离子液体中置换法制备镁/铜双金属粉的动力学研究

Kinetics of Preparation of Mg/Cu Bimetallic Powder in Ionic Liquid by Displacement Method

研究了氯代1-丁基-3-甲基咪唑（BMIC）离子液体中镁置换铜制备镁/铜双金属粉的动力学行为,探讨了搅拌速率、反应温度、铜离子浓度和镁粉颗粒大小等参数对反应速率常数的影响。动力学数据结果表明,在离子液体中镁置换铜的反应符合一级反应速率方程。反应速率常数随着搅拌速率增加、反应温度升高、铜离子浓度降低和镁粉粒径减小而增大。搅拌可使反应速率常数增大1倍左右;Cu（II）离子浓度较小时,反应速率常数随Cu（II）离子浓度的增加而迅速减小,当Cu（II）离子浓度增大到0.25 mol·L-1时,速率常数的减小趋势逐渐变缓;镁粉粒径范围从50~74μm增加到74~100μm,置换反应的速率常数从0.334 h-1减小到0.255 h-1;反应速率常数与反应温度的关系符合阿伦尼乌斯方程,求得置换反应表观活化能为13.6 k J·mol-1,说明置换过程受扩散控制。此外,Evans图研究也表明,置换反应受Cu（II）离子向电极表面扩散过程控制。这一结果与动力学数据的实验结果完全一致。

The kinetics of preparation of Mg/Cu bimetallic powder in 1-butyl-3-methylimidazolium chloride （BMIC） ionic liquid by displacement method was studied. The influence of initial concentration of copper ions, reaction temperature, grain size of magnesium and stirring speed on the reaction rate constant was investigated. Dynamic results indicated that the replacement reaction followed first order reaction kinetics equation, and the reaction rate constant increased with the increase of temperature and stirring rate and the de- crease of Cu（II） concentration in ionic liquid. The reaction rate constant could be increased by about one time through stirring. As the concentration of Cu（II） was lower, the reaction rate constant quickly decreased with the concentration of Cu（II） increasing. When the concentration of Cu（II） increased to 0.25 mol＇L-1, the reaction rate constant decreased slowly as the concentration of Cu（II） further increased. With the grain size of magnesium increasing from 50 N 74 μm to 74 ~ 100 μm, the reaction rate constant decreased from 0. 334 to 0. 255 h - 1. The temperature dependence of reaction rate constant followed Arrhenius equation. The apparent activation energy of the reaction was 13.6 kJ.mol- l and the replacement process was controlled by diffusion. Furthermore, Evans diagram showed that the replacement process was controlled by the diffusion of Cu（II） to the surface of the electrode. These results were entirely consistent with the experimental results of kinetic data.