Biodiesel Production by Ethanolysis of Various

Biodiesel Production by Ethanolysis of Various Vegetable oils Using Calcium Ethoxide as Solid Base Catalyst

G. Anastopoulos*,G.S. Dodos*, S. Kalligeros††, F. Zannikos* *Fuels & Lubricants Laboratory, School of Chemical Engineering, National Technical University of Athens, 9 Iroon Polytechniou, Athens 157 80, Greece Tel. +30 2107723213, Fax. +30 2107723163, Email: [email protected] ††

Hellenic Naval Academy, Fuels & Lubricants Technology Laboratory, End of Hatzikiriakou Avenue, Piraeus 18539, Athens Greece Tel. +302104581656, Fax. +302104581656 Email: [email protected] (Corresponding author)

Abstract In this study, fatty acid ethyl esters (FAEE) were produced from 4 different vegetable oils (sunflower, cotton seed, olive oil and used frying oil) using calcium ethoxide as a heterogeneous solid base catalyst. The ester preparation involved a two-step transesterification reaction, followed by purification. The effects of the mass ratio of catalyst to oil, the molar ratio of ethanol to oil, and the reaction temperature were studied on conversion of sunflower oil to optimize the reaction conditions in both stages. The rest of the vegetable oils were converted to ethyl esters under optimum reaction parameters. The optimal conditions for first stage transterification were an ethanol/oil molar ratio of 12:1, catalyst amount (3.5%), and 80 °C temperature, whereas the maximum yield of ethyl esters reached 80.5%. In the second stage, the yield of ethyl esters showed signs of improvement of 16% in relation with the onestage transesterification, which was obtained under the following optimal conditions: Catalyst concentration 0.75% and ethanol/oil molar ratio 6:1. Property analysis of prepared ethyl ester samples was done, in order to examine their quality parameters.

The results obtained showed that the density, viscosity and calorific value of the produced ethyl esters had values close to those of a no. 2 diesel. On the contrary, the cold filter plugging points were higher than the conventional diesel fuel.

Keywords: Fatty acid ethyl esters, Transesterification, Biodiesel, calcium ethoxide, FAEE properties

1.

Introduction

Recently, the world importance of biodiesel production has significantly increased. The decrease of carbon dioxide emissions, the independence from imported crude oil and better sales possibilities for farmers are some of the reasons of biodiesel importance. Transesterification is one of the most commercially useable methods to produce biodiesel and the process involves a reaction between ester (here triglyceride) and alcohol to form new ester and alcohol. In the transesterification of triglyceride to fatty acid alkyl esters three reversible reactions take place consecutively in which diglycerides and monoglycerides are major intermediate products (Zhang, 2003, Banerjee, 2009, Satyanarayana 2010, Fan 2010). A review by (Ma and Hanna, 1999) summarized the parameters that significantly affect on the rate of transesterification reaction which include reaction temperature, alcohol to oil molar ratio, catalyst concentration and type of catalyst. Transesterification can be performed at different temperatures, and the ester yields increase by rising the reaction temperature. However, if the temperature reaches to the boiling point of alcohol, a lot of alcohol's

