Lecture 6
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Lecture 6. 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 6 - Tuesday 1/25/2011. Block 1: Mole Balances Block 2: Rate Laws Block 3: Stoichiometry

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Lecture 6

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Lecture 6

Lecture 6

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 6 tuesday 1 25 2011

Lecture 6 - Tuesday 1/25/2011

  • Block 1: Mole Balances

  • Block 2: Rate Laws

  • Block 3: Stoichiometry

  • Block 4: Combine

    Review of Blocks 1, 2 and 3

    Examples : Undergraduate Reactor Experiments

    CSTR

    PFR

    BR

    Gas Phase Reaction with Change in the Total Number of Moles


Building block 1 reactor mole balance in terms of conversion

Previous Lectures

Building Block 1: Reactor Mole Balance in terms of conversion

X

Batch

t

X

CSTR

W

PFR

PBR


Lecture 6

Previous Lectures

  • Building Block 2: RateLaws

  • Power Law Model

A reactor follows an elementary rate law if the reaction orders just happens to agree with the stoichiometric coefficients for the reaction as written.

e.g. If the above reaction follows an elementary rate law

2nd order in A, 1st order in B, overall third order


Lecture 6

Previous Lectures

BuildingBlock 3:

Stoichiometry


Lecture 6

Previous Lectures

Block 4: Combine


Lecture 6

Block 4: Combine

Previous Lectures


Today s lecture

Today’slecture

  • Example for Liquid Phase Undergraduate Laboratory Experiment

    (CH2CO)2O + H2O  2CH3COOH

    A + B  2C

    Entering

    Volumetric flow rate v0 = 0.0033 dm3/s

    Acetic Anhydride7.8% (1M)

    Water92.2% (51.2M)

    Elementary with k’1.95x10-4 dm3/(mol.s)

    Case I CSTRV = 1dm3

    Case II PFRV = 0.311 dm3


Today s lecture1

Today’slecture

  • Example for Gas Phase : PFR and Batch Calculation

    2NOCl  2NO + Cl2

    2A  2B + C

    Pure NOCl fed with CNOCl,0 = 0.2 mol/dm3 follows an elementary rate law with k = 0.29 dm3/(mol.s)

    Case I PFR withv0 = 10 dm3/s

    Find space time, with X = 0.9

    Find reactor volume, V for X = 0.9

    Case IIBatch constant volume

    Find the time, t, necessary to achieve 90% conversion. Compare and t.


Part 1 mole balances in terms of conversion

Lecture 6

Part 1: Mole Balances In Terms of Conversion

Algorithm for IsothermalReactor Design

  • MoleBalance and Design Equation

  • Rate Law

  • Stoichiometry

  • Combine

  • Evaluate

    A. Graphically (Chapter 2 plots)

    B. Numerical (Quadrature Formulas Chapter 2 and appendices)

    C. Analytical (Integral Tables in Appendix)

    D. Software Packages (Appendix-Polymath)


Cstr laboratory experiment

CSTRLaboratory Experiment

Example: CH3CO2 + H20  2CH3OOH

A + B  2C

1) MoleBalance:           CSTR:


Cstr laboratory experiment1

CSTRLaboratory Experiment

3) Stoichiometry:

2) Rate Law:


Cstr laboratory experiment2

CSTRLaboratory Experiment


Cstr laboratory experiment3

CSTRLaboratory Experiment


Pfr laboratory experiment

PFRLaboratory Experiment

A + B  2C

1) MoleBalance:

2) Rate Law:

3) Stoichiometry:


Pfr laboratory experiment1

PFRLaboratory Experiment

4) Combine:


Example gas flow pfr

Example (Gas Flow, PFR)

2 NOCl 2 NO + Cl2

2A  2B + C

1) MoleBalance:

2) Rate Law:


Example gas flow pfr1

Example (Gas Flow, PFR)

A  B + ½C

3) Stoich:Gas

4) Combine:


Example gas flow pfr2

Example (Gas Flow, PFR)


Example constant volume batch

ExampleConstant Volume (Batch)

Gas Phase 2A  2B + C

1) MoleBalance:

2) Rate Law:

3) Stoich:Gas, but:


Example constant volume batch1

ExampleConstant Volume (Batch)

4) Combine:


Lecture 6

Heat Effects

Isothermal Design

Stoichiometry

Rate Laws

Mole Balance


End of lecture 6

End of Lecture 6


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