Method for producing light olefins

Abstract

This invention provides a method for stably producing light olefins by combining naphtha cracking and alcohol conversion. [Solution] The method includes a cracking step to obtain a naphtha cracking fraction in a cracking furnace, a step to obtain a conversion fraction containing ethylene-propylene by contacting a raw material containing ethanol with a catalyst, and a consolidation step to combine at least a portion of the naphtha cracking fraction or a fraction derived therefrom, and the ethanol conversion fraction or a fraction derived therefrom, respectively, wherein in the cracking step, the operating conditions of at least one of the cracking furnaces are expressed by the following equation Δ(cracking furnace parameter) = 0.0059 × [COT(0) - COT(t)] - 0.0726 × [S / N(0) - S / N(t)] + 0.0687 × [P(0) - P(t)], and the Δ(cracking furnace parameter) is expressed by the following equation CR × Δ(cracking furnace parameter) - ER × [P / E E (0)-P / E E It is controlled so that (t)≧0.

Description

[Technical Field]

[0001] This invention relates to a method for producing light olefins. [Background technology]

[0002] Various chemicals, such as monomer raw materials, have been produced by cracking naphtha obtained from petroleum. Among these chemicals, light olefins such as ethylene and propylene are in particularly high demand due to their wide variety of applications. Of these, propylene is of high value, and methods for selectively producing propylene from naphtha have been studied, with steam cracking being a well-known example (for example, Patent Document 1).

[0003] Methods for obtaining light olefins from alcohols using catalysts such as zeolites have been reported. For example, Patent Document 2 proposes a method for efficiently and stably producing propylene by contacting at least one raw material selected from ethylene and ethanol with a catalyst containing an intermediate pore size zeolite in a fluidized bed reactor. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2016-117800 [Patent Document 2] International Publication No. WO2009 / 037992 [Overview of the project] [Problems that the invention aims to solve]

[0005] In the petrochemical industry, it is important to stably supply the product, light olefins, to the market. To stabilize the production volume of light olefins, for example, in naphtha cracking, multiple cracking furnaces are operated in parallel. Also, in the production method of light olefins, various components are separated and purified, but fluctuations in the production volume significantly deteriorate the purification efficiency of light olefins.

[0006] To achieve a reduction in environmental impact, in today's chemical industry, it is required to replace products obtained from petroleum with those from renewable raw materials. In particular, in the production method of light olefins, it is expected to convert naphtha into alcohol raw materials. On the other hand, in the method of obtaining light olefins from alcohol, the production volume of light olefins fluctuates due to the deterioration of the catalyst over time.

[0007] An object of the present invention is to provide a method for producing light olefins that can stably produce light olefins by combining naphtha cracking and alcohol conversion.

Means for Solving the Problems

[0008] The present inventors have found that, in the method for producing light olefins, the above problems can be solved by controlling the operating conditions of naphtha cracking in accordance with the change in the production volume by alcohol conversion.

[0009] The present invention includes the following embodiments. [1] A cracking step of introducing a naphtha raw material into a cracking furnace to obtain a naphtha cracked fraction, an ethanol conversion step of introducing a raw material containing ethanol into a reactor and bringing it into contact with a catalyst to obtain an ethanol conversion fraction containing ethylene and propylene, and a merging step of merging at least a part of the naphtha cracked fraction or a fraction derived therefrom and at least a part of the ethanol conversion fraction or a fraction derived therefrom to obtain a merged fraction, In the cracking step, among the cracking furnaces, the operating conditions of at least one cracking furnace are Δ (cracking furnace parameter) of the formula (1): <Δ(cracking furnace parameters)=0.0059×[COT(0)-COT(t)]-0.0726×[S / N(0)-S / N(t)]+0.0687×[P(0)-P(t)]...(1) (However, COT(t) represents the decomposition furnace outlet temperature at a certain point in time, COT(0) represents the decomposition furnace outlet temperature at the start of catalyst use, S / N(t) represents the steam naphtha ratio at a certain point in time, S / N(0) represents the steam naphtha ratio at the start of catalyst use, P(t) represents the total pressure inside the decomposition furnace at a certain point in time, and P(0) represents the total pressure inside the decomposition furnace at the start of catalyst use.) This is expressed as follows, where the aforementioned Δ (decomposition reactor parameter) is given by equation (2): CR × Δ (decomposition reactor parameters) - ER × [P / E E (0)-P / E E (t)]≧0···(2) (However, P / E E (t): Mass ratio of propylene to ethylene in the ethanol conversion fraction at a given time, P / E E (0): Represents the mass ratio of propylene to ethylene in the ethanol conversion fraction at the start of catalyst use. ER: Represents the mass ratio of ethylene production in the ethanol conversion process to the total ethylene production at the start of catalyst use. CR: Represents the mass ratio of ethylene production in the controlled cracking furnace to the total ethylene production at the start of catalyst use. A method for producing light olefins, controlled to satisfy the following conditions.

[0010] [2] In the cracking process, the Δ (cracking furnace parameter) is given by equation (3): CR × Δ (decomposition reactor parameters) - ER × [P / E E (0)-P / E E (t)] ≤ 0.050 ···(3) A method for producing a light olefin according to [1], which is controlled to satisfy the following conditions.

[0011] [3] In the at least one decomposition furnace, the decomposition furnace outlet temperature at any point in time during the operation of the decomposition furnace is given by equation (4): CR×0.0059×[COT(0)-COT(t)]-ER×[P / E E (0)-P / EE (t) ≥ 0 ··· (4) The method for producing light olefins according to [1] or [2], which is controlled to satisfy the above conditions.

[0012] [4] In the at least one cracking furnace, the cracking furnace outlet temperature at any point during the operation of the cracking furnace is controlled to satisfy the range of 700 to 1000 °C. The method for producing light olefins according to any one of [1] to [3].

[0013] [5] The method for producing light olefins according to any one of [1] to [4], wherein the mass ratio ER is 0.20 or more.

[0014] [6] The ethanol conversion fraction satisfies the formula (5): P / E E (0) - P / E E (t) ≤ 0.40 ··· (5) The method for producing light olefins according to any one of [1] to [5], wherein the catalyst is updated to satisfy the above conditions.

[0015] [7] The method for producing light olefins according to any one of [1] to [6], wherein the catalyst is a zeolite-containing catalyst.

Advantages of the Invention

[0016] According to the present invention, a method for producing light olefins that can stably supply olefins having 2 or 3 carbon atoms can be provided.

Brief Description of the Drawings

[0017] [Figure 1] Figure 1 is a block diagram showing the outline of the method for producing light olefins according to the present embodiment. [Figure 2] Figure 2 is a schematic configuration diagram of the production equipment used in the method for producing light olefins according to the present embodiment. [Figure 3] Figure 3 is a schematic configuration diagram of a fixed-bed single-stage adiabatic reactor. [Figure 4]Figure 4 is a graph showing the results of Reference Example 1. [Figure 5] Figure 5 is a graph showing the results of Reference Example 1. [Figure 6] Figure 6 is a graph showing the results of Reference Example 2. [Figure 7] Figure 7 is a graph showing the results of Reference Example 2. [Figure 8] Figure 8 is a graph showing the results of Reference Example 3. [Figure 9] Figure 9 is a graph showing the results of Reference Example 3. [Modes for carrying out the invention]

[0018] The present invention will be described in detail below. However, the present invention is not limited to the following embodiments (this embodiment), and can be implemented with various modifications within the scope of its gist.

[0019] Numerical ranges indicated using "~" represent a range that includes the numbers before and after "~" as the minimum and maximum values, respectively. In numerical ranges described stepwise in this specification, the upper or lower limit of a numerical range in one step can be arbitrarily combined with the upper or lower limit of a numerical range in another step.

[0020] Modifiers such as "first" and "second" may be used to distinguish elements, but such modifiers do not necessarily indicate any particular order.

[0021] <Method for producing light olefins> The method for producing a light olefin according to this embodiment includes a cracking step of introducing naphtha raw materials into a cracking furnace to obtain a naphtha cracking fraction; an ethanol conversion step of introducing ethanol-containing raw materials into a reactor and contacting them with a catalyst to obtain an ethanol conversion fraction containing ethylene and propylene; and a consolidation step of combining at least a portion of the naphtha cracking fraction or a fraction derived therefrom with at least a portion of the ethanol conversion fraction or a fraction derived therefrom to obtain a combined fraction.

[0022] The method for producing light olefins according to this embodiment will be outlined. Figure 1 is a schematic block diagram of the method for producing light olefins according to this embodiment. As shown in Figure 1, the production method according to this embodiment includes a naphtha cracking process N and an ethanol conversion process E.

[0023] In the naphtha cracking process N, naphtha is thermally decomposed in naphtha cracking N1, and then subjected to the naphtha cracking fraction purification process N2, where ethylene and propylene are separated by cryogenic separation N3. In cryogenic separation N3, the treated fraction is cooled, and ethylene and propylene are liquefied to separate gaseous methane and hydrogen from liquid olefins. In cryogenic separation N3, since the liquefaction of relatively light fractions within the naphtha cracking fraction is required, the fraction needs to be pressurized and cooled, and a large amount of energy is required for the process.

[0024] In naphtha cracking process N, existing naphtha cracker equipment may be used. For example, the ethanol conversion fraction obtained by the ethanol conversion process described later is introduced into the naphtha cracker equipment.

[0025] The naphtha cracking process N may include any steps, but the steps described below may include, for example, a cracking step, a first cooling step, a second cooling step, a confluence step, a first compression step, a washing step, and a cryogenic separation step.

[0026] The ethanol conversion process E includes, for example, a step of converting a raw material containing ethanol into an ethanol conversion fraction containing ethylene and propylene, etc. By using bioethanol as a raw material in the ethanol conversion process E, a biomass-derived ethanol conversion fraction can be obtained. By connecting the ethanol conversion process E to an existing facility that performs the naphtha cracking process N, a portion of the petroleum-derived raw material can be replaced with biomass-derived raw material.

