Intensified Acetone Stripping and Asymmetric Transfer ...
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Intensified Acetone Stripping and Asymmetric Transfer Hydrogenation in a Mesh Contactor A. Gavriilidis Dept of Chemical Engineering University College London
Transcript of Intensified Acetone Stripping and Asymmetric Transfer ...
Slide 1Intensified Acetone Stripping and Asymmetric Transfer
Hydrogenation in a Mesh Contactor
A. Gavriilidis Dept of Chemical Engineering University College London
Outline
– Asymmetric transfer hydrogenation in mesh reactor
– Mathematical model for stripping and reaction
– Conclusions
1
10
100
1000
10000
100000
15 20 25 30 35 40 45 50 55 Temperature, C
Va po
ur P
re ss
ur e,
P a
Acetone Isopropanol
Acetone removal
Mesh Reactor
Breakthrough Studies
Breakthrough pressure (L G)
Correlation for kl and kg
β is proportional to •overall mass transfer •liquid residence time •open area of mesh
is related to • ratio of gas flowrate over liquid flowrate • volatile component solubility
g
eq
0 50 100 150 200 250 300 Nitrogen flowrate, ml/min
C A
c, ou
t/C A
c, in
Internetmesh; dry N2; T=30oC; solvent: isopropanol; liquid inlet flowrate 0.1ml/min, P: pressure difference (Pgas-Pliquid)=30 mm H2O; Acetone concentration in the liquid inlet=0.1M
Effect of Liquid Flowrate
C A
c, ou
t/C A
c, in
Internetmesh; dry N2; T=30oC; solvent: isopropanol; Nitrogen flowrate 70ml/min, P: pressure difference (Pgas-Pliquid)=30 mm H2O; liquid inlet acetone concentration =0.1M
Acetone Stripping in Batch Reactor and Mesh Contactor
0
0.02
0.04
0.06
0.08
0.1
0.12
Contact/Residence time, min
Mesh reactor: Dry N2 flowrate: 70ml/min; P=50mmH2O; Temperature=30oC;
Batch reactor: Dry N2 flowrate: 800ml/min; Liquid volume:250ml; temperature=30oC
Acetone Stripping with Nitrogen Bubbled in IPA
0.00580.0970.0450.1020.1 0.00590.0980.0440.1020.1Bubbled in
(T=30oC; pressure difference (Pgas-Pliquid)=30 mm H2O; Nitrogen flowrate=70ml/min )
Asymmetric Transfer Hydrogenation in Batch and Mesh Reactor
0
0.2
0.4
0.6
0.8
1
Conversion
0.75
0.77
0.79
0.81
0.83
0.85
0.87
0.89
Conversion
Reaction/Residence time, min
Batch Reactor Mesh Reactor
Temperature: 30oC, [Substrate]: 0.33M, [Substrate]/[Catalyst]=1000, In mesh reactor N2=70ml/min bubbled in IPA. In batch reactor, N2 flowrate=800ml/min, Reactor volume=500ml; Reaction solution volume=250ml.
IPA Top Up During Asymmetric Transfer Hydrogenation
0
0.2
0.4
0.6
0.8
1
C on
ve rs
io n
0
0.01
0.02
0.03
0.04
0.05
0.8
0.82
0.84
0.86
0.88
0.9
Reaction conditions: Reaction temperature: 30oC, N2 flowrate: 70ml/min, [Substrate]: 0.14M; [Substrate]/[Catalyst]=1000)
Mathematical Model
Decrease of liquid flowrate
Mole balance in the gas phase
( ) i2 L
L i
M i
( ( ( ) ) )
( ) ( ) ( )
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Experimental
Experimental
Outlet Acetone Concentration, mol/l
Outlet Liquid Flowrate, ml/min
The model predicts well the behaviour of the contactor during acetone stripping from an acetone- isopropanol solution
Effect of Increasing Stripping Gas Flowrate
0.0
0.5
1.0
1.5
2.0
2.5
70 ml/min 140 ml/min 210 ml/min 280 ml/min
0
0.2
0.4
0.6
0.8
1
70 ml/min 140 ml/min 280 ml/min 210 ml/min
Dimensionless axial co-ordinate, ζ
Dimensionless axial co-ordinate, ζ
70 ml/min 140 ml/min 210 ml/min 280 ml/min
0
0.2
0.4
0.6
0.8
1
70 ml/min 140 ml/min 280 ml/min 210 ml/min
Dimensionless axial co-ordinate, ζ
Dimensionless axial co-ordinate, ζ
• Axial peak in acetone is due to isopropanol evaporation
