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X号君

铜虫 (小有名气)

应助: 4 (幼儿园)
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虫号: 1145021
注册: 2010-11-12
性别: GG
专业: 催化化学

[求助] 动力学同位素效应（CH4/CD4）的原理

我是做甲烷干重整催化剂反应课题的。最近看一篇关于动力学同位素效应的文献。其中讲到当用CD4取代CH4时，CO的生成速率会大幅降低，从而说明CH4中C-H健的断裂是一个缓慢的过程。反之，则说明是一个快速的过程。请教各位一下这是为什么？（原文：The results of the kinetic isotope effect for the reaction of carbon dioxide reforming of methane to synthesis gas over the Ni/La203 and Ni/'y-A1203 catalysts are presented in table 1. Before switching the mixture from CHa/COz/He to CDa/CO2/He, the reaction was run for at least 5 h to reach stable performance of the Ni/ La203 catalyst and pseudo-stable performance of the Ni/-A1203 catalyst. It is shown in table 1 that the rate of CO formation (Rco) over the Ni/La203 catalyst is significantly reduced upon replacing CH4 with CD4 in the feed mixture, indicating that breaking of the C-H bond of the CH4 molecule is a slow step over the Ni/ La203 catalyst.
Only a small reduction in the rate of CO formation, by a factor of 1.02-1.08, was detected over the Ni/ A1203 catalyst upon switching CH4 / CO2 to CD4 / CO2, suggesting that methane activation over the Ni/A1203 catalyst is a fast step.）

[ Last edited by X号君 on 2013-3-2 at 12:39 ]

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