Boreskov Institute of Catalysis of the Siberian Branch of Russian ...

OP-I-8KINETICS OF CARBON MONOXIDE OXIDATION OVER CuO/CeO 2CATALYSTSJ.L. Ayastuy, A. Gurbani, M.P. González-Marcos, M.A. Gutiérrez-OrtizDept. of Chemical Engineering, Faculty of Science and Technology, University of the BasqueCountry. P.O.Box 644, 48940-E, Bilbao, SpainFax: 0034-946013500, e-mail: joseluis.ayastuy@ehu.esIntroductionCeria supported CuO catalyst have been reported as very active in low temperature COoxidation catalyst [1,2] due to its high capacity to storage and supply oxygen [3] the COoxidation is believed to follow Mars-Van Krevelen (MVK) mechanism, but also Langmuir-Hinshelwood (LH) mechanism is reported in literature [4]. In this work the kinetics of pureCO oxidation over CuO/ceria catalysts has been investigated and the experimental data werefit with several mechanistic models.ExperimentalCuO/CeO 2 catalyst was prepared by wet impregnation with CuO loading of 7% in weight(being real value 6.9), dried and calcined in air at 400°C for 5 h. Previous to kineticexperiments, catalyst was reduced in hydrogen stream at 300°C for 1 h. The catalyst wascharacterized by BET, XRD, H 2 -TPR, CO-TPD, O 2 -TPD and oxidation-reduction cycles.Kinetic experiments were carried out in differential regime, with gas total flow rate of200 cm 3 /min and for several feed stream composition, being the catalyst particles size of 0.16-0.25 mm. The experiments were carried out at four temperatures (in the range 300 to 353 K)and the obtained 61 experimental data were fit to power law rate and several mechanistic rateequations (LH and MVK).Genetic algorithm (GA) was used to optimization of rate equations parameters, byminimizing the objective functionN∑ ( rexp− rcalc)i = 1. The initial population of 100 individuals,mutation fraction of 0.1 and 200 generations were found as optimal values for running the GA.ResultsThe OSC capacity of the catalyst measured at 120°Cby CO-He-O 2 steps (Figure 1) reveals that after oxygenstep followed by helium step, CO 2 is produced afterswitching to CO, being supplied the necessary oxygenby ceria lattice (calculated to be 0.18 mmol O 2 /g). Thisagrees with CO-TPD (not shown), in which thepreadsorbed CO is removed in form of CO 2 , with Figu re 1. CO, CO 2 and O 2 evolution during5%O 2 →He→5%CO steps at 120ºC.240