Biodiesel from Waste or Unrefined Oils Using Calcium Oxide-based

Catalysts

Shuli Yan, Manhoe Kim, Steve O. Salley and K. Y. Simon Ng

National Biofuels Energy LaboratoryNextEnergy/Wayne State University

Detroit, MI 48202

AICHe Meeting at Nov. 16 , 2008

Content• Introduction

– Biodiesel– Traditional Processes for Biodiesel Production– Literature Review

• Experiment• Results and Discussion

– Catalyst Activity– Catalyst Structure– Effect of Water and FFA in Oil Feedstock– Effect of H2O and CO2 in Air– Effect of Reaction Conditions– Transesterification Mechanism

• Conclusion

Introduction• Biodiesel

A mixture of fatty acid esters

Derived from vegetable oils, animal fats, waste oils

Introduction Biodiesel - Advantages

Biodegradable Low emission profile Low toxicity Efficiency High lubricity

0

50

100

150

200

250M

illio

n G

allo

ns

1 2 3 4 5 6 7 8

Year

U.S. Biodiesel Production

99 00 01 02 03 04 05 06

IntroductionTraditional Processes for Biodiesel Production Refined oils as feedstock (food-grade vegetable oils)

Homogeneous strong base or acid catalysts (NaOH, H2SO4)

FFA content is lower than 0.5 % (wt)

Water content is lower than 0.06% (wt)

High price

Highly corrosive

Long oil pretreatment process

Long product purification process

Large amount of waste water

Long time for phase separation

High process cost

Introduction

Decrease of Feedstock Cost

Decrease of Process Cost

• Using inexpensive oils as feedstock

• Crude vegetable oils, recycled cooking oils, trap grease etc.

• Simplifying the oil pretreatment process

• Simplifying the product purification process

o Replace homogeneous catalysts by heterogeneous catalysts

Solid Base Catalysts

Goal

Catalyst T Time(h) Conv.(%) Ref.

KNO3/Al2O3 65°C 7 87 1

ZnO 120°C 24 80 2

HT (Mg-Al) 180°C 1 92 3

SO42-/ZrO2 200°C 4 95.7 4

I2/Zn 65°C 24 96 5

Nafion acid resins 60°C 8 50 6

Solid Base Catalysts

Catalyst T Time(h) Conv.(%) Ref.

Nano-CaO Room temperature

6-24 95 10

CaO 65°C 24 93 11

CaO 65°C 3 60 12

CaO, Ca(OH)2, CaCO3

65°C 24 95.7 13

1. Catalytic activities much lower than NaOH.

2. Conducted at elevated temperature and pressure.

3. Low tolerant to water and FFA in feedstocks.

Research Goal

Develop an effective biodiesel process catalyst with high activity

Using solid catalysts to replace homogeneous NaOH

An improved property in tolerance to water and FFA

Using solid catalysts in food-grade, unrefined and waste oils.

Experiment• Oil Feedstock

Fatty Acid

Components

Food-grade Soybean Oil

(%)

Crude Soybean Oil

(%)

Crude Palm Oil

(%)

Waste Cooking Oil

(%)

C 14: 0 0 0.27 0.21 0

C 16: 0 11.07 13.05 41.92 11.58

C 16: 1 0.09 0.39 0.23 0.18

C 18: 0 3.62 4.17 3.85 4.26

C 18: 1 20.26 22.75 42.44 24.84

C 18: 2 57.60 52.78 11.30 53.55

C 18: 3 7.36 6.59 0.04 5.60

FFA Content 0.02 3.31 0.24 3.78

Water Content 0.02 0.27 0.04 0.06

1

Experiment• Catalyst Preparation Ca and La nitrate salts

transparent solution

Stirring for 3h at 60 oC

Placing for 48h at RM

Filter and Wash

Drying for 24h at 100 oC

Calcining for 8h at 750 oC

Activation

Ethanol 3 N Ammonia; CO2, 4 vol %, each hours

Ammonia-Carbon Dioxide

Precipitate Method

Experiment• Catalyst Characterization

Basic Property

Hammett indicator method;

Hammett indicator-benzene carboxylic acid titration method;

