Effect Of Different Silicon Sources On The High Temperature CO₂ Sorbent Capture Performance Of Li₄SiO₄

Li4SiO4 is considered as one of the most promising CO2 sorbents due to its high sorption capacity and rate.Although,lithium containing ceramics have marvelous CO2 sorption performances at high temperatures,many limitations still exist.High production cost and poor regeneration performance represent sorbent constrain in practical applications.Moreover,as one of the raw materials,SiO2 will directly influence on the cost,morphology and CO2 capture performance of Li4SiO4.In this paper,the characterization and CO2 sorption performance of Li4SiO4 which were synthesized from natural material(vermiculite)and artificial material(zeolite and vermiculite/zeolite hybrid)were disclosed.The intercorrelation between characterization of silicon source and CO2 sorption capacity performance of Li4SiO4 was exploded.Consequently,a series of new Li4SiO4 sorbents were synthesized by solid-state method.The morphology,specific surface area and components of sorbents were characterized by XRD,BET,XRF and SEM.Meanwhile,the CO2 sorption performance of Li4SiO4 were texted by TGA,including the sorption capacity at different sorption condition and cycling stability performance.The result reveals that sorption performance was greatly affected by the content of Li4SiO4 in sorbent and porosity of sorbent particles.Furthermore,sorbent with high purity of Li4SiO4 usually exhibits excellent CO2 capture performance in pure CO2 atmosphere.Such as Li4SiO4 sorbents which were synthesized from acid treated vermiculite and zeolite,the CO2 sorption capacity reached 34.4 wt%and 34.9 wt%,respectively.However,these two Li4SiO4 sorbents were strongly affected by the sorption temperature and CO2 concentration due to the dense and non-porous agglomerated particles.Notwithstanding,due to the separating effect by the existing impurity phases in vermiculite,Li4SiO4 sorbent which was synthesized from raw vermiculite possesses better dispersion of Li4SiO4 nanoparticles and higher porosity,which resulted in excellent cycling stability.Likewise,vermiculite-Li4SiO4 exhibited much excellent CO2 sorption capacity and faster sorption rate in low CO2 concentration atmosphere.But,the impurity phases limited the CO2 sorption capacity of such sorbent in higher temperature.Based on this result,synthesized hierarchical Li4SiO4 nanoparticles/flakers composite from vermiculite/MCM-41 hybrid has high content Li4SiO4 phase and rich pores.Furthermore,the result demonstrate that these hybrid-type sorbents possession improved CO2 capture performance under different CO2.These hybrid-type Li4SiO4 sorbents less affected by the concentration of CO2 and sorption temperature.Additonally,(vermiculite/MCM-41)-Li4SiO4 also exhibits excellent regeneration performance,so it has better industrial application prospect.