Method for producing olefins

Abstract

The present invention aims to provide a method for producing olefins using waste plastic raw materials, which enables sufficient catalyst regeneration while suppressing catalyst degradation. [Solution] 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 hot air generation step of generating hot air containing oxygen gas using a hot air generator; and a catalyst regeneration step of supplying the hot air to a catalyst regeneration apparatus that regenerates a catalyst by heating, regenerating the catalyst used in the crude olefin production step with the hot air, and returning the regenerated catalyst to the catalytic cracking apparatus.

Description

Technical Field

[0001] The present invention relates to a method for producing olefins.

Background Art

[0002] Plastic products are made from petrochemical products obtained, for example, by a method of decomposing hydrocarbons derived from crude oil. Although there are many such decomposition methods, examples of the decomposition method using a catalyst include fluid catalytic cracking. In fluid catalytic cracking, hydrocarbon oil is catalytically cracked using a catalyst containing zeolite or the like, and petrochemical products, fuel oil, etc. are obtained by separation and purification.

[0003] In fluid catalytic cracking as described above, high molecular weight components or aromatic components such as heavy oil contained in crude oil are polycondensed to form carbides (also referred to as coke), and it is known that the coke is generated on the catalyst surface and deteriorates the catalyst activity. Therefore, in fluid catalytic cracking, in order to maintain the catalyst activity, a process of regenerating the catalyst (also referred to as a catalyst regeneration process) is carried out by burning the coke generated on the catalyst surface to remove the coke from the catalyst (see Patent Document 1). In the catalyst regeneration process, once the coke starts to burn, the coke itself serves as fuel and the combustion continues, so there is no need to supplement additional fuel or a heat source.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Incidentally, the recycling and reuse of plastics are attracting attention from the perspective of resource recovery. For example, reuse, material recycling, and chemical recycling are being carried out to recycle waste plastics. Chemical recycling, in particular, has the potential to overcome the limitations of performance degradation caused by recycling, as it can chemically decompose plastics and regenerate them into petrochemical raw materials.

[0006] However, when catalytic cracking is performed using hydrocarbon flow obtained by thermal decomposition of waste plastic raw materials, the amount of coke produced is small due to the low content of high molecular weight or aromatic components in the waste plastic, resulting in insufficient fuel in the catalyst regeneration process and inadequate catalyst regeneration. Furthermore, supplying additional fuel to the catalyst regeneration process may cause localized combustion, potentially degrading the catalyst.

[0007] In view of the above-mentioned problems, the present invention aims to provide a method for producing olefins in catalytic cracking using waste plastic raw materials, which enables sufficient catalyst regeneration while suppressing catalyst degradation. [Means for solving the problem]

[0008] The method for producing olefins according to the present invention is: A thermal decomposition process to obtain a hydrocarbon flow by thermally decomposing waste plastic raw materials containing polyolefins, A crude olefin production step involves supplying the hydrocarbon stream to a catalytic cracking apparatus that decomposes hydrocarbons by contacting a catalyst containing zeolite with hydrocarbons to obtain crude olefins, A separation step for separating olefins having 2 to 4 carbon atoms from the crude olefin, A hot air generation process in which a hot air generator is used to generate hot air containing oxygen gas, The catalyst regeneration process includes supplying hot air to a catalyst regeneration device that regenerates a catalyst by heating, regenerating the catalyst used in the crude olefin production process with the hot air, and returning the regenerated catalyst to the catalytic cracking device. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a method for producing olefins in catalytic cracking using waste plastic raw materials, which enables sufficient catalyst regeneration while suppressing catalyst degradation. [Modes for carrying out the invention]

[0010] The following describes a method for producing olefins according to embodiments of the present invention. The present invention is not limited to the following embodiments.

[0011] 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 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 hot air generation step of generating hot air containing oxygen gas using a hot air generator; and a catalyst regeneration step of supplying the hot air to a catalyst regeneration apparatus that regenerates the catalyst by heating, regenerating the catalyst used in the crude olefin production step with the hot air, and returning the regenerated catalyst to the catalytic cracking apparatus.

