Heterogeneous Chain Termination. Diffusion and Kinetic Regions

2 Heterogeneous Chain Termination. Diffusion and Kinetic Regions 

Besides chain termination in the gas phase, the termination on the reactor wall, which becomes dominant at low pressures, must also be considered. 

Usually, the rate of heterogeneous chain termination is first order with respect to active centers 

Equating (for a stationary process) the rate of the surface reaction of active centers to that of their diffusional flow, i.e. to q, we find w = kn = p(n — n ), whence 

Consider two limiting cases derived from the general expression (37.4). 

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