PURIFICATION AND PHYSIO-CHEMICAL CHARACTERIZATION OF GLYCEROL BY-PRODUCT OF PALM OIL BIODIESEL INDUSTRY AS POTENTIAL BASE

FLUID FOR SYNTHETIC OIL-BASED DRILLING FLUID SYSTEM

Marbun, B. T. H*, Hutapea, P. A, Aristya, R, HusinDepartment of Petroleum Engineering, Institut Teknologi Bandung, Bandung, West Java, Indonesia

bonar.marbun@tm.itb.ac.id, philiphutapea@ymail.com, ramadhana.aristya@yahoo.com, husin_aidid@yahoo.com

Abstract:

The development of an OBM from glycerol was carried out in this work. Glycerol used in this study, which is by-product of palm oil biodiesel industry, is a new alternative for OBM. In this study, crude glycerol will be purified using H3PO4 solution to increase the purity of glycerol from about 50% to more than 80% (Farobie, 2009). The characterization of glycerol properties include chemical compound, density, flash point, pour point, and cloud point.

The preliminary tests result indicates that purified glycerol can be used as synthetic OBM in accordance with the API standard and also can become the reference for this synthetic OBM development which is very potential due to its environmentally friendly characteristics and since it may be derived from the abundant and low cost raw materials from by-product of biodiesel production.

Keywords: Glycerol, purification, synthetic oil-based mud

1. Introduction

1.1. Palm oilPalm oil has fatty acid content varies with carbon chain lengths ranging from C12 to C20 carbon atoms. Fatty acid composition determined the physical and chemical properties of palm oil [1]. Palm oil has a major component in the form of triglycerides by 94%. In addition, palm oil also contain fatty acids by 3-5% and the non-trigliserida by 1% called minor components such as carotenoids, tocopherols, tocotrienols, sterols, phospatida, and aliphatic alcohols. Palm oil fatty acid composition is presented in Table 1.

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Table 1 Composition of Fatty Acid in Crude Palm Oil [2]

Fatty Acid Carbon Chain Content (%) Melting Point (°C) Saturated Fatty Acid

Capric Acid (C10:0) 10:0 1-3 31.5Lauric Acid (C12:0) 12:0 0-1 44Myristic Acid (C14:0) 14:0 0.9-1.5 58Palmitic Acid (C16:0) 16:0 39.2-45.8 64Stearic Acid (C18:0) 18:0 3.7-5.1 70

Unsaturated Fatty AcidOleic Acid (C18:1) 18:1 37.4-44.1 14Linoleic Acid (C18:2) 18:2 8.7-12.5 -11Linolenic Acid (C18:3) 18:3 0-0.6 -9

1.2. GlycerolGlycerol is a liquid that is colourless, odorless and is a viscous liquid that has a sweet taste [3]. The molecular formula of glycerol is C3H5(OH)3 (Figure 1) with the chemical name 1,2,3-propanetriol [4]. The properties of glycerol are soluble in water easily, increasing the solution viscosity, water binding and lowered water activity.

Figure 1 Visualization of molecular and molecular formula of glycerol [5]

This compound is soluble in water and dissolved in alcohol. It can be dissolved in a solvent such as ether and ethyl acetate, but insoluble in hydrocarbons. The characteristic of glycerol is showed in Table 2.

Table 2 Characteristic of glycerol [6]

Parameter Value/CharacteristicCAS numberMolecular formulaMolar massPhaseColour

56-81-5C3H8O3

92.1 g mol-1

FluidColourless

Tovbin et al (1976) [7] explain that the production of glycerol from fat can be done through three methods, such as transesterification, saponification and hydrolysis. The result of this methods produced crude glycerol compounds which are still a lot of containing impurities particle such as residual catalyst and free fatty acids.

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This study described the preliminary test of glycerol by-product of palm oil biodiesel industry as the potential base fluid for synthetic-based drilling fluid system. The developments of glycerol utilization were to make it as base oil drilling mud for oil-based mud and lubricity for water-based mud.

1.3. BiodieselBiodiesel made from vegetable oil also has a lower cetane number than petrodiesel so that power can be generated lower. The characteristic differences can be solved by esterification process. One of vegetable oil that developed to biodiesel was derivative products by palm oil. According to Hambali (2013) biodiesel is defined as the methyl ester as produced from vegetable oils or animal fats and qualified to be used as fuel in diesel engines. Chemically, biodiesel is derived from a group of lipid monoalkyl esters of fatty acids with 12-20 of carbon chain length.Physio-chemical properties of biodiesel are similar to diesel fuel (petrodiesel), but in some case biodiesel is more desired. Biodiesel has the environmentally friendly nature as compared to petrodiesel because biodiesel contained no sulfur and benzene.

