JP2009062467A - Fuel composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel composition that can make dehydration treatment of a condensed bio-ethanol needless and can be mixed directly with the fuel without esterification of the ethanol. <P>SOLUTION: The fuel composition is a fuel containing moist ethanol and contains a 1.5-30.0 wt.% nonionic surfactant represented by general formula (1), wherein, R is a 12-18C alkyl- or alkenyl group and EO is ethylene oxide (CH<SB>2</SB>CH<SB>2</SB>O), and an average addition molar number m is 3-20. A 0.1-30.0 wt.% anionic surfactant represented by general formula (2) may also be contained. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a fuel composition useful for preventing precipitation of water due to addition of hydrous ethanol to fuel such as gasoline.

  Since plant-derived bioethanol is useful for reducing carbon dioxide emissions required by the Kyoto Protocol, attempts are being made to use it as an alternative fuel to gasoline. Since it is expected that problems will occur if ethanol is used as it is in an existing gasoline engine vehicle, ethanol-mixed gasoline in which ethanol is added to gasoline is used. Mixed gasoline (E3 fuel) or ethanol in which 3 wt% ethanol is mixed A mixed gasoline (E10 fuel) in which 10 wt% is mixed is used.

  However, when bioethanol is mixed with gasoline and used as a fuel for automobiles or the like, gasoline and ethanol may be phase-separated in severe winter due to moisture remaining in ethanol or inevitably contained water. There is a problem of corroding the fuel tank. For this reason, it is necessary to reduce the amount of water in ethanol as much as possible so that gasoline and ethanol do not phase-separate.

Therefore, conventionally, in a normal distillation step (concentration step) for producing ethanol, the purity of ethanol can be concentrated only to about 90%, and therefore a zeolite membrane or the like is used to remove the remaining water. Dehydrating and mixing this directly with gasoline, or by reacting ethanol with an olefin such as isobutene to produce ether compounds such as ethyl tertiary butyl ether (ETBE), which are mixed with gasoline (See Patent Document 1 etc.).
Japanese Patent Laying-Open No. 2005-187706

  However, the conventional method of directly mixing ethanol requires a large-scale membrane dehydration apparatus or the like for dehydration, which has a disadvantage of enormous cost. Moreover, in the method of mixing ETBE, since chemical treatment for reacting ethanol with olefins such as isobutene is required, the chemical treatment equipment is enormously costly and requires a lot of energy to perform the chemical treatment. There was an inconvenience.

  Moreover, water-containing ethanol and gasoline can be mixed uniformly when the ethanol content is 40 wt% or more at normal temperature, but when the content is less than that normally used as fuel, ethanol is not uniformly mixed and separation occurs. It has also been confirmed.

  The present invention has been made in view of such circumstances, and eliminates the need for dehydration of concentrated bioethanol and costs and energy associated with chemical processing by directly mixing ethanol with fuel without esterification. The main object is to provide a fuel composition capable of eliminating consumption and further capable of stably dispersing ethanol in the fuel.

  We have reverse micelles that are self-assembled by a surfactant added in oil, the hydrophilic groups of the surfactant are arranged towards the aqueous phase of the micelle inner shell, called the water pool, It has a unique structure in which hydrophobic groups are arranged toward the outer oil phase. By adjusting the type and amount of surfactant, water contained in the oil is solubilized in the water pool and bonded. Dehydration process that can be strongly bound as water (bound water), and free water existing in oil can be eliminated or greatly reduced. In addition, the inventors have obtained knowledge that it is possible to suppress the precipitation of water without esterifying ethanol, and the present invention has been completed.

  That is, the fuel composition according to the present invention is characterized by containing 1.5 to 30.0 wt% of a nonionic surfactant represented by the following general formula (1) in a fuel to which hydrous ethanol is added. .

ただし、Ｒは、炭素数１２〜１８のアルキル基又はアルケニル基であり、ＥＯはエチレンオキサイド（ＣＨ_２ＣＨ_２Ｏ)を示し、平均付加モル数ｍは３〜２０である。

Here, R is an alkyl or alkenyl group having 12 to 18 carbon atoms, EO represents an ethylene oxide _{(CH 2 CH} 2 O), average addition mole number m is 3-20.

