Optimization of Li4SiO4 synthesis conditions by a solid state method for maximum CO2 capture at high temperature

The aim of this research work is to optimize the synthesis of Li 4 SiO 4 by a solid state method to maximize CO 2 capture. This includes evaluating the main characteristics of the synthesised material which enhance the CO 2 uptake performance. Starting from Li 2 CO 3 and SiO 2 pure reagents, the eff...

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Veröffentlicht in:Journal of materials chemistry. A, Materials for energy and sustainability Materials for energy and sustainability, 2018, Vol.6 (7), p.3249-3257
Hauptverfasser: Izquierdo, M. T, Turan, A, García, S, Maroto-Valer, M. M
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Sprache:eng
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Zusammenfassung:The aim of this research work is to optimize the synthesis of Li 4 SiO 4 by a solid state method to maximize CO 2 capture. This includes evaluating the main characteristics of the synthesised material which enhance the CO 2 uptake performance. Starting from Li 2 CO 3 and SiO 2 pure reagents, the effect of the sintering process conditions (heating rate, synthesis temperature and holding time) of the previously mixed powders has been studied. The samples were characterized by N 2 physisorption, particle size distribution and X-ray diffraction. The evaluation of the CO 2 uptake performance of the samples has been carried out at 600 °C using a thermobalance under a flow of almost pure CO 2 . Unreacted Li 2 CO 3 is present at low synthesis temperatures, and its content in the synthesised material decreases when higher temperatures are used, so complete conversion to Li 4 SiO 4 is reached at 900 °C. At this temperature, the maximum CO 2 uptake was found to be 20%, although it was yet far from the stoichiometric CO 2 uptake value of 36.7%. The holding time at a synthesis temperature of 900 °C was then varied and a maximum CO 2 uptake of 30.5% was obtained for a holding time of 2 h. Finally, under the optimised synthesis temperature and holding time conditions, the heating rate was varied. A value of 5 °C min −1 was found as the optimum one as the use of either lower or higher heating rates has a negative effect on the CO 2 uptake performance. As crystalline phases, the particle size and BET surface area were very similar among all the prepared samples at 900 °C; the crystal size was identified as the main physical property that could explain the CO 2 uptake performance of the samples, i.e. , the lower the crystal size, the higher the CO 2 uptake. Optimum Li 4 SiO 4 synthesis conditions have been obtained by a SS method to enhance CO 2 uptake: the lower the crystal size the higher the uptake.
ISSN:2050-7488
2050-7496
DOI:10.1039/c7ta08738a