MgCl_2-KCl-NaCl-CaCl_2熔盐电解镁机理  

Mechanism of Electrolysis of Magnesium Chloride in MgCl_2-KCl-NaCl-CaCl_2 Molten Salt

作　　者：陈野 叶克 

机构地区：[1]哈尔滨工程大学超轻材料与表面技术教育部重点实验室,哈尔滨150001

出　　处：《应用化学》2008年第12期1409-1412,共4页Chinese Journal of Applied Chemistry

基　　金：国家高技术研究发展计划(“八六三”计划,2006AA03Z510);黑龙江省科技攻关基金(GC06A212)资助项目

摘　　要：在725℃温度下，对MgCl2-KCl-NaCl-CaCl2熔盐体系进行电解。研究结果表明，镁电解过程中阴极过电压ηc只有12～51mV，电解过程的过电压主要是由阳极引起的；阴极还原过程的极限扩散电流密度id为1．56A／cm^2；镁离子阴极放电反应的电子转移数为1．98：2个电子转移步骤之前存在着前置转化步骤MgCl^＋→Mg^2＋ ＋Cl^-。应用循环伏安法对4种不同配比下的镁离子行为进行的研究结果表明，CaCl2质量分数从10％增加到40％，维持MgCl2质量分数为10％以及NaCl与KCl的质量比为6：1不变，随着CaCl2质量分数的增加，镁离子结合成不易移动的络合阴离子，镁离子迁移的电流分数减小，镁离子的析出电位从-1．595V逐渐负移至与钙、钠共同沉积，阴极峰值电流Ipc值逐渐增大，阳极峰值电位与阴极峰值电位之差的绝对值｜φpa-φpc｜逐渐增大，阴极放电反应的可逆性逐渐降低。At 725 ℃, MgCl2-KCl-NaCl-CaCl2 molten salt was used for the electrolysis of magnesium chloride. Results show that in the course of magnesium electrolysis, cathode overvoltage ηc is not large, only 12-51 mV, the overvohage of the electrolysis process is mainly caused by the anode; the diffusion-limited current id of the cathodic process is 1.56 A/cm^2 ; the number of electron transfer of the cathodic process is 1.98; while there is a pre-conversion step MgCl^＋ = Mg^2＋ ＋ Cl ^- before the reversible electron transfer step. CV was used to study magnesium ions behavior in the molten salt electrolyte with four different ratios of CaCl2. With changing CaCl2 from 10 percent to 40 percent, while maintaining MgCl2 to be 10 percent and the mass ratio of NaCl and KCl to be 6 ： 1, as the amount of CaCl2 increased, magnesium ions integrate into the complexing anions, which are not easy to move. As a result, the migration current of magnesium ions decreases, the magnesium ions deposition potential gradually moves to the negative direction from - 1. 595 V to which codeposition of magnesium with Ca and Na takes place, cathodic peak current Ipc gradually increases, the absolute value of the difference between anodic peak potential and cathodic peak potential ｜φpa-φpc｜ gradually increases, and the reversibility of cathode discharge reaction gradually lowers.

关 键 词：熔盐 电解 镁 阴极过程 

分 类 号：O646.5[理学—物理化学]