bubbles are formed hence inhibit the mass transfer on the phase's interface (Meher, 2006, Puhan, 2007). Methanol is the most commonly used alcohol due to its low cost and physical and chemical advantages in the process (Van Gerpen, 2005). However, ethanol can prevail in regions where it is easily produced and available (Marjanovic, 2010). Its use can be more advantageous than the use of methanol, since it has a superior dissolving capability and is less toxic (Moser, 2009, Marchetti, 2007). There are also other advantages of using ethyl ester based biodiesel over methyl esters. Due to the extra carbon added, fatty acid ethyl esters have a higher heat content and cetane number and improved storage properties, as a result of lower cloud and pour points (Boros, 2009, Knothe, 2009, Foglia, 1997). The use of biodiesel composed of fatty acid ethyl esters is also more environmentally friendly due to lower emissions of nitrogen oxides and carbon monoxide (Makareviciene, 2003). Additionally, as most of the available methanol is derived from natural gas or from coal via synthesis gas, biodiesel produced from methanol cannot be considered entirely carbon–neutral as happens with the ethyl ester biodiesel that is totally derived from agricultural sources (Jones, 2010, Jones, 2009) . Most of the works already reported on the ethyl esters production, did not find a suitable process. In some cases, excess of anhydrous ethanol are used, such as ethanol/triglycerides molar ratio 6:1, which in volume it represents 36 v/v% (Issariyakul, 2007, Issariyakul, 2008, Nimcevic, 2000). Another alternative presented in the literature, is the use of a cosolvent such as tetrahydrofuran (Zhu, 2006), which has a negative effect in the economy of the process. There are several differences in the physicochemistry of the reacting system based on ethanol compared to methanol. For example, the higher mutual miscibility

between the glycerol and the esters in the presence of ethanol, severely complicate the phase separation operation after the reaction. Depending upon the ethanol/oil volume fraction loaded to the reactor, the phase separation may not occur, being necessary to add glycerol (Encinar, 1999, Encinar, 2002, Encinar, 2005) or to evaporate the ethanol (Bouaid, 2007) in order to induce phase separation. Another problem is the intensive soap formation that occurs in this system, and leads to the formation of stable emulsions that also complicates the separation of phases. Therefore, the washing procedure requires large volumes of water being necessary to improve this part of the process (Encinar, 2007). In this study, ethanolysis of 4 different vegetable oils (sunflower, cotton seed, olive oil and used frying oil) using calcium ethoxide as heterogeneous catalyst was conducted, in order to characterize the ethyl esters obtained for their applications as fuels in internal combustion engines. The driving force for this study was that for one reason the reaction of ethanolysis for the production of biodiesel, has rarely been studied, especially in heterogeneous catalytic systems, compared to the intensive studies undertaken on the methanolysis reactions. The second and most important reason why this study was undertaken came about as a result of the European Renewable Energy Directive which bans biofuels with a GHG savings of less than 60% by 2018. One of the tools to improve the GHG savings from Biodiesel is to replace methanol with ethanol. Finally, a further reason that this study was conducted was the M/393 Mandate of the European Commission to European Committee for Standardization (CEN) for the development of a European Standard for Fatty Acid Ethyl Ester (FAEE) to be used as a fuel for diesel engines. To briefly outline what the mandate entails it should be noted that the European market is

characterized by a significant and continuously growing demand for diesel fuel. Therefore the demand for diesel fuel type replacements is significant greater than that for gasoline. Bioethanol has been used in the European market mainly as ETBE (ethyl tert butyl ether) on the basis of the specifications of the Fuel Quality Directive 98/70/EC as it amended by the Directive 2009/30/EC. Although used in low blends (5%), as ETBE and E85, bioethanol still faces problems to penetrate the European market further. 2.

Experimental Section

2.1. Materials

The ethanol, calcium and analytical reagents (e.g., standards for GC analysis) were of high grade and were supplied from Sigma Chemical Co. Commercial grade olive oil was purchased from a local grocery store. Sunflower and cotton seed oil were obtained from Elin Biofuels S.A, while the waste vegetable oil used in this work was a mixture of olive oil and sunflower oil collected from local fast food restaurants. The 4 vegetable oils were used as received without further purification. Table 1 presents their major quality properties. The saponification value of the oils varied between 170.4 – 196.2 mg KOH/g, while water content lay in the range 274 – 1060 mg/kg. The average molecular weight of vegetable oils is calculated by MW = 56.1 × 1000 × 3/(SV–AV), where AV (mKOH/moil, mg/g) and SV is the saponification value (mKOH/moil, mg/g) (Zhu, 2006).

2.2.

