Method for producing olefin and execution process

Abstract

This method for producing an olefin comprises: a thermal decomposition step for thermally decomposing a waste plastic starting material so as to obtain a hydrocarbon stream; a crude olefin generation step for supplying the hydrocarbon stream to a catalytic decomposition device that brings a catalyst into contact with a hydrocarbon and decomposes the hydrocarbon so as to obtain a crude olefin; a separation step for separating an olefin having 2-4 carbon atoms from the crude olefin; a catalyst regeneration step for regenerating the catalyst used in the crude olefin generation step using a catalyst regeneration device and returning the regenerated catalyst to the catalytic decomposition device; and an exhaust gas treatment step for heating exhaust gas generated in the catalyst regeneration device using an exhaust gas treatment device and burning and decomposing harmful substances. The temperature of the exhaust gas treatment device in the exhaust gas treatment step is higher than the temperature of the catalyst regeneration device in the catalyst regeneration step.

Description

Method and implementation process for producing olefins Cross-Reference to Related Applications

[0001] The present application claims priority from Japanese Patent Application No. 2025-054641 and Japanese Patent Application No. 2026-040194, the disclosures of which are incorporated herein by reference.

[0002] The present invention relates to a method and implementation process for producing olefins.

[0003] Plastic products are produced using, for example, petrochemical products obtained by a method of cracking crude oil-derived hydrocarbons as raw materials. There are many such cracking methods, and examples of cracking methods using a catalyst include fluid catalytic cracking. In fluid catalytic cracking, hydrocarbon oil is subjected to catalytic cracking using a catalyst containing zeolite or the like, and separation and purification are performed to obtain petrochemical products, fuel oil, and the like.

[0004] In the fluid catalytic cracking as described above, it is known that high-molecular-weight components such as heavy oil contained in crude oil or aromatic components undergo polycondensation to form carbides (also referred to as coke), and the coke is generated on the catalyst surface to degrade catalytic activity. Therefore, in fluid catalytic cracking, in order to maintain catalytic activity, a step of regenerating the catalyst by burning the coke generated on the catalyst surface and removing the coke from the catalyst (also referred to as a catalyst regeneration step) is performed (see Patent Document 1). In the catalyst regeneration step, when coke is burned, the catalyst is regenerated, and exhaust gas such as carbon dioxide is generated.

[0005] Japanese Unexamined Patent Application Publication No. 2006-305490

[0006] Incidentally, from the viewpoint of resource recycling, the regeneration and reuse of plastics have attracted attention. For example, treatments such as reuse, material recycling, and chemical recycling are performed to recycle waste plastics. In particular, chemical recycling can chemically decompose plastics and regenerate them into petrochemical raw materials, so it has the potential to overcome the limit of performance degradation caused by recycling.

[0007] However, when catalytic cracking is performed using hydrocarbon flow obtained by thermally decomposing waste plastic raw materials, chlorine-containing compounds and other substances contained in the waste plastic adhere to the catalyst as coke, and when this coke is burned during the catalyst regeneration process, harmful substances such as dioxins are generated. Although these harmful substances can be burned and decomposed under high-temperature conditions, heating the catalyst to a temperature where these harmful substances can be burned and decomposed during the catalyst regeneration process may degrade the catalyst.

[0008] In view of the above-mentioned problems, the present invention aims to provide a method and process for producing olefins that suppress catalyst degradation while treating harmful substances contained in exhaust gas during catalytic cracking using waste plastic raw materials.

[0009] The method for producing olefins according to the present invention includes: a thermal decomposition step of obtaining a hydrocarbon flow by thermal decomposing a waste plastic raw material containing polyolefins; a crude olefin production step of obtaining crude olefins by supplying the hydrocarbon flow to a catalytic cracking apparatus that decomposes hydrocarbons by contacting a catalyst containing zeolite with hydrocarbons; a separation step of separating olefins having 2 to 4 carbon atoms from the crude olefins; a catalyst regeneration step of regenerating the catalyst used in the crude olefin production step using a catalyst regeneration apparatus that regenerates the catalyst by heating, and returning the regenerated catalyst to the catalytic cracking apparatus; and an exhaust gas treatment step of heating the exhaust gas generated in the catalyst regeneration apparatus using an exhaust gas treatment apparatus to burn and decompose harmful substances, wherein the temperature of the exhaust gas treatment apparatus in the exhaust gas treatment step is higher than the temperature of the catalyst regeneration apparatus in the catalyst regeneration step.

[0010] An implementation step for carrying out the method for producing the olefin, the implementation step comprising the thermal decomposition step.

[0011] An implementation step for carrying out the above-mentioned method for producing the olefin, comprising the crude olefin production step, the catalyst regeneration step, and the exhaust gas treatment step.

[0012] An implementation step for carrying out the method for producing the olefin, comprising the separation step.

[0013] ≪Method for Producing Olefins≫ The method for producing olefins according to embodiments of the present invention will be described below. The present invention is not limited to the following embodiments.

[0014] The method for producing olefins according to this embodiment includes: a thermal decomposition step of obtaining a hydrocarbon flow by thermal decomposing a waste plastic raw material containing polyolefin; a crude olefin production step of obtaining crude olefins by supplying the hydrocarbon flow to a catalytic cracking apparatus that decomposes hydrocarbons by contacting a catalyst containing zeolite with hydrocarbons; a separation step of separating olefins having 2 to 4 carbon atoms from the crude olefins; a catalyst regeneration step of regenerating the catalyst used in the crude olefin production step using a catalyst regeneration apparatus that regenerates the catalyst by heating, and returning the regenerated catalyst to the catalytic cracking apparatus; and an exhaust gas treatment step of heating the exhaust gas generated in the catalyst regeneration apparatus using an exhaust gas treatment apparatus to burn and decompose harmful substances.

