Effect of the Nature of the Precursor on the Activity of Copper-Containing Catalysts Based on Erionite in Oxidation of CO

We have studied the catalytic activity of copper-containing zeolite catalysts based on erionite (ERI) in oxidation of CO. We have established that the activity of Cu-ERI systems is due to isolated coordination unsaturated Cu2+ cations which are stabilized in the catalyst on sites with strong tetragonal distortion and are reduced to Cu+ during catalysis. According to X-ray photoelectron spectroscopy (XPS), diffuse reflection electronic spectra, and temperature programmed reduction by hydrogen (TPR-H2) spectra, activity differences between 3% Cu-ERI catalysts obtained from different precursors are determined by the different numbers of Cu2+ cations capable of being reduced during the reaction at T < 400 °C: the higher the content of such cations in the samples, the higher the activity of the Cu-ERI systems.