Method for producing ethylene and propylene

Abstract

The present invention addresses the problem of providing a method which is for producing ethylene and propylene and with which it is possible to significantly reduce energy consumption in a rectification step.　The method for producing ethylene and propylene includes: a reaction step for bringing a raw material containing ethanol into contact with a catalyst to obtain a product containing ethylene and propylene; a gas-liquid separation step of separating the product obtained in the reaction step into a gas component containing ethylene and propylene and a liquid component containing acetone; a gas component purification step for purifying the gas component obtained in the gas-liquid separation step to obtain a gas component containing ethylene and propylene; and a naphtha cracker supply step for supplying the gas component obtained in the gas component purification step to a naphtha cracker to obtain ethylene and propylene.

Description

Method for producing ethylene and propylene

[0001] The present invention relates to a method for producing ethylene and propylene using ethanol as a raw material.

[0002] Ethylene and propylene, which are lower olefins, are key raw materials in the chemical industry and have conventionally been produced from petroleum as a raw material by, for example, petroleum refining, naphtha cracking, etc.

[0003] Recently, due to growing interest in climate change issues and increased awareness of environmental conservation, there is a demand for technologies for producing lower olefins from raw materials with low environmental impact, sustainable raw materials, etc. Specifically, for example, technologies for producing lower olefins using methanol or ethanol produced from biomass raw materials, waste, etc. as raw materials have been attracting attention.

[0004] As a technique for producing such lower olefins, for example, Patent Documents 1 and 2 disclose a method for producing propylene from ethanol using a zirconium oxide catalyst, and Patent Documents 3 and 4 disclose a method for producing ethylene and propylene from ethanol using a zirconium oxide catalyst.

[0005] JP 2012-254447 A JP 2023-96890 A JP 2016-150932 A WO 2022 / 168695

[0006] However, in conventional methods for producing ethylene and propylene, a large amount of energy is required in the rectification step of ethylene and propylene, and the amount of carbon dioxide generated increases with the increase in the energy consumption, which is problematic from the viewpoint of environmental load. Therefore, in methods for producing ethylene and propylene, a reduction in the energy consumption in the rectification step is desired.

[0007] Under these circumstances, an object of the present invention is to provide a method for producing ethylene and propylene, which can relatively reduce the amount of energy consumed in the rectification step.

[0008] The method for producing ethylene and propylene according to the present invention comprises: a reaction step (1) of contacting a raw material (1a) containing ethanol with a catalyst to obtain a product (1b) containing ethylene and propylene; a gas-liquid separation step (2) of separating the product (1b) obtained in the reaction step (1) into a gas component (2a) containing ethylene and propylene and a liquid component (2b) containing acetone; a gas component purification step (3) of purifying the gas component (2a) obtained in the gas-liquid separation step (2) to obtain a gas component (3a) containing ethylene and propylene; and a naphtha cracker supply step (4) of supplying the gas component (3a) obtained in the gas component purification step (3) to a naphtha cracker to obtain ethylene and propylene.

[0009] According to the present invention, it is possible to provide a method for producing ethylene and propylene, which can relatively reduce the amount of energy consumed in the rectification step.

[0010] FIG. 1 is a process flow diagram showing a method for producing ethylene and propylene according to the present embodiment. FIG. 2 is a process flow diagram showing one aspect of a method for producing ethylene and propylene according to the present embodiment. FIG. 3 is a process flow diagram showing a method for producing ethylene and propylene according to a first aspect of the present embodiment. FIG. 4 is a process flow diagram showing a method for producing ethylene and propylene according to a second aspect of the present embodiment. FIG. 5 is a process flow diagram showing a method for producing ethylene and propylene according to a third aspect of the present embodiment. FIG. 6 is a process flow diagram showing a method for producing ethylene and propylene according to a fourth aspect of the present embodiment. FIG. 7 is a process flow diagram showing an example of a method for producing ethylene and propylene according to the present embodiment. FIG. 8 is a process flow diagram showing an example of a method for producing ethylene and propylene according to the present embodiment. FIG. 9 is a process flow diagram showing an example of a method for producing ethylene and propylene according to the present embodiment. FIG. 10 is a process flow diagram showing an example of a method for producing ethylene and propylene according to the present embodiment. FIG. 11 is a process flow diagram showing an example of a method for producing ethylene and propylene according to the present embodiment. FIG. 1 is a schematic diagram showing the configuration of a naphtha cracker in this embodiment.

[0011] Hereinafter, a method for producing ethylene and propylene according to an embodiment of the present invention will be described. Fig. 1 is a process flow diagram showing a method for producing ethylene and propylene according to this embodiment. As shown in Fig. 1, the method for producing ethylene and propylene according to this embodiment includes a reaction step (1), a gas-liquid separation step (2), a gas component purification step (3), and a naphtha cracker supply step (4).

[0012] [Reaction Step (1)] The method for producing ethylene and propylene according to this embodiment includes a reaction step (1) in which a raw material (1a) containing ethanol is contacted with a catalyst to obtain a product (1b) containing ethylene and propylene.

[0013] The ethanol contained in the raw material (1a) is not particularly limited, and examples thereof include biomass-derived ethanol, ethanol produced from carbon dioxide and hydrogen as raw materials, ethanol produced by the hydration reaction of ethylene, etc. These ethanols can be used alone or in combination of two or more.

[0014] Examples of carbon oxides that can be used as raw materials for ethanol include carbon oxides produced by decomposing biomass, carbon oxides produced from fossil raw materials, carbon oxides generated in the process of using fossil resources as energy, carbon oxides generated in the process of manufacturing steel or chemical products, carbon oxides produced using plastics as raw materials, and carbon dioxide recovered from the air. These carbon oxides can be used alone or in combination of two or more. Examples of hydrogen that can be used as raw materials for ethanol include hydrogen derived from fossil raw materials and hydrogen produced by decomposing ammonia or electrolyzing water.

[0015] The raw material (1a) may further contain at least one compound selected from the group of oxygen-containing compounds consisting of water, acetone, acetaldehyde, and isopropanol.

[0016] The raw material (1a) may contain water. The molar ratio of water to ethanol in the raw material (1a) (water (mol) / ethanol (mol)) is preferably 0.1 or more, more preferably 0.2 or more, and even more preferably 0.3 or more. The molar ratio of water to ethanol in the raw material (1a) is preferably 10 or less, more preferably 8 or less, and even more preferably 5 or less.

[0017] The catalyst may be any catalyst capable of synthesizing ethylene and propylene from ethanol, such as a zirconium oxide catalyst, an indium oxide catalyst, a cerium oxide catalyst, an aluminum oxide catalyst, or a zeolite catalyst. The catalyst is preferably a zirconium oxide catalyst, and more preferably a zirconium oxide catalyst further containing at least one element (M) selected from the group consisting of metals of Group 1 and Group 2 elements of the IUPAC Periodic Table of the Elements (2022), scandium, yttrium, cerium, titanium, vanadium, chromium, copper, silver, gallium, germanium, manganese, lanthanum, neodymium, and tin. The element (M) is preferably at least one element selected from the group consisting of lithium, sodium, potassium, magnesium, calcium, strontium, barium, scandium, yttrium, and cerium, more preferably at least one of calcium and yttrium, and even more preferably calcium. The element (M) may be contained in the zirconium oxide catalyst as a simple element, or as an oxide, hydroxide, salt, or alkoxide of the element. Examples of the salt include inorganic salts such as nitrates, sulfates, phosphates, hydrochlorides, and carbonates, and organic salts such as carboxylates, sulfonates, and organic phosphates.