Catalyst preparation

Calcium ethoxide was synthesized in a 250 mL glass reactor with a condenser. The magnetic stirring rate was 700 rpm. The reaction procedure was as follows: First, calcium was dispersed in ethanol under magnetic stirring. Then, it was heated to 65 °C by water circulation. The reaction can be expressed by the following equation:

65°C Ca + 2CH3CH2OH

Ca(OCH2CH3)2 + H2

After 8 h of reaction, ethanol was first distilled off under vacuum. Then, the catalyst was dried in an oven at 105 °C for 1 h.

2.3. Transesterification procedure

The transesterification reactions were carried out in a 500 mL glass spherical reactor, provided with a thermostat, mechanical stirring, sampling outlet, and condensation system. The procedure followed is described next. The reactor was preheated to 75 °C, to eliminate moisture, and then 250 g of each vegetable oil was added. When the reactor reached the temperature established for the reaction, the ethanol and the catalyst were added, in the amounts established for each experiment, and the stirring system was connected, taking this moment as time zero of the reaction. Each mixture was vigorously stirred and refluxed for the required reaction time. After the ethanolysis reaction finished, the excess ethanol was distilled off under vacuum (absolute pressure of 150 mm Hg) and Ca(OCH2CH3)2 catalyst was separated by centrifugation. The transesterification product was allowed to stand in a separating funnel for glycerol separation. Due to a strong emulsion in the case of ethanolysis products, glycerol was not separated only by gravity. In order to separate glycerol

from ethyl ester phase, approximately 10 g of pure glycerol was added into the transesterification product and the separating funnel was shaken vigorously and the product was allowed to stand. Glycerol layer separated from ester layer within an hour. The ethyl ester samples were analyzed in a HP 5890 gas chromatograph equipped with a flame ionization detector and a capillary column HP-INNOWAX (30 m × 0.15 mm × 0.2 μm). 4 μL of the upper oil layer were dissolved in 300 μL of nhexane and 100 μL internal standard solutions for GC analysis. Samples (1 μL) were injected by a sampler at an oven temperature of 220 °C. After an isothermal period of 4 min, the GC oven was heated at 10 °C /min to 230 °C, and held for 7.5 min. Nitrogen was used as carrier gas at a flow rate of 2 mL/min measured at 20 °C and as detector make up gas at a flow rate of 30 mL/min. The inlet pressure was 96.4 kPa. The split ratio was 10:1. The injector temperature and detector temperatures were 300 °C and 320 °C, respectively.

The FAEE yield in each experiment was calculated by the following expression:

where both mactual [g] and mtheoretical [g] are the masses of ethyl ester; Cester [g/mL] is the mass concentration of ethyl ester which was acquired by GC; n is the diluted multiple of ethyl ester; ρoil [g/mL] is the density of the vegetable oil.

3.

Results and Discussion

The 4 types of ethyl esters were prepared by using two-stage transesterification reaction. In both stages, the influence of various reaction variables on the conversion

of sunflower oil was examined in order to assess the optimal reaction conditions. In the first stage, the operation variables employed were ethanol/oil molar ratio (6:1– 15:1), catalyst concentration (0.5–4 % m/m), and temperature (70–90 °C). Oil mass, reaction time, and alcohol type were fixed as common parameters in all experiments. In the second stage the initial concentration of ethyl esters was 80.5 % m/m. Only two variables were studied: ethanol/oil molar ratio (4:1–8:1) and catalyst concentration (0.25–1 % m/m). The temperature (80 °C) was fixed as common parameter in these experiments.