[0027] The ethanol conversion process E may include any steps, but the steps described later may include, for example, an ethanol conversion step, a purification step, a third cooling step, a second compression step, a distillation step, and a recycling step.

[0028] In ethanol conversion process E, an ethanol conversion fraction is obtained by contacting an ethanol-containing raw material with a catalyst. However, the composition of the obtained ethanol conversion fraction fluctuates due to the deterioration of the catalyst over time. Generally, light olefins are liquefied by compression and cooling, and each product is obtained by distillation of the liquefied light olefin. However, if the production volume fluctuates, the operating efficiency deteriorates significantly due to compressor surging and distillation column flooding. Therefore, in this embodiment, fluctuations in the production volume of light olefins are suppressed by changing the operating conditions of the naphtha cracking process in accordance with the fluctuations in the composition of the ethanol conversion fraction. Furthermore, by suppressing fluctuations in the production volume of light olefins, the purification efficiency of light olefins is improved.

[0029] In this embodiment, we focused on the change in the mass ratio (P / E) of propylene to ethylene as a variation in the composition of the ethanol conversion fraction. That is, the P / E ratio in the ethanol conversion fraction at the start of catalyst use. E (0) and P / E in the ethanol conversion fraction at a certain point in time E The difference from (t) was considered as the range of variation in composition during the ethanol conversion process. To consider the impact of the ethanol conversion process on the overall light olefin manufacturing method, the amount of ethylene produced in the ethanol conversion process at the start of catalyst use was multiplied by the mass ratio ER of the amount of ethylene produced in the manufacturing method, and ER × [P / E E (0)-P / E E (t) was defined as "the effect of catalyst degradation in the ethanol conversion process on the amount of light olefin produced."

[0030] Next, to investigate the influence of the operating conditions of the cracking furnace on the composition of the naphtha cracked fraction, repeated experimental studies were conducted. As a result, it was found that there is a correlation between the cracking furnace outlet temperature (COT), steam-naphtha ratio (S / N), total pressure inside the cracking furnace (P), and the composition of the naphtha cracked fraction. Therefore, a sensitivity analysis of the composition of the naphtha cracked fraction for each parameter of COT, S / N, and P was performed as shown in the reference example below, and the sum of the effects of each parameter was set to Δ (cracking parameter). From the results of the sensitivity analysis, it was found that Δ (cracking parameter) is used as the operating condition for at least one of the cracking furnaces in equation (1): Δ(cracking furnace parameters)=0.0059×[COT(0)-COT(t)]-0.0726×[S / N(0)-S / N(t)]+0.0687×[P(0)-P(t)]...(1) (However, in equation (1), COT(t): decomposition furnace outlet temperature at a certain point in time, COT(0): decomposition furnace outlet temperature at the start of catalyst use, S / N(t): steam naphtha ratio at a certain point in time, S / N(0): steam naphtha ratio at the start of catalyst use, P(t): total pressure inside the decomposition furnace at a certain point in time, P(0): total pressure inside the decomposition furnace at the start of catalyst use.) It was represented as follows. When adjusting the operating conditions of the cracking furnace, in order to consider the impact on the overall light olefin production method, at the start of catalyst use, the mass ratio CR of the amount of ethylene produced by the cracking furnace under control to the total amount of ethylene produced was multiplied by Δ (cracking furnace parameter), and CR × Δ (cracking furnace parameter) was defined as "the impact of cracking furnace control on the amount of light olefin produced."

[0031] The inventors conceived the idea that fluctuations in the amount of light olefins produced can be suppressed by controlling the cracking furnace so that "the effect of cracking furnace control on the amount of light olefins produced" is equal to or greater than "the effect of catalyst degradation in the ethanol conversion process on the amount of light olefins produced." In other words, in the method for producing light olefins according to this embodiment, Δ (decomposition parameter) is given by equation (2): CR × Δ (decomposition reactor parameters) - ER × [P / E E (0)-P / E E (t)]≧0···(2) (However, in equation (2), P / E E (t): Mass ratio of propylene to ethylene in the ethanol conversion fraction at a given time, P / E E (0): The mass ratio of propylene to ethylene in the ethanol conversion fraction at the start of catalyst use. ER: The mass ratio of ethylene produced in the ethanol conversion process to the total ethylene produced at the start of catalyst use. CR: The mass ratio of ethylene produced in the controlled cracking furnace to the total ethylene produced at the start of catalyst use. By controlling the decomposition furnace to satisfy the following conditions, fluctuations in the amount of light olefins produced are suppressed.

[0032] Among these, because it excels in the production efficiency of light olefins, Δ (decomposition parameter) is given by equation (3): CR × Δ (decomposition reactor parameters) - ER × [P / E E (0)-P / E E (t)] ≤ 0.050 ···(3) It is more preferable to control the decomposition furnace to satisfy the following conditions.

[0033] Among these, it is preferable to control the cracking furnace outlet temperature because it is superior in terms of propylene production efficiency. In other words, in the method for producing light olefins of this embodiment, the cracking furnace outlet temperature at any point during the operation of the cracking furnace (naphtha cracking) is determined by equation (4): CR×0.0059×[COT(0)-COT(t)]-ER×[P / E E (0)-P / E E (t)]≧0···(4) It is preferable to control the cracking furnace to satisfy the following condition. In this specification, "any point in time during operation (naphtha cracking)" means any point in time between the catalyst start time and the catalyst replacement time in the ethanol conversion process. For example, in the above case, it means that the cracking furnace should be controlled so that equation (4) is satisfied at any point in time between the catalyst start time and the catalyst replacement time in the ethanol conversion process. As will be described later, the catalyst in the ethanol conversion process is replaced periodically in order to maintain a constant composition of the ethanol conversion fraction.

[0034] The mass ratio ER of the amount of ethylene produced in the ethanol conversion process at the start of catalyst use to the total amount of ethylene produced is preferably 0.20 or higher, more preferably 0.30 or higher, and even more preferably 0.40 or higher, as this is more environmentally friendly.

[0035] "Light olefin" refers to at least one selected from the group consisting of ethylene and propylene. The light olefin is the target compound in the production method according to this embodiment, but from the viewpoint of making better use of the features of the production method according to this embodiment, propylene is preferred.

[0036] In relation to a specific fraction, "fraction derived therefrom" means a fraction obtained by undergoing some process such as distillation, cooling, or compression with respect to that specific fraction. Regarding the components of a fraction, "mainly contains" means that it is contained in more than 50% by mass of that fraction.

[0037] The following describes each step in the method for producing the light olefin according to this embodiment.

[0038] <Naphtha Cracking Process> The method for producing light olefins according to this embodiment includes, as the naphtha cracking process N described above, a cracking step of introducing naphtha raw materials into a cracking furnace to obtain naphtha cracked fractions, and a cryogenic separation step of introducing the obtained naphtha cracked fractions or fractions derived therefrom into a cryogenic separation facility to separate ethylene and propylene.

[0039] Furthermore, the method for producing light olefins according to this embodiment may optionally include, as the naphtha cracking process N described above, a first cooling step in which the naphtha cracked fraction is introduced into a first cooling tower to obtain a first cooling fraction mainly containing olefins with 6 or fewer carbon atoms, and a second cooling step in which the first cooling fraction is introduced into a second cooling tower to obtain a second cooling fraction mainly containing olefins with 4 or fewer carbon atoms. By providing the first cooling step and / or the second cooling step prior to the washing step described later, the fraction introduced into the soda washing tower can be further reduced, and the washing efficiency in the soda washing tower can be further improved. In addition, by providing the cooling step in two stages, it becomes easier to control the temperature and composition of the fraction obtained in the cooling step.

[0040] Furthermore, the method for producing light olefins according to this embodiment may optionally include, as the naphtha cracking process N described above, a first compression step in which the fraction is pressurized before being introduced into the cryogenic separation equipment, and a washing step in which the fraction is introduced into a soda washing tower to obtain a washed fraction. In the soda washing tower, acidic components such as carbon dioxide contained in the fraction can be removed, thereby further improving the separation efficiency in the cryogenic separation process. In addition, by providing the first compression step prior to the washing step, the volume of fraction introduced into the soda washing tower can be reduced, thereby further improving the operating efficiency of the soda washing tower.

[0041] <Ethanol Conversion Process> The method for producing light olefins according to this embodiment includes an ethanol conversion step, as the ethanol conversion process E described above, in which a raw material containing ethanol is introduced into a reactor and brought into contact with a catalyst to obtain an ethanol conversion fraction containing ethylene and propylene.

[0042] The method for producing light olefins according to this embodiment may optionally include a purification step as the ethanol conversion process E described above, in which the ethanol conversion fraction is purified to obtain a purified ethanol conversion fraction. By including a purification step, the concentration of the target compound contained in the ethanol conversion fraction can be increased, and the purification efficiency in the cryogenic separation step can be further improved.

[0043] On the other hand, the method for producing light olefins according to this embodiment may optionally include a third cooling step as a purification step in the ethanol conversion process E described above, in which the ethanol conversion fraction is introduced into a third cooling tower to obtain a cooled ethanol conversion fraction mainly containing olefins with 6 or fewer carbon atoms. By providing a third cooling step, the amount of hydrocarbons with 7 or more carbon atoms contained in the ethanol conversion fraction or fraction derived therefrom can be reduced, and the purification efficiency in the cryogenic separation step can be further improved.

[0044] The method for producing light olefins according to this embodiment may optionally include a compression separation step as a purification step in the ethanol conversion process E described above, in which the cooled ethanol conversion fraction is pressurized by a compressor to obtain a light ethanol conversion fraction mainly containing olefins with 3 or fewer carbon atoms as a gas component, and a heavy ethanol conversion fraction mainly containing olefins with 4 or more carbon atoms as a liquid component. By providing a compression separation step, the amount of hydrocarbons with 4 or more carbon atoms contained in the ethanol conversion fraction or fraction derived therefrom can be reduced, and the purification efficiency in the cryogenic separation step can be further improved.

