AU2006100428A4 - Production of biodiesel - Google Patents

Description

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION FOR AN INNOVATION PATENT Name of Applicant: Actual Inventor: Address for Service: Invention Title: The University of Tasmania, Churchill Avenue, Sandy Bay, Tasmania 7001, Australia Vishy KARRI DAVIES COLLISON CAVE, Patent Attorneys, of 1 Nicholson Street, Melbourne, Victoria 3000, Australia "Production of Biodiesel" The following statement is a full description of this invention, including the best method of performing it known to us: -1- Q:\OPER\JCC\ARCHIVE\2006\M4AY\12756500230506JCC FILING.DOC 23/5/06 -2- Production of Biodiesel The present invention relates to a method for the production of biodiesel, and to C biodiesel produced by the method Biodiesel is typically produced by reaction of a vegetable oil or animal fat with an 00 Ci alcohol, such as ethanol or methanol, in the presence of a catalyst to yield mono-alkyl O esters (biodiesel) and glycerin. Conventional methodology for the production of biodiesel Stends to focus on the use of oil/fat feedstocks that are relatively highly saturated and that 0therefore have a low iodine value Saturated feedstocks tend to be used because NI 10 problems can be encountered when high IV feedstocks are used in biodiesel production.

Biodiesel made from high IV oils/fats is not particularly storage stable and its use in internal combustion engines can lead to the formation of insoluble plastic-like deposits on internal surfaces of engines and engine components, such as injector pumps. These deposits form as a result of oxidation of high IV species in the biodiesel and this process is accelerated at the kind of elevated temperatures at which an engine is operated. Oxidation of high IV species in biodiesel can also result in formation of by-products (e.g.

hydroperoxides) that corrode elastomeric engine compounds, such as rubber seals. Against this background it would be desirable to produce biodiesel from high IV oils/fats that does not suffer these drawbacks.

Production of biodiesel from high IV oils would also be advantageous from a supply perspective since this would provide manufacturing flexibility. This may also have cost implications, especially where the high IV oil/fat to be used is readily available.

Accordingly, the present invention provides a method of producing biodiesel, which method comprises: forming a blend of triglyceride oils comprising a first triglyceride oil having an iodine value of from 30-110 and a second triglyceride oil having an iodine value of 130- 145, wherein the first and second triglyceride oils are selected such that the difference in their iodine values is from 40-80 and wherein the ratio by volume in the blend of the first triglyceride oil to the second triglyceride oil is from 70:30 to 90:10; reacting the blend of triglyceride oils with an alcohol in the presence of a catalyst to form mono-alkyl esters and glycerin; separating the mono-alkyl esters and glycerin; and -3removing residual alcohol from the mono-alkyl esters to produce biodiesel.

c Herein the iodine value (IV) of a triglyceride oil is a measure of the degree of unsaturation of the oil. It is generally expressed in terms of the number of grams of iodine i that will react with the double bonds in 100Og of the oil. A high IV oil contains a greater number of carbon-carbon double bonds than a low IV oil. For the purposes of the present 00 invention IV is taken to be determined in accordance with ASTM method D1959-97 (also known as the Wijs method).

An important aspect of the present invention resides in the blend of triglyceride oils that is used. This comprises first and second triglyceride oils having the characteristics 10 noted above. It is possible to use more than two triglyceride oils to form the blend and in this case the relationship set out above should still be observed. For example, if the blend is made up of three triglyceride oils, two of the oils must satisfy the IV requirement of the first (or second) triglyceride oil set out above and the third oil must satisfy the IV requirement of the second (or first) triglyceride oil set out above. In this case the difference between the IV for the, or each, triglyceride oil having an IV of 30-110 and the IV of the, or each, triglyceride oil having an IV of 130-145 is as called for above, i.e. the difference is from 40-80. Typically, the blend has an IV of 80-120.

Triglyceride oils useful in practice of the present invention are commercially available. Representative examples of triglyceride oils that may be useful in practice of the present invention are given in the following table Oils and their melting points and Iodine Values Approx.