3.1. Transesterification in one stage

Effect of Mass Ratio of Catalyst to Oil on Biodiesel Yield – The mass ratio of Ca(OCH2CH3)2 to sunflower oil was varied within the range of 0.5-4.0%. The ethyl esters yield increased with increasing calcium ethoxide, and a 81.8% biodiesel yield was obtained by adding 4.0% Ca(OCH2CH3)2 after a reaction time of 2.5 h (Figure 1). Therefore, with the addition of more catalyst, there was also the faster rate at which the reaction equilibrium was reached because of the increase in the total number of available active catalytic sites for the reaction. However, when the catalyst amount exceeded 3.0%, there was little impact on the biodiesel yield by increasing calcium ethoxide. The ethyl esters yield is determined by the surface reaction and the mass transfer. In this reaction, the optimum addition of catalyst is 3.0% by mass of oil. Effect of Reaction Temperature on Biodiesel Yield – Reaction temperature can influence the reaction rate and the ethyl esters yield because the intrinsic rate constants

are

strong

functions

of

temperature.

In

all

experiments,

an

ethanol/sunflower oil molar ratio of 12:1, and a catalyst concentration of 3 % m/m

were used. The reaction temperature was varied between 70 and 90 °C. Figure 2 shows the effect of the reaction temperature on the biodiesel yield. It indicates that the reaction rate was higher at high temperature than at low temperature. The ethyl esters yield was only 31.4 % at 70 °C after 2.5 h of reaction, and it reached to 80.5 % at 80 °C at the same reaction period. Therefore, the final ethyl ester concentration was almost reached in 2.5 h at 80 °C. After this initial period, there was a second period in which the composition evolved slowly towards equilibrium. The yields obtained in the 90 and 80 °C experiment were very similar, and the one in the 70 °C run was clearly less. Therefore, the equilibrium concentration was strongly conditioned by the temperature and favoured for the same; that is, the equilibrium concentration increased as the temperature increased. Effect of the Molar Ratio of Ethanol to Oil on Biodiesel Yield – Four experiments were carried out varying the ethanol/oil molar ratio between 6:1 and 15:1. According to the results of the previous sections, a catalyst concentration of 3 % m/m, was used. Temperature was fixed at 80 °C. Figure 3 shows the evolution of esters yield with the reaction time. As it can be observed, with a 6:1 molar ratio, the conversion to esters was near 56.4 % m/m after 4 h. The esters yield increased as the molar ratio increased, with the best results (80.5%) being for a molar ratio 12:1. Nevertheless, a later increase of molar ratio to 15:1 does not produce an increase in the yield, since a lower value is obtained (77.6%). This is motivated because for higher molar ratios the separation of the glycerol was difficult, since the ethanol excess hinders the decantation by gravity so that the apparent yield of esters decreases since part of the glycerol remains in the biodiesel phase. These results are similar to those obtained by (Feuge et al., 1949) in the ethanolysis of peanut oil, and (Freedman et al., 1984), and (Schwad et al., 1987) in the ethanolysis of sunflower oil. The excess

of alcohol seems to favor conversion of di- to monoglycerides, but there also is a slight recombination of esters and glycerol to monoglycerides since their concentration keeps increasing during the course of the reaction, in contrast with reactions conducted with low molar ratios (Fillieres et al., 1995). (Krisnamgkura et al., 1992) have observed that when glycerol remains in solution it helps to drive the equilibrium back to the left, lowering the esters yield. In consequence, the alcohol/oil molar ratio is one of the most important variables affecting the esters yield, and although the stoichiometric ratio for transesterification requires 3 mol of alcohol and 1 mol of triglyceride, an excess of alcohol is used in the practice. Hence, the alcohol molar/oil ratio is a variable that must be always optimized.

3.2.