[0018] The content of the element (M) in the catalyst is preferably more than 0 mass % and not more than 50 mass %, with the total of zirconium oxide and the element (M) being 100 mass %.

[0019] As the catalyst, for example, catalysts described in JP 2012-120978 A, JP 2012-136516 A, JP 2013-252495 A, JP 2013-254447 A, JP 2016-150932 A, WO 2022 / 168695, WO 2022 / 226371, and JP 2023-96890 can be used.

[0020] The reaction step (1) may be carried out using a reactor. Examples of reactors that can be used include fixed-bed reactors, moving-bed reactors, fluidized-bed reactors, batch reactors, and semi-batch reactors. The reactor may be an adiabatic reactor, an isothermal reactor, or a heat exchange reactor. The reactor may be a single-stage reactor or a multi-stage reactor equipped with a plurality of reactors. When the reactor is a multi-stage reactor, a heating device may be installed between each reactor. The reactor is preferably an adiabatic reactor such as a fixed-bed adiabatic reactor, a moving-bed adiabatic reactor, or a fluidized-bed adiabatic reactor, and more preferably a fixed-bed adiabatic reactor.

[0021] In the method for contacting the raw material (1a) with the catalyst, it is sufficient that the raw material (1a) be brought into contact with the catalyst in a gaseous or liquid state. From the viewpoint of further increasing the yield of ethylene and propylene in the product (1b), the method for contacting the raw material (1a) with the catalyst is preferably a method in which the raw material (1a) gasified by heating is supplied to a reactor pre-filled with a catalyst, and the gasified raw material (1a) is brought into contact with the catalyst. The gasified raw material (1a) may be supplied to the reactor in combination with other gas components. Examples of other gas components include nitrogen, hydrogen, carbon monoxide, and carbon dioxide.

[0022] The reaction temperature in the reaction step (1) is preferably 270°C to 700°C, more preferably 300°C to 650°C, and even more preferably 350°C to 550°C. When a reactor is used in the reaction step (1), the reaction temperature may be the temperature of the steam containing the raw material (1a) or the catalyst inside the reactor. The reactor may be equipped with a thermometer inside the reactor for measuring the temperature of the steam or the catalyst inside the reactor.

[0023] The reaction pressure in the reaction step (1) is preferably 10 kPaA to 10,000 kPaA, more preferably 100 kPaA to 5,000 kPaA.

[0024] (Raw Material Treatment Step) From the viewpoint of suppressing side reactions, the method for producing ethylene and propylene according to this embodiment may include a raw material treatment step in which the raw material (1a) is brought into contact with an acid adsorbent before being supplied to the reaction step (1). Examples of the acid adsorbent include (a) microporous aluminosilicate, (b) macroporous resin grafted with an acid group (e.g., sulfonic acid), (c) strongly acidic ion exchange resin, (d) silica impregnated with an acid (e.g., phosphoric acid, sulfuric acid), (e) activated carbon, (f) activated alumina, (g) clay, (h) molecular sieve, and (i) crystalline microporous aluminophosphate.

[0025] [Gas-Liquid Separation Step (2)] The method for producing ethylene and propylene according to this embodiment includes a gas-liquid separation step (2) for separating the product (1b) obtained in the reaction step (1) into a gas component (2a) containing ethylene and propylene and a liquid component (2b) containing acetone. The gas-liquid separation step (2) may be any method capable of separating most of the ethylene and propylene contained in the product (1b) into a gas phase.

[0026] In the gas-liquid separation step (2), for example, the product (1b) is cooled by a known cooling method using a tubular heat exchanger, an air fin cooler, or the like, and then separated into a gas component (2a) containing ethylene and propylene and a liquid component (2b) containing acetone using a packed tower. For example, a countercurrent packed tower or the like is used as the packed tower. The gas component (2a) and the liquid component (2b) are supplied to the bottom of the packed tower. An absorbing fluid (e.g., water, etc.) is added dropwise from the top of the packed tower. The gas component (2a) rises in contact with the absorbing fluid in the packed tower and is discharged from the top. The liquid component (2b) containing the absorbing fluid is extracted from the bottom of the packed tower. Furthermore, the method for separating the majority of ethylene and propylene contained in the product (1b) into a gas phase and the majority of acetone into a liquid phase may be a method in which the high-temperature gaseous product (1b) is supplied to a packed tower, and, in the packed tower, the acetone, for example, is cooled, liquefied, absorbed, and separated by the absorbing fluid.

[0027] Fig. 2 is a process flow diagram showing one embodiment of the method for producing ethylene and propylene according to this embodiment. As shown in Fig. 2, in one embodiment of the method for producing ethylene and propylene according to this embodiment, the gas-liquid separation step (2) may include an oil-water separation step (2-1) in which a water-soluble liquid component (2c) and a water-insoluble liquid component (2d) are separated from the liquid component (2b) obtained in the gas-liquid separation step (2). Examples of methods for separating the water-soluble liquid component (2c) and the water-insoluble liquid component (2d) from the liquid component (2b) include a method in which the mixture is allowed to stand in a separation tank, a method using a coalescer, a method using centrifugation, a method using adsorption, and the like.

[0028] Examples of the water-soluble liquid component (2c) include acetone, methanol, ethanol, propanol, etc. Examples of the water-insoluble liquid component (2d) include hydrocarbons having 5 or more carbon atoms, butanol, pentanol, etc.

[0029] By including the oil-water separation step (2-1) in the gas-liquid separation step (2), it becomes possible to recover and reuse the compounds contained in the water-soluble liquid component (2c) and the water-insoluble liquid component (2d).

[0030] [Gas Component Purification Step (3)] The method for producing ethylene and propylene according to this embodiment includes a gas component purification step (3) in which the gas component (2a) obtained in the gas-liquid separation step (2) is purified to obtain a gas component (3a) containing ethylene and propylene.

[0031] The gas component purification step (3) according to this embodiment is a step of separating and purifying oxygen-containing compounds contained in the gas component (2a) containing ethylene and propylene obtained in the gas-liquid separation step (2). The gas component purification step (3) may be any method capable of separating oxygen-containing compounds contained in the gas component (2a). The gas component purification step (3) may include multiple steps, such as an aldol condensation substance removal step (3-1), a carbon dioxide separation step (3-2), an alcohol removal step (3-3), and an organic acid removal step (3-4).

[0032] 3 is a process flow diagram showing a method for producing ethylene and propylene according to a first aspect of this embodiment. As shown in FIG. 3, in the method for producing ethylene and propylene according to this embodiment, the gas component purification step (3) includes, as a first aspect, a carbon dioxide separation step (3-2) in which carbon dioxide (3b) is separated from the gas component (2a) obtained in the gas-liquid separation step (2) to obtain a gas component (3a) containing ethylene and propylene. In the first aspect, the amount of energy consumed in the rectification step described below can be further reduced.

