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Catalyst-free biodiesel reactions and post treatment using commercial polymeric resins
Sipho C. Ndlela, Norman K. Olson
Iowa Energy Center, Iowa State University, BECON Facility, 1521 West F Avenue, Nevada, IA 50201, USA
INTRODUCTION
Materials:
• RBD Soybean oil
• Oleic Acid (100% FFA)
• Crude corn oil (16% FFA)
• Restaurant grease (10% FFA)
• Methanol
Reactor conditions:
• 1 Liter Batch reactor, 200 to 350 oC
• Molar ratios of methanol to oil: 6 to 80 (Molar ratio)
Analysis:
• Titration using 0.1 N KOH (FFA analysis)
• ASTM D 6584 biodiesel GC method
Post treatment methods:
• Amberlite BD10 DRY (10% and 25%)
• HERMLE Z200 A centrifuge 6000 RPM, 15 minutes
%Conversion
97
96
94
94
94
93
70
92
60
50
90
40
88
Reaction conversion
86
20
84
91
90
6
27
54
Molar ratio, MeOH/Oil
82
Fig.3 Soy biodiesel conversion rates at 300oC and increasing molar ratio,
analyzed using a Varian CP 3800 GC-FID
100
49
95
90
Reaction temperature,C
47
Reaction pressure,MPa
45
10
82
300
310
41
80
39
75
37
300
310
320
330
340
350
35
360
340
14
12.98
% water from reaction
12
9.92
10
14
8
85
320
330
Temperature, C
0
350
Fig.6 Oleic Acid esterification at 8 Molar ratio
7.91
9.92
10
7.91
8
6
12.98
% water from…
12
43
70
290
30
Reaction pressure-MPa
92
% Conversion
MATERIALS & METHODS
98
98
95
94
99
99
% Conversion
Biodiesel was synthesized under catalyst-free supercritical
methanol reactions using a variety of oils at 250 to 325oC in a 1liter high-pressure batch reactor. Multiple experiments were
performed at 6 to 80 molar ratios of methanol to oil; product
samples were then analyzed by titration, and a Gas
Chromatograph which monitored conversion of triglyceride by
measuring total glycerine. At 300oC and 27 molar ratios, 97%
conversion was attained. Following the experiment samples were
placed in separatory funnel and the crude biodiesel layer was
treated further to remove free glycerine by centrifugation and also
with an Amberlite BD10dry which was more effective.
100
6
4
4
2
0.09
0.13
O.A
MeOH
0
2
0
0.09
0.13
O.A
MeOH
300C
300C
325C
350C
325C
350C
Fig.7 Reaction water during oleic acid esterification reaction
Temperature, C
Bottom product
Fig.4 Soy biodiesel transesterification: Temperature effect at 27 Molar ratio,
analyzed using a Varian CP 3800 GC-FID
Recovered product
97
97
96
Glycerine after reaction
Post treatment
0.80
High Pressure
Batch Reactor
system
92
0.70
92
91
Fig.1 Image from left to right: RBD soybean
oil, crude corn oil, restaurant grease
% Free Glycerine
0.60
0.50
0.40
A
0.30
•Top layer: Mostly methanol, 7 wt%
methyl esters and glycerine
•Bottom layer: About 90 % Crude
biodiesel, glycerine, methanol
Fig. 2 Crude soy biodiesel sample taken after
reaction at 300oC, 8000 psi, 6 Molar ratio
C
0.10
Fig.5 Effect of adding a modifier: A: Methanol added at 25oC , B: Methanol
added at 300 oC, C: Methanol and CO2 added at 300 oC.
0.00
Esterifation results at high temperature and pressure
0.20
Centrifuge
Two phases separated:
B
BD10dry, 10%
BD10dry, 25%
Fig.5 Crude biodiesel post treatment using a HERMLE Z200 A centrifuge and
Amberlite BD10 DRY
Soybean Oil transesterifcation Results
• Transesterification reaction at high temperature, pressure
and variable molar ratio resulted to two distinct phase after
separation.
• At 27 Molar ratio, 325oC and 5500 psi, conversion dropped to
73%
• Amberlite BD10dry was more effective in reducing free
glycerine compared to centrifugation
• Oleic acid esterification conversion rates decreased (91 to 83%) from 300
to 350 oC, due to accumulation of reaction water.
• Direct esterification at 300 oC and 8 Molar ratio, on oleic acid, restaurant
grease, crude corn oil resulted into methyl esters at varying conversion
rates. Two layers separated with the top consisting of water, methanol and
about & 5 wt% crude biodiesel, whereas the bottom layer was about 90%
methyl esters methanol and water.
• There was no effect on conversion rates when adding a modifier and/or
pumping methanol at 300 oC compared to simultaneously adding oil and
methanol at 25 oC
ACKNOWLEDGMENTS
Iowa Energy Center and DOE Fund: DE-FG36-06GO86014