abstract
Alkali metal nitrates were successfully used as starting chemicals in the production of composite CO2 separation membranes. The easy conversion of nitrates into carbonates after high temperature annealing in CO2 is confirmed using techniques like FTIR (Fourier transform infrared) or selective NO3- electrodes. This conversion shows a step like increase at temperatures in the order of 600 ?, consistent with target utilization temperatures for these membranes. A second but equally relevant consequence of this novel route is the formation of significant concentrations of oxide ions in the molten phase, able to boost the membrane performance, where the ceramic phase modest oxide ion conductivity is rate determining. At 650 ?, a CO2 separation flux enhancement in the order of 60% was reached using nitrates as starting chemicals. A deep analysis of the oxide ion content in molten phases using a variety of analytical techniques, confirmed the specific features of the nitrates as starting chemicals but also showed that even when carbonates are used as precursors, the role of oxide ions in the molten phase can increase significantly the membrane performance.
keywords
HIGH-TEMPERATURE STABILITY; CARBON-DIOXIDE; ELECTROCHEMICAL PERMEABILITY; OXYGEN PERMEABILITY; POTASSIUM-NITRATE; ELECTROLYTES; CONDUCTIVITY; SOLUBILITY; OXIDE; RAMAN
subject category
Engineering; Polymer Science
authors
Starykevich, M; Jamale, A; Yasakau, KA; Marques, FMB
our authors
acknowledgements
Work supported by FCT-2020.00625.CEECIND grant and CICECO- Aveiro Institute of Materials (FCT Ref. UID/CTM/50011/2019) , financed by national (Portugal) funds through the FCT/MCTES, and when applicable co -financed by FEDER under the COMPETE 2020 Program. Specific support (AJ) provided by national funds (OE) , through FCT, IP, in the scope of the framework contract foreseen in the numbers 4, 5, and 6 of the article 23, of the Decree -Law 57/2016, of August 29, changed by Law 57/2017, of July 19.