  Further, the fuel composition may contain 0.1 to 30.0 wt% of an anionic surfactant represented by the following general formula (2) in a solution to which hydrous ethanol is added.

  Here, the purity of ethanol easily obtained in the distillation step (concentration step) for producing ethanol is about 90%, and if it is desired to obtain a purity higher than this, a dehydrator and chemical treatment are required, resulting in a large cost. Therefore, it is preferable that water-containing ethanol having a water content of about 10 wt% can be directly added to gasoline. For this reason, it is preferable that the fuel to which water-containing ethanol is added is a fuel to be added so that 10 wt% or less of water-containing ethanol is 3 to 30 wt%. Such a fuel composition is particularly useful when gasoline is used as the fuel.

  As described above, according to the present invention, free water existing in fuel can be obtained by solubilizing and constraining water content in reverse micelles formed by a surfactant added together with water-containing ethanol. It is possible to eliminate or drastically reduce water, and it is possible to suppress the precipitation of water without performing a dehydration process using a dehydrator and without performing a chemical process. For this reason, the water-containing ethanol obtained in the conventional distillation step (concentration step) can be directly mixed with the fuel without subjecting it to a dehydration treatment for further increasing the purity and without subjecting the water-containing ethanol to esterification. It becomes possible. Therefore, it is possible to suppress a great deal of cost and energy consumption. Further, even when the amount of ethanol added is small, it is possible to stably disperse the water-containing ethanol in the fuel.

  Embodiments of the present invention will be described below.

The fuel composition of the present invention contains a fuel, water-containing ethanol, and a surfactant.
The fuel is not particularly limited as long as the following surfactant having solubility in water can form reverse micelles in the fuel, but gasoline is particularly suitable.
As the water-containing ethanol, in the distillation step (concentration step) for producing bioethanol, the ethanol purity is about 90 wt% (water content is about 10 wt%), and therefore water-containing ethanol having a water content of 10 wt% or less is used. Good.

  As the surfactant, a nonionic surfactant represented by the following general formula (1) and an anionic surfactant (AOT) represented by the general formula (2) are used.

Here, R is a linear or branched alkyl group or alkenyl group having 12 to 18 carbon atoms, EO represents an addition unit of ethylene oxide (CH ₂ CH ₂ O), and average added mole number m Is preferably 3-20.
The reason why the lower limit of the carbon number is 12 is that micelles cannot be formed if the carbon number becomes smaller than this. Moreover, the upper limit of the carbon number is 18 because there is a disadvantage that the surfactant is precipitated at room temperature when the carbon number is larger than this. In addition, when the average added mole number m is smaller than 3, the ability to solubilize water in the reverse micelle becomes small, and the water cannot be solubilized and bound.

In the following, as typical examples when R is an alkyl group, C ₁₂ (EO) _3, C ₁₂ (EO) ₅ , C ₁₂ (EO) ₉ , C ₁₆ (EO) ₅ , C ₁₆ (EO) ₇ , C ₁₆ (EO) ₁₅ , C ₁₆ (EO) ₂₀ , C ₁₆ (EO) ₂₅ is used, and C ₁₈ (EO) ₆ is used as a typical example when R is an alkenyl group.

  As shown in FIG. 1, as a fuel, water-containing ethanol obtained by adding 10 wt% water to ethanol is prepared as a model substance of water-containing bioethanol, and the surfactant is added to gasoline to form reverse micelles. And it prepared by mixing the prepared hydrous ethanol and the gasoline which added surfactant with stirring at room temperature.

  First, a water-containing ethanol mixed fuel to which a surfactant was added was prepared at room temperature, and it was examined whether or not it was uniformly mixed visually. Moreover, as a comparative example, among the derivatives of polyoxyethylene hydrogenated castor oil represented by the following general formula (Chemical Formula 4), derivatives having an average added mole number (E) of ethylene oxide of 5, 10, 20, 80, 100 ( HCO-5, HCO-10, HCO-20, HCO-80, HCO-100) were added to gasoline, and 10 wt% aqueous ethanol was mixed and stirred at room temperature. The result is shown in FIG. In the table, ◯ indicates that a homogeneous phase can be prepared at room temperature, and x indicates that a homogeneous phase cannot be prepared at room temperature.

