Master of Science Thesis

KTH School of Industrial Engineering and Management

Energy Technology EGI-2016-016MSC EKV1129

Division of Applied Heat and Power Technology (EKV)

SE-100 44 STOCKHOLM

Biodiesel Production from Jatropha and

Waste Cooking Oils in Mozambique

Dalila Augusto Mussengue San

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Master of Science Thesis EGI-2016-016MSC

EKV1129

Biodiesel Production from Jatropha

and Waste Cooking Oils

in Mozambique

Dalila Augusto Mussengue San

Approved

2017-09-13

Examiner

Miroslav Petrov (KTH)

Supervisor

Angelica Hull (KTH)

João Chidamoio (UEM)

Commissioner

University Eduardo Mondlane,

Maputo

Contact person

Dr. Carlos Lucas (UEM)

Dr. Geraldo Nhumaio (UEM)

ABSTRACT

In Mozambique, as in the rest of the world, the fast population growth and industrial development leads to increasing energy consumption. A valuable new source of energy relevant to Mozambique is biodiesel produced from jatropha seed oil and from waste cooking oils. This thesis project investigates the production steps of biodiesel from these feedstocks in laboratory environment. Local biodiesel production could not alone be the solution to the problem of finding alternative fuels to firewood, charcoal and fossil fuels, but could effectively be produced from jatropha oil and waste cooking oil in small scales, thus avoiding pollution of land and water and decreasing deforestation together with providing self-sufficiency and energy independence.

In addition, there are also advantages in economic terms, since the used cooking oil, although considered waste, acquires economic value and creates new jobs, and reduces the generally heavy dependence of Mozambique on the import of foreign fuels.

The biodiesel produced can be used by vehicles with diesel engines or to power lights and stoves, especially in suburban and rural areas.

Keywords: Jatropha, Waste Cooking Oil, Transesterification Process, FAME, Biodiesel.

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DEDICATION

To my husband and my children who helped me and had patience throughout my thesis journey.

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ACKNOWLEDGEMENTS

I would like to thank my supervisor Professor Angelica Hull for the guidance she gave me when

planning and writing this thesis.

I would also like to express my gratitude to my local supervisors Engº João Chidamoio first and

then Dr. Geraldo Nhumaio for their effort in helping me during the elaboration of this thesis.

My thanks go to Dr. Carlos Lucas for facilitating and Andrew Martin for coordinating the course

“Sustainable Energy Engineering”, under which I developed this thesis.

I thank everyone who directly or indirectly has been involved in this work, specially to my family

for their patience and support during the course.

Finally I would like to thank God for strengthening me throughout the masters program.

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ABBREVIATIONS AND ACRONYMS

B100 : 100% Biodiesel

CO : Carbon Monoxide

CO2 : Carbon Dioxide

DG : Diglyceride

HC : Hydrocarbon

FA : Fatty Acid

FAME : Fatty Acid Methyl Esters

FUNAE : National Energy Fund

KOH : Potassium Hydroxide

KTH : Royal Institute of Technology

KFC : Kentucky Fried Chicken

Lab : Laboratory Test

MG : Monoglyceride

NaOH : Sodium Hydroxide

PM : Particulate Matter

R : Alkyl group

RET : Renewable Energy Technology

SVO : Straight Vegetable Oils

TG : Triglyceride

WCO : Waste Cooking Oil

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LIST OF FIGURES

Figure 2.1 Transesterification reaction

Figure 2.2 Transesterification reaction stepwise

Figure 2.3 Biodiesel production scheme diagram

Figure 3.1 Jatropha oil

Figure 3.2 Jatropha seed with peel

Figure 3.3 Jatropha seed peeled

Figure 3.4 Press machine

Figure 3.5 Methanol

Figure 3.6 Potassium Hidroxide (KOH)

Figure 3.7 Transesterification reaction

Figure 3.8 Reaction mixture in a separating funnel.

Figure 3.9 Glycerine.

Figure 3-10 The upper layer of the reation mixture

Figure 3-11 Ethyl Acetate

Figure 3-12 Solution first wash (ethyl acetate+upper layer)

Figure 3.13 Solution second wash (ethyl acetate+upper layer)

Figure 3.14 Solution third wash (ethyl acetate+upper layer)

Figure 3.15 Calcium chloride filtration

Figure 3.16 Beginning of distillation process (organic layer purified)

Figure 3.17 End of distillation process (yellow oily product separated from ethyl acetate)

Figure 3.18 Methyl esters

Figure 3.19 AN determination

Figure 3.20 pH measurement

Figure 3.21 Transesterification reaction

Figure 3.22 Transesterification reaction

Figure 3.23 Separating funnel (reaction mixture+glycerine fraction)

Figure 3.24 Reaction mixture after separation

Figure 3.25 Glycerine

Figure 3.26 Separating funnel (reaction mixture+glycerine fraction)

Figure 3.27 Purification process using a sorbent

Figure 3.28 Fatty Acid Methyl Esters

Figure 3.29 Transesterification reaction

Figure 3.30 Separating funnel (mixture+glycerine)

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Figure 3.31 Glycerine

Figure 3.32 Reaction mixture and the remaining KOH & methanol

Figure 3.33 Separation of glycerine phase

Figure 3.34 Glycerine

Figure 3.35 Methyl esters

Figure 3.36 Silica gel

Figure 3.37 Methyl esters purification process

Figure 3.38 Methyl esters obtained after filtration

Figure 3.39 Transesterification reaction

Figure 3.40 Separation of glycerine phase

Figure 3.41 Mixture obtained after separation

Figure 3.42 Reaction mixture with the remaining solution

Figure 3.43 Whitening clay

Figure 3.44 Methyl esters purification process

Figure 3.45 Methyl esters obtained after filtration

Figure 4.1 Expected pH value vs. laboratory results graph

Figure 4.2 Expected AN value vs. laboratory AN graph

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LIST OF TABLES

Table 2.1 Specifications for Biodiesel (B100), ASTM D 6751-08 Method

Table 2.2 Specifications for Biodiesel (B100), EN 14214-03 Method

Table 2.3 Biodiesel Production and Capacity

Table 3.1 Laboratory test data summary

Table 3.2 Laboratory test results

Table 3.3 pH of the methyl esters

Table 3.4 AN of the methyl esters

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TABLE OF CONTENTS

1 INTRODUCTION .......................................................................................................................... 10