[0015] First, the olefin manufacturing apparatus used in the olefin manufacturing method according to this embodiment will be described. The olefin manufacturing apparatus used in this embodiment includes: a pyrolysis apparatus that thermally decomposes waste plastic raw materials containing polyolefins to obtain a hydrocarbon flow; a catalytic cracking apparatus that receives the hydrocarbon flow and contacts a catalyst containing zeolite with hydrocarbons in the hydrocarbon flow to decompose hydrocarbons and obtain crude olefins; a separation apparatus that separates olefins having 2 to 4 carbon atoms from the crude olefins; a catalyst regeneration apparatus that regenerates the catalyst containing zeolite used in the catalytic cracking apparatus by heating and returns the regenerated catalyst to the catalytic cracking apparatus; and an exhaust gas treatment apparatus that heats the exhaust gas generated in the catalyst regeneration apparatus and burns and decomposes harmful substances.

[0016] [Pyrolysis Apparatus] The pyrolysis apparatus is a device that obtains a hydrocarbon flow by pyrolysis of waste plastic raw materials containing polyolefins. More specifically, the pyrolysis apparatus is a device that pyrolysiss waste plastic raw materials containing polyolefins to obtain pyrolysis products and obtains a hydrocarbon flow from the pyrolysis products. The pyrolysis apparatus has a reaction vessel for pyrolysis of the waste plastic raw materials. The hydrocarbon flow obtained from the pyrolysis apparatus is supplied to a catalytic cracking apparatus, which will be described later.

[0017] Examples of the pyrolysis apparatus include a stirred-tank pyrolysis apparatus, a rotary pyrolysis apparatus, an internal circulating fluidized bed apparatus, and an external circulating fluidized bed apparatus. The stirred-tank pyrolysis apparatus is an apparatus that pyrolysis waste plastic supplied to a reaction vessel by heating it from the outside while stirring it with a stirrer inside the reaction vessel. The rotary pyrolysis apparatus is an apparatus that pyrolysis waste plastic supplied to a reaction vessel while rotating it. The internal circulating fluidized bed apparatus and the external circulating fluidized bed apparatus are apparatuses that can promote pyrolysis by using a fluidized bed formed of fluidized solid particles. The pyrolysis apparatus may be used individually, or two or more types may be combined and connected in parallel or in series. When two or more types of pyrolysis apparatus are combined and connected in parallel, the pyrolysis apparatus may be used with all pyrolysis apparatuses operating simultaneously, or with some of the pyrolysis apparatuses stopped. The pyrolysis apparatus is preferably at least one selected from the group consisting of a stirred-tank pyrolysis apparatus, a rotary pyrolysis apparatus, an internal circulating fluidized bed apparatus, and an external circulating fluidized bed apparatus.

[0018] The internal pressure of the pyrolysis apparatus is preferably between atmospheric pressure - 50 kPaG and atmospheric pressure + 50 kPaG.

[0019] The pyrolysis apparatus may have at least one of a refluxing device and a condenser. The refluxing device and the condenser liquefy at least a portion of the pyrolysis product. The pyrolysis apparatus may have piping connecting the reaction vessel to at least one of the refluxing device and the condenser in order to supply at least a portion of the liquefied pyrolysis product back to the pyrolysis apparatus. The pyrolysis apparatus may have multiple refluxing devices and multiple condensers.

[0020] The pyrolysis apparatus may heat the waste plastic raw material using any heat source. Examples of the heat source include heat from burning fuel, heat generated by an electric heater, and heat generated during exhaust gas treatment. Examples of the fuel include gaseous pyrolysis products contained in the pyrolysis product, and natural gas. The pyrolysis apparatus may use one of the heat sources alone, or it may use two or more of the heat sources in combination.

[0021] [Catalytic Cracking Apparatus] The catalytic cracking apparatus is a device that receives the hydrocarbon stream and brings a catalyst containing zeolite into contact with the hydrocarbons in the hydrocarbon stream to decompose the hydrocarbons and obtain crude olefins, which will be described later. The hydrocarbons are those contained in the hydrocarbon stream obtained in the pyrolysis apparatus. The crude olefins obtained in the catalytic cracking apparatus are supplied to a separation apparatus, which will be described later.

[0022] Examples of the catalytic cracking apparatus include a fluidized bed catalytic cracking apparatus, a moving bed catalytic cracking apparatus, and a stationary bed catalytic cracking apparatus. The fluidized bed catalytic cracking apparatus is an apparatus that decomposes hydrocarbons by contacting hydrocarbons with a fluidized particulate catalyst. The moving bed catalytic cracking apparatus is an apparatus that decomposes hydrocarbons by contacting hydrocarbons with a granular catalyst as it moves from top to bottom within the apparatus. The catalytic cracking apparatus may be used individually, or two or more may be combined and connected in parallel or in series. The catalytic cracking apparatus is preferably at least one of a fluidized bed catalytic cracking apparatus and a moving bed catalytic cracking apparatus, and more preferably a fluidized bed catalytic cracking apparatus.

[0023] [Separation device] The separation device is a device for separating olefins having 2 to 4 carbon atoms from crude olefins. The separation device may also be a device for further separating fuel oil and fuel gas from crude olefins. That is, the separation device may be a device for separating olefins having 2 to 4 carbon atoms, fuel oil, and fuel gas from crude olefins. The olefins having 2 to 4 carbon atoms obtained in the separation device may be used as various petrochemical raw materials. The fuel oil and fuel gas obtained in the separation device may be supplied to an exhaust gas treatment device described later and used as fuel.

