Parallel Reactions

The net rate of disappearance of A

Instantaneous selectivity

If α > β use high concentration of A. Use PFR.
If α < β use low concentration of A. Use CSTR.

Series Reactions (p. 283)

Example: Series Reaction in a batch reactor

This series reaction could also be written as         

Reaction (1) : -r1A=k1CA

Reaction (2): -r2B=k2CB

Mole Balance on every species

Species A:Combined mole balance and rate law for a control volume batch reactor.
Net Rate of Reaction of A
	rA=r1A+0
Rate Law
	r1A=-k1ACA
Relative Rates
	r1B=-r1A
Integrating with CA=CA0 at t=0 and then rearranging
Mole Balance
Species B:
Net Rate of Reaction of B
Rate Law
	r2B=-k2CB
Relative Rates
Combine
Using the integrating factor, i.f.:
Evaluate
at t = 0, CB = 0
When should you stop the reaction to obtain the maximum amount of B? Let’s see.
Optimization of the Desired Product B
Then
Species C	CC = CA0 – CB – CA
And

 Finding the Selectivity

 in a CSTR

Concentration-Time Trajectories

Schemes for maximizing the selectivity for Van Der Vusse Kinetics