Instantaneous selectivity parallel reactions

The following details mathematical expressions for instantaneous (point or local) or overall (integral) selectivity in series and parallel reactions at constant density and isotliermal conditions. An instantaneous selectivity is defined as the ratio of the rate of formation of one product relative to the rate of formation of another product at any point in the system. The overall selectivity is the ratio of the amount of one product formed to the amount of some other product formed in the same period of time. 

The E-model was also applied to a system of parallel reactions (Baldyga and Bourne, 1990a). It was found that selectivity depends on compositions of both the initial reactor content and the stream added for chemically equivalent mixtures of three reactants (see reaction system given by Eqns. (5.4-143) and (5.4-144)). For an instantaneous reaction, the yield of 5 varies from 0 to 100 % depending on the mode of composing the feeding stream. 

Here SB,c is the instantaneous selectivity of the desired product B to unwanted product in this parallel reaction. 

Consider the instantaneous selectivity for the two parallel reactions just discussed ... 

Straight forward problem to reinforce principles of how to choose reactor schemes to maximize the instantaneous selectivity for parallel reactions. 

This gives a formula for the instantaneous selectivities of parallel reactions in terms of known and measured quantities. From this we can calculate e at each instant of the TSR experiment. We can develop these formulas further in order to get a direct formula for s. Since... 

The overall or global selectivity over the time span 0-f during which the reacting species were in contact is obtained after integration. It is generally different from the instantaneous value, but in the particular case of parallel reactions with the same order the two are identical ... 

Coke oven gas consists mainly of a mixture of carbon monoxide, hydrogen, methane, and carbon dioxide. It is contaminated with a variety of organic and inorganic compounds that have to be separated in absorption columns before its further use as a synthesis gas. The selective absorption of coke plant gas contamination results from a complex system of parallel liquid-phase reactions. Instantaneous reversible reactions ... 

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See also in sourсe #XX -- [ , ]

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