ABSTRACT
In this work, Transesterification of waste vegetable oil has been carried out using Anthill as the catalyst. Anthill was utilized as raw material for catalyst production for biodiesel preparation. During calcination process, the calcium carbonate content in the anthill was converted to CaO with Al₂O₃ as the promoter and SiO₂ as the support. This calcium oxide was used as catalyst for transesterification reaction between waste cooking oil and methanol to produce biodiesel. The biodiesel preparation was conducted under the following conditions: the mole ratio between methanol and palm oil was 6:1 and with catalyst of 7wt %. The catalyst activation temperature, reaction temperature and reaction time was varied at 600-1000°C, 60-70°C and 1-3h respectively. The maximum yield of biodiesel was 63.14%, obtained at 3h of reaction time and 70°C. Anthill has potential application as a source of catalyst for synthesis of biodiesel of high purity. The catalyst was obtained by calcinations of anthill at 600-1000°C for 3h. The maximum yield of biodiesel produced by transesterification of waste cooking oil with methanol was 63.14%. The operating condition to achieve the maximum biodiesel yield is: the ratio of oil to methanol 1:6, the amount of catalyst 7%, reaction time 3h, reaction temperature 70°C.
TABLE OF CONTENTS
CERTIFICATION………………………………………………………………………………………………………….. ii
DEDICATION………………………………………………………………………………………………………………. iii
ACKNOWLEDGEMENT………………………………………………………………………………………………. iv
ABSTRACT…………………………………………………………………………………………………………………… v
LIST OF FIGURES……………………………………………………………………………………………………… viii
LIST OF TABLES………………………………………………………………………………………………………….. x
NOMENCLATURE………………………………………………………………………………………………………. xi
CHAPTER ONE…………………………………………………………………………………………………………….. 1
CHAPTER TWO…………………………………………………………………………………………………………….. 5
2.4. Vegetable Oil for Transesterification…………………………………………………………………… 13
CHAPTER 3…………………………………………………………………………………………………………………. 23
CHAPTER 4…………………………………………………………………………………………………………………. 30
CHAPTER 5…………………………………………………………………………………………………………………. 38
REFERENCE……………………………………………………………………………………………………………….. 39
APPENDIX………………………………………………………………………………………………………………….. 42
LIST OF FIGURES
Figure 1.1. Transesterification reaction……………………………………………………………………………….. 2
Figure 2.1. Overall mechanism of Transesterification…………………………………………………………… 6
Figure 2.2. Structure of Vegetable Oil………………………………………………………………………………. 14
Figure 2.3. Block diagram of an FTIR spectrometer……………………………………………………………. 19
Figure 3.1. Process for catalyst preparation………………………………………………………………………… 26
Figure 3.2. The sieved oil………………………………………………………………………………………………… 26
Figure 3.3. pH meter………………………………………………………………………………………………………. 27
Figure 3.4. Atmospheric mud balance……………………………………………………………………………….. 27
Figure 3.5. Marsh funnel…………………………………………………………………………………………………. 28
Figure 3.6. Process of biodiesel production………………………………………………………………………… 29
Figure 3.7. Synthesized biodiesel before separation……………………………………………………………. 30
Figure 4.1. SEM of raw anthill………………………………………………………………………………………… 32
Figure 4.2. SEM AT 800 °C……………………………………………………………………………………………. 33
Figure 4.3. SEM AT 1000 °C………………………………………………………………………………………….. 33
Figure 4.4. Biodiesel yield against catalyst activation temperature………………………………………… 34
Figure 4.5. Biodiesel yield with time…………………………………………………………………………………. 35
Figure 4.6. Biodiesel yield with temperature………………………………………………………………………. 35
Figure 4.7. Waste cooking oil FTIR spectrum…………………………………………………………………….. 36
Figure 4.8. Waste cooking oil derived biodiesel at 800°C……………………………………………………. 36
Figure 4.9. GCMS data………………………………………………………………………………………………….. 37
Figure 4.10. GCMS with data band matching number……………………………………………………….. 37
LIST OF TABLES
Table 2.1. Properties of biodiesel compared to diesel………………………………………………………….. 10
Table 2.2. Comparison of homogenous and heterogeneously catalyzed transesterification………. 12
Table 2.3. Compositional analysis of ant-hill clay………………………………………………………………… 13
Table 4.1. Oil analysis result…………………………………………………………………………………………….. 31
Table 4.2. Composition of anthill……………………………………………………………………………………… 31
Table 4.3. Fatty acid contents of each oil represent the composition of methyl esters in biodiesel 38
NOMENCLATURE
| FAME | Fatty Acid Methyl Ester |
| SEM | Scanning Electron Microscope |
