Biofuels in Perspective

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5 4 3 2 Enzymatic Production of Biodiesel 139 Figure 8.8 Schematic diagram of packed-bed reactor. (1) Ultrasonic device, (2) magnetic stirring machine, (3) reservoir of substrates, (4) peristaltic pump, (5) Tygon tube, (6) glass column packed bed (25 mm � × 400 mm H ) with whole cell biocatalysts, and (7) products. concentration of immobilized cells in the BSPs decreased significantly from 2.11 mg/BSP to 0.93 mg/BSP after the tenth cycle. These results suggest that a packed-bed reactor operated at an appropriate circulation flow rate offers a significant advantage in repeated methanolysis reaction by protecting cells from physical damage. 8.4.3 Effect of Fatty Acid Cell Membrane Composition To stabilize the lipase activity of R. oryzae cells as whole-cell biocatalysts, Hama et al. 50 investigated the effect of cell membrane fatty acid composition on biodiesel fuel production. They found that oleic or linoleic acid-enriched cells showed higher initial methanolysis ME content (wt.%) 100 80 60 40 20 0 0 100 200 300 400 500 600 700 Reaction time (h) Figure 8.9 Time course of methyl ester content during ten repeated cycles in packed-bed reactor. 1 6 7
140 Biofuels Ratio of initial reaction rate (-) 100 80 60 40 20 0 0.0 0.5 1.0 Fatty acid ratio indicated by R f (-) Figure 8.10 Effect of fatty acid ratio (R f) on development of initial reaction rate and methyl ester content. Left-hand scale shows ME content after 2.5-h in second batch cycle as percentage of that in first. (From Ref. 50, with permission of Elsevier.) activity than saturated fatty acid-enriched cells, among which palmitic acid-enriched cells exhibited significantly greater enzymatic stability than unsaturated fatty acid-enriched cells. It was assumed that fatty acids significantly affect the permeability and rigidity of the cell membrane, and that higher permeability and rigidity lead to increases in methanolysis activity and enzymatic stability, respectively. Next, to investigate the optimal composition of the mixture of oleic and palmitic acid added to the culture medium, two cycles of repeated batch operation were carried out using mixtures with varying ratios of oleic to palmitic acid. Figure 8.10 shows ME content after 2.5 h in the first batch cycle and the initial reaction rate of ME production in the second batch cycle as a percentage of that in the first. This value reflects the degree of enzymatic stability: the higher it is the greater the enzymatic activity that can be expected. Following increase in the fatty acid ratio, indicated by Rf [= oleic acid/(oleic acid + palmitic acid), w/w], there was no significant acceleration of the decrease in the initial reaction rate up to Rf value of 0.67, beyond which however it decreased rapidly. ME content showed its maximum value at Rf of 0.67, and decreased at Rf values greater or less than this critical level. It was thus concluded that there exists an optimal Rf value of 0.67 which yields both higher methanolysis activity and higher stability. Figure 8.11 shows the time course of ME content in repeated methanolysis using R. oryzae cells obtained at various Rf values. The figure shows that, at Rf value of 1.0, both ME content and the initial rate of ME production decreased sharply with each cycle to give an ME content of only 5 % at the end of ten batch cycles. In contrast, at Rf value of 0.83 and 0.67, ME production rates decreased gradually with each cycle, and, in the latter case in particular, ME content was maintained at a high value of around 55 % even after ten batch cycles. These results are consistent with the data in Figure 8.10 and indicate that the optimal value of Rf in terms of both ME content and ME production rate is around 0.67. Several studies have shown that free fatty acids affect the properties of the plasma membrane. Many have reported that membrane permeability is significantly affected by 20 15 10 5 Methyl ester content (wt.%)
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Biofuels Biofuels. Edited by Wim So
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Biofuels Edited by WIM SOETAERT Ghe
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Contents Series Preface ix Preface
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Contents vii 6.3 Biomass Gasificati
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Series Preface Renewable resources,
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Preface This volume on Biofuels fit
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Editors List of Contributors Wim So
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1 Biofuels in Perspective W. Soetae
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Table 1.1 Approximate average world
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Table 1.3 Energy yields of bio-ener
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Biofuels in Perspective 7 is burnt
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2 Sustainable Production of Cellulo
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Sustainable Production of Cellulosi
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Figure 2.9 2004 US adoption rates o
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3 Bio-Ethanol Development in the US