[0033] Fig. 4 is a process flow diagram showing a method for producing ethylene and propylene according to a second aspect of this embodiment. As shown in Fig. 4, in the method for producing ethylene and propylene according to this embodiment, the gas component purification step (3) includes, as a second aspect, an aldol condensation substance removal step (3-1) in which an aldol condensation substance (3c) is removed from the gas component (2a) obtained in the gas-liquid separation step (2) to obtain a gas component (3a') containing ethylene and propylene, and a carbon dioxide separation step (3-2) in which carbon dioxide (3b) is separated from the gas component (3a') obtained in the aldol condensation substance removal step (3-1) to obtain a gas component (3a) containing ethylene and propylene. In the second aspect, the amount of energy consumed in the rectification step can be further reduced.

[0034] Fig. 5 is a process flow diagram showing a method for producing ethylene and propylene according to a third aspect of this embodiment. As shown in Fig. 5, in the method for producing ethylene and propylene according to this embodiment, the gas component purification step (3) includes, as a third aspect, a carbon dioxide separation step (3-2) in which carbon dioxide (3b) is separated from the gas component (2a) obtained in the gas-liquid separation step (2) to obtain a gas component (3a'') containing ethylene and propylene, and an alcohol removal step (3-3) in which alcohol (3d) is removed from the gas component (3a'') obtained in the carbon dioxide separation step (3-2) to obtain a gas component (3a) containing ethylene and propylene. In the third aspect, the energy consumption in the rectification step can be further reduced.

[0035] Fig. 6 is a process flow diagram showing a method for producing ethylene and propylene according to a fourth aspect of this embodiment. As shown in Fig. 6, in the method for producing ethylene and propylene according to this embodiment, the gas component purification step (3) includes, as a fourth aspect, an aldol condensation substance removal step (3-1) in which an aldol condensation substance (3c) is removed from the gas component (2a) obtained in the gas-liquid separation step (2) to obtain a gas component (3a') containing ethylene and propylene, a carbon dioxide separation step (3-2) in which carbon dioxide (3b) is separated from the gas component (3a') obtained in the aldol condensation substance removal step (3-1) to obtain a gas component (3a") containing ethylene and propylene, and an alcohol removal step (3-3) in which an alcohol (3d) is removed from the gas component (3a") obtained in the carbon dioxide separation step (3-2) to obtain a gas component (3a) containing ethylene and propylene. In the fourth aspect, the energy consumption in the rectification step can be further reduced.

[0036] (Aldol Condensation Substance Removal Step (3-1)) In the method for producing ethylene and propylene according to this embodiment, the gas component purification step (3) may include an aldol condensation substance removal step (3-1) in which an aldol condensation substance (3c) is removed from the gas component (2a) obtained in the gas-liquid separation step (2) to obtain a gas component (3a′) containing ethylene and propylene.

[0037] The aldol condensation product (3c) is produced by a side reaction in the reaction step (1). Examples of such side reactions include the production reaction of acetaldehyde, acetone, etc. in the reaction step (1), and their condensation reaction. The aldol condensation product further reacts under acidic or basic conditions to become heavier or polymerize. The heavier or polymerized aldol condensation product adheres to the walls, piping, etc. of the distillation column used in the purification, causing a decrease in heat removal capacity, piping blockage, etc., and is known as a substance that reduces production stability. Therefore, in the method for producing ethylene and propylene according to this embodiment, the gas component purification step (3) includes the aldol condensation product removal step (3-1), which allows the aldol condensation product (3c) to be removed as much as possible, thereby achieving excellent production stability.

[0038] Examples of methods for removing the aldol condensation substance (3c) from the gas component (2a) include washing with water, a method in which the aldol condensation is carried out and then the aldol condensation substance produced by the condensation is removed by distillation, and a solid adsorption method, solid absorption method, etc. These methods may be used in combination of two or more. The water may be neutral water, an acidic aqueous solution, or a basic aqueous solution.

[0039] FIG. 7 is a process flow diagram showing an example of a method for producing ethylene and propylene according to this embodiment. As shown in FIG. 7 , in the method for producing ethylene and propylene according to this embodiment, the aldol condensation substance removal step (3-1) may include a washing step in which water is contacted with the gas component (2a) obtained in the gas-liquid separation step (2) to wash the gas component (2a). The washing step can be carried out by a water washing method. An example of a water washing method is a method for separating and recovering an aldol condensation substance (3c) contained in the gas component (2a), in which the aldol condensation substance (3c) is absorbed into water. When the aldol condensation substance removal step (3-1) includes a washing step, excellent production stability is achieved.

[0040] From the viewpoint of further improving the stability of production, the washing step is preferably carried out two or more times.

[0041] 8 is a process flow diagram showing an example of a method for producing ethylene and propylene according to this embodiment. As shown in FIG. 8 , in the method for producing ethylene and propylene according to this embodiment, the aldol condensation substance removal step (3-1) may include a step of contacting the gas component (2a) obtained in the gas-liquid separation step (2) with neutral water to wash the gas component (2a), then contacting the gas component (2a) with a basic aqueous solution to obtain an aldol condensation substance (3c), and separating the obtained aldol condensation substance (3c) from the gas component (2a) and the basic aqueous solution. This step can be performed by a method in which the aldol condensation is performed and then the aldol condensation substance produced by the condensation is removed by distillation. An example of such a method is to contact an aqueous solution containing the aldol condensation substance (3c) produced in the reaction step (1) with a basic substance to produce an aldol condensation substance (3c) having a higher boiling point than the aldol condensation substance (3c), and then remove the aldol condensation substance (3c) by distillation. The aldol condensation substance removal step (3-1) includes a step of contacting the gas component (2a) produced in the gas-liquid separation step (2) with neutral water to wash the gas component (2a), then contacting the gas component (2a) with a basic aqueous solution to produce the aldol condensation substance (3c), and separating the aldol condensation substance (3c) from the gas component (2a) and the basic aqueous solution. This allows a larger amount of the aldol condensation substance (3c) to be removed, thereby further improving the stability of production.

[0042] Examples of basic substances include sodium hydroxide and potassium hydroxide.

[0043] The contact of the aqueous solution containing the aldol condensable substance (3c) with the basic substance may be carried out in the form of a bubble column, a spray column, a packed column, a plate column, or the like.

[0044] FIG. 9 is a process flow diagram showing an example of a method for producing ethylene and propylene according to this embodiment. As shown in FIG. 9 , in order to achieve excellent production stability, in the method for producing ethylene and propylene according to this embodiment, the aldol condensation substance removal step (3-1) may include a step of removing the aldol condensation substance (3c) by adsorption. This step can be carried out by a solid adsorption method that is used to remove the aldol condensation substance (3c). Examples of the solid adsorption method used to remove the aldol condensation substance (3c) include a method for separating and recovering the aldol condensation substance (3c) by utilizing the pressure-temperature dependence of the amount of the aldol condensation substance adsorbed on a solid adsorbent. Examples of the adsorbent include zeolite and activated carbon. The removal of the aldol condensation substance (3c) by the solid adsorption method may use one or more adsorbents. The removal of the aldol condensation substance (3c) by the solid adsorption method may be carried out two or more times.

[0045] Examples of the solid absorption method used to remove the aldol condensation substance (3c) include a method for separating and recovering the aldol condensation substance (3c) using a solid absorbent. Examples of the solid absorbent include an amine compound used as an absorbing solution in a chemical absorption method, which is supported on or coated on a support. Examples of the support include organic materials such as polymethyl methacrylate beads and styrene beads, silica, alumina, clay minerals, silica alumina, magnesia, zirconia, lithium silicate, and mixtures thereof. The removal of the aldol condensation substance by the solid absorption method may use one or more solid absorbents. The removal of the aldol condensation substance (3c) by the solid absorption method may be carried out two or more times.

