Method for producing gasoline alternative fuel and gasoline alternative fuel

Abstract

To manufacture a gasoline substitute fuel having low carbon intensity.SOLUTION: A manufacturing method of a gasoline substitute fuel to manufacture a gasoline substitute fuel by blending FT light naphtha (base material) obtained by FT synthesis using renewable electric power and a bio-alcohol obtained from a biomass includes: determining a blending ratio of the bio-alcohol to the base material based on an octane number of the base material, a blending octane number of the bio-alcohol, and a predetermined objective octane number; determining a hydrogenation ratio for hydrogenation of olefins included in the base material to paraffins in a manner that an olefin content ratio of the gasoline substitute fuel becomes 10 vol% or under based on the determined blending ratio of the bio-alcohol and the olefin content ratio of the base material; hydrogenating the base material corresponding to the determined hydrogenation ratio; and blending the bio-alcohol with the base material which has been hydrogenated corresponding to the determined blending ratio of the bio-alcohol.SELECTED DRAWING: Figure 10

Description

[Technical field]

[0001] The present invention relates to a method for producing a gasoline alternative fuel using renewable energy, and to a gasoline alternative fuel. [Background technology]

[0002] Conventionally, fuel compositions as alternative fuels for gasoline have been known (see, for example, Patent Document 1). The fuel composition described in Patent Document 1 has a research octane number of 89.0 or more, and contains FT synthetic base material A (50≧A>0) volume % obtained from natural gas, petroleum liquefied gas, etc., ethers B (25≧B≧0) volume % having 4 to 8 carbon atoms, and alcohols C (15≧C≧0) volume % having 2 to 4 carbon atoms (B+C>0, A≧B+C). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2007-270091 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, since the fuel composition described in Patent Document 1 uses fossil fuels as raw materials, it is difficult to reduce the carbon emissions per unit energy (carbon intensity) of the final fuel produced. From the viewpoint of contributing to the mitigation or reduction of the impact of climate change, it is desirable to reduce the consumption of fossil fuels with high carbon intensity. [Means for solving the problem]

[0005] One aspect of the present invention is a method for producing an alternative fuel for gasoline by mixing FT light naphtha obtained by Fischer-Tropsch synthesis using renewable electricity with bioalcohol obtained from biomass. R .

[0006] The method for producing a gasoline alternative fuel includes: determining a blending ratio of bioalcohol to FT light naphtha based on an octane number of the FT light naphtha, a blending octane number of bioalcohol, and a predetermined target octane number; determining a hydrogenation ratio when hydrogenating olefins contained in the FT light naphtha to paraffin based on the determined blending ratio of bioalcohol and the olefin content ratio of the FT light naphtha so that the olefin content ratio of the gasoline alternative fuel is 10 vol% or less; hydrogenating the FT light naphtha according to the determined hydrogenation ratio; and blending the hydrogenated FT light naphtha with bioalcohol according to the determined blending ratio of bioalcohol. . Effect of the Invention

[0007] The present invention allows the production of a gasoline alternative fuel with low carbon intensity. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram for explaining renewable fuel produced using renewable energy. [Diagram 2] FIG. 2 is a diagram for explaining an octane improver. [Diagram 3] FIG. 2 is a diagram for explaining the carbon intensity of a fuel. [Figure 4] FIG. 2 is a diagram for explaining the difference in octane number improving effect depending on the composition of the base material. [Diagram 5] FIG. 2 is a diagram for explaining differences in carbon intensity due to fuel composition. [Figure 6] FIG. 2 is a diagram for explaining the relationship between the olefin content of the base material and the octane number improvement rate. [Figure 7] FIG. 2 is a diagram for explaining the blending octane number of alcohol. [Figure 8] FIG. 2 is a diagram for explaining the alcohol blend ratio required to obtain a gasoline alternative fuel. [Figure 9] FIG. 2 is a diagram for explaining the composition of a gasoline alternative fuel according to an embodiment of the present invention. [Figure 10] FIG. 2 illustrates a method for producing a gasoline alternative fuel according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention will be described with reference to Figs. 1 to 10. In the method for producing an alternative gasoline fuel according to the embodiment of the present invention, an alternative gasoline fuel with a low carbon intensity and an octane equivalent to that of gasoline is produced by reforming FT light naphtha with a low octane number obtained by Fischer-Tropsch synthesis using renewable electricity. In particular, an alternative gasoline fuel with an extremely low carbon intensity is produced by using FT light naphtha as a base material and mixing bioalcohol as an octane number improver.

