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Synthesis of glycerol-free biodiesel with DMC over sulfonated imidazolium ionic liquid Pei Fan, Jiayan Wang, Shiyou Xing, Lingmei Yang, Gaixiu Yang, Junying Fu, Changlin Miao, and Pengmei Lv Energy Fuels, Just Accepted Manuscript • DOI: 10.1021/acs.energyfuels.7b00115 • Publication Date (Web): 08 Mar 2017 Downloaded from http://pubs.acs.org on March 12, 2017
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Synthesis of glycerol-free biodiesel with DMC over sulfonated
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imidazolium ionic liquid
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Pei Fana,b,c,d, Jiayan Wanga,f，Shiyou Xinga,b,c,d, Lingmei Yanga,b,d, Gaixiu Yanga,b,d, Junying Fua,b,d, Changlin Miaoa,b,d1, Pengmei Lva,b,d,e2 a Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou 510 640, China. b Key Laboratory of Renewable Energy, Chinese Academy of Sciences, Guangzhou 510640, China. c University of Chinese Academy of Sciences, Beijing 100049, China. d Guangdong Key Laboratory of New and Renewable Energy Research and Development, Guangzhou 510640, China. e Collaborative Innovation Center of Biomass Energy, Henan Province, Zhengzhou 450002, China. f Nano Science and Technology Institute, University of Science & Technology of China,Suzh ou 215123, China
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Abstract: Ionic liquid is green solvent and catalyst. A new approach of using dimethyl carbonate (DMC) catalyzed by sulfonated imidazolium ionic liquid (SIIL) producing glycerol-free biodiesel was developed. Together the fatty acid methyl ester (FAME), the other two products fatty acid 1,3-dimethoxypropyl ester and 1,3-dimethoxypropan-2-ol were also generated which could be used as oxygenate additive without separation from biodiesel. The overall reaction pathway was resolved upon the products analysis, which could well explain the whole process and products distributions. In this paper the effects of the molar ratio of DMC to rapeseed oil, catalyst dosage, reaction temperature, and reaction time were explored. The highest yield of fatty acid methyl ester (FAME) with the SIIL catalyst 1-propylsulfonate-3-methyl imidazolium hydrogen sulfate ([PrSO3HMIM][HSO4]) reached 95.77% under optimum conditions.
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1. Introduction Biodiesel (BD), derived from vegetable oils and animal fats, is a form of clean renewable energy and is considered an excellent substitute for diesel fuel. The main advantages of biodiesel include renewability, high biodegradability, low pollutant emissions, high flashpoint, and excellent lubricity. In its most common formulation, biodiesel is chemically synthesized by reacting oils, such as rapeseed oil, soybean oil, etc. with
Key words: ionic liquid DMC biodiesel transesterification
1
Corresponding author. Tel.: +86 20 87057760; Fax. +86 20 87065195. E-mail address:
[email protected] 2 Corresponding author. Tel.: +86 20 87057760; Fax. +86 20 87065195. E-mail address:
[email protected] (P. M. Lv)
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short-chain alcohols, such as methanol and ethanol during the transesterification process or the esterification of fatty acids 1 catalyzed either by acids, bases 2-4 or enzymes 5, 6. The traditional transesterification process generates glycerin as byproduct, which accounts for 10% of the feedstock. Thus, several purification steps are required to separate the FAME from glycerin for its further utilization. The most popular purification method to remove the residual catalyst and glycerin is a water washing process. However, this process has its drawbacks: the large volume of water required, as more as three times the amount of biodiesel used, and the need to treat the wash water before releasing it back into the environment. In summary, the economic feasibility of the traditional methanol-biodiesel production is limited due to the quality of the glycerin produced, and the cost involved in the purification process. To overcome the formation of glycerin, researchers have started to produce glycerol-free biodiesel by using dimethyl carbonate (DMC) as an alternate methylating agent to methanol. DMC is a well-known, non-toxic reagent and green solvent that has been used in many applications, especially for carboxymethylation and methylation reactions 7, 8. The reaction with DMC can solve the problem in products separation and purification as no glycerol is produced in the reaction. The substitution of methanol with DMC has a major impact on the overall cost of the production process. Examples of biodiesel preparation using DMC and base or enzyme catalysts have recently started to emerge. DMC has better compatibility with oils, thus forming homogeneous reaction systems, which overcomes the problem of mass transfer. For example, Ilham 9-11 showed that triglycerides could be converted into FAME by reacting it with DMC in a non-catalytic supercritical process at 300 °C/20 MPa for 20 min with a 42:1 molar ratio of DMC to oil; a satisfactory 97.4% yield of FAME was obtained. Unfortunately, this high-temperature and -pressure reaction system is not suitable for industrialization. In another study, the transesterification was carried out by the catalysis of immobilized-lipase or lipase in a solvent-free