Transient analysis of oxygen storage capacity of Pt/CeO2–ZrO2 materials with millisecond- and second-time resolution

A simple method for determining the speed of oxygen release from Pt/CeO2–ZrO2 materials is proposed. We determined the speed of oxygen release from three differently prepared Pt(1 wt%)/CeO–ZrO2 catalysts by two methods: the method employing temporal analysis of products (TAP) reactor with CO, O2, and CO2 pulsed gases, and a conventional method with CO and O2 switch gases. Strong CO2 adsorption precluded correct analysis of oxygen release speed, when it was determined from the amount of CO2 formed. Therefore, instead of the amount of CO2 formed, we suggested the tmax value, defined as the position of maximal intensity of CO2 transient responses obtained upon low-intensity (1015–1016 molecules) CO pulsing in the TAP reactor. Shorter the tmax value, higher the rate of oxygen release, because the temperature dependence of the tmax determined in the present study resembles the previous results of oxygen release analysis [T. Tanabe, A. Suda, C. Descorme, D. Duprez, H. Shinjoh, M. Sugiura, Stud. Surf. Sci. Catal. 138 (2001) 135].