CO Oxidation Reaction by Platinum Clusters on the Surface of Multiwalled Carbon Nanotubes: Experimental and Theoretical Study of Kinetics in a Wide Range of O2/CO Ratios

This work presents a systematic study of the kinetic aspects of CO oxidation reaction catalyzed by platinum nanoparticles (NPs) supported on the surface of multiwalled carbon nanotubes (MWCNTs). The investigation presented is closely related to the actual practical task of air purification in enclosed spaces. Therefore, the catalytic reaction was carried out in the presence of an excess of oxygen (5 vol.%) and over a wide range of CO concentrations from 50 ppm to 1600 ppm. For the catalyst characterization, transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) were applied. Kinetic modelling based on the Langmuir-Hinshelwood and Mars-van Krevelen mechanisms was taken as a basis, using the results obtained on Pt foil. Simulation of CO oxidation reaction on platinum NPs at temperatures above 90 degrees C was carried out using a kinetic model describing the reaction mechanism on bulk platinum. The description of the kinetics of CO oxidation reaction on Pt NPs over the entire temperature range, including the low temperatures down to -40 degrees C, required the introduction of the steps characterizing an additional concerted mechanism related to CO-assisted O-2 dissociation. Using the presented model, some predictions of the kinetic behaviour of the system were made.