A new electrolyte for molten carbonate decarbonization

The molten Li₂CO₃ transformation of CO₂ to oxygen and graphene nanocarbons (GNCs), such as carbon nanotubes, is a large scale process of CO₂ removal to mitigate climate change. Sustainability benefits include the stability and storage of the products, and the GNC product value is an incentive for carbon removal. However, high Li₂CO₃ cost and its competitive use as the primary raw material for EV batteries are obstacles. Common alternative alkali or alkali earth carbonates are ineffective substitutes due to impure GNC products or high energy limitations. A new decarbonization chemistry utilizing a majority of SrCO₃ is investigated. SrCO₃ is much more abundant, and an order of magnitude less expensive, than Li₂CO₃. The equivalent affinities of SrCO₃ and Li₂CO₃ for absorbing and releasing CO₂ are demonstrated to be comparable, and are unlike all the other alkali and alkali earth carbonates. The temperature domain in which the CO₂ transformation to GNCs can be effective is <800 °C. Although the solidus temperature of SrCO₃ is 1494 °C, it is remarkably soluble in Li₂CO₃ at temperatures less than 800 °C, and the electrolysis energy is low. High purity CNTs are synthesized from CO₂ respectively in SrCO₃ based electrolytes containing 30% or less Li₂CO₃.