1.1 OBJECTIVES ........................................................................................................................... 11

1.1.1 General Objective ............................................................................................................... 11

1.1.2 Specific Objectives .............................................................................................................. 11

1.2 METHODOLOGY .................................................................................................................. 11

1.3 SCOPE ..................................................................................................................................... 11

2 LITERATURE REVIEW ................................................................................................................ 12

2.1 WHAT IS BIODIESEL ............................................................................................................ 12

2.2 ADVANTAGES AND DISADVANTAGES OF USING BIODIESEL ................................. 15

2.3 THE TRANSESTERIFICATION PROCESS .......................................................................... 17

2.4 TRANSESTERIFICATION METHODS THAT HAVE BEEN USED FOR CONVERTING

USED COOKING OIL INTO BIODIESEL ................................................................................... 19

3 BIODIESEL PRODUCTION ........................................................................................................ 23

3.1 OBTAINING METHYL ESTERS FROM JATROPHA OIL .................................................. 23

3.2 OBTAINING FATTY ACID METHYL ESTERS FROM VEGETABLE OILS .................... 40

4 RESULTS AND DISCUSSION ...................................................................................................... 69

5 CONCLUSIONS ............................................................................................................................. 70

6 RECOMMENDATIONS ................................................................................................................ 71

7 REFERENCES ............................................................................................................................... 73

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1 INTRODUCTION

In 1911 Dr. Rudolf Diesel wrote, “The diesel engine can be fed with vegetable oils and would help

considerably in the development of the agriculture of the countries which will use it” He

demonstrated the use of a variety of vegetable oils, and more have been tried since.

Vegetable oils occur naturally in the seeds of many plants and can be extracted by crushing and

pressing. Their energy content is typically around 36-39 GJ t-1 and is only a little less than that of

fossil diesel fuel (about 42 GJ t-1). [1]

Vegetable oils could be burned directly in diesel engines, as Raw Straight Vegetable Oils (SVO),

where the only treatment is filtering, however, the use of SVO in burners or engines is difficult due

to high viscosity, danger of polymerization, wax sedimentation, coking at fuel injectors,

solidification at low temperatures, etc. Engine conversion or tuning is necessary if SVO is the fuel.

They can also be blended with diesel fuel, but incomplete combustion coudl be a major problem,

leading to carbon build-up in the cylinders. Due to these facts, chemical conversion of the vegetable

oils into esters, a type of biodiesel, is preferred. [2]

Biodiesel solves some SVO-related problems by having physical properties very similar to those of

fossil diesel, however certain major problems remain, plus that the presence of methanol and alkali

residues in biodiesel might also be a challenge for engines not adapted to the fuel. [2]

The importance of biodiesel production from jatropha and waste cooking oil in Mozambique is to

reduce the balance sheet for importing fossil fuels, to contribute to the diversification of energy

sources, to promote rural development with jatropha production, to contribute to the reduction of

emissions of greenhouse gases, to reduce the disposal of waste cooking oil in the domestic sewage,

landfills, water and soil and to promote the renewable energies. [3]

The impact of biodiesel production in Mozambique is to reduce the fuel prices, to increase the

agricultural production and productivity, to increase the income of rural communities, to reduce

the pollution levels in the atmosphere, water and soil, thus improving the environmental

conditions and consequently the public health, to value the waste cooking oil economically, to

create new jobs, to serve as fuel for stoves, to fuel vehicles with diesel engines and to increase

the lighting in suburban and rural areas. [4]

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1.1 OBJECTIVES

1.1.1 General Objective

This research work has as main objective biodiesel production from jatropha and waste

cooking oil. For this purpose, the following specific objectives were outlined:

1.1.2 Specific Objectives

To study the best way to produce biodiesel from jatropha oil.

To study the best way to produce biodiesel from waste cooking oil.

Study the possibility of biodiesel large-scale production in Mozambique.

1.2 METHODOLOGY

This study followed a work methodology that included the following steps:

Literature review;

Laboratory scale production of biodiesel from jatropha oil;

Laboratory scale production of biodiesel from used cooking oil;

Analysis and discussion of the results achieved;

Conclusions.

1.3 SCOPE

The present report is divided into 6 chapters, where the chapter 1 contains the introduction,

the objectives and the methodology used in this work. The chapter 2 is dedicated to literature

review. Chapter 3 describes the various methods of biodiesel production. Chapter 4 presents

the results. The chapter 5 is reserved for conclusion and finally the chapter 6 gives some

recommendations about the work. At the end, the report presents some references.

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2 LITERATURE REVIEW

2.1 WHAT IS BIODIESEL

Biodiesel is a mixture of fatty acid esters commonly produced through the chemical reaction of

transesterification. The transesterification process involves the reaction of triglyceride (oil or fat)

with an alcohol in the presence of a catalyst, usually a strong base such as sodium or potassium

hydroxide. The alcohol reacts with the fatty acids forming the mono-allkyl ester called biodiesel

and glycerol. [5] Methanol or ethanol are commonly used alcohols in the process. Methanol

produces methyl esters, commonly referred to as Fatty Acid Methyl Ester-FAME, and ethanol

peoduces ethyl esters, commonly referred to as Fatty Acid Ethyl Ester-FAEE. [1] At the final stage

of the process the glycerol is removed and the excess alcohol extracted for recycling, leaving the

biodiesel. The glycerol is a valuable by-product and can be sold as is. Purified glycerol is traditionally

utilized as a resource for the pharmaceutical and cosmetical industries, but could also be used

directly as fuel or in fuel blends.

