iss t., dimian a.c., rothenberg g. continuous biodiesel production
TRANSCRIPT
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Continuous Biodiesel ProductionContinuous Biodiesel Production
Reactive Distillation Makes It HappenReactive Distillation Makes It Happen
UNIVERSITY OF AMSTERDAM
van t Hoff Institute for Molecular Sciences
Nieuwe Achtergracht 166, 1018 WV AmsterdamTel.+31-20-525.6468, E-mail: [email protected]
Web: staff.science.uva.nl/~ktony
Tony KISS, A.C. Dimian, G. Rothenberg, F. Omota
NWO/CW Project Nr. 700.54.653
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Acknowledgement
Jurriaan Beckers
Marjo C. Mittelmeijer-Hazeleger
STW Dutch Technology FoundationNWO/CW Project Nr. 700.54.653Entrainer-Based Reactive Distillation
for Synthesis of Fatty Acids Esters
Cognis, Oleon, Sulzer and Uniquema
T
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Emission type B20 = 20% biodiesel B20 B100
Total unburned hydrocarbons 20% 67%
Carbon monoxide (CO) 12% 48%
Carbon dioxide (CO2) 16% 79%
Particulate matter 12% 47%
Nitrogen oxides (NOx) +2% +10%Sulphur oxides (SOx) 20% 100%
Polycyclic Aromatic Hydrocarbons (PAH) 13% 80%
Nitrated PAH's (nPAH) 50% 90%
Biodiesel = green energy
CO2 Light CO2
Biomass Biodiesel
Biodiesel = mono-alkyl esters of fatty acids
Safe, renewable, non-toxic, biodegradable
Raw materials: vegetable oils, fat, recycled grease
Positive life cycle energy balance Positive social impact
Less emissions than regular petroleum diesel
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Project goals
Development of an active and selective solid
acid catalyst for fatty acids esterification.
Continuous biodiesel production process
based on catalytic reactive distillation.
Water-tolerant Long life
Inexpensive
Active, selective, stable Easy to use
Available on industrial scale
Catalyst requirements
O
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Applications
Why fatty esters? Food industry
Pharmaceuticals Cosmetics
Plasticizers
Bio-detergents
Bio-diesel
Cosmetics
Pharmaceuticals
Food
Bio-stuff
CH3 O
O
CH3
CH3
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Industrial key players
STEARINERIE-DUBOIS
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Process comparison
Current process
Batch esterification
High alcohol / acid ratios
Homogeneous catalysis
Difficult separation
Corrosive & toxic
Novel process
Continuous esterification
Reactive distillation
Heterogeneous catalysis
Easy separation
Environmentally friendly
Reactive distillation
Reduced investment costs
Reduced energy consumption
Increased process controllabil ity Enhanced overall rates
Steam
Water
Fatty ester
Fatty acid
Alcohol
Make up
Steam
Water
Fatty ester
Fatty acidFatty acid
AlcoholAlcohol
Make upMake up
The key to success is an active & selective solid acid catalyst.The key to success is an active & selective solid acid catalyst.
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Fatty acids & alcohols
Saturated fatty acids: CH3-(CH2)n-COOH Lauric acid (n=10)
Myristic acid (n=12) Palmitic acid (n=14)
Stearic acid (n=16)
Arachidic acid (n=18)
Unsaturated fatty acids Palmitoleic acid: CH3(CH2)5CH=CH(CH2)7COOH
Oleic acid: CH3(CH2)7CH=CH(CH2)7COOH
Aliphatic alcohols: Methanol
Ethanol
Propanol
2-Ethyl hexanol
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Reaction pathways
REACTANTSREACTANTS
Main product Secondary productsMain product Secondary products
AlcoholFatty Acid
WaterFatty Ester AlkeneEther
dehydrationetherification
esterification
Excess of alcohol
Water removal by distillation
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Reaction mechanism
O
COHR
H+
OH+
COHR
RCOOH + ROH RCOOR + H2O
Secondary reactions:
2 Alcohol
Ether + H2O Alcohol
Alkene + H2O
2 Acid
Anhydride + H2OOH+
C
OHR
HO
R'OH
C
ROH
O+H
R'
R'
HO+
OH
C
R OHH2O
R'
O
OH
CR OH2
+
OH+
COR
R'
OH+
COR
R'
O
COR
R'
H+
Catalyst
Catalyst
Similar mechanism for hetero- and homogeneous catalysis.
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Surface hydrophobicity
Influence of surface hydrophobicity on catalytic activity.
H+
OHC
O
hydrophobic surface with isolated acid site
H+
OHC
O
H+
OHC
O
H+
OHC
O
hydrophobic surface with adjacent acid si te
H+OHOH H+H+H+ H+
H+
H2O
H2OH2OH2O
H2OH2O
H2O
H2O
H2O
hydrophilic surface/ numerous acid sites
Water tolerant.
Not enough acid sites.
Water sensitive.
Easy deactivation.
Proper t rade-off
hydrophobicity-acidity.
Good catalytic activi ty.