system and FAME was obtained in yields higher than 90% under optimized conditions 12-14. There are other examples of transesterification using DMC, catalyzed by a variety of solid bases including metal oxides 15, 16, zeolites 17, and soluble base KOH 18-20. Kinetic studies of these transesterification reactions have also been reported 19, 21. Recently, ionic liquids (ILs) have attracted much interest in biodiesel production. ILs have a wide liquid range, high catalytic activity and thermal stability, numerous design possibilities, tunable physical properties, etc. They have been studied as solvents for the enzymatic methanolysis of triglycerides 22, as hydrophobic additives for the immobilization of enzymes 23, as Brønsted acidic and alkaline catalysts 24-31, or as composites mixed with heteropolyacids 32 to form new catalytic systems in the preparation of biodiesel. In our study, we first used a Brønsted imidazolium ionic liquid as catalyst in the transesterification reaction. And different reaction conditions were investigated to determine their influence on the yield of FAMEs, including reaction temperature, reaction time, molar ratio of substrates, and catalyst dosage. All of the experiments were replicated for 3 times at least to ensure the accuracy. The products were determined by GC-MS and the yield of FAME was analyzed by GC with internal standard method. The proposed mechanism of the acid-catalyzed DMC-BD transesterification process is discussed in this paper.
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2. Experiments details 2.1 Experiments The IL [PrSO3HMIM][HSO4] was purchased from the Shanghai Cheng Jie chemical Co. LTD. All chemicals were used as received without any pre-treatment. The reactions were performed in a thick-walled pressure vessel equipped with a magnetic stirrer immersed in an oil bath. The reactions were conducted at sufficiently high agitation speed to overcome mass transfer limitations during biodiesel production. The operating parameters designated for the IL-catalyzed process included a temperature range of 80–130 °C, six levels of catalyst concentrations between 5 and 30 wt.% (relative to the weight of rapeseed oil), molar ratios of DMC to rapeseed oil between 2:1 and 10:1, and reaction times in the range of 3–8 h. Single factor optimization (tune up one variable at a time) is used in this paper. After the reaction mixture was cooled to room temperature, the upper layer was separated by decantation, and then distilled under vacuum to remove excess DMC. The yield of FAME was determined by gas chromatography and the products analyzed by GC–MS. 2.2 Analysis of products The FAME was analyzed using a Shimadzu Gas Chromatograph (GC-2010) equipped with the AOC-20i automatic injection port and a flame ionization detector (FID). The capillary column was a DB-WAX (30 m × 0.25 mm × 0.25 µm); methyl heptadecanoate was used as the internal standard. A GC-MS spectrometer (GC-MS, Agilent 7890A-5975C) equipped with an Agilent HP-5 column (30 m × 0.25 mm × 0.25 mm) was used. The analytes were dissolved in acetone and separated using the following temperature program: from 50 °C (held for 2 min) to 300 °C at 10 °C min-1, then held at 300 °C for 10 min. The major chemical constituents were identified using the NIST 2014 Mass Spectral Library. The FID response was linear for each component over the concentration ranges used, and the content analyses of the products generated are summarized in terms of percentage of peak area. 3. Results and discussion 3.1 Analysis of products The GC-MS spectra in Fig.1 shows that the main products in rapeseed-biodiesel are methyl linoleate (2) and methyl oleate (3), followed by the methyl palmitate (1) which is consistent with the results of the gas chromatography. Specially, the fatty acid 2,3-dimethoxypropyl ester such as 2,3-dimethoxypropyl palmitate (7) and 2,3-dimethoxypropyl oleate (9) were detected at 24.51 and 25.90 min for upper layer analysis and 2,3-dimethoxypropan-1-ol (10)、1,3-dimethoxypropan-2-ol (11) were detected for the lower layer analysis. And this founding has never been reported relating to DMC-BD before. Excluding the common gaseous products of methanol and CO2, the liquid products of acid IL-catalyzed transesterification of DMC are significantly different with solid-base-catalyzed reactions 19, 21, 33, in which the products are fatty acid glycerol carbonates (FAGCs) and glycerol dicarbonate (GDC). In addition, glycerol carbonate is generated in solid-base-catalyzed reactions. This distinct difference is possibly caused by
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the different catalytic mechanisms and reaction pathways of two systems, as shown in Fig.2 and Fig. 3, respectively. Ether and ester functional groups are commonly used as oxygenate additives 34 in biofuels and are introduced to increase the oxygen content, which may further reduce the engine exhaust emissions and improve the low-temperature flow properties. For example, dimethyl ether has been added to fuels to significantly reduce smoke and has been found to improve combustion quality 35, 36. It can be inferred that fatty acid 1,3-dimethoxypropyl can also act as oxygenate additives, due to the presence of the same functional groups; therefore, additional separation and purification processes may not be required.
