Hydrocarbon generation method and hydrocarbon generation device

Abstract

The present invention addresses the problem of providing technology relating to a hydrocarbon generation method and a hydrocarbon generation device whereby it is possible to reduce the facilities and equipment constituting a plant and achieve easier on-site generation of a hydrocarbon having a specific carbon number.　In order to solve the abovementioned problem, the present invention provides: a hydrocarbon generation method including an FT synthesis reaction step in which a raw material gas is supplied into a reaction vessel including a reaction catalyst and a Fischer-Tropsch synthesis reaction is performed, and a saturated hydrocarbon recovery step in which a saturated hydrocarbon having 8 to 16 carbon atoms is selectively recovered, wherein The FT synthesis reaction step is performed under conditions in which the value of the chain growth probability (α) in the Fischer-Tropsch synthesis reaction is 0.65 to 0.85; and a hydrocarbon generation device based on the hydrocarbon generation method.　The present invention makes it possible to easily generate a saturated hydrocarbon that is useful as a SAF.

Description

Hydrocarbon production method and hydrocarbon production device

[0001] The present invention relates to a hydrocarbon production method and hydrocarbon production apparatus using a Fischer-Tropsch synthesis reaction (hereinafter also referred to as "FT synthesis reaction"). More specifically, the present invention relates to a hydrocarbon production method and hydrocarbon production apparatus that use the FT synthesis reaction to obtain saturated hydrocarbons having a specific carbon number.

[0002] The FT synthesis reaction is a reaction in which a mixed gas of carbon monoxide and hydrogen is reacted in the presence of a catalyst to produce a hydrocarbon mixture.

[0003] Patent Document 1 describes a synthesis gas production method that can reduce the operating costs in the upgrading reaction step or make the equipment more compact in a process for producing liquid hydrocarbons from natural gas, as well as a synthesis gas production method that can increase the raw material consumption rate by re-introducing purge gas from the hydrogen separation step into the process and reusing it as a raw material.

[0004] JP 2009-242154 A

[0005] As described in Patent Document 1, conventional FT synthesis reactions produce hydrocarbons with a wide range of carbon numbers, which poses many problems in fields where hydrocarbons with a specific carbon number are required depending on the application.

[0006] Among the hydrocarbons obtained by the FT synthesis reaction, saturated hydrocarbons with carbon numbers of 8 to 16, in particular, have been attracting attention for use as jet fuel known as SAF (Sustainable Aviation Fuel) from the perspective of reducing carbon dioxide emissions. However, obtaining jet fuel using conventional technologies required the following steps: (1) a separation process between liquid hydrocarbons and wax components; (2) distillation of the liquid hydrocarbons; and (3) upgrading of the wax components (hydrocracking and hydrotreating). Therefore, in addition to the FT synthesis reactor, additional equipment such as a distillation unit, hydrocracking unit, and hydrogenation unit was required. Under these circumstances, in order to advance technological development related to SAF, which is expected to contribute to the realization of a carbon-neutral society, it is necessary to perform fuel synthesis alongside carbon dioxide capture and hydrogen electrolysis equipment. Therefore, there is an urgent need to develop new technologies that can eliminate or simplify the additional equipment. In other words, there is a demand for a technology that can reduce the facilities and equipment that make up a plant in order to produce SAF on-site and obtain SAF more easily.

[0007] An object of the present invention is to provide technology relating to a hydrocarbon production method and a hydrocarbon production apparatus that can reduce the facilities and equipment that make up a plant and more easily produce hydrocarbons having a specific carbon number on-site.

[0008] As a result of extensive research into the above-mentioned problems, the present inventors have found that useful saturated hydrocarbons that can be used in SAF and the like can be easily obtained by carrying out the Fischer-Tropsch synthesis reaction under conditions in which the value of the chain propagation probability (α) falls within a specific range and selectively extracting saturated hydrocarbons having a specific carbon number (8 to 16 carbon atoms), and have thus completed the present invention.

[0009] The hydrocarbon production method of the present invention, which solves the above-mentioned problems, includes an FT synthesis reaction step of supplying a feedstock gas into a reaction vessel containing a reaction catalyst and carrying out a Fischer-Tropsch synthesis reaction, and a saturated hydrocarbon recovery step of selectively recovering saturated hydrocarbons having a carbon number of 16 or less, wherein the FT synthesis reaction step is carried out under conditions in which the value of the chain propagation probability (α) in the Fischer-Tropsch synthesis reaction is 0.85 or less. According to the present invention, by allowing the FT synthesis reaction to proceed so as to satisfy a specific chain propagation probability value, it is possible to select to a certain extent the carbon number of the resulting hydrocarbons (saturated hydrocarbons), and further by selectively recovering saturated hydrocarbons having a specific carbon number, it is possible to simply produce saturated hydrocarbons useful as SAF.

