Synthesis and characterization of lithium silicates from organosilicone precursors for carbon dioxide adsorption
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Synthesis and characterization of lithium silicates from organosilicone precursors for carbon dioxide adsorption N. Supriya1,2 · R. Rajeev1 Received: 24 January 2020 / Accepted: 30 September 2020 © Akadémiai Kiadó, Budapest, Hungary 2020
Abstract Lithium silicates are ceramic materials known for its high C O2 adsorption capacity and excellent cyclic stability at high temperatures. In the present work, an attempt has been made to use different types of organosilicone precursors viz., methyltrimethoxysilane, triethoxyphenylsilane, polyoligomericsilsesquioxane and polydimethylsiloxane as the silica precursor for the synthesis of lithium silicates for CO2 adsorption. Thermogravimetry and differential scanning calorimetry were used to optimize the thermal decomposition of precursor to lithium silicate. Polydimethylsiloxane could not produce lithium silicate, as it decomposed to form volatile cyclic silicon oligomers at high temperatures. Lithium silicates were obtained from the other three precursors and were characterized for its structure and morphological features using X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron micrography, energy-dispersive X-ray spectrometry, particle size and surface area analysers. The C O2 adsorption/desorption studies using thermogravimetry showed that lithium silicates synthesized from the silica precursor, methyltrimethoxysilane, retained a cyclic adsorption capacity of 31% for 10 cycles. The study reveals that hydrolysable aliphatic organosilicone compounds are better silica precursors for the synthesis of lithium silicates for regenerable CO2 sorption. Keywords Lithium silicate · CO2 adsorption · Organosilicones · Cyclic stability · Thermogravimetry
Introduction Considering the anomalous increase in the atmospheric concentration of carbon dioxide (CO2), techniques for its industrial and economical capture are in high demand. Burning of fossil fuels has resulted in the drastic increase in the average CO2 concentration to around 414.7 ppm as on Dec 2019 [1–3]. Flue gas from coal burning power plants constitutes about 10–15% of the C O2. Being the main source of C O2 exit to atmosphere, methods for direct CO2 capture from flue gases at high temperatures are preferred considering the high energy penalty and cost in cooling the flue gas [4–6]. Among the various separation technologies like absorption, adsorption, cryogenic separation, membrane separation and micro-algal bio-fixation adopted for carbon capture and * R. Rajeev [email protected]; [email protected] 1
Analytical and Spectroscopy Division, Vikram Sarabhai Space Centre, Thiruvananthapuram, Kerala 695022, India
Department of Applied Chemistry, Cochin University of Science and Technology, Kochi, Kerala 682022, India
2
storage, adsorption technique is considered as a competitive solution, considering its ease of regeneration by thermal or pressure modulation [7–9]. The adsorbents available for CO2 separation are alkaline ceramics, zeolites, activated carbons, porous carb
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