Synthesis and evaluation as CO2 chemisorbent of the Li5(Al1-xFex)O4 solid solution materials: Effect of oxygen addition

• Published in: Journal of energy chemistry 2017-09, Vol.26 (5), p.948-955
• Main Author: Paulina Olavarría Elizabeth Vera Enrique J.Lima Heriberto Pfeiffer
• Format: Article
• Language: English
• Subjects: CO2 chemisorption; Lithium aluminate; Solid solution; Thermogravimetry
• ISSN: 2095-4956
• DOI: 10.1016/j.jechem.2017.08.002

Pentalithium aluminate（β-Li5AlO4） and the corresponding iron-containing solid solution(Li5(Al1-xFex)O4)were synthetized by solid-state reaction. All the samples were characterized structural and microstructurally by X-ray diffraction, solid-state nuclear magnetic resonance, scanning electron microscopy, N2 adsorption-desorption and temperature-programmed desorption of CO2. Results showed that 30 mol% of iron can be incorporated into the β-Li5AlO4 crystalline structure at aluminum positions. Moreover, iron addition induced morphological and superficial reactivity variations. Li5(Al1-xFex)O4 samples chemisorbed CO2 between 200 and 700 °C, where the superficial chemisorption presented the highest enhancement,in comparison to β-Li5AlO 4. Additionally, Li5(Al1-xFex)O4 samples sintered at higher temperatures thanβ-Li5AlO4. Isothermal CO2 chemisorption experiments of β-Li5AlO4 and Li5(Al1-xFex)O4 were fitted to a first order reaction model, corroborating that iron enhances the CO2 chemisorption, kinetically. When oxygen was added to the gas flow, CO2 chemisorption process was mainly enhanced between 400 and 600 °C for the Li5(Al0.8Fe0.2)O4 sample in comparison to β-Li5AlO4. Hence, Li5(Al1-xFex)O4 solid solution presented an enhanced CO2 chemisorption process, in the presence and absence of oxygen, in comparison to β-Li5AlO4.