[0012] 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 is A pyrolysis apparatus that obtains a hydrocarbon flow by thermally decomposing waste plastic raw materials containing polyolefins, A catalytic cracking apparatus is provided to which the hydrocarbon stream is supplied, and a catalyst containing zeolite is brought into contact with the hydrocarbons in the hydrocarbon stream to decompose the hydrocarbons and obtain crude olefins. A separation apparatus for separating olefins having 2 to 4 carbon atoms from the crude olefin, A hot air generator that generates hot air containing oxygen gas, A catalyst regeneration device is provided to which hot air generated by the hot air generator is supplied, and which regenerates the catalyst containing zeolite used in the catalytic cracking device by heating with the hot air as the heat source, and returns the regenerated catalyst to the catalytic cracking device. It is equipped with.

[0013] [Pyrolysis equipment] 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.

[0014] 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 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.

[0015] The internal pressure of the pyrolysis apparatus is preferably between atmospheric pressure - 50 kPaG and atmospheric pressure + 50 kPaG.

[0016] The pyrolysis device may have at least one of a reflux device and a condenser. The reflux device and the condenser liquefy at least a part of the pyrolyzate. The pyrolysis device may have a pipe connecting the reaction tank and at least one of the reflux device and the condenser to supply at least a part of the liquefied pyrolyzate back to the reaction tank. The pyrolysis device may have a plurality of reflux devices and may have a plurality of condensers.

[0017] The pyrolysis device may heat the waste plastic raw material with any heat source. Examples of the heat source include heat generated by burning fuel, heat generated by an electric heater, heat generated during exhaust gas treatment, etc. Examples of the fuel include gaseous pyrolyzate contained in the pyrolyzate and other natural gas, etc. The pyrolysis device may use one kind of the heat source alone or may use a combination of two or more kinds of the heat sources.

[0018] [Catalytic cracking device] The catalytic cracking device is a device in which the hydrocarbon stream is supplied, the catalyst containing zeolite is brought into contact with the hydrocarbon in the hydrocarbon stream to decompose the hydrocarbon, and the crude olefin described later is obtained. The hydrocarbon is the hydrocarbon contained in the hydrocarbon stream obtained by the pyrolysis device. The crude olefin obtained by the catalytic cracking device is supplied to the separation device described later.

[0019] Examples of the catalytic cracking device include a fluidized bed catalytic cracking device, a moving bed catalytic cracking device, a fixed bed catalytic cracking device, etc. The fluidized bed catalytic cracking device is a device in which the hydrocarbon is decomposed by the contact of the fluidized particulate catalyst with the hydrocarbon. The moving bed catalytic cracking device is a device in which the hydrocarbon is decomposed by the contact of the granular catalyst with the hydrocarbon while moving from the upper part to the lower part in the device. The catalytic cracking device may be used alone or two or more kinds may be combined and connected in parallel or in series. The catalytic cracking device is preferably at least one of a fluidized bed catalytic cracking device and a moving bed catalytic cracking device, and more preferably a fluidized bed catalytic cracking device.

[0020] [Separation device] The separation device is a device for separating olefins having 2 to 4 carbon atoms from the crude olefin. The separation device may be a device for further separating fuel oil and fuel gas from the crude olefin. That is, the separation device may be a device for separating olefins having 2 to 4 carbon atoms, fuel oil, and fuel gas from the crude olefin. The olefins having 2 to 4 carbon atoms obtained by the separation device may be used as various petrochemical raw materials. The fuel oil and fuel gas obtained by the separation device may be supplied to a hot air generation device described later and used as fuel.

