1 Strategies for the conversion of biomass to bioethanol and - PowerPoint Presentation

1. 1Strategies for the conversion of biomass to bioethanol and biochemicalsDr P Indra NeelProfessor Tae Hyun Kim’s groupDepartment of Environmental EngineeringKongju National UniversityKorea

2. The conversion of potato starch to ethanol in a single-step process Aqueous starch solution (5 wt %) and amylase mixture were charged into the reactor bed loaded with instant baker’s yeast (Saccharomyces cerevisiae)Top flat glass surface allowed the solar radiation into the reactor Fermentation took place in the first chamber and the produced ethanol was continuously separated from the yeast bed by evaporation-condensation (at 30-35 °C) processThe ethanol droplets condensed on the glass were collected into the second chamber Simultaneous saccharification and fermentation (SSF) of starchStarch Liquefied starch GlucoseEthanol Hydrolysis(α-amylase)Hydrolysis(glucoamylase)Fermentation(microorganisms)Fermentation broth outletyeast2

3. Solar-energy-driven fermentation has numerous advantages: No external source of heating High ethanol yields without electricity consumption Using the same microorganism for a long time without loss in the activity No additional energy input for ethanol separation Micro organisms not supplemented by nutrientsNo requirement of use of buffer No polluting effluent produced in the process Insitu reduction of glycerol to 1, 3 propane diol Utilization of solar energy for driving the process and in situ separation of ethanol from the fermentation broth make the current process economically feasible and environment-friendly, which is industrially appealing and adoptable The produced bioethanol was also demonstrated as a potential fuel for DEFCsAdvantages over existing technology3

4. 41H NMR spectra of the starch fermentation product on the (a) 7th, (b) 14th, (c) 21st, and (d) 28th dayInset shows the ethanol peaks—a 3H (t) at 1.2 ppm and a 2H (q) at 3.7 ppmSinglet peak at 8.4 ppm is the internal standard, HCOONa, and the peak at 4.8 ppm is the solventAnalysis of products of SSF of starch13C NMR spectra of (a) authentic ethanol and the starch fermentation product on the (b) 7th, (c) 14th, (d) 21st, and (e) 28th dayNo other reaction by-products (glycerol oracetic acid) were observed in the analytes indicating the purityIntense signals seen in all four samples at17 and 58 ppm are characteristic of ethanolThe reaction product is devoid of the reactant (starch), reaction intermediate (glucose), and the usual secondary metabolites of fermentation (glycerol andacetic acid)

5. Mass balance studies for the conversion of starch to ethanol84 % of the theoretical ethanol yield was collected over 63 days (from the outlet)Initial amount of starch: 5 wt % = 80 g starch in 1.6 L solutionExpected yield of glucose: 1 g starch converts to 1.1 g glucose 80 g starch should convert to 88.8 g glucoseExpected yield of ethanol: 1 g glucose yields 0.51 g ethanol 88.8 g glucose should yield 45.28 g ethanolActual yield of ethanol after 63 days: 38 g ethanol = (38/45.28) x 100 = 84 % yieldThe concentration of ethanol varied in the range of 1.8-2.6 wt. % over the course of study5

6. The potential of starch-based bioethanol for direct ethanol fuel cells applicationsSSF was scaled up to 15 wt. % starch to be evaluated as fuel in DEFCsVoltammograms of as-produced bioethanol (1.3 M, 6 wt %) and commercial ethanol were similar, with comparable peak currents (high purity level) A well-defined ethanol oxidation peak was observed at 0.75 V, with no additional impurity peaksThe cell performance increased with temperature due to the enhanced kinetics of ethanol oxidation at the anode and oxygen reduction at the cathode 6

7. SSF of starch to bioethanolA leap towards decentralized power supply7ChemSusChem 2015, 8, 3497 – 3503

8. Continuous-flow bioethanol production in the solar reactor The batch process was further developed to a continuous-flow bioethanol production The reactor was fed with 2 L of 10, 20, 30 or 40 wt.% aqueous glucose solutions (2.8 mL/h flow rate) For each glucose feed, the process was monitored for a month in the reactor at 20-25 °C The yeast was not supplemented with any additional nutrients (only glucose feed) The yeast bed was always in solid-state condition8

9. Time on stream studies of ethanol yield High ethanol yields (91, 86, 89, and 88% of the theoretical yield) indicate the atom efficiency of the process No effluent in the reactor (very convenient to change the feed solutions between the experiments) There was almost no loss in the activity of the yeast even after two months of continuous operation of the process9

