Biodiesel from Crude Rubber Seed Oil (CRSO)-Hevea brasiliensis sp. via non-catalytic Process Reaction I Wayan Susila a, Orchidea Rachmaniah a*, and M. Rachimoellah a a Department of Chemical Engineering Sepuluh Nopember Institute of Technology, Surabaya 60111 Indonesia * Corresponding Author s E-mail: orchideaceae@yahoo.com Keywords: Biodiesel; Buble column reactor; Hevea brasiliensis sp.; Non-catalytic methode; Rubber seed oil. Abstract In recent time, the world has been confronted with an energy crisis due to depletion fossil resources and increased environmental problems. Such situation has led to the increase of research for an alternative energy such as biofuels from sustainably biomass resources. Indonesia goverment via PERPRES No.1, 2005, about National Energy Strategy and via INPRES No.1, 2005, about Utilization and Supplying of Biofuels, support all the efforts which utilize the natural resources of Indonesia to overcome the energy crisis, and to find alternative energy. Among biofuels, biodiesel exhibits fuel properties which compatible to those of petroleum-based diesel, and is commercialized for use in existing motor vehicles. Vegetable oils are becoming a promising alternative to diesel fuel because they are renewable in nature and can be produced locally and environmental friendly as well. Indonesia which is abundant in natural resources could utilize their natural oil resources such as palm oil, jatropha curcas, corn stover, rambutan, papaya, rubber tree etc become raw material for biodiesel productions. Many researchers have already started their research in biodiesel production using crude rubber seed oil (CRSO) but neither their results were compromised with FBI requirements standard for biodiesel quality nor in Calculated Cetane Index (CCI) standard value. Because of those reasons, we conduct an experiments to overcome this prolems via non-catalytic methode. A supercritical methanol was used in this methode to produce high purity biodiesel in order to meet the requirements of FBI-standards. Transesterification reactions were conducted by using buble column reactor (BCR) under these conditions: 543-563 K, 140-160 molar ratio methanol to CRSO at atmospheric pressure reaction. In order to know the qualities of the biodiesel which is produced, the biodiesel was tested in different composition such as B-0, B-5, B-10, B-15, B-20 and B-100. Result showed by increasing temperature, the yield of biodiesel would increase. The best yield for biodiesel production, 77,54% were produced in 563 K and 160 molar ratio methanol to CRSO. The CCI Index also increased up to 47,5 compared to 46,23 which is produced by convensional methode (esterification and transesterification methode). Generally, biodiesel from CRSO via non-catalytic methode has good qualities regarding the FBI 2005 s standard requirements except the carbon micro residue. It was inferred that this biodiesel still has a high potential to produce scale when it is injected in diesel machine. Therefore, B-10 was recommended as the suitable composition when used as alternative fuels in diesel engine.
1. Introduction Biodiesel fuel (BDF) which is an alternative of the diesel derived from oils and fats, recently has been receiving an intensive attention, and in the currently used alkaline catalyst methode, triglycerides (TG) are trans-esterified in the presence of an alkaline catalyst either methanol and converted to fatty acid methyl esters (FAME). Although the alkaline catalyst methode has the benefit of using moderate reaction conditions, several aqueous washings are needed to remove the catalyst after the reaction. Moreover, the oils and fats used may contain water and free fatty acid react with the catalyst to produce saponified products, risking a reduction in the yield of FAME. Beside those problems, there are two others problems which are associated with this process. The first is due to the two-phase nature of vegetable oil/methanol (MeOH) mixture that requires vigorous stirring to proceed in the transesterification reaction. The second is products purification from residual catalyst which is left in the reaction product due to unreacted MeOH and saponified products. Transesterification reaction without catalyst utilization, which is proposed will solve those problems. The non-catalytic transesterification has several advantages. The removal of free fatty acids (FFAs) from oil by refining or preesterification is not required. In non-catalyric process, two types of reaction for ME formation will exist, namely TG transesterification and methyl esterification of fatty acids. Consequently, a higher yield can be obtained if compared to that produced by alkalinecatalyzed methode. In addition, because of free catalyst process, separation and purification become much simpler and environmentally friendly. The disadvantages of the non-catalytic process are the necessity of larger molar excess of MeOH (the required molar ratio of MeOH to oil was 24-42) and the higher operating temperature (513-623 K) than the catalytic one. Optimum temperature for the catalytic transesterification is 333 K while molar ratio of MeOH to oil is 60. This paper is aimed to study the MeOH molar ratio and reaction temperature of non-catalytic transesterification reaction of crude rubber seed oil (CRSO) from Hevea brasiliensis sp. on the biodiesel quality and study the CRSO-biodiesel on the diesel mechine performances. The effects of MeOH flow rate and reaction temperature on the conversion, yield of FAME and composition of the reaction product also investigated. 