Batch Stoichiometric Table SpeciesSymbolInitialChangeRemaining DD ________ ____________ CC B B A A InertI where and

Concentration: Batch Systems Constant Volume Batch: Note: if the reaction occurs in the liquid phase or if a gas phase reaction occurs in a rigid (e.g., steel) batch reactor Then etc. If then And we have –r A =f(X)

Flow System Stoichiometric Table SpeciesSymbolInitialChangeRemaining ________ ____________ A B B A CC DD InertI where and

Concentration: Liquid Flow System Flow Stystem: Liquid Phase Flow System: etc. If the rate of reaction were then we would have This gives us -r A = f(X). Consequently, we can use the methods discussed in Chapter 2 to size a large number of reactors, either alone or in series.

Concentration: Gas Flow System with THEN Note that the reaction is: A + (b/a)B -  (c/a)C + (d/a)D THEN IF the reaction rate is given by -r A = k C A 2 CB

Multiple Reactions Use molar flow rates and concentrations; DO NOT use conversion! Types of Multiple Reactions 1.Series Reactions 2.Parallel Reactions 3.Complex Reactions: Series and Parallel 4.Independent

Selectivity and Yield InstantaneousOverall Selectivity Yield: Example:(1)desired product, r D =k 1 C A 2 C B (2) undesired product, r U =k 2 C A C B

Another example about Selectivity and Yield (1)desired product, r D =k 1 C A 2 C B (2)undesired product, r U =k 2 C A C B (3) then CACA S D/U1/U2

Algorithm for Multiple Reactions

Mole Balances

Net Rate of Reaction for Species A

Series Reactions, t=0 C A =C A0

Series Reactions

Elementary Multiple Reactions

Case 1:Liquid Phase Reaction in a CSTR

Polymath Solution

Elementary Multiple Reactions

Example: Liquid Phase Reaction

Multiple Reactions — Gas Phase Use Molar Flow Rates!!!

The Algorithm

(given)

The Algorithm

Heterogeneous Catalytic Reaction 1-External diffusion of reactants towards the external surface of the catalyst pellet 2-Internal diffusion of reactants into the pores of the catalyst pellet 3- Adsorption of reactants on the active sites 4- Surface reaction 5- Desorption of products from active sites into the pore volume of the catalyst pellet 6- Internal diffusion of products through the pores of the catalyst pellet towards the external surface of the catalyst pellet 7- External diffusion of products to the bulk of the fluid

Molecular Adsorption

Steps of Catalytic Reaction B B

B B B D A A B C C D A B C + D C D + C + D

Example: Catalytic Reaction to Improve the Octane Number of Gasoline Focusing on the second reaction:

Example: Catalytic Reaction to Improve the Octane Number of Gasoline

Different Surface Mechanisms