Transesterification in two stages

In one-stage transesterification the maximum yield of sunflower ethyl esters was 80.5 % m/m. According to the standard EN-14214 the yield of ethyl esters should be 96.5%. Hence, after the transesterification in one stage, the biodiesel must contain unreacted vegetable oil in the form of glycerides. In accordance with the literature, in the final equilibrium of the transesterification reaction there are significant amounts of triglycerides, diglycerides, and monoglycerides (Fillieres et al., 1995). In this situation, the equilibrium can be shifted to the right by carrying out a multistage transesterification process. This idea is the basis of the industrial process, which is carried out in a two-stage reaction with separation of the glycerol after each stage. In our case, as it has been indicated, we started from oil with 80.5 % m/m ethyl esters, where the glycerol formed in the first stage was withdrawn. This reaction mixture contained ethyl esters and mono-, di-, and triglycerides. The process continued

aggregating ethanol and catalyst. The procedure used agrees with the previously described results. The variables studied were ethanol/oil molar ratio of the second stage (4:1, 6:1, and 8:1) and catalyst concentration of the second stage (0.25–1%). The temperature (80°C) remained fixed. Figure 4 shows the influence of catalyst concentration on the evolution of esters yield with time in the second transesterification stage. As it can be observed, the second stage gave rise to an increment in the yield of ethyl esters in relation to the equilibrium value of the first stage. The curves are similar to those of the first stage. In fact, there is a sharp increase in the first minutes, and after that the curves are asymptotic with time. The conversion was increased firstly with the increase of catalyst amount from 0.25 to 0.75%. But, with further increase in the catalyst amount the conversion was decreased, which was possibly due to a mixing problem involving reactants, products and solid catalyst. The maximum yield was 97.5 % m/m after a reaction time of 1.5 h and the concentration of the catalyst was 0.75%. However, the EN-14214 limit of 96.5%, which has been set as the acceptable limit for the ethyl esters yield, was achieved at the same catalyst concentration and a reaction period of 30 min. Therefore, the addition of ethanol, once the glycerol of the first stage was withdrawn, improved the yield and displaced the reaction equilibrium to the right. Figure 5 presents the influence of ethanol/oil molar ratio on the evolution of esters yield with time in the second transesterification stage. According to the experimental results when the ethanol amount was increased, the conversion was also increased considerably. At 80 °C, a conversion of 88.9 % m/m was reached in 30 min for the ethanol/oil molar ratio of 4:1, while for the same reaction period, the increase of molar ratio to 6:1 resulted in a 96.5 wt-% yield of sunflower oil ethyl esters, which satisfies the European specification in terms of total ester content. However, with

further increase in the molar ratio to 8:1 there was only little improvement in the conversion (96.8 % m/m). Thus, it can be concluded that an excess ethanol feed is effective in elevating in conversion only to certain extent. Figure 6 illustrates the conversion yield of the rest vegetable oils in both transesterification stages. It ought to be taken into account that the conversion procedure of vegetable oils to ethyl esters took place under the conditions which have already been outlined above. According to the experimental results, the yield rates which coincided with sunflower oil were also apparent in the cotton seed oil as well as in the olive oil. Particularly, the yield for the 1 st stage transesterification of cottonseed oil reached 81.6%, whereas, for the olive oil it was 80.3%. In the second transesterification stage of both vegetable oils the conversion yields increased even more; (more specifically, for cotton seed oil the yield was 96.9%, whereas for the olive oil it was 97.7%) as far as the content of the final reaction products in esters is concerned, satisfying the acceptable limit of 96.5%, set by European specifications. However, in the case of used frying oil, the yields in both transesterification stages seem to be less in comparison to those of the rest of the vegetable oils. For instance in the first transesterification stage the yield of the used frying oil ethyl ester was 77.6%, whereas, in the second stage the yield was 92.5%. This difference in yield could be attributed to the fact that there is a high concentration of water in used frying oil, which probably leads to the partial deactivation of the catalyst. This deactivation is possibly due to the parallel reaction between calcium ethoxide and the water, where the calcium ethoxide being a strong base retracts with a proton from the water thus forming ethanol. Having done a data analysis of the above outlined results, it can be concluded that the transterification process of vegetable oils to ethyl esters with the use of

calcium ethoxide as a heterogeneous catalyst is quite efficient. The advantages of this process include the high conversion yields, the sort time needed and the mild reaction conditions in comparison to the transterification procedures that use other heterogeneous catalysts (Suppes et al., 2004; Kim et al., 2004). An additional advantage of the calcium ethoxide is that there needs to be no calcination with air in high temperatures as it necessary in promoted inorganic metal oxides when used as catalysts in the transesterification process (Xie et al., 2006; Hattori, 2004; Zhu et al., 2006; Xie et al., 2006). This advantage in combination with the rest of the pros makes the transesterification process of vegetable oils using calcium ethoxide rather attractive for industrial application.

