Amines immobilized double-walled silica nanotubes for CO2 capture.

Novel silica support has been required for high amine loading and good CO2 molecule diffusion into its pores to increase the performance of CO2 adsorbents. Herein, amine groups supported on double-walled silica nanotubes (DWSNTs) have been prepared via the immobilization of various aminosilanes (primary, secondary, tertiary, di-, and tri-aminosilanes) on DWSNT, and found to be a very effective adsorbent for CO2 capture. Amine groups immobilized DWSNTs captured CO2 reversibly in a temperature swing process at various adsorption temperatures (25°C, 50°C, 75°C, and 100°C). The amines on modified DWSNTs showed high CO2 capture capacity in the order of tri-, di-, primary, secondary, and tertiary amines. The CO2 capture capacity of all aminosilanes immobilized DWSNTs decreased linearly with the increase of the adsorption temperature. We expect that DWSNT would be able to inspire researchers to use it not only as a support for CO2 capture but also as a promising candidate for various applications.