CaO/SiC(O) nanocomposites for CO2 capture at higher temperatures: Synthesis, characterization, and initial performance studies

Abstract

This study presents the synthesis and characterization of CaO/SiC(O) nanocomposites via chemical modification of allylhydridopolycarbosilane (SMP) using two calcium precursors: calcium acetylacetonate (CaAcac) and calcium hydroxide (CaOH). ATR-FTIR analysis showed that CaAcac chemically interacts with SMP, promoting hydrosilylation and extensive cross-linking, while CaOH showed no interaction. Thermogravimetric analysis revealed higher than expected ceramic yields for CaAcac-modified SMP samples, whereas CaOH-modified SMP samples matched theoretical values. XRD and TEM results showed that CaAcac leads to mostly amorphous ceramics, while CaOH facilitated CaO crystallization at 600 °C. The nanocomposites captured 2–5 wt% CO₂ at 500 °C, which is comparable to the uptake of pure CaO derived from CaCO₃ due to their low CaO content (11–15 %). However, only the amorphous CaAcac modified nanocomposite can release the absorbed CO₂ at 500 °C in larger amounts of 66 wt%. CaAcac-modified SMP nanocomposites thus show a higher potential for CO₂ capture and release applications at moderate temperatures of 500 °C compared to CaOH-modified nanocomposites.