Metal-free amino-incorporated organosilica nanotubes for cooperative catalysis in the cycloaddition of CO2 to epoxides

Abstract

The novel amino-incorporated benzene-bridging organosilica nanotubes (AM-NT) were used to efficiently catalyze the cycloaddition of CO2 to epoxides, producing cyclic carbonates under mild conditions. The highest activity was achieved on AM0.4-NT nanotubes with a pore diameter of ∼7 nm and a length of ∼60 nm in presence of tetrabutylammonium iodide (TBAI). The remarkably enhanced catalytic performance could be ascribed to the cooperative effect of the silanols as acid sites and the amino groups as basic sites, facilely generated in the channel, as well as the transport of substrates and products facilitated by the nanotubes with large pore diameters and short lengths as well as hydrophobicity. Moreover, the catalyst exhibited effective catalytic activity for a broad range of epoxides with a reasonable reusability.