Biodiesel can be used as a heating oil in domestic and commercial boilers. Recently, biodiesel has

attracted enormous attention from the transport industry all over the world as an alternative fuel

for diesel engines because of its renewability. Biodiesel can be produced from renewable sources

such as vegetable oil, animal fat and used cooking oil. [2]

Carrently biodiesel is used in standard diesel engines at low blends with conventional diesel, up to

20%, and in modified diesel engines at higher blends, including neat fuel at a 100 % blend.

Commercial grades are represented by a number following a B letter. For example, B5 is 5 percent

biodiesel with 95 percent petroleum, B20 is 20 percent biodiesel with 80 percent petroleum, or

B100 is 100 percent biodiesel without any petroleum content. [6]

The tables below show the biodiesel specification used in Mozambique:

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Table 2.1 Specifications for Biodiesel (B100), Methods ASTM D 6751-08 [7]

Property Test Method Specification Limits

Acid Number ASTM D 664 0.50 maximum mgKOH/g

Calcium and Magnesium EN 14538 5 ppm maximum

Carbon Residue ASTM D 4530 0.050 maximum Wt %

Cetane Number Cetane Number ASTM D

613

47 min

Cloud Point ASTM D 2500 Report in °C

Cold Soak Filterability ASTM Annex A1 360 maxF Seconds

Copper Strip Corrosion ASTM D 130 No. 3 maximum

Distillation-Atmospheric

Equivalent Temperature

90% Recovery

ASTM D 1160 360 maximum °C

Flash Point ASTM D 93 130 minimum °C

Glycerin – Free ASTM D 6584 0.020 maximum Wt %

Glycerin – Total ASTM D 6584 0.240 maximum Wt %

Kinematic Viscosity - 40°C ASTM D 445 1.9 – 6.0 mm 2/s

Methanol Content EN 14110 0.20 maximum Wt %

Oxidation Stability EN 14112 3 hours minimum

Phosphorus Content ASTM D 4951 0.001 Wt % or 10 ppm

Sodium and Potassium EN 14538 5.00 ppm maximum

Sulfated Ash ASTM D 874 0.020 maximum Wt %

Sulfur (S15) ASTM D 5453 15.0 ppm maximum

Sulfur (S500) ASTM D 5453 500 ppm maximum

Water and Sediment ASTM D 2709 0.050 maximum Vol. %

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Table 2.2 Specifications for Biodiesel (B100), EN 14214 – 03 Method [8]

Property Method Specification Limits

Acid Number EN 14104 0.50 mgKOH/g maximum

Carbon residue (10%) EN ISO 10370 0.30 %(m/m) maximum

Cetane Number EN ISO 5165 51.0 minimum

Copper Strip Corrosion

(3hr @ 50°C)

EN ISO 2160 Class 1 rating

Density @ 15°C EN ISO 3675,

EN ISO 12185

860-900 kg/m3

Ester Content EN 14103 96.5 %(m/m) minimum

Flash Point ISO/ CD 3679 Above 101°C minimum

Glycerol – Free EN 14105, EN 14106 0.02 %(m/m) maximum

Glycerol – Total EN 14105 0.25 %(m/m) maximum

Monoglyceride Content EN 14105 0.80 %(m/m) maximum

Diglyceride Content EN 14105 0.20 %(m/m) maximum

Triglyceride Content EN 14105 0.20 %(m/m) maximum

Iodine Value EN 14111 120 maximum

Linolenic acid methyl EN 14103 12 %(m/m) maximum

Methanol Content EN 14110 0.20 %(m/m) maximum

Oxidation Stability @110°C EN 14112 6 hours minimum

Phosphorus Content EN 14107 10.0 mg/kg maximum

Polyunsaturated (>4 double

bonds) methyl esters

1.00 %(m/m) maximum

Sodium and Potassium EN 14108, EN 14109 5.00 mg/kg maximum

Sulfated Ash Content ISO 3987 0.02 %(m/m) maximum

Sulfur ASTM D 5453 or other 10 mg/kg maximum

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total sulfur method

Total Contamination EN 12662

(ASTM D 5452)

24.0 mg/kg maximum

Viscosity @ 40°C EN ISO 310 3.50 – 5.00 mm2

Water Content EN ISO 12937 500 mg/kg maximum

As mentioned above, biodiesel may be produced from a variety of feedstocks, such as animal fat,

vegetables oils and in the longer perspective algae.. The cost involved in procuring, processing and

producing biodiesel from oils and fats as feedstock is rather high. The current production of animal

fat and vegetables oils is not sufficient to completely replace fossil diesel fuel.

In order to lower the costs of production of biodiesel and to widen its feedstock base, waste

cooking oil can be used. Certain quantities of used cooking oil are available all over the world.

These are generated locally wherever food is cooked or fried in oil, for example, hotels, restaurants,

KFC, etc. Mozambique does not have statistical data about the amounts of feedstock available.

Nevertheless, an educated guess can be made for waste cooking oil discarded annually in

Mozambique. This amount is about 360 million liters. This was done based on the estimated total

amount of 108 billion liters of WCO generated worldwide annually, the number of world

population (around 7.5 billion) and the number of population living in Mozambique which is about

25 million people.

Better disposal of used cooking oil creates a significant challenge because of problems associated

with dumping and possible pollution of water and land resources. Some of the used cooking oil is

used for soap preparation and as an oil additive for fodder production. Nevertheless, major

quantities of used cooking oil are dumped illegally into landfills and rivers causing environmental

pollution. [6] Use of cooking oil for biodiesel production will contribute to a reduction of

greenhouse gases as well as eliminate the pollution of landfills and water.

2.2 ADVANTAGES AND DISADVANTAGES OF USING BIODIESEL

The advantages of using biodiesel fall into three broad categories, environmental impact, energy

security and economic impact. Concerning environmental impact, biodiesel from vegetable oil

causes a 57% reduction in greenhouse gases compared to fossil diesel. Indeed, biodiesel from

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cooking oil has a 86% reduction in greenhouse gases compared to fossil diesel. [9] Some of the

harmful exhaust emissions are positively affected in that biodiesel reduces particulate matter by

47% compared to fossil diesel. [6] Ultimately, biodiesel is renewable, it is plant based, so what is

used can be regrown. [6]

Concerning energy security, it is important to consider that fossil oil is a limited resource. On the

other hand, biomass is a renewable resource and locally available in many countries. National

dependence on fossil oil is reduced by production of energy from locally available sources such as

biomass.