| FTIR | Fourier Transform Infrared |
| FFA | Free Fatty Acid |
| XRF | X-Ray Fluorescence |
| GC-MS | Gas Chromatograhy-Mass Spectrometry |
| A/D | Analog to Digital |
| XRD | X-Ray Diffraction |
CHAPTER ONE
INTRODUCTION
Research Background
Currently there is an urgent need to develop alternative energy resources, such as biodiesel fuel due to the gradual reduction of world petroleum reserves, its economic and social concerns and the environmental pollution of increasing exhaust emissions of harmful gases like SOx, NOx, and Cox, coupled with the steady increase in energy consumption have spurred research interest in alternative and renewable energy sources. A successful substitute for diesel fuel, used mainly in the transportation sector, was found to be the mixture of the ester derivatives from the vegetable oils and animal fats. This new feedstock is environmental friendly, renewable, and totally in- dependent from petroleum
Biodiesel is a renewable, biodegradable fuel that can be manufactured domestically from vegetable oils, animal fats, or recycled restaurant grease. It is a cleaner-burning replacement for petroleum diesel fuel. Biodiesel is defined as the mono-alkyl esters of vegetable oils or animal fats, obtained by transesterification of oils or fats with an alcohol, usually methanol or ethanol. The major component of vegetable oil is triglycerides. When the triglycerides react with alcohol in the presence of base catalyst, this is called “transesterification.” In this reaction, triglycerides are converted to diglyceride, monoglyceride, and finally converted to glycerol. The reaction occurs in three steps. In the first step, a triglyceride reacts with an alcohol molecule producing a diglyceride
–ester and then the diglyceride reacts with another alcohol molecule producing a mono-glyceride and another mono-ester, and finally, the mono- glyceride reacts with another alcohol molecule giving glycerin and another mono-ester. (Vonortas and Pappayanakos, 2014)
Figure 1.1. Transesterification reaction
The parameters affecting the transesterification reaction are temperature, molar ratio of alcohol to oil, type and quantity of catalyst, the type of the process, and the composition of the reactants mixture.
Catalyst is any substance that increases the rate of a chemical reaction. Catalyst are not consumed during a reaction therefore it is possible to recycle them. The process for producing biodiesel use different catalyst
- Homogenous (NaOH, KOH, H2SO4)
- Biocatalyst (lipases)
- Heterogeneous (metal hydroxides, metal complexes and metal oxides like calcium oxide, magnesium oxide, zeolites etc.)
Homogenous catalyst is a catalyst that is in the same phase with the reactant while heterogeneous catalyst means that the catalyst are in different phase with the reactant. Biocatalyst are known as the enzyme catalyst.
It has been estimated that the cost of biodiesel produced from virgin vegetable oil through transesterification is higher than that of fossil fuel, because of high raw material cost. This has
hindered wider utilization and commercialization of future biodiesel plant. To minimize the biofuel cost, in recent days, cheaper feedstock such as low-grade oil, typically waste cooking oil is being used as feedstock. The high viscosity and poor volatility are the major limitation of using vegetable oil in diesel engines. (Paugazhabadivu et al., 2005). Large amount of waste cooking oil is generated from eatery establishment, restaurant and food industry etc. every year, discarding of this oil can be of a challenge since it has the probability of contaminating the environment. (Hubera et al., 2007). Accordingly, this research work will focus on biodiesel production from waste cooking oil using thermally activated anthill.
Problem Statement
Homogenous catalyst result in complex separation and purification process steps due to its high saponification. Catalyst gotten from anthill has never been recorded to be used in biodiesel production based on the previous research. The competition of using edible vegetable oil in the production of biodiesel in place of food stock has made it a wrong choice for biodiesel production. Waste vegetable oil poses an environmental concern in the disposal. Depletion of petroleum reserves makes dependence on it as the only source of energy a problem.
