iss T., Dimian a.C., Rothenberg G. Continuous Biodiesel Production

8/9/2019 iss T., Dimian a.C., Rothenberg G. Continuous Biodiesel Production

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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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[email protected] 2/24

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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a

n

k

y

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u


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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

Documents

iss T., Dimian a.C., Rothenberg G. Continuous Biodiesel Production