[0045] The method for producing light olefins according to this embodiment may optionally include a recycling step as the ethanol conversion process E, in which at least a portion of the heavy ethanol conversion fraction described above is introduced into the reactor as part of the raw materials. By providing a recycling step, the olefins contained in the heavy ethanol conversion fraction can be converted into the target compound, and the production efficiency of ethylene and propylene per unit of raw material ethanol is further improved.

[0046] <Merge process> The method for producing light olefins according to this embodiment includes a consolidation step in which at least a portion of a naphtha decomposition fraction or a fraction derived therefrom is combined with at least a portion of an ethanol conversion fraction or a fraction derived therefrom to obtain a combined fraction. This merging process is carried out at one of the stages in the naphtha cracking process N, as described later.

[0047] In the above-described embodiment, for the purpose of explaining the organization of each step, the process was divided into general categories of naphtha cracking process N and ethanol conversion process E in the present technical field. However, each step according to this embodiment may belong to either naphtha cracking process N or ethanol conversion process E.

[0048] The method for producing light olefins according to this embodiment can be realized, for example, by the production equipment shown in Figure 2. The light olefin production equipment includes a cracking furnace 11, a first cooling tower 12, a second cooling tower 13, a first compressor 14, a soda washing tower 15, and a cryogenic separation unit 16. Alternatively, the light olefin production equipment may include a reactor 21, a third cooling tower 22, a second compressor 23, a distillation tower 24, and a condenser 25. In Figure 2, there is one cracking furnace, but the light olefin production equipment may have one or more cracking furnaces. In that case, the operating conditions of at least one of the cracking furnaces are controlled so that at least Δ (cracking furnace parameter) in equation (1) satisfies equation (2). Alternatively, the operating conditions of one or more of the cracking furnaces, or the operating conditions of all of the cracking furnaces, may be controlled so that at least Δ (cracking furnace parameter) in equation (1) satisfies equation (2).

[0049] The following describes each step according to this embodiment in detail, using the manufacturing equipment shown in Figure 2 as an example.

[0050] <Cracking Process> In the cracking furnace 11, the aforementioned cracking process is carried out.

[0051] (Naphtha raw material) In the method for producing light olefins according to this embodiment, naphtha raw materials are used. The naphtha raw materials contain at least naphtha. Naphtha is a mixture of hydrocarbons with a boiling point range of about 30 to 230°C, and is classified into light naphtha and heavy naphtha depending on its boiling point range, but either can be used. The naphtha raw materials preferably contain hydrocarbons having 2 to 40 carbon atoms, more preferably hydrocarbons having 2 to 30 carbon atoms, and even more preferably hydrocarbons having 5 to 12 carbon atoms. The boiling point of the naphtha raw materials may be, for example, in the range of 30 to 230°C. The naphtha raw materials are not particularly limited, but are generally obtained by refining petroleum. Bionaphtha obtained by the decomposition of animal and vegetable oils can also be used.

[0052] The naphtha feedstock preferably includes diluting steam from the viewpoint of further reducing the amount of coke produced as a by-product. During the operation of the cracking furnace (naphtha cracking), the supply amount of diluting steam is continuously controlled to satisfy a mass ratio (S / N, steam-naphtha ratio) of 1.0 or less to naphtha, more preferably in the range of 0.10 to 1.0, in order to achieve excellent thermal efficiency. In this specification, "continuously during operation (naphtha cracking)" means that this state is continuously controlled from the time of catalyst initiation to the time of catalyst replacement in the ethanol conversion process. For example, in the above case, it means that the supply amount of diluting steam is continuously controlled by the cracking furnace to satisfy the above range from the time of catalyst initiation to the time of catalyst replacement in the ethanol conversion process.

[0053] While there are no particular limitations on the decomposition method in the cracking process, examples include the steam cracking method, which involves thermal decomposition by contacting naphtha with heated naphtha steam, and the moving bed method, which involves thermal decomposition by contacting naphtha with a granular heat transfer medium heated to a high temperature in a moving bed. An example of the steam cracking method is the tube heating method, in which naphtha and steam are circulated through a heating tube, and thermal decomposition occurs due to heating from the tube wall. Furthermore, catalysts may be used in each method to promote thermal decomposition.

[0054] During naphtha cracking, the cracking furnace outlet temperature (COT) at any given point in time is preferably set to a range of 700 to 1000°C, more preferably to a range of 750 to 950°C, and even more preferably to a range of 775 to 900°C. This temperature range allows for better selectivity of light olefins, resulting in more efficient thermal decomposition of naphtha and suppression of the formation of light components such as methane.

[0055] During operation (naphtha cracking), the total pressure (P, reaction pressure) inside the cracking furnace is preferably 0.5 to 5.0 kg / cm². 2 To satisfy the range, more preferably 1.0 to 2.5 kg / cm³ 2 The decomposition furnace is controlled to satisfy the specified range.

[0056] According to this embodiment, the mass ratio of ethylene to propylene in the naphtha cracking fraction (P / E N The voltage is continuously controlled during the operation of the cracking furnace (naphtha cracking) to preferably be in the range of 0.2 to 1.0, and more preferably in the range of 0.3 to 0.8. According to this embodiment, the yield of light olefins tends to be better.

[0057] <First Cooling Process> The naphtha cracked fraction obtained in the cracking furnace 11 is introduced into the first cooling tower 12. Alternatively, before introducing it into the first cooling tower 12, light olefins such as ethylene and propylene recycled from the downstream refining equipment may be mixed with the naphtha cracked fraction. In the first cooling tower 12, the first cooling process described above is performed to obtain a first cooled fraction mainly containing olefins with 6 or fewer carbon atoms. By cooling the naphtha cracked fraction in the first cooling tower 12, the progress of excessive cracking can be further suppressed, and at least some of the olefins with more than 6 carbon atoms can be removed.

[0058] In the first cooling tower 12, it is preferable to cool by bringing heavy oil, cracked gasoline, or a mixture thereof into contact with naphtha cracked fraction.

[0059] The temperature of the first cooled fraction after processing in the first cooling tower 12 is preferably 50 to 300°C, more preferably 100 to 200°C, and even more preferably 105 to 160°C, from the viewpoint of achieving superior removal efficiency of olefins with more than 6 carbon atoms.

[0060] <Second cooling process> The first cooled fraction obtained in the first cooling tower 12 is introduced into the second cooling tower 13. In the second cooling tower 13, the aforementioned second cooling process is carried out, and by cooling the first cooled fraction, at least a portion of the olefins with more than 4 carbon atoms is removed, and a second cooled fraction mainly containing olefins with 4 or fewer carbon atoms is obtained. At this time, a second heavy fraction mainly containing hydrocarbons with 5 or more carbon atoms and water are mainly obtained from the bottom of the tower.

[0061] In the second cooling tower 13, it is preferable to cool the first cooling fraction by bringing it into contact with water. The temperature of the second cooled fraction after processing in the second cooling tower 13 is preferably 10 to 100°C, more preferably 30 to 90°C, from the viewpoint of achieving superior removal efficiency of olefins with more than 4 carbon atoms.

[0062] <First Compression Process> The second cooled fraction obtained in the second cooling tower 13 is introduced into the first compressor 14. In the first compressor 14, the aforementioned compression process is performed to increase the pressure of the second cooled fraction. The first compression process may be performed before introduction to the cryogenic separation equipment, but it is preferable that the fraction including the second cooled fraction is introduced into the first compressor 14 after the second cooling process. In the first compressor 14, for example, the second cooled fraction may be increased in pressure by a single compressor, or it may be increased in pressure in stages by multiple compressors, for example, 2 to 4 compressors. In the first compression process, in addition to increasing the pressure of the second cooled fraction as a gaseous component, a liquid component may be obtained in which high-boiling-point components contained in the second cooled fraction, such as hydrocarbons with 5 or more carbon atoms, have been liquefied. In this way, by removing high-boiling-point components by increasing the pressure, the concentration of olefins with 3 or fewer carbon atoms in the second cooled fraction can be further increased.

[0063] The pressure of the second cooled fraction after processing by the first compressor 14 is preferably 0.10 to 10.0 MPaG, more preferably 0.20 to 5.0 MPaG, and even more preferably 0.50 to 1.5 MPaG.

[0064] <First Circulation Process> The method for producing light olefins according to this embodiment may include a first circulation step in which at least a portion of the second heavy fraction, which mainly contains hydrocarbons with 5 or more carbon atoms, from the second cooling step is introduced into the first cooling tower. The second heavy fraction contains heavy target compounds such as aromatic compounds. Increasing the amount of the second heavy fraction circulated to the first cooling tower in the first circulation step reduces the production efficiency of these heavy target compounds. On the other hand, increasing the circulation amount allows a portion of the olefins with 4 or fewer carbon atoms contained in the second heavy fraction to be introduced into the cryogenic separation step, thereby further improving the production efficiency of these olefins. Therefore, it is preferable to determine the circulation amount in the first circulation step considering the production balance between heavy target compounds such as aromatic compounds and olefins with 4 or fewer carbon atoms. From the viewpoint of excellent propylene production efficiency, the circulation amount in the first circulation step is preferably 20 to 90% by mass, more preferably 30 to 90% by mass, and even more preferably 40 to 90% by mass relative to the second heavy fraction.

