Studying the Stage of Nitric Oxide Desorption from the Surfaces of CuO/γ-Al2O3 Catalysts, with or without a Reducing Agent

Abstract

Nitric oxide desorption from the surfaces of supported copper-containing catalysts (CuO/γ-Al2O3) as a function of temperature is studied. NO preadsorption occurs both in an inert medium of argon and in the presence of oxygen. It is shown that the presence of oxygen considerably raises the capacity of the samples with respect to NO, due to the activation of a supplementary redox mechanism. In addition, the maximum desorption temperature shifts to the region of higher temperatures. For a sample exhibiting the highest capacity with respect to NO, the desorption process is conducted using hydrogen and propane as reducing agents. Desorption with hydrogen leads to the reduction of adsorbed species at temperatures of 160–190°C. With propane, NOx desorption proceeds mostly due to the thermal degradation of adsorbed nitrogen species to NO in the temperature range of 180–250°C, as in an inert atmosphere. The contribution from reduction due to the presence of propane manifests at temperatures of 260–300°C.