[0024] Examples of the separation apparatus include distillation apparatus, gas-liquid separator, adsorption separator, membrane separator, and washing apparatus. The separation apparatus may be used individually, or two or more may be combined and connected in parallel or in series. When the separation apparatus is used individually, the separation apparatus is preferably a distillation apparatus. When multiple separation apparatuses are used, the multiple separation apparatuses are preferably at least two selected from the group consisting of distillation apparatus, gas-liquid separator, adsorption separator, membrane separator, and washing apparatus.

[0025] [Catalyst Regeneration Device] The catalyst regeneration device is a device that regenerates the catalyst containing zeolite used in the catalytic cracking device by heating, and returns the regenerated catalyst to the catalytic cracking device. The catalyst regenerated in the catalyst regeneration device is the catalyst used in the catalytic cracking device. The catalyst regenerated in the catalyst regeneration device is supplied again to the catalytic cracking device. When the catalyst is regenerated in the catalyst regeneration device, exhaust gas is generated. The exhaust gas is supplied to an exhaust gas treatment device, which will be described later.

[0026] Examples of the catalyst regeneration apparatus include a fluidized bed catalyst regeneration apparatus, a mobile bed catalyst regeneration apparatus, and a stationary bed catalyst regeneration apparatus. The fluidized bed catalyst regeneration apparatus is an apparatus that regenerates a catalyst by heating it when fluidized particulate catalyst comes into contact with air. The mobile bed catalyst regeneration apparatus is an apparatus that regenerates a catalyst by heating it as granular catalyst moves from top to bottom inside the apparatus. The catalyst regeneration apparatus may be used individually, or two or more may be combined and connected in parallel or in series. The catalyst regeneration apparatus is preferably at least one of a fluidized bed catalyst regeneration apparatus and a mobile bed catalyst regeneration apparatus, and more preferably a fluidized bed catalyst regeneration apparatus.

[0027] [Exhaust Gas Treatment Device] The exhaust gas treatment device is a device that heats the exhaust gas generated by the catalyst regeneration device and burns and decomposes harmful substances. When the exhaust gas is heated in the exhaust gas treatment device, the harmful substances contained in the exhaust gas are burned and decomposed, rendering the exhaust gas harmless. The exhaust gas rendered harmless by the exhaust gas treatment device is released into the atmosphere. In this specification, "detoxification" means that the concentration of harmful substances in the exhaust gas is reduced to a concentration that meets the emission standards stipulated in the Special Measures Law Concerning Countermeasures against Dioxins or the Air Pollution Control Law.

[0028] Examples of the exhaust gas treatment devices include direct combustion type exhaust gas treatment devices and indirect heating type exhaust gas treatment devices. The direct combustion type exhaust gas treatment device is a device that supplies air and fuel to the device, burns the fuel to heat the exhaust gas, and burns and decomposes harmful substances in the exhaust gas. The indirect heating type exhaust gas treatment device is a device that heats the exhaust gas with a heated heat storage material to burn and decompose harmful substances in the exhaust gas. The indirect heating type exhaust gas treatment device may also be a device that heats a gas mixture of air supplied to the device and the exhaust gas with a heated heat storage material to burn and decompose harmful substances in the exhaust gas. The exhaust gas treatment devices may be used individually, or two or more may be combined and connected in parallel or in series. The exhaust gas treatment device is preferably the direct combustion type exhaust gas treatment device.

[0029] The exhaust gas treatment device may include a filter, an adsorption tower, or a scrubbing tower for reducing the concentration of harmful substances in the heated exhaust gas.

[0030] The exhaust gas treatment device may include a heat exchanger. The amount of heat obtained by passing the heated exhaust gas through the heat exchanger may be used to generate steam or to heat the air.

[0031] Next, a method for producing olefins according to this embodiment will be described. The method for producing olefins according to this embodiment includes a thermal decomposition step, a crude olefin production step, a separation step, a catalyst regeneration step, and an exhaust gas treatment step.

[0032] (Thermal Decomposition Process) The thermal decomposition process is a process of thermally decomposing a waste plastic raw material containing polyolefin to obtain a hydrocarbon flow. More specifically, the thermal decomposition process is a process of thermally decomposing a waste plastic raw material containing polyolefin to obtain a thermal decomposition product, and obtaining a hydrocarbon flow from the thermal decomposition product. The thermal decomposition process includes a reaction that reduces the molecular weight of the polymer components contained in the waste plastic raw material and converts them into hydrocarbons. That is, the hydrocarbon flow obtained in the thermal decomposition process contains hydrocarbons. In the thermal decomposition process, thermal decomposition residue may be generated from the waste plastic raw material.

[0033] The pyrolysis step can be carried out using the pyrolysis apparatus described above. Preferably, the pyrolysis step can be carried out using at least one selected from the group consisting of a stirred-tank pyrolysis apparatus, a rotary pyrolysis apparatus, an internal circulating fluidized bed apparatus, and an external circulating fluidized bed apparatus.

[0034] The aforementioned waste plastic raw materials refer to plastic products that have been used for some end-use purpose.

[0035] Examples of polyolefins included in the waste plastic raw material include olefin polymers containing monomer units derived from α-olefins. The olefin polymer may be an olefin homopolymer or a copolymer containing monomer units derived from olefins. The waste plastic raw material may contain at least one of the olefin polymer, an olefin homopolymer, and a copolymer containing monomer units derived from olefins.

[0036] Examples of monomers derived from olefins include ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, and 1-dodecene.

[0037] A copolymer containing monomer units derived from olefins may be a copolymer containing monomer units derived from two or more different olefins, or it may be a copolymer containing monomer units derived from olefins and monomer units other than those derived from olefins. The waste plastic raw material may contain one copolymer containing monomer units derived from olefins, or two or more copolymers as the olefin-based polymer.