Aim
This research project is aimed at the investigation of anthill as a suitable catalyst for the production of biodiesel by transesterification.
Objectives
- Preparing the anthill catalyst at varied activation temperature.
- Varying the time during biodiesel production
- Varying the temperature and time of the reaction
Scope of Study
The scope of my study covers the production of biodiesel using anthill as catalyst. Various samples of the anthill catalyst at various activation temperature will be tested during the biodiesel production while varying the methanol to oil ratio, temperature and time of reaction to find out the optimum conditions for the best conversion of the biodiesel.
Motivation/Significance of Study
In most of hotels, restaurants, and in other food industries, the waste cooking oil is either simply discharged into the river or dumped into the land, In spite of this, the waste cooking oil can be used effectively for the biodiesel synthesis. Biodiesel production from waste cooking oil is found to be economically feasible method. This research is proposed to improve the capability of waste cooking oil as a biodiesel feedstock in the present worldwide due to the increasing demand of biodiesel, the environmental concern and limited resources of petroleum oil. Many researches before use waste cooking oil to produce but none has used anthill as a catalyst for the biodiesel production. Hence, this research is to investigate if using anthill as a catalyst will give a good yield and the parameter suitable for the yield.
Biodiesel have so many advantages such as, is a renewable energy sources, safe for use in all conventional diesel engines, offers the same performance and engine durability as petroleum diesel fuel, non-flammable and nontoxic, reduces tailpipe emissions, visible smoke and noxious fumes and odors. So, waste cooking oil is used as a raw material to substitutes the petroleum because it provides a safer means of disposing of the oil.
Justification
- Availability of anthill across the nation and abundant quantity of waste cooking oil
CHAPTER TWO
THEORECTICAL BACKGROUND
Biodiesel
Biodiesel is said to be any fuel comprised of mono-alkyl esters of long chain fatty acids. Biodiesel is produced from any fat or oil through a process called transesterification. In the production of biodiesel, the triglycerides present in various sources viz. edible oil, nonedible oil, animal fats, waste oil and oil from algae are transesterified with methanol in presence of a catalyst (acid, base or biocatalyst) to afford fatty acid methyl esters (FAME) and glycerol as a byproduct. It is a clean fuel as it has no sulphur, no aromatics and has 10% oxygen, which helps its complete in internal combustion (IC) engines. Its higher cetane number leads to improved ignition quality, even in petroleum diesel blends. (Vicente et al., 2007). A successful transesterification reaction is signified by the separation of the ester and glycerol layers after the reaction time. The heavier, co-product, glycerol settles out and may be sold as it is or it may be purified for use in other industries, e.g. the pharmaceutical, cosmetics etc. Biodiesel benefits us both economically and environmentally in the following ways:
- It is renewable.
- It is energy efficient.
- It displaces petroleum-derived diesel fuel.
- It can be used as a 20% blend in most diesel equipment with no or only minor modifications.
- It can reduce global warming gas emissions.
- It can reduce tailpipe emissions, including air toxics.
- It is nontoxic, biodegradable, and suitable for sensitive environments.
- Longer engine life: Biodiesel is a natural lubricant.
- Pleasant exhaust smell: When burned, the fuel emits a fried food or barbecue aroma.
CONCERNS
- Requires special handling in cold weather.
- Slightly less energy content than diesel fuel.
- Tends to deteriorate non-synthetic or natural rubber fuel system parts (hoses, seals).
- Depending upon the state of engine tune, there can be slightly higher levels oxides of nitrogen in exhaust emissions.
Figure 2.1. Overall mechanism of transesterification
Production routes
There are three basic routes to biodiesel production from oils and fats:
- Base catalyzed transesterification of the oil.
- Direct acid catalyzed esterification of the oil.
- Conversion of the oil to its fatty acids and then to biodiesel.