Specific surface area

Micromeritics model ASAP 2010 surface area analyzer (North Huntingdon, PA)

TG/DTG

Perkin Elmer Pyris-1 (Waltham, MA)

XRD

Rigaku RU2000 rotating anode powder diffractometer (Woodlands, TX)

FTIR

Perkin Elmer Spectrum 400 spectrometer (Waltham, MA)

Experiments

• Transesterification

• Product analysis

10.0 g of soybean oil and 7.6 g of methanol and 0.5 g activated catalyst

GC-MS

Karl Fischer (Water Content)

titration (Fatty Acid Content)

Catalyst Activity

0 20 40 60 80 100 1200

20

40

60

80

100

Yie

ld o

f FA

ME

%

Time min

NaOH H2SO

4 Ca3La1 Ca1La0 Ca0La1

Figure 1 Transesterification activities of Ca3La1, Ca1La0, Ca0La1, NaOH, and H2SO4 at 64.5 oC and 1 atm.

Catalyst Structure• XRD

20 30 40 50 60 70 80

4

3

2

2 T heta

1

Figure 2 XRD spectra of Ca3La1 (curve 1), fresh Ca3La1 (curve 2), Ca0La1 (curve 3) and the Ca3La1 exposed to air for 30 days (curve 4).

Catalyst StructureTable 3 Specific surface areas, XRD, basicity and catalytic activity of

Ca1La0, Ca0La1, Ca3La1 and the Ca3La1 adsorbed water (Ca3La1-water) and Ca3La1 adsorbed FFA (Ca3La1-FFA).

Basicity mmol/g Catalyst Specific Surface

Area m2/g

X-ray Structure

4.2<H-

<6.8

6.8<H-

<7.2

7.2<H-

<9.8

9.8<H-

<15

Total Basicity

mmol/g

Yield of

FAME % 1

Ca1La0 10.4 CaO, CaCO3,

Ca(OH)2

0.3 0.1 \ \ 0.4 18.7

Ca0La1 9.9 La2CO5, LaOOH 0.1 \ \ \ 0.1 3.2

Ca3La1 62.6 CaCO3, Ca(OH)2,

La2CO5, LaOOH

0.6 2.0 10.4 1.0 14.0 95.3

Ca3La1-

water 2

\ \ 0.1 6.0 4.6 0.8 15.4 96.1

Ca3La1-

FFA 3

\ \ 0.1 \ \ \ 0.1 47.5

1

Catalyst Structure• FTIR

4500 4000 3500 3000 2500 2000 1500 1000 500

Frequence cm -1

1

2

3

Figure 3 FTIR analysis of Ca3La1 (1), Ca3La1 adsorbed water (2) and Ca3La1 adsorbed FFA (3)

Effect of Water and FFA in Oil Feedstock

0 20 40 60 80 100 120 140 1600

20

40

60

80

100

0 1 % 2 % 4 % 10 %

FA

ME

Yie

ld

%

Time min

Water addition

0 1 2 3 4 5 6 7 8 9 10 110

20

40

60

80

100

NaOH

H2SO

4

Ca3La1Yie

ld o

f FA

ME

%

Water content %

Figure 4 Effect of water addition on transesterification..

a b

Effect of Water and FFA in Oil Feedstock

0 20 40 60 80 100 1200

20

40

60

80

100

0 0.5 1.1 1.6 3.6 5.1 7.0F

AM

E Y

ield

%

Time min

FFA Addition %

Figure 5 Yield of FAME in the presence of different FFA addition.

Single Step Conversion of Unrefined and Waste Oil

Figure 6 Yield of FAME using unrefined and waste oils (a) and diluted unrefined oils (b).

