![Page 1: Lecture 24 - University of Michigan · Chemical Reaction Engineering (CRE) is the field that studies the rates and mechanisms of chemical reactions and the design of the reactors](https://reader033.vdocument.in/reader033/viewer/2022052019/60336543a5508a308667274f/html5/thumbnails/1.jpg)
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 24
![Page 2: Lecture 24 - University of Michigan · Chemical Reaction Engineering (CRE) is the field that studies the rates and mechanisms of chemical reactions and the design of the reactors](https://reader033.vdocument.in/reader033/viewer/2022052019/60336543a5508a308667274f/html5/thumbnails/2.jpg)
Today’s lecture Normal Pentene Iso-Pentane Langmuir Adsorption Isotherm Catalytic Converters for Automobiles
2
![Page 3: Lecture 24 - University of Michigan · Chemical Reaction Engineering (CRE) is the field that studies the rates and mechanisms of chemical reactions and the design of the reactors](https://reader033.vdocument.in/reader033/viewer/2022052019/60336543a5508a308667274f/html5/thumbnails/3.jpg)
Last Lecture Catalytic Reforming Reaction (Gasoline)
Normal Pentane Octane Number=62 Iso-Pentane Octane Number=90 Normal Pentane Iso-Pentane
3
![Page 4: Lecture 24 - University of Michigan · Chemical Reaction Engineering (CRE) is the field that studies the rates and mechanisms of chemical reactions and the design of the reactors](https://reader033.vdocument.in/reader033/viewer/2022052019/60336543a5508a308667274f/html5/thumbnails/4.jpg)
4
![Page 5: Lecture 24 - University of Michigan · Chemical Reaction Engineering (CRE) is the field that studies the rates and mechanisms of chemical reactions and the design of the reactors](https://reader033.vdocument.in/reader033/viewer/2022052019/60336543a5508a308667274f/html5/thumbnails/5.jpg)
Steps in a Catalytic Reaction
5
![Page 6: Lecture 24 - University of Michigan · Chemical Reaction Engineering (CRE) is the field that studies the rates and mechanisms of chemical reactions and the design of the reactors](https://reader033.vdocument.in/reader033/viewer/2022052019/60336543a5508a308667274f/html5/thumbnails/6.jpg)
Steps in a Catalytic Reaction
Adsorption on Surface
Surface Reaction Single Site
Dual Site
Desorption from Surface
6
![Page 7: Lecture 24 - University of Michigan · Chemical Reaction Engineering (CRE) is the field that studies the rates and mechanisms of chemical reactions and the design of the reactors](https://reader033.vdocument.in/reader033/viewer/2022052019/60336543a5508a308667274f/html5/thumbnails/7.jpg)
n-pentane i-pentane 0.75 wt% Pt
Al2O3
n-pentene i-pentene Al2O3
N I
n-pentane n-pentene -H2
Pt
Al2O3 i-pentene
+H2
Pt i-pentane
7
![Page 8: Lecture 24 - University of Michigan · Chemical Reaction Engineering (CRE) is the field that studies the rates and mechanisms of chemical reactions and the design of the reactors](https://reader033.vdocument.in/reader033/viewer/2022052019/60336543a5508a308667274f/html5/thumbnails/8.jpg)
8
![Page 9: Lecture 24 - University of Michigan · Chemical Reaction Engineering (CRE) is the field that studies the rates and mechanisms of chemical reactions and the design of the reactors](https://reader033.vdocument.in/reader033/viewer/2022052019/60336543a5508a308667274f/html5/thumbnails/9.jpg)
Isomerization of n-pentene (N) to i-pentene (I) over alumina
N I Al2O3
1. Select a mechanism (Mechanism Dual Site)
Adsorption on Surface:
Surface Reaction:
Desorption:
Treat each reaction step as an elementary reaction when writing rate laws.
9
![Page 10: Lecture 24 - University of Michigan · Chemical Reaction Engineering (CRE) is the field that studies the rates and mechanisms of chemical reactions and the design of the reactors](https://reader033.vdocument.in/reader033/viewer/2022052019/60336543a5508a308667274f/html5/thumbnails/10.jpg)
2. Assume a rate-limiting step. Choose the surface reaction first, since more than 75% of all heterogenous reactions that are not diffusion-limited are surface-reaction-limited. The rate law for the surface reaction step is
10
![Page 11: Lecture 24 - University of Michigan · Chemical Reaction Engineering (CRE) is the field that studies the rates and mechanisms of chemical reactions and the design of the reactors](https://reader033.vdocument.in/reader033/viewer/2022052019/60336543a5508a308667274f/html5/thumbnails/11.jpg)
3. Find the expression for concentration of the adsorbed species CI.S. Use the other steps that are not limiting to solve for CI.S (e.g., CN.S and CI.S). For this reaction,
From
From
11
![Page 12: Lecture 24 - University of Michigan · Chemical Reaction Engineering (CRE) is the field that studies the rates and mechanisms of chemical reactions and the design of the reactors](https://reader033.vdocument.in/reader033/viewer/2022052019/60336543a5508a308667274f/html5/thumbnails/12.jpg)