[0010] In one embodiment of the saturated hydrocarbon production method of the present invention, the saturated hydrocarbon recovery step includes a reflux step of refluxing the saturated hydrocarbons obtained in the FT synthesis reaction step, and the reflux step is carried out at a temperature of 110° C. or higher and 230° C. or lower. According to the present invention, a jet fuel (SAF) fraction having a carbon number of about 8 to 16 can be selectively obtained.

[0011] In one embodiment of the method for producing saturated hydrocarbons of the present invention, the FT synthesis reaction step is carried out at a reaction temperature of 200° C. or higher and 270° C. or lower. ２ The conversion rate is increased, and productivity can be improved.

[0012] In one embodiment of the method for producing saturated hydrocarbons of the present invention, the FT synthesis reaction step is carried out at a reaction pressure of 0.5 MPa G or more and 3 MPa G or less. According to the present invention, chain growth can be promoted.

[0013] In one embodiment of the method for producing saturated hydrocarbons according to the present invention, the reaction catalyst used in the FT synthesis reaction step contains at least one element selected from the group consisting of yttrium, cerium, lanthanum, praseodymium, neodymium, holmium, sodium, potassium, rubidium, cesium, beryllium, magnesium, calcium, strontium, barium, and copper. According to the present invention, it is possible to increase the amounts of carbon monoxide and carbon dioxide adsorbed on the catalyst surface and also to increase the number of reaction active sites.

[0014] In one embodiment of the method for producing saturated hydrocarbons according to the present invention, the reaction catalyst contains at least one selected from the group consisting of cobalt, ruthenium, and iron. According to the present invention, a fraction of saturated hydrocarbons (fraction equivalent to SAF) having a carbon number sufficient for use in diesel, jet fuel (SAF), kerosene, etc. can be efficiently obtained.

[0015] In one embodiment of the method for producing saturated hydrocarbons of this other invention, the value of the chain growth probability (α) is 0.72 to 0.78. According to the present invention, the production efficiency of the SAF-equivalent fraction can be increased.

[0016] Furthermore, the present invention provides an apparatus for producing saturated hydrocarbons that solves the above-mentioned problems, and is characterized in that it comprises an FT synthesis reaction section in which a feedstock gas is supplied into a reaction vessel containing a reaction catalyst and a Fischer-Tropsch synthesis reaction is carried out, and a saturated hydrocarbon recovery section in which saturated hydrocarbons having a carbon number of 16 or less are selectively recovered, and the FT synthesis reaction section is operated under conditions in which the value of the chain propagation probability (α) in the Fischer-Tropsch synthesis reaction is 0.85 or less. According to the present invention, by allowing the FT synthesis reaction to proceed so as to satisfy a specific chain propagation probability value, it is possible to select to a certain extent the carbon number of the resulting hydrocarbons (saturated hydrocarbons), and further by selectively recovering saturated hydrocarbons having a specific carbon number, it is possible to simply produce saturated hydrocarbons that are useful as SAF.

[0017] In one embodiment of the saturated hydrocarbon production apparatus of the present invention, the saturated hydrocarbon recovery section includes a reflux section for refluxing the saturated hydrocarbons obtained in the FT synthesis reaction section, and the reflux section is maintained at a temperature of 110° C. or higher and 230° C. or lower. According to the present invention, a jet fuel (SAF) fraction having a carbon number of about 8 to 16 can be selectively obtained.

[0018] According to the present invention, it is possible to provide a technology relating to a hydrocarbon production method and a hydrocarbon production apparatus that can reduce the facilities and equipment that make up a plant and more easily produce hydrocarbons having a specific carbon number on-site.

[0019] Fig. 1 is a schematic diagram illustrating a catalyst surface reaction in an FT synthesis reaction. Fig. 2 is a schematic diagram illustrating the chain propagation probability and the distribution of hydrocarbon (crude product) composition obtained by an FT synthesis reaction. Fig. 3 is a graph of product distribution in an FT synthesis reaction when the chain propagation probability is (α=0.9). Fig. 4 is a graph of product distribution in an FT synthesis reaction when the chain propagation probability is (α=0.75). Fig. 5 is a schematic explanatory diagram of a hydrocarbon production apparatus in an embodiment of the present invention.

[0020] Hereinafter, embodiments of the hydrocarbon production method and hydrocarbon production device according to the present invention will be described in detail with reference to the drawings. Note that the hydrocarbon production device described as an embodiment is merely an example for explaining the hydrocarbon production device according to the present invention, and is not limited thereto. Furthermore, part of the description of the hydrocarbon production method according to this embodiment will be replaced with the description of the configuration and operation of the hydrocarbon production device below.

[0021] First, an outline of the FT synthesis reaction will be explained with reference to FIG. 1. The FT synthesis reaction is a process in which synthesis gas (carbon monoxide (CO) and hydrogen (H ２ ) is contacted with a catalyst to form a methylene group (—CH ２ -) and methane (C １ ) ~ Wax (C ３０＋ ) to produce hydrocarbons with a wide range of carbon numbers.

