Improved CO₂ adsorption capacity and CO₂/CH₄ and CO₂/N₂ selectivity in novel hollow silica particles by modification with multi-walled carbon nanotubes containing amine groups

چکیده مقاله

Accumulation of greenhouse gases (GHGs) in the atmosphere is responsible for enhanced global warming of our planet. In the present study, hollow silica spherical particles (HSSP) and multi-walled carbon nanotubes containing amine groups composite (denoted NH₂-CNT@HSSP) were synthesized as adsorbents in a single-step and used to investigate the adsorption capacity and selectivity of CO₂, CH₄ and N₂. The crystal structures and morphology of HSSP modified with different amounts of NH₂-CNTs were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), thermogravimetric analysis (TGA) and N₂ adsorption/desorption isotherms. The CO₂ adsorption capacity of the NH₂-CNTs/HSSP is better than HSSP. CO₂ adsorption capacity for HSSP is about 7.71 mmol g⁻¹ when HSSP were composited with the amine-modified carbon nanotubes, CO₂ adsorption capacity is increased (from 7.71 to 13.80 mmol g⁻¹) at 298 K and 20 bar. CO₂ capture on the adsorption sites by amine loading is believed to occur via chemisorption mechanism by formation of ammonium carbamate. The optimum adsorbent showed its stability with the adsorption capacity remaining constant over three adsorption/desorption cycles. © 2019