[0010] The average temperature of the Earth is kept warm enough for living things by greenhouse gases in the atmosphere. Specifically, greenhouse gases absorb some of the heat radiated from the Earth's surface, which is warmed by sunlight, into space, and then re-radiate it back to the Earth's surface, thereby keeping the atmosphere warm. If the concentration of greenhouse gases in the atmosphere increases, the average temperature of the Earth will rise (global warming).

[0011] Carbon dioxide, which is one of the greenhouse gases that contributes most to global warming, has a concentration in the atmosphere that is determined by the balance between carbon fixed on the ground or underground as plants and fossil fuels, and carbon present in the atmosphere as carbon dioxide. For example, when carbon dioxide in the atmosphere is absorbed by plants through photosynthesis during growth, the concentration of carbon dioxide in the atmosphere decreases, and when carbon dioxide is released into the atmosphere through the combustion of fossil fuels, the concentration of carbon dioxide in the atmosphere increases. To prevent global warming, it is necessary to replace fossil fuels with renewable energy sources such as solar, wind, hydroelectric, geothermal, or biomass, and reduce carbon emissions.

[0012] Figure 1 is a diagram to explain renewable fuels (e-fuels) produced using such renewable energy. As shown in Figure 1, renewable electricity is generated by solar power generation, wind power generation, hydroelectric power generation, geothermal power generation, etc., and renewable hydrogen is produced by electrolysis of water using the renewable electricity. Furthermore, FT (Fischer-Tropsch) synthesis is performed using renewable hydrogen and carbon dioxide captured from factory exhaust gas, etc. to produce FT crude oil as e-fuel.

[0013] Due to the principle of the FT synthesis process, which is a polymerization reaction, FT crude oil contains a variety of components. Such FT crude oil can be fractionated according to the boiling point range and separated into FT diesel, jet fuel, and FT light naphtha as e-fuel. Of these, FT diesel can be used as fuel for diesel engines, and jet fuel can be used as fuel for jet engines as is.

[0014] FT light naphtha contains linear saturated hydrocarbons (normal paraffins) with a carbon number of about 6 to 10 as the main component. In addition, unsaturated hydrocarbons (olefins) and aromatic hydrocarbons (aromas) are contained as secondary components at a content rate according to the catalyst, reaction temperature, reaction time, etc. used in the FT synthesis process. Such FT light naphtha is suitable as a base material for gasoline alternative fuels because its vapor pressure characteristics (vaporization characteristics) comply with gasoline standards. However, FT light naphtha has an octane number (research method octane number) of about 60 to 70, which is lower than the gasoline standard (about 90), and if it is used as fuel for gasoline engines as it is, knocking may occur and the combustion performance of the engine may be impaired.

[0015] FIG. 2 is a diagram for explaining octane number improvers, and shows an example of the measurement results of the octane number of fuel obtained by mixing various octane number improvers with FT light naphtha (base material) with an octane number of 65. As shown in FIG. 2, when ethanol is used as an octane number improver, a desired octane number (for example, about 90) can be achieved at a lower mixing ratio than other octane number improvers (diisobutylene, cyclopentane, and toluene in FIG. 2). Furthermore, ethanol has a high octane number improvement rate (so-called blending octane number) in the range where the mixing ratio is low. In addition to ethanol, a similar tendency is observed with alcohols such as propanol and butanol.