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Solid acid catalysts
Zeolites and clays Beta, Y, MOR, ZSM-5
HeteropolyAcids
Oxides, sulphates
Composite materials Amberlyst
Nafion
Carbon-based catalysts
Polysulfonated aromatics
CH3-(CH
2)10
-COOH + C8H
15OH
CH3-(CH2)10-COOC8H15 + H2O
Dodecanoic acidDodecanoic acid 2 Ethyl2 Ethyl hexanolhexanol
Acid catalyst
2 Ethyl2 Ethyl hexylhexyl dodecanoatedodecanoate
= Not tested yet
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Catalyst screening
0
20
40
60
80
100
0 30 60 90 120
Time / [min]
Conve
rsion/[%]
Alcohol:Acid = 1:1
T=130C
H2SO4 1%wt
Non-catalyzed
Amberlyst 5%wt
Zeolites
0
20
40
60
80
100
0 30 60 90 120
Time / [min]
Conve
rsion/[%]
Alcohol:Acid = 1:1
T=150C, 3%wt catalyst
SZ
Nafion
Non-catalyzed
Amberlyst
Reaction profiles for esterif ication of dodecanoic acid with 2-ethylhexanol
Organic resins are not thermo-stable. Zeoli tes have low activity.
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Sulphated zirconia
0
20
40
60
80
100
0 20 40 60 80
Time / [min]
Conversion/[%]
Alcohol:Acid = 1:1
2%wt SZ Catalyst
Non-catalyzed
SZ 2%w
160C
180C
160C
180C
7.3% min-1
2.3% min-1
3.4% min-1
1.2% min-1
Initial rate
Non-Catalyzed
Nafion
SZ
Amber lyst
Non-Catalyzed
Nafion S
Z
Amber lyst
0
20
40
60
80
100
Conversio
n/[%]
20 min 60 min
Reaction profi les for esterif ication of dodecanoic acid with 2-ethylhexanol
0
20
40
60
80
100
Con
version/[%]
T=150C T=160C T=170C
0% 1% 2% 3%
Similar activity for esterification with 1-propanol and methanol.
SZ
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Experiments + Simulations
Integration of experimental results with simulations of thereactive distil lation (RD) setup, in AspenTech AspenPlus
RD column sections
a. Rectifying section (water)
b. Recovery of alcohol
c. Reaction zone
d. Recovery of fatty acid
e. Stripping section (ester)
Fatty acid
Alcohol
Feeds
Recycle
Reflux
Distillate
Biodiesel
a
b
d
c
e
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Thermodynamic analysis
Methanol
Tb=65 C
2-Ethylhexanol
Tb=186 C
n-Propanol
Tb=97 C
Dodecanoic acid Tb=298 C
CH3 O
O
CH3
CH3
2-Ethylhexyl dodecanoate Tb=334 C
CH3 O
OCH3
n-Propyl dodecanoate Tb=302 C
CH3 O
OCH3
Methyl dodecanoate Tb=267 C
Water
Tb=100 C
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CPE analysis
Chemical reaction
andphase equil ibrium
One liquid phase
low conversion
alcohol excess T < 100C
LLE
T < 100C
reactants molar ratio=1VLLE
T > 100C
closed system
P > 1 bar
VLE
T > 100C
open system water removal
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RD process methanol
Evaporator
Dodecanoic acid
Feed ratio 1:1
Methanol
Water 99.9 %
Distillationcolumn
Ester 99.9 %
RDC
0
0.2
0.4
0.6
0.8
1
0 0.2 0.4 0.6 0.8 1
X1(water+acid)
X2(acid+ester)
Ester, 267C Acid, 298C
Alcohol, 65C Water, 100C
0
0.2
0.4
0.6
0.8
1
0 0.2 0.4 0.6 0.8 1
X1(water+acid)
X2(acid+ester)
Ester, 267C Acid, 298C
Alcohol, 65C Water, 100C
Feasible RD process.
High purity products.
ff f fl i
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Effect of reflux ratio
Partial alcohol conversion
Highest reaction rate
Total acid conversion
Fatty acid
Alcohol
Total alcohol conversion
Highest
reaction rate
Total acid conversion
Fatty acid
Alcohol
Maximum reaction rate is located in the centreof RD column for an optimum reflux ratio
i b d fl h
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Entrainer-based RD flowsheet
98
99
100
100 150 200 250 300
Catalyst loading, kg/m3
Acid
conversion,
%
No entrainer
With entrainer
Enhanced mass transfer and reduced catalyst loading when entrainer is used.
Steam
Water
Fatty acid
Alcohol
Make up
Steam
Water
Biodiesel
Fatty acidFatty acid
AlcoholAlcohol
Make upMake upEntrainer
Feasible process. High purity products >99.9%
Reactive distillation column
Evaporator
Stripper
Decanter
RDC fil
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RDC profiles
350
400
450
500
0 5 10 15 20 25
Stage
Temperatu
re,
K
Separation zone Reaction zone Separation Reaction
0
0.2
0.4
0.6
0.8
1
0 5 10 15 20 25 30
Stage
Liquidmolefraction
1-Propanol
Water
n-Propyl acetate
Lauric acid
n-Propyl laurate
Liquid composition and temperature profiles
R ti di till ti d t
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Reactive distillation advantages
Break azeotropes
Handle difficult separations
No external recycles
Reduced investment costs
Reduced energy consumption Increased process controllability
Equilibrium shifted to products
Enhanced overall rates
Improved selectivity
Reaction Separation
C l i
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Conclusions
Surface hydrophobicity and acid sites density
determines catalyst's activity & selectivity.
Catalysts with small pores (e.g. zeolites) are not
suitable. Resins are active but not thermally-stable.
Sulphated zirconia is active, selective and stable.
Biodiesel production by reactive distillation is feasible.
GREEN ENERGY
Biodiesel