[0065] <Second Cycle Process> The method for producing light olefins according to this embodiment may include a second circulation step in which at least a portion of the second heavy fraction, which mainly contains hydrocarbons with 5 or more carbon atoms, from the second cooling step is introduced into a second cooling tower. In this circulation step, the liquid components generated in the first compression step described above may be combined and introduced into the second cooling tower. The second heavy fraction contains heavy target compounds such as aromatic compounds. Increasing the amount of the second heavy fraction circulated to the first cooling tower in the first circulation step further reduces the production efficiency of these heavy target compounds. On the other hand, increasing the circulation amount allows a portion of the olefins with 4 or fewer carbon atoms contained in the second heavy fraction to be introduced into the cryogenic separation step, thereby improving the production efficiency of these olefins. Therefore, it is preferable to determine the circulation amount in the second circulation step while considering the production balance between heavy target compounds such as aromatic compounds and olefins with 4 or fewer carbon atoms. From the viewpoint of achieving superior propylene production efficiency, the amount of material circulated in the second circulation process is preferably 20 to 90% by mass, more preferably 30 to 90% by mass, and even more preferably 40 to 90% by mass, relative to the total amount of liquid components in the first compression process and the second heavy fraction.

[0066] <Washing process> In the washing process, the fraction is introduced into the soda washing tower 15 before the cryogenic separation equipment is introduced to obtain a washing fraction. In the washing process, acidic components such as carbon dioxide can be removed from the fraction by treatment in the soda washing tower 15. Since carbon dioxide has a higher boiling point than ethylene, if carbon dioxide is introduced into the cryogenic separation, it becomes difficult to separate the olefin from carbon dioxide. Therefore, it is preferable to remove carbon dioxide from the fraction before introducing it into the cryogenic separation equipment. The washing process can be performed before introduction into the cryogenic separation equipment, but it is preferable to provide it after the first compression process in order to make the operation of the soda washing tower easier.

[0067] In the soda washing tower 15, it is preferable to obtain a washing fraction by bringing the fraction into contact with an aqueous sodium hydroxide solution. The amount of sodium hydroxide can be appropriately selected to remove acidic components such as carbon dioxide from the fraction.

[0068] <Cryogenic separation process> In the cryogenic separation process, the fraction is introduced into the cryogenic separation equipment to separate ethylene and propylene. Here, the fraction introduced in the washing process or the cryogenic separation process is preferably the combined fraction or a fraction derived therefrom. The "combined fraction" is the fraction obtained by the aforementioned combining process. Here, "a fraction derived therefrom" means the fraction obtained by further purifying the combined fraction using purification equipment such as a soda washing tower.

[0069] Cryogenic separation generally involves separating components by performing distillation operations under extremely low temperatures and high pressure. For example, under extremely low temperatures and high pressure, a fraction is liquefied to separate hydrogen and methane from light olefins.

[0070] In the cryogenic separation process, ethylene and light olefins such as propylene are further separated through demethane columns, ethane columns, ethylene rectification columns, propane columns, and propylene rectification columns. The naphtha cracker purification system includes both a front-end demethanizer system and a front-end depropanizer system. An example of the equipment configuration in each system is described below, but the presence and order of each separation column are not limited to this example.

[0071] In a front-end demethanizer purification system, for example, light olefins are purified by the following procedure. First, the introductory fraction, compressed by a compressor, is introduced into a condenser, thereby liquefying at least a portion of the light olefins in the introductory fraction and removing at least a portion of the hydrogen. This fraction is introduced into a demethane column, where a demethane fraction mainly containing light olefins is obtained from the bottom of the column, and an off-gas fraction containing hydrogen and methane is obtained from the top of the column. The obtained demethane fraction is introduced into an ethane column, where an ethylene fraction mainly containing ethylene is obtained from the top of the column, and an ethane fraction mainly containing olefins with 3 or more carbon atoms is obtained from the bottom of the column. The obtained ethylene fraction is introduced into an ethylene rectification column, where purified ethylene is obtained by separating ethylene from ethane. The obtained ethane fraction is introduced into a propane column, where a propylene fraction mainly containing propylene is obtained from the top of the column, and a propane fraction mainly containing olefins with 4 or more carbon atoms is obtained from the bottom of the column. The obtained propylene fraction is introduced into a propylene rectification column to separate propylene from propane and obtain purified propylene. The resulting depropane fraction is introduced into a debutane column to obtain a carbon-4 olefin.

[0072] In a front-end depropanizer purification system, light olefins are purified using the following procedure, for example. In a front-end depropanizer purification system, the fraction is separated into an introduction fraction mainly containing hydrocarbons with 3 or fewer carbon atoms and a bypass fraction mainly containing hydrocarbons with 3 or more carbon atoms. This reduces the amount introduced into the cryogenic separation process and thus reduces energy consumption related to cryogenic separation. In other words, for example, in a front-end depropanizer purification system, the fraction is introduced into a first distillation column to separate the introduction fraction that will be introduced into the cryogenic separation process. A bypass fraction is also obtained from the bottom of the first distillation column to bypass the cryogenic separation process and be introduced into the downstream equipment. In the first distillation column, for example, the separation operation may be carried out using a single distillation column, or it may be carried out in stages using multiple distillation columns, for example, 2 to 4 columns. The obtained introduction fraction is then compressed by a compressor and introduced into a condenser, thereby liquefying at least a portion of the light olefins in the introduction fraction and removing at least a portion of the hydrogen. After cooling and compressing the introduced fraction, the target compound can be separated from it by processing it in the same way as in a front-end demethanizer purification system. In addition, in a front-end depropanizer purification system, the introduced fraction obtained from the first distillation column can be further purified by introducing it into a deethane column before being introduced into the cryogenic separation process. In this way, by performing purification of the introduced fraction in addition to the first distillation column, the energy consumption related to the cryogenic separation process can be further reduced.

[0073] <Ethanol conversion process> A raw material containing ethanol is introduced into reactor 21, and the aforementioned ethanol conversion process is carried out. In reactor 21, the raw material containing ethanol is brought into contact with a catalyst to obtain an ethanol conversion fraction containing ethylene and propylene.

[0074] (Raw material: Ethanol conversion process) In the ethanol conversion process, raw materials containing ethanol are used. Ethanol produced by various methods can be used. Among these, bioethanol is preferred from the viewpoint of superior environmental compatibility. In recent years, the importance of replacing fossil resources such as crude oil with renewable plant-derived resources has been recognized anew in order to realize a sustainable society and reduce greenhouse gas emissions. Therefore, in the method for producing light olefins of this embodiment, by using ethanol obtained from renewable resources, it becomes possible to produce chemicals that have conventionally been produced using fossil resources such as crude oil from renewable resources.

[0075] The ethanol content in the raw materials is preferably 30 to 100% by mass, more preferably 40 to 100% by mass, and even more preferably 50 to 100% by mass, relative to the total amount of raw materials.

[0076] The raw materials may include ethylene and ethanol. By using these raw materials, propylene can be produced in higher yield by using an adiabatic reactor and controlling the temperature inside the reactor. The raw materials may also contain olefins having 4 to 6 carbon atoms.

[0077] In the raw materials, the molar ratio of ethylene / ethanol is preferably 0.05 to 2.5, more preferably 0.20 to 2.0, even more preferably 0.30 to 1.8, and even more preferably 0.30 to 1.5.

[0078] In the ethanol conversion process, the raw materials may include olefins having 4 to 6 carbon atoms and oxygen-containing compounds having 1 to 6 carbon atoms other than ethanol. Examples of oxygen-containing compounds having 1 to 6 carbon atoms other than ethanol include methanol, propanol, dimethyl ether, and diethyl ether. These compounds can be brought into contact with a catalyst in the reactor to yield target compounds such as ethylene and propylene.

[0079] The raw materials may include saturated aliphatic hydrocarbons such as paraffin, olefins with 7 or more carbon atoms, and oxygen-containing compounds with 7 or more carbon atoms. These saturated aliphatic hydrocarbons, olefins with 7 or more carbon atoms, and oxygen-containing compounds with 7 or more carbon atoms can be converted to target compounds such as propylene by contact with a catalyst, similar to ethylene and ethanol, through a combination of dehydrogenation and dehydration reactions. However, they are less reactive than the aforementioned olefins with 4 to 6 carbon atoms and oxygen-containing compounds with 1 to 6 carbon atoms other than ethanol.

[0080] Furthermore, the raw materials may include a reaction gas containing olefins with 3 or more carbon atoms obtained from the ethanol conversion process, from which all or part of the olefins with 4 or more carbon atoms have been separated by a separation process. In this way, by using a so-called recycling reaction system, the effective utilization of olefin raw materials can be achieved.

[0081] In addition to the raw materials described above, which can be converted into target compounds such as propylene through an ethanol conversion process, the raw materials may also include inert gases such as nitrogen. Furthermore, the raw materials may include hydrogen and methane as diluent gases, but hydrogen dilution is preferable. Hydrogen is sometimes used to suppress the coking degradation of the catalyst.

[0082] In the ethanol conversion process, the raw materials may contain water. Since the ethylene and ethanol contained in the mixed raw materials are produced by various manufacturing methods, they may contain "water generated in the manufacturing process." Here, "water generated in the manufacturing process" refers to water that is generated during the manufacturing process of ethylene and / or ethanol and has not been removed.

[0083] In the ethanol conversion process, water vapor can be added to the mixed raw materials in addition to the water generated during the manufacturing process. Water vapor has the effect of further suppressing catalyst coking degradation by lowering the partial pressure of olefins in the reactor and improving the yield of lower olefins. On the other hand, since water vapor may promote the dealuminization of zeolite, it is preferable not to add water vapor to the mixed raw materials in addition to the water generated during the manufacturing process.

[0084] (Adiabatic reactor) In the ethanol conversion process, the reactor is not particularly limited, but an adiabatic reactor is preferred because it consumes less energy. For information on adiabatic reactors, refer to the description in Adiabatic Fixed-Bed Reactors (Elsevier, 2014, Ch.1, P.4, L.5~24 ISBN:978-0-12-801306-9). Examples of adiabatic reactors include fixed-bed adiabatic reactors, moving-bed adiabatic reactors, and fluidized-bed adiabatic reactors, but a fixed-bed adiabatic reactor is preferred for the method of this embodiment. Among fixed-bed adiabatic reactors, a fixed-bed single-stage adiabatic reactor with only one fixed catalyst bed is more preferred. As carbonaceous material (coke) accumulates on the catalyst during the reaction, a multi-column switching type fixed-bed single-stage adiabatic reactor that can burn off this carbonaceous material while continuing the reaction is more preferred.

