Definition of Conversion

In defining conversion, we choose one of the reactants as the basis of caicuia-tion and then relate the other species involved in the reaction to this basis. In virtually all instances it is best to choose the limiting reactant as the basis of calculation. We develop the stoichiometric relationships and design equations by considering the general reaction 

The uppercase letters represent chemical species and the lowercase letters represent stoichiometric coefficients. Taking species A as our basis of calculation, we divide the reaction expression through by the stoichiometric coefficient of species A. in order to arrange the reaction expression in the form 

Now we ask such questions as How can we quantify how far a reaction [e.g.. Equation (2-2)] proceeds to the right or How many moles of C are formed for every mole A consumed A convenient way to answer these questions is to define a parameter called conversion. The convension is the number of moles of A that have reacted per mole of A fed to the system  

Because we are defining conrersion with respect to our basis of calculation [A in Equation (2-2)]. we eliminate the subscript A for the sake of brevity and lei X s.  

For irre ersible reactions, the maximum conversion is 1.0. i.e., complete conversion. For reversible reactions, the maximum conversion is the equilibrium conversion (i.e., X.  

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Equation (4.10) uses the general definition of fraction unreacted in a flow system. It is moles out divided by moles in. The corresponding, general definition of conversion is... 

Two concepts are often used to describe the behaviour of a process involving reactions conversion and selectivity. Conversion is defined with respect to a particular reactant, and it describes the extent of the reaction that takes place relative to the amount that could take place. If we consider the limiting reactant, the reactant that would be consumed first, based on the stoichiometry of the reaction, the definition of conversion is straight forward ... 

The selectivity and yield of hydrogen, acetylene, and carbon monoxide can be seen in Figures 3-5. The definitions of conversion, selectivity, and yield for this system are as follows ... 

Hie chemical reaction rate is usually dependent on the molar concentrations of the reactants and not on their mass fractions, because it depends on the chance of collision of molecules. However, here the definition of in terms of mass fractions is preferred, because it can readily be incorporated into mass balances. A definition in terms of moles or molar concentrations might invite the use of mole balances instead of mass balances. Since, contrary to conservation of mass, there is no such thing as conservation of moles (because one molecule might divide into several molecules, or several might condense into one), the use of mole balances is strongly dissuaded. More information concerning the definition of conversion can be found elsewhere [2]. 

In FCC, the conversion is usually defined as the yield in gasoline, LPG and ftielgas, but in this study, the conversion of an experiment is defined as the amount of heavy cycle oil (HCO) converted. This was done because the feed consists only of HCO and thus LCO would be a product. The conclusions drawn in this paper are not affected by this definition of conversion. 

To determine the reactor length L necessary to achieve a conversion X, we combine the definition of conversion. 

To an applied chemist or an engineer, one further piece of information related to the performance of a reaction is needed to estimate the quantitative results of a process, and that is the conversion. A good working definition of conversion is given by Eq. 1.10. 

Definition of conversion in batch and flow reactors and its relation to the extent of a chemical reaction... 

From the definition of conversion, we substitute not only for the molar flow rate of SO (A) in terms of conversion but also for the volumetric flow rate as a function of conversion. 

Equation (1-47) is one of the few that should be committed to memory immediately. There are, of course, corresponding definitions of conversion on the basis of mass units, and in some cases fractional conversion to product (mols product made per mol reactant fed or reacted) is a useful measure. The important thing is always to be sure how the term conversion is defined. The integrated forms of simple irreversible rate laws written with conversion, x, from equation (1-47) are ... 

Note that the extent of reaction in percent is 100a. See also Eq. (3.3) in Section 3.5 for the general definition of conversion a in a TGA experiment. 

Conversion. For the expression of activity, another visual index is conversion. The properties of catalysts are often measured by this parameter for industrial purposes. The definition of conversion is ... 

Two of the more common conversion and conversion-related terms will now be discussed in this section. The symbol N is used to represent the number of moles of a species at time t at initial conditions t = 0), a subscript, o, can be included with N. In line with the definition of conversion the symbol a is employed to represent the... 

Various definitions of conversion are employed in reactor calculations. Much of this material was presented in Chapter 5 in Part I, but is repeated here for the convenience of the reader. Equations (8.4) and (8.5) are now rewritten in terms of new variables. Since... 

On the other hand, I do not wish to develop monolithic definitions of conversion in the second century. For one, it is difficult to infer from our limited range of sources what people of antiquity might have felt about the cosmos. To posit such a theory I would open myself to the same criticism which I leveled at scholars such as Cumont and Nock, who applied psychological principles to late antique religious texts. I can conclude only that the rhetoric of enslavement to fate occurs within a limited number of sources in antiquity, all of which derive (to the best of our knowledge) from the Roman Empire in the second century. 

The original definition of conversion was based on estimates of the amounts of C3AHg and CAHj this was subject to significant error due to the carbonation of C3AHg.l l Further, Eq. (3) for degree of conversion, Z), described above (K = 1) is modified to account for instrument effects by an empirical constant, I, determined by the use of calibration standards. Bushnell-Watson and Sharp note that A itself may vary with the degree of conversion.lfi... 

In Chapter 2, we combined the different reactor mole balances with the definition of conversion to arrive at ihe design equation for each of four types of reactors, as shown in Table 3-2. Next we showed that if the rate of disappearance is known as a function of the conversion Jf ... 

It is often more convenient to work in terms of monomer conversion X. By making use of the definition of conversion ... 

Ignoring a permanent competition of intra- and intermolecular condensation steps causes problems for the interpretation of Rory s formulas regardless, if KC or TC polycondensations are concerned. These problems begin with the definition of conversion, p, (Eq. 4.1), because a quantitative conversion (p = 1) cannot be achieved in a perfectly linear polycondensation. For the end of a linear polycondensation a DFmax may be defined which equals the niunber of monomers initially present in the reaction mixture and thus, also equals the number of a groups regardless, if a—b or 02 + monomers are polymerized (Eq. 4.44). 

Based on the definition of conversion given in Eq. (8.1), (or Eq. 4.1), and according to the correlation between DPn and conversion p (Eq. 8.2), a polycondensation should yield the highest molar mass, when ... 

Regardless of the scenario it must be kept in mind that a ROP plus polycondensation process needs two different definitions of conversion for its proper description. For the ROP part the conversion is defined by the consumption of monomers as usual for a chain-growth polymerization. Yet, for polycondensations the conversion is defined by the consumption of functional (end) groups regardless, if inter- or intramolecular condensation steps take place. 

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