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Chinese Chemical Letters 20 (2009) 973–976 www.elsevier.com/locate/cclet
A convenient preparation of ethoxymethoxymethane and its effect on the solubility of methanol/gasoline blends Shan Jian Cao, Ai You Hao *, Hong Yuan Sun, Tao Sun School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100, China Received 3 December 2008
Abstract Ethoxymethxoymethane (EMM) was conveniently prepared by acetalization of aqueous formaldehyde with methanol and ethanol in a batch reactive distillation mode using a cation-exchange resin catalyst for the first time. EMM was found to be a significant cosolvent of methanol/gasoline blends. # 2009 Ai You Hao. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved. Keywords: Ethoxymethoxymethane; Cation-exchange resin catalyst; Batch reactive distillation; Methanol/gasoline; Cosolvent
Along with worldwide energy lack and environmental pollution, methanol and ethanol as the alternative fuels are becoming more and more concerned. Methanol has more advantages compared with ethanol for its richer resource and lower cost [1]. However, the major issue with methanol/gasoline blends is the separation of the fuel, a heavier alcoholrich phase and a lighter gasoline-rich phase, at low temperatures [2]. The separation could be solved by adding additives into fuel blends, such as dimethoxymethane (DMM) and surfactant/cosurfactant pairs. But the low boiling point of DMM (42 8C) would cause an increase in the Reid Vapor Pressure (RVP), and the high boiling point of surfactant/cosurfactant pairs would result in residues. In this research, EMM as a new cosolvent of methanol/gasoline blends was conveniently prepared. EMM, with a boiling point of about 62 8C, was found to be an excellent cosolvent for methanol/gasoline blends. The boiling point of EMM is in the major boiling point range of gasoline, which might decrease the RVP and reduce the risk compared with that of DMM as cosolvent in methanol/gasoline blends. Some preparation of EMM have been involved in 1980s with some difficulties, such as reaction of (EtOCH2)2O with (R2BH)2 to gave EMM and R2BOEt [3], exchange reaction of DMM with diethoxymethane (DEM) in the presence of lewis acids to yield EMM [4]. Here, EMM was efficiently prepared by the reaction of formaldehyde with methanol and ethanol using cation-exchange resin Amberlyst 35 as the catalyst (Scheme 1). On the other hand, lots of advantages including ease of separation, mild reaction conditions and elimination of wastes could be achieved when cation-exchange resins were used as the catalyst [5]. The catalyst could be recovered and reused in subsequent reactions even without loss of activity.
* Corresponding author. E-mail address: [email protected] (A.Y. Hao). 1001-8417/$ – see front matter # 2009 Ai You Hao. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved. doi:10.1016/j.cclet.2009.03.025
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S.J. Cao et al. / Chinese Chemical Letters 20 (2009) 973–976
Scheme 1. The preparation of EMM.
1. Experimental The experiment on batch reactive distillation was carried out in a flask equipped with a spurs type of fractionating glass column. A methanol, ethanol and formaldehyde solution was first heated to the desired temperature, then Amberlyst 35 was added. CaCl2 was added to the distillation to separate DMM, DEM and EMM from water, alcohols and formaldehyde [6]. The oil phase was washed by CaCl2 saturated aqueous solution and then dried by CaCl2 to give anhydrous DMM, DEM and EMM. The batch distillation separation of DMM, DEM and EMM was conducted and the EMM fraction at 62 8C was collected. 1H NMR (300 MHz, D2O, d ppm): 1.12 (t, 3H, J = 7.1 Hz), 3.30 (s, 3H), 3.57 (q, 2H, J = 7.1 Hz), 4.60 (s, 2H); 13C NMR (300 MHz, D2O, d ppm): 95.5, 63.9, 54.8, 14.1; FTIR (n, cm 1): 2978, 2932, 2885, 1467, 1446, 1390, 1156, 1114, 1046. Each experiment was monitored and analyzed by gas chromatography. As shown in Table 1, the reaction time required could be reduced and the yield of EMM could be increased as the temperature, catalyst loading and mole ratio of MeOH:EtOH:HCHO increased.