1.4. Crude glycerol In this study, crude glycerol is derived from transesterification process. In the transesterification of palm oil, triglyceride is reacted by alcohol with the help of strong acid or strong base. The resulting product is a methyl ester or biodiesel and glycerol as a by-product (Figure 2).

Figure 2 Transesterification process of palm oil to biodiesel and glycerol [8]

Glycerol used was crude glycerol which is a by-product of palm oil biodiesel industry that has purity 50% that derived from transesterification process. Glycerol was a by-product of biodiesel production that has the highest number compared with the other side. Amount of glycerol produced from each biodiesel production approximately 10% of the total production of biodiesel [9]. This crude glycerol still contains residual methanol, residual catalyst, and impurity materials derived from oil as biodiesel raw materials.

2. Methods

2.1. Transesterification of Palm OilGlycerol to be used in this study is a by-product of the production of methyl esters (biodiesel). Glycerol is obtained by a process of transesterification, the process of triglycerides to alcohol reaction using base catalyst to produce alkyl esters of fatty acid and glycerol. In the trans-esterification process, methanol is added as much as 15% (v/v) of the total raw materials of olein/stearin oil to be processed and mixed with KOH as much as 1% (v/v) of the total raw materials olein/stearin oil to be processed to form methoxide solution. Then, olein/stearin oil and mixed with a solution of methoxide transesterification reactor. Transesterification process is be held for 1 hour and stirred at a temperature of 55 oC by 100

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rpm. Settling process is then performed to separate the crude methyl ester and crude glycerol produced.

Figure 3 Diagram of Transesterification Process

Figure 4 The result of Transesterification Process [10]

2.2. Purification of Crude GlycerolCrude glycerol by-product of palm oil biodiesel industry was still many impurities found (Figure 5). Common impurities in crude glycerol are non-reacting methanol, soap, and potassium hydroxide catalyst [11], [12]. Therefore, purification process is required to reduce any unwanted chemical compound.

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Figure 5 Crude Glycerol as a Side Result from Palm Oil Biodiesel Production

Farobie (2009) used crude glycerol derived from Jatropha’s biodiesel production in his thesis which has glycerol content was 40.19%. The purification method based on Kocsisová and Cvengroš Cvengros (2006) method to obtain the result of glycerol content was 82.15%. Based on this method, crude glycerol is added by phosphoric acid 5% (v/v). Then, the solution was stirred using a magnetic stirrer for 30 minutes. Solution formed is waited to separate for 60 minutes.

In this study, the separation of this impurities compound from glycerol is able to be done by adding phosphoric acid and stirring by low RPM mixer. Initially, the phosphoric acid that was used is a solid phase (Figure 6 A).

Then, phosphoric acid solid is added water to be changed in solution (Figure 6 B). Phosphoric acid solution has 85% concentration. Then, crude glycerol was added by this phosphoric acid 5% (v/v).

Figure 6 Phosphoric acid solid phase (A) and Phosphoric acid solution (B)

This acid will react with residue of potassium hydroxide catalyst and form potassium phosphate salt (Figure 7 A). Furthermore, phosphoric acid will modify the soap into free fatty acid (Figure 7 B).

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(A)(B)

Figure 7 Reaction of (A) Potassium Phosphate Salt and (B) Free Fatty Acid Formation [10]

Based on this research, the increase of phosphate acid in crude glycerol forms 3 layers with mass distribution percentage as follows:

a. Upper layer (FFA), solid phaseb. Middle layer (glycerol), liquid phasec. Lower layer (K3PO4 salt), solid phase

The layers formed by adding phosphate acid are shown in Figure 8, after the mixture is settled within one hour at room temperature.

Figure 8 Three Layers Formed after Adding Phosphate Acid

The separation of glycerol layer from K3PO4 salt and FFA is done by screening using decantation method combined with 200 mesh funnel while giving flow space from the FFA solid. At the screening process, the upper layer (FFA) and lower (salt) are kept remain in the chemical glass, then the middle layer (glycerol) is filtered. In order to ensure that the salt is not screened along the process, then the screening use Filter Press Apparatus with 30 – 50 psi pressure. This method is different with the previous method [9] in which his method use Butchner funnel and separation funnel that separate glycerol and FFA from K3PO4 first, and then continued with the screening of glycerol from FFA.

