KINETICS AND MECHANISM OF H2O2 DECOMPOSITION BY CU(II)-AMINE CO(II)-AMINE AND FE(III)-AMINE COMPLEXES ON THE SURFACE OF SILICA-ALUMINA (25-PERCENT AL2O3)

The kinetics of the H2O2 decomposition by Cu(II)-, Co(II)-, and Fe(III )-amine complexes supported on the surface of silica-alumina (25% Al2O 3) catalyst have been investigated. The decomposition process proceede d with first-order kinetics for the substrate concentration. With copp er complexes, in particular, the rate of reaction decreased in the seq uence: ethylenediamine (en) > monoethanolamine (mea) > triethanolamine (tea). With ethylenediamine as aligand, the rate has also decreased i n the order: Cu(II) > Co(II) > Fe(III). Both of the energy and entropy of activation were found to decrease as: en > mea > tea and for one l igand (en) and different metal ions the sequence was Cu(II) > Co(II) > Fe(III). The decomposition reaction involved the formation of an inte rmediate active species, which converts into a peroxo-metal-complex of brown or faint red color. The rate of reaction was directly proportio nal to the [complex], [H2O2], and [H]-1. A mechanism describing the de composition process is proposed. (C) 1994 John Wiley & Sons, Inc.