Synthesis of Lithium Manganese Oxide and Ti‐Substituted LMO Sorbents for Lithium Extraction in a Spray‐Drying Process

Lithium manganese oxides (LMO) are highly promising sorbents for lithium extraction from Li <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:semantics> <mml:mrow><mml:msup><mml:mrow></mml:mrow> <mml:mo>+</mml:mo></mml:msup> </mml:mrow> <mml:annotation>$^{&#x00026;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;plus;}$</mml:annotation></mml:semantics> </mml:math> -containing brines with high salt contents due to their high sorption capacity and high selectivity toward lithium. However, conventional synthesis routes are limited in scale. Therefore, a novel spray-drying method is presented herein, enabling a scalable synthesis of LMO sorbents for Li <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:semantics> <mml:mrow><mml:msup><mml:mrow></mml:mrow> <mml:mo>+</mml:mo></mml:msup> </mml:mrow> <mml:annotation>$^{&#x00026;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;plus;}$</mml:annotation></mml:semantics> </mml:math> extraction. The ion-exchange material is studied in both synthetic LiCl solutions and two different geothermal brines from the Upper Rhine Valley, demonstrating improved Li selectivity and extraction capabilities compared to materials from hydrothermal synthesis approaches. The extraction behavior in relevant mildly acidic environments is studied in detail. Further material improvements are achieved by substituting a fraction of Mn by Ti, which greatly reduced the dissolution of manganese during acid treatment in the first 5 extraction cycles from 5.6% to only 1.8%. In addition, the maximum sorption capacity of the Ti-substituted LMO (LMTO) can be further increased from 5.05 mmol g <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:semantics> <mml:mrow><mml:msup><mml:mrow></mml:mrow> <mml:mrow><mml:mo>-</mml:mo> <mml:mn>1</mml:mn></mml:mrow> </mml:msup> </mml:mrow> <mml:annotation>$^{- 1}$</mml:annotation></mml:semantics> </mml:math> for LMO (35.1 mg g <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:semantics> <mml:mrow><mml:msup><mml:mrow></mml:mrow> <mml:mrow><mml:mo>-</mml:mo> <mml:mn>1</mml:mn></mml:mrow> </mml:msup> </mml:mrow> <mml:annotation>$^{- 1}$</mml:annotation></mml:semantics> </mml:math> ) to 5.66 mmol g <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:semantics> <mml:mrow><mml:msup><mml:mrow></mml:mrow> <mml:mrow><mml:mo>-</mml:mo> <mml:mn>1</mml:mn></mml:mrow> </mml:msup> </mml:mrow> <mml:annotation>$^{- 1}$</mml:annotation></mml:semantics> </mml:math> for LMTO (39.3 mg g <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:semantics> <mml:mrow><mml:msup><mml:mrow></mml:mrow> <mml:mrow><mml:mo>-</mml:mo> <mml:mn>1</mml:mn></mml:mrow> </mml:msup> </mml:mrow> <mml:annotation>$^{- 1}$</mml:annotation></mml:semantics> </mml:math> ) under optimized m/V ratios. Hence, the results reported herein present a pathway toward LMO-based ion-exchange materials for the direct lithium extraction on an industrial scale.