Concerning economic impact, the bioenergy sector employed 2.8 million people globally in 2014

[10] There is direct support for local agriculture: it is another way to support your farmer. [6]

It has also been found that engine life is longer: biodiesel is a natural lubricant. [6]

Finally, biodiesel has a pleasant exhaust smell: When burned, the fuel emits a fried food or barbecue

aroma. [6]

The table below, shows the world biodiesel production and capacity

Table 2.3 Worldwide Biodiesel Production and Capacity [11]

One of the attractive characteristics of biodiesel is that its use does not require significant

modifications to the existing diesel engine. However, there are problems with vehicle warranty and

biodiesel use and it has nearly 10% lower energy content and different physical properties

compared to conventional diesel oil, which will cause certain changes in the engine performance

and engine emission, including lower power output and higher content of nitrous oxides.

Nevertheless, biodiesel has a higher cetane number than diesel oil, no aromatics, and contains

oxygen. [6]

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Biodiesel reduces tailpipe Particulate Matter (PM), hydrocarbon (HC), and carbon monoxide (CO)

emissions from most modern four-stroke Compression Ignition (CI) or diesel engines. These

benefits occur because biodiesel contains 11% oxygen by weight. The fuel oxygen allows the fuel

to burn more completely, so fewer unburned fuel emissions result. This same phenomenon reduces

air toxics, which are associated with the unburned or partially burned HC and PM emissions. [12]

FAME is biodegradable—up to 4 times more degradable than petroleum diesel—non-toxic, and

has a mild, rather pleasant odour. [1]

Biodiesel contains no hazardous materials and is generally regarded as safe. A number of studies

have found that biodiesel biodegrades much more rapidly than conventional diesel. Users in

environmentally sensitive areas such as wetlands, marine environments, and national parks have

taken advantage of this property by replacing toxic petroleum diesel with biodiesel. [12]

Currently, the cost of biodiesel is high compared to conventional diesel oil because most of the

biodiesel is produced from pure vegetable oil. However, the cost of biodiesel can be reduced by

using low cost feedstock such as animal fat and used cooking oil. [6] As was mentioned above,

Mozambique does not have statistical data about the amounts of feedstock available.

2.3 THE TRANSESTERIFICATION PROCESS

The oils, found in used cooking oils, are compounds called triglycerides, which are large molecules

made up of various organic acids combined with glycerol, an alcohol. The main components of

vegetable oil usually called esters, are organic acids combined with other, lighter alcohols. The

conversion process, called transesterification, involves adding methanol or ethanol to the vegetable

oil. This converts the triglycerides into esters of methanol or ethanol, together with free glycerol.

[13]

Therefore, transesterification is the process of separating the fatty acids from their glycerol

backbone to form fatty acid esters (FAE) and free glycerol. Fatty acid esters commonly known as

biodiesel can be produced in batches or continuously by transesterifying triglycerides such as animal

fat or vegetable oil with lower molecular weight alcohols in the presence of a base or acid catalyst.

This reaction occurs stepwise, with monoglycerides and diglycerides as intermediate products. A

simple molecular representation of the reaction is shown below in fig 2.1. [14]

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Figure 2.1- Transesterification reaction

In that reaction, the vegetable oil or animal fat is reacted in the presence of a catalyst with an

alcohol (usually methanol) to give the corresponding alkyl esters (so, for methanol, the methyl

esters) of the fatty acid mixture that is found in the parent vegetable oil or animal fat. [15]

The transesterification reaction occurs stepwise as shown below in Figure 2.2 [16] .

R1R2R3ТG+CH3OH↔R2R3DG+МER1FA

R2R3DG+CH3OH↔R3МG+МER2FA

R3МG+CH3OH↔МER3FA+Glycerol

Figure 2.2- Transesterification reaction stepwise

where R1, R2, R3 are the alkyl groups of three different fatty acids, e.g., palmitic, oleic or linoleic

acids.

TG = Triglyceride

DG = Diglyceride

MG = Monoglyceride

ME = Methyl Ester

FA = Fatty Acid

Transesterification consists of various processes such as alkaline catalyzed, acid-catalyzed

esterification, acid–alkaline catalyzed (two stage) and noncatalyzed super critical methanol (Saka),

enzyme catalyzed, and heterogeneous catalyst transesterification process.

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The methods applied for biodiesel production from used cooking oil are similar to those of

conventional transesterification processes.

2.4 TRANSESTERIFICATION METHODS THAT HAVE BEEN USED FOR

CONVERTING USED COOKING OIL INTO BIODIESEL

Alkaline catalyzed transesterification process

In the alkaline catalyzed transesterification process, base catalysts such as sodium methoxide,

sodium hydroxide, potassium hydroxide and potassium methoxide are used. The alkaline catalyzed

transesterification process is most effective in converting triglycerides into esters when the free

fatty acid (FFA), any saturated or unsaturated monocarboxylic acids that occur naturally in fats,

oils, or greases but are not attached to glycerol backbones; these can lead to high acid fuels and

require special processes technology to convert into biodiesel, [13] level is less than 1%. It is the

most widely used process because it requires only moderate temperatures and lower pressures in

comparison to other transesterification methods and also there is a high conversion efficiency

(98%). This process requires only a small time and there is a direct conversion to FAME without

any intermediate steps. However, it becomes less effective when the free fatty acid level exceeds

1% because the FFA reacts with the most common alkaline catalysts (NaOH, KOH, and

CH3ONa) and forms soap, which inhibit the separation of ester from glycerin and which in turn

reduces the conversion rate. A certain amount of the alkaline catalyst is consumed, producing soap

and hence, the catalyst efficiency decreases. Many researchers have used sodium hydroxide NaOH

as an alkaline catalyst for the transesterification of used cooking oil. [13]

