Chemical Reaction Engineering

Chapter 3, Part 4:

Reaction Stoichiometry

Measures Other Than Conversion

Measures Other Than Conversion

Uses: A. Membrane reactors

B. Multiple reaction

Liquids: Use concentrations, i.e., CA

C A FA

0

Measures Other Than Conversion

Uses: A. Membrane reactors

B. Multiple reaction

Liquids: Use concentrations, i.e., CA

1. For the elementary liquid phase reaction carried out in a CSTR, where V, vo,CAo,k, and Kc are given and the feed is pure A, the combined

mole balance, rate laws, and stoichiometry are:

C A FA

0

A B

rA k C A CB

K C

Measures Other Than Conversion

Uses: A. Membrane reactors

B. Multiple reaction

Liquids: Use concentrations, i.e., CA

1. For the elementary liquid phase reaction carried out in a CSTR, where V, vo,CAo,k, and Kc are given and the feed is pure A, the

combined mole balance, rate laws, and stoichiometry are:

C A FA

0

A B

C A0 CA

rA

VFA0 FA

rA

0 C A 0 C A rA

rA k C A CB

K C

Measures Other Than Conversion

Uses: A. Membrane reactors

B. Multiple reaction

Liquids: Use concentrations, i.e., CA

1. For the elementary liquid phase reaction carried out in a CSTR, where V, vo,CAo,k, and Kc are given and the feed is pure A, the

combined mole balance, rate laws, and stoichiometry are:

C A FA

0

A B

C A0 CA

rA

VFA0 FA

rA

0 C A 0 C A rA

CA 0 C A

k CA CB

K C

rA k C A CB

K C

Measures Other Than Conversion

Uses: A. Membrane reactors

B. Multiple reaction

Liquids: Use concentrations, i.e., CA

1. For the elementary liquid phase reaction carried out in a CSTR, where V, vo,CAo,k, and Kc are given and the feed is pure A, the

combined mole balance, rate laws, and stoichiometry are:

C A FA

0

A B

C A0 CA

rA

VFA0 FA

rA

0 C A 0 C A rA

CA 0 C A

k CA CB

K C

V FB 0 FB

rB

0 C B 0 C B

rB

rA k C A CB

K C

Measures Other Than Conversion

3s, C A 0 2 mol dm3 , K C 10, k 0.1s 1

Measures Other Than Conversion

C B0 CB

rB

0 CB

rB

C B

rA

C B

rA

C B

k CA C B

KC

C B

k CA CB

K C

3s, C A 0 2 mol dm3 , K C 10, k 0.1s 1

Measures Other Than Conversion

C B0 CB

rB

0 CB

rB

C B

rA

C B

rA

C B

k CA C B

KC

2. There are two equations, two unknowns, CA and CB

3s, C A 0 2 mol dm3 , K C 10, k 0.1s 1

C B

k CA CB

K C

Measures Other Than Conversion

• Gases: Use molar flow rates, i.e., FI

C T FT

PRT

, CT 0 FT 0

0

P

RT0

Measures Other Than Conversion

• Gases: Use molar flow rates, i.e., FI

C T FT

PRT

, CT 0 FT 0

0

P

RT0

Measures Other Than Conversion

• Gases: Use molar flow rates, i.e., FI

C T FT

PRT

, CT 0 FT 0

0

P

RT0

Measures Other Than Conversion

• Gases: Use molar flow rates, i.e., FI

C A C T0

FA

FT

PP0

T0

T , CT 0 P0

RT0

C T FT

PRT

, CT 0 FT 0

0

P

RT0

Measures Other Than Conversion

• Gases: Use molar flow rates, i.e., FI

If the above reaction, ,carried out in the gas phase in a PFR, where V, vo,CAo,k, and Kc are given and the feed is pure A, the combined

mole balance, rate laws, and stoichiometry yield, for isothermal operation (T=To) and no pressure drop (P=0) are:

C A C T0

FA

FT

PP0

T0

T , CT 0 P0

RT0

C T FT

PRT

, CT 0 FT 0

0

P

RT0

rA k C A CB

K C

Measures Other Than Conversion

• Gases: Use molar flow rates, i.e., FI

If the above reaction, ,carried out in the gas phase in a PFR, where V, vo,CAo,k, and Kc are given and the feed is pure A, the combined

mole balance, rate laws, and stoichiometry yield, for isothermal operation (T=To) and no pressure drop (P=0) are:

C A C T0

FA

FT

PP0

T0

T , CT 0 P0

RT0

C T FT

PRT

, CT 0 FT 0

0

P

RT0

rA k C A CB

K C

Measures Other Than Conversion

• Gases: Use molar flow rates, i.e., FI

If the above reaction, ,carried out in the gas phase in a PFR, where V, vo,CAo,k, and Kc are given and the feed is pure A, the combined mole

balance, rate laws, and stoichiometry yield, for isothermal operation (T=To) and no pressure drop (P=0) are:

C A C T0

FA

FT

PP0

T0

T , CT 0 P0

RT0

C T FT

PRT

, CT 0 FT 0

0

P

RT0

Use Polymath to plot FA and FB down the length of the reactor.

rA k C A CB

K C

Measures Other Than Conversion

Use Polymath to plot FA and FB down the length of the reactor.

Given:

V0 30 dm 3 , 0 10 dm 3 s, K C 10, k 0.1s 1

Measures Other Than Conversion

Use Polymath to plot FA and FB down the length of the reactor.

Given:

V0 30 dm 3 , 0 10 dm 3 s, K C 10, k 0.1s 1

V

FA

FB

Summary

At the start of the chapter we saw we needed -rA=f(X). This result is achieved in two steps.

Summary

At the start of the chapter we saw we needed -rA=f(X). This result is achieved in two steps.

1. Rate Laws

– -rA=k f(Ci)

– 1st order A--> B or 1st order

-rA=kCA

rA k C A C B

KC

Summary

At the start of the chapter we saw we needed -rA=f(X). This result is achieved in two steps.

1. Rate Laws

– -rA=k f(Ci)

– 1st order A--> B or 1st order

– 2nd order A+B --> C

– Rate laws are found by experiment

-rA=kCA

rA k C A C B

KC

-rA=kACACB

Summary

At the start of the chapter we saw we needed -rA=f(X). This result is achieved in two steps.

1. Rate Laws

– -rA=k f(Ci)

– 1st order A--> B or 1st order

– 2nd order A+B --> C

– Rate laws are found by experiment

2. Stoichiometry

– Liquid:

– Gas:

-rA=kCA

rA k C A C B

KC

-rA=kACACB

C A CA 0 1 X

C A CA 0 1 X

1 X PP0

T0

T

C A CT 0

FA

FT

PP0

T0

T