High temperature capture of CO₂ on lithium-based sorbents from rice husk ash
2011
Wang, Ke | Guo, Xin | Zhao, Pengfei | Wang, Fanzi | Zheng, Chuguang
Highly efficient Li₄SiO₄ (lithium orthosilicate)-based sorbents for CO₂ capture at high temperature, was developed using waste materials (rice husk ash). Two treated rice husk ash (RHA) samples (RHA1 and RHA2) were prepared and calcined at 800°C in the presence of Li₂CO₃. Pure Li₄SiO₄ and RHA-based sorbents were characterized by X-ray fluorescence, X-ray diffraction, scanning electron microscopy, nitrogen adsorption, and thermogravimetry. CO₂ sorption was tested through 15 carbonation/calcination cycles in a fixed bed reactor. The metals of RHA were doped with Li₄SiO₄ resulting to inhibited growth of the particles and increased pore volume and surface area. Thermal analyses indicated a much better CO₂ absorption in Li₄SiO₄-based sorbent prepared from RHA1 (higher metal content sample) because the activation energies for the chemisorption process and diffusion process were smaller than that of pure Li₄SiO₄. RHA1-based sorbent also maintained higher capacities during the multiple cycles.
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