[0022] In this case, the types of hydrocarbons produced follow the ASF distribution based on the Anderson-Schulz-Flory (hereinafter referred to as "ASF") law. It is known that the composition of the hydrocarbons produced correlates with the value of the chain growth probability (α) in the FT synthesis reaction as shown in Equation 2. Here, W ｎ is the weight fraction of hydrocarbon products consisting of n carbon atoms in all hydrocarbons, and α is the chain growth probability.

[0023] The chain propagation probability (α) is expressed by the chain propagation rate (kp), which is the rate at which carbon chains increase in the FT synthesis reaction shown in FIG. 1, and the hydrolysis desorption rate (kd), which is the rate at which hydrocarbons on the catalyst surface are hydrogenated and desorbed (α=kp / (kp+kd)), and varies depending on the reaction conditions (temperature, pressure) of the FT synthesis reaction and the type of catalyst used.

[0024] FIG. 2 shows the relationship between the chain propagation probability (α) and the composition of hydrocarbons (crude product composition) produced by the FT synthesis reaction. As shown in FIG. 2, it can be seen that hydrocarbons produced by the FT synthesis reaction contain multiple hydrocarbon compositions regardless of the value of the chain propagation probability (α). Therefore, it is difficult to obtain only hydrocarbons with a specific composition or only hydrocarbons suitable for a specific application using a conventional FT synthesis reaction. For example, when attempting to produce jet fuel, the wax component is separated from the product (step 1) and the wax component is upgraded (hydrocracking and hydrotreating) (step 2). The liquid hydrocarbons obtained in step 1 and the hydrocracked and hydrotreated liquid hydrocarbons obtained in step 2 are distilled to obtain hydrocarbons with a carbon number of 9 to 15 (C ９ ~C １５ ) jet fuel fraction (Step 3) was obtained.

[0025] On the other hand, in the hydrocarbon production method of this embodiment, the Fischer-Tropsch synthesis reaction is carried out under conditions in which the value of the chain propagation probability (α) falls within a specific range, and saturated hydrocarbons having 8 to 16 carbon atoms are selectively recovered, thereby easily obtaining useful saturated hydrocarbons that can be used in SAF and the like. More specifically, the hydrocarbon production method of this embodiment comprises the following steps. That is, the hydrocarbon production method of this embodiment includes an FT synthesis reaction step in which a feed gas is supplied into a reaction vessel containing a reaction catalyst and the Fischer-Tropsch synthesis reaction is carried out, and a saturated hydrocarbon recovery step in which saturated hydrocarbons having 8 to 16 carbon atoms are selectively recovered. The FT synthesis reaction step is carried out under conditions in which the value of the chain propagation probability (α) in the Fischer-Tropsch synthesis reaction falls within a range of 0.65 to 0.85.

[0026] Each step will be described below: The hydrocarbon production method of this embodiment includes an FT synthesis reaction step in which a raw material gas is supplied into a reaction vessel containing a reaction catalyst and a Fischer-Tropsch synthesis reaction is carried out.

[0027] The raw material gas is a raw material for producing hydrocarbons by the FT synthesis reaction. As described above, in a typical FT synthesis reaction, carbon monoxide (CO) and hydrogen (H ２ ), but in this embodiment, carbon dioxide (CO ２ ) may be contained.

[0028] Regarding the raw material gas, the rate of the FT synthesis reaction depends on the hydrogen partial pressure, so a certain amount of H ２A partial pressure is required, and the ratio (molar ratio) of hydrogen to the total (carbon monoxide + carbon dioxide) pressure in the feed gas is suitably 0.6 to 2.7, preferably 0.8 to 2.5, and more preferably 1 to 2.3. The ratio of carbon monoxide to carbon dioxide can be varied depending on the purpose. For the purpose of carbon recycling, the ratio of carbon dioxide is increased, and for increasing the conversion rate to hydrocarbons, the ratio of carbon monoxide is increased. In this embodiment, carbon dioxide may be 100%, and carbon monoxide may not be used. When both are used in combination, the ratio of carbon dioxide to carbon monoxide is not particularly limited, but the ratio of carbon dioxide to the total amount of carbon monoxide and carbon dioxide must be 1% by volume or more, preferably 10% by volume or more, more preferably 30% by volume or more, and even more preferably 40% by volume or more. Furthermore, as other components, substances other than the above-mentioned hydrogen, carbon monoxide, and carbon dioxide may be mixed into the feed gas as long as they do not interfere with the FT synthesis reaction.

[0029] The reaction vessel into which the raw material gas is introduced and the catalyst placed in the reaction vessel may be any of those that can cause the FT synthesis reaction step in this embodiment to proceed so that the value of the chain growth probability (α) satisfies a specific range, and specific examples will be given in the description of the hydrocarbon production apparatus that produces hydrocarbons based on the hydrocarbon production method of this embodiment (the hydrocarbon production apparatus of this embodiment). Furthermore, the conditions (reaction temperature, reaction pressure) under which the FT synthesis reaction in the FT synthesis reaction step proceeds may also be any of those that can cause the chain growth probability (α) to proceed so that the value of the chain growth probability (α) satisfies a specific range, and specific examples will be given later in conjunction with the description of the hydrocarbon production apparatus of this embodiment.