Approx. Iodine Value Oil melting point (typical) (typical) deg C oconut oil 25 alm kernel oil 24 37 utton tallow 42 eef tallow alm oil 35 54 Olive oil -6 81 Castor oil -18 Peanut oil 3 93 Rapeseed oil (Canola oil) -10 98 Cotton seed oil -1 105 Sunflower oil -17 125 Soybean oil -16 130 Tung oil -2.5 168 Linseed oil -24 178 Sardine oil -28 185 PoppySeed oil -18 140 In accordance with present invention the first and second triglyceride oils are blended in a proportion of from 70:30 to 75:25 by volume. The exact ratio may vary as between different first and second triglyceride oils but, in general, the higher the IV of the, or each, second triglyceride oil the higher the proportion of the, or each, first triglyceride oil that should be used. In this regard it is believed to be beneficial that the relatively high IV oil component is diluted with relatively low IV component.

In a preferred embodiment the blend of triglyceride oils is made up of Canola oil (IV from 97-110) and Poppyseed oil (IV from 130-145) at a ratio of 3:1 by volume. For each oil a range of iodine values is quoted since the exact iodine value may vary slightly as between different sources of the oil. These oils are readily available in certain locations.

For example, Canola oil is widely produced and used in Canada and its popularity is increasing in Tasmania (Australia). Canola oil has been found to be lower in saturated fats (its content is about when compared with other oils. Biodiesel produced from these oils has been found to have an IV of 100-115.

The following table lists the properties of Canola oil useful in practice of the present invention.

Specific gravity 25°C ASTM D 4052 0.916-0.921 Iodine value ASTM D 1959-97 97 110 Saponification value ASTM D5558-95 188- 198 Free fatty acids ASTM D5559-95 2.5 mL of 0.02 N NaOH Peroxide value ASTM D3703 5.0 meq/kg AOM stability ASTM D 6186-98 15 hours min Smoke point ASTM D1322 230 °C Flash point ASTM D56 2900 330 0

C

Poppyseed oil may be obtained by pressing and/or extracting the seeds of poppies (Popaverls somniferum). Many cultivation areas for poppies are in India, Asia Minor and the Balkans. The production of Poppyseed oil is also increasing in Tasmania (Australia) where the annual production is estimated to be 9 million litres.

The following table shows the typical properties of Poppyseed oil useful in practice of the present invention.

Density (25 0 C) ASTM D 792 0.920-0.925 Iodine Value ASTM D 1959-97 135-145 Stearic Acid (C18) ASTM 256-90 max. Refractive Index (40 0 C) ASTM D 542 1.473-1.478 Acid Value ASTM D 2076-92 max. 0.4 Saponification Value ASTM D5558-95 189-198 Saturated Fatty Acids (C16) ASTM D 6157-2 8.0-12.0% Oleic Acid (C 18:1) ASTM D5559-95 12.0-22.0% Linoleic Acid (C18:2) ASTM D5559-95 62.0-75.0% Linoleic Acid (C18:3) ASTM D5559-95 max. 0 In forming the blend of triglyceride oils used in the present invention it has been found to be advantageous to mix the individual oil components at elevated temperature, for example, from 40-80 0 C. This is believed to benefit formation of a homogenous blend.

S"Conventional mixing apparatus may be used. When a 3:1 mixture of Canola oil and t Poppyseed oil is used, the temperature is preferably from 40-60'C.

In an embodiment of the invention it may be desirable to incorporate in the blend of oils one or more antioxidants. The intention here is to reduce the inherent capacity for oxidation of oil components in the blend. This may help to prevent formation of 00 undesirable oxidation products when the biodiesel is used. Conventional antioxidants may be added to individual oil components used to formulate the triglyceride blend or to the blend when it has been formulated. The amount of antioxidant required may vary as between different triglyceride oils and blends and can be optimised through S 10 experimentation. In the preferred embodiment described herein antioxidant is preferably incorporated in the Canola oil component prior to blending with Poppyseed oil. Here it has been found that antioxidants 302 and 306 are useful at a concentration of up to about by volume based on the volume of the blend. Antioxidant 302 comprises calcium ascorbate. Antioxidant 306 comprises mixed tocopherols (vitamin Both are commercially available.

