Collaborative Research: Elucidating cycling and deactivation mechanisms of earth-abundant CO2 looping sorbents under precise temperature control

About This Grant

Calcium oxide is a highly abundant, inexpensive material that can be used to capture CO2 from the atmosphere and from combustion exhaust. The key drawback to using calcium oxide is that the material undergoes changes during its use, which reduces its service lifetime. This project will use computational modeling and experiments to study the fundamental chemical reaction between CO2 and calcium oxide. The results of these studies will be used to design processes that increase the amount of CO2 calcium oxide absorbs in practice and to increase calcium oxide’s service lifetime. The research team will collaborate with local middle and high school teachers to develop new educational activities and will introduce students and teachers to concepts in materials science, energy storage, and CO2 capture. This proposal integrates computational modeling with atomic-scale in situ electron microscopy to advance understanding of chemical ‘looping’ reactions between CO2 and scalable earth-abundant sorbent materials—namely CaO-based sorbents. The guiding thesis is that sorbent cycle life and CO2 uptake capacity can be extended through rational design of thermal schedules and compositions. This ‘precision temperature control’ approach is expected to thermally activate calcination (sorbent regeneration) and carbonation reactions without excessive heating known to cause sorbent deactivation by particle sintering and surface area loss. By coupling atomic-scale simulations and in situ experiments under reaction conditions, thermodynamic driving forces and key pathways governing kinetics will be elucidated, enabling design of sorbents, heat treatments, and efficient thermal processes for long sorbent life and compatibility with concentrated solar thermal energy. Research is structured in four aims. Aim 1 is to develop a multiscale computational framework to obtain atomic-level mechanistic understanding of CaO+CO2↔CaCO3 looping cycles and validate the framework experimentally using atomic-resolution and in situ gas cell (scanning) transmission electron microscopy. Aim 2 is to extend and experimentally validate the modeling framework to elucidate the role of key humidity derived calcium hydroxide (Ca(OH)2) intermediates on looping reaction mechanisms and cycling stability. Aim 3 is to extend and experimentally validate the framework to assess the role of performance-enhancing chemical additives/dopants on looping reactivity and cycling stability. Aim 4 is to extend and validate the framework to assess the role of particle-particle GB interfaces on looping reactivity and cycling stability. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.