Olefin production method and hydrogenated product production method

Abstract

Provided is an olefin production method comprising: a hydrogenation step for hydrogenating a hydrocarbon fluid containing olefin and obtained by thermally decomposing a waste plastic raw material containing polyolefin, while causing at least a portion of the olefin to remain, thereby obtaining a hydrogenated product; and a crude olefin generation step for using a catalyst containing zeolite to obtain crude olefin from the hydrogenated product. Also provided is a hydrogenated product production method used in a crude olefin generation step for using a catalyst containing zeolite to obtain crude olefin from a hydrogenated product, said method comprising a hydrogenation step for hydrogenating a hydrocarbon fluid containing olefin and obtained by thermally decomposing a waste plastic raw material containing polyolefin, while causing at least a portion of the olefin to remain, thereby obtaining a hydrogenated product.

Description

Method for producing olefins, and method for producing hydrogenation products Cross-reference of related applications

[0001] This application claims priority over Japanese Patent Application No. 2025-054635 and Japanese Patent Application No. 2026-015896, the disclosures thereof which are incorporated into the description of this application by reference.

[0002] This invention relates to a method for producing olefins and a method for producing hydrogenation products.

[0003] Plastic products are made from petrochemical products obtained by, for example, the decomposition of hydrocarbons derived from crude oil. While numerous decomposition methods exist, one example of a catalyst-based decomposition method is fluid catalytic cracking. In fluid catalytic cracking, a catalyst containing zeolite or similar material is used to catalytically crack hydrocarbon oil, followed by separation and purification to obtain petrochemical products, fuel oil, and other similar products.

[0004] In fluid catalytic cracking as described above, it is known that high molecular weight components such as heavy oil or aromatic components contained in crude oil undergo polycondensation to form carbides (also called coke), and that this coke forms on the catalyst surface, degrading catalytic activity. Therefore, in fluid catalytic cracking, the catalyst is regenerated and catalytic activity is maintained by burning off the coke formed on the catalyst surface to remove it (see Patent Document 1).

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

[0006] 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.

[0007] However, when catalytic cracking is performed using hydrocarbon streams obtained by thermally decomposing waste plastic raw materials, the thermal decomposition products of the waste plastic raw materials contain toxic substances such as chlorine-containing compounds that poison the catalyst used in catalytic cracking. This leads to a problem where the activity of the catalyst deteriorates regardless of the presence or absence of coke. Thermal decomposition and catalytic cracking of waste plastics are carried out sequentially, but if toxic substances are removed from the waste plastic raw materials before these processes are carried out, the concentration of olefins in the hydrocarbon stream of the raw materials used in catalytic cracking, which could increase the yield of olefins obtained in catalytic cracking, may decrease. As a result, the yield of olefins and other petrochemical raw materials may decrease.

[0008] In view of the above-mentioned problems, the present invention aims to provide a method for producing olefins and a method for producing hydrogenation products that suppress the decrease in olefin yield and reduce catalyst poisoning in catalytic cracking using waste plastic raw materials.

[0009] The present invention relates to a method for producing olefins, comprising: a hydrogenation step of obtaining a hydrogenation product by hydrogenating a hydrocarbon stream containing an olefin, obtained by thermally decomposing a waste plastic raw material containing a polyolefin, while leaving at least a portion of the olefin; and a crude olefin production step of obtaining a crude olefin from the hydrogenation product using a catalyst containing a zeolite.

[0010] The present invention relates to a method for producing a hydrogenation product used in a crude olefin production step to obtain a crude olefin from a hydrogenation product using a catalyst containing zeolite, and includes a hydrogenation step to obtain a hydrogenation product by hydrogenating a hydrocarbon stream containing olefin, obtained by thermally decomposing a waste plastic raw material containing polyolefin, while leaving at least a portion of the olefin intact.

