Fuel with oil film, and immiscible oil

Abstract

To provide a fuel that can be stored in a normal fuel tank while suppressing evaporation of ammonia, and an immiscible oil for obtaining the fuel.SOLUTION: A fuel 70 with an oil film of the present disclosure comprises: a fuel solution 50 containing ammonia and methanol; and an immiscible oil 60 that is not miscible with the fuel solution 50. A density of the immiscible oil 60 has a density less than the density of the fuel solution 50. The immiscible oil 60 remains above a liquid surface 52 of the fuel solution 50 and suppresses evaporation of ammonia in the fuel solution 50.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to oil-filmed fuels and immiscible oils and greases. [Background technology]

[0002] Ammonia does not emit carbon dioxide when burned, so it has been attracting attention as a fuel that can achieve carbon neutrality. Ammonia can be obtained, for example, by reacting hydrogen obtained by electrolyzing water using electricity generated from renewable energy with nitrogen, which accounts for approximately 80% of the air. Ammonia itself is a gas at room temperature under atmospheric pressure (0.1 MPa), so its volume is large and it is difficult to use it as an automobile fuel. In addition, to liquefy it, it must be pressurized to 1 MPa (25°C), so a pressure-resistant container is required.

[0003] Although methanol is expected to be a fuel that can achieve carbon neutrality, when used as a fuel for automobiles, it emits carbon dioxide while the automobile is in operation (on-board). In addition, methanol is a colorless, transparent liquid with an alcohol odor, and is addictive.

[0004] In view of the above-mentioned properties of ammonia and methanol, fuel solutions containing ammonia and methanol have been considered.

[0005] Patent Document 1 discloses a fuel solution containing ammonia and methanol to improve the flame retardancy of ammonia. Specific examples of the fuel solution disclosed include fuel solutions containing 70 mass % ammonia and 30 mass % methanol, 50 mass % ammonia and 50 mass % methanol, and 30 mass % ammonia and 70 mass % methanol.

[0006] Patent Document 2 discloses a fuel solution containing ammonia water (ammonia hydrate) and methanol.

[0007] Patent Document 3 discloses a fuel solution containing 5 to 25 mass % ammonia, the remainder being methanol. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] JP 2022-171351 A [Patent Document 2] International Publication No. 2012 / 050127 [Patent Document 3] JP 2000-110510 A [Non-patent literature]

[0009] [Non-Patent Document 1] CRC Handbook, Editor-in-Chief. WM Haynes, CRC handbook of chemistry and physics, 97th ed., CRC Press, 2016-2017. Summary of the Invention [Problem to be solved by the invention]

[0010] When the fuel solution contains 30 mass % or more of ammonia, as in the fuel solution disclosed in Patent Document 1, a large amount of ammonia evaporates under atmospheric pressure (0.1 MPa), making it difficult to store the fuel solution in a normal fuel tank.

[0011] When ammonia is contained at 25 mass % or less, such as in the fuel solution disclosed in Patent Document 3, the vapor pressure of ammonia is small at 0.1 MPa, but it is difficult to completely prevent the evaporation of ammonia.

[0012] Even in a hydrated fuel solution containing ammonia water and methanol, such as the fuel solution of Patent Document 2, evaporation of ammonia is unavoidable, and since the fuel solution contains water, the heat of combustion is reduced.

[0013] The present disclosure has been made to solve the above problems. The present disclosure aims to provide a fuel that can be stored in a normal fuel tank while suppressing the evaporation of ammonia, and an immiscible oil for obtaining the fuel. In this specification, the term "normal fuel tank" refers to a tank that does not have a mechanism for pressurizing the inside of the tank, and corresponds to, for example, a gasoline tank for an automobile. [Means for solving the problem]

[0014] In order to achieve the above object, the present inventors have conducted intensive research and have completed the oil film-attached fuel and the immiscible oil of the present disclosure. The oil film-attached fuel and the immiscible oil of the present disclosure include the following aspects. <Aspect 1> A fuel solution containing ammonia and methanol, and Immiscible oils and fats that are not miscible with the fuel solution Including, The density of the immiscible oil or fat is less than the density of the fuel solution; Fuel with oil film. <Aspect 2> 2. The oil-film-coated fuel according to claim 1, wherein the immiscible oil is a silicone oil. <Aspect 3> The density of the immiscible oil or fat is 0.770 g / cm 3 3. The oil film-coated fuel according to claim 1 or 2, wherein: <Aspect 4> 4. The oil-film-attached fuel according to any one of Aspects 1 to 3, wherein an ammonia concentration in the fuel solution is 0.1 to 20.0 mass %. <Aspect 5> An immiscible oil that is not miscible with a fuel solution containing ammonia and methanol, has a density smaller than that of the fuel solution, and remains on the liquid surface of the fuel solution to suppress evaporation of ammonia in the fuel solution. Effect of the Invention

