Selfoscillation damping of the $\mathrm{NO}+\mathrm{CO}$ reaction on $\mathrm{Pt}$ catalyst, caused by surface defects

G. G. Yelenin ; A. G. Makeev

Matematičeskoe modelirovanie, Tome 8 (1996) no. 12, pp. 62-76.

Résumé

The paper is devoted to mathematical modelling of the selfoscillatory and autowave regimes in the $(\mathrm{NO}+\mathrm{CO})/\mathrm{Pt}(100)$ reaction at relatively low partial pressures in gaseous phase ($P_{\mathrm{NO}},P_{\mathrm{CO}}\cong10^{-6}$ mbar). Both one- and two-dimensional mathematical models of the nonideal pactional system are based on partial differential equations of reaction-diffusion type. Surface defects are shown to cause the experimentally observed damping of selfoscillation of the surface-average reaction rate. The greater rate of $\mathrm{NO }$ dissociation at the defects leads tothe appearance of autowaves, spreading from defects along the oscillating background. Replacement of the spatially-uniform oscillatory regime by the new autowawe state causes the dampingof the surface-average reaction rate. At the same time, the mean value of the reaction rate over the region, smaller than the wave length, varies periodically in time. It was found out, that the dependence of the damping time of selfoscillation on the activation energy of $\mathrm{NO}$ dissociation at defects is not monotonous. The observed nonequilibrious transfer "selfoscillations $\Rightarrow$ autowaves" differs from the transfer "selfoscillations $\Rightarrow$ Turing dissipative structures", studied before, which also causes the damping of selfoscillations of the reaction rate.