Synthesis and characterization of lithium silicates from organosilicone precursors for carbon dioxide adsorption

Lithium silicates are ceramic materials known for its high CO 2 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 CO 2 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 CO 2 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 CO 2 sorption.