[0046] (Carbon Dioxide Separation Step (3-2)) In the method for producing ethylene and propylene according to this embodiment, the gas component purification step (3) may include a carbon dioxide separation step (3-2) in which carbon dioxide (3b) is separated from the gas component (2a) obtained in the gas-liquid separation step (2), the gas component (3a') obtained in the aldol condensation substance removal step (3-1), or the gas component (3a''') obtained in the organic acid removal step (3-4) described below, to obtain a gas component (3a) containing ethylene and propylene.

[0047] Examples of methods for separating carbon dioxide (3b) from gas component (2a), gas component (3a'), or gas component (3a''') (hereinafter, sometimes referred to as "gas components, etc." in this step) include chemical absorption, physical absorption, solid adsorption, solid absorption, and membrane separation. These methods may be used in combination of two or more.

[0048] Examples of chemical absorption methods used to separate carbon dioxide (3b) include carbon dioxide separation and recovery methods that utilize a chemical reaction between carbon dioxide and an absorbing solution. Examples of absorbing solutions include amine compounds and strongly basic aqueous solutions. Examples of amine compounds include monoethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine, monoisopropanolamine, diisopropanolamine, diglycolamine, 2-isopropylaminoethanol, and piperazine. Examples of strongly basic aqueous solutions include aqueous solutions of alkali metal hydroxides, aqueous solutions of alkaline earth metal hydroxides, and aqueous solutions of quaternary ammonium salts. Examples of aqueous solutions of alkali metal hydroxides include aqueous solutions of sodium hydroxide, potassium hydroxide, and lithium hydroxide. Examples of aqueous solutions of alkaline earth metal hydroxides include aqueous solutions of calcium hydroxide and barium hydroxide. Examples of aqueous solutions of quaternary ammonium salts include aqueous solutions of tetramethylammonium hydroxide. The strongly basic aqueous solution is preferably an aqueous solution of an alkali metal hydroxide or an aqueous solution of an alkaline earth metal hydroxide, more preferably an aqueous solution of an alkali metal hydroxide, and even more preferably an aqueous solution of sodium hydroxide or an aqueous solution of potassium hydroxide. Examples of methods for recovering carbon dioxide include heating an absorption liquid containing carbon dioxide to 110 to 130°C to dissociate the carbon dioxide from the absorption liquid, cooling a gas containing the dissociated carbon dioxide to condense the water in the gas, and separating the condensed water from the gas. Furthermore, carbon dioxide separation by chemical absorption may use one or more types of absorption liquid. Carbon dioxide separation by chemical absorption may be carried out two or more times.

[0049] The carbon dioxide separation step (3-2) may separate the carbon dioxide (3b) by a chemical absorption method using an amine compound. The carbon dioxide separation step (3-2) may separate the carbon dioxide (3b) by a chemical absorption method using a strongly basic aqueous solution, by a chemical absorption method using an aqueous solution of an alkali metal hydroxide or an aqueous solution of an alkaline earth metal hydroxide, or by a chemical absorption method using an aqueous solution of sodium hydroxide or an aqueous solution of potassium hydroxide.

[0050] From the viewpoint of excellent production stability, in one aspect of the method for producing ethylene and propylene according to the present embodiment, the carbon dioxide separation step (3-2) includes a step of separating a part of the carbon dioxide (3b) by a chemical absorption method using an amine compound, and then separating the remaining carbon dioxide (3b) by a chemical absorption method using a strongly basic aqueous solution.

[0051] An example of a physical absorption method used to separate carbon dioxide (3b) is a carbon dioxide separation and recovery method in which carbon dioxide is dissolved in an absorption liquid. Examples of the absorption liquid include N-methylpyrrolidone, methanol, a dimethyl ether solution of polyethylene glycol, and polypropylene carbonate. An example of a method for recovering carbon dioxide is a method in which an absorption liquid containing carbon dioxide is reduced in pressure or heated to separate carbon dioxide from the absorption liquid. Furthermore, separation of carbon dioxide by physical absorption may use one or more types of absorption liquid. Separation of carbon dioxide by physical absorption may be carried out two or more times.

[0052] An example of a solid adsorption method used in separating carbon dioxide (3b) is a carbon dioxide separation and recovery method that utilizes the pressure-temperature dependence of the amount of carbon dioxide adsorbed on a solid adsorbent. Examples of adsorbents include zeolite and activated carbon. An example of a method for recovering carbon dioxide is a method in which the carbon dioxide is desorbed from a solid adsorbent by reducing the pressure or heating the adsorbent. Furthermore, carbon dioxide separation by solid adsorption may use one or more types of adsorbents. Carbon dioxide separation by solid adsorption may be performed two or more times.

[0053] Examples of solid absorption methods used in separating carbon dioxide (3b) include carbon dioxide separation and recovery methods using solid absorbents. Examples of solid absorbents include those in which an amine compound used as an absorption liquid in chemical absorption methods is supported on or coated on a support. Examples of supports include organic materials such as polymethyl methacrylate beads and styrene beads, silica, alumina, clay minerals, silica alumina, magnesia, zirconia, lithium silicate, and mixtures thereof. Examples of methods for recovering carbon dioxide include heating or steam-treating a solid absorbent that has absorbed carbon dioxide to desorb the carbon dioxide from the solid absorbent, cooling the desorbed gas to condense the water in the gas, and separating the condensed water from the gas. Furthermore, carbon dioxide separation by solid absorption methods may use one or more solid absorbents. Carbon dioxide separation by solid absorption methods may be performed two or more times.

[0054] Examples of membrane separation methods include carbon dioxide separation and recovery methods that utilize a carbon dioxide separation membrane with carbon dioxide separation function. Examples of separation membranes include zeolite-based separation membranes, ceramic-based separation membranes, polyamide-amine-based separation membranes, aromatic polyimide-based separation membranes, and siloxane-based separation membranes. Examples of carbon dioxide separation membranes include those described in JP 2008-36463 A, JP 2012-232274 A, WO 2013 / 180218 A, WO 2019 / 131786 A, WO 2018 / 211945 A, JP 2017-176989 A, and JP 2016-163871 A. Carbon dioxide separation by membrane separation methods may use one or more types of separation membranes. Carbon dioxide separation by membrane separation methods may be performed two or more times.

[0055] When supplying gas components, etc. to a separation membrane, the dew point of the gas components, etc. may be controlled by drying the gas components, etc. before supplying them to the separation membrane, as described in, for example, JP 2012-232274 A. In the carbon dioxide separation step (3-2), pretreatment of the supply gas may be carried out depending on the type of separation membrane used. For example, Journal of Membrane Science, Vol. 228, 2004, pp. 227-236, describes that hydrocarbons such as propane and butane or aromatic hydrocarbons such as toluene reduce the performance of polyimide membranes. In such cases, the performance degradation of the separation membrane can be prevented by removing the hydrocarbons or aromatic hydrocarbons in advance.

[0056] In the carbon dioxide separation step (3-2), carbon dioxide (3b) may be separated by a membrane separation method.

[0057] From the viewpoint of excellent production stability, in one aspect of the method for producing ethylene and propylene according to this embodiment, the carbon dioxide separation step (3-2) includes a step of separating a part of the carbon dioxide (3b) by a membrane separation method and then separating the remaining carbon dioxide (3b) by a chemical absorption method.