[0016] FIG. 3 is a diagram for explaining the carbon intensity of fuels, showing an example of the carbon intensity when various fuels are used as vehicle fuel. As shown in FIG. 3, the carbon intensity of FT light naphtha, which is an e-fuel, is 1 g / mile, which is extremely lower than the carbon intensity of 220 g / mile of gasoline derived from fossil fuels. In addition, the carbon intensity of bioalcohol, for example, bioethanol, is 73 to 161 g / mile, which is lower than the carbon intensity of gasoline derived from fossil fuels, but higher than the carbon intensity of FT light naphtha, which is an e-fuel.

[0017] Bioalcohol blended fuels, in which bioalcohol such as bioethanol is mixed with gasoline, are widely used worldwide as vehicle fuels. In particular, bioethanol blended fuels are widely used and therefore have high availability. In this embodiment, a method for producing a gasoline alternative fuel is described, in which bioalcohol is mixed with and reformed using FT light naphtha, which is e-fuel, as a base material to produce a gasoline alternative fuel with an octane number equivalent to gasoline and an extremely low carbon intensity.

[0018] FIG. 4 is a diagram for explaining the difference in the octane number improvement effect depending on the composition of the base material, and as an example, shows the mixing ratio of ethanol required to achieve an octane number of 90 (calculation result by chemical reaction analysis). As shown in FIG. 4, the mixing ratio of ethanol required to achieve an octane number of 90 increases as the octane number of the base material decreases, regardless of the composition of the base material. In addition, a base material containing aroma as a secondary component requires a higher mixing ratio of ethanol to achieve an octane number of 90 than a base material containing only paraffin as the main component. Furthermore, a base material containing olefin as a secondary component requires a higher mixing ratio of ethanol to achieve an octane number of 90 than a base material containing aroma as a secondary component. A similar tendency is observed with propanol and butanol. This is because olefin and aroma inhibit the octane number improvement effect of alcohol such as ethanol.

[0019] FIG. 5 is a diagram for explaining the difference in carbon intensity depending on the fuel composition, and shows the carbon intensity of a fuel with an octane number of 90 as an example. As shown in FIG. 2 and FIG. 5, the carbon intensity of gasoline derived from fossil fuels is 220 g / mile. On the other hand, the carbon intensity of a fuel obtained by mixing 69 vol% of an e-fuel base material with an octane number of 60 containing 85 vol% paraffin and 15 vol% olefin with 31 vol% bioethanol (derived from corn) is 50.6 g / mile. Furthermore, the carbon intensity of a fuel obtained by mixing 79 vol% of an e-fuel base material with an octane number of 60 containing only paraffin with 21 vol% bioethanol (derived from corn) is 34.6 g / mile.

[0020] In this way, by reducing the content of olefins in the base material, which inhibit the octane number improving effect of alcohols such as ethanol, the blending ratio of alcohol required to achieve an octane number of 90 can be reduced, thereby reducing the carbon strength of the resulting fuel. In the example of Figure 5, by reducing the olefin content of the base material from 15 vol% to 0 vol%, the carbon strength of the resulting fuel is reduced by approximately 32%, from 50.6 g / mile to 34.6 g / mile.

[0021] Olefins can be converted to paraffins (normal paraffins) by hydrogenation (cracking reaction). Hydrogenation of olefins to paraffins is carried out at high temperatures (approximately 200 to 430°C) and high pressures (70 to 210 kg / cm) in the presence of a catalyst in which active metals such as tungsten, iron, or nickel are supported on an acidic support such as silica or alumina. 2 The reaction proceeds in a hydrogen stream at a temperature of about 1000° C. This reaction can be carried out in a fixed-bed or fluidized-bed reactor. Renewable hydrogen (Fig. 1), obtained by electrolysis of water using renewable electricity, can be used for the hydrogenation of olefins to paraffins, but additional energy input is required.

[0022] 6 is a diagram for explaining the relationship between the olefin content of the base material and the octane number improvement rate, and as an example, shows the octane number improvement rate (calculated by chemical reaction analysis) when 1 vol% of ethanol is mixed into base materials with different olefin content rates. More specifically, the octane number improvement rate ((octane number after mixing with ethanol) / (octane number of base material)) when ethanol is mixed into a base material with an olefin content rate of 0 vol% is set to "1", and the relative octane number improvement rate when the olefin content rate of the base material is changed is shown.