• The stripping gas is saturated with isopropanol within the first 10% of the contactor length
Effect of Stripping Gas Presaturation with Solvent
0.2
0.4
0.6
0.8
1.0
1.2
0.7
0.8
0.9
1.0
0 L
0.7
0.8
0.9
1.0
0 L
Transverse Concentration Profiles
0.00
0.06
0.12
0.18
0.24
0.30
0.0
0.1
0.2
0.3
0.0
0.1
0.2
0.3
wall mesh-gas interface
0.00
0.06
0.12
0.18
0.24
0.30
0.0
0.1
0.2
0.3
0.0
0.1
0.2
0.3
wall mesh-gas interface
Comparison with Experiments
Conversion
0
0.2
0.4
0.6
0.8
1
Reaction / Residence Time, s
Conversion
0
0.2
0.4
0.6
0.8
1
Reaction / Residence Time, s
• Good agreement between model and experimental results for conversion
• Discrepancies possibly due to velocity variations along the height and the width of the channel
Reactant radial concentration gradients
A ce
to ph
en on
e, m
ol /l
A ce
to ph
en on
e, m
ol /l
Concluding Remarks
1. Mesh reactor is very efficient for stripping acetone from isopropanol
2. Higher gas/liquid flowrate ratio gives better acetone stripping performance
3. Bubbling nitrogen into isopropanol can prevent solvent loss
4. Mesh reactor gives better performance for acetone stripping and asymmetric transfer hydrogenation than traditional batch reactor
5. Higher enantioselectivity was obtained with isopropanol top up during the reaction than using dry nitrogen
Acknowledgements: X. Sun, M. Zanfir
EPSRC, DTI for supporting the “Micrograms to Multikilos” LINK project
http://www.centacat.qub.ac.uk/5icec/
Outline
Effect of Stripping Gas Presaturation with Solvent
Transverse Concentration Profiles
Comparison with Experiments
A. Gavriilidis Dept of Chemical Engineering University College London
Outline
– Asymmetric transfer hydrogenation in mesh reactor
– Mathematical model for stripping and reaction
– Conclusions
1
10
100
1000
10000
100000
15 20 25 30 35 40 45 50 55 Temperature, C
Va po
ur P
re ss
ur e,
P a
Acetone Isopropanol
Acetone removal
Mesh Reactor
Breakthrough Studies
Breakthrough pressure (L G)
Correlation for kl and kg
β is proportional to •overall mass transfer •liquid residence time •open area of mesh
is related to • ratio of gas flowrate over liquid flowrate • volatile component solubility
g
eq
0 50 100 150 200 250 300 Nitrogen flowrate, ml/min
C A
c, ou
t/C A
c, in
Internetmesh; dry N2; T=30oC; solvent: isopropanol; liquid inlet flowrate 0.1ml/min, P: pressure difference (Pgas-Pliquid)=30 mm H2O; Acetone concentration in the liquid inlet=0.1M
Effect of Liquid Flowrate
C A
c, ou
t/C A
c, in
Internetmesh; dry N2; T=30oC; solvent: isopropanol; Nitrogen flowrate 70ml/min, P: pressure difference (Pgas-Pliquid)=30 mm H2O; liquid inlet acetone concentration =0.1M
Acetone Stripping in Batch Reactor and Mesh Contactor
0
0.02
0.04
0.06
0.08
0.1
0.12
Contact/Residence time, min
Mesh reactor: Dry N2 flowrate: 70ml/min; P=50mmH2O; Temperature=30oC;
Batch reactor: Dry N2 flowrate: 800ml/min; Liquid volume:250ml; temperature=30oC
Acetone Stripping with Nitrogen Bubbled in IPA
0.00580.0970.0450.1020.1 0.00590.0980.0440.1020.1Bubbled in
(T=30oC; pressure difference (Pgas-Pliquid)=30 mm H2O; Nitrogen flowrate=70ml/min )
Asymmetric Transfer Hydrogenation in Batch and Mesh Reactor
0
0.2
0.4
0.6
0.8
1
Conversion
0.75
0.77
0.79
0.81
0.83
0.85
0.87
0.89
Conversion
Reaction/Residence time, min
Batch Reactor Mesh Reactor
Temperature: 30oC, [Substrate]: 0.33M, [Substrate]/[Catalyst]=1000, In mesh reactor N2=70ml/min bubbled in IPA. In batch reactor, N2 flowrate=800ml/min, Reactor volume=500ml; Reaction solution volume=250ml.