Subsequent to formation, the blend of triglyceride oils is reacted (transesterification) with an alcohol in the presence of a catalyst. Typically, the alcohol is methanol or ethanol. The catalyst is usually an alkali metal hydroxide, such as sodium or potassium hydroxide. Potassium hydroxide has been found to most suitable when the alcohol is ethanol.

Usually, the oil blend to be reacted with the alcohol is free of water since the presence of water can cause problems with soap formation and with the separation of glycerin downstream. Any water present in the oil blend, or individual oil components of the blend, may be removed by conventional techniques, such as by heating.

In an embodiment of the invention the alcohol and catalyst are mixed prior to contacting with the triglyceride oil blend to form an alkali metal alkoxide. This may be carried out in a reactor provided upstream from the reactor in which the blend and alcohol/catalyst are to be contacted and reacted. Alternatively, the alcohol and catalyst may be contacted in a reactor into which oil blend is introduced.

For the (transesterification) reaction the blend is preferably provided at elevated temperature, for example, at from 40-80 0 C. Energetically, since the blend itself is preferably formed at elevated temperature, it may be desirable to transfer the blend for -7- V reaction immediately it has been prepared. In practice the temperature of the blend for reaction is an optimised temperature. If the temperature is too low the rate of reaction will be undesirably slow with detriment to productivity. On the other hand, if the temperature e¢3 I is too high, the method will be uneconomic due to energy considerations. For the preferred Canola oil/Poppyseed oil blend, the preferred reaction temperature is from 40-60C.

00oO i Depending on a temperature the reaction takes up to 8 a number of hours.

In the reaction alcohol (or alkoxide as the case may be) reacts with the oil blend to form mono-alkyl esters (biodiesel) and glycerin. The reaction is reversible so the 0alcohol/alkoxide should be used in a stoichrometric excess in order to drive production of ,I 10 mono-alkyl esters. In accordance with the present invention the alcohol is preferably used in a 50% excess of the stoichrometric amount.

A successful transesterfication reaction is signified by formation of separate layers of mono-alkyl esters and glycerin, the heavier co-product glycerin separating below the mono-alkyl esters. This glycerin may be separated and sold as is or purified for use in other industries, such as the pharmaceutical and cosmetics industries. The reaction should result in at least 96% ester content, and the extent of reaction can be determined experimentally as required.

Once the reaction is complete two major phases exist, i.e. biodiesel (mono-alkyl esters) and glycerin. Each phase will include impurities (primarily the alcohol used) and the reaction mixture may be neutralised at this stage by conventional techniques. The more dense glycerin may be drawn off from the bottom of the reactor/settling vessel used.

A centrifuge may also be used to speed up separation of the two phases.

Once the two phases have been separated excess alcohol can be removed by conventional techniques, such as flash evaporation or distillation. It is possible however for the alcohol to be removed and the post-reaction mixture neutralised before the esters and glycerin are separated. In either case, the alcohol that is recovered may be re-used. In this case, and as noted earlier, care must be taken to ensure that the alcohol is free from water.

The glycerin by-product contains unused catalyst and soaps that may be neutralised with an acid and sent to storage as crude glycerin. In some cases the salt formed during this phase is recovered for use as fertiliser. In most cases the salt is left in the glycerin. Water and alcohol are removed to produce 80-88% pure glycerin that is ready to be sold as crude glycerin. In more sophisticated operations, the glycerin may be distilled to 99% or higher c purity and sold into the cosmetic and pharmaceutical markets.