[0015] According to the present disclosure, it is possible to provide a fuel with an oil film, which can be stored in a normal fuel tank by suppressing the evaporation of ammonia in the fuel solution through the retention of immiscible oil on the liquid surface of the fuel solution.

[0016] In addition, according to the present disclosure, it is possible to provide an immiscible oil that is immiscible with a fuel solution containing ammonia and methanol and has a smaller density than the fuel solution, and can be retained on the liquid surface of the fuel solution to suppress evaporation of ammonia from the fuel solution. [Brief description of the drawings]

[0017] [Figure 1] FIG. 1 is an explanatory diagram showing an example of a state in which the oil film-covered fuel of the present disclosure is stored in a normal container. [Diagram 2] FIG. 2 is an explanatory diagram showing an example of the structural formula of silicone oil. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Hereinafter, embodiments of the oil film-attached fuel and the immiscible oil of the present disclosure will be described. Note that the following embodiments do not limit the oil film-attached fuel and the immiscible oil of the present disclosure.

[0019] Without being bound by theory, the findings of the present inventors regarding the reason why the oil-film-coated fuel of the present disclosure can suppress the evaporation of ammonia from the fuel solution and can be stored in a normal fuel tank will be explained with reference to the drawings.

[0020] 1 is an explanatory diagram showing an example of a state in which the oil-film-coated fuel of the present disclosure is stored in a normal tank. The tank 10 includes a main body 20 and a supply unit 30. A lid 40 is attached to the supply unit 30. The tank 10 does not include a mechanism for pressurizing the inside of the tank 10, and the lid 40 only needs to have a sealability sufficient to prevent leakage of liquid inside the tank 10 when the tank 10 is inverted or tilted. The tank 10 may include, for example, a fuel solution outlet having an opening and closing valve at the bottom of the main body 20.

[0021] When the fuel solution 50 and the immiscible oil 60 are supplied from the supply unit 30 to the inside of the tank 10, the immiscible oil 60 remains on the liquid surface 52 of the fuel solution 50, forming a fuel 70 with an oil film, and the immiscible oil 60 covers the fuel solution 50. This is because the fuel solution 50 and the immiscible oil 60 are not miscible with each other, and the density of the immiscible oil 60 is smaller than the density of the fuel solution 50. By forming the fuel 70 with an oil film, the immiscible oil 60 can suppress the evaporation of ammonia in the fuel solution 50.

[0022] The constituent elements of the oil film-attached fuel and the immiscible oil of the present disclosure, which have been completed based on the findings described above, will be described below.

[0023] 《Fuel with oil film》 The oil film-attached fuel of the present disclosure includes a fuel solution and an immiscible oil or fat. Each of these will be described below.

[0024] <Fuel solution> The fuel solution is ammonia (NH 3 ) and methanol (CH 3 OH). Ammonia produced by a known method may be used, or a commercially available product may be used. An example of a known production method is a method in which hydrogen obtained by electrolyzing water using electricity generated by renewable energy is reacted with nitrogen, which is contained in the air at about 80%. Methanol produced by a known method may be used, or a commercially available product may be used. An example of a known production method is a method in which carbon monoxide produced from coal and / or natural gas is reacted with hydrogen under high pressure and high temperature using a copper oxide-zinc oxide / alumina composite oxide as a catalyst.

[0025] The ammonia concentration in the fuel solution is not particularly limited, but is preferably 0.1 to 20.0% by mass based on the entire fuel solution. From the viewpoint of substantially recognizing the effect of adding ammonia to the fuel solution, the ammonia concentration may be 0.1% by mass or more, 0.5% by mass or more, or 1.0% by mass or more. From the viewpoint of preventing ammonia from evaporating from the fuel solution, the ammonia concentration may be 30.0% by mass or less, 29.0% by mass or less, 25.0% by mass or less, 20.0% by mass or less, 15.3% by mass or less, 15.0% by mass or less, 10.0% by mass or less, 8.3% by mass or less, 8.0% by mass or less, 5.0% by mass or less, or 4.3% by mass or less.