[0030] Here, the technical significance of carrying out the FT synthesis reaction under conditions in which the value of the chain growth probability (α) is 0.65 to 0.85 in the FT synthesis reaction step in the hydrocarbon production method of this embodiment will be described. As shown in FIG. 1 , the FT synthesis reaction is a type of polymerization reaction, and it is generally difficult to keep the degree of polymerization (n number) constant. １ ~C １００＋As mentioned above, the carbon number distribution of the produced hydrocarbons follows the ASF distribution law and can be expressed by the chain propagation probability (α) in this distribution law, and it is known that the value of the chain propagation probability (α) for industrial catalysts is approximately 0.85 to 0.95.

[0031] Fig. 3 shows the product distribution when the FT synthesis reaction is carried out under the condition of α = 0.9, and is a comparative example for the hydrocarbon production method of this embodiment. A silica-supported cobalt catalyst (Na-Co / SiO ２ The catalyst to dispersion medium ratio was 25 (w / w)%. The reaction temperature was 220°C, and the pressure was 950 kPa, G (9.5 kg / cm ２ , G), and the volume of the mixed gas (H ２ / CO ratio 1 / 2 (0.5)) and the ventilation volume (volume (vg)) per hour was set to 500 to 750 (vg / vc·h －１ ) and performed the FT reaction. The once-through conversion was 10-12%, and the chain propagation probability (α) was 0.9. In Figure 3, the horizontal axis represents the carbon number, and the vertical axis represents the hydrocarbon weight distribution. As shown in Figure 3, when the FT synthesis reaction is performed with α = 0.9, products with a wide range of carbon numbers are obtained. However, in this case, various separation processes (distillation, upgrading by hydrocracking and hydrotreating, etc.) are required for the products to obtain hydrocarbons with a specific carbon number, such as SAF, which results in a large number of ancillary facilities and units constituting the plant.

[0032] On the other hand, Figure 4 shows the product distribution when the FT synthesis reaction is carried out under the condition of α = 0.75, and is one example of the hydrocarbon production method of this embodiment. A silica-supported cobalt catalyst (Ce-Co / SiO ２ The catalyst to dispersion medium ratio was 3 (w / w)%. The reaction temperature was 230°C, the pressure was 600 kPa, and the G (6 kg / cm ２, G), and the ratio of the mixed gas (H ２ / CO ratio 2 / 1 (2.0)) per hour, the ventilation volume (vg) is 1,100 to 1,500 (vg / vc·h －１ ) and performed the FT reaction. The one-pass conversion rate at this time was 50-58%, and the chain propagation probability (α) was 0.75. As in FIG. 3, the horizontal axis of FIG. 4 represents the carbon number, and the vertical axis represents the hydrocarbon weight distribution. It goes without saying that the above-mentioned conditions are merely an example and are not limited to these conditions. As shown in FIG. 4, when the FT synthesis reaction is performed with α = 0.75, the weight distribution of the product decreases as the carbon number increases. In other words, it is possible to suppress the production of hydrocarbons with a carbon number of 17 or more, particularly hydrocarbons with a carbon number of 22 or more, which have a carbon number greater than the carbon number (8-16) associated with saturated hydrocarbons useful as SAF.

[0033] 3 and 4 show that, depending on the value of the chain propagation probability (α), it is possible to make the carbon number of the product produced in the FT synthesis reaction unevenly distributed to a certain extent within a specific range. In the FT synthesis reaction step of this embodiment, the value of the chain propagation probability (α) suitable for obtaining saturated hydrocarbons having a carbon number (8 to 16 carbon atoms) particularly useful as SAF (hereinafter referred to as "SAF-equivalent fraction") is preferably 0.65 or more and 0.85 or less, more preferably 0.70 or more and 0.80 or less, and most preferably 0.72 or more and 0.78 or less. Outside this range, the production efficiency of the SAF-equivalent fraction decreases.

[0034] In the hydrocarbon production method of this embodiment, by setting the value of the chain growth probability (α) in the FT synthesis reaction step within a specific range (0.65 to 0.85), upgrading by hydrocracking and hydrotreating, which was previously required to obtain hydrocarbons having a specific carbon number such as SAF, becomes unnecessary, and plant space can be saved by reducing the amount of ancillary equipment that makes up the plant.

[0035] The hydrocarbon production method of this embodiment also includes a saturated hydrocarbon recovery step in which saturated hydrocarbons having 8 to 16 carbon atoms are selectively recovered from the hydrocarbons obtained in the above-described FT synthesis reaction step. At this time, the hydrocarbons introduced into the saturated hydrocarbon recovery step are mainly those having a carbon number of 20 or less. Therefore, the saturated hydrocarbon recovery step may be any step that can effectively separate and recover saturated hydrocarbons having 8 to 16 carbon atoms from this step.