Once separated from the glycerin, the biodiesel (esters) may be purified by washing gently with water to remove residual catalyst or soaps, dried, and sent to storage. The time taken for a biodiesel-water emulsion to separate as biodiesel and water is typically a 00 ,i number of days and this can slow productivity significantly. Some impurities get washed away with water. One of the established washing methods is the so-called bubble method, where air is bubbled through the emulsion. As the air bubbles rise, they gain a thin coat of water which they then carry with them on their upward journey through the emulsion.

S 10 Hitting the air at the top of the settling tank, the bubbles pop and the water they brought to the surface slowly sinks again. On the way up and on the way down, the water collects glycerin, methanol, and resident water, all of which are polarised molecules and therefore water-soluble. Excess methanol evaporates at the top of the tank and the sinking water droplets collect more particles and glycerin to be deposited at the bottom. Typically, this process takes about 12 hours after which time the fuel phase is transferred into a settling tank. With conventional methods of producing biodiesel, storing the biodiesel in settling tanks for no less than a week is an important step. During this period the fuel is subjected to solar heat and gravity. Any remaining impurities settle to the bottom of the tank over time. The finished biodiesel is then pumped from the top of the tank through a suitable filter, e.g. a 51gm filter. Conventional production in this way typically totals a full seven and half days from washing to 'ready to use' biodiesel.

In accordance with an aspect of the present invention it has been found possible to accelerate the settlement process by addition of a demulsifier in the biodiesel-water emulsion. It has been found particularly useful to use the demulsifier BreakClear (available from Fueltreat Australia Pty Ltd). The demulsifier is used in an amount of for a litre of oil mixture. Use of the demulsifier can increase productivity significantly (by up to 3 times).

Once the biodiesel has been washed and separated it may still be necessary to remove residual water. For small quantities of biodiesel (lab scale 1-2 litres) residual water may be removed by heating to 80-100°C. For larger quantities of biodiesel heating is not practical and in this case the biodiesel may be drained through a mesh of a suitable 00

IO

O

water absorbing material. In practice of the present invention it has been found especially useful to drain the biodiesel through a mesh of anhydrous sodium sulphate.

Prior to use as a commercial fuel, the biodiesel must be analysed to ensure that it meets required specifications. The most important characteristics of biodiesel to ensure trouble free operation in a diesel engine are: Complete transesterification reaction; Removal of glycerin; Removal of catalyst; and Removal of alcohol.

0 The following table lists the properties required of biodiesel to meet the current Australian standard.

Property ASTM Method Limits Units Flash Point D93 130 min. Degrees C Water Sediment D2709 0.050 max. vol.

Kinematic Viscosity, 40 C D445 1.9 6.0 mm /sec.

Sulfated Ash D874 0.020 max. mass Sulfur D5453 S 15 Grade 15 max. ppm S 500 Grade 500 max.

Copper Strip Corrosion D130 No. 3 max.

Cetane D613 47 min.

Cloud Point D2500 Report Degrees C Carbon Residue 100% sample D4530** 0.050 max. mass Acid Number D664 0.80 max. mg KOH/gm Free Glycerin D6584 0.020 max. mass Total Glycerin D6584 0.240 max. mass Phosphorus Content D 4951 0.001 max. mass Embodiments of the present invention are illustrated in the following non-limiting Example which illustrates the method of the present invention. In the Example, reference is made to Figures 1 to 4. These figures illustrate apparatus suitable for putting the present invention into practice The following key lists various components referred to in the Figures. Other components are referred to in the following examples.

Key N1 Bottom outlet N2 Water inlet N3 Thermowel N4 Pressure indicator Air inlet N6 Liquid inlet N7 Thermowel N8 Liquid inlet N9 Safety valve Biodiesel inlet N11 Spare N12 Biodiesel outlet Methanol flow Biodiesel flow Glycerine flow Water flow Air flow Example 1 Preparation of potassium methoxide (Figure 1) The valve on nozzle N1 of the catalyst reactor, CR-102, is closed.