[0021] Examples of the separation device include a distillation device, a gas-liquid separation device, an adsorption separation device, a membrane separation device, a cleaning device, and the like. The separation device may be used alone or in combination of two or more kinds, connected in parallel or in series. When the separation device is used alone, the separation device is preferably a distillation device. When a plurality of the separation devices are used, the plurality of the separation devices are preferably at least two kinds selected from the group consisting of a distillation device, a gas-liquid separation device, an adsorption separation device, a membrane separation device, and a cleaning device.

[0022] [Hot air generation device] The hot air generation device is a device for generating hot air containing oxygen gas. The hot air generated by the hot air generation device is supplied to a catalyst regeneration device described later and used as a heat source for regenerating the catalyst.

[0023] Examples of the hot air generating devices include direct combustion type hot air generating devices and indirect heating type hot air generating devices. The direct combustion type hot air generating device is a device that uses combustion gas generated by burning fuel and air heated by the combustion gas to produce hot air. The indirect heating type hot air generating device is a device that generates hot air by heating air supplied to the inside of the device with an external heat source via a heat exchanger. As the heat source, for example, heat from burning fuel, heat generated by an electric heater, steam, etc., can be used. The hot air generating devices may be used individually, or two or more may be combined and connected in parallel or in series. The hot air generating device is preferably the direct combustion type hot air generating device.

[0024] The hot air generator may be supplied with oxygen gas from an external source, or it may be supplied with air whose oxygen concentration has been increased by an oxygen enrichment device.

[0025] [Catalyst regeneration device] The catalyst regeneration device is supplied with hot air generated by the hot air generator, and regenerates the catalyst containing zeolite used in the catalytic cracking device by heating with the hot air as the heat source, 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.

[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] 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 hot air generation step, and a catalyst regeneration step.

[0028] (pyrolysis process) The aforementioned pyrolysis step is a step of obtaining a hydrocarbon flow by pyrolysis of a waste plastic raw material containing polyolefin. More specifically, the pyrolysis step is a step of obtaining a hydrocarbon flow from a pyrolysis product obtained by pyrolysis of a waste plastic raw material containing polyolefin. The pyrolysis step 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 pyrolysis step contains hydrocarbons. In the pyrolysis step, pyrolysis residue may be generated from the waste plastic raw material.

[0029] 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.

[0030] The aforementioned waste plastic raw materials refer to plastic products that have been used for some end-use purpose.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] Examples of copolymers containing monomer units derived from olefins include propylene copolymers containing monomer units derived from propylene. Examples of such propylene copolymers include propylene-ethylene copolymers, propylene-1-butene copolymers, propylene-1-hexene copolymers, propylene-1-octene copolymers, propylene-ethylene-1-butene copolymers, propylene-ethylene-1-hexene copolymers, and propylene-ethylene-1-octene copolymers. The propylene copolymer may be a random copolymer or a heterophagic propylene polymerization material.

[0036] The aforementioned waste plastic raw material may also contain polymer components other than the polyolefin. Examples of polymer components other than polyolefin include chlorinated polyethylene, polyvinyl chloride (PVC), polyvinylidene chloride (PVDC), polyethylene terephthalate (PET), polybutylene terephthalate, polystyrene, nylon 66, and the like.

[0037] From the viewpoint of increasing the polyolefin content in the waste plastic raw material, the waste plastic raw material may be pre-treated before being supplied to the pyrolysis apparatus. Examples of such pre-treatment include sorting, crushing, washing, drying, melting, and dechlorination. The sorting process is a process of sorting plastics containing polyolefins from the waste plastic raw material. The crushing process is a process of crushing the sorted plastics. The washing process is a process of washing the crushed plastics. The drying process is a process of drying the washed plastics. The melting process is a process of heating the plastics to make them liquid. The dechlorination process is a process of removing chlorine contained in the plastics.

[0038] The polyolefin content in the pre-treated waste plastic raw material is preferably 80% by mass or more, more preferably 85% by mass or more, and even more preferably 90% by mass or more, based on 100% by mass of the waste plastic raw material.

[0039] The hydrocarbon stream according to this embodiment contains hydrocarbons. The hydrocarbon stream may also contain oxygen-containing compounds, nitrogen-containing compounds, sulfur-containing compounds, or chlorine-containing compounds.