[0011] The method for producing olefins according to the present invention includes a crude olefin production step in which crude olefins are obtained from the hydrogenation product obtained by the above-described method for producing hydrogenation products using a catalyst containing zeolite.

[0012] 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.

[0013] The method for producing olefins according to the first embodiment includes a hydrogenation step of obtaining a hydrogenation product by hydrogenating a hydrocarbon stream containing olefins, obtained by thermally decomposing a waste plastic raw material containing polyolefins, while leaving at least a portion of the olefins intact, and a crude olefin production step of obtaining crude olefins from the hydrogenation product using a catalyst containing zeolite.

[0014] The method for producing olefins according to the first embodiment may further include a thermal decomposition step of thermally decomposing a waste plastic raw material containing polyolefin to obtain a hydrocarbon flow containing olefin, and may further include a separation step of separating olefins having 2 to 4 carbon atoms from the crude olefin.

[0015] First, the apparatus for producing olefins used in the method for producing olefins according to the first embodiment will be described. The apparatus for producing olefins used in the first embodiment includes a hydrogenation apparatus that hydrogenates a hydrocarbon stream containing olefins, obtained by thermally decomposing waste plastic raw materials containing polyolefins, while leaving at least a portion of the olefins, to obtain a hydrogenation product, and a catalytic cracking apparatus that uses a catalyst containing zeolite to obtain crude olefins from the hydrogenation product.

[0016] The olefin production apparatus used in the first embodiment may further include a pyrolysis apparatus for pyrolyzing waste plastic raw materials containing polyolefins to obtain a hydrocarbon flow containing olefins, and may further include a separation apparatus for separating olefins having 2 to 4 carbon atoms from the crude olefin.

[0017] [Pyrolysis Apparatus] The pyrolysis apparatus is a device that pyrolyzes waste plastic raw materials containing polyolefins to obtain a hydrocarbon stream containing olefins. More specifically, the pyrolysis apparatus is a device that pyrolyzes waste plastic raw materials containing polyolefins to obtain pyrolysis products and obtains a hydrocarbon stream from the pyrolysis products. The pyrolysis apparatus has a reaction vessel for pyrolyzing the waste plastic raw materials. The hydrocarbon stream obtained from the pyrolysis apparatus is supplied to a hydrogenation apparatus, which will be described later.

[0018] 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.

[0019] The internal pressure of the pyrolysis apparatus is preferably between atmospheric pressure - 50 kPaG and atmospheric pressure + 50 kPaG.

[0020] 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 reaction vessel. The pyrolysis apparatus may have multiple refluxing devices and multiple condensers.

[0021] 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.

[0022] [Hydrogenation apparatus] The hydrogenation apparatus is a device that hydrogenates the hydrocarbon stream while leaving at least a portion of the olefin, thereby obtaining a hydrogenation product. The hydrogenation product obtained in the hydrogenation apparatus is supplied to a catalytic cracking apparatus, which will be described later.

[0023] Examples of the hydrogenation apparatus include a fixed-bed reactor, a fluidized-bed reactor, and a slurry-bed reactor. The hydrogenation apparatus may be used individually, or two or more may be combined and connected in parallel or in series. Preferably, the hydrogenation apparatus is at least one selected from the group consisting of a fixed-bed reactor, a fluidized-bed reactor, and a slurry-bed reactor.

[0024] The hydrogenation device may be supplied with a vaporized hydrocarbon stream, a liquefied hydrocarbon stream, or a mixed stream of a vaporized hydrocarbon stream and a liquefied hydrocarbon stream.

[0025] The hydrogenation apparatus may be an apparatus that hydrogenates the hydrocarbon stream while leaving at least a portion of the olefin, and then further washes it with water to obtain the hydrogenation product. The olefin production apparatus according to the first embodiment may further include a washing apparatus that washes the hydrogenation product obtained in the hydrogenation apparatus with water and supplies it to a catalytic cracking apparatus described later.