[0023] As shown in FIG. 6, the higher the olefin content of the base material, the lower the octane number improvement rate due to the blending of ethanol, and the greater the rate of decrease in the octane number improvement rate. The rate of decrease in the octane number improvement rate increases as the olefin content of the base material increases, with an inflection point at around 10 vol%. A similar tendency is observed with propanol and butanol. This tendency can also be confirmed by actual experimental results. Considering the effect of improving the octane number by blending alcohol such as ethanol and the additional energy input required for hydrogenation, it is preferable to hydrogenate olefins to paraffins until the olefin content is at least 10 vol% or less.

[0024] In addition, olefins have low oxidation stability, and the OICA (International Organization of Automobiles) gasoline standard (category 3 to 6) stipulates that the olefin content in vehicle fuel must be 10 vol% or less. Therefore, from the viewpoint of the oxidation stability of the fuel, it is preferable to carry out the hydrogenation of olefins to paraffins until the olefin content is at least 10 vol% or less.

[0025] Normal paraffin, which is also the main component of the base material FT light naphtha, precipitates heavy components (paraffin wax) at low temperatures (approximately 5°C or less). Therefore, from the viewpoint of low-temperature performance of the fuel, it is preferable to convert a part of normal paraffin to isoparaffin, which is difficult to crystallize, by an isomerization reaction. When normal paraffin is isomerized to isoparaffin, the octane number of the entire base material is improved according to the isomerization ratio. The isomerization ratio from normal paraffin to isoparaffin is determined by the equipment specifications, the amount of energy that can be input, costs, etc.

[0026] FIG. 7 is a diagram for explaining the blending octane number of alcohol. FIG. 7 shows, as an example, the blending octane number based on the calculation result by chemical reaction calculation and the actual measurement result when ethanol is mixed with a base material having an olefin content ratio of 10 vol% with a different octane number. As shown in FIG. 7, in the low octane number range of the base material of about 50 to 100, the lower the octane number of the base material, the higher the octane number when ethanol is mixed. A similar tendency is seen with propanol and butanol.

[0027] FIG. 8 is a diagram for explaining the blending ratio of alcohol required to obtain a gasoline alternative fuel, and shows, as an example, the blending ratio of ethanol required to achieve an octane number of 90. In FIG. 8, the calculation result of the blending ratio b of ethanol calculated by the following formula (i) based on the blending octane number in FIG. 7 is shown by a black circle, and the experimental result is shown by a white circle. In formula (i), (1-b) represents the blending ratio of the base material. As shown in FIG. 8, the blending ratio of ethanol required to achieve an octane number of 90 roughly coincides with the predicted value based on the blending octane number in FIG. 7 (solid line in FIG. 8). (Base material octane number) x (Base material blend ratio) + (Blending octane number) x (ethanol blend ratio) = (desired octane number) (Base octane number)(1-b)+(Blending octane number)b=90 (i)

[0028] Since the octane number of the base material (FT light naphtha) is about 60 to 70, the blending ratio of ethanol is 30 vol% or less, as shown in Figure 8. Therefore, the content of the base material (FT light naphtha) in the final gasoline alternative fuel obtained by blending ethanol with the base material is 70 vol% or more. The same blending ratio (alcohol 30 vol% or less, base material (FT light naphtha) 70 vol% or more) is obtained when alcohols such as propanol and butanol are mixed in addition to ethanol.

[0029] FIG. 9 is a diagram for explaining the composition of a gasoline alternative fuel according to an embodiment of the present invention. As shown in FIG. 9, FT light naphtha (base material) contains ovol% of olefins together with normal paraffins as the main component. The olefin content ratio ovol% of the base material can be measured, for example, by analyzing the actual base material. After hydrogenation, a portion of the olefins ((100-α)vol% of olefins) is hydrogenated to normal paraffins, and the base material contains oαvol% of olefins. After further isomerization, a portion of the normal paraffins (ivol% of the entire base material) is isomerized to isoparaffins, and the base material contains ivol% of isoparaffins.