[0038] Examples of monomers other than monomer units derived from olefins include alkylene oxides such as ethylene oxide and esters such as ethylene terephthalate. The monomers other than monomer units derived from olefins may be alkylene oxide or ethylene terephthalate.

[0039] Examples of copolymers containing monomer units derived from an olefin include propylene copolymers containing monomer units derived from propylene. Examples of the propylene copolymer include propylene-ethylene copolymer, propylene-1-butene copolymer, propylene-1-hexene copolymer, propylene-1-octene copolymer, propylene-ethylene-1-butene copolymer, propylene-ethylene-1-hexene copolymer, and propylene-ethylene-1-octene copolymer. The propylene copolymer may be a random copolymer or may be a heterophasic propylene polymer material.

[0040] The waste plastic raw material may contain polymer components other than the polyolefin. Examples of polymer components other than the polyolefin include chlorinated polyethylene, polyvinyl chloride (PVC), polyvinylidene chloride (PVDC), polyethylene terephthalate (PET), polybutylene terephthalate, polystyrene, and nylon 66.

[0041] From the viewpoint of increasing the content of polyolefin contained in the waste plastic raw material, the waste plastic raw material may be pretreated before being supplied to the thermal decomposition apparatus. Examples of the pretreatment include sorting treatment, crushing treatment, washing treatment, drying treatment, melting treatment, and dechlorination treatment. The sorting treatment is a treatment of sorting plastics containing polyolefin from the waste plastic raw material. The crushing treatment is a treatment of crushing the sorted plastic. The washing treatment is a treatment of washing the crushed plastic. The drying treatment is a treatment of drying the washed plastic. The melting treatment is a treatment of heating the plastic to make it liquid. The dechlorination treatment is a treatment of removing chlorine contained in the plastic.

[0042] The content of the polyolefin in the pretreated waste plastic raw material is preferably 80% by mass or more, more preferably 85% by mass or more, and still more preferably 90% by mass or more, based on 100% by mass of the waste plastic raw material.

[0043] The hydrocarbon stream according to the present embodiment contains hydrocarbons. The hydrocarbon stream may optionally contain oxygen-containing compounds, optionally contain nitrogen-containing compounds, optionally contain sulfur-containing compounds, and may optionally contain chlorine-containing compounds.

[0044] The hydrocarbons may comprise light hydrocarbons having less than 20 carbon atoms and heavy hydrocarbons having 20 or more carbon atoms. Examples of the light hydrocarbons include alkanes such as methane, ethane and propane; olefins such as ethylene, propylene and butene; diolefins such as butadiene; aromatic hydrocarbons such as benzene, toluene and xylene; cycloalkanes such as cyclohexane; and the like. From the viewpoint of improving the olefin yield in the method for producing olefins, the hydrocarbon stream preferably contains the olefin as said light hydrocarbon.

[0045] Examples of the oxygen-containing compounds include organic compounds having an oxygen functional group such as a carboxyl group, a hydroxyl group or an ether group, carbon dioxide, carbon monoxide, and the like. Examples of the nitrogen-containing compounds include organic compounds having a nitrogen functional group such as an amino group or an isocyanate group, nitrogen ring compounds, nitric oxide, nitrogen dioxide, and the like. Examples of the sulfur-containing compounds include organic compounds having a sulfur functional group such as a thiol group, a thioether group or a sulfonyl group, sulfur ring compounds, hydrogen sulfide, and the like. Examples of the chlorine-containing compounds include chlorine-containing alkanes such as methyl chloride and chloroform, chlorine-containing aromatic compounds, and the like.

[0046] In said pyrolysis step, the hydrocarbon stream may be vaporized or liquefied. In said pyrolysis step, the hydrocarbon stream is preferably liquefied. In the pyrolysis step, liquefying the hydrocarbon stream facilitates transportation of the hydrocarbon stream, so the pyrolysis step and the steps downstream of the pyrolysis step can be performed at different locations from each other. That is, in the method for producing olefins according to the present embodiment, the pyrolysis step and the steps downstream of the pyrolysis step may be performed intermittently.

[0047] In the pyrolysis step, at least a portion of the pyrolysis product may be liquefied. At least a portion of the liquefied pyrolysis product may be supplied back to the pyrolysis apparatus.

[0048] The heat source in the pyrolysis step may be heat generated by burning fuel, heat generated by an electric heater, or heat generated during exhaust gas treatment. Examples of the fuel include gaseous pyrolysis products contained in the pyrolysis product, and natural gas. The pyrolysis step may be carried out with one heat source alone, or with a combination of two or more heat sources.

[0049] In the aforementioned thermal decomposition step, the virgin plastic raw material containing polyolefin may be further thermally decomposed. The virgin plastic raw material means a polymer produced by a process including a polymerization step, a resin composition containing said polymer, or a plastic product using said polymer or resin composition that has not been used for any end use. The polyolefin contained in the virgin plastic raw material is the same as the polyolefin contained in the waste plastic raw material.

[0050] In the aforementioned pyrolysis step, the temperature at which pyrolysis is carried out is preferably 350°C to 800°C, more preferably 370°C to 600°C, and even more preferably 380°C to 550°C.

[0051] The yield of hydrocarbon flow is improved when the temperature of the pyrolysis process is within the above numerical range.

[0052] In the aforementioned pyrolysis step, the pressure at which the pyrolysis is carried out is preferably between atmospheric pressure - 50 kPaG and atmospheric pressure + 50 kPaG.

[0053] The thermal decomposition is accelerated when the pressure in the thermal decomposition process is within the above numerical range.

