Thermodynamic Investigations for Combustion-Assisted Synthesis of Lithium Orthosilicate Powders

Abstract

The study investigates the combustion-assisted synthesis of lithium orthosilicate (Li₄SiO₄) powders for potential CO₂ capture applications. Technical-grade lithium carbonate and metallic silicon powders were used as starting materials. Synthesis conditions were explored across temperatures ranging from 500 to 900 °C and different holding durations. Thermodynamic modeling using FactSage 8.2 software suggested that Li₄SiO₄ production is feasible at temperatures of 700 °C and higher with metallic silicon as the silicon source, which was confirmed experimentally. Characterization of the synthesized powders involved X-ray diffraction, specific surface area determination, particle size distribution analysis, scanning electron microscopy, and CO₂ uptake tests. Despite having the lowest Li₄SiO₄ content as 83.7%, the sample synthesized at 700 °C with 45 min of holding time showed the best CO₂ uptake performance as 12.80 wt% while having the lowest crystallite size value (126.58 nm), the highest specific surface area value (4.975 m²/g) and the lowest average particle size value (10.85 µm) which are highly effective on the CO₂ uptake performance of such solid sorbents. The study concludes that while challenges remain in achieving optimal CO₂ capture performance, it lays a foundation for utilizing lithium orthosilicate in carbon capture applications.

Graphical Abstract