O
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Fig. 1. GC-MS analysis of products. A. Upper layer: 1. Methyl palmitate, 2. Methyl linoleate, 3. Methyl oleate, 4. Methyl linolenate, 5. Methyl stearate, 6. Methyl cis-13-docosenoate, 7. 2,3-Dimethoxypropyl palmitate, 8. Methyl behenate, 9. 2,3-Dimethoxypropyl oleate; B. Lower layer: 10. 2,3-dimethoxypropan-1-ol 11. 1,3-dimethoxypropan-2-ol.
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Fig.2 Solid base catalyzed transesterification of DMC with TG19, 21, 33
3.2 Mechanism of acid-catalyzed DMC-BD transesterification We proposed a mechanism for this catalytic process analogous to the mechanism of the acid-catalyzed MeOH-BD transesterification reaction 37, 38 and the DMC methylation reaction 7, 39, 40. Thus, H+ from the IL catalyst attacks the triglyceride (TG); the protonated triglyceride then reacts with DMC to form an intermediate, which decomposes to FAME and the active moieties a and b. The possible pathways are as follows. First, a reacts with b to form intermediate c, which decomposes to give CO2 41 and the fatty acid 1,3-dimethoxypropyl ester, d. Second, DMC acts as a methoxycarbonylating agent. The nucleophile a attacks the carbonyl functionality of DMC 39, 42 by a BAC2 mechanism, giving intermediate c, which loses CO2 to produce d following the AAL2 mechanism 43 and the methoxide anion which reacts with H+ to form methanol and finally, at the 4th step, methanol reacts with fatty acid 1,3-dimethoxypropyl ester d to produce 1,3-dimethoxypropan-2-ol. This latter step could be explained by the mechanism of the acid-catalyzed MeOH-BD transesterification reaction. The reactions in the first and second steps are competitive reactions; the reactions of a with DMC and b occur simultaneously. However, the reaction between a and b is probably the dominant one. Based on the principle of hard and soft acids and bases (HSAB) 44, 45, the triglyceride, which is more electronegative than a, coordinates preferentially to H+ and avoids the production of glycerol that would be formed if a coordinated to H+.
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Fig. 3. Proposed mechanism for the acid-catalyzed transesterification of DMC with TG.
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3.3 Effects on yield of FAME 3.3.1 Molar ratio of DMC to rapeseed oil The molar ratios were varied from 2 to 10 in six different experiments, while keeping the other parameters constant. As shown in Fig. 4.A, the yield of FAME steeply increased when the ratio was increased from 2:1 to 5:1. This is due to the excess DMC shifting the reaction equilibrium towards the formation of products. On the other hand, the yield of FAME decreased when the molar ratio increased from 5 to 6. We speculate that more methoxide anion is formed as a result of the excess DMC, which consumes more H+ and
O
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decreases the rate of the protonation of triglyceride, thus decreasing the overall conversion rate. When the molar ratio increased from 6 to 10, the yield of FAME was almost constant due to the state of equilibrium. The optimum molar ratio of DMC to rapeseed oil was 5:1 and is consistent with the enzyme- and solid-base-catalyzed transesterification reactions 14, 18 . As DMC can be used as an oxygenated additive, which presents good blend fuel properties to improve combustion and reduce emissions of diesel engines46, there is no need to separate excess DMC from the generated biodiesel in industrial applications.
