1. Chemical Reaction Engineering (CRE) is the field that studies the rates and mechanisms of chemical reactions and the design of the reactors in which they take place. Lecture 8

2. Lecture 8 – Tuesday 2/1/2011 Liquid Phase Reactions: Pressure Drop does not affect the concentrations in liquid phase rxn. Gas Phase Reactions: Epsilon not Equal to Zero d(P)/d(W)=. Polymath will combine with d(X)/f(W)=..for you Epsilon = 0 and Isothermal P=f(W) Combine then Separate Variables (X,W) and Integrate Engineering Analysis of Pressure Drop 2

3. Gas Phase Flow System: Concentration Flow System: 3

4. Note: Pressure drop does NOT affect liquid phase reactions Sample Question: Analyze the following second order gas phase reaction that occurs isothermally in a PBR: A  B Must use the differential form of the mole balance to separate variables: Second order in A and irreversible: 4

5. Stoichiometry: Isothermal, T=T 0 Combine: Need to find (P/P 0 ) as a function of W (or V if you have a PFR) 5

6. Ergun Equation: 6 Constant mass flow:

7. Variable Density Let 7

8. Catalyst Weight Where Let 8

9. We will use this form for single reactions: Isothermal case 9

10. andor 10

11. 11

12. W P 1 12

13. CACA W 13 2

14. -r A W 14 3

15. X W 15 4

16. W 1.0 16 5

17. 17

18. Gas Phase Reaction in PBR with δ = 0 (Analytical Solution) A + B  2C Repeat the previous one with equimolar feed of A and B and k A = 1.5dm 6 /mol/kg/min α = 0.0099 kg -1 Find X at 100 kg 18

19. 1) Mole Balance: 2) Rate Law: 3) Stoichiometry: 19

20. , 20, 4) Combine:

21. 21

22. Polymath Solution A + 2B  C is carried out in a packed bed reactor in which there is pressure drop.The fed is stoichiometric in A and B. Plot the conversion and pressure ratio y = P/P 0 as a function of catalyst weight upto 100 kg. Additional Information k A = 6dm 9 /mol 2 /kg/min α = 0.02 kg -1 22

23. A + 2B  C 1) Mole Balance: 2) Rate Law: 3) Stoichiometry: Gas, Isothermal 23

24. 4) 5) 6) 7) Initial values: W=0, X=0, y=1  W=100 Combine with Polymath. If δ ≠0, polymath must be used to solve. 24

25. 25

26. 26

27. 27 T = T 0

29. 29

30. 30

31. 31

32. Mole Balance Rate Laws Stoichiometry Isothermal Design Heat Effects 32

33. End of Lecture 8 33

34. Use for heat effects, multiple rxns Isothermal: T = T 0 34

35. A + B  2C Case 1: Case 2: 35

36. 36