[0026] Hydrogen is supplied to the hydrogenation apparatus. Hydrogen may be supplied to the hydrogenation apparatus from an external source, or it may be supplied with hydrogen obtained from a separation apparatus described later.

[0027] [Catalytic Cracking Apparatus] The catalytic cracking apparatus is an apparatus that uses a catalyst containing zeolite to obtain crude olefins, described later, from the hydrogenation products. The catalytic cracking apparatus may also be an apparatus that receives the hydrogenation products, contacts the catalyst containing zeolite with the hydrocarbons in the hydrogenation products to decompose the hydrocarbons and obtain the crude olefins. The crude olefins obtained in the catalytic cracking apparatus may be supplied to a separation apparatus, described later.

[0028] 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.

[0029] [Separation apparatus] The separation apparatus is an apparatus for separating olefins having 2 to 4 carbon atoms from crude olefins. The separation apparatus may also be an apparatus for further separating hydrogen from crude olefins. That is, the separation apparatus may be an apparatus for separating olefins having 2 to 4 carbon atoms and hydrogen from crude olefins. The olefins having 2 to 4 carbon atoms obtained in the separation apparatus may be used as various petrochemical raw materials. The hydrogen obtained in the separation apparatus may be supplied to the hydrogenation apparatus and used for hydrogenation.

[0030] 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.

[0031] Next, a method for producing olefins according to the first embodiment will be described. The method for producing olefins according to the first embodiment includes a hydrogenation step and a crude olefin production step. The method for producing olefins according to the first embodiment may also include a thermal decomposition step and a separation 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 containing olefin. 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 containing olefin 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 olefins include propylene copolymers containing monomer units derived from propylene. Examples of said 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. Said propylene copolymer may be a random copolymer or may be a heterophasic propylene polymerization material.

[0040] Said waste plastic raw material may contain polymer components other than said polyolefins. Examples of polymer components other than said polyolefins 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 polyolefins contained in said waste plastic raw material, said waste plastic raw material may be pretreated before being supplied to said pyrolysis apparatus. Examples of said pretreatment include sorting treatment, crushing treatment, washing treatment, drying treatment, melting treatment, and dechlorination treatment. Said sorting treatment is a treatment of sorting plastics containing polyolefins from said waste plastic raw material. Said crushing treatment is a treatment of crushing the sorted plastics. Said washing treatment is a treatment of washing the crushed plastics. Said drying treatment is a treatment of drying the washed plastics. Said melting treatment is a treatment of heating plastics to turn them into a liquid state. Said dechlorination treatment is a treatment of removing chlorine contained in plastics.

[0042] The content of said polyolefin in said pretreated said 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 first embodiment contains hydrocarbons. The hydrocarbon stream may also contain oxygen-containing compounds, nitrogen-containing compounds, sulfur-containing compounds, or chlorine-containing compounds.

[0044] Examples of the 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. The hydrocarbon stream includes the olefins as hydrocarbons.

[0045] 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.

[0046] 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 the first embodiment, the pyrolysis step and the steps downstream therefrom may be carried out 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] (Hydrogenation process) The hydrogenation process involves hydrogenating a hydrocarbon stream containing olefin, obtained by thermally decomposing a waste plastic raw material containing polyolefin, while leaving at least a portion of the olefin, to obtain a hydrogenation product.

[0055] The hydrogenation step can be carried out using the hydrogenation apparatus described above. Preferably, the hydrogenation step can be carried out using at least one selected from the group consisting of a fixed-bed reactor, a fluidized-bed reactor, and a slurry-bed reactor.

[0056] The hydrocarbon stream contains the hydrocarbons described above. In one embodiment, the hydrocarbon stream according to the first embodiment contains a poisoning substance that reduces the activity of the catalyst used in the crude olefin production step. That is, the hydrogenation step may be a step of hydrogenating the poisoning substance contained in the hydrocarbon stream while leaving at least a portion of the olefin, in order to obtain a hydrogenation product.