Base catalyzed transesterification of the oil
The transesterification reaction is base catalyzed. Any strong base capable of deprotonating the alcohol will do (e.g. NaOH, KOH, Sodium methoxide, etc.). Commonly the base (KOH, NaOH) is dissolved in the alcohol to make a convenient method of dispersing the otherwise solid catalyst into the oil. The ROH needs to be very dry. Any water in the process promotes the saponification reaction, thereby producing salts of fatty acids (soaps) and consuming the base, and thus inhibits the transesterification reaction. Once the alcohol mixture is made, it is added to the triglyceride. The reaction that follows replaces the alkyl group on the triglyceride in a series of steps as seen in EQUATION 2.1. The carbon on the ester of the triglyceride has a slight positive charge, and the carbonyl oxygen have a slight negative charge. This polarization of the C=O bond is what attracts the RO- to the reaction site.
(2.1)
Factors Affecting Transesterification
There are several parameters that effect the oil transesterification process. These include the free fatty acid value (FFA), catalyst type and content, molar ratio of alcohol to oil, temperature, and mixing intensity.
Free fatty acid value: The free fatty acid content of an oil determines the conversion efficiency of the process. For the base catalyzed method, the FFA must be less than 3%. Feedstock oils with a high acid content result in a lower conversion efficiency and require an excessive amount of base to be added for the reaction to proceed. This excessive amount of base can lead to additional formations of soap and increase the viscosity of the fuel, reducing its applicability.
Catalyst type and content: Oils with high acid content require an acid catalyst to be used. These catalyst however, have been found to be far less efficient than alkali, of basic catalysts. In fact, reactions have been noted to proceed up to 4000 times faster when an alkaline is present instead of an acid. The content of the catalyst also directly relates to the amount of oil that is converted to esters. For a base catalyzed process, an optimal ratio of catalyst to oil has been determined to be in the range of 0.5 to 1.0 wt%, resulting in 94% to 99% conversion of vegetable oil to esters. Increased amounts of catalyst content has not been found to have a negative impact on conversion but does increase of the cost of the process due to the additional material required and steps involved in catalyst recovery.
Molar ration of alcohol to oil: The molar ratio of alcohol to oil also effects the reaction since the reaction is stoichiometric. By adding an excess of alcohol at a ratio of 6:1, drives the reaction towards the products and increases the yield of esters. Increasing the ratio has no negative effect on the actual transesterification process, but does complicate the separation of glycol from ester
i.e. it increases the solubility. This requires that the optimal ratio is determined as a function of ester yield and separation costs for industrial applications.
Temperature: The temperature at which the transesterification is carried out highly effects the rate of the reaction. Though the reaction will proceed to completion at room temperatures, it is typically conducted at 60 °C to 70 °C under atmospheric pressure for industrial processes that use methanol.
Mixing intensity: The rate of reaction is also dictated by the interactions between the oil and catalyst. For most applications a base catalyzed process is used which results in an immiscible solution. Mixing is used to force interactions between the oil and catalyst. Once the solution is mixed the reaction will proceed and the mixing process can be stopped but it is important to
examine the rate of mixing that is required to achieve this state the most efficiently. (Murugesana
et al., 2009).
Direct acid catalyzed esterification of the oil
Free fatty acids can be esterified and O-acyl lipids, such as triacylglycerol, can be transesterified by heating them with a large excess of anhydrous methanol and an acidic reagent as catalyst. If any water is present, it inhibits the reaction and may prevent it going to completion. The commonest and mildest reagent is 5 wt% anhydrous hydrogen chloride in methanol, and it is most often prepared by bubbling hydrogen chloride gas (which is commercially available in cylinders or can be prepared by dropping concentrated sulphuric acid slowly on to fused ammonium chloride or into concentrated hydrochloric acid) into dry methanol as seen in EQUATION 2.2. This method is best suited to bulk preparation of the reagent.
(2.2)
Almost all biodiesel is produced using base catalyzed transesterification as it is the most economical process requiring only low temperatures and pressures and producing a 98% conversion yield. For this reason only this process will be described in this report.