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3.3.2 Reaction time Fig 4.B shows the variation of yield with time. A gentle increase in yield of FAME was observed as the reaction time increased. After 3 h, the yield of FAME was over 70%. And the yield increased to 95.77% as the time extended to 5h. It might be that the reaction system obtained the enough activation energy and the catalyst was fully contacted with the reaction substrate. But when the reaction time was increased from 5 h to 8 h, the yield barely changed. It could be explained that the reaction reached the chemical equilibrium thus the yield did not increase more. Hence, 5 h was chosen as the optimal reaction time considering energy efficiency in industrial production. 3.3.3 Reaction temperature The effect of temperature on the yield of FAME is depicted in Fig 4.C. The reaction temperature was varied from 80°C to 130°C in six experiments while the other parameters were kept constant. The yield of FAME increased sharply as the temperature was raised from 80°C to 100°C. It could be assumed that the viscosity of IL decreased with increasing temperature, thus improving the rate of mass transfer in the heterogeneous reaction system. Moreover, higher temperature allows the system to exceed the activation energy required for the reaction, leading to increased conversion rate. We conclude that reaction temperature is one of the major factors affecting the yield of FAME in the transesterification with DMC; a similar conclusion was also reported by Ilham 9-11 in a non-catalytic supercritical process at high temperature and high pressure. When temperature increase from 100°C to 120°C, the yield of FAME added not obviously and then decreased to 91.44% at 130°C. We assumed that the concentration of DMC in reaction system might have decreased due to its evaporation (b.p. 90 °C) at 130°C lead to decrease the conversion. The highest yield 95.77% was obtained at 110°C so that we choose 110°C as the optimum temperature. 3.3.4 Catalyst dosage In general, the amount of catalyst has a significant effect on the catalytic performance. Therefore, the effect of catalyst dosage on the transesterification efficiency was investigated in detail. As shown in Fig 3.D, the yield increased sharply from 19% to 78% when catalyst dosage increased from 5% to 15% and then grew mildly when increasing the catalyst loading from 15% to 25%. It is obvious that increasing the catalyst dosage could improve the yield of FAME; however, the yield decreased to 90% when catalyst increased to 30%. It is explained that the concentration of substrates decreases and IL viscosity increases when too much catalyst is used , which causes the reduction of yield.
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Fig 4. Effects on yield of FAME. A. Molar ratio of DMC to rapeseed oil. Reaction conditions: 110 °C, 25 wt%, 5 h; B. Reaction time. Reaction conditions: 110 °C, 25 wt%, 5:1; C. Reaction temperature. Reaction conditions: 25 wt%, 5 h, 5:1; D. Catalyst dosage: 110 ºC, 5:1, 5 h.
4. Conclusion 1-Propylsulfonate-3-methyl imidazolium hydrogen sulfate ([PrSO3HMIM][HSO4]) was evaluated in the glycerol-free synthesis of biodiesel from DMC and rapeseed oil. The yield of FAME could reach a maximum of 95.77% at 110 ºC after 5 h with a molar ratio of DMC and oil 5:1 and 25 wt.% catalyst. The generated fatty acid 1,3-dimethoxypropyl ester could be used as fuel in biodiesel and the products avoided additional separation and purification processes. The reaction mechanism was proposed. This work showed that Brønsted-acid ILs have great potential in DMC transesterification for preparing glycerol-free biodiesel. Acknowledgement This work was supported by the National Natural Science Foundation of China (21576260, 21506217), the Natural Science Foundation of Guangdong Province (No. 2016A030308004 and No. 2015A030313720) and the Special Funds of Applied Science and Technology Research of Guangdong Province (No. 2015B020241002). Reference