[0030] The final gasoline alternative fuel with a desired octane number (e.g., octane number 90) contains b vol% bioalcohol (e.g., bioethanol) relative to 100 vol% of the base material after pretreatment (hydrogenation, isomerization). The mixing ratio b of the bioalcohol to the base material can be calculated based on predetermined characteristics such as those shown in FIG. 8. The octane number of the base material can be estimated by additive calculation based on the isomerization ratio, etc., which is estimated according to the FT synthesis process or determined according to the composition of the base material (carbon number distribution and olefin content ratio of normal paraffin) measured by analysis, the equipment specifications, etc.

[0031] The olefin content of the final gasoline alternative fuel is (oα / (100+b)). From the viewpoint of the octane number improvement effect by mixing bioalcohol and the oxidation stability of the fuel, it is preferable to determine the hydrogenation ratio α of the base material so as to satisfy the following formula (ii). Taking into consideration the balance with the input energy required for hydrogenating the base material and the decrease in octane number due to excessive hydrogenation, it is preferable to determine the hydrogenation ratio α so that, for example, both sides of the following formula (ii) are equal. 100oα / (100+b)≦10 (ii)

[0032] FIG. 10 is a diagram illustrating a method for producing a gasoline alternative fuel according to an embodiment of the present invention. As shown in FIG. 10, first, the olefin content ratio o of the base material is measured (step S1). Next, the octane number of the base material is calculated based on the olefin content ratio o of the base material measured in step S1 and the isomerization ratio i of the base material determined according to the equipment specifications, etc. (step S2). Next, based on the predetermined characteristics as shown in FIG. 8, an appropriate bioalcohol blending ratio b according to the octane number of the base material calculated in step S2 is calculated (step S3). More specifically, the octane number of the base material calculated in step S2, the blending octane number of the bioalcohol corresponding to the octane number of the base material as shown in FIG. 7, and the octane number to be achieved (for example, 90) are substituted into formula (i). Then, the equation of formula (i) is solved for the bioalcohol blending ratio b to calculate the bioalcohol blending ratio b and the base material blending ratio (1-b). (Base material octane number) x (Base material blend ratio) + (Blending octane number) x (bioalcohol blend ratio) = (desired octane number) (Base octane number)(1-b)+(Blending octane number)b=90 (i)

[0033] Next, based on the mixing ratio b of the bioalcohol calculated in step S3 and the olefin content ratio o of the base material measured in step S1, the hydrogenation ratio α in the base material is calculated so that the olefin content ratio of the gasoline alternative fuel is 10 vol% or less (step S4). Next, the base material containing olefins is hydrogenated according to the hydrogenation ratio α calculated in step S4 (step S5). Next, the base material hydrogenated in step S5 is further isomerized according to a predetermined isomerization ratio i (step S6). Next, the bioalcohol is mixed with the base material isomerized in step S6 at the mixing ratio b calculated in step S3 (step S7). This completes the gasoline alternative fuel.

[0034] According to this embodiment, the following advantageous effects can be obtained. (1) A method for producing a gasoline alternative fuel by mixing FT light naphtha (base material) obtained by FT synthesis using renewable electricity with bioalcohol obtained from biomass includes determining a mixing ratio b of bioalcohol to the base material based on the octane number of the base material, the blending octane number of the bioalcohol, and a predetermined target octane number (steps S1 to S3), determining a hydrogenation ratio α when hydrogenating olefins contained in the base material to paraffin based on the determined mixing ratio b of bioalcohol and the olefin content ratio o of the base material so that the olefin content ratio (oα / (100+b)) of the gasoline alternative fuel is 10 vol% or less (step S4), hydrogenating the base material according to the determined hydrogenation ratio α (step S5), and mixing bioalcohol with the hydrogenated base material according to the determined mixing ratio b of bioalcohol (step S7) (FIG. 10).

