November 22, 2006 (9:30-9:45) The 2nd Joint International Conference on Sustainable Energy and Development (SEE2006) Bangkok, Thailand NEDO Biodiesel Production Process by Supercritical Methanol Technologies Shiro Saka Graduate School of Energy Science Kyoto University Kyoto, Japan
BDF Activity in Kyoto 220 garbage trucks(b100) (1.3 million liters/yr) 80 municipal busses (B20) (0.2 million liters/yr)
Biodiesel Production Plant in Kyoto City Method : Alkali-catalyzed Feedstock : Waste oils/fats (from household sector) Productivity : 5,000 L/day Waste Oil/fat Removal of water Alkali/MeOH MeOH Water Removal of water Additives BIODIESEL Heat Heat Glycerol Heat Heat Waste water Feedstock Pre-treatment Reaction Separation Post-treatment Product
Alkali-catalyzed Method for Commercial Biodiesel Production Transesterification CH 2 OCOR 1 CH OCOR 2 CH 2 OCOR 3 + 3CH 3 OH Alkaline catalyst R 1 COOCH 3 R 2 COOCH 3 R 3 COOCH 3 + CH 2 OH CH OH CH 2 OH Triglyceride Biodiesel Saponification R 4 COOH + KOH R 4 COOK + H 2 O Free fatty acid Alkaline catalyst Saponified product
Supercritical Fluid A pure substance may be changed into 3 phases such as gas, liquid and solid. Among these, the critical point exists between the gas and liquid. Above the critical point, there exists the high-density fluid which cannot be condensed any more, even if temperature and/or pressure are increased. Such a substance is called supercritical fluid. Pressure Critical Pressure Solid Liquid Triple Point Gas Temperature Supercritical Fluid Critical Point Critical Temp. Temperature-Pressure Relation of the Pure Substance H 2 O Critical Point: 374, 22.1MPa MeOH Critical Point: 239, 8.09MPa Under SC condition, Ionic Products: Increased (H 2 O Hydrolysis) (MeOH Methanolysis) Dielectric Constant: Decreased (Hydrophilic Hydrophobic)
Phase Changes in a Vicinity of Critical Point in MeOH Pressure (MPa) 24 23 22 21 20 Liquid MeOH SC MeOH B C A C.P. Gas MeOH 19 368 370 372 374 376 Temperature ( )
One-Step SC MeOH Method (Saka Process) MeOH recovery MeOH Oils/fats SC MeOH Separation (350 o C/20MPa) Biodiesel (BDF) Glycerol CH 2 -OCOR 1 CH-OCOR 2 + 3CH 3 OH CH 2 -OCOR 3 Triglyceride Transesterification No catalyst Esterification R 1 COOCH 3 CH 2 -OH R 2 COOCH 3 R 3 COOCH 3 + CH-OH CH 2 -OH Biodiesel R 4 COOH + CH 3 OH R 4 COOCH 3 + H 2 O Free fatty acid No catalyst Biodiesel
Thermal Stability of Methyl Linolenate in SC MeOH - : Untreated - : Treated 270 o C/20min (Two-step) 350 o C/9min (One-step) ester (C=O) alkyl (C-H) ester (C-O) trans (C=C) cis (C=C) ester (C=O) alkyl (C-H) cis ester (C=C) (C-O) trans (C=C) 2000 1800 1600 1400 1200 1000 800 600 Wave number (cm -1 ) 2000 1800 1600 1400 1200 1000 800 600 Wave number (cm -1 )
Isomerization of poly-unsaturated fatty acid methyl esters Cis- Methyl linolenate O O Supercritical Methanol (350 o C/9min) Trans- Methyl linolenate O O Cis- T m = - 10 partly Trans- T m = 30 An increase in melting point Deterioration in cold flow properties (?)
