The 5th AUN/SEED-Net Regional Conference on Biotechnology January 23rd-24th, 2013
Biodiesel Production from Methanol Transesterification of Jatropha curcas Oil with Sulfonated Polystyrene (S-PS) NIMPAN BANGUN 1 , FRISDA RIMBUN PANJAITAN 2 , ADELINA SIDABUTAR 3 1
University of Sumatera Utara, Chemical Department, Jl. Almamater Kampus USU, Medan, 20000, Indonesia 2 Indonesian Oil Palm Research Institute, Product Development and Quality, Jl Brigjend Katamso 51, Medan, 20000, Indonesia 3 University of Sumatera Utara, Chemical Department, Jl. Almamater Kampus USU, Medan, 20000, Indonesia E-mail:
[email protected] E-mail:
[email protected]
Abstract : This paper investigates the production of biodiesel (fatty acid methyl esters) by the acid transesterification reaction from non-food oil with high free fatty acid (7% of FFA), Jatropha curcas oil using S-PS catalyst. Single step methanol-acid transesterification were carried out in a high pressure reactor and reactions were studied at 4 wt% and 8 wt% S-PS catalyst at a temperature of 80 and 120o C with various molar ratios of methanol-to-oils. The S-PS was developed in homogenous sulfonation and the degree of sulfonation is 6.2%. It is interesting to find that single step methanolacid transesterification yielded 93.35 wt% methyl esters at a reaction temperature of 120o C, S-PS 8 wt% and reaction time 6 hours. It was indicated that the S-PS catalyst reduced conventional synthesis routes, two step esterification-transesterification, for producing biodiesel from high free fatty acid oil. Keywords: methanol-acid transesterification, S-PS catalyst, Jatropha curcas oil, FFA, sulfonation Introduction: Diversity of sources of raw materials for biofuel energy it is necessary to develop. Inedible oils such as Jatropha curcas oil is attractive and provides a great opportunity processed into biodiesel fuel [1]. In a variety of factors, the availability of Jatropha oil can contain high FFA (over 1%). To process the oils with high free fatty acids into biodiesel becomes a challenge, because the usual catalyst technology using ineffective, its leads to the formation of soap. Technology with H2 SO4 catalyst has been performed, but caused many operational problems such as the reaction is very slow, unstable yield methyl ester because of easily hydrolyzed. Production of esters via transesterification using acid catalyst development is still very limited due to the nature of the acid catalyst could not mix with oil. The methyl ester and the reaction rate was very low. The S-PS is an acid catalyst in the form of polymers. The using of this catalyst is to accelerate the mixing of oil with methanol more effectively also can used as a transesterification catalyst. The S-PS catalyst separation is easier than H2 SO4 because of the larger molecular weight. The purpose of the present paper is to investigate the preparation of esters from Jatropha oilshigh FFA with S-PS catalyst . The use of an acid catalyst S-PS anticipated to be used for raw material ester from Jatropha oils-high FFA 7% without passing through the stage of the esterification reaction. Materials and Methods: The Jatropha oils-high FFA 7% and 0,45% water content was supplied by estate private company, Medan. The other chemicals (analytical grade) were purcahased from Merck. Preparation of catalyst, S-PS was prepared by the homogenous sulfonation. Sulfonated polystyrene (S-PS) obtained precipitated with methanol. The precipitate was then filtered, washed with methanol repeatedly until the filtrate pH 7. The solid was dried under vacuum. Retrieved yield 84.9% and 6.2% sulfonate degree, glass transition temperature of 178o C. The FT-IR technique has also been applied in the characterization of catalyst S-PS. FT-IR spectra of catalysts SPS were obtained with a Bruker Alpha-T, catalysts were measured as KBR pellets. The sulfonation
The 5th AUN/SEED-Net Regional Conference on Biotechnology January 23rd-24th, 2013 level was determined by titration with NaOH solution in methanol. Transesterification of Jatropha oils-high FFA by catalyst S-PS, Jatropha oils-high FFA reacted with methanol in the presence of 4 wt% and 8 wt% S-PS catalyst at a temperature of 80 and 120o C with various molar ratios of methanol-to-oils. Reaction was conducted in high pressure reactor PARR 4848 series. Product analysis, esters was quantified using gas chromatography 14B (Shimadzu). A DB-5HT column (15m×0.32mm×0.1 μm) was used for the analytical work. The oven temperature was held at 50o C for 1min, increased to 180o C at a rate of 15o C/min and increased to 230o C at a rate of 7o C/min and again increased to 380o C at a rate of 10o C/min, and then held at the temperature for 10 min. 1,2,4butanetriol and 1,2,3-tricaproylglycerol were used as the internal standards. Results and Discussion : FT-IR measurements The FT-IR spectra of catalyst S-PS powders were taken over the range of wavenumbers from 450 to 4000 cm-1 (Figure 1). The SO3 - group antisymmetric peaks can be assigned to the peaks at 1329,67 and 1274,51 cm-1 and symmetric vibrational adsorption peaks can be assigned to the peaks at 1089 and 1049,50 cm-1 , respectively. Sulfonic group vibration bands are reported at approximately 1040