[0035] In this way, by using FT light naphtha, which is an e-fuel, as the base material and mixing it with bioalcohol in an appropriate ratio, it is possible to produce a gasoline alternative fuel with an octane number equivalent to gasoline and extremely low carbon intensity. In addition, by hydrogenating the base material and performing pre-treatment to reduce the content of olefins that inhibit the effect of improving the octane number, it is possible to reduce the mixing ratio of bioalcohol required to achieve an octane number equivalent to gasoline, and further reduce the carbon intensity of the fuel (Figures 5 and 6).

[0036] (2) The method for producing a gasoline alternative fuel further includes isomerizing normal paraffins contained in the hydrogenated base material to isoparaffins (step S6) (FIG. 10). This improves the low-temperature performance of the fuel. In addition, isomerizing normal paraffins to isoparaffins improves the octane number, and the mixing ratio of bioalcohol required to achieve an octane number equivalent to that of gasoline is further reduced, thereby further reducing the carbon intensity of the fuel.

[0037] (3) Bioalcohol is any one of bioethanol, biopropanol, and biobutanol. For example, bioethanol, which is widely used and has high availability, can be used as an octane enhancer.

[0038] (4) The gasoline alternative fuel contains FT light naphtha (base material) derived from renewable energy and bioalcohol (Figures 1 and 9). The olefin content of the gasoline alternative fuel is 10 vol% or less. The content of bioalcohol relative to the base material is determined based on the octane number of the base material, the blending octane number of the bioalcohol, and a predetermined target octane number. By setting the olefin content to 10 vol% or less, the content of bioalcohol is minimized, making it possible to realize a gasoline alternative fuel with extremely low carbon intensity. Such a fuel also complies with gasoline standards for oxidation stability.

[0039] In the above embodiment, an example of performing FT synthesis using renewable hydrogen and carbon dioxide recovered from factory exhaust gas etc. has been described in Fig. 1 etc., but FT synthesis using renewable electricity is not limited to this. For example, biomass, natural gas, coal etc. may be used.

[0040] In the above embodiment, an example of obtaining an FT light naphtha having a carbon number of about 6 to 10 from FT crude oil by fractional distillation has been described in FIG. 1 and the like, but the FT light naphtha obtained by FT synthesis is not limited to this. For example, the conditions of the FT synthesis process itself may be adapted so that an FT light naphtha having a carbon number of about 6 to 10 is obtained. In this case, the fractional distillation step is not required.

[0041] In the above embodiment, an example in which the base material is isomerized and then mixed with bioalcohol has been described with reference to FIG. 10 and the like, but the method for producing a gasoline alternative fuel is not limited to this. For example, if the low temperature performance of the fuel is not a consideration, the isomerization step is not necessary.

[0042] The above description is merely an example, and the present invention is not limited to the above-mentioned embodiment and modifications, as long as the features of the present invention are not impaired. The above-mentioned embodiment and one or more modifications can be arbitrarily combined, and modifications can be combined with each other.

Claims

1. A method for producing an alternative gasoline fuel by mixing FT light naphtha obtained by Fischer-Tropsch synthesis using renewable electricity and bioalcohol obtained from biomass, Based on the octane number of the FT light naphtha, the blending octane number of the bioalcohol, and a predetermined target octane number, a mixing ratio of the bioalcohol to the FT light naphtha is determined; Based on the determined mixing ratio of the bioalcohol and the olefin content ratio of the FT light naphtha, a hydrogenation ratio is determined when hydrogenating the olefins contained in the FT light naphtha into paraffins so that the olefin content ratio of the gasoline alternative fuel is 10 vol% or less; Hydrogenating the FT light naphtha in accordance with the determined hydrogenation ratio; A method for producing a gasoline alternative fuel, comprising mixing the hydrogenated FT light naphtha with the bioalcohol in accordance with the determined mixing ratio of the bioalcohol.

2. 2. The method for producing a gasoline alternative fuel according to claim 1, A method for producing a gasoline alternative fuel, further comprising isomerizing normal paraffins contained in the hydrogenated FT light naphtha to isoparaffins.

3. 3. The method for producing a gasoline alternative fuel according to claim 1 or 2, The method for producing a gasoline alternative fuel, wherein the bioalcohol is any one of bioethanol, biopropanol, and biobutanol.

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