Hydrothermal pretreatment of biomass for ethanol fermentation

Transcription

1 Hydrothermal pretreatment of biomass for ethanol fermentation Yukihiko Matsumura Hiroshima University 1 Dec , 2012 JAPANESE-DANISH JOINT WORKSHOP Future Green Technology Hakata, Japan

2 緒言 First and second generation ethanol First generation Second generation Sugar, Starch, grain Easy fermentation to bioethanol High price raw material Competition with foods Lignocellulosic residues (wood, straw) and other agricultural residues Advanced technology is needed 2

3 緒言 Saccharification of lignocellulosics Lignocellulosics CH 2 OH HO CH 2 OH OH O OH O CH 2 OH OH O OH O n-2 Cellulose CH 2 OH O OH OH OH Pretreatment H H OH OH H H OH OH Glucose H Hemicellulose Lignin Enzymatic hydrolysis Ethanol fermentation Ethanol 3 3

4 Various pretreatment for saccharification Pretreatment Concept Disadvantage Author (year) Previous study Concentrated sulfuric acid Promote hydrolysis with concentrated sulfuric acid Decomposition of glucose by acid Gupta R et al. (2009) High cost to use acids Dilute sulfuric acid Promote hydrolysis with dilute sulfuric acid High cost to treat byproducts Reactor corrosion Root et al. (1959) Steam explosion After heating up in steam, suddenly reduce the pressure Low glucose yield DeLong (1981) Pulverization Decrease the crystallinity of cellulose Large amount of energy needed. Sidiras and Koukios (1989) Hydrothermal 4 Hemicellulose is dissolved in water by high temperature and pressure. Reduction of crystallinity of cellulose. Low cost Low glucose yield Mok and Antal (1994)

5 Inhibitor byproducts for fermentation Lignocellulosic biomass Cellulosic component Monosaccharide Ethanol Hydrothermal Pretreatment Enzymatic hydrolysis Ethanol fermentation Inhibitors 5

6 Fermentation inhibitors Yeast Saccharomyces cerevisiae Aerobic Anaerobic Cell growth Ethanol fermentation Fermentation inhibitors are produced during hydrothermal pretreatment, which affects the activities of the yeast Inhibitors Formic acid, Acetic acid, Furfural, 5-HMF 6

7 Purpose To commercialize the process, reaction characteristics as well as inhibitor effect should be clarified. but This evaluation has not been reported so far. Purpose of this study The purpose of this study is to determine the reaction characteristics and inhibitor effect quantitatively. 7

8 Experimental for hydrothermal pretreatment Raw material Rubber wood residues Filtration Hydrothermal pretreatment Liquid fraction Solid fraction Glucose product Enzymatic hydrolysis Glucose product Autoclave reactor 8 Reactant Buffer fluid Enzymatic hydrolysis 1 g 60 ml 10 g/l cellulase solution 5 ml The working volume of the pretreatment vessel was 96 ml. The pretreatment agitator was set at 500 rpm. Cellulase from Aspergillus niger powder, 0.3 units/mg solid The flasks were shaken at 250 rpm at 37 C HPLC with SUGAR K S-802(Shodex) column operated at 60 C with 0.8mL/min flow of water as an eluate. The detector was a refractive index

9 Temperature [ ] Experimental conditions Temperature Rubber wood powder De-ionized water 130, 150, 170, 190, 200, 210, 240, 260 and 280 o C 7 g 63 g Time [min] 130 C 140 C 150 C 170 C 190 C 200 C 210 C 240 C 260 C 280 C Temperature history for different target temperatures. 9

10 Feedstock Rubber wood residue 37% of market share export of the world are from Thailand CHEMICAL CHARCTERISTICS OF RUBBER WOOD RESIDUE Composition % hemicelluloses 29 lignin 28 cellulose 39 ash 4 United States Department of Agriculture, Forage fiber analyses (Apparatus, reagents, procedures, and some applications), Agriculture Handbook, 379 (1970) 10

11 Yield [-] Products and saccharification HC 130 C HC 140 C HC 150 C HC 170 C HC 190 C HC 200 C HC 210 C HC 240 C HC 250 C HC 260 C A A B B C D E C D E Time of cellulase reaction [hour] HC 280 C Time dependence of amount of glucose generated from solid residue treated temperature o C, 10 wt% of concentration of raw material, treatment time 0 min. (HC denote the solid sample from hydrothermal pretreatment used with enzymatic hydrolysis) The samples after hydrothermal pretreatment at temperature on 130 (A), 140 (B), 150 (C), 170 (D), and 190 C (E) 11