Acid-catalyzed transesterification process

In the acid transesterification process, acidic catalysts, such as sulfuric acid, phosphoric acid,

hydrochloric acid and organic sulfonic acid, are used. In this process, a strong acid is used as a

catalyst for esterification of the FFAs and the transesterification of triglycerides. This process does

not yield soap due to the absence of alkali material. The esterification of the FFAs to alcohol esters

is relatively fast, however; the transesterification of the triglycerides is very slow, taking several days

to complete. Another major problem with the use of acid catalyst is the formation of water which

stays in the reaction mixture and finally stops the reaction well before reaching completion. [13]

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Enzyme catalyzed transesterification process

FAME can also be produced from a biocatalytic transesterification process in the presence of an

enzyme, such as lipase. This process has many advantages over the chemical-catalyzed

transesterification process, for example no generation of byproducts, easy product removal, use of

moderate process conditions (temperature, 35 – 45 °C), and recycling of the catalysts. Enzymatic

reactions can successfully be used for the transesterification of used cooking oil because enzymatic

reactions are insensitive to the presence of free fatty acids and the water content of the feedstock.

Recently, four different lipases such as Mucor meihi, Candida antartica, Geotrichum candidum,

and Pseudomonas cepacia have been used as catalysts for the transesterification of olive oil,

soybean oil and, tallow in the presence of alcohol. It was reported that, lipase from C. viscosum

was found to give maximum biodiesel yield during the transesterification of jatropha oil. Maximum

ester yield (75%) was reported for the transesterification of palm kernel with ethanol in presence

of PS30 lipase as a catalyst.

Non-catalyzed Biox transesterification process

Due to the low solubility of methanol in oil, the rate of conversion of oil into ester is very slow. In

order to overcome this problem, a new technology, the Biox process, was developed by Prof. David

Boocock of the University of Toronto. This process uses a co-solvent, tetrahydrofuran to stabilize

the methanol. It requires only 5–10 min to complete the reaction. This system requires a low

operating temperature of 30°C. Tetrahydrofuran is the most extensively used co-solvent because

its boiling point is close to that of methanol. Firstly the process converts the free fatty acids, up to

10% free fatty acids contents, followed by the triglycerides through the addition of a cosolvent in

two steps, single phase continuous process at atmospheric pressure and temperature within 90 min

of reaction time. The cosolvent is then recycled and reused continuously in the process. [13]

Non-catalyzed supercritical transesterification process

In order to overcome the limitations of base and acid catalyzed transesterification process, a new

method called non-catalyzed supercritical methanol transesterification (Saka) process has been

developed. This requires very short time (only 4 min) for the completion of the transesterification

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process under supercritical conditions, temperature 350–400 °C and pressure more than 80 bar. It

avoids the complications of purification in the last stages. However, it requires a high alcohol to

oil ratio (42:1) and higher capital and operating cost. It also consumes more power. Another

limitation of this process is that it neither explains nor verifies any compliance of the free glycerol

to less than 0.02% as established in the ASTM D6584 or other equivalent international standards.

Therefore, more research work is needed to improve this technology to make it more economical

and technologically viable. [13]

Heterogeneous catalyst transesterification process

Considerable research has been done to find suitable solid acid or solid base catalysts for

heterogeneous catalyzed process. The use of a heterogeneous catalyst does not yield soap. Some

solid metal oxides like tin, magnesium and zinc are being used as solid catalysts. However, they end

up as metal soap or metal glycerates. This problem can be eliminated by using a complete

heterogeneous catalyst. It consists of a mixed oxide of zinc and aluminum which promotes the

transesterification process without the loss of catalyst. Most solid catalysts are alkali or alkaline

oxides coated over large surface area. Solid basic catalysts are more active than solid acid catalysts.

CaO is widely used as a solid basic catalyst as it poses many advantages such as longer catalyst life,

higher activity and requires only moderate reaction conditions. Compared to homogenous

catalyzed transesterification process, the solid catalyzed transesterification process can tolerate

extreme reaction conditions. The temperature could go from 70°C to as high as 200°C to achieve

more than 95% yield using MgO, CaO, and TiO2 catalysts.

Selection of a transesterification process depends on the amount of free fatty acid and water

content of the feedstock. Alkaline catalyzed transesterification process is most effective in

converting triglycerides into esters when free fatty acid level is less than 1%. KOH is the most

commonly used alkaline catalyst for producing biodiesel from waste cooking oil. When the FFA

content of feedstock is 1 wt.%, then an acid catalyzed transesterification process is most effective.

However, this process requires high catalyst concentration and high molar ratio leading to

corrosion problems. Enzyme catalyzed transesterification process is a promising alternative

method to all chemical-catalyzed reactions for the production of biodiesel from UCO. However,

yields, reaction times, and costs are still critical compared to alkaline catalyzed transesterification

process. [13]

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Biodiesel production scheme diagram is shown in Figure 2.3 [14]

Figure 2.3: Biodiesel production scheme diagram

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3 BIODIESEL PRODUCTION

For verifying the biodiesel production process at a laboratory scale, the lab work followed two

work task sequences. The first sequence concentrates on using pure compounds in the conversion

of jatropha oil to methyl esters and the second sequence starts from unpurified vegetable oil and

is split in three stages.

3.1 OBTAINING METHYL ESTERS FROM JATROPHA OIL

To obtain methyl esters from jatropha oil, laboratory test 1 was performed by using the following

reagents:

Jatropha oil

Methanol

Figure 3.1: Jatropha oil

Figure 3.1 shows the jatropha oil; this oil was obtained by crushing jatropha seeds in a press

machine. The jatropha seed came from Bilibiza in Cabo Delgado province of Mozambique, as

shown in figure 3.2.

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Figure 3.2 : Jatropha seed with peel

Figure 3.3 : Jatropha seed peeled

Figure 3.3 above shows the jatropha seed after removing the peel.

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Figure 3.4 : Pressing machine

The peeled jatropha seed was pressed in a pressing machine, as shown in figure 3.4 above.

