Carbon capture in molten salts

Abstract

Capture and storage of fossil carbon emitted to the atmosphere from anthropogenic sources has been identified as a key technology for keeping humaninduced global warming below 2°C. Available technologies have not achieved widespread impact due to costs related to increased energy consumption and expensive, large process equipment. Here, we show how molten inorganic halide salt-based mixtures containing CaO may be utilized for selective capture and subsequent controlled release of carbon dioxide from diluted flue gases. Highly efficient absorption is demonstrated in a fluoride-based liquid, absorbing close to 100% of the CO 2 from a simulated flue gas with an absorbing column height of only 10 cm. Greater than 90% carbonation with >80% regeneration to CaO was recorded. Excellent cyclability has been achieved with a chloride-based liquid with 60% carbonation and 100% regeneration to CaO during four cycles. The high efficiencies may enable extraction of CO 2 from highly diluted gas mixtures.

Molten salts-modified MgO-based adsorbents for intermediate-temperature CO2 capture: A review

“…Molten salts [20,21] , such as alkali metal nitrates, alkali and alkali earth metal carbonates are commonly applied in solar energy utilization due to its advantages such as thermodynamic stability up to high temperatures, low pressure at the operating temperature and wide range of solubility [22] . Considerable research efforts have been devoted to the fabrication of molten salts promoted MgO-based adsorbents due to their outstanding CO 2 capture performance, excellent regenerability and rather higher thermal stability, compared with other modification methods.…”

Reactivity of CaO with CO2 in molten CaF2–NaF: formation and decomposition of carbonates

“…CaF 2 -NaF and CaF 2 -LiF eutectic mixtures have been used. The results indicate that the highest carrying capacity (0.722-0.743 g CO 2 /g CaO) may be achieved with the CaO-CaF 2 /NaF system due to thermodynamically stable Na 2 CO 3 being formed through an ion exchange reaction [11,14]. Studies of cyclic CO 2 absorption/desorption by 5.32 wt% CaO in molten CaCl 2 showed a stable carrying capacity of 0.504 g CO 2 /g CaO [12].…”

“…Studies of cyclic CO 2 absorption/desorption by 5.32 wt% CaO in molten CaCl 2 showed a stable carrying capacity of 0.504 g CO 2 /g CaO . In this case, the decomposition of the formed carbonates proceeded rapidly and completely, but when using alkali and alkaline‐earth metal halide salts, full decomposition of the carbonates formed in the melt could not be achieved .…”

“…Reactivity of CaO with CO 2 in molten CaF 2 -NaF: formation and decomposition of carbonates decomposition of the formed carbonates proceeded rapidly and completely, but when using alkali and alkaline-earth metal halide salts, full decomposition of the carbonates formed in the melt could not be achieved [11].…”

Insights into Carbon Nanotubes and Fullerenes in Molten Alkali Carbonates

“…22,23 Likewise, MACs have been proposed for gas separation operations, in particular for CO 2 capture and valorisation, 24 which is of great relevance for CO 2 abatement, both using MCFCs 25,26 and absorption on the liquid phase. 27,28 Moreover, MACs -based membranes for gas (CO 2 ) separation applications have been reported considering several supports. 29,30,31 In particular, MACs on 2D materials such as graphene have showed remarkable and useful properties.…”