Propane partial pressure influence

The C3Hg conversion is never complete. However the maximum in NO conversion observed when the oxygen content increases is not due to a deactivation of the catalyst because additional runs with low oxygen contents lead to NO conversion similar to those of the first run. The decrease may be due to the influence of the propane partial pressure. 

In general, with decreasing hydrocarbon partial pressure, unsaturated components such as acetylene, ethylene, propylene, and butadiene increase whereas BTX, pyrolysis fuel oil, and saturated components such as methane, ethane, and propane decrease. Low hydrocarbon partial pressure can be attained either by high steam dilution or by low absolute pressure in the cracking coil, which is determined by furnace outlet pressure and pressure drop in the cracking coil. For each specific case there is an optimum steam dilution. Reduction of steam dilution influences yields, utilities, running times and, in the case of a new ethylene plant, of course, investment costs—but in different ways, either positive or negative. Thus, an optimization has to be carried out to identify the most economic steam dilution. 

Equation (2) explains the transient deactivation with a model describing reversible and irreversible coke. We can see that the partial pressure of propane in the reactor does not influence the deactivation. This has also been demonstrated in an earlier study of the same system [8]. This observation is consistent with kinetic models for propane dehydrogenation proposed by Loc et al. [13]. They suggested that the rate-determining step is the dissociative adsorption of propane. From this mechanism it follows that the deactivation will be... 

The influence of antimony content and of ammonia partial pressure on the selectivity of the (amm)oxidation of propene and propane with FeSb04 can be understood in terms of the degree of reduction of the catalyst surface at steady state conditions. The higher the degree of reduction which can be caused either by a low antimony content or by a high ammonia partial pressure the higher the selectivity for the combustion/degradation products. 

The influence of partial pressures of propane and oxygen was studied at 550°C have been correlated using the well known Mars and van Krevelen [9] mechanism... 

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