Figure 3.5 below, shows the reagent methanol used in the transesterification reaction.

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Figure 3.5 : Methanol

Potassium hydroxide (KOH) was used as catalyst in this laboratory test as shown in figure

3.6 below. [17]

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Figure 3.6: Potassium Hidroxide (KOH)

Laboratory test 1:

The work sequence to obtain methyl esters from jatropha oil was as follows:

Jatropha oil (300.1g) was placed in a 500 ml round bottomed flask equipped with a Teflon-coated

magnetic stirring bar and a condenser potassium hydroxide (KOH, 5 g) in methanol (50 ml) was

added in one portion to the flask and the resulting suspension was stirred at 60 °C for 2.5 hr. The

reaction mixture was then cooled down to room temperature and transferred to a 1000 ml

separating funnel. The bottom layer (80 ml) was separated. Ethyl acetate (300 ml) was added to the

upper layer and solution obtained was thoroughly washed with three 250 ml portions of water.

The organic layer was placed in a 1000 ml flask and dried over calcium chloride (50 g).

Thereafter the calcium chloride was removed by filtration and the remaining product was washed

with a 50 ml portion of ethyl acetate. The filtrate was placed in a 1000 ml round bottomed flask.

The ethyl acetate was then evaporated and a yellow oily product was distilled under reduced

pressure.). (boiling point185-205°C/ 15-20 mm).

28

Figure 3.7: Transesterification reaction

Figure 3.7 above, illustrates the transesterification reaction after mixing jatropha oil, methanol and

potassium hydroxide. The reaction mixture obtained was transferred to a separating funnel and the

bottom layer separated, as shown in figure 3.8 below.

29

Figure 3.8: Reaction mixture in a separating funnel.

After that, the bottom layer (glycerine) was measured, as shown in figure 3.9 below.

30

Figure 3.9: Glycerine

31

Figure 3.10: The upper layer of the reaction mixture

32

Ethyl acetate shown in figure 3.11 below was added to the upper layer, figure 3.10 above, and the

solution obtained was thoroughly washed with three portions of water.

Figure 3.11: Ethyl Acetate

33

Figure 3.12: Solution first wash (ethyl Acetate + upper layer)

In the first wash, figure 3.12 above, the water is turbid and it becomes clearer after the second and

the third wash, as shown in figures 3.13 and 3.14 respectively.

34

Figure 3.13: Solution second wash (ethyl Acetate + upper layer)

35

Figure 3.14: Solution third wash (ethyl Acetate + upper layer)

36

Figure 3.15: Calcium chloride filtration

Figure 3.15 above, shows the organic layer placed in a 1000 ml flask and after drying over calcium

chloride.

The beginning of distillation process is shown in figure 3.16 below, where the container prepared

to collect the ethyl acetate is empty. After finishing the process, the ethyl acetate is removed from

the organic layer, figure 3.17 below.

The process ends with a yellow oily product, the methyl esters, shown in figure 3.18 further below.

37

Figure 3.16: Beginning of distillation process (organic layer purified)

Figure 3.17: End of distillation process (yellow oily product separated from ethyl acetate)

38

Figure 3.18: Methyl esters

After finishing the laboratory test 1, the following results were found:

─ Glycerine (Bottom layer) = 80 ml

─ Methyl Esters = 240 g

The acid number (AN) and pН of the final product were measured as:

The AN was calculated using the Physic-Chemical Methods of Food Analysis of Adolfo Lutz

Institute. [18]

The pH was measured using a pH Meter. [19]

─ pH = 6.87

─ AN = 0.27

Figures 3.19 and 3.20 below illustrate the two procedures:

39

Figure 3.19: Acid number determination

40

Figure 3.20: pH measurement

3.2 OBTAINING FATTY ACID METHYL ESTERS FROM VEGETABLE OILS

The work sequence to obtain fatty acid methyl esters from vegetable oils started from unpurified

vegetable oil and was split in three stages described in laboratory tests 2, 3 and 4.

Laboratory test 2:

Potassium hydroxide (4.5 g) was dissolved in 47.5 g of methanol; 55 ml of the solution obtained

was added at room temperature while mixing with 300 g of unpurified vegetable oil. The mixture

obtained was heated up to 60 °C and stirred for 30 minutes at this temperature. After one hour the

heavy glycerine fraction (46 ml, density about 1.25 g/cm3 at 20 °C) was isolated from the mixture.

41

The reaction mixture obtained after separation of the glycerine phase was mixed with the remaining

(about 7 ml) potassium hydroxide methanol solution. The mixture was stired for 30 minutes at

40°C; then 20 ml of unpurified glycerine was added (the heavy glycerine phase, density about 1.2

g/сm3 at 20 °C) and stired for another 30 minutes. (2 hours).

Then the mixing was stopped and the mixture standed; this resulted in the separation of glycerine

phase (30 ml, density about 1.15 g/сm3 at 20°C).

Thereafter the fatty acid methyl esters obtained was purified from the admixtures by heating in the

presence of a sorbent (silica gel). To do that, the ester fraction was mixed with 6 g of the sorbent

(silica gel) and heated up while mixing to about 70 °С within 30 minutes. A small amount (about 3

ml) of volatile compounds was distilled off during the heating; The reaction mixture was cooled

down with the sorbent (silica gel) to 20 °C; thereafter the sorbent (silica gel) was filtered off from

the fatty acid methyl esters.

270 g of the final, bright yellow fatty acid methyl ester was obtained after filtering.

The acid number and рН (water extract) of the final product was measured.

Figure 3.21: Transesterification reaction

Figure 3.21 above shows the transesterification reaction after mixing the unpurified vegetable oil,

methanol and potassium hydroxide.

42

Figure 3.22: Transesterification reaction

Figure 3.22 above shows the transesterification reaction between the reaction mixture obtained

after separation of the glycerine phase and potassium hydroxide methanol solution.

43

Figure 3.23: Separating funnel (reaction mixture + glycerine fraction)

Figure 3.23 above, shows the heavy glycerine fraction separated from the mixture, after

one hour.