[0085] Figure 3 is a schematic diagram of a fixed-bed, single-stage insulated reactor. The fixed-bed, single-stage insulated reactor 211 comprises a reaction casing 212 with an insulating material 216 on its outer periphery, a catalyst bed 213, a reactor inlet 214, and a reactor outlet 215. The insulating material 216 on the outer periphery of the reaction casing 212 prevents heat from escaping from inside the reactor to the outside. In the manufacturing method according to this embodiment, the temperature inside the reactor can be controlled by the heat generated and absorbed by the reaction.

[0086] The catalyst bed 213 is filled with a catalyst, which will be described later. A first sheathed thermocouple 217 is provided just before contact with the catalyst bed inlet 219a of the catalyst bed 213. A second sheathed thermocouple 218 is provided immediately after passing through the catalyst bed outlet 219b of the catalyst bed 213. These thermocouples are used to measure the temperature of the mixed raw materials just before contact with the catalyst bed inlet 219a and the temperature of the reaction gas immediately after passing through the catalyst bed outlet 219b. The catalyst bed 213 may be a multi-stage type, but it is preferable to have a single-stage type as shown in Figure 3.

[0087] In the fixed-bed, single-stage insulated reactor 211, the mixed raw materials are introduced from the reactor inlet 214, brought into contact with the catalyst bed 213, and the reaction gas is removed from the reactor outlet 215.

[0088] The reaction temperature in the ethanol conversion process is preferably 300 to 600°C, more preferably 450 to 590°C, and even more preferably 500 to 580°C, from the viewpoint of increasing reactivity while further suppressing coking deterioration. In this specification, the reaction temperature is calculated using the formula: [catalyst bed inlet temperature + catalyst bed outlet temperature] / 2. The catalyst bed inlet temperature is the temperature of the mixed raw materials immediately before the raw material fluid comes into contact with the catalyst bed packed in the adiabatic reactor. The catalyst bed outlet temperature is the temperature of the reaction gas immediately after it passes through the catalyst bed. The temperatures of the mixed raw materials and reaction gas referred to here are temperatures between 0d and 0.8d, where 0 is the center of the reactor and d is the distance from the center of the reactor to the inner wall of the reactor, in a plane perpendicular to the direction of fluid flow.

[0089] The raw material supply rate in the ethanol conversion process is preferably 0.1 to 1000 hours, based on the space velocity (WHSV) of the catalyst. -1 And more preferably 0.1 to 500 hours. -1 And more preferably 0.5 to 100 hours -1 In the ethanol conversion process, WHSV is calculated by first converting ethanol to ethylene, as shown in the formula below.

[0090] WHSV(hr -1 )=Material supply mass flow rate (kg / hr) / catalyst amount (kg)

[0091] Raw material supply mass flow rate (kg / hr) = Ethylene flow rate (kg / hr) + Ethylene-equivalent ethanol flow rate (kg / hr) + Olefin flow rate (4-6 carbon atoms) (kg / hr) + Oxygen-containing compound flow rate (1-6 carbon atoms) other than ethanol (kg / hr)

[0092] Ethylene-equivalent ethanol flow rate (kg / hr) = Ethanol flow rate (kg / hr) × Ethylene molecular weight (g / mol) / Ethanol molecular weight (g / mol)

[0093] (catalyst) The catalyst used in the ethanol conversion process is a solid catalyst that exhibits catalytic activity in converting olefins and ethanol into target compounds such as propylene. Zeolite-containing catalysts are preferred as such catalysts due to their superior thermal durability and propylene selectivity. A common problem in conventional olefin production using zeolites is coking degradation, where heavy carbonaceous material (coke) accumulates inside the zeolite pores due to reaction with hydrocarbons, leading to catalyst deactivation. While it is preferable to burn and remove the coke in an oxygen-containing atmosphere to regenerate catalyst performance, this coke combustion leads to structural breakdown of the zeolite, inducing permanent catalyst degradation that is difficult to regenerate. The ethanol conversion process suppresses coke formation, making it easier to maintain activity even when using zeolite-containing catalysts.

[0094] The catalyst is replaced periodically to maintain a constant composition of the ethanol conversion fraction. The period from the start of catalyst use to catalyst replacement is preferably 0.25 to 4.0 years, more preferably 0.50 to 3.5 years, and even more preferably 0.75 to 2.5 years, as this provides excellent production efficiency for light olefins.

[0095] Zeolite-containing catalyst A zeolite-containing catalyst is a catalyst powder or molded body containing zeolite as an active species. In the ethanol conversion process, it is preferable to use a so-called intermediate-pore zeolite, which has a pore size of 5 to 6 Å, as the zeolite in the above-mentioned zeolite-containing catalyst. An intermediate-pore zeolite means "a zeolite whose pore size range is intermediate between the pore size of small-pore zeolites represented by type A zeolites and the pore size of large-pore zeolites represented by mordenite-type zeolites, type X zeolites, and type Y zeolites." An intermediate-pore zeolite has a so-called 10-membered oxygen ring in its crystal structure.

[0096] Examples of zeolites with intermediate pore size include MFI type zeolites such as ZSM-5, ZSM-8, ZSM-11, ZSM-12, ZSM-21, ZSM-23, ZSM-35, ZSM-38, LZ-105, FZ-1, TS-1, and silicon. Among these, MFI type zeolites are preferred, and ZSM-5 is more preferred. In addition, zeolites similar to ZSM-5 and ZSM-11 described in Stud. Surf. Sci. Catal. 1987, 33, 167-215 can be used. Among these, MFI type zeolites are preferred, and ZSM-5 is more preferred, from the viewpoint of excellent catalytic performance (catalytic activity and durability against coking).

[0097] The silica / alumina (SiO2 / Al2O3) molar ratio of the zeolite contained in the zeolite-containing catalyst of this embodiment can be appropriately selected, but from the viewpoint of superior catalytic activity and propylene selectivity, it is preferably 20 to 2000, more preferably 100 to 1500, even more preferably 300 to 1200, and even more preferably 800 to 1200, from the viewpoint of further improving the durability of the catalyst. The silica / alumina (SiO2 / Al2O3) molar ratio of the zeolite contained in the zeolite-containing catalyst may also be 20 to 400 or 100 to 300. The silica / alumina molar ratio of the zeolite can be measured by known methods, for example, by completely dissolving the zeolite in an alkaline aqueous solution and analyzing the resulting solution by plasma emission spectrometry or the like.

[0098] There are no particular restrictions on the method of synthesizing the zeolite in this embodiment, but it can be produced by optimizing various conditions of conventionally known hydrothermal synthesis methods for MFI-type zeolites. Generally, means of efficiently obtaining MFI-type zeolites by hydrothermal synthesis include methods using appropriate organic structure-regulating agents (SDAs), methods of adding hydrothermally synthesized MFI zeolites as seed crystals for hydrothermal synthesis, and methods of adding them as seed slurry in the crystalline stage for hydrothermal synthesis. Examples of organic structure-regulating agents (SDAs) used here include ammonium salts, urea compounds, amines, and alcohols. It is also known that inorganic cations and anions, not just organic SDAs, are involved in the structure, and zeolite synthesis depends on the combined function of each component. In the hydrothermal synthesis method of MFI-type zeolites described above, a suitable catalyst can be obtained by appropriately optimizing the raw material composition, such as the type of raw materials and additives (SDAs), the amount of additives, pH, silica / alumina molar ratio, medium, and the abundance ratio of cations and anions, as well as synthesis conditions such as synthesis temperature and synthesis time.

[0099] Specifically, examples include the synthesis method using the seed slurry described in Japanese Patent Publication No. 5426983, and the method exemplified in "The Hydrothermal Synthesis of Zeolites" (Chemical Reviews, 2003, 103, 663-702).

[0100] Furthermore, commercially available zeolites can also be used, as long as they possess the specific physical properties and composition described above.

[0101] In this embodiment, the zeolite-containing catalyst preferably contains phosphorus or silver.

[0102] Phosphorus elements can take the form of phosphorus polymers (e.g., polyphosphate), phosphorus oxides (e.g., P2O5), or compounds in which phosphorus is added to the aluminum in the zeolite. Multiple forms of these may also be included. When the zeolite contains aluminum, the phosphorus element has the effect of further suppressing the dealuminization of the zeolite and, in some cases, improving the propylene yield. In particular, in applications exposed to high-temperature steam atmospheres, the properties of zeolite-containing catalysts are easily altered by dealuminization, so the effect of suppressing dealuminization is further enhanced.

[0103] The phosphorus content in the zeolite-containing catalyst is preferably 0.001 to 2.0% by mass relative to the total mass of the catalyst, and more preferably 0.01 to 1.0% by mass from the viewpoint of superior effect in suppressing dealuminization.

[0104] In this embodiment, the phosphorus content in the catalyst is shown as a value measured using an X-ray fluorescence analyzer. The phosphorus content can be measured using a commercially available X-ray fluorescence analyzer under normal conditions according to the instruction manual. For example, when using a Rigaku product, product name "RIX3000", the measurement conditions can be set to use P-Kα rays, tube voltage of 50kV, and tube current of 50mA.

[0105] In this embodiment, phosphoric acid and / or phosphates (hereinafter also referred to as "phosphorus raw material") are used as the raw material for the phosphorus element contained in the zeolite-containing catalyst. Phosphates are more preferred as the phosphorus raw material, and among phosphates, compounds that exhibit a solubility of 1 g or more in 100 g of water at 25°C are even more preferred.