Table 1 Reaction condition and results. Entry
Temperature (8C)
Catalyst loading (wt %)
MeOH:EtOH:HCHO (mol)
Time (h)
GC yielda (%)
1 2 3 4 5 6 7
70 80 90 80 80 80 80
5 5 5 2.5 7.5 5 5
1.25:1.25:1 1.25:1.25:1 1.25:1.25:1 1.25:1.25:1 1.25:1.25:1 1.05:1.05:1 1.5:1.5:1
3 2.5 2 3 2 3 2
39.0 40.4 41.4 38.5 42.3 37.6 43.3
a
Yields based on formaldehyde.
Fig. 1. The effect of EMM on the solubility of methanol/isooctane.
S.J. Cao et al. / Chinese Chemical Letters 20 (2009) 973–976
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2. Results and discussion The solubility of methanol/gasoline blends is influenced significantly by temperature, methanol concentration, gasoline characteristics (particularly, the aromatic content) [7], and the concentration of EMM as cosolvent. Isooctane and isooctane/toluene were used as models of the gasoline. The fuel blends were prepared by blending 5, 10, 15, and 20 vol.% of methanol with a specified amount of isooctane or isooctane/toluene or base gasoline. These fuel blends were designated as M5, M10, M15, and M20, respectively. It is apparent that EMM would provide effect on enhancing the solubility of the partially miscible systems (Figs. 1–3). Fig. 1 depicts the effect of EMM on the solubility of methanol/isooctane mixtures at different temperatures. Gasoline was represented by isooctane. This shows that the amount of EMM required decreases linearly with the temperature and that the slope is almost independent of the volume ratio of methanol to isooctane. The effect of addition of EMM on the solubility of methanol/isooctane/toluene mixtures is shown in Fig. 2. A solution of 90% isooctane and 10% toluene was for gasoline modeling. The experimental data indicated clearly that the higher the content of EMM, the higher is the solubility of methanol/isooctane/toluene blends. And less addition of
Fig. 2. The effect of EMM on the solubility of methanol/isooctane/toluene.
Fig. 3. The effect of added EMM on the solubility of methanol/gasoline.
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S.J. Cao et al. / Chinese Chemical Letters 20 (2009) 973–976
EMM was required compared that without toluene (Fig. 1). The solubility of the partially miscible systems would be enhanced by toluene. Fig. 3 depicts the effect of EMM on the solubility of methanol/gasoline. Without addition of EMM, M5 was completely miscible over the temperature range 20 to 20 8C, M10 did not keep stable only at 20 8C, M15 and M20 appeared phase separation at subzero temperatures. 2.2 vol.% of EMM was needed to make M10 stable at 20 8C. The miscibility of gasoline with methanol would be increased with the increasing amount of EMM. In conclusion, EMM was prepared by the reaction of formaldehyde with methanol and ethanol using a cationexchange resin as the catalyst in a batch reactive distillation mode with up to 43% yields of EMM. EMM, with a boiling point of about 62 8C, was found not only to be a fine industrial solvent similar with DMM and DEM, but also to be an excellent cosolvent for methanol/gasoline blends, especially at a high content of methanol up to 20% (v/v) even from 20 to 20 8C with low concentration of EMM. References [1] [2] [3] [4] [5] [6] [7]
Y. Wei, S. Liu, H. Li, Energy Fuels 22 (2008) 1254. D.W. Osten, N.J. Sell, Fuel 62 (1983) 268. G.B. Bagdasaryan, L. Sh. Airyan, M.G. Indzhikyan, Armyanskii Khimicheskii Zhurnal 33 (1980) 744. L.B. Gazizova, U.B. Imashev, R.S. Musavirov, Zhurnal Organic Khimiia 17 (1981) 275. Y. Zhang, W. Zhou, J. Ma, Natural Gas Chemical Industry 23 (1998) 22. A. Salabat, Fluid Phase Equilibria 257 (2007) 1. S. Nitirahardjo, H. Cheung, Energy Fuels 4 (1990) 303.