[0058] From the viewpoint of excellent production stability, in another aspect of the method for producing ethylene and propylene according to the present embodiment, the carbon dioxide separation step (3-2) includes a step of separating a part of the carbon dioxide (3b) by a membrane separation method, then further separating the carbon dioxide (3b) by a chemical absorption method using an amine compound, and then separating the remaining carbon dioxide (3b) by a chemical absorption method using a strongly basic aqueous solution.

[0059] (Alcohol Removal Step (3-3)) In the method for producing ethylene and propylene according to this embodiment, the gas component purification step (3) may include an alcohol removal step (3-3) in which the alcohol (3d) is removed from the gas component (3a″) obtained in the carbon dioxide separation step (3-2) to obtain a gas component (3a) containing ethylene and propylene.

[0060] Examples of methods for separating the alcohol (3d) from the gas component (3a″) include physical absorption, solid adsorption, solid absorption, and membrane separation. These methods may be used in combination of two or more.

[0061] The physical absorption method used to separate the alcohol (3d) may be, for example, a method of separating and recovering alcohol by dissolving the alcohol in an absorbing liquid. The absorbing liquid may be, for example, water. Furthermore, the separation of alcohol by physical absorption may use one or more absorbing liquids. The separation of alcohol by physical absorption may be carried out two or more times.

[0062] FIG. 10 is a process flow diagram showing an example of a method for producing ethylene and propylene according to this embodiment. As shown in FIG. 10 , in one aspect of the method for producing ethylene and propylene according to this embodiment, from the viewpoint of excellent production stability, the alcohol removal step (3-3) may include a step of removing the alcohol (3d) by adsorption. This step can be carried out by a solid adsorption method used to separate the alcohol (3d). Examples of solid adsorption methods used to separate the alcohol (3d) include alcohol separation and recovery methods that utilize the pressure-temperature dependence of the amount of alcohol adsorbed on a solid adsorbent. Examples of adsorbents include zeolite and activated carbon. Alcohol separation by solid adsorption may use one or more adsorbents. Alcohol separation by solid adsorption may be carried out two or more times.

[0063] 11 is a process flow diagram showing an example of the method for producing ethylene and propylene according to this embodiment. As shown in FIG. 11 , in another aspect of the method for producing ethylene and propylene according to this embodiment, from the viewpoint of excellent production stability, the aldol condensation substance removal step (3-1) may include a step of removing the aldol condensation substance (3c) by adsorption, and the alcohol removal step (3-3) may include a step of removing the alcohol (3d) by adsorption.

[0064] Examples of the solid absorption method used in separating the alcohol (3d) include an alcohol separation and recovery method using a solid absorbent. Examples of the solid absorbent include an amine compound used as an absorption liquid in a chemical absorption method, supported on or coated on a support. Examples of the support include organic materials such as polymethyl methacrylate beads and styrene beads, silica, alumina, clay minerals, silica alumina, magnesia, zirconia, lithium silicate, and mixtures thereof. The separation of alcohol by the solid absorption method may use one or more solid absorbents. The separation of alcohol by the solid absorption method may be carried out two or more times.

[0065] An example of a membrane separation method is a method for separating and recovering alcohol using an alcohol separation membrane having an alcohol separation function. Examples of alcohol separation membranes include inorganic membranes such as zeolite membranes and silica membranes, and organic membranes such as polyimide membranes and polysulfone membranes. Furthermore, one or more types of separation membranes may be used for alcohol separation by membrane separation. Alcohol separation by membrane separation may be performed two or more times.

[0066] Specific examples of the alcohol (3d) include isopropanol, ethanol, and methanol. The alcohol (3d) may be one type of alcohol or a mixture of two or more types. The alcohol (3d) is preferably methanol.

[0067] (Organic Acid Removal Step (3-4)) In the method for producing ethylene and propylene according to this embodiment, the gas component purification step (3) may include an organic acid removal step (3-4) in which an organic acid (3e) is removed from the gas component (2a) obtained in the gas-liquid separation step (2) to obtain a gas component (3a''') containing ethylene and propylene.

[0068] The organic acid (3e) may be contained in the raw material or may be produced by a side reaction in the reaction step (1). The organic acid (3e) is known to be a substance that causes deterioration of the absorption liquid, adsorbent, solid absorbent, separation membrane, etc. used in the carbon dioxide separation step (3-2), thereby reducing the stability of production. Therefore, in the method for producing ethylene and propylene according to this embodiment, the gas component purification step (3) includes the organic acid removal step (3-4), which allows the organic acid (3e) to be removed as much as possible, thereby achieving excellent production stability.

[0069] Examples of methods for removing the organic acid (3e) from the gas component (2a) include washing with water, solid adsorption, and solid absorption. These methods may be used in combination of two or more. The water may be neutral water or a basic aqueous solution.

[0070] In the method for producing ethylene and propylene according to this embodiment, the organic acid removal step (3-4) may include a washing step in which the gas component (2a) obtained in the gas-liquid separation step (2) is brought into contact with water to wash the gas component (2a). The washing step can be carried out by a washing method using water. An example of a washing method using water is a method for removing the organic acid (3e) contained in the gas component (2a) by absorbing the organic acid (3e) into water. When the organic acid removal step (3-4) includes a washing step, excellent stability of production can be achieved.

[0071] The contact of the aqueous solution containing the organic acid (3e) with the basic substance may be carried out in a bubble column, a spray column, a packed column, a plate column, or the like.

[0072] In the method for producing ethylene and propylene according to this embodiment, the organic acid removal step (3-4) may include a step of removing the organic acid (3e) by adsorption. This step can be carried out by a solid adsorption method used to remove the organic acid (3e). Examples of the solid adsorption method used to remove the organic acid (3e) include a method of separating and recovering the organic acid (3e) by utilizing the pressure-temperature dependency of the amount of the organic acid adsorbed on a solid adsorbent. Examples of the adsorbent include zeolite and activated carbon. The removal of the organic acid (3e) by the solid adsorption method may use one or more types of adsorbents. The removal of the organic acid (3e) by the solid adsorption method may be carried out two or more times.

[0073] The solid absorption method used to remove the organic acid (3e) may, for example, be a method of separating and recovering the organic acid (3e) using a solid absorbent. Examples of the solid absorbent include an amine compound supported on or coated on a support. Examples of the support include organic materials such as polymethyl methacrylate beads and styrene beads, silica, alumina, clay minerals, silica alumina, magnesia, zirconia, lithium silicate, and mixtures thereof. The removal of the organic acid by the solid absorption method may use one or more solid absorbents. The removal of the organic acid (3e) by the solid absorption method may be carried out two or more times.

[0074] Fig. 12 is a process flow diagram showing a method for producing ethylene and propylene according to a fifth aspect of this embodiment. As shown in Fig. 12, in the fifth aspect of the method for producing ethylene and propylene according to this embodiment, the gas component purification step (3) includes an organic acid removal step (3-4) in which an organic acid (3e) is removed from the gas component (2a) obtained in the gas-liquid separation step (2) to obtain a gas component (3a''') containing ethylene and propylene, and a carbon dioxide separation step (3-2) in which carbon dioxide (3b) is separated from the gas component (3a''') obtained in the organic acid removal step (3-4) to obtain a gas component (3a) containing ethylene and propylene.