[0054] (Crude Olefin Production Process) The crude olefin production process is a process of supplying the hydrocarbon stream to a catalytic cracking apparatus, which decomposes hydrocarbons (also called catalytic cracking) by contacting a catalyst containing zeolite with hydrocarbons, in order to obtain crude olefins. The catalytic cracking involves a reaction in which a carbon-carbon single bond in one hydrocarbon molecule is cleaved, producing two olefin molecules having a carbon-carbon double bond. That is, the crude olefin includes olefins produced by the catalytic cracking of the hydrocarbons. In the crude olefin production process, the hydrocarbon stream obtained in the thermal decomposition process is supplied to the catalytic cracking apparatus.

[0055] The crude olefin production step can be carried out using the catalytic cracking apparatus described above. The crude olefin production step can preferably be carried out using at least one of a fluidized bed catalytic cracking apparatus and a moving bed catalytic cracking apparatus, and more preferably using a fluidized bed catalytic cracking apparatus.

[0056] The hydrocarbons and hydrocarbon streams in the crude olefin production step are the same as those described in the section on the thermal decomposition step.

[0057] Examples of catalysts containing zeolite include those containing beta-type zeolite, faujasite-type zeolite, L-type zeolite, ferrielite-type zeolite, mordenite-type zeolite, and MFI-type zeolite. Preferably, the zeolite-containing catalyst is one containing MFI-type zeolite. The catalyst containing MFI-type zeolite has an MFI structure.

[0058] The catalyst containing zeolite is preferably an H-type zeolite having hydrogen cations as acid sites.

[0059] A catalyst containing zeolite preferably further comprises at least one of silica and alumina. The catalyst containing zeolite may further contain at least one atom selected from the group consisting of titanium, chromium, manganese, iron, cobalt, nickel, copper, ruthenium, rhodium, palladium, silver, iridium, platinum, boron, nitrogen, sodium, potassium, magnesium, phosphorus, zinc, and gallium atoms.

[0060] The average particle size of the catalyst containing zeolite may be 50 μm or more and 120 μm or less, or 60 μm or more and 90 μm or less.

[0061] The average particle size of a zeolite-containing catalyst is determined based on volume-based particle size distribution measurement data obtained by laser diffraction according to the method specified in JIS R1629. In this particle size distribution measurement data, it refers to the particle size at which the cumulative number of particles from the smaller particle size side reaches 50% (also called the 50% equivalent particle size). The particle size defined in this way is generally called the "50% equivalent particle size" and is sometimes denoted as "D50".

[0062] By having the average particle size of the catalyst containing zeolite within the above numerical range, the proportion of unreacted hydrocarbon flow in the crude olefin production step can be reduced.

[0063] In the crude olefin production step, a fluidized bed, a mobile bed, or a stationary bed may be formed using a catalyst containing zeolite. Preferably, in the crude olefin production step, a fluidized bed is formed using a catalyst containing zeolite.

[0064] In the crude olefin production step, some of the hydrocarbons undergo polycondensation to form carbides (also called coke), and this coke may adhere to the catalyst surface. In one embodiment, the catalyst used in the crude olefin production step may be a catalyst on which the coke has adhered to the catalyst surface (also called a coke-containing catalyst).

[0065] The coke contains hazardous substances. The hazardous substances in the coke may be substances derived from at least one selected from the group consisting of nitrogen-containing compounds, sulfur-containing compounds, and chlorine-containing compounds. The coke may contain, as a hazardous substance, substances derived from at least one selected from the group consisting of nitrogen-containing compounds, sulfur-containing compounds, and chlorine-containing compounds.

[0066] In the crude olefin production step, the weight space velocity (WHSV) required for the catalytic decomposition of the catalyst containing zeolite is preferably 0.5 h. －１ More than 30 hours －１ The following, more preferably 1h －１ 15 hours －１ The following applies:

[0067] By having the weight space velocity (WHSV) required for catalytic cracking of the zeolite-containing catalyst in the crude olefin production step fall within the above numerical range, the proportion of unreacted hydrocarbon flow in the crude olefin production step can be reduced.

[0068] The crude olefin comprises an olefin, preferably an olefin, fuel oil, and fuel gas.

[0069] Examples of olefins included in the crude olefin include olefins having 2 to 4 carbon atoms. Examples of olefins having 2 to 4 carbon atoms include ethylene, propylene, 1-butene, 2-butene, and isobutene. The crude olefin according to this embodiment preferably contains at least one of ethylene and propylene.

[0070] The fuel oil contained in the crude olefin preferably includes at least a portion of light oil and heavy oil.

[0071] The fuel gas contained in the crude olefin preferably contains an alkane having 1 to 4 carbon atoms. Examples of alkanes having 1 to 4 carbon atoms include methane, ethane, propane, and butane.

[0072] The olefin content in the crude olefin is preferably 50% by mass or more and 85% by mass or less, and more preferably 55% by mass or more and 80% by mass or less. From the viewpoint of improving the yield of olefins in the method for producing olefins, the content of olefins having 2 to 4 carbon atoms in the crude olefin is preferably 45% by mass or more and 80% by mass or less, and more preferably 50% by mass or more and 75% by mass or less.

[0073] The fuel oil content in the crude olefin may be 2% by mass or more and 15% by mass or less, or 3% by mass or more and 10% by mass or less.

[0074] The fuel gas content in the crude olefin may be 2% by mass or more and 15% by mass or less, or 3% by mass or more and 10% by mass or less.

[0075] In the crude olefin production step, the temperature at which catalytic decomposition is carried out is preferably 400°C to 800°C, more preferably 450°C to 650°C, and even more preferably 500°C to 600°C.

[0076] By keeping the temperature of the crude olefin production step within the above numerical range, the yield of olefins in the olefin production method is improved.

