i zyxwv APPLICATION OF COMPUTER MODELING TECHNIQUES TO THE KINETICS OF THE REACTION OF CARBON WITH OXYGEN S. Ahmed and M.H. Back Ottawa-Carleton Chemistry Institute, University of Ottawa Campus, Ottawa, Canada K1N 6N5 and J.M. Roscoe Department of Chemistry, Acadia University, Wolfville, Nova Scotia BOP zyx 1x0 ABSTRACT Computer modeling techniques are applied to the kinetics of the reaction of carbon with oxygen. The rates of disappearance of oxygen, of formation of CO, C02 and the surface complex, measured over the temperature range 748-1173 K and the pressure range 0.5-400Pa may be described by a mechanism involving adsorption of oxygen, formation of the strongly-bound complex, desorption of the complexand reaction of the complex with a gas-phase molecule of oxygen. The latter is shown to be an important source of C02 at lowtemperatures and higher pressures of oxygen. An important featureof the mechanism is the existence of at least two distinct types ofactive sites for the binding of the complex on the carbon surface,each with a characteristic reactivity. Most of the results on whichthe model is based were obtained using thin films of pyrolyticcarbon, but some results from the oxidation ofgraphon are alsoconsistent with the mechanism. INTRODUCTION The purpose of the present study is to illustrate the application of computer modeling techniques to the reaction of carbon with oxygen. The kinetics of this reaction have been studied over a period of several decades (1,2) with most emphasis placed on steady-state solutions leading to an interpretation of the order and activation energy of the over-all rate. The importance of the strongly-bound surface complex in the oxidation process was first recognized by Walker and colleagues (3). The properties of the complex have been extensively studied (4,5,6) but its role in the various elementary surface processes involved in oxidation is not understood in detail. The development of computer modeling techniques has opened the way for the testing and evaluation of mechanisms with far more sensitivity than is possible with steady-state methods. requirement in the use of these techniques is the availability of reliable measurements for the rates of the elementary processes in the mechanism. Recently, kinetic studies of the reaction of oxygenwith carbon in a static system (7), involving a complete analysis ofthe time course of the reaction in terms of the depletion of oxygenand carbon and of the formation of carbon monoxide and carbondioxide, led to an estimate of the concentration of adsorbed specieson the surface and of the values A major zy 63