2. Experimental 2.1 Materials Rubber seed was obtained from PTPN XII East Java, Indonesia. Kernel were already separately from the seed and was drying under the sunshine for 90 minute in order to decrease their water content. Screw press was used to press the kernel in order to extract the crude rubber seed oil (CRSO) from the rubber kernel. 2.2 Reactor for non-catalytic transesterification Schematic flow diagram of reator used in the experiment is shown in Figure 1. The buble column reactor was a 500 ml four-necked flask equipped with a condensor, a pipe for methanol vapor feed and a temperature controller (TC). The reactor was placed in a mantle heater. The glass dehydration column was filled with the molecular sieves. A pump with a variable speed motor was used to control charging rate of MeOH. The tin bath was placed on an electric stove. Temperature of tin bath was monitored by a temperature indicator (TI). Temperatures of superheated methanol supplied to the reactor and liquid in the reactor were controlled with the TC. 2.3 Transesterification reaction procedure and conditions The reactor was initially charged with 200 ml of the CRSO and heated to the desired temperature. Reactions were conducted at 543, 548, 553, 558, and 563 K under atmospheric pressure. Liquid MeOH was pumped out of the dehyration column to the tin bath for vaporization. The MeOH vapor was taken through a ribbon heater and the reaction started by blowing the bubbles of superheated MeOH continuously into the reactor at fixed flow rate. Reacted products in gas phase were condensed and collected using a glass container. The reaction products were taken from the glass container every 60 minutes and then weighed (samples A). During the reaction course (360 minutes), 6 samples were collected.
VR SH Nomenclaturs: VR = vaporizer SH = super heater H = heater V = valve R = reactor Cd = condenser O = outlet Figure 1. Flow diagram of reactor used in non-catalytic transesterification experiment 2.4 Analysis Gas chromatography (GC) analyses of transesterified methylated products were performed on HP 5890 A series II gas chromatograph equipped with an on-column ejector, a flame-ionization detector (FID) and a DB-5HT (5%-phenyl)-methylpolysiloxane (6 m x 0,32 mm). The operating parameters were as follows: detector temperature, 370 o C; injector temperature, 365 o C; temperature program, 0 min at 80 o C, heat at a rate of 15 o C/min to 370 o C hold for 10 min. Carrier gas (H 2 )/Nitrogen (N 2 ) split ratio is 1:50 with pressure 60 Kpa [British Standard International, BSEN 14105:2003]. 2.5 Performance Test The biodiesel which resulted would be tested in stationer diesel machine using SAE J-1349, Desember 1980 test standard procedure. The parameters were tested: torsion, fuel consumption, ambient temperature, engine, oil, and exhaust ( o C), gas composition (CO, CO 2, dan O 2 ), power (BHP), effective average pressure, bmep (kpa), and specific fuel consumption, (sfc). All those parameters were measured in various blending composition such as B-0, B-5, B-10, B-15 and B-20. The stationer diesel machine has the following specifications: model Nissan DWE-47-50-HS-AV, 4 length of motor diesel, 4 cilinders, 83 cm x100 mm, stage volume: 2164 cc and power machine: 47 BHP/3200 RPM. 3. Results and Discussion Rubber seed as a raw material in this experiment was supplied by PTPN XII East Java Region and the Rubber seed kernal was already separated from their seed and was drying under the sunshine for 90 minutes in order to decrease their water content and to remove their film which cover the kernel surface [Bailey,1982]. Screw press was used to press the kernel, after their treatment, in order to extract the crude rubber seed oil (CRSO) from the rubber kernel and to get 31,08% for CRSO-yield. The physical properties of CRSO was performed in Table 1. The experiment results in different conditions, they were illustrated in Figure 2. The higher the temperature, the yield of biodiesel would be rised too, as well as the molar ratio increased. As the temperature was increased, the methanol (MeOH) would be in gas phase (superheat condition) and it is easier for methanol to react with CRSO in gas phase compared to another phase. The highest yield of biodiesel, 77,54%, was achived in 563K and 160 molar ratio MeOH to CRSO. The biodiesel also tested in different types of blending compositions (B-0, B-5, B-10, B-15, B-20 dan B-100) in order to known their performances in diesel machine (Table 2). The maximum power machine output was 36,948 PS in 2550 rpm. Those value was achived when the B-10 blending composition used, this composition also has specific fuel consumption (SFCe) at value 0,256 kg/ps.jam, and caloric value was 10738,2 kkal/kg. Those caloric value was