[0077] (Separation step) The separation step is a step of separating olefins having 2 to 4 carbon atoms from the crude olefin. Preferably, the separation step is a step of further separating the fuel oil and the fuel gas from the crude olefin. In the separation step, the crude olefin obtained in the crude olefin production step is supplied to the separation apparatus described above.

[0078] The crude olefin and olefins having 2 to 4 carbon atoms, the fuel oil, and the fuel gas in the separation step are the same as those described in the section on the crude olefin production step.

[0079] The separation step can be carried out using the separation apparatus described above. The separation step can be carried out using one or more of the separation apparatuses. When the separation step is carried out using one or more of the separation apparatuses, the separation step can preferably be carried out using a distillation apparatus. When the separation step is carried out using more of the separation apparatuses, the separation step can preferably be carried out using at least two types of separation apparatuses selected from the group consisting of a distillation apparatus, a gas-liquid separator, an adsorption separator, a membrane separator, and a washing apparatus.

[0080] (Catalyst regeneration process) The catalyst regeneration process involves using a catalyst regeneration device that regenerates the catalyst by heating to regenerate the catalyst used in the crude olefin production process, and returning the regenerated catalyst to the catalytic cracking device.

[0081] The catalyst regeneration step may be a step in which the catalyst is regenerated by burning off the coke adhering to the catalyst surface by heating, thereby removing the coke from the catalyst surface. In the catalyst regeneration step, preferably, the coke-containing catalyst generated in the crude olefin production step is supplied to the catalyst regeneration device.

[0082] In the catalyst regeneration process, exhaust gas is generated when the catalyst is regenerated. This exhaust gas is generated by burning coke and other materials adhering to the catalyst surface. This exhaust gas is supplied to an exhaust gas treatment device, which will be described later.

[0083] The exhaust gas generated by the catalytic regeneration device contains the harmful substances. The harmful substances in the exhaust gas may be substances derived from at least one selected from the group consisting of nitrogen-containing compounds, sulfur-containing compounds, and chlorine-containing compounds. The exhaust gas generated by the catalytic regeneration device may contain, as harmful substances, substances derived from at least one selected from the group consisting of nitrogen-containing compounds, sulfur-containing compounds, and chlorine-containing compounds.

[0084] The temperature of the catalyst regeneration apparatus in the catalyst regeneration step is preferably 500°C to 750°C, more preferably 600°C to 730°C, and even more preferably 650°C to 700°C.

[0085] The temperature of the catalyst regeneration apparatus in the catalyst regeneration process is the temperature inside the catalyst regeneration apparatus. That is, the temperature of the catalyst regeneration apparatus in the catalyst regeneration process is a measurement value obtained using a thermometer or thermocouple placed inside the catalyst regeneration apparatus.

[0086] In the catalyst regeneration step, a fluidized bed, a mobile bed, or a stationary bed may be formed using the catalyst used in the crude olefin step. Preferably, in the catalyst regeneration step, a fluidized bed is formed using the catalyst used in the crude olefin step.

[0087] In one embodiment, in the crude olefin production step, a fluidized bed is formed by a catalyst containing zeolite, and in the catalyst regeneration step, a fluidized bed is formed by the catalyst used in the crude olefin production step. By forming a fluidized bed with the catalyst in the crude olefin production step and the catalyst regeneration step, the catalyst can reciprocate between the catalytic cracking apparatus and the catalyst regeneration apparatus.

[0088] In the catalyst regeneration step, the residence time for regenerating the catalyst used in the crude olefin step is preferably 60 seconds or more and 3600 seconds or less, and more preferably 120 seconds or more and 1800 seconds or less.

[0089] By ensuring that the residence time for regenerating the catalyst used in the crude olefin step in the catalyst regeneration step is within the above numerical range, the catalyst can be regenerated while suppressing catalyst degradation.

[0090] (Exhaust gas treatment process) The exhaust gas treatment process is a process of heating the exhaust gas generated by the catalyst regeneration device using an exhaust gas treatment device to burn and decompose harmful substances. In the exhaust gas treatment process, by heating the exhaust gas, harmful substances contained in the exhaust gas are burned and decomposed, rendering the exhaust gas harmless. In the exhaust gas treatment process, by heating the exhaust gas, substances derived from at least one selected from the group consisting of nitrogen-containing compounds, sulfur-containing compounds, and chlorine-containing compounds may be burned and decomposed as harmful substances contained in the exhaust gas, rendering the exhaust gas harmless. In the exhaust gas treatment process, the harmless exhaust gas is released into the atmosphere.

[0091] From the viewpoint of further reducing the concentration of harmful substances in the exhaust gas, the exhaust gas treatment process may pass the heated exhaust gas through the filter, the adsorption tower, or the washing tower.

[0092] The exhaust gas treatment process may obtain heat by passing the heated exhaust gas through the heat exchanger. This heat may be used to generate steam or to heat air.

[0093] The exhaust gas treatment step can be carried out using the exhaust gas treatment device described above. Preferably, the exhaust gas treatment step can be carried out using a direct combustion type exhaust gas treatment device.

[0094] The temperature of the exhaust gas treatment device in the exhaust gas treatment step is higher than the temperature of the catalyst regeneration device in the catalyst regeneration step. The temperature of the exhaust gas treatment device in the exhaust gas treatment step is preferably 800°C or higher and 900°C or lower, more preferably 810°C or higher and 880°C or lower, and even more preferably 820°C or higher and 850°C or lower.

[0095] The temperature of the exhaust gas treatment apparatus in the exhaust gas treatment process is the temperature inside the exhaust gas treatment apparatus. That is, the temperature of the exhaust gas treatment apparatus in the exhaust gas treatment process is a measurement value obtained using a thermometer or thermocouple placed inside the exhaust gas treatment apparatus.