0 20 40 60 80 100 120 140 160 180 2000

20

40

60

80

100

Yie

ld o

f FA

ME

%

Time min

Food-grade Soybean Oil

Crude Soybean Oil

Crude Palm Oil

Waste Cooking Oil

0 20 40 60 80 100 1200

20

40

60

80

100

Food-grade Soybean Oil

Diluted Crude Soybean Oil

Diluted Crude Palm Oil

Diluted Waste Cooking Oil

Yie

ld o

f FA

ME

%

Time min

a b

Effect of Water and FFA on Catalyst Structure

• Basic Property

• FTIR

Effect of H2O and CO2 in Air 1

Storage conditions Pretreatment conditions Total Basicity mmol/g Yield of FAME 1 %

Air for 12 hr \ 1.5 34.5

Air for 12 hr 200 oC, N2, 1.5 hr 1.5 38.3

Air for 12 hr 430 oC, N2, 1.5 hr 3.1 51.4

Air for 12 hr 750 oC, N2, 1.5 hr 14.2 97.2

Air for 12 hr 950 oC, N2, 1.5 hr 13.1 89.0

N2 flow with 10 (vol) % CO2, 4 (vol) % H2O \ 1.5 23.9

N2 flow with 10 (vol) % CO2, 4 (vol) % H2O 750 oC, N2, 1.5 hr 14.0 96.8

Table 4 Effects of storage and pretreatment conditions on the catalytic activity of Ca3La1.

Effect of H2O and CO2 on Catalyst Structure

• XRD

• FTIR

4500 4000 3500 3000 2500 2000 1500 1000 500

5

4

Wavenumber cm-1

1

2

3

Figure 7 FTIR spectra of Ca3La1 exposed to air about 3 min (1), 5 min (2), 8 min (3), 15 min (4) and 30 min (5).

Effect of H2O and CO2 on Catalyst Structure

• TG/DTG

200 400 600 800

TG Curve

DTG Curve

Temperature oC

8 %

16 %

Figure 8 TG/DTG curves of Ca3La1 exposed to air for 12 hours.

Effect of Reaction Conditions

0 20 40 60 80 100 120 140 160 180 2000

10

20

30

40

50

60

70

80

90

100

Yie

ld o

f FA

ME

%

Time min

6 10 15 20 24

Molar ratio of methanol to oil

Figure 9 FAME yields with different mass ratio of catalyst to oil (a), with different mole ratio of methanol to oil (b), and

with different reaction temperatures (c).

Effect of Reaction Conditions

Figure 9 FAME yields with different mass ratio of catalyst to oil (a), with different mole ratio of methanol to oil (b), and

with different reaction temperatures (c).

0 100 200 300 400 5000

20

40

60

80

100

Yie

ld o

f FA

ME

%

Time min

35 oC

45 oC

50 oC

58 oC

Transesterification Mechanism• Adsorption Sites

4500 4000 3500 3000 2500 2000 1500 1000 500

c

b

Frequence cm-1

a

1162

1097 718

Figure 10 FTIR spectra; (a) Ca3La1 adsorbed triglyceride (curve 1), free triglyceride (curve 2) and the fresh Ca3La1 (curve 3);

Transesterification Mechanism• Adsorption Sites

4500 4000 3500 3000 2500 2000 1500 1000 500

Frequence cm -1

1

2

3

12181365

1735

Figure 10 FTIR spectra; (b) free methanol (curve 1), the Ca3La1 adsorbed methanol (curve 2) and the fresh Ca3La1 (curve 3).

CH3

O

H

CH3OH

O H -/O 2- O H -/O 2-

CH3

O-

O H -/O 2-

H

O H -/O 2-

CH3

-O

C

OR1

O

R2

H

C a 2+ /L a 3+ C a 2+ /L a 3+

C

O

R1OR2O

R1OR2 +

C a 2+ /L a 3+

CH3

O

C

OR1

O

R2

-

CH3

O

C

OR1

R2 O -

O H -/O 2-

H

O H -/O 2-

H

O R2

O H -/O 2-

R2 OH

+ +

+

R1: alkyl group of fatty acidR2: alkyl esters of triglyceride

Figure 11 Schematic representation of possible mechanism for transesterification of triglyceride with methanol.

Conclusion

• A single-step method using unrefined oils and calcium and lanthanum mixed oxides

• strong base strength, large amount of basicity and high surface area

• A strong interaction between Ca and La species

• Highly tolerant to water and FFA in oil feedstock

Acknowledgement

Financial support of this research by the Department

of Energy (DE12344458) and Michigan's 21st

Century Job Fund program is gratefully

acknowledged

Thanks!