10. Application of solar-energy-driven bioethanol – electricity generation 2 M ethanol produced through solid-state continuous-flow fermentation of 20 wt% aqueous glucose solution was tested in alkaline-acid DEFCs for its potential as fuel The enhanced performance at 333 K is attributed to the faster electrochemical kinetics of the redox reactions (ethanol oxidation and H2O2 reduction), improved membrane conductivity, increased reactant delivery and product removal rates The as-produced bioethanol was demonstrated as a potential fuel with current and power density values as high as 700 mA/cm2 and 330 mW/cm2 When the operating temperature increased from 303 to 333 K, the power density increased from 330 to 410 mW/cm2 The OCV was observed to be 1.65 V at both operating temperatures (65.5% voltage efficiency)10

11. 11RSC Adv., 2016, 6, 24203–24209

12. To monitor the SSF process of starch and to know about the reaction intermediates and by-products, analytes were collected from the fermentation broth on the 7th and 60th day As expected, glucose (reaction intermediate), glycerol (secondary metabolite), and ethanol (reaction product) were present in 7th day sampleNo traces of starch (reactant) or glucose (reaction intermediate) were observed in the 60th day sample, indicating the complete conversion of starch to ethanolThe 60th day sample was quite surprising as no trace of glycerol was observed Instead of glycerol, its reduced product 1,3-propanediol was observed on the 60th day In situ reduction of glycerol to 1,3-propanediol by Baker’s yeast7th day60th day12

13. In situ reduction of glycerol to 1,3-propanediol by baker’s yeast1,3-propanediol is a value-added product usually produced from the bioreduction of glycerolMany microorganisms are able to metabolize glycerol in the presence of respiratory metabolism but few are fermentativeThe fermentative metabolism of glycerol was studied in great detail for several species of the Enterobacteriaceae family (such as Citrobacter freundii and Klebsiella pneumoniae) Dissimilation of glycerol in these organisms is strictly linked to their capacity to synthesize the highly reduced product 1,3-propanediolWe are the first group reporting on the potential of a fungal strain (baker’s yeast) converting glycerol to 1,3-propanediol 13

14. 14Various glycerol fermentation conditions (aerobic, semi-aerobic, and anaerobic) were tested at different reaction temperatures (25, 30, and 37 °C). Under optimal reaction conditions (anaerobic fermentation at 25 °C), 42.3 wt % 1,3-propanediol yield was achieved with 93.6 wt% glycerol conversionProduction of 1,3-propanediol from glycerol via fermentation by Saccharomyces cerevisiae

15. 15Yield (wt %) of 1,3-propanediol and other metabolites through fermentation (aerobic, semi-aerobic and anaerobic) of glycerol (0.1 M) by Saccharomyces cerevisiae (3 g) at (A) 25, (B) 30, and (C) 37 °C on the 30th dayGreen Chem., 2016, 18, 4657–4666

16. 16Work planWork plan 1: Development of an effective pretreatment methodology for biomass fractionation. (NH4)2CO3 could be a potential pretreating agent for the separation of lignin and hemicellulosefrom biomass in a single step under modest operating conditions in a continuous flowProcess. Work plan 2: Production of levulinic acid from cellulose derived from pretreated biomass(rice straw, corn stover, sweet sorgham, miscantus) using solid acid (heteropoly acids and zeolites) as catalysts in a continuous flow reactorWork plan 3:Production of furfural from xylose (commercial) and from hemicellulose isolated from biomass using metal oxides (CuO, ZnO, NiO, heteropoly acids, zeolites) as catalysts. Use of CuPW12O40 supported on activated carbon could be promisingCatalyst for furfural production.

17. 17Work plan 4: Production of phenolic compounds from lignin (commercial) as well as ligninisolated from biomass (rice straw, corn stover, wheat straw) using SrO as catalystunder hydrothermal and sonochemical conditions.Work plan 5:Strategies for the conversion of glycerol to the hydrogenolysis product (1, 3-Propane diol) via catalytic path ways.Work plan 6:Constructing a solar reactor with woodFlowing the aq. suspension of hemicellulose isolated from biomass (rice straw, corn stover, sweet sorgham (5-10 wt.%) through the reactor bedPacking of the solar reactor bed with Saccharomyces cerevisiae (Baker’s yeast),E-coli, amylases and cellulaseEstimation of ethanol concentration using HPLCEstimation of the conc. of secondary metabolites (1, 3 propane diol and others)using HPLCWork plan 7:H2 production from glucose fermentation in a solar reactor

18. 18AcknowledgementsGrateful thanks are due to Professor Aharon Gedanken, Israel, for the valuableguidance and support.

19. Thank You19