[0096] The exhaust gas treatment step may involve supplying fuel and air to the exhaust gas treatment device and heating the exhaust gas by burning the fuel, heating the exhaust gas with a heated heat storage material, or heating a gas obtained by mixing the air supplied to the exhaust gas treatment device with the exhaust gas using a heated heat storage material. Examples of fuel include fuel oil and fuel gas. In the exhaust gas treatment step, the fuel oil and fuel gas obtained in the separation step may be supplied to the exhaust gas treatment device. Preferably, in the exhaust gas treatment step, at least a portion of the fuel oil and fuel gas is supplied to the exhaust gas treatment device and used as fuel, and more preferably, at least a portion of the fuel oil and fuel gas is supplied to the exhaust gas treatment device and burned to be used as fuel.

[0097] In one embodiment of the olefin production method according to this embodiment, the separation step is a step of further separating fuel oil and fuel gas from the crude olefin, and in the exhaust gas treatment step, at least a portion of the fuel oil and fuel gas is supplied to the exhaust gas treatment device and used as fuel.

[0098] The residence time of the exhaust gas in the exhaust gas treatment apparatus in the exhaust gas treatment step is preferably 2 seconds or more and 10 seconds or less, more preferably 3 seconds or more and 8 seconds or less, and even more preferably 4 seconds or more and 6 seconds or less.

[0099] The olefin production method according to this embodiment, when implemented in the manner described above, can suppress catalyst degradation while treating harmful substances contained in exhaust gas during catalytic cracking using waste plastic raw materials.

[0100] The method for producing olefins according to this embodiment includes: a thermal decomposition step of obtaining a hydrocarbon flow by thermal decomposing a waste plastic raw material containing polyolefin; a crude olefin production step of obtaining crude olefins by supplying the hydrocarbon flow to a catalytic cracking apparatus that decomposes hydrocarbons by contacting a catalyst containing zeolite with hydrocarbons; a separation step of separating olefins having 2 to 4 carbon atoms from the crude olefins; a catalyst regeneration step of regenerating the catalyst used in the crude olefin production step using a catalyst regeneration apparatus that regenerates the catalyst by heating, and returning the regenerated catalyst to the catalytic cracking apparatus; and an exhaust gas treatment step of heating the exhaust gas generated in the catalyst regeneration apparatus using an exhaust gas treatment apparatus to burn and decompose harmful substances, wherein the temperature of the exhaust gas treatment apparatus in the exhaust gas treatment step is higher than the temperature of the catalyst regeneration apparatus in the catalyst regeneration step.

[0101] In the olefin production method described above, the temperature of the exhaust gas treatment device in the exhaust gas treatment step is higher than the temperature of the catalyst regeneration device in the catalyst regeneration step. As a result, in the catalyst regeneration step, regeneration treatment is performed at a temperature that can suppress catalyst degradation, while in the exhaust gas treatment step, exhaust gas that could not be treated in the catalyst regeneration step can be treated.

[0102] The method for producing the olefin is such that the separation step further separates fuel oil and fuel gas from the crude olefin, and in the exhaust gas treatment step, at least a portion of the fuel oil and fuel gas is supplied to the exhaust gas treatment device and used as fuel.

[0103] The olefin production method, with this configuration, allows for the supply of at least a portion of the fuel oil and fuel gas to the exhaust gas treatment device and its use as fuel. This enables the heat source required by the exhaust gas treatment device to be supplemented by the by-products generated by catalytic cracking, thereby suppressing energy loss.

[0104] In the method for producing the olefin, the temperature of the catalyst regeneration apparatus in the catalyst regeneration step is 500°C or higher and 750°C or lower.

[0105] With this configuration, the olefin production method allows the catalyst to be sufficiently heated and regenerated during the catalyst regeneration process because the temperature of the catalyst regeneration apparatus is 500°C or higher. Furthermore, by keeping the temperature of the catalyst regeneration apparatus below 750°C, excessive heating of the catalyst can be avoided, and catalyst degradation can be suppressed.

[0106] In the method for producing the olefin, the temperature of the exhaust gas treatment device in the exhaust gas treatment step is 800°C or higher and 900°C or lower.

[0107] With the above-mentioned olefin manufacturing method, the exhaust gas treatment process can be sufficiently treated because the temperature of the exhaust gas treatment device is 800°C or higher. Furthermore, the deterioration of the exhaust gas treatment device can be suppressed because the temperature of the exhaust gas treatment device is 900°C or lower.

[0108] The method for producing the olefin is such that the residence time of the exhaust gas in the exhaust gas treatment device during the exhaust gas treatment step is 2 seconds or more and 10 seconds or less.

[0109] With this configuration, the olefin manufacturing method allows for sufficient combustion and decomposition of harmful substances in the exhaust gas during the exhaust gas treatment process, as the residence time of the exhaust gas in the exhaust gas treatment device is 2 seconds or more. Furthermore, if the residence time of the exhaust gas in the exhaust gas treatment device is 10 seconds or less, the process fluidity in the exhaust gas treatment process is improved.

[0110] <<Implementation Steps According to the First Embodiment>> The implementation steps according to the first embodiment of the present invention will be described below. The present invention is not limited to the following embodiments. Items described in the embodiments of the method for producing olefins will not be repeated.

[0111] An implementation step according to the first embodiment is an implementation step for carrying out the above-described method for producing an olefin, and includes the thermal decomposition step.

[0112] The implementation process according to the first embodiment, when carried out in the manner described above, can suppress catalyst degradation while treating harmful substances contained in exhaust gas during catalytic cracking using waste plastic raw materials.

[0113] <<Implementation Steps According to the Second Embodiment>> The implementation steps according to the second embodiment of the present invention will now be described. The present invention is not limited to the following embodiments. Items described in the first embodiment of the olefin manufacturing method and implementation steps will not be repeated.