[0036] An example of the saturated hydrocarbon recovery step in this embodiment includes a reflux step in which the saturated hydrocarbons obtained in the FT synthesis reaction step are refluxed. In the reflux step of this embodiment, the temperature range suitable for obtaining the SAF-equivalent fraction is preferably 110°C or higher and 230°C or lower, more preferably 150°C or higher and 230°C or lower, and most preferably 170°C or higher and 220°C or lower. Below this temperature, naphtha, which is lighter than the SAF-equivalent fraction, is recovered as the main component. Furthermore, above this temperature, the difference between the total hydrocarbons (fraction obtained in the FT synthesis reaction step) introduced into the saturated hydrocarbon recovery step is small.

[0037] [Hydrocarbon Production Apparatus] The hydrocarbon production apparatus in this embodiment is an apparatus for producing hydrocarbons based on the hydrocarbon production method described above, and includes an FT synthesis reaction section in which a feed gas is supplied into a reaction vessel containing a reaction catalyst to perform an FT synthesis reaction, and a saturated hydrocarbon recovery section in which saturated hydrocarbons having 8 to 16 carbon atoms are selectively recovered. The saturated hydrocarbon recovery section may include a reflux section in which the saturated hydrocarbons obtained in the FT synthesis reaction section are refluxed. More specifically, the hydrocarbon production apparatus in this embodiment may include a reflux unit, which corresponds to the reflux section in the saturated hydrocarbon recovery section, installed downstream of the upflow in which components including unreacted gas are vented upward from the FT synthesis reaction section at the FT reaction temperature, and a cooling unit installed downstream of that unit, and a fraction collector installed in series downstream of that unit. As will be described in more detail below, the reflux unit may be maintained at a predetermined temperature and may be filled with a plate-like structure and a hollow ring.

[0038] 5 is a schematic diagram of a hydrocarbon production system 100 according to an embodiment of the present invention. Referring to FIG. 5, the hydrocarbon production system 100 according to this embodiment will be described.

[0039] 5, the hydrocarbon production system 100 includes an FT reactor 10 as an FT synthesis reaction section, a reflux unit 20 as a saturated hydrocarbon recovery section, a cooling unit 30, and a fraction collector 40. Each component of the hydrocarbon production system 100 in this embodiment and its operation (action) will be described below.

[0040] <FT synthesis reaction section> The FT synthesis reaction section is for carrying out the above-described FT synthesis reaction step, and supplies a raw material gas into a reaction vessel (FT reactor 10 in this embodiment) containing a reaction catalyst to carry out the FT synthesis reaction.

[0041] <Reaction Type Related to FT Reactor> The most preferred type of FT reactor 10 related to the FT synthesis reaction section in this embodiment is a slurry bubble column reactor (SBCR) 10. This is for capturing the hydrocarbon vapor containing the SAF fraction rising from the top of the reactor. When the hydrocarbon vapor containing the SAF fraction is an upflow (rising flow), in addition to the SBCR, known reaction types such as a circulating fluidized bed (CFB) reactor, a fluidized bed reactor, or a fixed bed reactor can be used.

[0042] <Dispersion Medium at Startup of FT Reactor> A powdered reaction catalyst (hereinafter referred to as "FT catalyst 16") and hydrocarbons that are liquid near the reaction temperature are set as dispersion media in the FT reactor 10, and the feed gas is introduced from the lower direction of the sparger (gas dispersion section) 12 installed at the bottom of the FT reactor 10. The hydrocarbons set together with the FT catalyst 16 during the reaction preferably have a carbon number of 12 to 50, more preferably 15 to 40, and most preferably 15 to 30. If the carbon number is less than this, the vapor pressure near the reaction temperature will be too high, and if it exceeds this range, operability will be reduced, such as the need to preheat the hydrocarbons before setting them. As the FT reaction progresses, the dispersion medium in the FT reactor 10 is replaced by hydrocarbons (FT oil) synthesized in the FT synthesis reaction.

[0043] <FT Reaction Temperature (Slurry Bed Temperature) and Reaction Pressure> The slurry bed in the FT reactor 10 is maintained at a temperature of 200°C or higher and 270°C or lower, and at a pressure of 0.5 MPa.G or higher and 3 MPa.G or lower. The reaction temperature is preferably 200°C or higher and 270°C or lower, more preferably 210°C or higher and 240°C or lower, and even more preferably 220°C or higher and 240°C or lower. Below these temperatures, CO and CO ２ The conversion rate is low, resulting in low productivity. On the other hand, if the temperature exceeds this range, the gas components consisting of low-carbon number hydrocarbons (e.g., methane to butane) will increase, and the hydrocarbon yield (SAF yield) that satisfies the target carbon number will saturate. The reaction pressure is preferably 0.5 MPa·G to 3 MPa·G, more preferably 0.5 MPa to 2 MPa·G, and most preferably 0.6 MPa to 1.5 MPa·G. Below this pressure range, chain growth tends to be difficult, and there is a risk of a decrease in SAF yield. On the other hand, if the pressure exceeds this range, chain growth will saturate, and the unit consumption will increase due to compression, making the process less technically significant.