200 ml of 99% pure methanol (per litre of oil mix to be used) is fed into the catalyst reactor CR-102 through line 50-MET-01-CS, through nozzle N6. This amount is 60% more than the stoichiometric amount of methanol required for reaction with the oil blend to be used. The valve in the line is then closed.

The bottom valve on nozzle N1 and the valve in line 50-MET-04-SS on nozzle -11 are opened. Pump P-102 is started.

ct* The quantity of KOH required as per free fatty acids in the oil is 4.9mg per litre of oil mix. Through nozzle N11, 4.9-5.0 gms of KOH for every litre mixture of oil are C1 slowly added.

After all KOH has been added the pump is run for a further 15 minutes.

00 Cl This process will take around 1 hour for large quantities exceeding 10,000 litres.

O

S(b) Reaction of oil blend (Figure 2) The valve on nozzle N1 of the catalyst reactor, BR-103, is closed.

,I 10 For a successful reaction the oil must be free of water. To do this the oil is heated to 80 0 C, with this temperature being maintained for 15 minutes. The oil is then poured and allowed to settle into a settling tank for at least 4 hours.

Catalyst from CR-102 is pumped using pump P-102 to the heated oil through line 50-MET-03-SS.

The valve at the bottom of BR-103 on nozzle N1 and the valve on line 50-BIO-09- SS are opened and the pump P-103 started.

The mixture is stirred for an hour and then mixing is stopped.

Settling Tank (Figure 3) The mixture is transferred to settling tank ST-103 from BR-103 using pump P-103.

The mixture is allowed to settle for 8 hours.

Glycerin separates as a higher density by-product at the bottom of ST-105 Crude glycerin is pumped out using P-105. The settled biodiesel is pumped into the subsequent washing and settlement tank WT-107.

Washing and settlement in (Figure 4) The washing tank WT-107 is designed to wash and settle the biodiesel. The bottom valve on nozzle N1 is opened and an equal amount of water is added to the biodiesel mix. Both the water and biodiesel are initially kept at the same (room) temperature.

Using pump P-107, the mix is circulated through the pipe for 1 hour.

The bubble wash method is then applied. Air is pumped from air compressor P- -12- 101, through a perforated ring assembly at the bottom of the tank. This is done for S2 hours minimum. The mixture turns white as an emulsion is formed. The mixture is then heated to 60 0

C.

C When the temperature reaches constant 60 0 C 1 Oml/litre of BreakClear (demulsifier) is added to the mix and via air compressor P-101, a further 1 hour of

O

C mixing is carried out.

O The demulsifier accelerates the separation of biodiesel from the emulsion. The biodiesel is allowed to stand for about 8 hours in a storage tank and used only Swhen it becomes crystal clear. By adding the commercially available BreakClear CK, 10 50, demulsifier, the entire process is accelerated 3 times, hence the productivity is improved by three times.

The resultant mixture consists of 3 layers: a bottom layer of water; a middle layer of soap; and a top layer of washed biodiesel.

For small quantities of biodiesel (1-2 litres) heating to 80-100 0 C may be undertaken to remove any residual water.

For large quantities, the biodiesel may be drained through a mesh of anhydrous sodium sulphate to absorb any residual water.

The example was repeated and the biodiesel produced was found to have the following characteristics.

Sample Kinematic pH Value Density Calorific Flash Point Viscosity Kg/m 3 Value Deg centigrade mm 2 /s Mj/kg 1 4.5 6.9 870 40.3 132 2 4.3 7.0 869 41.4 138 3 4.7 6.5 880 40.9 142 4 5.1 6.3 885 41.2 144 4.7 6.8 864 40.7 142 6 4.6 6.8 872 41.0 140 7 4.9 6.5 874 40.8 135 8 4.8 6.7 869 41.0 141 9 4.4 7.0 877 40.8 141 -13- Example 2 Manufacturing process for 1000 litres of Biodiesel STEP 1: Methanol Quantity: e¢3 The stoichiometric quantity is usually 12.5% of methanol by volume of vegetable oil, that is, 125 millilitres of methanol per litre of oil. Excess Methanol is needed, to 00oO i achieve 98% conversion and usually 60% of the stoichiometric amount for fresh vegetable 0 oils (FVO). Therefore, for stoichiometric ratio of the 12.5% oil, that is 125 ml of methanol per litre of oil, the excess would be 75 ml, for a total amount of methanol of 200 ml per Slitre ofoil. Oils with higher molecular weights need higher excesses.