[0114] The implementation steps according to the second embodiment are implementation steps for carrying out the above-described method for producing olefins, and include the crude olefin production step, the catalyst regeneration step, and the exhaust gas treatment step.

[0115] The implementation process according to the second embodiment, when carried out in the manner described above, can suppress catalyst degradation while treating harmful substances contained in exhaust gas during catalytic cracking using waste plastic raw materials.

[0116] <<Implementation Steps According to the Third Embodiment>> The implementation steps according to the third embodiment of the present invention will be described below. The present invention is not limited to the following embodiments. Items described in the first and second embodiments will not be repeated.

[0117] An implementation step according to the third embodiment is an implementation step for carrying out the above-described method for producing an olefin, and includes the separation step.

[0118] The implementation process according to the third embodiment, when carried out in the manner described above, can suppress catalyst degradation while treating harmful substances contained in exhaust gas during catalytic cracking using waste plastic raw materials.

[0119] The present invention includes the following embodiments.

[0120] [1] A method for producing olefins, comprising: a thermal decomposition step of thermally decomposing a waste plastic raw material containing polyolefin to obtain a hydrocarbon flow; a crude olefin production step of supplying the hydrocarbon flow to a catalytic cracking apparatus that decomposes hydrocarbons by contacting a catalyst containing zeolite with hydrocarbons to obtain crude olefins; a separation step of separating olefins having 2 to 4 carbon atoms from the crude olefins; a catalyst regeneration step of regenerating the catalyst used in the crude olefin production step using a catalyst regeneration apparatus that regenerates the catalyst by heating, and returning the regenerated catalyst to the catalytic cracking apparatus; and an exhaust gas treatment step of heating the exhaust gas generated in the catalyst regeneration apparatus using an exhaust gas treatment apparatus to burn and decompose harmful substances, wherein the temperature of the exhaust gas treatment apparatus in the exhaust gas treatment step is higher than the temperature of the catalyst regeneration apparatus in the catalyst regeneration step. [2] The method for producing olefins according to [1], wherein the separation step is a step of further separating fuel oil and fuel gas from the crude olefins, and in the exhaust gas treatment step, at least a portion of the fuel oil and fuel gas are supplied to the exhaust gas treatment apparatus for use as fuel. [3] The method for producing an olefin according to [1] or [2], wherein the temperature of the catalyst regeneration apparatus in the catalyst regeneration step is 500°C or more and 750°C or less. [4] The method for producing an olefin according to any one of [1] to [3], wherein the temperature of the exhaust gas treatment apparatus in the exhaust gas treatment step is 800°C or more and 900°C or less. [5] The method for producing an olefin according to any one of [1] to [4], wherein the residence time of the exhaust gas in the exhaust gas treatment apparatus in the exhaust gas treatment step is 2 seconds or more and 10 seconds or less. [6] An implementation step for carrying out the method for producing an olefin according to any one of [1] to [5], the implementation step including the pyrolysis step. [7] An implementation step for carrying out the method for producing an olefin according to any one of [1] to [5], the implementation step including the crude olefin production step, the catalyst regeneration step, and the exhaust gas treatment step. [8] An implementation step for carrying out the method for producing an olefin according to any one of [1] to [5], the implementation step including the separation step.

[0121] It should be noted that the method for producing olefins according to the present invention is not limited to the embodiments described above, and various modifications are possible without departing from the spirit of the present invention. Furthermore, configurations, methods, etc., of embodiments other than those described above may be arbitrarily adopted and combined.

Claims

1. A method for producing olefins, comprising: a thermal decomposition step of thermally decomposing a waste plastic raw material containing polyolefin to obtain a hydrocarbon flow; a crude olefin production step of supplying the hydrocarbon flow to a catalytic cracking apparatus that decomposes hydrocarbons by contacting a catalyst containing zeolite with hydrocarbons to obtain crude olefins; a separation step of separating olefins having 2 to 4 carbon atoms from the crude olefins; a catalyst regeneration step of regenerating the catalyst used in the crude olefin production step using a catalyst regeneration apparatus that regenerates the catalyst by heating, and returning the regenerated catalyst to the catalytic cracking apparatus; and an exhaust gas treatment step of heating the exhaust gas generated in the catalyst regeneration apparatus using an exhaust gas treatment apparatus to burn and decompose harmful substances, wherein the temperature of the exhaust gas treatment apparatus in the exhaust gas treatment step is higher than the temperature of the catalyst regeneration apparatus in the catalyst regeneration step.

2. The method for producing an olefin according to claim 1, wherein the separation step is a step of further separating fuel oil and fuel gas from the crude olefin, and in the exhaust gas treatment step, at least a portion of the fuel oil and fuel gas is supplied to the exhaust gas treatment device and used as fuel.

3. The method for producing an olefin according to claim 1, wherein the temperature of the catalyst regeneration apparatus in the catalyst regeneration step is 500°C or higher and 750°C or lower.

4. The method for producing an olefin according to claim 1, wherein the temperature of the exhaust gas treatment device in the exhaust gas treatment step is 800°C or higher and 900°C or lower.

5. The method for producing an olefin according to claim 1, wherein the residence time of the exhaust gas in the exhaust gas treatment apparatus in the exhaust gas treatment step is 2 seconds or more and 10 seconds or less.

6. An implementation step for carrying out the method for producing an olefin according to claim 1, comprising the thermal decomposition step.

7. An implementation step for carrying out the method for producing an olefin according to claim 1, comprising the crude olefin production step, the catalyst regeneration step, and the exhaust gas treatment step.

8. An implementation step for carrying out the method for producing an olefin according to claim 1, comprising the separation step.