汽车失效催化剂中铑的浸出动力学研究

Leaching Kinetics of Rhodium from Spent Automotive Catalyst

面对全球铂族金属(PGMs)资源进一步匮乏的严峻形势及工业的快速发展,人们对PGMs的需求量也日益增加,报废的汽车催化剂成为了PGMs最重要的二次资源,在其回收方法中,湿法浸出得到了研究者的广泛关注,但其中金属铑的回收率普遍偏低,通过考察浸出反应液固比、氧化剂氯酸钠用量、温度、初始氢离子浓度、初始氯离子浓度对铑浸出的影响,研究了汽车失效催化剂在HCl-H2SO4-Na Cl O3体系中铑的浸出反应动力学。结果表明,汽车失效催化剂中铑的浸出遵循"未反应核缩减"模型,受化学反应控制;提高反应温度,初始氢离子浓度及初始氯离子浓度均可提高铑的浸出率并加速铑的浸出速率;液固比及氧化剂Na Cl O3用量对浸出速率影响不明显;采用阿伦尼乌斯公式求出反应活化能为66.719 k J·mol-1,氢离子反应级数为0.779,氯离子反应级数为0.296,3个动力学参数的拟合曲线的相关系数均在0.97以上。从汽车失效催化剂中浸出铑的动力学研究为以后工业实践中处理回收铂族金属提供一定的借鉴意义。

Recycling platinum group metals（ PGMs） from spent automobile catalysts which have become the most important PGMs secondary resources is becoming quite important,due to the limitation of natural resource deposits of PGMs and the rapid industrial development. Among the processes of PGMs＇ recycling from spent automobile catalysts,the hydrometallurgical leaching drew extensive concerns,but the recovery of Rh was the most inefficient. Based on the effects of liquid-solid rate,sodium chlorate,reaction temperature,[H＋]concentration,[Cl-]concentration on leaching of rhodium,the leaching kinetics of rhodium extracted from spent automotive catalyst in HCl-H2SO4-Na Cl O3 medium was studied. The results showed that the leaching process followed the shrinking core model,which indicated that the control factor of the leaching process was the surface reaction. Enhancing the leaching temperature,initial [H＋]and initial [Cl-]would accelerate the speed of rhodium leaching and raise the leaching rate. The ratio of liquid to solid and the dosage of oxidant Na Cl O3 had few influences on the leaching rate of rhodium. The apparent activation energy was determined as66. 719 k J·mol- 1within the selected temperature range by Arrhenius equation. The apparent reaction progressions of [H＋] and[Cl-]were 0. 779 and 0. 296,respectively. What was more,the correlation coefficients fitting experimental data were more than0. 97. The kinetics study of leaching rhodium from spent automotive catalyst provided some references for the recycle of platinum group metals in industry practice.