1. Chemical Reaction Engineering
Chapter 1:
General Mole Balance Equation Applied to
Batch Reactors, CSTRs, PFRs, and PBRs

2. Chemical Identity
A chemical species is said to have reacted when it has lost its chemical identity.

3. Chemical Identity
A chemical species is said to have reacted when it has lost its chemical identity.
The identity of a chemical species is determined by the kind, number, and configuration of that species’ atoms.

4. Chemical Identity
A chemical species is said to have reacted when it has lost its chemical identity.
The identity of a chemical species is determined by the kind, number, and configuration of that species’ atoms.
1. Decomposition

5. Chemical Identity
A chemical species is said to have reacted when it has lost its chemical identity.
The identity of a chemical species is determined by the kind, number, and configuration of that species’ atoms.
1. Decomposition
2. Combination

6. Chemical Identity
A chemical species is said to have reacted when it has lost its chemical identity.
The identity of a chemical species is determined by the kind, number, and configuration of that species’ atoms.
1. Decomposition
2. Combination
3. Isomerization

7. Reaction Rate
The reaction rate is the rate at which a species looses its chemical identity per unit volume.

8. Reaction Rate
The reaction rate is the rate at which a species looses its chemical identity per unit volume.
The rate of a reaction can be expressed as the rate of disappearance of a reactant or as the rate of appearance of a product.

9. Reaction Rate
The reaction rate is the rate at which a species looses its chemical identity per unit volume.
The rate of a reaction can be expressed as the rate of disappearance of a reactant or as the rate of appearance of a product.
Consider species A:

10. Reaction Rate
The reaction rate is the rate at which a species looses its chemical identity per unit volume.
The rate of a reaction can be expressed as the rate of disappearance of a reactant or as the rate of appearance of a product.
Consider species A:
rA = the rate of formation of species A per unit volume

11. Reaction Rate
The reaction rate is the rate at which a species looses its chemical identity per unit volume.
The rate of a reaction can be expressed as the rate of disappearance of a reactant or as the rate of appearance of a product.
Consider species A:
rA = the rate of formation of species A per unit volume
-rA = the rate of a disappearance of species A per unit volume

12. Reaction Rate
The reaction rate is the rate at which a species looses its chemical identity per unit volume.
The rate of a reaction can be expressed as the rate of disappearance of a reactant or as the rate of appearance of a product.
Consider species A:
rA = the rate of formation of species A per unit volume
-rA = the rate of a disappearance of species A per unit volume
rB = the rate of formation of species B per unit volume

13. Reaction Rate EXAMPLE:
If B is being formed at 0.2 moles per decimeter cubed per second, ie,
rB = 0.2 mole/dm3/s

14. Reaction Rate EXAMPLE:
If B is being formed at 0.2 moles per decimeter cubed per second, ie,
rB = 0.2 mole/dm3/s
Then A is disappearing at the same rate:
-rA= 0.2 mole/dm3/s

15. Reaction Rate EXAMPLE:
If B is being formed at 0.2 moles per decimeter cubed per second, ie,
rB = 0.2 mole/dm3/s
Then A is disappearing at the same rate:
-rA= 0.2 mole/dm3/s
The rate of formation (generation of A) is
rA= -0.2 mole/dm3/s

16. Reaction Rate
For a catalytic reaction, we refer to -rA', which is the rate of disappearance of species A on a per mass of catalyst basis.

17. NOTE: dCA/dt is not the rate of reaction
Reaction Rate
For a catalytic reaction, we refer to -rA', which is the rate of disappearance of species A on a per mass of catalyst basis.
NOTE: dCA/dt is not the rate of reaction

18. Reaction Rate
Consider species j:

19. Reaction Rate Consider species j:
rj is the rate of formation of species j per unit volume [e.g. mol/dm3*s]

20. Reaction Rate Consider species j:
rj is the rate of formation of species j per unit volume [e.g. mol/dm3*s]
rj is a function of concentration, temperature, pressure, and the type of catalyst (if any)

21. Reaction Rate Consider species j:
rj is the rate of formation of species j per unit volume [e.g. mol/dm3*s]
rj is a function of concentration, temperature, pressure, and the type of catalyst (if any)
rj is independent of the type of reaction system (batch, plug flow, etc.)

22. Reaction Rate Consider species j:
rj is the rate of formation of species j per unit volume [e.g. mol/dm3*s]
rj is a function of concentration, temperature, pressure, and the type of catalyst (if any)
rj is independent of the type of reaction system (batch, plug flow, etc.)
rj is an algebraic equation, not a differential equation

23. Reaction Rate Consider species j:
rj is the rate of formation of species j per unit volume [e.g. mol/dm3*s]
rj is a function of concentration, temperature, pressure, and the type of catalyst (if any)
rj is independent of the type of reaction system (batch, plug flow, etc.)
rj is an algebraic equation, not a differential equation
We use an algebraic equation to relate the rate of reaction, -rA, to the concentration of reacting species and to the temperature at which the reaction occurs [e.g. -rA = k(T)CA2].

24. General Mole Balance

25. General Mole Balance

26. Batch Reactor Mole Balance

27. Batch Reactor Mole Balance

28. Batch Reactor Mole Balance

29. Batch Reactor Mole Balance

30. Constantly Stirred Tank Reactor Mole Balance

31. Constantly Stirred Tank Reactor Mole Balance

32. Constantly Stirred Tank Reactor Mole Balance

33. Constantly Stirred Tank Reactor Mole Balance

34. Constantly Stirred Tank Reactor Mole Balance

35. Plug Flow Reactor Mole Balance
PFR:

36. Plug Flow Reactor Mole Balance
PFR:

37. Plug Flow Reactor Mole Balance
PFR:

38. Plug Flow Reactor Mole Balance
PFR:

39. Plug Flow Reactor Mole Balance
PFR:

40. Plug Flow Reactor Mole Balance
PFR:
The integral form is:

41. Plug Flow Reactor Mole Balance
PFR:
The integral form is:
This is the volume necessary to reduce the entering molar flow rate (mol/s) from FA0 to the
exit molar flow rate of FA.

42. Packed Bed Reactor Mole Balance
PBR

43. Packed Bed Reactor Mole Balance
PBR

44. Packed Bed Reactor Mole Balance
PBR

45. Packed Bed Reactor Mole Balance
PBR

46. Packed Bed Reactor Mole Balance
PBR
The integral form to find the catalyst weight is:

47. Reactor Mole Balance Summary

48. Reactor Mole Balance Summary

49. Reactor Mole Balance Summary

50. Reactor Mole Balance Summary

51. Reactor Mole Balance Summary