Kinetics and Mechanism of Iridium (III) -Catalyzed Oxidation of Ethanol Amine by Cerium (IV) in Sulfuric Acid Media

Abstract

In this study, the kinetics and mechanism of the iridium (III)-catalyzed oxidation of ethanol amine (EAN) by cerium (IV) in a sulfuric acid medium was investigated using titrimetric technique of redox in a temperature range of 298—313 K. It was found that the reaction is of first order with respect to Ce(IV) and Ir(III), and a positive fractional order with respect to EAN. It was also found that the pseudo-first-order ([EAN]>> [Ce(IV)]) rate constant k obs decreases with the increase of [H + ] and [HSO − 4 ]. Under the protection of nitrogen gas, the reaction system can initiate the polymerization of acrylonitrile, indicating the generation of free radicals. On the basis of the experimental results, a suitable mechanism was proposed. From the dependence of k obs On the concentration of hydrogen sulfate, Ce(SO 4 ) 2 was found to be the kinetically active species. The rate constants of the rate-determining step together with the activation parameters were evaluated.