From these results, among AOT which is an anionic surfactant and Cn (EO) m which is a nonionic surfactant, n is in the range of 12 to 16, m is in the range of 3 to 20, A homogeneous mixing state was obtained for C ₁₈ (EO) ₆ which is a saturated nonionic surfactant.

Among these, AOT, C ₁₂ (EO) ₃ , C ₁₆ (EO) ₇ , and C ₁₈ (EO) ₆ were further examined in detail. By sequentially changing the addition amount of 10 wt% water-containing ethanol and the addition amount of surfactant, a region where water-containing ethanol is uniformly mixed with gasoline at room temperature (mixing region) and a region where water-containing ethanol is not mixed uniformly (non-mixing region) Examined. FIG. 3 shows a trigonometric phase diagram when 10 wt% aqueous ethanol is added up to 30 wt%. In this ternary phase diagram, the unmixed area indicates the area on the left side of the boundary indicated by the solid line, and the mixed area indicates the area on the right side of the boundary.

When the surfactant is AOT, C ₁₂ (EO) ₃ , C ₁₆ (EO) ₇ , the range of the surfactant addition amount in the non-mixing region when the addition amount of 10 wt% water-containing ethanol is sequentially changed FIG. 4 shows the results of examining the range of the surfactant addition amount in the mixed region. Moreover, the examination result of the system at the time of using _C18 (EO) ₆ as an unsaturated surfactant is shown in FIG.

  As is clear from these results, when the amount of hydrous ethanol added is 3 to 30 wt%, when the surfactant is AOT, the composition of the surfactant is 0.1 to 30.0 wt%. It is useful to set in the range, and when the surfactant is a nonionic surfactant, it is useful to set the composition of the surfactant in the range of 1.5 to 30.0 wt%. I understand that.

The above examination was made on the miscibility with gasoline at room temperature. Next, the coagulation temperature of water was measured from the DSC temperature drop measurement for the composition of the obtained homogeneous phase.
FIG. 6 shows the measurement results obtained by changing the type and addition amount of the surfactant in the mixed gasoline obtained by mixing 10 wt% hydrous ethanol with 3 wt% of the gasoline.

From this result, it is confirmed that the freezing point is shifted to a low temperature side, and water is solubilized in the reverse micelle formed by the surfactant to form a strongly bound state. In particular, in C ₁₂ (EO) ₃ , the freezing point has reached −40 ° C. or lower, and it can be seen that free water disappears and water is strongly bound.

Next, the influence of the difference in the amount of hydrous ethanol added to gasoline was investigated. FIG. 7 shows the measurement results when the surfactant is C ₁₂ (EO) ₃ . The freezing point can be kept low in any part of the mixed region of the trigonometric phase diagram, and it can be confirmed that free water has been eliminated.

In particular, in gasoline containing 3 wt% hydrous ethanol to which 3.8 wt% C ₁₂ (EO) ₃ is added, as shown in FIG. 8, it is possible to lower the freezing point to near −50 ° C., and 3 wt% hydrous ethanol is contained. It can be seen that it is optimal to add 3.8 wt% of C ₁₂ (EO) ₃ in gasoline.

In addition, when the surfactant is C ₁₆ (EO) ₅ and the water content in ethanol is changed to 10 wt%, 7 wt%, 5 wt%, and 3 wt%, the DSC when the water content in the ethanol is changed to 3 wt% FIG. 9 shows the measurement results for each of 10 wt% and 30 wt%.

It can be seen that as the amount of ethanol added increases, the freezing point shifts lower, and the water is strongly bound and hardly precipitated. Further, even in gasoline containing 3 wt% hydrous ethanol to which C ₁₆ (EO) ₅ is added, when the addition amount is 5.7 wt%, the freezing point is lowered to −20 ° C. or lower as shown in FIG. It has been confirmed.