CH 2 OCOR 1 CH OCOR 2 CH 2 OCOR 3 Triglyceride Two-Step SCMeOH Method Water Oils/fats + (Saka-Dadan Process) Sub-C Water (270 o C/7MPa) MeOH Oil layer Water layer Step I: Hydrolysis 3H 2 O Step II: Esterification MeOH recovery SC MeOH (270 o C/7MPa) R 1 COOH R 2 COOH R 3 COOH Fatty acids Waste water Glycerol R 4 COOH + CH 3 OH R 4 COOCH 3 + H 2 O Fatty acid Biodiesel + Purification Biodiesel (BDF) CH 2 OH CH OH CH 2 OH
Arrhenius Plots for Transesterification, Hydrolysis and Esterification of Rapeseed Oil Reaction rate constant (1/sec) 10-1 350 300 250 200 ( o C) T c (Water) T c (MeOH) 10-2 10-3 Hydrolysis 270 o C Transesterification Esterification 10-4 1.4 1.6 1.8 2.0 2.2 Temperature (1000/K)
Direct Observation through Sapphire Window MeOH Oil Water Oil 240 280 340 280 300 340 Transesterification 2 Phase 1 Phase (Low Temp) (High Temp) Hydrolysis 2 Phase 2 Phase (Low Temp) (High Temp) MeOH + Fatty Acid 160 260 340 Esterification 1 Phase 1 Phase (Low Temp) (High Temp)
Two-Step Biodiesel Production Process (Hydrolysis Esterification Re-esterification) Methanol Distillation Methanol/ Water Oils Water Hydrolysis Esterification Distillation Hi Pres. Pump Phase Separation Methanol Re-Esterification BDF Oil Phase (Fatty Acids) Water Phase (Glycerin) Step II: Esterification R 4 COOH + CH 3 OH R 4 COOCH 3 + H 2 O Fatty acid Biodiesel
Reactions Involved in SC MeOH Methods Oils/fats Triglycerides Fatty acids Transesterification Hydrolysis Fatty acids Esterification One-Step (Saka) Two-Step (Saka-Dadan) Methyl esters (BDF)
Effect of Free Fatty Acid on Transesterification/ Esterification by Various Methods Methyl esters (%) 100 80 60 40 20 Alkali-catalyzed 0 0 10 20 30 Free fatty acid (%) SC MeOH Lipase-catalyzed Ion-Ex-catalyzed Acid-catalyzed
Effect of Water on Transesterification/Esterification by Various Methods Methyl esters (%) 100 80 60 40 Alkali-catalyzed Acid-catalyzed 20 Lipase-catalyzed Ion-ex-catalyzed 0 0 5 10 15 20 25 Water (%) SC MeOH
Applicable Range of Different Methods in Water and Free Fatty Acid Contents in Various Oils/Fats 100 Lipase-catalyzed Ion-ex-catalyzed SC MeOH Fatty acids (wt%) 10 Dark oil Waste oil Acid-catalyzed Used frying oil Waste palm oil Virgin oil Alkali-catalyzed 1 1 10 100 Water (wt%)
Specification Standards of Biodiesel Fuel Unit Kyoto EU US Density (15 o C) g/ml 0.86 ~ 0.90 0.86 ~ 0.90 0.88 Viscosity (40 o C) mm 2 /s 3.5 ~ 5.0 3.5 ~ 5.0 1.9 ~ 6.0 Pour point o C < 7.5 - - CFPP o C < 5 - - Carbon residue (10%) % < 0.30 < 0.30 < 0.50 (100%) Cetane number > 51 > 51 > 47 Water ppm < 500 < 500 < 500 Flash point o C > 100 > 101 > 130 MG % < 0.8 < 0.8 - DG % < 0.2 < 0.2 - TG % < 0.2 < 0.2 - G % < 0.02 < 0.02 < 0.02 Total glycerol % < 0.25 < 0.25 < 0.24 Methanol % < 0.2 < 0.2 - Na+K mg/kg < 5 < 5 - Acidic value < 0.5 < 0.5 - Iodine value < 120 < 120 -
Thank you for your attention! Kyoto University 21 COE Program Grant-in-Aid for Scientific Research (B)(2) NEDO for High Efficiency Bioenergy Conv Projects