[0057] The poisoning substance may be a substance derived from at least one selected from the group consisting of nitrogen-containing compounds, sulfur-containing compounds, oxygen-containing compounds, and chlorine-containing compounds. That is, the hydrogenation step may be a step of hydrogenating a substance derived from at least one selected from the group consisting of nitrogen-containing compounds, sulfur-containing compounds, oxygen-containing compounds, and chlorine-containing compounds contained in the hydrocarbon stream, while leaving at least a portion of the olefin, to obtain a hydrogenation product.

[0058] The nitrogen-containing compound, sulfur-containing compound, oxygen-containing compound, and chlorine-containing compound in the hydrogenation step are the same as those described in the section on the pyrolysis step.

[0059] The hydrogenation step hydrogenates a substance derived from at least one selected from the group consisting of nitrogen-containing compounds, sulfur-containing compounds, oxygen-containing compounds, and chlorine-containing compounds contained in the hydrocarbon stream, thereby decomposing these substances into ammonia, hydrogen chloride, hydrogen sulfide, water, etc., and the toxic substance can be easily removed from the hydrogenation product supplied to the catalytic cracking apparatus.

[0060] The hydrogenation step may involve hydrogenating the hydrocarbon flow using a hydrogenation catalyst.

[0061] The hydrogenation catalyst is not particularly limited. Examples of the hydrogenation catalyst include a catalyst comprising at least one support selected from the group consisting of alumina, silica, silica-alumina, zeolite, magnesia, and clay, and a metal. Preferably, the hydrogenation catalyst comprises at least one support selected from the group consisting of alumina, silica, silica-alumina, zeolite, magnesia, and clay, and a metal. Examples of the metal include molybdenum, nickel, cobalt, tungsten, palladium, platinum, and copper. Preferably, the metal is at least one selected from the group consisting of molybdenum, nickel, cobalt, tungsten, palladium, platinum, and copper.

[0062] If the hydrogenation catalyst contains a metal, the metal content, calculated on a metal element basis, is preferably 0.3% to 20% by mass, more preferably 0.5% to 15% by mass, and even more preferably 1% to 10% by mass, based on 100% by mass of the hydrogenation catalyst.

[0063] By keeping the metal content within the above numerical range, the hydrocarbon flow can be sufficiently hydrogenated while the olefin is not excessively hydrogenated, allowing a sufficient amount of the olefin to remain.

[0064] In the hydrogenation step, the hydrogenation catalyst may form a stationary layer, a fluidized layer, or a slurry bed. When the hydrogenation catalyst forms a stationary layer, the stationary layer is formed by a molded hydrogenation catalyst. The molded hydrogenation catalyst may be spherical, cylindrical, or ring-shaped.

[0065] When the hydrogenation catalyst forms a stationary layer, the outermost diameter of the molded hydrogenation catalyst is preferably 0.5 mm to 8 mm, and more preferably 0.8 mm to 5 mm. The outermost diameter of the molded hydrogenation catalyst refers to the distance between the furthest points on the surface of one molded hydrogenation catalyst. When the hydrogenation catalyst forms a fluidized bed or slurry bed, the particle size of the hydrogenation catalyst is preferably 10 μm to 500 μm, and more preferably 20 μm to 200 μm.

[0066] In the hydrogenation step, hydrogen is supplied to the hydrogenation apparatus. In the hydrogenation step, hydrogen may be supplied to the hydrogenation apparatus from an external source, or hydrogen obtained in the separation step described later may be supplied.

[0067] In the hydrogenation step, the hydrocarbon stream may be vaporized or liquefied. In the hydrogenation step, some of the hydrocarbon stream may be vaporized and other hydrocarbon streams may be liquefied.

[0068] In the hydrogenation step, the temperature at which hydrogenation is carried out is preferably 150°C to 300°C, and more preferably 170°C to 250°C.