  In AOT, the binding force of water is stronger than in the case of using a nonionic surfactant. When 4.73 wt% of AOT is added to E10 gasoline, the measurement result shown in FIG. 11 is obtained. The freezing point could not be found even at -50 ° C.

  Therefore, by adding a surfactant to the fuel to which water-containing ethanol has been added, water can be solubilized by the reverse micelles formed by the surfactant and precipitation can be suppressed. Can be mixed. Therefore, it is not necessary to perform a dehydration process using a dehydrator to increase the purity of hydrous ethanol, and it is not necessary to perform a chemical process for performing esterification. Can be eliminated. Further, even when the amount of ethanol added is small, it is possible to stably disperse the water-containing ethanol in the fuel.

Next, commercially available gasoline, mixed gasoline (E3) in which 3 wt% ETBE is mixed with gasoline, 10 wt% water-containing ethanol is added to the gasoline to 3 wt%, and AOT is added at 1.0 wt%. The fuel consumption was compared between the fuel composition and the fuel composition in which 10 wt% aqueous ethanol was added to gasoline to 3 wt% and C ₁₂ (EO) ₃ was added 5.7 wt%.

In the measurement of fuel consumption, a soundproof engine engine (model: GA-2000SSM, engine: GM181 257 kW / 3000 min ⁻¹ , rated output: 1.7 kVA, rated voltage: 100 V, rated current: 17 A, frequency: 50 Hz, phase number : Singular) was rotated at the rated value, and the time consumed by 1 kg of fuel was measured. The result is shown in FIG.

In addition, when only gasoline is used, when commercially available E3 gasoline in which 3 wt% ETBE is mixed with gasoline is used, when 3 wt% of 100% ethanol containing no water is added to gasoline, 10% % hydrous ethanol was added 3 wt% in gasoline, when adding 1.0 wt% of AOT as the surfactant, 10% water-containing ethanol was added 3 wt% in gasoline, the _C 13 _{(EO) 3} as a surfactant 5. Each of the cases where 7 wt% was added was subjected to a combustion test.

In the combustion test, when the engine speed is kept constant at 2000 rpm (in the case of idling) with a 50 cc motorcycle (model: HONDA TODAY, engine type: AF67E, engine type: single cylinder), the engine speed is changed from 2000 rpm to 5000 rpm. When the engine speed is changed (accelerated) and when the engine speed is changed from 2000 rpm to 8000 rpm (rapid acceleration), the exhaust gas temperature (° C FT) and oxygen partial pressure ( % O ₂ ), discharged CO concentration (ppm CO), discharged NO concentration (ppm NO), discharged NO ₂ concentration (ppm NO ₂ ), total value of NO concentration and NO ₂ concentration (ppm NOx), The concentration (ppm HC) of hydrocarbon discharged without burning was measured.

FIG. 13 shows the measurement results when burning only with gasoline, FIG. 14 shows the measurement results when burning commercially available E3 gasoline, and 3 wt% of 100% ethanol containing no water with respect to gasoline. FIG. 15 shows the measurement result when added, and FIG. 16 shows the measurement result when added with 3 wt% of 10% aqueous ethanol and 1.0 wt% of AOT as a surfactant. FIG. 16 shows the surface activity of 3 wt% of 10% aqueous ethanol. FIG. 17 shows the measurement result when 5.7 wt% of C ₁₃ (EO) ₃ was added as an agent.

  In the figure, “over” indicates a case where the concentration becomes 10,000 ppm or more and measurement is impossible in the detection range of the commercially available detector used. Each numerical value column indicates a value sampled every predetermined time, and the lower numerical value indicates a numerical value closer to a steady state at the target rotational speed.

  As can be seen from this result, even when a surfactant is added to a mixed gasoline mixed with water-containing ethanol, it functions sufficiently as a fuel, and in terms of fuel economy, it tends to be better to add a surfactant. In addition, in the combustion experiment, the fuel to which the surfactant was added tended to emit less CO and hydrocarbons.