3.3.

FAEE properties

The four types of ethyl esters were studied in terms of their physicochemical properties so as to study whether their quality parameters where indeed within the European standard EN-14214. The results of analysis are given in Table 2. It is observed that three out of four types of ethyl esters do satisfy the European norm of viscosity. The ester which was different from the other three was the used frying ethyl ester, which appeared to be above the highest limit (5 cSt) of the european specification. On the other hand, each and every type of ethyl esters had a density within the range of 860 – 900 kg/m3. The results dealing with the gross calorific value showed that the ethyl esters of used frying oil have the lowest value, whereas the highest was yielded by the sunflower oil ethyl esters. It is important to mention that in the standard EN-14214, specifications concerning the HHV of a biodiesel do not exist, but considering that the HHV of the diesel fuel was about 46 MJ kg −1, the ethyl

esters contained approximately 10% less energy. The sulfur content was proven to be almost at zero for the four ethyl ester samples. Yet, the frying oil ethyl esters proved to be unsatisfactory in terms of EN-14214 specifications set to measure the content in water, as they surpassed 500 mg/kg. However, the other types seemed to be within the specification. The flash point for all samples was proved to be higher than 101 °C which has been set as a lowest limit by the European specification. The acid value of the esters with the exception of the used frying oil ethyl ester ranges within the limits specified by the standard (0.5 mg KOH/g). Also, the microcarbon residue is in accordance with the maximum required limits given in the EN-14214 (maximum 0.30 % m/m). In the standard EN-14214 the CFPP value is not specified, since it is different at each country. In the Mediterranean countries, the required limits for the CFPP of automotive diesel are announced as “Winter Grade” and “Summer Grade”. The required limit for “Winter Grade” is −10 °C, whereas for “Summer Grade” it is 5 °C (Mittelbach, 1996). The values of CFPP indicated in Table 2 ranged between −2 and 3 °C; in consequence the four types of ethyl esters produced can be used as substitutes for “Summer Grade” automotive diesel. A possible solution for the use as “Winter Grade” would be the use of CFPP depressants. Finally, the values of cloud and pour points in Table 2 are very high. For example, the cloud and pour points of typical diesel fuels were −2 and −16 °C, respectively. In general, as it can be observed, these parameters follow a parallel evolution with the CFPP. Therefore, the comments in relation to the CFPP also are applicable to the cloud and pour points. Mono- and diglycerides as well as triglycerides are referred to as bound glycerol. They are present in the feedstock oil and can remain in the final product in small quantities. A high excess of alcohol in the transesterification reaction should

ensure that all triglycerides (the major component of vegetable oil) are reacted. A higher content of glycerides in the ester, especially triglycerides, may cause formation of deposits at the injection nozzles and at the valves (Felizardo et al., 2006; Vicente et al., 2006). The GC analysis of the produced ethyl ester of sunflower, cotton seed oil, and olive oil showed that the triglycerides of the parent oils reacted at a satisfactory yield to mono- and diglycerides. Their values were found to agree with the specified EN 14214 limits. However, the content of individual glycerides (monoglycerides, diglycerides and triglycerides) found in used frying oil ethyl ester, were not within the three European specifications, which imply that the transesterification reaction was incomplete. Regarding the free and total glycerol contents, the measured values for sunflower, cotton seed oil and olive oil ethyl ester were found below the specification limits, while in the case of the used frying oil ethyl ester, the values were found to be higher than their parameter limits.