The screening result of potassium phosphate salt is shown in Figure 9. This salt is able to be used as fertilizer. However, it still consists of glycerol which is easily melted so that crystallization process is required.

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Figure 9 Potassium Phosphate Salt as a Result of Glycerol Screening

The upper layer is a Free Fatty Acid (FFA) residue with pH of 5.0 (Figure 10) whereas the middle layer is glycerol with pH of 6. Glycerol solution as a result of screening process is shown in Figure 11 B. It can be seen from the figure that glycerol from screening process is clearer than crude glycerol.

Figure 10 FFA as a Result of Glycerol Screening

Figure 11 Crude Glycerol (A) and Purification Result (B)

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Figure 12 Diagram of Purification Process

2.3. Fluid TestingIn this study, the American Society of Testing and Material (ASTM) was used as standard practice in fluid testing. It is important to note whether the physio-chemical properties of glycerol by-product of palm oil biodiesel industry as potential base fluid is the primary focus in this study. According to previous studies by Amanullah (2005) [13], Rubiandini et al (2006) [14], and Setyawan et al (2011) [15], most vegetable oils were proven to be compatible with components and additives commonly used in diesel or mineral oil mud system. By comparison the result of several tests, it was performed to find the appropriate additive materials and the weaknesses of vegetable oil due to its undesired properties. The most undesired properties of vegetable oil are the relatively very high viscosity compared to minerals or diesel oil, as primary study [15].Since there are so many additives used in the making of OBM, where new more environmentally characteristics and low cost additives were continually developed to replace those which have detrimental impacts on the environment, further research should always be done to find suitable additives for vegetable oil use.

The testing is conducted to determine the physical and chemical properties of the fluids that were used before OBM formulation. The fluid parameters to be tested are:a. Specific gravity; shows the weight of the fluid.b. Kinematic viscosity; shows the reluctance of fluid that under the effect of gravity force to

flow.c. Flash point; shows the temperature of fluid begins to burn. Meanwhile, the fluid used

should have a high flash point value.d. Pour point; shows the lowest temperature of fluid that still able to flow. Meanwhile, the

fluid used should have a low pour point value.

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Physical properties of the fluids in this study will be compared with other synthetic oil and vegetable oils had been previously published. Biodiesel Palm Oil and Glycerol were used for the sample of synthetic oils. The comparison of these base oils are shown on the Table 3.

Table 3 Physical Properties of Base Fluids

Parameter Unit

Biodiesel

palm oil

(Rubiandini et al, 2007)

Biodie sel

Jatropha oil (Priwanza,

2007)

Saraline

(Setya wan et

al, 2011)

Sara par

(Setyawan et

al, 2011)

Crude castor

oil (Setya wan et

al, 2011)

Biodie sel

Palm Oil

Crude

Glyce rol

Glycerol

Purified

SG 0.87 0.85 0.78 0.76 0.95 0.9 1.09 1.24Pour Point °C 6.11 11 -16 -11 -21 5.9 4.4 -12

Boiling Point °C 80 120 N/A N/A N/A N/A N/A N/A

Flash Point °C 112.2 81 81 112.2 271.1 250 82 99

Kinematic visco

sitycSt 3.7 4.5 3.3 2.5 251.1 5 N/A N/A

2.4. Nuclear Magnetic Resonance Spectroscopy NMR that was used in this study is operated at frequency 500MHz (1H-NMR) and 125 MHz (13C-NMR). The results of NMR Spectrometry of several fluids are shown in Figure 13 and Figure 14.

Figure 13 NMR Spectrum of Crude Glycerol

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Figure 14 NMR Spectrum of Purified Glycerol

3. Results and Discussions

3.1. Specific Grafity The chart on Figure 15 shows the comparison of specific gravity with other base fluids. Specific gravity characteristics of the fluids were measured using the Picnometer according to API RP 13B procedure.

Figure 15 Specific Gravity of Glycerol Compared with Other Base Fluid

3.2.

Cloud Point and Pour PointThe chart on Figure 16 and Figure 17 show the comparison of cloud point and pour point with other base fluids. Cloud point and pour point characteristics of the fluids were measured using the Cloud Point and Pour Point Apparatus according to ASTM D 97 procedure.