IPA Top Up During Asymmetric Transfer Hydrogenation
0
0.2
0.4
0.6
0.8
1
C on
ve rs
io n
0
0.01
0.02
0.03
0.04
0.05
0.8
0.82
0.84
0.86
0.88
0.9
Reaction conditions: Reaction temperature: 30oC, N2 flowrate: 70ml/min, [Substrate]: 0.14M; [Substrate]/[Catalyst]=1000)
Mathematical Model
Decrease of liquid flowrate
Mole balance in the gas phase
( ) i2 L
L i
M i
( ( ( ) ) )
( ) ( ) ( )
[ ]
[ ]
[ ]
[ ]
[ ]
[ ]
( ( ( ) ) )
( ) ( ) ( )
[ ]
[ ]
[ ]
[ ]
[ ]
[ ]
( ( ( ) ) )
( ) ( ) ( )
[ ]
[ ]
[ ]
[ ]
[ ]
[ ]
( ( ( ) ) )
( ) ( ) ( )
[ ]
[ ]
[ ]
[ ]
[ ]
[ ]
( ( ( ) ) )
( ) ( ) ( )
[ ]
[ ]
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( ( ( ) ) )
( ) ( ) ( )
[ ]
[ ]
[ ]
( ( ( ) ) )
( ) ( ) ( )
[ ]
[ ]
[ ]
[ ]
[ ]
[ ]
( ( ( ) ) )
( ) ( ) ( )
[ ]
[ ]
[ ]
[ ]
[ ]
[ ]
( ( ( ) ) )
( ) ( ) ( )
[ ]
[ ]
[ ]
[ ]
[ ]
[ ]
Experimental
Experimental
Outlet Acetone Concentration, mol/l
Outlet Liquid Flowrate, ml/min
The model predicts well the behaviour of the contactor during acetone stripping from an acetone- isopropanol solution
Effect of Increasing Stripping Gas Flowrate
0.0
0.5
1.0
1.5
2.0
2.5
70 ml/min 140 ml/min 210 ml/min 280 ml/min
0
0.2
0.4
0.6
0.8
1
70 ml/min 140 ml/min 280 ml/min 210 ml/min
Dimensionless axial co-ordinate, ζ
Dimensionless axial co-ordinate, ζ
70 ml/min 140 ml/min 210 ml/min 280 ml/min
0
0.2
0.4
0.6
0.8
1
70 ml/min 140 ml/min 280 ml/min 210 ml/min
Dimensionless axial co-ordinate, ζ
Dimensionless axial co-ordinate, ζ
• Axial peak in acetone is due to isopropanol evaporation
• The stripping gas is saturated with isopropanol within the first 10% of the contactor length
Effect of Stripping Gas Presaturation with Solvent
0.2
0.4
0.6
0.8
1.0
1.2
0.7
0.8
0.9
1.0
0 L
0.7
0.8
0.9
1.0
0 L
Transverse Concentration Profiles
0.00
0.06
0.12
0.18
0.24
0.30
0.0
0.1
0.2
0.3
0.0
0.1
0.2
0.3
wall mesh-gas interface
0.00
0.06
0.12
0.18
0.24
0.30
0.0
0.1
0.2
0.3
0.0
0.1
0.2
0.3
wall mesh-gas interface
Comparison with Experiments
Conversion
0
0.2
0.4
0.6
0.8
1
Reaction / Residence Time, s
Conversion
0
0.2
0.4
0.6
0.8
1
Reaction / Residence Time, s
• Good agreement between model and experimental results for conversion
• Discrepancies possibly due to velocity variations along the height and the width of the channel
Reactant radial concentration gradients
A ce
to ph
en on
e, m
ol /l
A ce
to ph
en on
e, m
ol /l
Concluding Remarks
1. Mesh reactor is very efficient for stripping acetone from isopropanol
2. Higher gas/liquid flowrate ratio gives better acetone stripping performance
3. Bubbling nitrogen into isopropanol can prevent solvent loss
4. Mesh reactor gives better performance for acetone stripping and asymmetric transfer hydrogenation than traditional batch reactor
5. Higher enantioselectivity was obtained with isopropanol top up during the reaction than using dry nitrogen
Acknowledgements: X. Sun, M. Zanfir
EPSRC, DTI for supporting the “Micrograms to Multikilos” LINK project
http://www.centacat.qub.ac.uk/5icec/
Outline
Effect of Stripping Gas Presaturation with Solvent
Transverse Concentration Profiles
Comparison with Experiments