higher than solar s caloric value, 10500 kkal/kg (Tabel 3). Besides that, the combustion gas excess only given CO content 0,4 %-v for B-10 within low opacity value (the maximum value which allowed was 70%). Related to the engine test results B-10, it was already fullfilled the Environment Minister standard requirements No.5 year of 2006 and we could conclude that B-10 emission gas was environmental friendly. Based on the engine test results, B-10 was recommended as fuel for stationer diesel engine. B-10 presented 1,8% higher for power machine than when used solar as fuel. Those fuel also didn t cause detonation in machine test. Table 1. The physical properties of CRSO from different type of extraction process Parameter extraction treatment steaming without steaming Viscosity (cps) 50 45 Density (kg/l) 0,9209 0,9206 Water content (%) 0,20 0,17 FFA (%) 6,66 6,21 Boiling point ( o C) 170 175 Figure 2. Yield of biodiesel from CRSO by non-catalytic methode Table 2. Engine test result (2550 rpm) for biodiesel from CRSO by non-catalytic methode in various blending composition Blending composition LHV (kkal/kg) Density (g/ml) Ne (PS) SFCe (kg/ps.hour) m (%) CO (% v) CO 2 (% v) Opacity (%HSU) B-0 10500,0 0,835 36,26 0,256 41,24 2,0 8,0 - B-5 10642,1 0,846 36,95 0,256 41,79 1,6 4,4 59,6 B-10 10738,2 0,848 36,95 0,256 39,28 0,4 3,6 58,6 B-15 10858,3 0,852 34,20 0,259 37,92 0,8 4,4 60,2 B-20 10473,9 0,853 34,20 0,253 42,88 2,0 7,2 65,3 B-100 9184,4 0,882 Kinematic viscosity 5,19 cst
CRSO-biodiesel qualities was performed in Table 3 both for non-catalytic and conventional methode. Generally, non-catalytic biodiesel offered better qualities compared to the conventional biodiesel (via esterification and transesterification reaction) within the following: density, viscosity, CCI (calculated cetane index), and flash point. Non-catalytic biodiesel has better viscosity compared to the conventional biodiesel (5,086 cst). Those viscosity value indicated that CRSO s wax and gum could be removed via non-catalytic methode without disrupted the process reaction and interfere the biodiesel qualities. Wax and gum content were the major compound which indicated the viscosity of biodiesel in conventional methode. Biodiesel produced via non-catalytic methode has lower pour point (-6 o C), indeed, those level of pour point could be applied in countries which have four different seasons. As well as flash point, 200 o C, those high value represented easier to deposit and didn t blaze easily. Cu corrosion strip tested was resulted lower level (No.1b), those number indicated that CRSObiodiesel didn t get corrosion easily if it was stored in storage tank (generally made from Cu). Unfortunetaly, the micro carbon residue didn t meet the standard requirement either in sample or in 10% distillate residue (maximum value is 0,05 and 0,3%-mass respectively for micro carbon residue in 10% distillate residue and 10% distillate residue). However those problem could be overcome by blending the CRSO-biodiesel with solar in their use in order to decrease the scale which resulted in engine room. B-10 recommends blending composition to solve those problem based on the engine test results (Table 2). Table 3. Biodiesel from CRSO s qualities No Properties Unit Limitation Biodiesel-CRSO ASTM Noncataylitic Min Max Method conventional 1. Density 40 o C kg/m 3 850 890 D-1298 882 885,4 2. Kinematic Viscosity (40 o C) cst 2,3 6,0 D-445 5,19 5,086 3. Cetane number*) 51 - D-613 47,5* 46,23* 4. Pour Point o C - 18 D-97-6 ND 5. Flash Point o C 100 - D-93 200 99 6. Cu corrosion strip (3 hours at 50 o C) No. ASTM - No.3 D-130 N0.1b ND 7. micro carbon residue In sample - 0,05 0,126 ND % mass In 10% distillate - 0,3 D-4530 2,87 ND residue 8. Water and sediment % volume - 0,05 D-2709 D-1796 0 0,01 9. Distillation - 360 C temperature 90% D-1160 347 ND 10. Sulfated ash % mass - 0,02 D-874 0,01 ND 11. Sulphur ppm-m D-5453-100 (mg/kg) D-1266 0,72 0,052 12. Acid number mg-koh/g - 0,8 D-664 0,01 ND 13. Free Glyserol % mass - 0,02 D-6584 ND ND 14. Total Glyserol % mass - 0,24 D-6584 ND ND *analysis by ASTM D976-91 using Calculated Cetane Index CCI = 454,74 1641,416D + 774,74D 2 0,554B + 97,803(log B) 2 whereas D = density 15 o C (g/ml) via ASTM D-1298 or D-4052 and B = mid boiling temperature ( o C) 4. Conclusion Biodiesel qualities which was resulted from the experiment, generally, has better performance compared to the conventional ones. The experiment condition (563 K and 160 molar ratio MeOH to CRSO) gave the highest biodiesel yield (77,54%) and B-10 was the recommended blending composition for use in stationer diesel machine based on the engine test results. ND
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