[0026] In the fuel solution, the remainder of the ammonia may typically be methanol. As long as the effects of the present invention are not impaired, the fuel solution may contain substances other than ammonia and methanol in an amount of 5.0% by mass or less, 3.0% by mass or less, 1.0% by mass or less, 0.5% by mass or less, or 0.1% by mass or less based on the entire fuel solution. Substances other than ammonia and methanol are typically substances that are inevitably generated during the production of ammonia and / or methanol.

[0027] 〈Immiscible oil and fat〉 The immiscible oil and fat is not miscible with the fuel solution. "Not miscible" means not mixing with each other and separating. Also, the density of the immiscible oil and fat is smaller than the density of the fuel solution. As a result, not only do the fuel solution and the immiscible oil and fat simply separate, but also, in combination with the action of gravity, they form layers with each other, and the immiscible oil and fat stays on the liquid surface of the fuel solution and covers the liquid surface of the fuel solution.

[0028] From the viewpoint of the immiscible oil and fat staying on the liquid surface of the fuel solution, the smaller the density of the immiscible oil and fat, the more preferable. When the ammonia content of the fuel solution increases, the density of the fuel solution decreases. Therefore, the density of the immiscible oil and fat is typically 0.780 g / cm 3 or less, 0.775 g / cm 3 or less, 0.770 g / cm 3 or less, 0.765 g / cm 3 or less, 0.760 g / cm3 or less than 0.755g / cm 3 It is preferable that:

[0029] The thickness of the oil film composed of the immiscible oil and fat remaining on the liquid surface of the fuel solution may be appropriately determined depending on the ammonia concentration in the fuel solution, the type of the immiscible oil and fat, and / or the capacity of the tank. If the oil film thickness is 0.3 cm or more, 0.5 cm or more, 0.7 cm or more, or 1.0 cm or more, it is advantageous to suppress the evaporation of ammonia. If the oil film thickness is 2.0 cm or less, 1.7 cm or less, 1.5 cm or less, or 1.3 cm or less, it is advantageous to ensure the space occupied by the fuel solution in the tank.

[0030] The immiscible oil is typically a hydrophobic oil, and preferably has low volatility. The immiscible oil may be, for example, silicone oil. As long as it satisfies the requirements of the immiscible oil, there is no particular restriction on the structure of the silicone oil. Figure 2 is an explanatory diagram showing an example of the structural formula of silicone oil.

[0031] The immiscible oils and fats described so far are not miscible with the fuel solution, have a lower density than the fuel solution, and remain on the liquid surface of the fuel solution, suppressing the evaporation of ammonia in the fuel solution.

[0032] 《Transform》 In addition to the above, the oil film-covered fuel and the immiscible oil of the present disclosure can be modified in various ways within the scope of the claims. For example, a device can be constructed in which the oil film-covered fuel of the present disclosure is contained in a non-pressurized container. EXAMPLES

[0033] The oil film-attached fuel and the immiscible oil of the present disclosure will be described in more detail below with reference to examples and comparative examples. Note that the oil film-attached fuel and the immiscible oil of the present disclosure are not limited to the conditions used in the following examples.

[0034] Sample preparation Each sample was prepared as follows.

[0035] Example 1 A fuel solution was prepared by mixing ammonia with methanol. The ammonia concentration was 15.3 mass% and the remainder was methanol. The density of the fuel solution was 0.779 g / cm 3 The density of the fuel solution was calculated by measuring the mass and volume of the fuel solution. Silicone oil (KF-96L-0.65CS, manufactured by Shin-Etsu Chemical Co., Ltd.) was mixed into this fuel solution to obtain a sample of fuel with an oil film. The structure of the silicone oil is shown in Figure 2. The thickness of the oil film was 1.0 cm. The density of the silicone oil was 0.760 g / cm 3 It was.

[0036] Example 2 A sample of Example 2 was obtained in the same manner as Example 1, except that the ammonia concentration was 8.7 mass %. The density of the fuel solution was 0.781 g / cm 3 The thickness of the oil film was 1.0 cm.

[0037] Example 3 A sample of Example 3 was obtained in the same manner as Example 1, except that the ammonia concentration was 4.3 mass %. The density of the fuel solution was 0.783 g / cm 3 The thickness of the oil film was 1.0 cm.