[0040] The hydrocarbon may include 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; and cycloalkanes such as cyclohexane. From the viewpoint of improving the yield of olefins in the method for producing olefins, the hydrocarbon stream preferably contains the olefins as the light hydrocarbons.

[0041] Examples of the oxygen-containing compounds include organic compounds having oxygen functional groups such as carboxyl groups, hydroxyl groups, and ether groups, as well as carbon dioxide and carbon monoxide. Examples of the nitrogen-containing compounds include organic compounds having nitrogen functional groups such as amino groups and isocyanate groups, nitrogen ring compounds, nitric oxide, and nitrogen dioxide. Examples of the sulfur-containing compounds include organic compounds having sulfur functional groups such as thiol groups, thioether groups, and sulfonyl groups, sulfur ring compounds, and hydrogen sulfide. Examples of the chlorine-containing compounds include methyl chloride, chlorine-containing alkanes such as chloroform, and chlorine-containing aromatic compounds.

[0042] In the pyrolysis step, the hydrocarbon stream may be vaporized or liquefied. Preferably, in the pyrolysis step, the hydrocarbon stream is liquefied. Since the hydrocarbon stream is liquefied in the pyrolysis step, it is easy to transport the hydrocarbon stream, and therefore the pyrolysis step and the steps downstream therefrom can be carried out in different locations. That is, in the method for producing olefins according to this embodiment, the pyrolysis step and the steps downstream therefrom may be carried out intermittently.

[0043] 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.

[0044] 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 a single heat source, or with a combination of two or more heat sources.

[0045] 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.

[0046] 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.

[0047] The yield of hydrocarbon flow is improved when the temperature of the pyrolysis process is within the above numerical range.

[0048] In the aforementioned pyrolysis step, the pressure at which pyrolysis is carried out is preferably between atmospheric pressure - 50 kPaG and atmospheric pressure + 50 kPaG.

[0049] The thermal decomposition is accelerated when the pressure in the thermal decomposition process is within the above numerical range.

[0050] (Crude olefin production process) The crude olefin production step involves supplying a 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 a crude olefin. The catalytic cracking includes 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. In other words, the crude olefin includes olefins produced by the catalytic cracking of the hydrocarbons. In the crude olefin production step, the hydrocarbon stream obtained in the thermal decomposition step is supplied to the catalytic cracking apparatus.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] The catalyst containing the zeolite is preferably an H-type zeolite having hydrogen cations as acid sites.

[0055] 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.

[0056] 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 80 μm or less.

[0057] The average particle size of a catalyst containing zeolite 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 amount from the smallest particle size 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".

[0058] 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.

[0059] 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.

[0060] 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).

[0061] In the crude olefin production step, the weight-space velocity (WHSV) required for catalytic decomposition of the catalyst containing zeolite is preferably 0.5 h. -1 More than 30h -1 The following, more preferably 1h -1 15 hours -1 The following applies:

[0062] By ensuring that the residence time required for the catalytic cracking of the zeolite-containing catalyst in the crude olefin production step is within the above numerical range, the proportion of unreacted hydrocarbon flow in the crude olefin production step can be reduced.

[0063] The crude olefin comprises an olefin, preferably an olefin, fuel oil, and fuel gas.

[0064] 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.

[0065] The fuel oil contained in the crude olefin preferably includes at least a portion of light oil and heavy oil.

[0066] 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.

[0067] 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 olefin content 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.

[0068] 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.

[0069] 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.

[0070] 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.

[0071] 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.

[0072] (separation process) 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.

[0073] The crude olefin and olefins having 2 to 4 carbon atoms in the separation step, the fuel oil, and the fuel gas are the same as those described in the section on the crude olefin production step.

[0074] 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 distillation apparatuses, gas-liquid separators, adsorption separators, membrane separators, and washing apparatuses.

