Connecting the Morphological and Crystal Structural Changes during the Conversion of Lithium Hydroxide Monohydrate to Lithium Carbonate Using Multi-Scale X-ray Scattering Measurements

Greeshma Gadikota

doi:10.3390/min7090169

Abstract

While CO2 storage technologies via carbon mineralization have focused on the use of earth-abundant calcium- and magnesium-bearing minerals, there is an emerging interest in the scalable synthesis of alternative carbonates such as lithium carbonate. Lithium carbonate is the carbonated end-product of lithium hydroxide, a highly reactive sorbent for CO2 capture in spacecraft and submarines. Other emerging applications include tuning the morphology of lithium carbonates synthesized from the effluent of treated Li-bearing batteries, which can then be reused in ceramics, glasses, and batteries. In this study, in operando Ultra-Small-Angle, Small-Angle, and Wide-Angle X-ray Scattering (USAXS/SAXS/WAXS) measurements were used to link the morphological and crystal structural changes as lithium hydroxide monohydrate is converted to lithium carbonate. The experiments were performed in a flow-through reactor at PCO2 of 1 atm and at temperatures in the range of 25–500 °C. The dehydration of lithium hydroxide monohydrate to form lithium hydroxide occurs in the temperature range of 25–150 °C, while the onset of carbonate formation is evident at around 70 °C. A reduction in the nanoparticle size and an increase in the surface area were noted during the dehydration of lithium hydroxide monohydrate. Lithium carbonate formation increases the nanoparticle size and reduces the surface area.

Highlights

Carbon mineralization, which involves the conversion of CO2 to carbonates that are thermodynamically stable, environmentally benign, and insoluble in water, has been proposed as a pathway to safely and permanently store CO2 via natural and engineered pathways [1,2,3,4,5,6,7,8,9,10]
While various earth-abundant calcium and magnesium silicates have been extensively investigated for the permanent storage of CO2 [3,4,5,7,11,12] given their availability in nature [13,14,15], there is an increasing interest in the scalable synthesis of alternative carbonates such as lithium carbonates
Lithium carbonate is the end-product of the carbonation of lithium hydroxide, a highly reactive sorbent for CO2 capture in spacecraft and submarines

Summary

Introduction

Carbon mineralization, which involves the conversion of CO2 to carbonates that are thermodynamically stable, environmentally benign, and insoluble in water, has been proposed as a pathway to safely and permanently store CO2 via natural and engineered pathways [1,2,3,4,5,6,7,8,9,10]. While various earth-abundant calcium and magnesium silicates have been extensively investigated for the permanent storage of CO2 [3,4,5,7,11,12] given their availability in nature [13,14,15], there is an increasing interest in the scalable synthesis of alternative carbonates such as lithium carbonates. Some of the factors that influence the morphology of lithium carbonate are the reactive precursors and water. Previous studies have suggested that the kinetics of LiOH conversion to lithium

Methods

Discussion

Conclusion