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Chemical Reaction Engineering

Chemical Reaction Engineering. Chapter 1: General Mole Balance Equation Applied to Batch Reactors, CSTRs, PFRs, and PBRs. Chemical Identity. A chemical species is said to have reacted when it has lost its chemical identity. Chemical Identity.

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Chemical Reaction Engineering

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  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. 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

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