Heterogeneous catalytic systems Dissipative structures

ON THE THEORY OF THE ORIGIN OF SPATIALLY NONUNIFORM STATIONARY STATES (DISSIPATIVE STRUCTURES) IN HETEROGENEOUS CATALYTIC SYSTEMS... 

On The Theory Of The Origin Of Spatially Nonuniform Stationary States (Dissipative Structures) In Heterogeneous Catalytic Systems 551... 

In real systems, especially in heterogeneous catalytic and biological sys terns, the reactants are often arranged irregularly in space. Therefore, an arising instability may cause simultaneous diffusion of substances from one point to another inside the system to make the reactant concentration oscillations arranged in a certain manner in space during the occurrence of nonlinear chemical transformations. As a result, a new dissipative structure arises with a spatially nonuniform distribution of certain reac tants. This is a consequence of the interaction between the process of diffusion, which tends to create uniformity of the system composition, and local processes of the concentration variations in the course of nonlinear... 

Rate oscillations, spatiotemporal patterns and chaos, e.g. dissipative structures were also observed in heterogeneous catalytic reactions. If compared with pattern formation in homogeneous systems, the surface studies introduced new aspects, like anisotropic diffusion, and the possibility of global synchronization via the gas phase. Application of field electron and field ion microscopy to the study of oscillatory surface reactions provided the capability of obtaining images with near-atomic resolution. The most extensively studied reaction is CO oxidation, which is catalyzed by group VIII noble metals. 

This ratio is vahd when the system operates close to thermodynamic equihbrium. It is, however, typical for heterogeneous catalysis to occur far from equihbrium in an open, nonlinear, dissipative, distributed, and multiparametric medium. Thus heterogeneous catalytic reactions exhibit diverse nonlinear phenomena the multiplicity of steady states (stable and unstable) hysteresis phenomena the ignition and extinction of the process critical phenomena phase transitions a high sensitivity of the process to changes in the parameters oscillations and wave phenomena chaotic regimes the formation of dissipative structures and seh organization phenomena. 

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