[0069] By setting the hydrogenation temperature in the hydrogenation apparatus to 150°C, the hydrocarbon flow can be sufficiently hydrogenated. By setting the hydrogenation temperature in the hydrogenation apparatus to 300°C or lower, the olefin is not excessively hydrogenated, and a sufficient amount of the olefin can be retained.

[0070] In the hydrogenation step, the pressure used for hydrogenation is preferably 1 MPaG or more and 5 MPaG or less, and more preferably 1.2 MPaG or more and 3 MPaG or less.

[0071] By setting the hydrogenation pressure in the hydrogenation apparatus to 1 MPaG or higher, the hydrocarbon flow can be sufficiently hydrogenated. By setting the hydrogenation pressure in the hydrogenation apparatus to 5 MPaG or lower, the olefin is not excessively hydrogenated, and a sufficient amount of the olefin can be retained.

[0072] In the hydrogenation step, the ratio of the volume of hydrogen to the volume of the hydrocarbon stream is preferably 40 to 200, and more preferably 50 to 100. The "volume" of the hydrocarbon stream and the "volume" of hydrogen are used as values ​​converted to "volume at 0°C and 1 atmosphere".

[0073] By having a ratio of the volume of hydrogen to the volume of the hydrocarbon flow in the hydrogenation apparatus of 40 or more, the hydrocarbon flow can be sufficiently hydrogenated. By having a ratio of the volume of hydrogen to the volume of the hydrocarbon flow in the hydrogenation apparatus of 200 or less, the olefin is not excessively hydrogenated, and a sufficient amount of the olefin can be retained.

[0074] The liquid space velocity (LHSV) of the hydrocarbon flow in the hydrogenation apparatus is preferably 0.1h. －１ 6 hours －１ The following, and more preferably 0.5h －１ More than 3 hours －１ The following applies:

[0075] The liquid space velocity (LHSV) of the hydrocarbon flow in the hydrogenation apparatus is 6 h －１ The hydrocarbon flow can be sufficiently hydrogenated by the following: The liquid space velocity (LHSV) of the hydrocarbon flow in the hydrogenation apparatus is 0.1h. －１ As a result, the olefin is not excessively hydrogenated, and a sufficient amount of the olefin can be retained.

[0076] Preferably, the hydrogenation step involves hydrogenating the hydrocarbon stream and then washing it with water to obtain the hydrogenation product.

[0077] In the aforementioned washing, water may be used, or a basic aqueous solution may be used.

[0078] The olefin content in the hydrogenation product in the hydrogenation step is preferably 20% by mass or more, more preferably 25% by mass or more and 85% by mass or less, and even more preferably 30% by mass or more and 85% by mass or less.

[0079] The olefin content in the hydrogenation product in the hydrogenation process can be measured by type analysis standardized to JPI-5S-49. In this measurement, hydrocarbon components can be classified and quantified using HPLC into five categories: saturated components, olefin components, mono-ring aromatic components, di-ring aromatic components, and tri-ring or more aromatic components.

[0080] (Crude Olefin Production Step) The crude olefin production step is a step of obtaining a crude olefin from the hydrogenation product using a catalyst containing zeolite. The crude olefin production step may also be a step of supplying the hydrogenation product to a catalytic cracking apparatus that contacts the catalyst containing zeolite with the hydrocarbon in the hydrogenation product to decompose the hydrocarbon (also called catalytic cracking) to obtain a crude olefin. The catalytic cracking includes a reaction that cleaves a carbon-carbon single bond in one molecule of hydrocarbon and produces two molecules of olefin having a carbon-carbon double bond. That is, the crude olefin includes an olefin produced by the catalytic cracking of the hydrocarbon. In the crude olefin production step, the hydrogenation product obtained in the hydrogenation step is supplied to the catalytic cracking apparatus.

[0081] 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.