[0106] Examples of phosphoric acid include phosphoric acid and pyrophosphate. Examples of phosphate salts include ammonium phosphate, diammonium hydrogen phosphate, ammonium dihydrogen phosphate, sodium ammonium hydrogen phosphate, potassium hydrogen phosphate, aluminum hydrogen phosphate, sodium phosphate, and potassium phosphate. Among these, ammonium phosphate salts with relatively high solubility in water are preferred, and more preferably, at least one selected from the group consisting of ammonium phosphate, diammonium hydrogen phosphate, and ammonium dihydrogen phosphate. These may be used individually or in combination of two or more.

[0107] One form of the element silver is, for example, silver ions. The element silver has the effect of improving the water and heat resistance of zeolites by controlling the acid sites of the zeolite.

[0108] The silver content in the zeolite-containing catalyst is preferably 0.01 to 2.0% by mass relative to the total mass of the catalyst, and more preferably 0.05 to 2.0% by mass from the viewpoint of superior improvement in hydrothermal resistance per unit content.

[0109] In this embodiment, the silver content in the catalyst is shown as a value measured using an X-ray fluorescence analyzer. The silver content can be measured using a commercially available X-ray fluorescence analyzer under normal conditions according to the instruction manual. For example, when using a Rigaku product, product name "RIX3000", the measurement conditions can be set to use P-Kα rays, tube voltage of 50kV, and tube current of 50mA.

[0110] In this embodiment, silver nitrate is used as a raw material for the silver element contained in the zeolite-containing catalyst. A zeolite-containing catalyst containing silver element can be obtained by ion exchange with silver nitrate using a zeolite-containing catalyst containing sodium as a countercation, and then sintering the mixture. Ion exchange between sodium, which is the countercation in the zeolite, and silver nitrate can be carried out by immersing the zeolite or zeolite-containing catalyst in an aqueous solution of silver nitrate and then washing it with water. At this time, the ion exchange rate can be improved by performing the immersion and washing multiple times. Alternatively, a zeolite-containing catalyst containing silver element can also be obtained by treating proton-type or ammonium-type zeolite with silver nitrate.

[0111] The zeolite-containing catalyst of this embodiment can be manufactured by molding, for example, the following method using a zeolite having the specific physical properties and composition described above. The molding method is not particularly limited, and general methods can be used. Specifically, methods include compression molding of the catalyst component, extrusion molding, and spray-drying molding, which is optimal for fluidized bed reaction systems.

[0112] Furthermore, a binder can be used for molding. The binder is not particularly limited, and for example, silica, alumina, and kaolin can be used individually or in combination. Commercially available binders can be used. The zeolite / binder mass ratio is preferably in the range of 10 / 90 to 90 / 10, and more preferably in the range of 20 / 80 to 80 / 20. From the viewpoint of further suppressing caulking, a silica binder is preferred.

[0113] In the ethanol conversion process, a pretreatment step may be performed on the zeolite-containing catalyst before contacting it with the raw material. A preferred pretreatment step is to heat-treat the catalyst at a temperature of 300°C or higher in the presence of water vapor. Pretreatment tends to more significantly suppress catalyst degradation and improve selectivity. In the above method, it is preferable to treat the catalyst at a temperature of 300°C to 900°C, with an atmosphere that is not particularly limited, but by circulating a mixed gas of air or an inert gas such as nitrogen and steam (water vapor), and under conditions of a water vapor partial pressure of 0.01 atmospheres or higher. A more preferable heat treatment temperature is between 400°C and 700°C. Furthermore, the pretreatment step can be performed using a reactor for ethanol conversion.

[0114] (Product: Ethanol conversion fraction containing ethylene and propylene) In the ethanol conversion process, an ethanol conversion fraction containing ethylene and propylene is obtained by contacting the raw materials with a catalyst. The ethanol conversion fraction may contain hydrogen, aliphatic hydrocarbons having 1 to 3 carbon atoms, aliphatic hydrocarbons having 4 to 8 carbon atoms, aromatic compounds, and hydrocarbons having 9 or more carbon atoms.

[0115] From the viewpoint of achieving superior production efficiency of the target compound, the total content of ethylene and propylene in the ethanol conversion fraction is preferably 15% by mass or more, more preferably 20% by mass or more, and even more preferably 25% by mass or more.

[0116] The mass ratio of propylene to ethylene in the ethanol conversion fraction (P / E) E The value is preferably 1.0 or less because it provides superior selectivity for light olefins. Furthermore, it is more preferably 0.20 to 1.0, and even more preferably 0.40 to 0.80, because it provides even better selectivity for propylene.

[0117] P / E ratio in ethanol conversion fraction E This fluctuates with catalyst degradation. In order to maintain the production volume of light olefins, the P / E ratio at the start of catalyst use is E(0) P / E at a certain point in time E The difference with (t) is preferably 0.40 or less, more preferably 0.35 or less, and even more preferably 0.30 or less. Also, as the catalyst deteriorates, P / E E Since it decreases, equation (5): P / E E (0)-P / E E (t) ≤ 0.40 ···(5) It is preferable to update and / or control the catalyst to satisfy the following conditions.

[0118] <Purification process> The method for producing light olefins may include a purification step in which target compounds such as ethylene and propylene are separated from the ethanol conversion fraction.

[0119] In the purification process, the ethylene and propylene content after purification is C E1 However, it is preferable to purify the ethanol conversion fraction so that its ethylene and propylene content is higher than that of the naphtha decomposition fraction or fraction derived therefrom in the confluence process, thereby obtaining a purified ethanol conversion fraction.

[0120] (Third cooling process) In the purification process, it is preferable to have a third cooling step in which the ethanol conversion fraction is introduced into a third cooling tower 22 to obtain a cooled ethanol conversion fraction mainly containing olefins with 6 or fewer carbon atoms.

[0121] The ethanol conversion fraction obtained in reactor 21 is introduced into a third cooling tower 22. In the third cooling tower 22, the aforementioned third cooling process is carried out to obtain a cooled ethanol conversion fraction mainly containing olefins with 6 or fewer carbon atoms. In the third cooling tower 22, hydrocarbons with more than 6 carbon atoms and water are removed by cooling the ethanol conversion fraction.

[0122] In the third cooling tower 22, cooling is preferably performed by bringing water into contact with the ethanol conversion fraction. The pH of the water used in the third cooling tower 22 can be adjusted as appropriate to suppress corrosion of the equipment.

[0123] The temperature of the cooled ethanol-converted fraction after processing in the third cooling tower 22 is preferably 5 to 200°C, more preferably 10 to 100°C.

[0124] The method for producing light olefins according to this embodiment preferably includes a recycling step in which at least a portion of the cooled ethanol conversion fraction is introduced into the reactor 21 as part of the raw materials. By supplying the cooled ethanol conversion fraction to the reactor 21 in this way, it can be converted into ethylene or propylene.

[0125] <Compression and Separation Process> The method for producing light olefins according to this embodiment may include a compression separation step in which the cooled ethanol conversion fraction is pressurized by a compressor to obtain a light ethanol conversion fraction mainly containing olefins with 3 or fewer carbon atoms as a gas component, and a heavy ethanol conversion fraction mainly containing olefins with 4 or more carbon atoms as a liquid component.

[0126] The compression and separation process is as follows: A second compression step involves pressurizing the cooled ethanol conversion fraction using a compressor, The process may include a distillation step in which a light ethanol conversion fraction mainly containing olefins with 3 or fewer carbon atoms is obtained as a gaseous component by a distillation column, and a heavy ethanol conversion fraction mainly containing olefins with 4 or more carbon atoms is obtained as a liquid component.

[0127] Furthermore, the method for producing light olefins according to this embodiment preferably includes a recycling step in which at least a portion of the heavy ethanol conversion fraction is introduced into the reactor 21 as part of the raw materials. By supplying the heavy ethanol conversion fraction to the reactor 21 in this way, the olefins contained in the heavy ethanol conversion fraction are converted into ethylene or propylene, thereby improving the efficiency of producing light olefins from ethanol.

[0128] The compression separation process may involve liquefying a portion of the fraction by increasing the pressure with a compressor, and then processing this fraction with a gas-liquid separator to obtain a light ethanol conversion fraction mainly containing olefins with 3 or fewer carbon atoms as the gaseous component, and a heavy ethanol conversion fraction mainly containing olefins with 4 or more carbon atoms as the liquid component. By using a gas-liquid separator, energy consumption related to the compression separation process can be further reduced compared to using a distillation column.

[0129] Thus, when the ethanol conversion fraction, which has undergone a compression separation process using a gas-liquid separator, is combined in the subsequent consolidation process, it is combined with a fraction derived from naphtha cracking that has a high content of olefins with 3 carbon atoms, from which hydrocarbons with 4 or more carbon atoms have been removed. This reduces the content of hydrocarbons with 4 or more carbon atoms in the combined fraction and increases the proportion of ethylene and propylene. As a result, the processing energy in cryogenic separation can be further reduced.

[0130] Furthermore, the method for producing light olefins according to this embodiment preferably includes a recycling step in which at least a portion of the heavy ethanol conversion fraction obtained through a compression separation step by a gas-liquid separation device is introduced into the reactor 21 as part of the raw materials. By supplying the heavy ethanol conversion fraction to the reactor 21 in this way, the olefins contained in the heavy ethanol conversion fraction are converted to ethylene or propylene, thereby further improving the efficiency of producing light olefins from ethanol.

[0131] <Merge process> In the consolidation step, at least a portion of the naphtha decomposition fraction or a fraction derived therefrom is combined with at least a portion of the ethanol conversion fraction or a fraction derived therefrom to obtain a combined fraction.

[0132] "Naphtha cracking fraction" refers to the fraction obtained by the cracking process described above. "Fraction derived therefrom" refers to the fraction obtained by further purifying the naphtha cracking fraction. The naphtha cracking fraction may also be mixed with a hydrocarbon-containing gas to adjust its properties before purification.