FIG. 1 is a block diagram illustrating a method for preparing a water-containing ethanol mixed gasoline to which a surfactant is added. FIG. 2 is a table showing the result of visual determination as to whether or not a surfactant was further added to the mixed gasoline to which 10 wt% water-containing ethanol was added and mixed uniformly at room temperature. FIG. 3 shows a trigonometric phase diagram of gasoline, water-containing ethanol, and surfactant, (a) shows the case where AOT is used as the surfactant, and (b) shows C ₁₃ (EO) ₃ as the surfactant. (C) shows the case where C ₁₆ (EO) ₇ is used as the surfactant, and (d) shows the case where C ₁₈ (EO) ₆ of unsaturated alkyl is used. FIG. 4 is a table in which the unmixed region and the mixed region read from the trigonometric phase diagram are digitized. (A) represents a gasoline-10 wt% water-containing ethanol-AOT system, and (b) represents a gasoline-10 wt% water content. Ethanol-C ₁₃ (EO) ₃ system is represented, and (c) represents gasoline-10 wt% hydrous ethanol-C ₁₆ (EO) ₇ system. FIG. 5 shows the result of determining the presence or absence of a homogeneous phase when the ratio of each element is changed in the C ₁₈ (EO) ₆ system of gasoline-10 wt% hydrous ethanol-unsaturated alkyl shown in FIG. It is a table to represent. FIG. 6 is a diagram showing DSC measurement results in a mixed gasoline obtained by mixing 3 wt% of 10 wt% aqueous ethanol with respect to gasoline while changing the type and amount of surfactant. FIG. 7 is a diagram showing DSC measurement results based on differences in the amount of hydrous ethanol added to gasoline when the surfactant is C ₁₂ (EO) ₃ and corresponding measurement points in the trigonometric phase diagram. FIG. 8 is a diagram showing DSC measurement results of gasoline containing 3 wt% of water-containing ethanol to which 3.8 wt% of C ₁₂ (EO) ₃ was added. FIG. 9 shows the DSC when the surfactant is C ₁₆ (EO) ₅ and the water content in ethanol is changed to 10 wt%, 7 wt%, 5 wt%, and 3 wt%. It is a diagram which shows the result measured about each case which was 3 wt%, 10 wt%, and 30 wt%. FIG. 10 is a diagram showing a DSC measurement result of gasoline containing 3 wt% of water-containing ethanol to which C ₁₆ (EO) ₅ is added. FIG. 11 is a diagram showing DSC measurement results when 4.73 wt% of AOT is added to a mixed gasoline in which 10 wt% of water-containing ethanol is mixed with 10 wt% of gasoline. FIG. 12 is a table showing the results of measuring the fuel consumption of various fuels. FIG. 13 is a table showing measurement results of a combustion test in which only gasoline was burned. FIG. 14 is a table showing measurement results of a combustion test in which commercial gasoline (E3) in which 3 wt% ETBE is mixed with gasoline is burned. FIG. 15 is a table showing measurement results of a combustion test in which mixed gasoline in which 3% by weight of 100% ethanol not containing water was added to gasoline was burned. FIG. 16 is a table showing measurement results of a combustion test in which a fuel obtained by adding 1.0 wt% of AOT as a surfactant to a mixed gasoline in which 3 wt% of 10 wt% aqueous ethanol is mixed with gasoline is burned. FIG. 17 is a table showing measurement results of a combustion test in which a fuel obtained by adding 5.7 wt% of C ₁₂ (EO) ₃ as a surfactant to a mixed gasoline obtained by mixing 10 wt% hydrous ethanol with 3 wt% of gasoline is used. It is.

Claims (4)

A fuel composition comprising 1.5 to 30.0 wt% of a nonionic surfactant represented by the following general formula (1) in a fuel to which hydrous ethanol is added.

However, R is a C12-C18 alkyl group or alkenyl group, EO shows ethylene oxide, and the average addition mole number m is 3-20. A fuel composition comprising 0.1 to 30.0 wt% of an anionic surfactant represented by the following general formula (2) in a fuel to which hydrous ethanol is added.

The fuel composition according to claim 1 or 2, wherein the fuel to which water-containing ethanol is added is a fuel to which water-containing ethanol having a water content of 10 wt% or less is added so as to be 3 to 30 wt%. The fuel composition according to any one of claims 1 to 3, wherein the fuel is gasoline.

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