[0082] The hydrocarbons and hydrogenation products in the crude olefin production step are the same as those described in the sections on the thermal decomposition step and the hydrogenation step.

[0083] 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.

[0084] The catalyst containing zeolite is preferably an H-type zeolite having hydrogen cations as acid sites.

[0085] 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.

[0086] The amount of acid sites measured at 250 to 650°C by the ammonia thermal desorption method of the catalyst is preferably greater than 0 μmol / g and less than or equal to 800 μmol / g. The amount of acid sites measured at 250 to 650°C by the ammonia thermal desorption method of the catalyst may be 5 μmol / g or more, 10 μmol / g or more, 20 μmol / g or more, 30 μmol / g or more, 40 μmol / g or more, or 50 μmol / g or more. The amount of acid sites measured at 250 to 650°C by the ammonia thermal desorption method of the catalyst may be 700 μmol / g or less, 600 μmol / g or less, 500 μmol / g or less, 400 μmol / g or less, 300 μmol / g or less, 200 μmol / g or less, or 100 μmol / g or less.

[0087] The amount of acid sites in the catalyst can be measured by the ammonia temperature-controlled desorption method. For example, the ammonia temperature-controlled desorption method can be performed using the temperature-controlled desorption apparatus TPD-1-Atw (manufactured by Microtrac-Bell) by the following measurement method.

[0088] 50 mg of hydrogenation catalyst is weighed and helium is passed through it at 500°C at a rate of 50 mL / min for 60 minutes. Then, the temperature is lowered to 250°C, and 0.5% ammonia / helium is passed through it at 100 mL / min for 30 minutes to adsorb ammonia onto the surface of the hydrogenation catalyst. Furthermore, helium is passed through it at 100°C at a rate of 50 mL / min for 30 minutes. Then, while passing helium at 50 mL / min through the hydrogenation catalyst, the temperature is raised from 250°C to 650°C at a heating rate of 10°C / min, and the amount of ammonia desorbed is measured using a quadrupole mass spectrometer. Using the absolute calibration curve method, the amount of ammonia desorbed per unit mass is calculated from the area value of the TPD spectrum obtained from the measurement, and this is determined as the amount of acid sites per unit mass of catalyst.

[0089] The amount of acid sites in the catalyst containing the zeolite can be increased by lowering the silica / alumina ratio during zeolite synthesis, or decreased by increasing the silica / alumina ratio.

[0090] By having the amount of acid sites in the catalyst within the above numerical range, the yield of olefins in the olefin production method is improved.

[0091] 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.

[0092] 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".

[0093] 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.

[0094] In the crude olefin production step, a fluidized bed, a moving bed, or a fixed bed may be formed using a zeolite-containing catalyst.

[0095] In the crude olefin production step, the weight hourly space velocity (WHSV) required for catalytic cracking of the zeolite-containing catalyst is preferably 0.5 h －１ or more and 30 h －１ or less, more preferably 1 h －１ or more and 15 h －１ or less.

[0096] When the residence time required for catalytic cracking of the zeolite-containing catalyst in the crude olefin production step falls within the above numerical range, the proportion of unreacted hydrocarbon stream can be reduced in the crude olefin production step.

[0097] The crude olefin contains an olefin, and preferably contains an olefin and hydrogen.

[0098] Examples of the olefin contained in the crude olefin include olefins having 2 to 4 carbon atoms. Examples of the olefins having 2 to 4 carbon atoms include ethylene, propylene, 1-butene, 2-butene, and isobutene. The crude olefin according to the first embodiment preferably contains at least one of ethylene and propylene.

[0099] The content of the olefin in the crude olefin is preferably 50% by mass or more and 85% by mass or less, more preferably 55% by mass or more and 80% by mass or less. From the viewpoint of improving the yield of olefin in the method for producing an olefin, the content of the olefins having 2 to 4 carbon atoms in the crude olefin is preferably 45% by mass or more and 80% by mass or less, more preferably 50% by mass or more and 75% by mass or less.