12 Hydrothermal pretreatment Cellulase treatment Reaction modeling C D G C* C D G C* C k 1 C G D C* k 2 k 4 k 3 k = A exp( - E / RT ) C Cellulose C* Cellulose hydrolyzed by cellulase after pretreatment G Glucose D Decomposition products of glucose 12

13 Yield [-] Reaction rate parameters d[ C] dt k1[ C] k2[ C] d[ C*] dt k1[ C] k3[ C*] d[ G] dt k3[ C*] k2[ C] k4[ G] d[ D] dt k [ G 4 ] D C C* Temperature [ o C] G Reaction rate parameters Preexponential factor [1/s] Activation energy [kj/mol] k k k k

14 Yield [-] Yield [-] Yield [-] Yield [-] Comparison with other feedstocks Cabbage Kenaf C C* G D C C* G D Pretreatment Temp [ ] Pretreatment Temp [ ] EFB Pretreatment Temp [ ] C C* G D C C* Temperature [ o C] D G

15 緒言 Conclusions (reaction characteristics) Model for the reactions in hydrothermal pretreatment reactor was proposed. The reaction parameter in the hydrothermal reactor for rubber wood was successfully decided. Reaction characteristics differs from feedstock to feedstock. 15

16 Experiment 緒言 for inhibitor effect clarification incubator Yeast 0.2 ml Fermentatio n inhibitor 14 ml vial 5 wt%ypd 10 ml rotary shaker, 30 OD at 600 nm Glucose and ethanol concentration by HPLC 16

17 緒言 Experimental conditions Yeast YPD medium (5.0 wt%) Preculture Inhibitor concentration Formic acid Acetic acid, Furfural 5-HMF Measuring time Incubation temperature S. cerevisiae * 10 ml 0.2 ml 0-45 mm 0-45 mm 0-45 mm 0-15 mm 36 h 30 o C 17 *Sigma-Aldrich (Type II)

18 緒言 Cell growth model OD at 600 nm ( t τ) μ=μ max dx dt ds dt 1 μ max S μ X k X:Cell concentration X 0 :Initial Cell concentration S:Culture medium concentration S 0 :Initial culture medium concentration t: Incubation time 18 S dx dt K (Monod equation) K X K (1 )ln ln1 kxo So Xo kxo So τ (1) (2) (3) K μmax Time [h] (1) Lag phase (2) Exponential growth phase (3) Resting phase k So Xo μ max : Maximum growth rate K:Half medium concentration rate k: τ: Lag phase time X k

19 OD at 600 nm [-] 緒言 Inhibitor effect on cell growth OD at 600 nm [-] mm 15 mm mm 0 mm 15 mm mm mm mm Time [h] Time [h] Formic acid Acetic acid 19

20 OD at 600 nm [-] 緒言 Inhibitor effect on cell growth OD at 600 nm [-] mm 15 mm mm 5 mm 10 mm 15 mm mm Time [h] 45 mm Time [h] 20 Furfural 5-HMF

21 k/s0 [-] τ [h] μmax [1/h] K/S0 [-] 緒言 Monod parameter change by inhigibors Formic acid Acetic acid Furfural 5-HMF Concentration [mm] Concentration [mm] Concentration [mm] Concentration [mm]

22 Concentration [mol/l] 緒言 Inhibitor effect on ethanol fermentation Concentration [mol/l] Ethanol Glucose 0 mm 15 mm 30 mm 45 mm Time [h] Time [h] Formic acid Acetic acid

23 Concentration [mol/l] 緒言 Inhibitor effect on ethanol fermentation Concentration [mol/l] Furfural 0 mm 15 mm 30 mm 45 mm 5-HMF 0 mm 5 mm 10 mm 15 mm Ethanol Glucose Time [h] Time [h] Furfural 5-HMF

24 緒言 Conclusions (inhibitor effect) The inhibitors used in this study slows cell growth and final yeast concentration. Effect on parameters were observed (μ max, k, τ). The inhibitors used in this study except acetic acid decreases glucose consumption rate and ethanol production rate for ethanol fermentation. Acetic acid affects cell growth but does not affect ethanol production. 24

25 緒言 Acknowledgment This study was supported by the following funds. Ministry of Education Collaborating bodies Tawatchai Charinpanitkul (Chulalongkorn University) Staffs and Students Takuya Yoshida, Machi Kanna, Takashi Yanagida Phacharakamol Petchpradab Yuta Fukutomi 25

26 緒言 Thank you!! 26 See you at the European Biomass Conf. and Exhibition, 3-7 June 2013 Bella Center - Copenhagen, Denmark