[0075] (Hot air generation process) The hot air generation step is a step of generating hot air containing oxygen gas using a hot air generator. The hot air generation step can be carried out using the hot air generator described above. Preferably, the hot air generation step can be carried out using the direct combustion type hot air generator.

[0076] The oxygen gas contained in the hot air may be the oxygen gas contained in the air supplied to the hot air generator, the oxygen gas contained in the air whose oxygen concentration has been increased by the oxygen enrichment device supplied to the hot air generator, or the oxygen gas supplied directly to the hot air generator.

[0077] The oxygen gas content in the hot air is preferably 3% by volume or more and 18% by volume or less, more preferably 4% by volume or more and 15% by volume or less, and even more preferably 5% by volume or more and 10% by volume or less.

[0078] The oxygen gas content in the hot air can be determined by measuring it using a zirconia oxygen sensor placed at the inlet of the catalyst regeneration device.

[0079] By keeping the oxygen gas content in the hot air within the above numerical range, the catalyst can be regenerated while suppressing its degradation.

[0080] The temperature of the hot air is preferably 300°C to 800°C, more preferably 400°C to 750°C, and even more preferably 500°C to 700°C.

[0081] The temperature of the hot air is the temperature at the inlet of the catalyst regeneration device. That is, the temperature of the hot air is a measurement value obtained using a thermometer or thermocouple placed at the inlet of the catalyst regeneration device.

[0082] By keeping the temperature of the hot air within the above numerical range, the catalyst can be regenerated while suppressing its deterioration.

[0083] The hot air generation step may generate the hot air using fuel, or it may generate the hot air by burning fuel. Examples of fuel include fuel oil and fuel gas. In the hot air generation step, the fuel oil and fuel gas obtained in the separation step may be supplied to the hot air generator. In the hot air generation step, preferably, at least a portion of the fuel oil and fuel gas is supplied to the hot air generator and used as fuel, and more preferably, at least a portion of the fuel oil and fuel gas is supplied to the hot air generator and burned and used as fuel.

[0084] 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 hot air generation step, at least a portion of the fuel oil and fuel gas is supplied to the hot air generator and used as fuel.

[0085] (Catalyst regeneration process) The catalyst regeneration step involves supplying hot air to a catalyst regeneration device that regenerates the catalyst by heating, regenerating the catalyst used in the crude olefin production step with the hot air, and returning the regenerated catalyst to the catalytic cracking device. In the catalyst regeneration step, the hot air generated in the hot air generation step is supplied to the catalyst regeneration device described above.

[0086] The hot air in the catalyst regeneration process is the same as that described in the section on the hot air generation process.

[0087] 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.

[0088] 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.

[0089] 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.

[0090] 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.

[0091] 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.

[0092] The olefin production method according to this embodiment, when implemented in the manner described above, enables sufficient catalyst regeneration while suppressing catalyst degradation in catalytic cracking using waste plastic raw materials.

[0093] 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 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 hot air generation step of generating hot air containing oxygen gas using a hot air generator; and a catalyst regeneration step of supplying the hot air to a catalyst regeneration apparatus that regenerates the catalyst by heating, regenerating the catalyst used in the crude olefin production step with the hot air, and returning the regenerated catalyst to the catalytic cracking apparatus.

[0094] The above-mentioned method for producing olefins, with this configuration, allows the catalyst to be sufficiently heated within the catalyst regeneration apparatus, regardless of the amount of coke generated in the crude olefin production process, by regenerating the catalyst using hot air in the catalyst regeneration apparatus. Furthermore, since the catalyst is heated with hot air, localized heating of the catalyst can be avoided, and deterioration of the catalyst due to excessive heating can be suppressed.

[0095] 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 hot air generation step, at least a portion of the fuel oil and fuel gas is supplied to the hot air generator and used as fuel.

[0096] In the aforementioned method for producing olefins, by supplying at least a portion of the fuel oil and fuel gas to a hot air generator and using it as fuel, the heat source of the hot air can be supplemented with by-products generated by catalytic cracking, thereby suppressing energy loss.