[0038] Example 4 A sample of Example 4 was obtained in the same manner as Example 1, except that the ammonia concentration was 1.0 mass %. The density of the fuel solution was 0.789 g / cm 3 The thickness of the oil film was 1.0 cm.

[0039] Example 5 A sample of Example 5 was obtained in the same manner as Example 1, except that the ammonia concentration was 0.1 mass %. The density of the fuel solution was 0.792 g / cm 3 The thickness of the oil film was 1.0 cm.

[0040] Comparative Example 1 Methanol used in Example 1 was prepared, and a sample of Comparative Example 1 was obtained as it was without mixing ammonia and immiscible oil. The density of the methanol was 0.792 g / cm 3 .

[0041] <Comparative Example 2> A sample of Comparative Example 2 was obtained in the same manner as in Example 1, except that the ammonia concentration was 0.01% by mass and immiscible oil was not mixed. The density of the fuel solution was 0.792 g / cm 3 . Needless to say, there was no oil film on the sample.

[0042] <Comparative Example 3> Ammonia (1 MPa, density 0.603 g / cm 3 ) was prepared, and a sample of Comparative Example 3 was obtained as it was. Needless to say, there was no oil film on the sample.

[0043] <Comparative Example 4> A sample of Comparative Example 4 was obtained in the same manner as in Example 1, except that the ammonia concentration was 30.0% by mass and immiscible oil was not mixed. The density of the fuel solution was 0.762 g / cm 3 . Needless to say, there was no oil film on the sample.

[0044] <Comparative Example 5> A sample of Comparative Example 5 was obtained in the same manner as in Example 1, except that 30% by mass of aqueous ammonia was mixed instead of ammonia and immiscible oil was not mixed. The composition of the aqueous fuel solution was 91.7% by mass of methanol, 2.5% by mass of ammonia, and 5.8% by mass of water. The density of the aqueous fuel solution was 0.801 g / cm 3 . Needless to say, there was no oil film on the sample.

[0045] <Comparative Example 6> A sample of Comparative Example 6 was obtained in the same manner as in Example 1, except that the ammonia concentration was 15.3% by mass and immiscible oil was not mixed. The density of the fuel solution was 0.779 g / cm 3 . Needless to say, there was no oil film on the sample.

[0046] Comparative Example 7 A sample of Comparative Example 7 was obtained in the same manner as in Example 1, except that the ammonia concentration was 8.7 mass% and no immiscible oil or fat was mixed. The density of the fuel solution was 0.781 g / cm 3 It goes without saying that there was no oil film on the sample.

[0047] "evaluation" Each sample was evaluated as follows.

[0048] Before mixing with the immiscible oil or fat, i.e., silicone oil, the flash point, minimum ignition energy (minimum ignition energy), flammable range (lower flammable limit, upper flammable limit), and vapor pressure were measured for each sample fuel solution.

[0049] The flash point was measured using a Seta type flash point tester in accordance with JIS K2265-2 of the Japanese Industrial Standards. The minimum ignition energy (minimum ignition energy) was measured using a 150 mL cylindrical explosion test apparatus. The flammability range (lower flammability limit, upper flammability limit) was measured using a spherical explosion test apparatus. The vapor pressure (298 K) was measured using a fully automatic chemical adsorption analyzer.

[0050] In addition, the weight and volumetric heat of combustion were calculated for the fuel solution of each sample before mixing with the immiscible oil or fat, i.e., silicone oil, and the onboard carbon dioxide (CO 2 The calculation method is as follows:

[0051] The combustion reaction of methanol is expressed as follows: CH 3 OH+3 / 2O 2 →CO 2 +2H 2 O (1)

[0052] The combustion reaction of ammonia is expressed as follows: NH 3 +3 / 4O2 →1 / 2N 2 +3 / 2H 2 O (2)

[0053] According to formula (1) and Non-Patent Document 1, the standard enthalpy change due to methanol combustion is -19.9 MJ / kg (LHV) and -638 kJ / mol (LHV). From this, the weighted heat of combustion is 19.9 MJ / kg (LHV, LHV: lower heating value) and 638 kJ / mol (LHV).

[0054] According to formula (2) and Non-Patent Document 1, the standard enthalpy change due to ammonia combustion is -18.6 MJ / kg (LHV) and -317 kJ / mol (LHV). From this, the weight-based heat of combustion is 18.6 MJ / kg (LHV) and 317 kJ / mol (LHV).