44

Figure 3.24: Reaction mixture after separation

Figure 3.24 shows the fatty acid methyl esters obtained after separation from the glycerine

shown below in figure 3.25.

45

Figure 3.25: Glycerine

46

Figure 3.26: Separating funnel (reaction mixture + glycerine fraction)

Figure 3.26 above, shows the second separation of glycerine phase after mixing the mixture

obtained (Figure 3.24) with the remaining potassium hydroxide methanol solution and the

unpurified glycerine.

47

Figure 3.27: Purification process using a sorbent

In order to purify the fatty acid methyl esters obtained, a sorbent (silica gel) was used. The

process is shown in figure 3.27 above. Finally, a bright yellow fatty acid methyl ester was

obtained after filtering the sorbent, as shown in figure 3.28.

48

Figure 3.28: Fatty Acid Methyl Esters

After finishing the laboratory test 2, the following results were found:

─ Glycerine fraction 1 = 46 ml

─ Glycerine fraction 2 = 22 ml

─ Methyl Esters = 250 g

The acid number (AN) and pН of the final product were measured

─ pH = 5.14

─ AN = 0.25

49

Laboratory test 3:

Potassium hydroxide (5.2 g) was dissolved in 50 g of methanol; 55 ml of the obtained solution was

added at room temperature while mixing with 300 g of used frying oil. The mixture obtained was

heated up to 60 °C and stired during 30 minutes at this temperature. After one hour the heavy

glycerine fraction (49 ml, density about 1.25 g/сm3 at 20 °C) was isolated from the mixture.

The reaction mixture obtained after separation of the glycerine phase was mixed with the remaining

(about 10 ml) potassium hydroxide methanol solution. The mixture was stired up for 30 minutes

at 40 °C; then 20 ml of unpurified glycerine (the heavy glycerine phase, density about 1.2 g/сm3 at

20 °C) was added and stired for another 30 minutes. (2 hours).

Then the mixing was stopped and the mixture standed; this resulted in separation of glycerine

phase (31 ml, density about 1.1 g/сm3 at 20 °C).

Thereafter the fatty acid methyl esters obtained was purified from admixtures by heating up in

the presence of a sorbent (silica gel). To do that, the ester fraction was mixed with 6 g of the

sorbent (silica gel) and heated up while mixing to about 70 °С within 30 minutes. A small amount

(about 3 ml) of volatile compounds was distilled off during heating;

The reaction mixture with the sorbent (silica gel) was cooled down to 20 °C; thereafter the sorbent

(silica gel) was filtered off from the fatty acid methyl esters; 260 g of the ready-made bright yellow

fatty acid methyl ester was obtained after filtering.

The acid number and рН (water extract) of the final product was measured.

Figure 3.29 below, shows the transesterification reaction after mixing used frying oil, methanol and

potassium hydroxide.

50

Figure 3.29: Transesterification reaction

The heavy glycerine fraction which was isolated from the mixture, in a separating funnel,

is shown in figure 3.30 below.

51

Figure 3.30: Separating funnel (mixture + glycerine)

The glycerine fraction in a beaker, is presented in figure 3.31 below.

52

Figure 3.31: Glycerine

53

Figure 3.32: Reaction mixture and the remaining KOH & methanol

Figure 3.32 above, presents the mixture been stired up for 30 minutes after mixing with the

unpurified glycerine.

54

Figure 3.33: Separation of glycerine phase

As shown in figure 3.33 above, the mixture stood and this resulted in separation of glycerine

phase.

55

Figure 3.34: Glycerine

Figure 3.34 above, shows the glycerine obtained after the second reaction.

56

Figure 3.35: Methyl esters

Figure 3.35 above, shows the methyl esters before the purification process with silica gel,

presented in figure 3.36 below.

57

Figure 3.36: Silica gel

Figure 3.37 below, presents the methyl ester purification process with sorbent (silica gel).

58

Figure 3.37: Methyl esters purification process

Finally, a bright yellow fatty acid methyl ester liquid was obtained after filtering, as shown in

figure 3.38 below.

59

Figure 3.38: Methyl esters obtained after filtration

After finishing the laboratory test 3, the following results were found:

─ Glycerine fraction 1 = 47 ml

─ Glycerine fraction 2 = 30 ml

─ Methyl Esters = 260 g

The acid number (AN) and pH of the final product were measured

─ AN = 0.28

─ pH = 12.09

60

Laboratory test 4:

The reaction as above, in laboratory test 3, was performed, however the purification was made

differently. 6 g of the local grade whitening clay were used instead of the sorbent (silica gel). The

yield of methyl esters was measured and the grade of the obtained fatty acid methyl esters was

verified.

Figure 3.39: Transesterification reaction

Figure 3.39 above, shows the transesterification reaction where potassium hydroxide,

methanol and used frying oil reacts to obtain methyl esters and glycerol.

61

Figure 3.40: Separation of glycerine phase

The separation of the glycerine phase occurs in a separating funnel, as shown above in

figure 3.40

The methyl esters after separation are presented in figure 3.41 below.

62

Figure 3.41: Mixture obtained after separation

The reaction mixture obtained after separation of the glycerine phase is illustrated in figure 3.41

above.

63

Figure 3.42: Reaction mixture with the remaining solution

Figure 3.42 above, shows the mixture being stirred for 30 minutes after the adition of

unpurified glycerine.

The whitening clay shown in figure 3.43 below was used to purify the fatty acid methyl

esters by heating up to about 70 °C as illustrated in figure 3.44 below.

64

Figure 3.43: Whitening clay

65

Figure 3.44: Methyl esters purification process

Finally, figure 3.45 below shows the ready-made bright yellow fatty acid methyl ester

obtained after the cooling down and filtering the reaction mixture.

