The Decomposition of Perchloric Acid on Metal Oxide Catalysts

The thermal decomposition of perchloric acid has been investigated on five Harshaw catalysts: copper chromite, alumina, iron(III) oxide, copper(II) oxide, and manganese(IV) oxide (the last three being supported on alumina). Manganese(IV) oxide gave complex kinetics which were not fully analyzed but on the other four catalysts the reaction was.first order. Activation energies were: copper chromite, 54 kcal/mol; alumina, 28.8 kcal/mol; iron(III) oxide, 28.6 kcal/mol; copper(II) oxide, 39.0 kcal/mol. A mechanism is proposed for the decomposition which involves proton transfer to an accepter (typically an O2− ion) in the catalyst surface followed by decomposition of the ClO4− anion formed in this process. Some observations on the catalyzed thermal decomposition of ammonium perchlorate are presented.