[0055] The weight heat of combustion of the fuel solution was calculated from these values ​​and the concentration (mass%) of ammonia in the fuel solution. The volumetric heat of combustion was also calculated using the density of the fuel solution.

[0056] In addition, the onboard CO2 emission rate is calculated from the weight heat of methanol combustion calculated from equation (1) and the amount of carbon dioxide released. 2 On the other hand, from equation (2), the onboard CO emissions from ammonia combustion were calculated. 2 The emissions were set to 0. From these, the onboard CO 2 The amount of emissions was calculated.

[0057] Based on the vapor pressure (298K) mentioned above, we determined whether the liquid could be stored under atmospheric pressure and whether it could be stored in a normal pressure container. A normal pressure container is equivalent to a "normal fuel tank."

[0058] Furthermore, after mixing the immiscible oil, i.e., silicone oil, it was visually confirmed that the silicone oil remained on the liquid surface of the fuel solution to form an oil film, and a fuel with an oil film was obtained. In addition, in the fuel with an oil film, the presence or absence of ammonia evaporation from the fuel solution was confirmed by visual observation and by the mass change of the fuel with an oil film.

[0059] The results are shown in Table 1.

[0060] [Table 1]

[0061] In all of the samples of Examples 1 to 5, no evaporation of ammonia was observed, and it was confirmed that storage in a normal pressure container was possible.

[0062] Furthermore, the flash point, minimum ignition energy, flammable range, and heat of combustion of the samples of Examples 1 to 5 are comparable to those of the methanol sample of Comparative Example 1, and the on-board carbon dioxide emissions are lower than those of methanol. Furthermore, the vapor pressure of ammonia is 1 atmosphere (0.1 MPa) or less. From this, it was confirmed that the samples of Examples 1 to 5 suppress the evaporation of ammonia, can be stored in a normal pressure container, and can safely replenish the fuel solution.

[0063] In contrast, in the sample of Comparative Example 2, the ammonia concentration is reduced to 0.01% by mass, so the carbon dioxide reduction effect is lost. In the sample of Comparative Example 3, the ammonia concentration is 100% by mass, so the flash point and minimum ignition energy are significantly higher than those of methanol, the flammable range is narrower, and the flammability is lower than that of methanol. In addition, the vapor pressure rises to 25 atm (2.5 MPa), making storage under atmospheric pressure difficult. Therefore, storage in a normal pressure container is difficult, and a pressure-resistant container is required. In addition, refueling is also difficult because of the high ammonia vapor pressure. In the sample of Comparative Example 4, the ammonia concentration is 30% by mass, so the flammability is improved compared to the case where all is ammonia, but since there is no mixture of immiscible oils and fats, ammonia evaporates. Furthermore, since the vapor pressure of ammonia is 4.8 atm (0.48 MPa), the evaporation of ammonia is significant. Therefore, storage and refueling under atmospheric pressure are difficult, and a pressure-resistant container is required. In the sample of Comparative Example 5, since there is no mixture of immiscible oils and fats and the ammonia evaporates, it is difficult to store and refuel under atmospheric pressure. In addition, since ammonia water is used instead of ammonia, the combustion heat is reduced.

[0064] From the above results, the effects of the oil film-attached fuel and immiscible oils and fats disclosed herein were confirmed. [Explanation of symbols]

[0065] 10. Tank 20 Main unit 30 Supply section 40 Lid 50 fuel solution 52 Liquid level 60 Immiscible fats and oils 70 Fuel with oil film

Claims

1. A fuel solution containing ammonia and methanol, and immiscible oil that is immiscible with the fuel solution are included, wherein the density of the immiscible oil is smaller than the density of the fuel solution, fuel with an oil film.

2. The fuel with an oil film according to Claim 1, wherein the immiscible oil is silicone oil.

3. The density of the immiscible oil is 0.770 g / cm ３ The fuel with an oil film according to claim 1 or 2, wherein the density is as follows.

4. The fuel with an oil film according to Claim 1 or 2, wherein the ammonia concentration in the fuel solution is 0.1 to 20.0% by mass.

5. Immiscible oil that is immiscible with a fuel solution containing ammonia and methanol, has a density smaller than that of the fuel solution, stays on the liquid surface of the fuel solution, and suppresses the evaporation of ammonia in the fuel solution.

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