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Bio-Ethanol Development in the USA
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Biorefineries in Production (115) B
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Cost of Cellulosic Ethanol, $ per g
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4 Bio-Ethanol Development(s) in Bra
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Bio-Ethanol Development(s) in Brazi
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Share of energy consumption 100% 90
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Table 4.2 Main technological improv
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4.7.4 Use of Fertilizers and Pestic
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78 Biofuels Table 5.1 Biodiesel pro
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80 Biofuels CH 2 O CH O COR R1 + 3
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82 Biofuels short reaction times. 9
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84 Biofuels Table 5.4 Overview on h
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86 Biofuels Table 5.5 Critical cond
Page 103 and 104: 88 Biofuels methoxide as catalyst u
Page 105 and 106: 90 Biofuels KOH Methano Oil/Fat Aci
Page 107 and 108: 92 Biofuels 16. J. Graille, P. Loza
Page 110 and 111: 6 Bio-based Fischer-Tropsch Diesel
Page 112 and 113: 6.2.1.2 Catalysts Bio-based Fischer
Page 114 and 115: Bio-based Fischer-Tropsch Diesel Pr
Page 132 and 133: 7 Plant Oil Biofuel: Rationale, Pro
Page 134 and 135: Table 7.1 Market milestones for pla
Page 136 and 137: Water CO 2 Figure 7.1 Closed CO 2 l
Page 138 and 139: Plant Oil Biofuel: Rationale, Produ
Page 140 and 141: Plant Oil Biofuel: Rationale, Produ
Page 142: Plant Oil Biofuel: Rationale, Produ
Page 145 and 146: 130 Biofuels Among the attractive f
Page 147 and 148: 132 Biofuels Table 8.1 Enzymatic tr
Page 149 and 150: 134 Biofuels conversion was maintai
Page 151 and 152: 136 Biofuels (diglycerides) decreas
Page 153: 138 Biofuels ME content (wt.%) Reac
Page 157 and 158: 142 Biofuels (a) 34 kDa 31 kDa 34 k
Page 159 and 160: 144 Biofuels preparation of whole-c
Page 161 and 162: ability to reduce flocculation (% o
Page 163 and 164: 148 Biofuels 5. R. C. Strayer, J. A
Page 165 and 166: 150 Biofuels 46. H. Fukuda, Immobil
Page 168 and 169: 9 Production of Biodiesel from Wast
Page 170 and 171: Production of Biodiesel from Waste
Page 174 and 175: 9.3.2 Processing of Crude and Waste
Page 176 and 177: Heavy layer from alkaline neutralis
Page 182 and 183: CPO I 1 1 Heating 60°C Reaction st
Page 184 and 185: References Production of Biodiesel
Page 186 and 187: 10 Biomass Digestion to Methane in
Page 188 and 189: Cow manure Pig manure Yard manure B
Page 190 and 191: Number of plants 3000 2500 2000 150
Page 192 and 193: Biomass Digestion to Methane in Agr
Page 196 and 197: Table 10.4 Alternative forms of ene
Page 200 and 201: Wet fermentation 3 - 10% TS applica
Page 202 and 203: Rel. Frequency [%] 35 30 25 20 15 1
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Steam 2 1 Energy crops (& manure) D
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Biomass Digestion to Methane in Agr
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198 Biofuels 11.1 Introduction Hydr
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200 Biofuels lactate 6 glucose 1 GA
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Table 11.2 Continued Organism Domai
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204 Biofuels NADH is that the react
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206 Biofuels Clostridium thermocell
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208 Biofuels in particular in Cl. p
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210 Biofuels ferredoxin-dependent m
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212 Biofuels Concentration (mM) 45
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214 Biofuels genes of the glycolysi
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216 Biofuels 11. S. Tanisho and Y.
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218 Biofuels 49. M. J. Axley, D. A.
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220 Biofuels 83. P. J. Silva, E. C.
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12 Improving Sustainability of the
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Table 12.1 Corn ethanol dry mill: e
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Table 12.2 Atmospheric CO2 (equival
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Table 12.3 Incremental CO2 equivale
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Improving Sustainability of the Cor
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Improving Sustainability of the Cor
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Index italic entries indicate refer
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iorefineries 3, 10, 11, 41 and corn
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policy (official) 59-61 production
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NADH 200-6, 207, 210 natural gas 1
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Biofuels in Perspective

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