Chinese Chemical Letters 20 (2009) 973–976 www.elsevier.com/locate/cclet
A convenient preparation of ethoxymethoxymethane and its effect on the solubility of methanol/gasoline blends Shan Jian Cao, Ai You Hao *, Hong Yuan Sun, Tao Sun School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100, China Received 3 December 2008
Abstract Ethoxymethxoymethane (EMM) was conveniently prepared by acetalization of aqueous formaldehyde with methanol and ethanol in a batch reactive distillation mode using a cation-exchange resin catalyst for the first time. EMM was found to be a significant cosolvent of methanol/gasoline blends. # 2009 Ai You Hao. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved. Keywords: Ethoxymethoxymethane; Cation-exchange resin catalyst; Batch reactive distillation; Methanol/gasoline; Cosolvent
Along with worldwide energy lack and environmental pollution, methanol and ethanol as the alternative fuels are becoming more and more concerned. Methanol has more advantages compared with ethanol for its richer resource and lower cost [1]. However, the major issue with methanol/gasoline blends is the separation of the fuel, a heavier alcoholrich phase and a lighter gasoline-rich phase, at low temperatures [2]. The separation could be solved by adding additives into fuel blends, such as dimethoxymethane (DMM) and surfactant/cosurfactant pairs. But the low boiling point of DMM (42 8C) would cause an increase in the Reid Vapor Pressure (RVP), and the high boiling point of surfactant/cosurfactant pairs would result in residues. In this research, EMM as a new cosolvent of methanol/gasoline blends was conveniently prepared. EMM, with a boiling point of about 62 8C, was found to be an excellent cosolvent for methanol/gasoline blends. The boiling point of EMM is in the major boiling point range of gasoline, which might decrease the RVP and reduce the risk compared with that of DMM as cosolvent in methanol/gasoline blends. Some preparation of EMM have been involved in 1980s with some difficulties, such as reaction of (EtOCH2)2O with (R2BH)2 to gave EMM and R2BOEt [3], exchange reaction of DMM with diethoxymethane (DEM) in the presence of lewis acids to yield EMM [4]. Here, EMM was efficiently prepared by the reaction of formaldehyde with methanol and ethanol using cation-exchange resin Amberlyst 35 as the catalyst (Scheme 1). On the other hand, lots of advantages including ease of separation, mild reaction conditions and elimination of wastes could be achieved when cation-exchange resins were used as the catalyst [5]. The catalyst could be recovered and reused in subsequent reactions even without loss of activity.
* Corresponding author. E-mail address: [email protected] (A.Y. Hao). 1001-8417/$ – see front matter # 2009 Ai You Hao. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved. doi:10.1016/j.cclet.2009.03.025
974
S.J. Cao et al. / Chinese Chemical Letters 20 (2009) 973–976
Scheme 1. The preparation of EMM.
1. Experimental The experiment on batch reactive distillation was carried out in a flask equipped with a spurs type of fractionating glass column. A methanol, ethanol and formaldehyde solution was first heated to the desired temperature, then Amberlyst 35 was added. CaCl2 was added to the distillation to separate DMM, DEM and EMM from water, alcohols and formaldehyde [6]. The oil phase was washed by CaCl2 saturated aqueous solution and then dried by CaCl2 to give anhydrous DMM, DEM and EMM. The batch distillation separation of DMM, DEM and EMM was conducted and the EMM fraction at 62 8C was collected. 1H NMR (300 MHz, D2O, d ppm): 1.12 (t, 3H, J = 7.1 Hz), 3.30 (s, 3H), 3.57 (q, 2H, J = 7.1 Hz), 4.60 (s, 2H); 13C NMR (300 MHz, D2O, d ppm): 95.5, 63.9, 54.8, 14.1; FTIR (n, cm 1): 2978, 2932, 2885, 1467, 1446, 1390, 1156, 1114, 1046. Each experiment was monitored and analyzed by gas chromatography. As shown in Table 1, the reaction time required could be reduced and the yield of EMM could be increased as the temperature, catalyst loading and mole ratio of MeOH:EtOH:HCHO increased.