[0075] 13 is a process flow diagram showing a method for producing ethylene and propylene according to a sixth aspect of this embodiment. As shown in FIG. 13, the method for producing ethylene and propylene according to this embodiment, as a sixth aspect, comprises: an organic acid removal step (3-4) in which an organic acid (3e) is removed from the gas component (2a) obtained in the gas-liquid separation step (2) to obtain a gas component (3a'") containing ethylene and propylene; and a carbon dioxide separation step (3-2) in which carbon dioxide (3b) is separated from the gas component (3a'") obtained in the organic acid removal step (3-4) to obtain a gas component (3a) containing ethylene and propylene. The carbon dioxide separation step (3-2) comprises a step of separating a portion of the carbon dioxide (3b) by a chemical absorption method using an amine compound, and then separating the remaining carbon dioxide (3b) by a chemical absorption method using a strongly basic aqueous solution.

[0076] 14 is a process flow diagram showing a method for producing ethylene and propylene according to a seventh aspect of this embodiment. As shown in FIG. 14, the method for producing ethylene and propylene according to this embodiment, as a seventh aspect, includes an organic acid removal step (3-4) in which an organic acid (3e) is removed from the gas component (2a) obtained in the gas-liquid separation step (2) to obtain a gas component (3a'") containing ethylene and propylene, and a carbon dioxide separation step (3-2) in which carbon dioxide (3b) is separated from the gas component (3a'") obtained in the organic acid removal step (3-4) to obtain a gas component (3a) containing ethylene and propylene, and the carbon dioxide separation step (3-2) includes a step of separating a portion of the carbon dioxide (3b) by a membrane separation method and then separating the remaining carbon dioxide (3b) by a chemical absorption method.

[0077] [Naphtha Cracker Supply Step (4)] The method for producing ethylene and propylene according to this embodiment includes a naphtha cracker supply step (4) in which the gas component (3a) obtained in the gas component purification step (3) is supplied to a naphtha cracker to obtain ethylene and propylene.

[0078] 15 is a schematic diagram showing the configuration of a naphtha cracker in this embodiment. As shown in FIG. 15, the naphtha cracker, as one aspect, includes a cracking furnace 100 that cracks naphtha, which is a hydrocarbon mixture, in the presence of steam to produce a cracking discharge 100a, a quenching unit 101 that quenches the cracking discharge 100a with water to produce a cracking discharge 101a, a preliminary separation section 102 that removes heavy fractions and water from the quenched cracking discharge 101a to produce a product vapor 102a, a first compressor 103 that compresses the product vapor 102a to an appropriate pressure to produce a first compressed gas 103a, and a second compressor 104 that treats the first compressed gas 103a with caustic soda to produce a product vapor 102a. The naphtha cracker preferably includes a caustic wash section 104 that removes carbon dioxide from the caustic wash section 104 to produce gas 104a, a second compressor 105 that compresses the washed gas 104a to a suitable pressure to produce second compressed gas 105a, a moisture adsorption section 106 that removes residual moisture from the second compressed gas 105a to produce dry gas 106a, a hydrogen separation unit 107 that removes hydrogen from the dry gas 106a to produce gas 107a containing ethylene and propylene, and a rectification unit 108 that separates ethylene, propylene, and high-boiling components having a boiling point higher than that of propylene from the gas 107a containing ethylene and propylene. The naphtha cracker preferably includes the caustic wash section 104. The naphtha cracker preferably includes the moisture adsorption section 106.

[0079] The naphtha cracker feeding step (4) can be carried out at any location in the naphtha cracker.

[0080] In the naphtha cracker supply step (4), as a first embodiment, the gas component (3a) obtained in the gas component refining step (3) may be supplied to the naphtha cracker from upstream of the caustic washing section 104, as a second embodiment, the gas component (3a) obtained in the gas component refining step (3) may be supplied to the naphtha cracker from downstream of the caustic washing section 104, and as a third embodiment, the gas component (3a) obtained in the gas component refining step (3) may be supplied to the naphtha cracker from downstream of the moisture adsorption section 106.

[0081] In the naphtha cracker supply step (4), the gas component (3a) obtained in the gas component purification step (3) is preferably supplied to the naphtha cracker from one or more locations selected from the group consisting of the preliminary separation section 102, the first compressor 103, the second compressor 105, and the rectification unit 108. From the viewpoint of removing trace amounts of acid gas remaining in the gas component (3a) obtained in the gas component purification step (3), in the naphtha cracker supply step (4), the gas component (3a) obtained in the gas component purification step (3) is more preferably supplied to the naphtha cracker from the first compressor 103.

[0082] In the rectification unit 108, a rectification step of obtaining ethylene and propylene by purifying the gas 107a containing ethylene and propylene by distillation may be performed. The rectification step includes a methane separation step of separating methane from the gas 107a containing ethylene and propylene, an ethane separation step of separating ethane from the gas 107a containing ethylene and propylene, an ethylene obtaining step of obtaining ethylene from the gas 107a containing ethylene and propylene, and a propylene separation step of separating propylene from the gas 107a containing ethylene and propylene.

[0083] It is known that, among the processes performed in the rectification unit 108, processes with relatively low process temperatures can be heated using hot water recovered in the pre-separation section 102 of the naphtha cracker. For example, the hot water recovered in the pre-separation section 102 may be used as a heat source for an ethane separation process (Paul T. Scott, Yong Li Ma, Michael J. Tallman, ADVANCEMENTS IN C2 RECOVERY DISTILLATION, AIChE 2013 Spring National Meeting, April-May 2013). Furthermore, cold energy recovery to propylene refrigerant may be used as a heat source for the methane separation step and the ethylene acquisition step (David Gent, Mega-Cracker Cold Section Energy Integration, AIChE 2005 Spring National Meeting, April 2005). Therefore, among the steps performed in the rectification unit 108, the step that requires the addition of new heat from outside is the propylene separation step. Therefore, in the method for producing ethylene and propylene according to this embodiment, by including the naphtha cracker supply step (4), the propylene separation step can be the only step in the rectification step that substantially requires the addition of energy from outside, and therefore the amount of energy consumed in the rectification step can be further reduced.