4. Write a Site Balance.
5. Derive the rate law. Combine steps 2, 3 and 4 to arrive at the rate law:
12
![Page 13: Lecture 24 - University of Michigan · Chemical Reaction Engineering (CRE) is the field that studies the rates and mechanisms of chemical reactions and the design of the reactors](https://reader033.vdocument.in/reader033/viewer/2022052019/60336543a5508a308667274f/html5/thumbnails/13.jpg)
13
![Page 14: Lecture 24 - University of Michigan · Chemical Reaction Engineering (CRE) is the field that studies the rates and mechanisms of chemical reactions and the design of the reactors](https://reader033.vdocument.in/reader033/viewer/2022052019/60336543a5508a308667274f/html5/thumbnails/14.jpg)
14
![Page 15: Lecture 24 - University of Michigan · Chemical Reaction Engineering (CRE) is the field that studies the rates and mechanisms of chemical reactions and the design of the reactors](https://reader033.vdocument.in/reader033/viewer/2022052019/60336543a5508a308667274f/html5/thumbnails/15.jpg)
15
![Page 16: Lecture 24 - University of Michigan · Chemical Reaction Engineering (CRE) is the field that studies the rates and mechanisms of chemical reactions and the design of the reactors](https://reader033.vdocument.in/reader033/viewer/2022052019/60336543a5508a308667274f/html5/thumbnails/16.jpg)
Placed inline with exhaust system (~$500)
NOx plays big role in smog formation
Automotive Catalytic Converters
16
![Page 17: Lecture 24 - University of Michigan · Chemical Reaction Engineering (CRE) is the field that studies the rates and mechanisms of chemical reactions and the design of the reactors](https://reader033.vdocument.in/reader033/viewer/2022052019/60336543a5508a308667274f/html5/thumbnails/17.jpg)
1) Propose a mechanism
Automotive Catalytic Converters
17
![Page 18: Lecture 24 - University of Michigan · Chemical Reaction Engineering (CRE) is the field that studies the rates and mechanisms of chemical reactions and the design of the reactors](https://reader033.vdocument.in/reader033/viewer/2022052019/60336543a5508a308667274f/html5/thumbnails/18.jpg)
(from graph data, we see CO2 is not on the surface and that the surface reaction is irreversible)
Automotive Catalytic Converters
18
![Page 19: Lecture 24 - University of Michigan · Chemical Reaction Engineering (CRE) is the field that studies the rates and mechanisms of chemical reactions and the design of the reactors](https://reader033.vdocument.in/reader033/viewer/2022052019/60336543a5508a308667274f/html5/thumbnails/19.jpg)
Automotive Catalytic Converters
19
![Page 20: Lecture 24 - University of Michigan · Chemical Reaction Engineering (CRE) is the field that studies the rates and mechanisms of chemical reactions and the design of the reactors](https://reader033.vdocument.in/reader033/viewer/2022052019/60336543a5508a308667274f/html5/thumbnails/20.jpg)
Is this consistent with the given data?
-No CO2 in rate law
-rate law decreases as PN2 increases
The contribution of PN2 is very small and can be neglected
Automotive Catalytic Converters
20
![Page 21: Lecture 24 - University of Michigan · Chemical Reaction Engineering (CRE) is the field that studies the rates and mechanisms of chemical reactions and the design of the reactors](https://reader033.vdocument.in/reader033/viewer/2022052019/60336543a5508a308667274f/html5/thumbnails/21.jpg)
optimum
Automotive Catalytic Converters
21
![Page 22: Lecture 24 - University of Michigan · Chemical Reaction Engineering (CRE) is the field that studies the rates and mechanisms of chemical reactions and the design of the reactors](https://reader033.vdocument.in/reader033/viewer/2022052019/60336543a5508a308667274f/html5/thumbnails/22.jpg)
22
![Page 23: Lecture 24 - University of Michigan · Chemical Reaction Engineering (CRE) is the field that studies the rates and mechanisms of chemical reactions and the design of the reactors](https://reader033.vdocument.in/reader033/viewer/2022052019/60336543a5508a308667274f/html5/thumbnails/23.jpg)
End of Lecture 24
23