Effect of Parameters and Operating Conditions

The oscillations observed with but-l-ene at 150°C are made up of two different portions. One is of sinusoidal type and the other consists of relaxation jumps between low and high conversion states. The parameters, k and A 4, adsorption and desorption rate constants of but-l-ene on the platinum surface, ks the surface reaction rate constant between O2 and but-l-ene, Zq the capacity factor, change the characteristics of these oscillations. Operating conditions like reactor temperature, flow rate, volume, mass of catalyst and concentration of but-l-ene in the feed also affect these oscillations both experimentally and in computer simulations. 

The smaller oscillations observed at the high conversion state have a time period of 1.5-2 min, which is also confirmed from the experimental transient. Very slow desorption of but-l-ene from the Pt surface stretches the time period of oscillation to values of the order of 30 min. 

A large amount of theoretical and experimental work has been reported in the literature on oscillatory oxidation reactions over noble metal catalysts. Several models have been proposed to account qualitatively for these 

For a simple elementary step model for CO oxidation to produce theoretical sinusoidal oscillations, the feed has to contain a stoicheiometric excess of the gas which is being oxidized however the addition of an inert buffer step allows the system to exhibit oscillations even with excess O2. 

The addition of a third species can lead to a wide range of relaxation and multi-peak oscillations. The model described in the text which takes into account the interaction of all three gases indicated that a wide range of multiple peak and sinusoidal oscillations are possible. 

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