Abstract
Using diatomite and analytical pure SiO2 as silicon sources, Li4SiO4 sorbents for high temperature CO2 capture were prepared through solid-state reaction method. Phase composition was analyzed by X-ray diffraction, and the CO2 absorption capacity and absorptoin-desorption performance were studied by the simultaneous thermal thermogravimetric analyzer (TG-DSC). The results showed that silicon source had an important influence on CO2 absorption properties. The kinetic parameters for the chemisorption and diffusion processes were obtained by the isothermal study for different silicon sources. The results showed that the activation energies for these two processes were estimated to be 105.427 and 35.928 kJ/mol for the sample with analytical pure SiO2 (AS). While for the sample with diatomite (DS), the activation energies for these two processes were estimated to be 78.500 and 20.439 kJ/mol, respectively.
Highlights
Using diatomite and analytical pure SiO2 as silicon sources, Li4SiO4 sorbents for high temperature CO2 capture were prepared through solid-state reaction method
Compared with the lithium-based sorbents prepared by Marin et al [14], the resultant Li4SiO4 sorbents have the higher CO2 absorption capacity and better cyclic properties
Novel Li4SiO4 sorbents from diatomite for high temperature CO2 capture were prepared at low preparation cost
Summary
Diatomite (75%SiO2, C.R., Shanghai Fengxian Reagent Co. Ltd., China) and SiO2 (99%, A.R., Traditional China Medicine Chemical Reagent Co. Ltd., China) were used as silicon sources. Li2CO3 (97%, A.R., Tianjin Fengchuan Chemical Reagent Co. Ltd., China) was used as the starting powders. Li4SiO4 materials were synthesized according to reaction (1) at 700°C for 2 h. Crystalline phases were identified by XRD (D8ADVANCE, Germany) analysis. The absorption properties of Li4SiO4 materials with different silicon sources were investigated into the gas mixture (50 mL/min N2 and 50 mL/min CO2) by TG-DSC (STA 449 F3, Netch Co. Ltd., Germany). As seen from reaction (2), the theoretical absorption capacity of Li4SiO4 is 36.7 wt%
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