Figure 1. FT-IR spectra of catalyst S-PS and 1180 cm-1 . Yang et al [1] have studied the analysis of sulfonic groups, spectra are shown over the range from 800 and 1400 cm-1 . Our result are in agreement with [2][3], we verified that the S-O vibration at 880,63 cm-1 . Transesterification of Jatropha oils-high FFA by catalyst S-PS In the case of transesterification of vegetable oil with methanol, acid catalysis is unfavorable [4], mostly sulfuric acid because it mainly distributes into the MeOH phase and yet it must activate the carbonyl oxygen of triglyceride in vegetable oil to enable the reaction. Because of the S-PS is an acid catalyst in the form of polymers, organic acid catalysts, the using of this catalyst is to accelerate the mixing of oil with methanol more effectively also can used as a transesterification catalyst. Starting conditions for this experiment were follow as: amount catalyst, 4 and 8 wt% (oil mass basis), reaction
The 5th AUN/SEED-Net Regional Conference on Biotechnology January 23rd-24th, 2013 temperature 80 and 120o C, molar ratio of oil: methanol= 1:12, and reaction time, 6 h. Sulfuric acid also was used as a comperative catalyst in this acid-transesterification. The highest biodiesel yield was 100
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Figure 2. Biodiesel production using catalyst S-PS under various conditions using catalyst S-PS, 8 wt% (Figure 2). The yield then increased with increasing the temperature and amount of catalyst. When H2 SO4 was used as catalyst with increasing the temperature and amount of catalyst, the biodiesel yields were 8,87 and 9,7 wt%. These result are in agreement with [4]. In particular, the S-PS catalyst showed the highest reactivity and the biodiesel yield reached 93,35 wt%. 80
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Figure 3. Glycerides composition using catalyst S-PS after reaction under various conditions
The 5th AUN/SEED-Net Regional Conference on Biotechnology January 23rd-24th, 2013 The reaction of transesterification using the sulfuric acid catalyst showed the lowest activity (Figure 3) and the biodiesel yield was only 8,87% (Figure 2), even after increasing the amount of catalyst 8 wt%. Furukawa et al reported that the reason for this is that the dissociated proton from the catalyst was less able to attack the carbonyl oxygen in TG because sulfuric acid was relatively difficult to solubilize in the oil phase and much of the sulfuric acid was distributed to the methanol phase. With using of catalyst S-PS, organic acid catalysts, the reactivity increased because the distribution rate of protons in the oil phase was increased. The presence of high-FFA and water in Jatropha oil was not affected the transesterification. The experimental results shows catalysts S-PS had an excellent catalytic activity and stability. There is no soaps formed. This makes the amount of available catalyst for the transesterification reaction to be reduced and also complicates the down streaming separation and the biodiesel purification.The catalyst also shown water-tolerance that could show promising for low quality feedstocks in terms biodiesel production. Conclusions: The experimental results show S-PS catalyst had an excellent catalytic activity and stability in the acid-methanol transesterification of jatropha oil to biodiesel, and the optimum conditions are: 12:1 molar ratio of methanol to oil, addition of 8wt% catalyst, 120°C and about 6 h of reaction time. Therefore, it has a tremendous potential to provide a friendly low cost method in biodiesel production from low quality raw feed stocks with high FFA and high water content.
References: [1] H.A. Abdelgadir, M.G. Kulkarni, M.P. Arruda, J. Van Staden. 2012. Enhancing seedling growth of Jatropha curcas – A potential oil seed crop for biodiesel. South African Journal of Botany. 78: 8895 [2] J.C. Yang, M.J. Jablonsky, J.W. Mays. 2002. NMR and FT-IR studies of sulfonated styrene-based homopolymers and copolymers. Polymer. 43: 5125-5132 [3] C.R. Martins, G. Ruggeri, M-A. De Paoli. 2003. Shynthesis in pilot plant and physical properties of sulfonated polystyrene. J.Braz. Chem.Soc. 14(5): 797-802 [4] S. Furukawa, Y. Uehara, H. Yamasaki. 2010. Variables affecting the reactivity of acid-catalyzed transesterification of vegetable oil with methanol. Bioresource Technology. 101: 3325-3332 [5] K.H. Kay and S. Md Yasir. 2012. Biodiesel production from low quality crude jatropha oil using heterogenous catalyst. APCBEE Procedia. 3:23-27