[0084] The present invention includes the following aspects: [1] A method for producing ethylene and propylene, comprising: a reaction step (1) of contacting a raw material (1a) containing ethanol with a catalyst to obtain a product (1b) containing ethylene and propylene, a gas-liquid separation step (2) of separating the product (1b) obtained in the reaction step (1) into a gas component (2a) containing ethylene and propylene and a liquid component (2b) containing acetone, a gas component purification step (3) of purifying the gas component (2a) obtained in the gas-liquid separation step (2) to obtain a gas component (3a) containing ethylene and propylene, and a naphtha cracker supply step (4) of supplying the gas component (3a) obtained in the gas component purification step (3) to a naphtha cracker to obtain ethylene and propylene. [2] The method for producing ethylene and propylene according to [1], wherein the gas-liquid separation step (2) comprises an oil-water separation step (2-1) of separating a water-soluble liquid component (2c) and a water-insoluble liquid component (2d) from the liquid component (2b) obtained in the gas-liquid separation step (2). [3] The method for producing ethylene and propylene according to [1] or [2], wherein the gas component purification step (3) comprises a carbon dioxide separation step (3-2) of separating carbon dioxide (3b) from the gas component (2a) obtained in the gas-liquid separation step (2) to obtain a gas component (3a) containing ethylene and propylene. [4] The method for producing ethylene and propylene according to [1] or [2], wherein the gas component purification step (3) comprises: an aldol condensation substance removal step (3-1) of removing aldol condensation substances (3c) from the gas component (2a) obtained in the gas-liquid separation step (2) to obtain a gas component (3a') containing ethylene and propylene; and a carbon dioxide separation step (3-2) of separating carbon dioxide (3b) from the gas component (3a') obtained in the aldol condensation substance removal step (3-1) to obtain a gas component (3a) containing ethylene and propylene.[5] The method for producing ethylene and propylene according to [1] or [2], wherein the gas component purification step (3) comprises: a carbon dioxide separation step (3-2) of separating carbon dioxide (3b) from the gas component (2a) obtained in the gas-liquid separation step (2) to obtain a gas component (3a″) containing ethylene and propylene; and an alcohol removal step (3-3) of removing alcohol (3d) from the gas component (3a″) obtained in the carbon dioxide separation step (3-2) to obtain a gas component (3a) containing ethylene and propylene. [6] The method for producing ethylene and propylene according to [1] or [2], wherein the gas component purification step (3) comprises: an organic acid removal step (3-4) of removing an organic acid (3e) from the gas component (2a) obtained in the gas-liquid separation step (2) to obtain a gas component (3a''') containing ethylene and propylene; and a carbon dioxide separation step (3-2) of separating carbon dioxide (3b) from the gas component (3a''') obtained in the organic acid removal step (3-4) to obtain a gas component (3a) containing ethylene and propylene. [7] The method for producing ethylene and propylene according to [1] or [2], wherein the gas component purification step (3) comprises: an aldol condensation substance removal step (3-1) of removing aldol condensation substances (3c) from the gas component (2a) obtained in the gas-liquid separation step (2) to obtain a gas component (3a') containing ethylene and propylene; a carbon dioxide separation step (3-2) of separating carbon dioxide (3b) from the gas component (3a') obtained in the aldol condensation substance removal step (3-1) to obtain a gas component (3a'') containing ethylene and propylene; and an alcohol removal step (3-3) of removing alcohol (3d) from the gas component (3a'') obtained in the carbon dioxide separation step (3-2) to obtain a gas component (3a) containing ethylene and propylene. [8] The method for producing ethylene and propylene according to [4] or [7], wherein the aldol condensation substance removal step (3-1) comprises a washing step of bringing water into contact with the gas component (2a) obtained in the gas-liquid separation step (2) to wash the gas component (2a). [9] The method for producing ethylene and propylene according to [8], wherein the washing step is carried out two or more times.

[10] The method for producing ethylene and propylene according to any one of [4] or [7] to [9], wherein the aldol condensation substance removal step (3-1) comprises a step of contacting the gas component (2a) obtained in the gas-liquid separation step (2) with neutral water to wash the gas component (2a), then contacting the gas component (2a) with a basic aqueous solution to obtain an aldol condensation substance (3c), and separating the obtained aldol condensation substance (3c) from the gas component (2a) and the basic aqueous solution.

[11] The method for producing ethylene and propylene according to any one of [4] or [7] to [9], wherein the aldol condensation substance removal step (3-1) comprises a step of removing the aldol condensation substance (3c) by adsorption.

[12] The method for producing ethylene and propylene according to any one of [3] to

[11] , wherein the carbon dioxide separation step (3-2) comprises separating a portion of the carbon dioxide (3b) by a chemical absorption method using an amine compound, and then separating the remaining carbon dioxide (3b) by a chemical absorption method using a strongly basic aqueous solution.

[13] The method for producing ethylene and propylene according to any one of [3] to

[11] , wherein the carbon dioxide separation step (3-2) comprises separating a portion of the carbon dioxide (3b) by a membrane separation method, and then separating the remaining carbon dioxide (3b) by a chemical absorption method.

[14] The method for producing ethylene and propylene according to [5] or [7], wherein the alcohol removal step (3-3) comprises removing the alcohol (3d) by adsorption.

[15] The method for producing ethylene and propylene according to [7], wherein the aldol condensation substance removal step (3-1) comprises a step of removing aldol condensation substances (3c) by adsorption, and the alcohol removal step (3-3) comprises a step of removing alcohol (3d) by adsorption.

[16] The method for producing ethylene and propylene according to any one of [1] to

[15] , wherein the naphtha cracker has a caustic wash section, and in the naphtha cracker supply step (4), the gas component (3a) obtained in the gas component purification step (3) is supplied to the naphtha cracker from upstream of the caustic wash section.

[17] The method for producing ethylene and propylene according to any one of [1] to

[15] , wherein the naphtha cracker has a caustic washing section, and in the naphtha cracker supply step (4), the gas component (3a) obtained in the gas component refining step (3) is supplied to the naphtha cracker from downstream of the caustic washing section.

[18] The method for producing ethylene and propylene according to any one of [1] to

[15] , wherein the naphtha cracker has a moisture adsorption section, and in the naphtha cracker supply step (4), the gas component (3a) obtained in the gas component refining step (3) is supplied to the naphtha cracker from downstream of the moisture adsorption section.

[0085] The method for producing ethylene and propylene according to the present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the spirit of the present invention. In addition, the configurations, methods, etc. of embodiments other than those described above may be arbitrarily adopted and combined, and the configurations, methods, etc. of one embodiment described above may be applied to the configurations, methods, etc. of other embodiments described above.

[0086] The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to these examples.

[0087] Example 1 In a method for producing ethylene and propylene in which a naphtha cracker supply step (4) is carried out, the required heat amount, required steam amount, and carbon dioxide equivalent amount per unit mass of ethylene and propylene (also referred to as "olefins") obtained in the rectification unit in each of the methane separation step, ethane separation step, ethylene acquisition step, and propylene separation step carried out in the rectification unit of the naphtha cracker were calculated using Aspen Plus, a general-purpose process simulator. Note that the "required heat amount" refers to the amount of heat consumed in the process per unit mass of the olefin, the "required steam amount" refers to the amount of steam consumed in the process per unit mass of the olefin, and the "carbon dioxide equivalent amount" refers to the amount of carbon dioxide generated in the process per unit mass of the olefin.

[0088] Comparative Example 1 The required heat quantity, required steam amount, and carbon dioxide equivalent amount were calculated in the same manner as in Example 1, except that the naphtha cracker supply step (4) was not performed.

[0089] <Energy Consumption in Rectification Step> The required heat quantity, required steam amount, and carbon dioxide equivalent amount in the rectification step were calculated as the energy consumption in the rectification step in Example 1 and Comparative Example 1. The required heat quantity in the rectification step indicates the total value of the required heat quantities in the methane separation step, ethane separation step, ethylene obtaining step, and propylene separation step, the required steam amount in the rectification step indicates the total value of the required steam amounts in the methane separation step, ethane separation step, ethylene obtaining step, and propylene separation step, and the carbon dioxide equivalent amount in the rectification step indicates the total value of the carbon dioxide equivalent amounts in the methane separation step, ethane separation step, ethylene obtaining step, and propylene separation step.

[0090] The heat quantity, steam quantity, and carbon dioxide equivalent quantity required for the rectification step in Example 1 and Comparative Example 1 are shown in Table 1. Note that the "process temperature" in Table 1 refers to the temperature at which the step was carried out.