66

Figure 3.45: Methyl esters obtained after filtration

After finishing the laboratory test 4, the following results were found:

─ Glycerine fraction 1 = 46 ml

─ Glycerine fraction 2 = 26 ml

─ Methyl Esters = 240 g

The acid number (AN) and PН of the final product were measured

─ AN = 0.50

─ pH = 13.00

67

Table 3.1 Laboratory test data summary

Lab1 Lab2 Lab3 Lab4

Oil Jatropha

300 g

Unpurified veg.

oil 300 g

Used frying oil

300 g

Used frying oil

300 g

KOH 5 g 4.5 g 5.2 g 5.2 g

Methanol 50 ml 47.5 g 50 g 50 g

Ethyl Acetate

300 ml

Silica Gel

6 g

Silica Gel

6 g

Whitening clay

6 g

Water

250 ml x 3

Calcium Chloride

50 g

Ethyl Acetate

50 ml

Table 3.2 Laboratory test results

Lab1 Lab2 Lab3 Lab4

Methyl Esters 240 g 250 g 260 g 240 g

Glycerine 1 80 ml 46 ml 47 ml 46 ml

Glycerine 2 22 ml 30 ml 26 ml

Volatile

Compounds

3 ml 2.5 ml 2.0 ml

68

Table 3.3 pH of the Methyl Esters

Lab1 Lab2 Lab3 Lab4

pH Experiment 6.87 5.14 12.09 13.00

pH Literature 7.00 7.00 7.00 7.00

Table 3.4 AN of the Methyl Esters

Lab1 Lab2 Lab3 Lab4

AN Experiment 0.27 0.25 0.28 0.50

AN Literature 0.50 0.50 0.50 0.50

69

4 RESULTS AND DISCUSSION

Figure 4.1 below shows the values of the experimental FAME pH found in comparinson to the

values of the literature pH.

Figure 4.1: Expected pH value vs. laboratory results graph

Figure 4.2 below shows the values of the experimental FAME AN found in comparison to the

values of the literature AN.

Figure 4.2: Expected AN value vs. FAME laboratory AN graph

70

5 CONCLUSIONS

This thesis project aimed at verifying the production process for biodiesel from jatropha

seed oil and from waste cooking oil at small scales in the perspective of Mozambique.

Local biodiesel production could not only provide a solution to the problem of finding

alternative fuels to firewood, charcoal and fossil fuels, but also could make use of

underutilized locally available resources such as jatropha seeds and waste cooking oil,

thus avoiding the disposing of these products to the environment as waste materials .

In addition, there are also advantages in economic terms, since cooking oil processing,

although considered waste acquires economic value, creates new jobs, and reduces the

dependence of Mozambique on the import of foreign fuels ; as well as jatropha plantations

could provide livelihood and local fuel production for rural communities.

Having completed the thesis work the following conclusions could be reached based on the analysis

of the results, for the practical application case in Mozambique:

Biodiesel can be produced from jatropha oil.

Biodiesel can be produced from waste cooking oil.

Biodiesel can be produced at both small- and large scales in Mozambique.

Although it was possible to produce biodiesel within the local context, there are some aspects to

consider in terms of AN and pH determination. An acid number value of 0.33 on average was

obtained. This value is acceptable because the maximum AN value is 0.5 mgKOH/g. Regarding

pH results, a value of 9.28 on average was encountered, while the threshold is around 7 pH, that is

neutral, in order to avoid corrosion of vital fuel system components: fuel pumps, injector pumps,

fuel lines, etc. [20]

The results above were obtained despite various difficulties encountered during the laboratory

tests. Firstly, some reagents were obsolete, consequently it was necessary to repeat the laboratory

tests several times, secondly, some equipment was not working properly because certain accessories

were missing. In order to meet this difficulty some parts were adapted to replace the missing ones.

71

6 RECOMMENDATIONS

In 2009 the Government of Mozambique approved the Policy for the Development of New and

Renewable Energies, establishing, as one of the implementation strategy priorities, the evaluation

of new and renewable energy resources. [21]

The public reaction to jatropha planting in the country is positive, because the government set a

policy on jatropha planting in order to avoid conflits with other crops planting. This governmental

policy consists of:

Consulting and educating the local population living in the areas were the jatropha planting

would take place.

Authorizing a temporary concession of the land use, named DUAT (for 2 years).

Authorizing a definitive concession of the land use for 50 years, if the project succeeds.

There are only two projects on biodiesel production currently running in Mozambique, one in

Cabo Delgado province, Bilibiza district financed by JICA; and another in Sofala province, Buzi

district financed by Niqel company.

Recovery of waste cooking oil (WCO) plays an essential role in both the environmental and

economic sustainability of biodiesel. A total of 108 billion liters of WCO is estimated to be

generated annually worldwide, but still, out of this quantity only 6 billion liters are collected and

used in biodiesel production. In addition to the economic savings, collecting WCO also benefits

the environment by decreasing the contamination of rivers, lakes or oceans. WCO along with waste

animal fat is an ecotoxic agent, and accounts for 25% of waste water pollution. One liter of WCO

poured down the drain can contaminate one million liters of water and cause serious damage to

the ecological life. [22]

An educated guess was made for waste cooking oil discarded annually in Mozambique. This

amount tends to be about 360 million liters. This was done based on the estimated total amount

of 108 billion liters of WCO generated worldwide annually, the number of world population

(around 7.5 billion) and the number of population living in Mozambique which is about 25 million

people as of 2016.

72

The amount mentioned above is significant enough to recommend an investigiation into making

an investment to produce biodiesel from WCO at a large scale, nationwide.

According to the context described above (the policy for the Development of New and Renewable

Energies, the policy for jatropha planting and the educated guess for the waste cooking oil

generated annually) Mozambique has a relatively large and stable availability of resources to

produce biodiesel on a nationwide scale at acceptable renewability index level with minimum

impact on the environment. Therefore it is recommended that biodiesel production from jatropha

and waste cooking oil, using the local feedstock, is initiated and deployed more broadly in the

country. This will improve the environment by the reduction of the pollution levels in the

atmosphere and contribute to energy independence in Mozambique. However, further studies are

needed to carefully evaluate the economy parameters and the actual sustainability for the biodiesel

production and utilization in each locality.

73

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75

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