Analysis of heterogeneous–homogeneous model, describing oscillations in system CH3CHO+O2 Original Research Article

The heterogeneous–homogeneous model of acetaldehyde oxidation involving surface processes and feedback (inhibition) has been considered. The leading active centres of chain process, peroxy radicals (RCO3), produce an inhibitor — highly vibrationally excited molecules of formaldehyde (CH2O(v)) on the surface of the reaction vessel and react with them in the volume. On the example of CH3CHO, it is shown that at low-temperature oxidation of organic compounds the appearance of concentration oscillations is possible. The trajectories and bifurcation changes of the reaction by the variation of parameters have been investigated. The influence of number of surface active centres, of rates of inhibitors quenching, the adsorption and heterogeneous recombination of radicals on the reaction dynamic have been studied. The parametrical analysis has shown that the slow quenching of excited formaldehyde and rather fast transfer of its internal energy to leading radicals result in autooscillations. The increase of the quenching rate brings to the oscillations damping. The latter is observed also with the reduction of the ratio of rate constants of radicals adsorption to their surface reaction. It is shown that the quenching rate influences the number of pulses.