[0044] <Agitation Mechanism> The feed gas disperses as bubbles in the hydrocarbons and moves upward, creating an upward flow of liquid hydrocarbons. The upward flow and buoyancy force cause the FT catalyst 16 to be dispersed within the bubble column of the FT reactor 10. In this way, in addition to dispersing the FT catalyst 16 by the upward flow of bubbles and buoyancy force, the FT reactor 10 can also be provided with an agitation mechanism 14. It is also preferable to provide the agitation mechanism 14 with agitator blades 15 to forcibly disperse the FT catalyst 16. The provision of the agitator blades 15 increases the contact efficiency of the feed gas (gas), dispersion medium (liquid), and FT catalyst 16 (solid), allowing the height of the reaction column of the FT reactor 10 to be reduced, thereby saving space in the plant.

[0045] <Catalyst Used in FT Synthesis Reaction> The FT catalyst 16 in this embodiment may be any catalyst that functions as a catalyst for the FT synthesis reaction, and examples thereof include a main catalyst, a catalyst carrier, and an auxiliary catalyst.

[0046] <Main Catalyst> The main catalyst in the FT catalyst 16 is a metal catalyst selected from cobalt, ruthenium, and iron. Iron is inexpensive but has relatively low catalytic activity, while ruthenium is a precious metal with high catalytic activity but is extremely expensive. The products of the FT synthesis reaction using an iron-based catalyst are characterized by a high naphtha content and also contain oxygenated compounds. For this reason, cobalt is most preferably used as the main catalyst to obtain a fraction of saturated hydrocarbons (SAF-equivalent fractions) having the carbon numbers used in diesel, jet fuel (SAF), kerosene, and the like. The amount of the main catalyst, calculated as metal by weight in the FT catalyst 16, is preferably 5 wt% to 25 wt%, more preferably 7.5 wt% to 20 wt%, and even more preferably 8 wt% to 15 wt%. Amounts below this range tend to result in insufficient activity for the FT synthesis reaction, while amounts exceeding this range result in saturation of the activity for the FT synthesis reaction, diminishing the technical significance, particularly in terms of cost.

[0047] <Catalyst Carrier> The catalyst carrier in the FT catalyst 16 is silica (SiO ２ ), alumina (Al ２ O ３), or zeolite (aluminosilicate). Among these, silica is preferably used. Silica is chemically stable and therefore does not affect the main catalyst or auxiliary catalyst. This allows the chemical properties of the main catalyst and auxiliary catalyst to be fully exhibited. Furthermore, since silica has a large specific surface area, it has high contact efficiency with the raw material gas (substrate), allowing the FT synthesis reaction to proceed efficiently. Furthermore, the true density (true specific gravity) of the catalyst support increases in the order of alumina > zeolite > silica. Here, when a bubble column is provided as the FT reactor 10, the smaller the true density (true specific gravity) of the catalyst support, the easier it is for catalyst particles to be dispersed by bubbles. Therefore, silica is considered to be the catalyst support with the best operability in this embodiment.

[0048] <Auxiliary Catalyst> The FT catalyst 16 may contain an auxiliary catalyst in addition to the main catalyst. The auxiliary catalyst is characterized by containing at least one rare earth element selected from the group consisting of yttrium, cerium, lanthanum, praseodymium, neodymium, and holmium; at least one alkali metal selected from the group consisting of sodium, potassium, rubidium, and cesium; at least one alkaline earth metal selected from the group consisting of beryllium, magnesium, calcium, strontium, and barium; and copper. Among these, yttrium, cerium, lanthanum, praseodymium, neodymium, holmium, and copper are preferred, with yttrium, cerium, lanthanum, praseodymium, neodymium, and holmium being more preferred, and yttrium being most preferred. It is believed that the addition of the auxiliary catalyst increases the amount of carbon monoxide and carbon dioxide adsorbed on the catalyst surface and also increases the number of reaction active sites. In the case of copper, charge transfer occurs between the main catalyst (such as cobalt) and copper, causing the oxidation number of the main catalyst to slightly decrease (δ-), resulting in the reduction of CO and CO ２The amount of the auxiliary catalyst is preferably 1 / 30 to 1 / 3 of the weight-based amount of the main catalyst (e.g., cobalt), and more preferably 1 / 20 to 1 / 5.

[0049] <Particle diameter of catalyst> The FT catalyst 16 contained in the FT reactor 10 may be in the form of a fine powder. In this case, the particle shape of the FT catalyst 16 is preferably crushed, ellipsoidal, spherical, cylindrical, or the like, and it is also preferable to use a combination of these shapes. The particle size (longest part of the across length) of the FT catalyst 16 in this embodiment is preferably 0.07 mm or more and 1 mm or less, more preferably 0.07 mm or more and 0.7 mm or less, and even more preferably 0.08 mm or more and 0.17 mm or less.

