Silica-supported binuclear copper oxide catalysts derived from cupric acetate monohydrate. Their spectroscopic characterization and catalytic nature in carbon monoxide isotope equilibriation or carbon monoxide oxidation with nitrous oxide

Abstract

Novel silica-supported copper oxide catalysts have been prepared by impregnating silica with an aqueous solution of cupric acetate monohydrate, a typical binuclear copper complex. Binuclear copper(II) ions, mononuclear copper(II) ions and highly dispersed cupric oxide on the calcined samples have been characterized using e.s.r. and/or i.r. spectroscopy using acetic acid as a probe. Significant amounts of binuclear copper(II) ions were estimated on silica from the spin concentration of the e.s.r. signal. The rate of CO isotope equilibriation or CO oxidation with N₂O is a function of the number of binuclear copper ions, indicating that this binuclear structure is responsible for both reactions. The importance of the hydroxyl group in anchoring the cupric acetate complex on silica is stressed, and a reaction mechanism for the oxidation of CO with N₂O has been suggested on the basis of the binuclear structure of the copper ions.