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[1] M.J. Ramos, C.M. Fernandez, A. Casas, L. Rodriguez, A. Perez, Influence of fatty acid composition of raw materials on biodiesel properties, Bioresource technology, 100 (2009) 261-268. [2] K. Wilson, A.F. Lee, Rational design of heterogeneous catalysts for biodiesel synthesis, Catalysis Science & Technology, 2 (2012) 884-897. [3] M.G. De Paola, E. Ricca, V. Calabro, S. Curcio, G. Iorio, Factor analysis of transesterification reaction of waste oil for biodiesel production, Bioresource technology, 100 (2009) 5126-5131. [4] D.E. López, J.G. Goodwin, D.A. Bruce, E. Lotero, Transesterification of triacetin with methanol on solid acid and base catalysts, Applied Catalysis A: General, 295 (2005) 97-105. [5] S.H. Ha, M.N. Lan, S.H. Lee, S.M. Hwang, Y.-M. Koo, Lipase-catalyzed biodiesel production from soybean oil in ionic liquids, Enzyme and microbial technology, 41 (2007) 480-483. [6] N.I. Ruzich, A.S. Bassi, INVESTIGATION OF ENZYMATIC BIODIESEL PRODUCTION USING IONIC LIQUID AS A CO-SOLVENT, Canadian Journal of Chemical Engineering, 88 (2010) 277-282. [7] M. Selva, E. Militello, M. Fabris, The methylation of benzyl-type alcohols with dimethyl carbonate in the presence of Y- and X-faujasites: selective synthesis of methyl ethers, Green Chem., 10 (2008) 73-79. [8] A. E, Reaction of the Ambident Electrophile Dimethyl, JOC NOTES, (2007). [9] Z. Ilham, S. Saka, Dimethyl carbonate as potential reactant in non-catalytic biodiesel production by supercritical method, Bioresource technology, 100 (2009) 1793-1796. [10] Z. Ilham, S. Saka, Two-step supercritical dimethyl carbonate method for biodiesel production from Jatropha curcas oil, Bioresource technology, 101 (2010) 2735-2740. [11] Z. Ilham, S. Saka, Optimization of supercritical dimethyl carbonate method for biodiesel production, Fuel, 97 (2012) 670-677. [12] L. Zhang, S. Sun, Z. Xin, B. Sheng, Q. Liu, Synthesis and component confirmation of biodiesel from palm oil and dimethyl carbonate catalyzed by immobilized-lipase in solvent-free system, Fuel, 89 (2010) 3960-3965. [13] T. Xue, synthesis of biodiesel from cottonseed oil and dimethyl carbonate catalysted
by immobilized
lipase, Petrochemical Technology, (2009). [14] E.-Z. Su, M.-J. Zhang, J.-G. Zhang, J.-F. Gao, D.-Z. Wei, Lipase-catalyzed irreversible transesterification of vegetable oils for fatty acid methyl esters production with dimethyl carbonate as the acyl acceptor, Biochemical Engineering Journal, 36 (2007) 167-173. [15] Y. Tang, Q. Cheng, H. CaO, L. Zhang, J. Zhang, H. Li, Coupling transesterifications for no-glycerol biodiesel production catalyzed by calcium oxide, Comptes Rendus Chimie, 18 (2015) 1328-1334. [16] Y. Syamsuddin, M.N. Murat, B.H. Hameed, Transesterification of Jatropha oil with dimethyl carbonate to produce fatty acid methyl ester over reusable Ca–La–Al mixed-oxide catalyst, Energy Conversion and Management, 106 (2015) 1356-1361. [17] S. xiao-wei, Esterification of Salicylic Acid with Dimethyl Carbonate over Mesoporous Aluminoslicate, Industrial & Engineering Chemistry Research, (2009). [18] B.M. Panchal, S.B. Dhoot, S.A. Deshmukh, M.R. Sharma, M.S. Kachole, Production of DMC-BioD from Pongamia pinnata seed oil using dimethyl carbonate, Fuel, 109 (2013) 201-205. [19] L. Zhang, B. Sheng, Z. Xin, Q. Liu, S. Sun, Kinetics of transesterification of palm oil and dimethyl carbonate for biodiesel production at the catalysis of heterogeneous base catalyst, Bioresource technology, 101 (2010) 8144-8150. [20] F.A. Dawodu, O.O. Ayodele, J. Xin, S. Zhang, Dimethyl carbonate mediated production of biodiesel at different reaction temperatures, Renewable Energy, 68 (2014) 581-587. [21] M.R. Islam, Y.M. Kurle, J.L. Gossage, T.J. Benson, Kinetics of Triazabicyclodecene-Catalyzed Canola Oil
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Conversion to Glycerol-free Biofuel Using Dimethyl Carbonate, Energy & Fuels, 27 (2013) 1564-1569. [22] H. Zhao, Z. Song, O. Olubajo, J.V. Cowins, New Ether-Functionalized Ionic Liquids for Lipase-Catalyzed Synthesis of Biodiesel, Applied Biochemistry and Biotechnology, 162 (2010) 13-23. [23] R.Y. Cabrera-Padilla, M.C. Lisboa, M.M. Pereira, R.T. Figueiredo, E. Franceschi, A.T. Fricks, A.S. Lima, D.P. Silva, C.M. Soares, Immobilization of Candida rugosa lipase onto an eco-friendly support in the presence of ionic liquid, Bioprocess and biosystems engineering, 38 (2015) 805-814. [24] M. Han, W. Yi, Q. Wu, Y. Liu, Y. Hong, D. Wang, Preparation of biodiesel from waste oils catalyzed by a Bronsted acidic ionic liquid, Bioresource technology, 100 (2009) 2308-2310. [25] Z. Tong-mei, Synthesis
