proposed. The protocol herein provides important insights on design of novel single-component heterogeneous catalysts for CO2 relevant transformations.