Biodiesel Production by Simultaneous Transesterification and Esterification

1
Biodiesel Production by Simultaneous
Transesterification and Esterification
Present at AIChE Meeting Nov. 20, 2008

• Shuli Yan, Manhoe Kim, Steve O. Salley, John
  Wilson, and K. Y. Simon Ng
• National Biofuels Energy Laboratory
• NextEnergy/Wayne State University
• Detroit, MI 48202

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Outline

• Introduction
• Experiment
• Results and Discussion
• Conclusion

• Biodiesel
• Traditional Processes for Biodiesel Production
• Literature Review

• Transesterification
• Esterification
• Hydrolysis
• Effects of FFA and Water
• Effect of Catalyst Structure

3
Introduction

• Biodiesel

• A mixture of fatty acid esters
• Derived from vegetable oils, animal fats, waste
  oils

4
Introduction

• Biodiesel - Advantages

• Biodegradable
• Low emission profile
• Low toxicity
• Efficiency
• High lubricity

5
Introduction

• Traditional 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

• Large amount of waste water
• Long time for phase separation
• High process cost

• Highly corrosive
• Long oil pretreatment process
• Long product purification process

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Introduction

• Decrease of Feedstock Cost
• Decrease of Process Cost

• Using unrefined or waste oils as feedstock
• Crude vegetable oils, recycled cooking oils,
  trap grease etc.

• Simplifying the pretreatment and reaction
  process
• Simultaneous catalysis of transesterification
  and esterification
• Simplifying the product purification process
• Replace homogeneous catalysts by heterogeneous
  catalysts

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Introduction

• Effects of FFA and water

Decrease
Decrease
Figure 1 Effects of FFA and water on traditional
processes
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Literatures

• ZnO
• ZnO, ZnO-Al2O3, I2/ZnO
• Contain base or acid sites
• Low activity and unstable, low tolerance to water
  and FFA
• La2O3
• La2O3/TiO2, La2O3-Ni/MgO
• Structure promoter, increase surface base site,
  thermal stability
• No reports in biodiesel production
• Mixed ZnO- La2O3 System
• Homogeneous Co-precipitation
• ZnLa 10 11 31 91 01

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Unrefined or waste oils
Transesterification Esterification
Hydrolysis
Figure 1 Reactions involved in the treatment of
crude oils using Zn3La1 catalyst.
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Objective

• Develop a new class of heterogeneous catalysts
• High tolerance to water and FFA
• Simultaneously catalyze transesterification and
  esterification, while minimizing hydrolysis
• Process crude oils directly

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Experiment

• Homogeneous Co-precipitation Method

1. Prepare mixture solutions of Zn(NO3)2 , La(NO3)3
   and urea in appropriate ratios
2. Heat to 100 oC and hold for 6 hr
3. Stirred with magnetic stirrer
4. Filter/unfilter
5. Dry at 150 oC for 8 hr
6. Use step-rise calcination method to control the
   catalyst morphology

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Experiment

• Reactor
• Product analysis

Parr 4575 HT/HP Reactor (500 ml, 500 C, 34 MP)

• Transesterification
• Esterification
• Hydrolysis

• GC-MS
• Karl Fischer (Water Content)
• Titration (Fatty Acid Content)

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Catalyst characterization

• XRD

ZnO, La2CO5 LaOOH
Figure 13 XRD patterns of zinc and lanthanum
mixed metal oxides
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Catalyst Characterization
Table 1 XRD Structures of Zinc and Lanthanum
Mixtures
Catalyst XRD structure Mean grain size of ZnO nm Lattice constants for ZnO phase Lattice constants for ZnO phase Lattice constants for ZnO phase Lattice constants for ZnO phase Zn La (bulk molar ratio )
Catalyst XRD structure Mean grain size of ZnO nm a Å c Å Vol Å3 Density Zn La (bulk molar ratio )
Zn10La0 ZnO gt100 3.25 5.21 47.63 5.68 10
Zn9La1 ZnO 27.6 3.25 5.36 48.62 5.56 8.9 1
Zn3La1 ZnO, La2CO5 LaOOH 17.1 3.25 5.23 47.81 5.65 3.5 1
Zn1La1 ZnO, La2CO5 LaOOH 9.8 3.33 5.10 49.12 5.50 1.2 1
Zn0La10 La2CO5 LaOOH / / / / / 01
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XPS
Table 2 XPS data of Zinc and Lanthanum Mixtures
Lewis Base Site
Lewis Acid Site
Total Basic and Acid Site
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Metal oxides in transesterification
Mixed oxide shows the highest activity
170 oC
Figure 1 Transesterification activities of
Zn10La0, Zn3La1 and Zn0La10 as a function of
temperature.
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Metal oxides in transesterification
Figure 2. Transesterification activities of
Zn10La0, Zn9La1, Zn3La1, Zn1La1 and Zn0La10 at
200 oC
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Metal oxides in transesterification
Figure 3 Effect of initial oil concentration on
transesterification.
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Metal oxides in transesterification
a 1.08
Eappl 91.28 KJ mol-1
Figure 4 Effect of reaction temperatures
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Metal oxides in esterification
140 oC
Figure 6 Esterification of oleic acid with
methanol as a function of reaction temperature
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Metal oxides in esterification
Figure 8 Process using refined oil with 5 FFA
addition
Figure 7 Yield of oleic methyl ester at 200 oC
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Metal oxides in hydrolysis
X
220 oC
Figure 8 Hydrolysis activities of Zn3La1 as a
function of temperature.
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Metal oxides in hydrolysis

• Oil containing 5.30 water and 94.70
  triglycerides

Figure 9 Water content changes during the process
using refined oil with 5 water addition
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Effect of FFA on biodiesel production
Decrease
Figure 10 Effect of FFA additions on
transesterification. a Yield of FAME in the
presence of different FFA addition b Effect of
FFA content on equilibrium yield of FAME
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Effect of water on biodiesel production
Decrease
Figure 10 Effect of water addition on
transesterification. a Yield of FAME in the
presence of different water addition b Effect
of water addition on equilibrium yield of FAME
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Using unrefined and waste oils
Figure 11 Using some unrefined or waste oils for
biodiesel production
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Catalyst Life

• In Continuous Reactor

• In Batch Reactor

the catalyst reused 17 times
the catalyst runs 32.5 days
Figure 4 Yield of FAME vs Reaction Times
Figure 5 Yield of FAME vs Reaction Times
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Conclusion

• A single-step method using unrefined oils and
  heterogeneous zinc and lanthanum mixed oxides
• Oil transesterification reaction and FFA
  esterification reaction
• Minimizing hydrolysis of oil and hydrolysis of
  biodiesel
• A temperature window, 170 220 oC
• A strong interaction between Zn and La species
• La acts as a diluent of the matrix, promoting ZnO
  particle distribution, increasing the surface
  basic and acid sites, and enhancing activity of
  transesterification and esterification

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Acknowledgement

• Financial support from the Department of Energy
  (DE12344458) and Michigans 21st Century Job Fund
  is gratefully acknowledged.