Cobalt migration inside a mordenite framework upon CO chemisorption and CO oxidation

Abstract

A Co mordenite (CoM) has been investigated to determine its suitability as a catalyst for the oxidation of CO. It proved to be an active catalyst for this reaction. After treatment at 773 K in CO followed by O₂ at the same temperature, the reaction rate increased by three orders of magnitude. This treatment also enhanced the CO adsorption capacity of the solid. Two different rate laws were found. The fresh sample was fractional order in O₂ and CO, 0.5 and 0.75, respectively, with an activation energy of 87.9 kJ mol^–1. After treatment, the rate was zero order in CO and first order in O₂ and the activation energy was 48.9 kJ mol^–1. The enthalpy of adsorption was also different for fresh and treated CoM, 39.7 and 48.1 kJ mol^–1, respectively. The results obtained are analysed in terms of the mobility of the cations from hidden to accessible sites in the mordenite framework, where different active sites may be generated.