[0050] <Specific surface area of ​​catalyst> The specific surface area (SA) of the FT catalyst 16 is 100 m ２ / g or more is preferable, and 200m ２ / g or more is more preferable, ２ / g or more is most preferable. There is no particular upper limit on the specific surface area of ​​the FT catalyst 16, but the practical upper limit is 500 m ２ If the amount is less than the lower limit of the range, the active metals related to the main catalyst and the like cannot be sufficiently supported as the FT catalyst 16.

[0051] <Reaction in FT Reactor> As a result of extensive investigations by the present inventors, when an FT catalyst 16 containing cobalt as the main catalyst was used, the FT synthesis reaction using carbon dioxide as a starting material (Equation 3) also proceeded in parallel with the FT synthesis reaction using carbon monoxide as a starting material as shown in Equation 1 above. The reaction formula shown in formula 3 is a general chemical reaction formula, and includes the case where the FT synthesis reaction shown in formula 1 and the reverse water gas shift reaction shown in formula 4 occur in parallel. In other words, Equation 3 is also a chemical reaction equation combining Equations 1 and 4.

[0052] In the FT synthesis reaction section (FT reactor 10), the FT synthesis reaction is allowed to proceed so that the value of the chain growth probability (α) falls within the above-mentioned range (0.65 to 0.85), thereby suppressing the production of hydrocarbons with a large carbon number (particularly, a carbon number of 20 or more), and producing hydrocarbons (FT oil) in which the weight distribution of hydrocarbons with a carbon number of 8 to 16 (fraction corresponding to SAF) is larger than the weight distribution of hydrocarbons with a carbon number of 17 or more.

[0053] <<Saturated Hydrocarbon Recovery Section>> The hydrocarbons (fractions) produced in the FT synthesis reaction section are introduced into the saturated hydrocarbon recovery section. The saturated hydrocarbon recovery section is used to advance the saturated hydrocarbon recovery step described above, and selectively recovers saturated hydrocarbons having 8 to 16 carbon atoms. An example of the saturated hydrocarbon recovery section in this embodiment is one that includes a reflux section for refluxing the saturated hydrocarbons obtained in the FT synthesis reaction section.

[0054] <Reflux Unit> The reflux unit 20 corresponds to the reflux section. The reflux unit 20 is installed downstream of the FT reactor 10 and serves to selectively obtain hydrocarbons having 8 to 16 carbon atoms (a fraction corresponding to SAF). As shown in FIG. 5, the reflux unit 20 may be installed directly above the FT reactor 10, or may be installed next to the FT reactor 10 via an insulated conduit from the top of the FT reactor 10. It is desirable that the conduit be maintained (insulated) at a temperature suitable for the reflux unit 20 by heaters A to D.

[0055] The height of the reflux unit 20 can be reduced by installing plates as shown in Fig. 5 inside the reflux unit 20. Alternatively, metal and / or ceramic Raschig rings may be packed in place of the plates.

[0056] The reflux unit 20 is preferably maintained at a temperature of 110°C to 230°C, more preferably 150°C to 230°C, and most preferably 170°C to 220°C. Below this temperature range, naphtha fraction, which is lighter than the SAF-equivalent fraction, becomes the main component. On the other hand, above this temperature range, the difference between the fraction in the FT reactor 10 and that in the FT reactor 10 becomes small.

[0057] <<Cooling Unit>> The cooling unit 30 serves to cool and condense the SAF-equivalent fraction sent from the reflux unit 20 and collect the fraction in a fraction collector 40 installed downstream of the cooling unit 30. The cooling pipes inside the cooling unit 30 may be straight pipes as shown in FIG. 5 , or may have shapes such as a spiral (snake-like) or a ball-shaped pipe. Cooling fins may also be attached to the cooling pipes. The cooling temperature in the cooling unit 30 is preferably 20°C or higher and 40°C or lower, more preferably 20°C or higher and 35°C or lower, and most preferably 25°C or higher and 35°C or lower. Below this temperature range, the viscosity of hydrocarbons increases in the cooling unit 30, resulting in a decrease in recovery efficiency. On the other hand, above this temperature range, the cut range of hydrocarbons becomes broad.

[0058] <<Fraction Collector>> The fraction collector 40 has the role of storing and recovering the SAF-equivalent fraction that has passed through the cooling unit 30. In addition, a solenoid valve 42 is provided below the fraction collector 40, and the liquid height of the SAF-equivalent fraction is monitored with a level meter. When a certain amount is reached, the fraction may be stored in a product tank via the solenoid valve 42.