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Figure 16 Cloud Point of Glycerol Compared with Other Base Fluid

Figure 17 Pour Point of Glycerol Compared with Other Base Fluid

3.3. Flash Point The chart on Figure 18 shows the comparison of flash point with other base fluids. Flash point characteristics of the fluids were measured using the Pensky-Martens Closed Cup Tester according to ASTM D 93 procedure.

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Figure 18 Flash Point of Glycerol Compared with Other Base Fluid

4. Conclusions1. The specific gravity minerals and biodiesel are lower than pure water due to kind of

oils. Specific gravity of glycerol is lower than glycerol purified due to impurities compound especially non-reacting methanol.

2. Biodiesel palm oil has higher flash point compared to glycerol, mineral, and other biodiesel, except crude castor oil (Setyawan, 2011). Hence, transportation and handling of biodiesel will have significantly lower fire hazard risk compared to glycerol, mineral, and other biodiesel.

3. Glycerol purified has excellent pour point characteristics compared to minerals and biodiesel, except saraline and crude castor oil (Setyawan, 2011), which are suitable for synthetic oil-based mud application in both tropical areas and cold weather. Glycerol purified also has advantages in terms of transportation, processing, storage, and material handling.

4. By adding phosphate acid to crude glycerol, the impurities are reduced and the crude glycerol became the glycerol purified. Hence, glycerol purified have characteristic such as higher flash point and lower cloud point and pour point compared to crude glycerol.

5. The characteristics and the properties of glycerol purified were found better than crude glycerol. Meanwhile, after purification, glycerol content is suitable for synthetic oil-based mud application.

5. References[1] Hambali, E., et al. 2007. Teknologi Bioenergi. Cet.1. Agromedia Pustaka, Jakarta.[2] Sahirman. 2009. “Analisis Finansial Dan Produksi Biodiesel.” Materi Diklat Level

Menengah. Departemen Pendidikan Nasional Dirjen Peningkatan Mutu Pendidik Dan Tenaga Pendidikan, Pusat Pengembangan Dan Peberdayaan Pendidik Dan Tenaga Pendidikan Pertanian. Cianjur.

[3] Pagliaro, M., Rossi, M. 2008. The Future of Glycerol: New Uses of a Versatile Raw Material. RSC Green Chemistry Book Series.

[4] Hambali, E. 2013. Materi Kuliah Teknologi Bioenergi. Sekolah Pascasarjana Institut Pertanian Bogor.

[5] Winarno, F. G. 1992. Kimia Pangan dan Gizi. PT. Gramedia Pustaka Utama, Jakarta.[6] SIDS Initial Assesment Report: Glycerol (CAS Number : 56-81-5). 2002. SIDS Initial

Assessment Meeting (SIAM), France.12

[7] Tovbin, LM, et al. 1976. Soap Manufacturing Second Edition.[8] Lotero, et al. 2005. “Synthesis of Biodiesel via Acid Catalysis”. Industrial & Engineering

Chemistry Research 44, 5353–5363.[9] Dasari. 2006. “Catalytic Conversion of Glycerol and Sugar Alcohols to Value Added

Product [Dissertation].” Missouri: University of Missouri.[10] Farobie, O. 2009. “Pemanfaatan Gliserol Hasil Samping Produksi Biodiesel Sebagai

Bahan Penolong Penghancur Semen [Thesis].” Bogor: Sekolah Pascasarjana Institut Pertanian Bogor.

[11] Kocsisová, T., et al. 2006. G-phase from Methyl Ester Production-Splitting and Refining. Petroleum & Coal 48(2): 1-5.

[12] El-Diwani, G., et al. 2009. “Development and Evaluation of Biodiesel Fuel and By-Products from Jatropha Oil.” Int J Environ Scien Technol 6(2): 219-224.

[13] Amanullah, Md. 2005. “Physio-chemical Characterization of Vegetable Oils and Preliminary Tests of Vegetable Oil-Based Muds.” SPE/IADC Middle East Drilling Technology Conference & Exhibition.

[14] Rubiandini, R., Cahyono, G., Sumirat, I., Susetyo, N., 2006, Penelitian Penggunaan Biodiesel Kelapa

[15] Setyawan, W., et al. 2011. “Alternative Use of Castor Oil for Vegetable Oil-Base Mud Environmentally Friendly Potential Domestic Oil-Base Mud.” Proceedings, Indonesian Petroleum Association Thirty-Fifth Annual Convention & Exhibition.

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