S 10 For fresh oils 60% through 70% excess is used. For tallow higher excesses are used. If care is taken with the titration and accurate measurements these instructions should result in a good, clean split, with esters on top and the glycerine and free fatty acids cleanly separated at the bottom.

If the biodiesel formed has problems in washing, with a lot of froth, this indicates the transesterification process is incomplete and unconverted material is forming emulsions.

The catalyst used is Potassium Hydroxide (KOH, Caustic Potash). It is hygroscopic, and absorbs water from the atmosphere. It usually comes in three grades: flakes and 5mm pearls 85% or half-pearls are 96-97%, small pearls (1-2 mm) are 99%. Use 9.0gms for 99%, 11.7gms for 95% and 15gms for 85% purity KOH.

CATALYST REACTOR CR-102 Preparation of Potassium Methoxide (Figure 1) 1. The valve on nozzle N I of the catalyst reactor, CR-102, is closed.

2. 220 litres of 99% pure Methanol is added to the reactor CR-102 through line MET-01-CS, through nozzle N6. The valve in the line is then closed.

3. The bottom valve on nozzle N1, and the valve in line 50-MET-04-SS on nozzle NIO are opened. Pump P-102 is started. The quantity of KOH required as per free fatty acids in the oil is checked. (It is described below under Catalyst). Through nozzle N11, 840 quantity of KOH are added slowly.

4. After all is added the pump is run for a further 15 minutes. The activity should take around 1 hour. The temperature of the mixture rises by 5 to 6 degrees C, which is normal.

-14- BIODIESEL REACTOR BR-103 (Figure 2) S1. The valve on nozzle N1 of the catalyst reactor, BR-103, is closed.

2. The used cooking oil is filtered first. For a successful reaction the oil must be free ¢€3 N, of water. Here are two methods of removing water.

Settling the water out: This method saves energy. Heat the oil to 60 C, maintain 00 CK, the temperature for 15 minutes and then pour the oil into a settling tank. Let it settle for at least 12 hours. Make sure you never empty the settling vessel more than Boiling the water off: Less-preferred method as it uses more energy and helps Sto form more FFAs in the oil. Heat the oil to 100 C. As the heat rises water separates out and falls to the bottom, drain it off to avoid steam explosions. Maintain the temperature until no more steam bubbles rise.

3 The volume of oil fats to be processed is measured and added through lICS.

4 The oil is heated to 500 C to make sure that all solid fats are melted.

5 Half the quantity of methanol from CR-102 is pumped using pump P-102 to the heated oil through line 50-MET-03-SS.

6 The valve at the bottom of BR-103 on nozzle N1 and the valve on line 50-BIO-09- SS are opened and the pump P-103 started. Mixing takes place for 5 minutes after which the mixture becomes murky because of solvent change. The temperature is maintained lower than 50 C.

7 The temperature at 600 C is maintained for one hour and heating is stopped (if it is on).

8 The unheated mixture is stirred for another hour, a total of two hours, then mixing is stopped. The mixture is allowed to sit for at one hour. The glycerine is then separated (drained).

9 The mixture is heated to 55 C and maintained for the whole reaction.

The second half of the prepared sodium methoxide to the heated mixture and mixed for one hour.

11 The mixture is then allowed to settle for one hour and transfered to settling tank ST-105 using pump P-103 through the line 50-BIO-10-SS.