Table 2.1. Properties of biodiesel compared to diesel
| Fuel Property | Biodiesel | Diesel |
| Fuel Standard | ASTM D6751 | ASTM |
| Higher Heating Value (Btu/gal) | 127,042 | 137,640 |
| Lower Heating Value (Btu/gal) | 118,170 | 129,050 |
| Kinematic Viscosity @ 40ºC (104ºF) | 4.0–6.0 | 1.3–4.1 |
| Specific Gravity (kg/l) @ 15.5ºC (60ºF) | 0.88 | 0.85 |
| Density, lb/gal@ 15.5ºC (60ºF) | 7.3 | 7.1 |
| Carbon, (wt %) | 77 | 87 |
| Hydrogen, (wt %) | 12 | 13 |
| Oxygen (wt %) | 11 | 0 |
| Sulfur, (wt %) | 0.0–0.0024 | 0.0015 max |
| Boiling Point, ºC (ºF) | 315–350 (599–662) | 180–340 |
| Flash Point, ºC (ºF) | 100–170 (212–338) | 60–80 |
| Cloud Point, ºC (ºF) | -3 to 15 (26 to 59) | -35 to 5 (-31 |
| Pour Point, ºC (ºF) | -5 to 10 (23 to 50) | -35 to -15 (- |
| Cetane Number | 48–65 | 40–55 |
In the production of biodiesel, a catalyst is used to promote transesterification.
Catalyst
A catalyst is a chemical compound that enables a chemical reaction to proceed at a usually faster rate or under different conditions (as at a lower temperature) than otherwise possible. They increase the rate of a reaction by lowering the activation energy required to reach the transition state. Unlike reactants, a catalyst is not consumed as part of the reaction process.
The transesterification reaction for biodiesel production can be carried out using both homogeneous (acid or basic) and heterogeneous (acid, basic or enzymatic) catalysts.
Homogenous catalyst
Homogeneous catalysts function in the same phase (liquid, gaseous, etc.) as the reactants. Homogeneous catalysts are dissolved in a solvent with the substrates. Examples are transition
metal ions, transition metal complexes, inorganic acids and bases, enzymes (these are dealt with in a separate section below)
Advantages
- There is good contact with reactants so a much greater effective concentration of catalyst than with heterogeneous catalysts. This means that to achieve the same rate milder conditions can be used and so it is possible to achieve greater selectivity.
- At the research and development stage it is often quicker and simpler to work with homogeneous catalysts, and then find ways of making the system heterogeneous for industrial application.
Disadvantages
- The catalyst needs to be separated after reaction. This separation can involve distillation.
- In some cases this makes catalyst recovery difficult because the temperature needed for the distillation can destroy the catalyst
Heterogeneous catalyst
Heterogeneous catalyst occurs in a different phase than the reactants. Most heterogeneous catalysts are solids that act on substrates in a liquid or gaseous reaction mixture. The total surface area of solid has an important effect on the reaction rate. The smaller the catalyst particle size, the larger the surface area for a given mass of particles. Examples Transition metal oxides, zeolites, silica/alumina.
Advantages
- There is little difficulty in separating and recycling the catalyst.
Disadvantages
- There is a lower effective concentration of catalyst since the reaction occurs only on the exposed active surface.
- To maximize the surface area catalysts are spread thinly on a cheap and sturdy support. In the case of some metals a fine mesh is used, such as the Pt mesh used to catalyze the oxidation of ammonia.
Table 2.2. Comparison of homogenous and heterogeneously catalyzed transesterification
| Factors | Homogeneous Catalysis | Heterogeneous Catalysis |
| Reaction Rate | Fast and high conversion | Moderate conversion |
| After treatment | Catalyst cannot be recovered, must be neutralized leading to waste chemical production | Can be recovered |
| Processing methodology | Limited use of continuous methodology | Continuous fix bed operation is possible |
| Presence of water/free fatty acids | Sensitive | Not sensitive |
| Catalyst reuse | Not possible | Possible |
| Cost Comparatively | Costly | Potentially cheaper |
| Environment concern | Salt and aqueous wastes | No waste stream |
Common problem encountered while using heterogeneous catalyst for transesterification are higher catalyst cost and requirement for elaborate procedures for catalyst preparation. These are hoped to be overcome by using the anthill as a catalyst.
Anthill
An ant-hill is a pile of earth, sand, pine needles, or clay or a composite of these and other materials that build up at the entrances of the subterranean dwellings of ant colonies as they are excavated.