Conclusions The two-stage transesterification of 4 vegetable oils with ethanol was carried out using calcium ethoxide as solid base catalyst. In order to obtain biodiesel with high purity, the reaction conditions, such as catalyst concentration, reaction temperature and molar ratio of ethanol/oil, were optimized on the conversion of sunflower oil. The rest of the vegetable oils were converted to ethyl esters under optimum reaction parameters. The physicochemical properties of ethyl esters were determined as per the EN standards and procedures. The following conclusions can be drawn from this study:

 The calcium ethoxide is an active and promising heterogeneous catalyst for the production of ethyl esters.  The optimized reaction conditions for one stage transesterification of vegetable oils were a 12:1 molar ratio of ethanol to oil, the addition of 3.5% Ca(OCH2CH3)2 catalyst, a 80°C reaction temperature, and about 2.5 h of reaction time.  The two-stage transesterification improved the results obtained in the single-stage transesterification. An improvement of about 16% in relation with the one-stage transesterification, was obtained under the following optimal conditions: Catalyst concentration 0.75%, ethanol/oil molar ratio 6:1 and 30 min of reaction time.  The values of density, viscosity, and higher heating value of ethyl esters were similar to those of automotive diesel. However, the CFPP values were higher, which may conduce to potential difficulties in cold starts. On the other hand, the flash points, which were higher than those of diesel fuel constituted a safety guarantee from the point of view of handling and storage.

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Table 1. Physicochemical properties of vegetable oils.

Used

Sunflower

Cotton

Olive

oil

seed oil

oil

32.6

26.1

29.4

40.2

EN ISO 3104

921.7

914.6

908.2

926

EN ISO 12185

Flash point (°C)

272

246

268

286

EN 2719

Iodine number (cg I/g oil)

118

113.2

98

108

EN 14111

Acid value (mg KOH/g)

0.33

0.7

0.25

2.8

EN 14104

Saponification value (mg KOH/g)

192.1

195

196.2

193.2

AOCS CD3 1993

Water content (mg/kg )

347

512

274

1060

EN ISO 12937

Sulfur content (mg/kg)

0.23

3

2.6

5

EN ISO 20846

Pour point (°C)

-11

-8

-16

-15

ISO 3016

Carbon residue (% m/m)

0.03

0.05

0.09

0.18

EN ISO 10370

Average molecular weight (g/mol)

876

866

857

882

-

Property Kinematic viscosity (cSt, 40 °C) 3

Density (kg/m , 15 °C)

frying oil

Test method

Table 2. .Properties of fatty acid ethyl esters.

Ethyl ester type Property

EN 14214

Test method

Sunflower

Cotton

Olive

Used

oil

seed oil

oil

frying oil

Density (kg/m , 15 °C)

882.7

881.2

881.5

888.5

860-900

EN ISO 3675

Kinematic viscosity (cSt, 40 °C)

4.63

4.52

4.88

6.19

3.50–5.00

EN ISO 3104

Flash point (°C)

175

184

182

188

120 min

EN ISO 2719

Sulfur content (mg/kg)

2.2

3

2.5

4.7

10 max

EN ISO 20846

Nitrogen content (mg/kg)

7

14

4.8

2

-

ASTM D 4629

Phosphorous content (mg/kg)

4

6

3

5

10 max

EN 14107

Water content (mg/kg )

154

189

208

376

500 max

EN ISO 12937

Acid value (mg KOH/g)

0.15

0.45

0.19

2.4

0.5 max

EN 14104

Iodine number (cg I/g oil)

118

112

98

108

120 max

EN 14111

Cloud point (°C)

1

1

7

8

-

EN 23015

Pour point (°C)

-6

-8

-6

-1

-

ISO 3016

CFPP (°C)

-3

-4

-2

3

+5 max

EN 116

1A

1A

1A

1A

-

EN ISO 2160

Sulfated ash content (% m/m)