[0091]

[0092] The required heat quantity, required steam quantity, and carbon dioxide equivalent amount in the ethane separation step in Example 1 were calculated assuming that hot water recovered in the preliminary separation section of the naphtha cracker was used as a heat source in the ethane separation step. The required heat quantity, required steam quantity, and carbon dioxide equivalent amount in the methane separation step and ethylene production step in Example 1 were calculated assuming that cold heat recovered to propylene refrigerant was used as a heat source in the methane separation step and ethylene production step.

[0093] From Table 1, it can be seen that in Example 1 in which the naphtha cracker supply step (4) is performed, the amounts of heat used in the methane separation step, the ethane separation step, and the ethylene obtaining step can be reduced compared to Comparative Example 1 in which the naphtha cracker supply step (4) is not performed, and therefore the amount of heat required in the rectification step, the amount of steam required, and the carbon dioxide equivalent can be significantly reduced.

[0094] According to the present invention, it is possible to provide a method for producing ethylene and propylene, which can relatively reduce the amount of energy consumed in the rectification step.

Claims

1. A method for producing ethylene and propylene, comprising: a reaction step (1) of contacting a raw material (1a) containing ethanol with a catalyst to obtain a product (1b) containing ethylene and propylene; a gas-liquid separation step (2) of separating the product (1b) obtained in the reaction step (1) into a gas component (2a) containing ethylene and propylene and a liquid component (2b) containing acetone; a gas component purification step (3) of purifying the gas component (2a) obtained in the gas-liquid separation step (2) to obtain a gas component (3a) containing ethylene and propylene; and a naphtha cracker supply step (4) of supplying the gas component (3a) obtained in the gas component purification step (3) to a naphtha cracker to obtain ethylene and propylene.

2. The method for producing ethylene and propylene according to claim 1, wherein the gas-liquid separation step (2) includes an oil-water separation step (2-1) for separating a water-soluble liquid component (2c) and a water-insoluble liquid component (2d) from the liquid component (2b) obtained in the gas-liquid separation step (2).

3. The method for producing ethylene and propylene according to claim 1, wherein the gas component purification step (3) includes a carbon dioxide separation step (3-2) of separating carbon dioxide (3b) from the gas component (2a) obtained in the gas-liquid separation step (2) to obtain a gas component (3a) containing ethylene and propylene.

4. The method for producing ethylene and propylene according to claim 1, wherein the gas component purification step (3) comprises: an aldol condensation substance removal step (3-1) of removing aldol condensation substances (3c) from the gas component (2a) obtained in the gas-liquid separation step (2) to obtain a gas component (3a') containing ethylene and propylene; and a carbon dioxide separation step (3-2) of separating carbon dioxide (3b) from the gas component (3a') obtained in the aldol condensation substance removal step (3-1) to obtain a gas component (3a) containing ethylene and propylene.

5. The method for producing ethylene and propylene according to claim 1, wherein the gas component purification step (3) comprises: a carbon dioxide separation step (3-2) of separating carbon dioxide (3b) from the gas component (2a) obtained in the gas-liquid separation step (2) to obtain a gas component (3a'') containing ethylene and propylene; and an alcohol removal step (3-3) of removing alcohol (3d) from the gas component (3a'') obtained in the carbon dioxide separation step (3-2) to obtain a gas component (3a) containing ethylene and propylene.

6. The method for producing ethylene and propylene according to claim 1, wherein the gas component purification step (3) comprises: an organic acid removal step (3-4) of removing an organic acid (3e) from the gas component (2a) obtained in the gas-liquid separation step (2) to obtain a gas component (3a''') containing ethylene and propylene; and a carbon dioxide separation step (3-2) of separating carbon dioxide (3b) from the gas component (3a''') obtained in the organic acid removal step (3-4) to obtain a gas component (3a) containing ethylene and propylene.

7. The method for producing ethylene and propylene according to claim 1, wherein the gas component purification step (3) comprises: an aldol condensation substance removal step (3-1) of removing aldol condensation substances (3c) from the gas component (2a) obtained in the gas-liquid separation step (2) to obtain a gas component (3a') containing ethylene and propylene; a carbon dioxide separation step (3-2) of separating carbon dioxide (3b) from the gas component (3a') obtained in the aldol condensation substance removal step (3-1) to obtain a gas component (3a'') containing ethylene and propylene; and an alcohol removal step (3-3) of removing alcohol (3d) from the gas component (3a'') obtained in the carbon dioxide separation step (3-2) to obtain a gas component (3a) containing ethylene and propylene.

8. The method for producing ethylene and propylene according to claim 4, wherein the aldol condensation substance removal step (3-1) includes a washing step of bringing water into contact with the gas component (2a) obtained in the gas-liquid separation step (2) to wash the gas component (2a).

9. The method for producing ethylene and propylene according to claim 8, wherein the washing step is carried out two or more times.

10. The method for producing ethylene and propylene according to claim 4, wherein the aldol condensation substance removal step (3-1) comprises the steps of contacting the gas component (2a) obtained in the gas-liquid separation step (2) with neutral water to wash the gas component (2a), then contacting the gas component (2a) with a basic aqueous solution to obtain an aldol condensation substance (3c), and separating the obtained aldol condensation substance (3c) from the gas component (2a) and the basic aqueous solution.

11. The method for producing ethylene and propylene according to claim 4 or any one of claims 7 to 9, wherein the aldol condensation substance removal step (3-1) includes a step of removing the aldol condensation substance (3c) by adsorption.

12. The method for producing ethylene and propylene according to any one of claims 3 to 10, wherein the carbon dioxide separation step (3-2) comprises a step of separating a portion of the carbon dioxide (3b) by a chemical absorption method using an amine compound, and then separating the remaining carbon dioxide (3b) by a chemical absorption method using a strongly basic aqueous solution.

13. The method for producing ethylene and propylene according to any one of claims 3 to 10, wherein the carbon dioxide separation step (3-2) comprises a step of separating a portion of the carbon dioxide (3b) by a membrane separation method, and then separating the remaining carbon dioxide (3b) by a chemical absorption method.

14. The method for producing ethylene and propylene according to claim 5 or 7, wherein the alcohol removal step (3-3) includes a step of removing the alcohol (3d) by adsorption.

15. The method for producing ethylene and propylene according to claim 7, wherein the aldol condensation substance removal step (3-1) comprises a step of removing an aldol condensation substance (3c) by adsorption, and the alcohol removal step (3-3) comprises a step of removing an alcohol (3d) by adsorption.

16. The method for producing ethylene and propylene according to any one of claims 1 to 10, wherein the naphtha cracker has a caustic washing section, and in the naphtha cracker supply step (4), the gas component (3a) obtained in the gas component purification step (3) is supplied to the naphtha cracker from upstream of the caustic washing section.

17. The method for producing ethylene and propylene according to any one of claims 1 to 10, wherein the naphtha cracker has a caustic washing section, and in the naphtha cracker supply step (4), the gas component (3a) obtained in the gas component purification step (3) is supplied to the naphtha cracker from downstream of the caustic washing section.

18. The method for producing ethylene and propylene according to any one of claims 1 to 10, wherein the naphtha cracker has a moisture adsorption section, and in the naphtha cracker supply step (4), the gas component (3a) obtained in the gas component purification step (3) is supplied to the naphtha cracker from downstream of the moisture adsorption section.

Images