Influence of transition metal additives and temperature on the rate of organohalide reduction by granular iron: Implications for reaction mechanisms
Influence of transition metal additives and temperature on the rate of organohalide reduction by granular iron: Implications for reaction mechanisms
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DOI：
10.1016/j.apcatb.2007.06.003
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发表时间：
2007-11
影响因子：
22.1
通讯作者：
Stephen J. Bransfield;David M. Cwiertny;K. Livi;D. Fairbrother
中科院分区：
文献类型：
--
作者：
Stephen J. Bransfield;David M. Cwiertny;K. Livi;D. Fairbrother
本研究提供了颗粒铁还原有机卤化物的机理见解，以及当过渡金属添加到颗粒铁表面时通常观察到的速率增强的起源。利用CuCl2， k2pdcl4和K2PtCl4的逐级位移电镀，制备了不同的双金属和三金属还原剂，并使用包括能量过滤透射电镜（EFTEM）在内的一套分析技术对其进行了表征。用三金属进行的批量研究结果表明，1,1,1-三氯乙烷（1,1,1- tca）还原反应活性的增强是由过渡金属添加剂在液/固界面的化学特性控制的。涉及铁和双金属的温度依赖性研究表明，1,1,1- tca还原率随着温度的升高呈指数增长。随着1,1,1- tca还原的总速率增加，还观察到产品分布向更充分氢化产品的系统转变。总的来说，这些结果支持了最近的研究，这些研究表明原子氢参与了颗粒铁和双金属还原剂对烷基多卤化物的还原。
This study provides mechanistic insights into the reduction of organohalides by granular iron as well as the origin of the rate enhancements typically observed when transition metals are added to the surface of granular iron. Using step-wise displacement plating of CuCl2, K2PdCl4and K2PtCl4, different bimetallic and trimetallic reductants were prepared and characterized using a suite of analytical techniques that included energy filtered transmission electron microscopy (EFTEM). Results obtained from batch studies with the trimetals indicate that reactivity enhancements of 1,1,1-trichloroethane (1,1,1-TCA) reduction are controlled by the chemical identity of the transition metal additive at the liquid/solid interface. Temperature-dependent studies involving iron and bimetals revealed that rates of 1,1,1-TCA reduction increased exponentially with increasing temperature. A systematic shift in product distribution towards more fully hydrogenated products was also observed as the overall rate of 1,1,1-TCA reduction increased. Collectively, these results support recent studies, which suggest that atomic hydrogen is involved in the reduction of alkyl polyhalides by granular iron and bimetallic reductants.