Lithium orthosilicate with halloysite as silicon source for high temperature CO2 capture

Abstract

Lithium orthosilicate (Li₄SiO₄)-based sorbents were synthesized using a low cost and naturally available mineral resource (halloysite) as silicon source for high temperature CO₂ capture. Halloysite nanotubes (HNTs) were acid-treated by 6 M HCl for 6 h to leach diaspore-like sheet to produce Si source (H6), which showed the best extraction effects. Pure Li₄SiO₄ (P-LS) and H6-Li₄SiO₄ (H6-LS) were thermally analyzed under a CO₂ flux. X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscopy (SEM), nitrogen adsorption, and thermogravimetric (TG) analysis were used to examine the character of the phase, morphology, and CO₂ chemisorption properties of the samples. The Li₄SiO₄ sorbent was synthesized at 800 °C for 4 h (H6-LS800), and the metal impurities especially aluminum were doped into the structure of H6-LS800, resulting in the increased surface area. Thermal analysis indicated the maximum CO₂ adsorption capacity of H6-LS800 reached up to 34.45%, with the temperature range from 350 to 720 °C, which had a better CO₂ adsorption than P-LS. In addition, H6-LS800 sorbent exhibited excellent adsorption–desorption performance.