Table 2.3. Compositional analysis of ant-hill clay
| Constituent | SiO₂ | Al₂O₃ | Fe₂O₃ | TiO₂ | CaO | MgO | Na₂O | K₂O | L.O.I | Total |
| Percentage composition | 58.83 | 22.69 | 2.42 | 0.72 | 0.01 | 0.84 | 0.06 | 2.10 | 12.33 | 100% |
This shows that that the sample contained a high percentage of silica. The mound/hill can, therefore, be classified under siliceous fireclay. This result further showed that the clay belongs to the fireclay accepted standard and falls within the range of semi-plastic fireclays. The second highest occurring content is alumina Al₂O₃ which can serve as a promoter which helps to improve the effectiveness of a catalyst.
Vegetable Oil for Transesterification
- Vegetable oil
Vegetable oil mostly contains tri-glycerol up to 98% with the presence of some fatty acids, diglycerides and mono-glycerides. Fatty acid values vary between C6-C24 having mostly C16-C18 which are saturated or mono-saturated as well as sometimes poly-unsaturated nature.
The classification of Vegetable oil according to the composition can be put as
- Saturated (palmitic acid, mysteric acid, stearic acid and lauric acid)
- Mono-saturated (erucic acid, oleic acid and petroselinic acid)
- Poly-unsaturated (lenolenic acid, lenoliec acid, ricinoliec acid, eleostearic acid and verolic acid).
Fatty acids are very important because of the fact that the properties of triglycerides and biodiesel fuels depends upon the quantity of fatty acids in molecules that is the soap formation in presence of NaOH or KOH. (Van, 2004)
Vegetable oil chemical structure
Figure 2.2. Structure of vegetable oil
The high viscosity and poor volatility are the major limitations of vegetable oils for their utilization s fuel in diesel engines. Because high viscous vegetable oils deteriorate the atomization, evaporation and air-fuel mixture formation characteristics leading to improper combustion and higher smoke emission. Moreover this high viscosity generates operational problems like difficulty in engine starting, unreliable ignition and deterioration in thermal efficiency. Converting to biodiesel is one of the options to reduce the viscosity of vegetable oils (Paugazhabadivu et al., 2005).
The engine combustion benefits of the transesterification of the oil are:
- Lowered viscosity
- Complete removal of the glycerides
- Lowered boiling point
- Lowered flash point
- Lowered pour point
2.4.2. Environmental problems for disposing used cooking oil
Used cooking oil causes severe environmental problems, a liter of oil poured into a water course can pollute up to 1000 tanks of 500 liters. The oil which reaches the water sources increases its organic pollution load, to form layers on the water surface to prevent the oxygen exchange and alters the ecosystem. The dumping of the oil also causes problems in the pipes drain obstructing them and creating odors and increasing the cost of wastewater treatment. For this reason, has been necessary to create a way to recover this oil and reuse it. Also due to the wear and tear resulting in sewer pipes may cause overflows of the system, “generating diseases that can cause mild stomach cramps to diseases potentially fatal, such as cholera, infectious hepatitis and gastroenteritis, due to the sewage contains water which can transport bacteria, viruses, parasites, intestinal worms and molds. The dangerous odors generate impact negatively on health, “is formed hydrogen sulfide (H2S), which can cause irritation of the respiratory tract, skin infections, headaches and eye irritation” (Guerrero et al., 2011).
Characterization Methods for Catalyst and Biodiesel
- X-ray fluorescence (XRF)
An X-ray fluorescence (XRF) spectrometer is an x-ray instrument used for routine, relatively non- destructive chemical analyses of rocks, minerals, sediments and fluids. The analysis of major and trace elements in geological materials by x-ray fluorescence is made possible by the behavior of
atoms when they interact with radiation. When materials are excited with high-energy, short wavelength radiation (e.g., X-rays), they can become ionized. If the energy of the radiation is sufficient to dislodge a tightly-held inner electron, the atom becomes unstable and an outer electron replaces the missing inner electron. When this happens, energy is released due to the decreased binding energy of the inner electron orbital compared with an outer one. The emitted radiation is of lower energy than the primary incident X-rays and is termed fluorescent radiation. Because the energy of the emitted photon is characteristic of a transition between specific electron orbitals in a particular element, the resulting fluorescent X-rays can be used to detect the abundances of elements that are present in the sample. X-Ray fluorescence is used in a wide range of applications, including