[0133] "Ethanol conversion fraction" refers to the fraction obtained through the ethanol conversion process described above. "Fraction derived therefrom" refers to the fraction obtained by further purifying the ethanol conversion fraction.

[0134] <Light Olefins> According to the manufacturing method of this embodiment, a light olefin can be obtained. The light olefin is obtained by the cryogenic separation step described above. In the method for producing olefins according to this embodiment, the light olefin may be either ethylene or propylene, but propylene is preferred. Furthermore, according to the manufacturing method of this embodiment, biomass-derived propylene can also be produced by using biomass resources such as bioethanol as raw materials used in the ethanol conversion step. [Examples]

[0135] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the examples described below.

[0136] [Methods for measuring various physical properties] The methods for measuring various physical properties are as follows.

[0137] (Molar ratio of silica / alumina in zeolite in zeolite-containing catalyst, and phosphorus content) A solution was prepared by completely dissolving zeolite in a sodium hydroxide solution. The Si, Al, and P content in this solution was measured using a conventional method with an ICP (inductively coupled plasma) emission spectrometer (Rigaku, product name "JY138"), and the silica / alumina molar ratio was derived from the results. The measurement conditions were set as follows: high-frequency power: 1 kW, plasma gas: 13 L / min, sheath gas: 0.15 L / min, nebulizer gas: 0.25 L / min, Si measurement wavelength: 251.60 nm, Al measurement wavelength: 396.152 nm.

[0138] (Zeolite structural type) The structural type of zeolite in the zeolite-containing catalyst was identified by measuring the X-ray diffraction pattern of the zeolite using an X-ray analyzer (Rigaku, product name "RINT") and referring to the diffraction patterns of known zeolites. The measurement conditions were as follows. Cu cathode Tube voltage: 40kV Bulb current: 30mA Scan speed: 1 deg / min

[0139] [Method for preparing zeolite-containing catalysts] Clay obtained from 70 parts by mass of proton-type ZSM-5 (silica / alumina molar ratio 980), a zeolite with an intermediate pore size, and 30 parts by mass of silica (moisture content adjusted using colloidal silica and fumed silica) was kneaded and then extruded to obtain extruded bodies with a diameter of 2.1 mm and a length of 4-6 mm. The obtained bodies were fired at 600°C for 5 hours and then washed with 0.1 M nitric acid and water. Next, diammonium hydrogen phosphate was impregnated and supported so that the molar ratio of Al in the zeolite to the added P was 0.70 (P / Al), and the catalyst containing zeolite was fired at 600°C for 2 hours to obtain a zeolite-containing catalyst. At this time, the phosphorus content relative to the total zeolite-containing catalyst was 0.04% by mass.

[0140] [Method for converting to ethanol] (raw materials) In the examples and comparative examples, raw materials mainly consisting of ethanol, ethylene, and olefins having 4 to 6 carbon atoms were used for ethanol conversion.

[0141] (temperature measurement) The temperatures at the catalyst bed inlet and outlet were measured using thermocouples inserted from outside the reactor. Specifically, as shown in Figure 3, in a plane perpendicular to the fluid flow direction, with the reactor center set to 0 and the distance from the reactor center to the reactor inner wall surface being d, the temperature was measured between 0.5d and 0.6d. The effect of heat dissipation due to the insertion of these thermocouples was negligibly small.

[0142] (Ethanol conversion reaction) In the examples and comparative examples, the temperature of the raw materials was changed so that the reaction temperature was 510°C, and the ethanol conversion reaction was carried out by introducing the raw materials into a fixed-bed adiabatic reactor filled with a zeolite-containing catalyst. In the ethanol conversion reaction, at least one reactor was used for the reaction and at least one for catalyst regeneration. Light olefins were continuously produced by switching between the reaction and catalyst regeneration every 48 hours. The catalysts packed in each reactor were replaced according to their degradation status.

[0143] (Gas analysis of ethanol conversion fraction) Equipment: Shimadzu GC-2030 Column: Custom capillary column SPB-1 manufactured by SUPELCO, USA (inner diameter 0.25 mm, length 60 m, film thickness 3.0 μm) Sample gas volume: 1 mL (Sampling line should be kept warm at 200°C to 300°C) Temperature increase program: Maintain a temperature of 40°C for 12 minutes, then increase the temperature to 200°C at a rate of 5°C / minute, and maintain that temperature for 22 minutes. Split ratio: 200:1 Carrier gas (nitrogen) flow rate: 120 mL / min FID detector: Air supply pressure 50kPa (approx. 500mL / min), hydrogen supply pressure 60kPa (approx. 50mL / min) Measurement method: A TCD detector and an FID detector were connected in series. Composition analysis was performed based on the data detected by the TCD detector for hydrogen and the data detected by the FID detector for oxygen-containing substances such as hydrocarbons and ethanol. The concentration of the target compound in the reaction gas was determined using a calibration curve method, and the mass produced per unit time by the reaction was calculated.

[0144] [Methods for naphtha decomposition] In the examples and comparative examples, naphtha decomposition gas was obtained by co-feeding naphtha and diluted steam into a heated tubular reaction tube. The obtained naphtha decomposition fraction was analyzed in the same manner as the ethanol conversion method. The composition of the naphtha is shown in Table 1.

[0145] [Table 1]

[0146] [Reference example 1] Naphtha feedstock (S / N ratio, steam-naphtha ratio: 0.35) containing naphtha and diluted steam at a mass ratio of 0.35 to naphtha is processed at a total pressure of 2.09 kg / cm² in the decomposition furnace. 2 The naphtha was introduced into the naphtha cracking furnace under these operating conditions. At this time, the outlet temperature of the cracking furnace was changed from 786°C to 846°C, and the ethylene concentration in the naphtha cracked fraction and P / E ratio were changed. N We observed the changes in P / E. The results are shown in Figures 4 and 5. As shown in these figures, the ethylene concentration (wt%) increases with increasing decomposition furnace outlet temperature (COT, °C), while P / E N It decreased.

[0147] [Reference example 2] The naphtha feedstock, including naphtha and diluted steam, is processed under a total pressure of 2.09 kg / cm² in the cracking furnace. 2 The ethylene concentration and P / E ratio in the naphtha cracking fraction were changed from 0.1 to 1.0. N We observed the changes in P / E. The results are shown in Figures 6 and 7. As shown in these figures, with increasing S / N ratio, the ethylene concentration (wt%) increased, and P / E N It also increased.

[0148] [Reference example 3] Naphtha feedstock (S / N ratio, steam-naphtha ratio: 0.35) containing naphtha and diluted steam at a mass ratio of 0.35 to naphtha was introduced into a naphtha cracking furnace under operating conditions with a cracking furnace outlet temperature of 816°C. At this time, the total pressure inside the cracking furnace was 1.09 kg / cm². 2 From 4.09 kg / cm³ 2 The ethylene concentration and P / E ratio in the naphtha decomposition fraction were changed to the extent that the ethylene concentration and P / E ratio in the naphtha decomposition fraction were changed. N The changes were observed. The results are shown in Figures 8 and 9. As shown in these figures, the internal pressure of the decomposition furnace (kg / cm²) 2 As the ethylene concentration (wt%) increases, the P / E ratio decreases. N It also decreased.

[0149] [Comparative Example 1] Comparative Example 1 used a light olefin production facility consisting of two ethanol conversion reactors, a small naphtha cracking reactor A, a small naphtha cracking reactor B, and a large naphtha cracking reactor C. In Comparative Example 1, the operating conditions of the cracking reactors were not changed throughout the 365 days.

[0150] (Ethanol conversion) In the ethanol conversion process, one of the two reactors was used for the reaction and the other for catalyst regeneration. Each reactor was operated by switching between reaction and catalyst regeneration every 48 hours to continuously produce light olefins. A raw material containing 23.6% by mass of ethanol, 15.1% by mass of ethylene, and 16.0% by mass of olefins with 4 to 6 carbon atoms was heated and supplied to a reactor packed with a zeolite-containing catalyst to achieve a WHSV of 3.8, thereby carrying out the ethanol conversion reaction and obtaining the ethanol conversion fraction. In addition to the above, the raw materials also contained paraffin, olefins with 7 or more carbon atoms, and water. During this process, the heating furnace was adjusted so that the temperature at the reactor outlet remained at 510°C throughout the 365 days. The production amounts of ethylene and propylene from the ethanol conversion are shown in Table 2. In the ethanol conversion process, as the zeolite-containing catalyst deteriorated with use, the amount of ethylene produced increased over time, while the amount of propylene produced decreased over time. The amount of ethylene produced at the start of the reaction was 20 tons / day.

[0151] (Naphtha cracking) Naphtha feedstock (S / N ratio, steam-naphtha ratio: 0.35) containing naphtha and diluted steam at a mass ratio of 0.35 to naphtha is processed under a decomposition furnace pressure of 2.09 kg / cm². 2 The naphtha was then introduced into small naphtha crackers A, B, and C, and a naphtha cracker was opened at an outlet temperature of 816°C to obtain naphtha cracked fractions. Each cracker produced ethylene at rates of 20 tons / day, 20 tons / day, and 40 tons / day, respectively.

[0152] (Separation and purification of light olefins) The reaction gases obtained from ethanol conversion and naphtha cracking were combined, and the resulting mixed gas was introduced into a cryogenic separation process to obtain ethylene and propylene. The production amounts of the light olefins obtained are shown in Table 2. In Comparative Example 1, after 365 days, ethylene production increased by 6.6%, and propylene production decreased by 3.5%. In the cryogenic separation process, a significant amount of energy was consumed to liquefy the light olefins. At this time, fluctuations in the production volume made it difficult to pressurize, liquefy, and distill the light olefins, resulting in a significant decrease in purification efficiency.

[0153] [Table 2]

[0154] [Example 1] In Example 1, a light olefin production facility consisting of two ethanol conversion reactors, a small naphtha cracking furnace A, a small naphtha cracking furnace B, and a large naphtha cracking furnace C was used. In Example 1, the outlet temperature of cracking furnace C was controlled in accordance with the catalyst degradation during ethanol conversion.