SETTLING TANK ST-105 (Figure 3) 1 The mixture is allowed to settle overnight and glycerin drained from the bottom c valve on nozzle N1, using pump P-105. Care must be taken as the glycerin is quite hot and caustic.

C' 2 After all the glycerin has been removed, through nozzle N12, and using pump P- 104, through pipe line 50-BIO-16-SS, all of the biodiesel is pumped to washing 00 ,i tank WT-107 already containing 300 litres of water.

WASHING TANK WT-107 (Figure 4) 1 The bottom valve on nozzle N1 is opened, 300 litres of water are added. The water 10 and biodiesel are roughly at the same (room) temperature. 50ml of Breakclear-50 is added.

2 Using pump P-107, through the pipe line 50-BIO-19-SS, the mixture is recirculated for 1 hour.

3 The bubble wash method. Air is pumped from the Air Compressor P-101, through a perforated ring assembly at the bottom for 4 hours minimum. The pump P-107 and air compressor P-101 are turned off and the mixture allowed to settle for half an hour. The water falls to the bottom, turning completely white, and the fuel will be much lighter in color now. Water is drained and the process repeated two more times. The biodiesel is removed from the vessel, taking care not to contaminate it with any water.

4 The solution is heated to 60 degrees and passed through an anhydrous Na 2 S0 4 mesh to absorb any residual water.

Alcohol: Methanol, as near to absolute as possible, should be used. As with the oil, the water affects the extent of conversion enough to prevent the separation of glycerin from the reaction mixture.

Reclaiming excess methanol: Depending on the kind of oil used, it takes from 110- 160 millilitres of methanol per litre of oil to form methyl ester molecules. An excess of methanol also needs to be used to push the conversion process towards completion, the total used is usually 20% and more of the volume of oil used, 200 ml per litre or more.

Much of the excess methanol can be recovered after the process for reuse, simply by boiling it off in a closed container with an outlet leading to a simple condenser. Methanol boils at 64.7 C, though it starts vaporising well before it reaches boiling point. Unlike ethanol, methanol does not form an azeotrope with water and relatively pure methanol can be recovered, pure enough to reuse in the next batch. Methanol can be recovered at the 1 -16-

\O

end of the process, or just from the glycerine by-product layer, since most of the excess methanol collects in the by-product and it's that much less material to heat.

0 Cc The temperature should start at 65 to 70 C, as the proportion of methanol left in the by-product mixture decreases, the boiling point will increase, so the temperature needs 0 oO 5 to be raised to keep the methanol vaporizing, perhaps to as high as 100 C or more. It is possible to recover close to 95% of methanol used.

Throughout this specification and the claims which follow, unless the context INO requires otherwise, the word "comprise", and variations such as "comprises" and S"comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

Claims (1)

17- O THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS: 1. A method of producing biodiesel, which method comprises: C forming a blend of triglyceride oils comprising a first triglyceride oil having an iodine value of from 30-110 and a second triglyceride oil having an iodine value of 130- 00 0 145, wherein the first and second triglyceride oils are selected such that the difference in Stheir iodine values is from 40-80 and wherein the ratio by volume in the blend of the first triglyceride oil to the second triglyceride oil is from 70:30 to 90:10; reacting the blend of triglyceride oils with an alcohol in the presence of a CN 10 catalyst to form mono-alkyl esters and glycerin; separating the mono-alkyl esters and glycerin; and removing residual alcohol from the mono-alkyl esters to produce biodiesel. 2. A method according to claim 1 wherein the ratio by volume in the blend of the first triglyceride oil to the second triglyceride oil is 3:1. 3. A method according to claim 1 or claim 2 wherein the blend comprises up to 5% by volume of an antioxidant. 4. A method according to any one of claims 1 to 3, wherein the first triglyceride oil is Canola oil and the second triglyceride oil is Poppyseed oil. A biodiesel when produced by the method of any one of claims 1 to 4. DATED this 23 rd day of May, 2006 The University of Tasmania By DAVIES COLLISON CAVE Patent Attorneys for the Applicant