Amine-modified silica nanotubes and nanospheres: synthesis and CO2 sorption properties

Abstract

Silica nanotubes (SNT) and silica nanospheres (SNS) were prepared in the presence of Pluronic F127 triblock copolymer. Post-synthesis grafting and co-condensation were used to introduce aminopropyl groups on the surface of SNT and SNS, respectively. Nitrogen adsorption was employed to evaluate the surface area and porosity of unmodified and modified SNT and SNS. These materials were tested for CO₂ capture at ambient (25 °C) and elevated (120 °C) temperatures and showed high sorption uptakes (0.91–2.87 mmol g⁻¹) at 120 °C. The CO₂ uptakes obtained at 1.2 atm and 25 °C for SNT, SNS, and aminopropyl-modified SNT and SNS are 2.81, 2.06, 2.35, and 1.54 mmol g⁻¹, respectively. The microporosity of the samples was shown to be beneficial for CO₂ physisorption under ambient conditions, while basic amine groups were essential for enhancing CO₂ chemisorption at elevated temperatures.