Surface and bulk carbonate formation in calcium oxide during CO2 capture. (15th September 2017)

• Record Type: Journal Article
• Authors: Mutch, Greg A.; Anderson, James A.; Vega-Maza, David
• Is Part Of: Applied energy. Volume 202(2017)
• Page Start: 365
• Page End: 376
• Publication Date: 2017-09-15
• Subjects: Calcium looping -- Surface chemistry -- In-situ infrared spectroscopy -- Carbon capture, utilisation and storage (CCUS) -- Carbonate formation -- Hydration; Power (Mechanics) -- Periodicals; Energy conservation -- Periodicals; Energy conversion -- Periodicals; 621.042
• DOI: 10.1016/j.apenergy.2017.05.130
• Languages: English
• ISSNs: 0306-2619

Abstract

Graphical abstract: Highlights: In-situ infrared used to distinguish surface and bulk carbonate formation. Influence of hydration on surface chemistry of CaO investigated. CaO from Ca(OH)2 presents more highly reactive sites than CaO from CaCO3. Water or hydroxyl functionality initiates bulk carbonate formation at 300 °C. Abstract: Calcium looping (CaL), the cyclic carbonation and calcination of limestone, is a prominent carbon capture option considering reduced parasitic energy consumption compared to amine scrubbing. The main issue preventing application is sorbent performance decay during cycling. Therefore hydration and extended carbonation reactivation strategies, as well as synthetic approaches to enhance or sustain reactivity, are of interest. Results of an investigation are presented on the impact of reactivation strategies on carbonate formation through detailed study using in-situ infrared spectroscopy. Surface and bulk carbonate formation regimes were readily distinguished allowing the influence of temporal, hydration and thermodynamic conditions within each regime to be studied. Surface chemistry of CaO during two initial cycles was shown to change. Significantly, it was shown that the CaO surface produced from the calcination of Ca(OH)2 possessed more highly reactive sites compared to the surface produced from CaCO3 . The presence of water enhanced bulk carbonate formation at 300 °C and influenced the complexation of surface carbonates during looping. The results are of interest in the CaL community, offering molecular scale explanations for macroscale observations, whilst also informing on the role of humidity in direct air capture and sorption enhanced reaction processes.