Table 1 Reaction condition and results. Entry
Temperature (8C)
Catalyst loading (wt %)
MeOH:EtOH:HCHO (mol)
Time (h)
GC yielda (%)
1 2 3 4 5 6 7
70 80 90 80 80 80 80
5 5 5 2.5 7.5 5 5
1.25:1.25:1 1.25:1.25:1 1.25:1.25:1 1.25:1.25:1 1.25:1.25:1 1.05:1.05:1 1.5:1.5:1
3 2.5 2 3 2 3 2
39.0 40.4 41.4 38.5 42.3 37.6 43.3
a
Yields based on formaldehyde.
Fig. 1. The effect of EMM on the solubility of methanol/isooctane.
S.J. Cao et al. / Chinese Chemical Letters 20 (2009) 973–976
975
2. Results and discussion The solubility of methanol/gasoline blends is influenced significantly by temperature, methanol concentration, gasoline characteristics (particularly, the aromatic content) [7], and the concentration of EMM as cosolvent. Isooctane and isooctane/toluene were used as models of the gasoline. The fuel blends were prepared by blending 5, 10, 15, and 20 vol.% of methanol with a specified amount of isooctane or isooctane/toluene or base gasoline. These fuel blends were designated as M5, M10, M15, and M20, respectively. It is apparent that EMM would provide effect on enhancing the solubility of the partially miscible systems (Figs. 1–3). Fig. 1 depicts the effect of EMM on the solubility of methanol/isooctane mixtures at different temperatures. Gasoline was represented by isooctane. This shows that the amount of EMM required decreases linearly with the temperature and that the slope is almost independent of the volume ratio of methanol to isooctane. The effect of addition of EMM on the solubility of methanol/isooctane/toluene mixtures is shown in Fig. 2. A solution of 90% isooctane and 10% toluene was for gasoline modeling. The experimental data indicated clearly that the higher the content of EMM, the higher is the solubility of methanol/isooctane/toluene blends. And less addition of
Fig. 2. The effect of EMM on the solubility of methanol/isooctane/toluene.
Fig. 3. The effect of added EMM on the solubility of methanol/gasoline.
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S.J. Cao et al. / Chinese Chemical Letters 20 (2009) 973–976
EMM was required compared that without toluene (Fig. 1). The solubility of the partially miscible systems would be enhanced by toluene. Fig. 3 depicts the effect of EMM on the solubility of methanol/gasoline. Without addition of EMM, M5 was completely miscible over the temperature range 20 to 20 8C, M10 did not keep stable only at 20 8C, M15 and M20 appeared phase separation at subzero temperatures. 2.2 vol.% of EMM was needed to make M10 stable at 20 8C. The miscibility of gasoline with methanol would be increased with the increasing amount of EMM. In conclusion, EMM was prepared by the reaction of formaldehyde with methanol and ethanol using a cationexchange resin as the catalyst in a batch reactive distillation mode with up to 43% yields of EMM. EMM, with a boiling point of about 62 8C, was found not only to be a fine industrial solvent similar with DMM and DEM, but also to be an excellent cosolvent for methanol/gasoline blends, especially at a high content of methanol up to 20% (v/v) even from 20 to 20 8C with low concentration of EMM. References [1] [2] [3] [4] [5] [6] [7]
Y. Wei, S. Liu, H. Li, Energy Fuels 22 (2008) 1254. D.W. Osten, N.J. Sell, Fuel 62 (1983) 268. G.B. Bagdasaryan, L. Sh. Airyan, M.G. Indzhikyan, Armyanskii Khimicheskii Zhurnal 33 (1980) 744. L.B. Gazizova, U.B. Imashev, R.S. Musavirov, Zhurnal Organic Khimiia 17 (1981) 275. Y. Zhang, W. Zhou, J. Ma, Natural Gas Chemical Industry 23 (1998) 22. A. Salabat, Fluid Phase Equilibria 257 (2007) 1. S. Nitirahardjo, H. Cheung, Energy Fuels 4 (1990) 303.