[0097] In the method for producing the olefin, the temperature of the hot air is 300°C or higher and 800°C or lower.

[0098] The above-mentioned method for producing olefins, with the hot air temperature being 300°C or higher, allows for sufficient heating and regeneration of the catalyst during the catalyst regeneration process. Furthermore, by keeping the hot air temperature below 800°C, excessive heating of the catalyst can be avoided, thereby suppressing catalyst degradation.

[0099] The method for producing the olefin is such that the oxygen gas content in the hot air is 3% by volume or more and 18% by volume or less.

[0100] The above-mentioned method for producing olefins, with such a configuration, allows for sufficient combustion of coke adhering to the catalyst during the catalyst regeneration process, thereby enabling sufficient catalyst regeneration, by ensuring that the oxygen gas content in the hot air is 3% by volume or more. Furthermore, by ensuring that the oxygen gas content in the hot air is 18% by volume or less, excessive combustion of coke adhering to the catalyst and excessive heating of the catalyst can be avoided, thereby suppressing catalyst degradation.

[0101] The present invention includes the following embodiments.

[0102] [1] A thermal decomposition process to obtain a hydrocarbon flow by thermally decomposing waste plastic raw materials containing polyolefins, A crude olefin production step involves supplying the hydrocarbon stream to a catalytic cracking apparatus that decomposes hydrocarbons by contacting a catalyst containing zeolite with hydrocarbons to obtain crude olefins, A separation step for separating olefins having 2 to 4 carbon atoms from the crude olefin, A hot air generation process in which a hot air generator is used to generate hot air containing oxygen gas, A catalyst regeneration process includes supplying hot air to a catalyst regeneration device that regenerates a catalyst by heating, regenerating the catalyst used in the crude olefin production process with the hot air, and returning the regenerated catalyst to the catalytic cracking device. A method for producing olefins. [2] The separation step is a step of further separating fuel oil and fuel gas from the crude olefin, In the hot air generation process, at least a portion of the fuel oil and fuel gas is supplied to the hot air generator and used as fuel. A method for producing the olefin described in [1]. [3] The temperature of the hot air is between 300°C and 800°C. A method for producing an olefin as described in [1] or [2]. [4] The oxygen gas content in the hot air is 3% by volume or more and 18% by volume or less. A method for producing an olefin as described in any one of [1] to [3].

[0103] 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 thermal decomposition process to obtain a hydrocarbon flow by thermally decomposing waste plastic raw materials containing polyolefins, A crude olefin production step involves supplying the hydrocarbon stream to a catalytic cracking apparatus that decomposes hydrocarbons by contacting a catalyst containing zeolite with hydrocarbons to obtain crude olefins, A separation step for separating olefins having 2 to 4 carbon atoms, fuel oil, and fuel gas from the crude olefin, A hot air generation process in which a hot air generator is used to generate hot air containing oxygen gas, The catalyst regeneration process includes supplying hot air to a catalyst regeneration device that regenerates a catalyst by heating, regenerating the catalyst used in the crude olefin production process with the hot air, and returning the regenerated catalyst to the catalytic cracking device, In the hot air generation process, the fuel oil and fuel gas are supplied to the hot air generator and used as fuel. A method for producing olefins.

2. The temperature of the hot air is between 300°C and 800°C. A method for producing an olefin according to claim 1.

3. The oxygen gas content in the hot air is 3% by volume or more and 18% by volume or less. A method for producing an olefin according to claim 1.

4. An implementation step for carrying out the method for producing an olefin according to Claim 1, Including the aforementioned thermal decomposition step, Implementation process.

5. An implementation step for carrying out the method for producing an olefin according to Claim 1, The process includes the crude olefin production step, the hot air generation step, and the catalyst regeneration step. Implementation process.

6. An implementation step for carrying out the method for producing an olefin according to Claim 1, Including the separation step, Implementation process.