高氯酸体系中肼为还原剂催化还原U(Ⅵ)的反应动力学  

Catalytic Reaction Kinetics of U(Ⅵ) With Hydrazine on Platinum Black in Perchloric Acid Media

作　　者：李斌[1] 何辉[1] 张秋月[1] 丁伯发[1] 王亮[1] 唐洪彬[1] 

机构地区：[1]中国原子能科学研究院放射化学研究所,北京102413

出　　处：《核化学与放射化学》2012年第4期213-217,共5页Journal of Nuclear and Radiochemistry

摘　　要：开展了高氯酸体系中以肼为还原剂,铂黑为催化剂催化还原U(Ⅵ)的动力学研究。通过考察U(Ⅵ)浓度、肼浓度、酸度以及催化剂用量等条件对反应过程的影响,确定了该反应的初始动力学速率方程为-dc(UO22+)/dt=kc0.39(UO22+)c0.36(N2H5+)c-0.51(H+),在60℃、固液比0.002kg/L时,速率常数k=3.2×10-3(mol/L)0.76/min。研究了温度对反应速率的影响,结果表明,在20～75℃范围内,随着温度升高,反应速率加快,反应过程由化学反应控制转变为扩散控制过程。并在此基础上推测了可能的反应机理,认为肼在催化剂表面的吸附分解是整个反应的控制步骤。The kinetics of platinum-catalyzed reduction of U（VI） with hydrazine in perchloric acid media was studied. By investigating the influence of U （VI） concentration, hydrazine concentration, acidity and catalyst amounts （S/L） on the reaction, the reaction rate equation is obtained： -dc（UO22＋）/dt=kc0.39（UO22＋）c0.36（N2H5＋）c-0.51（H＋）,, and the rate constant is k=3.2×10-3（mol/L）0.76/minmin at 60 ℃ and the solid-to-liquid ratio of 0. 002 kg/L. The effect of temperature was also investigated. The results show that while increasing the temperature, the reaction accelerates and the reaction process shifts from reaction-controlled to diffusion- controlled. Based on the above results, a possible reaction mechanism with the dissociation of adsorbed hydrazine on the catalyst as the the control step, is explored.

关 键 词：肼 铂黑 铀(Ⅵ) 催化还原 

分 类 号：O643.12[理学—物理化学]