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Recovery of Organic Acids From Fermentation Broths
Southern Bio-Products ConferenceMarch 4-6, 2004
Beau Rivage ResortBiloxi, MS
Tim Eggeman, Ph.D., P.E.Dan Verser, Ph.D.
ZeaChem Inc.
Organic Acids - Today
Organic Acid Price, $/lb (100% Basis)
US Demand,
MM lb/yr
Common
Route
Formic 0.46 50 Synthetic
Acetic 0.42 5,286 Synthetic
Oxalic 0.38 17 Synthetic
Propionic 0.49 202 Synthetic
Lactic 0.80 176 Fermentation
Tartaric 3.00 7 Fermentation
Succinic 1.00 3 Synthetic
Maleic 0.42 478 Synthetic
Adipic 0.70 1,725 Synthetic
Citric 0.75 600 Fermentation
Points of View• Sugars:
– Inexpensive
– Under-Utilized
– More Sustainable
• Synthetic Routes will Eventually be Displaced
• Platform Viewpoint is Under-Utilized
Biology plus = Better Technology andChemistry Market Diversification
Generic Platform
RCOH
O
OrganicAcid
RCH
O
Aldehyde
RCH2OH
Alcohol
RCOR
O
Ester
CH2
Olefin
RCR
O
Ketone
R
C2 Platform
CH3COH
O
AceticAcid
CH3CH
O
Acetaldehdye
CH3CH2OH
Ethanol
CH3COCH2CH3
O
EthylAcetate
CH2
Ethylene
CH3CCH3
O
Acetone
CH2
Issues in Recovery
• pH of Broth– Unreactive Species at Near Neutral pH– Commodity Scale Production is Constrained by
Need to Avoid Salt Coproduction
• Dilute Broths– Evaporating Water is Expensive– Prefer Selective Methods for Removing
Organic Acids from Water
Effect of pH
0
10
20
30
40
50
60
70
80
90
100
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14
pH
% D
isso
ciat
ion
Dissociated AcidProtonated Acid
pKa = 4.75
BasicAcidic
Neutral
CH3COH
O
CH3CO-
O
H++
ProtonatedAcid
DissociatedAcid
pH Options
• Low pH Fermentation
• Neutral pH Fermentation– Direct Acidification– Amine Complex Formation– Other
• Bipolar Electrodialysis• Esterases
Lactic Acid - Traditional
Fermentation
Hydrolysis
EsterificationDirectAcidification
Lime
LacticAcid
Water
Ester
Water
Alcohol
SulfuricAcid
Gypsum
Sugars
Direct Acidification
Fermentation: O H2 Ca(Lac) Ca(OH) OHC 2226126
Re-acidification: 4422 CaSO HLac2 SO H Ca(Lac)
Overall: O H2 CaSO HLac2 SO H Ca(OH) OHC 244226126
US Demand for Lactic Acid = 176 MM lb/yr,Gypsum Coproduct = 252 MM lb/yr !!!
Citric Acid – Lime/Acid
Fermentation Precipitation
Acidification Crystallization
Lime
CalciumCitrate
Sugars Residue
CitricAcid
SulfuricAcid Water
Gypsum
Citric Acid – Amine Extraction
Fermentation Crystallization
Fo
rwar
d E
xtr
act
ion
Back E
xtraction
Residue
CitricAcid
Sugars
Water
Water
Formic Acid
Carbonylation HydrolysisCO
Methanol
FormicAcid
Water
Methyl Formate
Methanol
HCOH
O
H2O
CO CH3OH HCOCH3
O
Carbonylation:
Hydrolysis:
Net:
HCOCH3
O
HCOH
O
CO H2O
+
+
+
Some Common Themes
• Eliminating Salt Coproduction is Difficult– Microbiology– Careful Selection of Cations and Recovery
Scheme
• Common Purification Methods– Amine Extraction– Esterification
Routes to Ethanol
F e rm e n ta tio n :
E s te r if ic a tio n :
H y d ro g e n a tio n :
N et:
D e x tro se 3 A c e tic A c id
3 E th y l A c e ta te + 6 H 6 E th a n o l2
3 A c e tic A c id + 3 E th a n o l 3 E th y l A c e ta te + 3 H O2
D ex trose + 6 H 3 E th an ol + 3 H O22
ZeaC hem Indirect R oute
D ex trose 2 E th a n o l + 2 C O 2
D irect Ferm entation
Lab Status - Fermentation
• Lab Scale Fermentation– Strain: Moorella Thermoacetica ATCC 39073– Media: Glucose+Corn Steep Liquor
• Batch Results– First Run: 28 g/l acetate– Goal: 35-50 g/l acetate, yield = 85+% of theoretical
Lab Status - Recovery
• Lab Scale– Amine Complex Formation w/
CaCO3 Precipitation– Extraction of Amine Complex– Esterification
• Results to Date– 97+% CaCO3 Recovery– Excellent Extraction (KD > 2)– Ester Yield: 75% of Theoretical
Conclusions
• Technical Issues– pH and Avoidance of Salt Coproduction– Dilute Broths
• Advantages of Platform Viewpoint– New Routes Based on Biology and Chemistry– Market Diversification