[0155] (Ethanol conversion) In the ethanol conversion process, one of the two reactors was used for the reaction and the other for catalyst regeneration. Each reactor was operated by switching between reaction and catalyst regeneration every 48 hours to continuously produce light olefins. The catalysts in both reactors were replaced one year after the start of use. A raw material containing 23.6% by mass of ethanol, 15.1% by mass of ethylene, and 16.0% by mass of olefins with 4 to 6 carbon atoms was heated and supplied to a reactor packed with a zeolite-containing catalyst to achieve a WHSV of 3.8, thereby carrying out the ethanol conversion reaction and obtaining the ethanol conversion fraction. In addition to the above, the raw materials also contained paraffin, olefins with 7 or more carbon atoms, and water. During this process, the heating furnace was adjusted so that the temperature at the reactor outlet remained at 510°C throughout the 365 days. The production amounts of ethylene and propylene from the ethanol conversion are shown in Table 3. In the ethanol conversion process, as the zeolite-containing catalyst deteriorated with use, the amount of ethylene produced increased over time, while the amount of propylene produced decreased over time. The amount of ethylene produced at the start of the reaction was 20 tons / day.

[0156] (Naphtha cracking) Naphtha feedstock (S / N ratio, steam-naphtha ratio: 0.35) containing naphtha and diluted steam at a mass ratio of 0.35 to naphtha is processed under a decomposition furnace pressure of 2.09 kg / cm². 2 The naphtha was then introduced into small naphtha cracker A, small naphtha cracker B, and large naphtha cracker C under operating conditions with a cracking furnace outlet temperature of 816°C, and the production of naphtha cracked fractions was started. At the start of the reaction, each cracker produced ethylene at rates of 20 tons / day, 20 tons / day, and 40 tons / day, respectively. In large cracking reactor C, the P / E ratio of the ethanol conversion fraction E In accordance with the changes, the temperature at the decomposition reactor outlet was controlled at 90, 183, 270, and 365 days.

[0157] (Separation and purification of light olefins) The reaction gases obtained from ethanol conversion and naphtha cracking were combined, and the resulting mixed gas was introduced into a cryogenic separation process to obtain ethylene and propylene. The amount of light olefin produced is shown in Table 3. In Example 1, after 365 days, the amount of ethylene produced increased by 3.3%, and the amount of propylene produced increased by 1.1%. In Example 1, by controlling the conditions of the decomposition furnace, it was possible to suppress fluctuations in the amount of light olefin produced compared to Comparative Example 1.

[0158] [Table 3]

[0159] [Example 2] In Example 2, the procedure was the same as in Example 1, except that the outlet temperature of cracking furnace A, which produces less ethylene than cracking furnace C, was controlled to match the catalyst degradation during ethanol conversion. The operating conditions of each cracking furnace and the production amounts of ethylene and propylene are shown in Table 4.

[0160] Comparing Example 2 with Example 1, when controlling the production volume of light olefins using the smaller-scale cracking furnace A, the range of temperature changes was larger than when using the smaller-scale cracking furnace C. In other words, it was found that by controlling a larger-scale cracking furnace, the range of changes in operating conditions can be reduced, making the controlled operation of the naphtha cracking furnace easier.

[0161] [Table 4]

[0162] [Example 3] In Example 3, the procedure was the same as in Example 1, except that the outlet temperature of cracking furnace C was controlled so that [CR × Δ (cracking furnace parameter) - ER × [P / EE(0) - P / EE(t)]] was 0.050 or higher after 90 days. The operating conditions of each cracking furnace and the production amounts of ethylene and propylene are shown in Table 5.

[0163] In Example 3, although the increase in ethylene production was effectively suppressed, the amount of propylene produced after 90 days increased significantly by 5.7% compared to the start. It was found that in order to maintain a constant amount of ethylene and propylene production, it is preferable to control the operating conditions of the cracking furnace to satisfy equation (3).

[0164] [Table 5]

[0165] [Example 4] In Example 4, the procedure was the same as in Example 1, except that the steam naphtha ratio of cracking furnace C was controlled instead of the cracking furnace outlet temperature to match the catalyst degradation during ethanol conversion. The operating conditions of each cracking furnace and the production amounts of ethylene and propylene are shown in Table 6.

[0166] Comparing Example 4 with Example 1, it was found that when controlling the ethylene production amount by the steam naphtha ratio, the fluctuation in propylene production amount becomes large, exceeding 10%, and therefore it is preferable to adjust the decomposition furnace parameters by the decomposition furnace outlet temperature.

[0167] [Table 6]

[0168] [Example 5] In Example 5, the procedure was carried out in the same manner as in Example 1, except that the internal pressure of cracking furnace C was controlled instead of the outlet temperature of the cracking furnace to match the catalyst degradation during ethanol conversion. The operating conditions of each cracking furnace and the production amounts of ethylene and propylene are shown in Table 7.

[0169] Comparing Example 5 with Example 1, it was found that when the amount of ethylene produced is controlled by the pressure inside the decomposition furnace, the fluctuation in the amount of propylene produced becomes large, exceeding 10%. Therefore, it is preferable to adjust the decomposition furnace parameters by the outlet temperature of the decomposition furnace.

[0170] [Table 7]

[0171] [Example 6] In Example 6, the procedure was carried out in the same manner as in Example 1, except that the steam naphtha ratio was controlled in addition to the outlet temperature of cracking furnace C to match the catalyst degradation during ethanol conversion. The operating conditions of each cracking furnace and the production amounts of ethylene and propylene are shown in Table 8.

[0172] Comparing Example 6 with Example 1, it was found that by controlling the steam naphtha ratio in addition to the decomposition furnace outlet temperature, fluctuations in ethylene and propylene production can be further suppressed.

[0173] [Table 8] [Explanation of Symbols]

[0174] E...Ethanol conversion process, N...Naphtha cracking process, N1...Naphtha cracking, N2...Purification process of naphtha cracked fraction, N3...Cryogenic separation, 11...Cracking furnace, 12...First cooling tower, 13...Second cooling tower, 14...First compressor, 15...Soda washing tower, 16...Cryogenic separation equipment, 21...Reactor, 22...Third cooling tower, 23...Second compressor, 24...Distillation tower, 25...Condenser, 211...Fixed-bed single-stage insulated reactor, 212...Reaction enclosure, 213...Catalyst bed, 214...Reactor inlet, 215...Reactor outlet, 216...Insulation material, 217...First sheath thermocouple, 218...Second sheath thermocouple, 219a...Catalyst bed inlet, 219b...Catalyst bed outlet, d...Distance from the center of the reactor to the inner wall of the reactor.

Claims

1. The process involves introducing naphtha raw materials into a cracking furnace to obtain naphtha cracked fractions, and An ethanol conversion process involves introducing a raw material containing ethanol into a reactor and contacting it with a catalyst to obtain an ethanol conversion fraction containing ethylene and propylene, The process includes a consolidation step of combining at least a portion of the naphtha decomposition fraction or a fraction derived therefrom with at least a portion of the ethanol conversion fraction or a fraction derived therefrom to obtain a combined fraction, In the cracking process, the operating conditions of at least one of the cracking furnaces are given by Δ (cracking furnace parameter) in equation (1): Δ (cracking furnace parameter) = 0.0059×[COT(0)-COT(t)]-0.0726×[S / N(0)-S / N(t)]+0.0687×[P(0)-P(t)]...(1) (however, COT(t): Decomposition furnace outlet temperature at a certain point in time. COT(0): Decomposition furnace outlet temperature at the start of catalyst use. S / N(t): Steam naphtha ratio at a given point in time. S / N(0): Steam naphtha ratio at the start of catalyst use. P(t): Total pressure inside the decomposition reactor at a certain point in time. P(0): Total pressure inside the decomposition furnace at the start of catalyst use. (This represents...) The above Δ (decomposition reactor parameter) is given by equation (2): CR × Δ (decomposition reactor parameters) - ER × [P / E E (0) - P / E E (t)]≧0...(2) (however, P / E E (t): The mass ratio of propylene to ethylene in the ethanol conversion fraction at a certain point in time. P / E E (0): Mass ratio of propylene to ethylene in the ethanol conversion fraction at the start of catalyst use. ER: The mass ratio of ethylene production in the ethanol conversion process at the start of catalyst use to the total ethylene production. CR: The mass ratio of the amount of ethylene produced by the controlled cracking furnace at the start of catalyst use to the total amount of ethylene produced. (This represents...) A method for producing light olefins, controlled to satisfy the following conditions.

2. In the cracking process, the Δ (cracking furnace parameter) is given by equation (3): CR × Δ (decomposition reactor parameters) - ER × [P / E E (0) - P / E E (t)]≦0.050...(3) A method for producing a light olefin according to claim 1, which is controlled to satisfy the following conditions.

3. In the above-mentioned at least one decomposition furnace, the decomposition furnace outlet temperature at any point in time during the operation of the decomposition furnace is given by equation (4): CR×0.0059×[COT(0)-COT(t)]-ER×[P / E E (0)-P / E E (t)]≧0・・・(4) A method for producing a light olefin according to claim 1, controlled to satisfy the following conditions.

4. The method for producing a light olefin according to claim 1, wherein in the at least one decomposition furnace, the decomposition furnace outlet temperature at any point during the operation of the decomposition furnace is controlled to satisfy a range of 700 to 1000°C.

5. A method for producing a light olefin according to claim 1, wherein the mass ratio ER is 0.20 or more.

6. The ethanol conversion fraction is given by formula (5): P / E E (0)-P / E E (t)≦0.40・・・(5) A method for producing a light olefin according to claim 1, wherein the catalyst is updated to satisfy the condition.

7. The method for producing a light olefin according to claim 1, wherein the catalyst is a zeolite-containing catalyst.

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