Doped Lithium Orthosilicate for Absorption of CO2 At Steam Atmosphere with Low CO2 Partial Pressure

Calcium and lithium containing oxides are regarded as options for the capture of CO₂ in sorption-enhanced steam methane reforming (SESMR) system. Among the latter, lithium orthosilicate (Li₄SiO₄) is considered as one of the most potential materials due to its large capacity, high selectivity and good cycle performance. Improved properties can be obtained by appropriately doping different elements into Li₄SiO₄. In this study, the best amount of doping elements (K, Fe) into Li₄SiO₄ were calculated by Factsage 5.5. Therefore, different lithium orthosilicate based absorbents, potassium doped and iron doped lithium orthosilicate according to the calculated results from Factsage 5.5 were prepared and characterized by XRD, SEM. For the study of practical applicability in SESMR, the absorption ability was investigated by TGA under low CO₂ partial pressure (5%~20%) influenced by different steam atmosphere (5%~30%). In addition, the cyclic absorption/desorption performance of different absorbents were also investigated. The results show that potassium and iron can enhance the absorption capacity at low CO₂ partial pressure and cyclic ability respectively and the best absorbent with suitable amount of potassium and iron was obtained.