摘要
在酸性介质中用氧化还原滴定法研究了铈（Ⅳ）离子在铬（Ⅲ）离子催化作用下，于30～45℃区间氧化甲酸的反应动力学．结果表明反应对铈（Ⅳ）和甲酸均为一级，准一级速率常数kobs随催化剂[Cr（Ⅲ）]增加而增大，亦随[H^＋]增加而增大，而随[HSO^-4]增加而减小．在氮气保护下，反应能引发丙烯腈聚合，说明在反应中有自由基产生．提出了催化剂、底物和氧化剂间生成双核配合物的反应机理．通过kobs与HSO4的依赖关系，并结合Ce（Ⅳ）在溶液中的平衡，认为本反应的动力学活性物种是Ce（SO4）2，还计算出一些速率常数及相应的活化参数．
The kinetics of chromium（ Ⅲ） catalysed oxidation of formic acid by cerium（ Ⅳ ） in aqueous sulphuric acid medium was studied by titrimetric techniques of redox in the temperature range of 30- 45 ℃. The order is found to be unity with respect to both Ce（Ⅳ） and formic acid. It was found that the pseudo first order （[HCOOH]）〉〉[Ce（Ⅳ）]） rate constants kobs increases with the increase of [Cr（Ⅲ ） ] and [H^＋], but decreases with the increase of [ HSO4 ]. Under the protection of nitrogen the reaction system induces polymerzation of acrylonitrile indicating the generation of free radicals. Formation of a dinuclear complex involving the oxidant, catalyst and the substrate has been proposed in the reaction mechanism. From the relation between kobs and [HSO4 ], Ce（SO4）2 has been found as the kinetically active species. Some rate constants together with activation energy were evaluated.
出处
《河北大学学报（自然科学版）》
CAS
北大核心
2008年第1期57-62,73,共7页
Journal of Hebei University(Natural Science Edition)
基金
河北大学自然科学基金资助项目(2003Z09)