[0059] In the hydrocarbon production method and hydrocarbon production apparatus of this embodiment, the reaction conditions in the FT synthesis reaction step (FT synthesis reaction section) are set as follows: a silica-supported cobalt catalyst (Ce-Co / SiO ) containing cerium as an auxiliary catalyst in an amount of 1 / 20 part by weight relative to the Co content (10 wt%); ２ The catalyst to dispersion medium ratio was 3 (w / w)%. The reaction temperature was 230°C, the pressure was 600 kPa, and the G (6 kg / cm ２ , G), and the ratio of the mixed gas (H ２ / CO ratio 2 / 1 (2.0)) per hour, the ventilation volume (vg) is 1,100 to 1,500 (vg / vc·h －１ The FT reaction was carried out by supplying the feed in a range of 190 to 200°C and a pressure of 6 kg / cm. The single-pass conversion rate was 50 to 58%, and the chain propagation probability (α) was 0.75. The saturated hydrocarbon recovery step (saturated hydrocarbon recovery section) was carried out under the following conditions: temperature 190 to 200°C, pressure 6 kg / cm. ２, G, it was possible to selectively recover saturated hydrocarbons having a carbon number of 16 or less. In other words, it was possible to easily produce saturated hydrocarbons having a carbon number (8 to 16) useful as SAF. It goes without saying that the above conditions are merely an example and are not limited to the above conditions.

[0060] According to the hydrocarbon production method and hydrocarbon production apparatus of this embodiment, it is possible to produce a fraction equivalent to SAF without the steps of separating solids including wax and catalyst, upgrading the wax fraction, and distillation. This makes it possible to produce SAF equivalent fractions on-site, more specifically, in a CO2 facility adjacent to an airport, for example. ２ This will enable SAF production at recovery sites and hydrogen production sites, contributing to the spread of carbon-neutral fuels.

[0061] The above-described embodiments show examples of the hydrocarbon production method and hydrocarbon production device. The hydrocarbon production method and hydrocarbon production device according to the present invention are not limited to the above-described embodiments, and the hydrocarbon production method and hydrocarbon production device according to the above-described embodiments may be modified within the scope of the gist of the claims.

[0062] For example, in the above-described embodiment, the reflux temperature in the reflux step (reflux section) of the saturated hydrocarbon recovery step (saturated hydrocarbon recovery section) is set to 110°C or higher and 230°C or lower. This temperature range is suitable for obtaining a fraction useful as SAF, but by setting the temperature range to, for example, 70°C or higher and lower than 110°C, it is also possible to use the temperature range to obtain saturated hydrocarbons useful for other applications, such as a volatile oil fraction (a precursor to gasoline) or a naphtha fraction.

[0063] The hydrocarbon production method and hydrocarbon production apparatus of the present invention can be used as a technology that enables simple on-site production of hydrocarbons (saturated hydrocarbons) having a specific carbon number, and is particularly suitable for use in the production of kerosene and SAF.

[0064] 100 Hydrocarbon production apparatus, 10 FT reactor, 12 Sparger, 14 Stirring mechanism, 15 Stirring blade, 16 FT catalyst, 20 Reflux unit, 30 Cooling unit, 40 Fraction collector, 42 Solenoid valve

Claims

1. A hydrocarbon production method comprising: an FT synthesis reaction step in which a feed gas is supplied into a reaction vessel containing a reaction catalyst to carry out a Fischer-Tropsch synthesis reaction; and a saturated hydrocarbon recovery step in which saturated hydrocarbons having 16 or fewer carbon atoms are selectively recovered, wherein the FT synthesis reaction step is carried out under conditions in which the chain propagation probability (α) in the Fischer-Tropsch synthesis reaction is 0.85 or less.

2. The hydrocarbon production method according to claim 1, wherein the saturated hydrocarbon recovery step includes a reflux step of refluxing the saturated hydrocarbons obtained in the FT synthesis reaction step, and the reflux step is carried out at a temperature of 110°C or higher and 230°C or lower.

3. The hydrocarbon production method according to claim 1, wherein the FT synthesis reaction step is carried out at a reaction temperature of 200°C or higher and 270°C or lower.

4. The hydrocarbon production method according to claim 1, wherein the FT synthesis reaction step is carried out at a reaction pressure of 0.5 MPa·G or more and 3 MPa·G or less.

5. The hydrocarbon production method according to claim 1, characterized in that the reaction catalyst used in the FT synthesis reaction step contains at least one element selected from the group consisting of yttrium, cerium, lanthanum, praseodymium, neodymium, holmium, sodium, potassium, rubidium, cesium, beryllium, magnesium, calcium, strontium, barium, and copper.

6. The hydrocarbon production method according to claim 5, wherein the reaction catalyst contains at least one selected from the group consisting of cobalt, ruthenium, and iron.

7. The hydrocarbon production method according to claim 1, wherein the value of the chain propagation probability (α) is 0.72 to 0.

78.

8. A hydrocarbon production system comprising: an FT synthesis reaction section in which a raw material gas is supplied into a reaction vessel containing a reaction catalyst to carry out a Fischer-Tropsch synthesis reaction; and a saturated hydrocarbon recovery section in which saturated hydrocarbons having 16 or less carbon atoms are selectively recovered, wherein the FT synthesis reaction section is operated under conditions in which the chain propagation probability (α) in the Fischer-Tropsch synthesis reaction is 0.85 or less.

9. The hydrocarbon production apparatus according to claim 8, wherein the saturated hydrocarbon recovery section includes a reflux section for refluxing the saturated hydrocarbons obtained in the FT synthesis reaction section, and the reflux section is maintained at a temperature of 110°C or higher and 230°C or lower.

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