1. Carboxylic acids to biofuels via syngas fermentation
CCTEC sixth annual Cornell Technology Venture Forum™ (CTVF) on October 25, 2012 in the East Hill Office Building Training Room and Atrium (395 Pine Tree Road, Ithaca, NY)
Carboxylic acids to biofuels via syngas fermentation
Hanno Richter, Michael E. Martin, and Largus T. Angenent
Cornell University, Biological & Environmental Engineering, Ithaca, NY 14853
Carboxylic acid conversion
in batch syngas reactors
Continuous syngas fermentation with gas-
and cell recycling for increased productivity
ABSTRACT
Short chain carboxylic acids such as n-butyric acid have been suggested as potential precursors for production of biofuels, e.g. n-butanol (Dwidar et al., The Scientic World Journal doi: /2012/471417). Our lab has developed the carboxylate platform, a fermentation technology with open cultures of microbial consortia that generates short-chain carboxylic acids, such as n-butyric acid (Agler et al., Environ. Sci. Technol. 46(18): ), or n-caproic acid (Agler et al., Energy Environ. Sci. 5: ) as end-products. Also this year, we have published a manuscript on the conversion of n-butyric acid into n-butanol using glucose as a source of electrons and energy (Richter et al., Biotechnol Bioeng. 109(4): ).
In August 2012, we have submitted another manuscript to Biotechnology & Bioengineering, and filed a patent for the invention of a technology that uses carbon monoxide and hydrogen (potentially derived from biomass pyrolysis), as a source of electrons and energy for microbial conversion of short-chain carboxylic acids, such as n-butyric acid and n-caproic acid, into their corresponding alcohols (n-butanol and n-hexanol, respectively). Results of that latest innovation and on improvement of syngas fermentation efficiency are presented here.
* OD600
+ pH
● butyrate
□ acetate
● butanol
▪ ethanol
Clostridium ljungdahlii in anaerobic batch
reactors, continuously sparged with syngas
Formation of products in syngas-
reactors with 15 mM n-butyric acid
Table: range of substrates tested (15 mM); results for 2 different microbial species
effluent
Pumps
Growth
medium
Microbubbles, required
for efficient mass transfer
pH control
Stage II
Stage I
Parameters for 2nd fermentation stage
Overview
Rates of
mMol/(L*min)
g/(L*h)
CO in
0.808
1.357
CO out
0.110
0.185
CO consumption
0.698
1.172
H2 in
0.471
0.057
H2 out
0.085
0.010
H2 consumption
0.386
0.046
CO2 in
0.067
0.177
CO2 out
0.371
0.979
CO2 production
0.304
0.803
Ethanol production
0.136
0.375
Acetic acid production
0.025
0.090
Species Concentration stage 2
inlet outlet
CO (g)
60 vol%
19 vol%
H2 (g)
35 vol%
14 vol%
CO2 (g)
5 vol%
63 vol%
Ethanol (l)
428 mM
(19.7 g/L)
Acetic acid (l)
143 mM
(8.6 g/L)
Gasification
Syngas (CO, H2, CO2)
CO2
Lignocellulose
N-butyric Acid
N-butanol
Carboxylate
platform
Solvento-
genic
Clostridium
Efficiency (%)
Stage 2
CO consumption 86
H2 consumption 82
CO recovery in etOH
28*
CO recovery in acetic acid 5*
FUNDING
The presentation focuses on the conversion of carboxylic acids into alcohols (highlighted here).
Yossie Hollander and the Foundation de Fondateurs
Northeastern SunGrant Initiative
Achieved: An ethanol productivity,
Ca. 10% of yeast in biofuel plants.
* Syngas consumption of stage 1 is
considered