of biodiesel through catalyzed by a novel transesterification alkaline ionic liquid,
journal of Fuel Chemistry and Technology, 42 (2014) 200-206. [26] L. Jinhua, Preparation of biodiesel by transesterification from cottonseed oil using the basic dication ionic liquid as catalysts Journal of Fuel Chemistry and Technology, 38 (2010) 275-280. [27] A. Zhang, synthesis of biodiesel using new basic ionic liquid as catalyst, Applied Chemical Industry, 38 (2009) 167-177. [28] M. Fan, Preparation of biodiesel from soybean
oil catalyzed by imidazolide basic ionic liquids, New
chemical materials, 40 (2012) 115-117. [29] Y.A. Elsheikh, Z. Man, M.A. Bustam, S. Yusup, C.D. Wilfred, Bronsted imidazolium ionic liquids: Synthesis and comparison of their catalytic activities as pre-catalyst for biodiesel production through two stage process, Energy Conversion and Management, 52 (2011) 804-809. [30] Y.A. Elsheikh, Z. Man, A. Bustam, S. Yusup, F.H. Akhtar, I.K. Mohamed, Evaluation of catalytic activity of two functionalized imidazolium ionic liquids for biodiesel fuel production by a two-stage process, Journal of Chemical Technology & Biotechnology, 89 (2014) 998-1006. [31] Y.A. Elsheikh, Preparation of Citrullus colocynthis biodiesel via dual-step catalyzed process using functionalized imidazolium and pyrazolium ionic liquids for esterification step, Industrial Crops and Products, 49 (2013) 822-829. [32] J. Wu, Y. Gao, W. Zhang, Y. Tan, A. Tang, Y. Men, B. Tang, Esterification of cooking oil for biodiesel production using composites Cs2.5H0.5PW12O40/ionic liquids catalysts, Applied Petrochemical Research, 4 (2014) 305-312. [33] D. Fabbri, V. Bevoni, M. Notari, F. Rivetti, Properties of a potential biofuel obtained from soybean oil by transmethylation with dimethyl carbonate, Fuel, 86 (2007) 690-697. [34] N. Rahmat, A.Z. Abdullah, A.R. Mohamed, Recent progress on innovative and potential technologies for glycerol transformation into fuel additives: A critical review, Renewable and Sustainable Energy Reviews, 14 (2010) 987-1000. [35] T. A.Semelsberger, Dimethyl ether (DME) as an alternative fuel, Journal of power sources, 156 (2006) 497-511. [36] A.M.Namasivayam, Biodiesel, emulsified biodiesel and dimethyl ether as pilot fuels for natural gas fuelled engines, Applied Energy, 87 (2010) 769-778. [37] H.Q. Zhang Pingbo, Theorectical study on the favorable active site and the mechanism of acid-catalyzed transesterification reaction of biodiesel production, Computers and Applied chemistry, (2014). [38] A.C.H. da Silva, E.L. Dall’Oglio, P.T. de Sousa Jr, S.C. da Silva, C.A. Kuhnen, DFT study of the acid-catalyzed ethanolysis of butyric acid monoglyceride: Solvent effects, Fuel, 119 (2014) 1-5. [39] P.T.A.M. SELVA, The chemistry of dimethyl carbonate, Accounts of chemical research, (2002) 10. [40] S.Memoli, Dimethylcarboate for ecofriendly methylationreactions, Chemosphere, 43 (2001) 115-121.
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[41] P.A. Glaude, W.J. Pitz, M.J. Thomson, Chemical kinetic modeling of dimethyl carbonate in an opposed-flow diffusion flame, Proceedings of the Combustion Institute, 30 (2005) 1111-1118. [42] P. TUNDO, DIMETHYL CARBONATE: GREEN SOLVENT AND AMBIDENT REAGENT, Reference to a chapter in an edited book: Green Chemical Reactions, (2006) 213-232. [43] P.L. Silva, C.M. Silva, L. Guimarães, J.R. Pliego, Acid-catalyzed transesterification and esterification in methanol: a theoretical cluster-continuum investigation of the mechanisms and free energy barriers, Theoretical Chemistry Accounts, 134 (2014). [44] R.G. PEARSON, Hard and Soft Acids and Bases, Journal of the American Chemical Society, 85 (1963) 3533-3539. [45] R.G.P.a.J. Songstad, Application of the Principle of Hard and Soft Acids and Bases to Organic Chemistry, Organic and Biological Chemistry, 89 (1966) 1827-1836. [46] M.A. Pacheco, Review of Dimethyl Carbonate (DMC) Manufacture and Its Characteristics as a Fuel Additive, Energy & Fuels, 11 (1997) 2-29.
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