Study of Speciation and Transport Properties for Different Compositions of Carbonates in Li2CO3 -Na2CO3 and Li2CO3 -K2CO3 Binary Systems at High Temperature in Molten State

Molten alkali carbonates play a central role in carbon-capture technologies. To characterize the structural and transport properties, we used NMR, pulse field gradient (PFG) NMR, electrical impedancemetry, and molecular dynamics simulation. Different compositions in Li2CO3-Na2CO3 and Li(2)CO(3)K2CO(3) binary systems at 1003 K have been studied. The NMR measurements confirmed only the presence of anionic species CO23 - whatever the composition. Some structural evolution of K+ and Li+ cations around the oxygen was detected in the composition Li2CO3-K2CO3. With the addition of K2CO3 in the carbonate mixture, the interaction between the charge carriers present in the liquid increases and results in a decrease of electrical conductivity.

Automated summary

Molten alkali carbonates, including Li2CO3-Na2CO3 and Li2CO3-K2CO3 binary systems, were studied using various techniques such as NMR, PFG NMR, electrical impedancemetry, and molecular dynamics simulation. The presence of CO23 - anionic species was confirmed by NMR measurements regardless of the composition. Structural changes of K+ and Li+ cations around the oxygen were observed in Li2CO3-K2CO3 composition. The addition of K2CO3 in the carbonate mixture increased the interaction between charge carriers and decreased electrical conductivity.