层状钠锰氧化物的制备及离子交换反应动力学

Preparation of Layered Sodium Manganese Oxide and Ion Exchange Reaction Kinetics of Lithium

用固相合成法制备了层状前驱体钠锰氧化物 (Na0 .67[Mn0 .90 Mg0 .10 ]O2 ) ,研究了它在LiCl·H2 O LiNO3 熔融盐体系和LiBr·2H2 O正己醇溶液体系中与Li+ 的交换反应动力学特点。采用XRD技术检测前驱体及交换产物的浓度变化。用插层反应动力学模型算出不同反应温度的熔融盐体系和正己醇体系中离子交换反应的表观速率常数 ,分别为 0 1 2 7～ 0 2 0 8s-1( 2 60～ 3 0 0℃ )和 5 93× 1 0 -4～ 3 94× 1 0 -3 s-1( 4 0～ 80℃ ) ;反应级数为1 2 4～ 1 3 0和 0 92～ 1 1 3 ;反应活化能为 3 1 2和 43 7kJ/mol。讨论了 2个体系动力学行为的异同点 ,初步确定Li+ →Na+ 过程是离子交换反应速率的控制步骤。

Layered sodium manganese oxide Na 0.67 \[Mn 0.90 Mg 0.10 \]MgO 2 was prepared by solid state reaction, and the kinetics of ion exchange intercalation reaction of Li + into layered sodium manganese oxide was studied . The reaction has been investigated in two systems: n hexanol solution system and molten salt system. The apparent rate constant?reaction order and activation energy of the ion exchange reaction were calculated. An intercalation kinetic model has been used in the study on ion exchange intercalation reaction. The concentration changes of the precursor and product were monitored according to 2 θ angle of \ peak in powder XRD patterns. The rate constants in molten salt were calculated to be 0 127～0 208 s -1 (260～ 300 ℃ ), much greater than those in n hexanol solution system, 5 93×10 -4 ～3 94×10 -3 s -1 (40～ 80 ℃ ). The reaction orders for the two systems are all about 1. The calculated values of the apparent activation energy are 31 2 kJ/mol(for molten salt) and 43 7 kJ/mol(for n hexanol solution), respectively.