[0100] In the crude olefin production step, the temperature for carrying out the catalytic cracking is preferably 400°C or higher and 800°C or lower, more preferably 450°C or higher and 650°C or lower, and still more preferably 500°C or higher and 600°C or lower.

[0101] 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.

[0102] (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 hydrogen 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.

[0103] In one embodiment of the method for producing an olefin according to the first embodiment, the separation step is a step of further separating hydrogen from the crude olefin, and the hydrogen is used for hydrogenation in the hydrogenation step.

[0104] The crude olefin and the olefin having 2 to 4 carbon atoms in the separation step are the same as those described in the section on the crude olefin production step.

[0105] 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.

[0106] The method for producing olefins according to the first embodiment includes a hydrogenation step of obtaining a hydrogenation product by hydrogenating a hydrocarbon stream containing olefins, obtained by thermally decomposing a waste plastic raw material containing polyolefins, while leaving at least a portion of the olefins intact, and a crude olefin production step of obtaining crude olefins from the hydrogenation product using a catalyst containing zeolite.

[0107] The above-mentioned method for producing olefins, with this configuration, can suppress a decrease in olefin yield by leaving a portion of the olefin contained in the hydrocarbon stream in the hydrogenation step. Furthermore, by hydrogenating the hydrocarbon stream in the hydrogenation step, substances that poison the catalyst contained in waste plastics can be decomposed and discharged, thereby reducing catalyst poisoning.

[0108] In the method for producing the olefin, the olefin content in the hydrogenation product in the hydrogenation step is 20% by mass or more.

[0109] The above-mentioned method for producing olefins, with this configuration, improves the yield of the final product, olefin, because the olefin content in the hydrogenation product in the hydrogenation step is 20% by mass or more.

[0110] The method for producing the olefin described above is such that the amount of acid sites measured at 250 to 650°C by the ammonia heating desorption method of the catalyst is greater than 0 μmol / g and less than or equal to 800 μmol / g.

[0111] The above-mentioned method for producing olefins, with this configuration, can reduce the proportion of unreacted hydrogenation products because the amount of acid sites in the catalyst is within the above-mentioned numerical range, thereby improving the yield of the final product, the olefin.

[0112] The method for producing the olefin further includes a separation step of separating an olefin having 2 to 4 carbon atoms from the crude olefin, wherein the separation step is a step of further separating hydrogen from the crude olefin, and the hydrogen is used for hydrogenation in the hydrogenation step.

[0113] The above-mentioned method for producing olefins, with this configuration, allows the hydrogen separated from the crude olefin in the separation step to be used for hydrogenation in the hydrogenation step, thereby supplementing the hydrogen source required in the hydrogenation step with by-products generated in the crude olefin production step, and thus contributing to a reduction in environmental impact.

[0114] The method for producing the olefin is a hydrogenation step in which the hydrocarbon stream is hydrogenated and then washed with water to obtain the hydrogenation product.

[0115] The above-mentioned method for producing olefins, with this configuration, allows for the removal of substances that can poison the catalyst, such as hydrochloric acid, amines, and hydrogen sulfide, from the hydrogenated hydrocarbon stream before the crude olefin production step by washing the hydrocarbon stream with water after hydrogenation. This reduces catalyst poisoning, maintains catalyst activity, and improves the yield of the final product, olefin.

[0116] The method for producing olefins according to the second embodiment includes a crude olefin production step in which crude olefins are obtained from hydrogenation products obtained by a hydrogenation product production method described later, using a catalyst containing zeolite.

[0117] A method for producing olefins according to the third embodiment includes: a thermal decomposition step of thermally decomposing a waste plastic raw material containing polyolefin to obtain a hydrocarbon stream containing olefin; a hydrogenation step of hydrogenating the hydrocarbon stream while leaving at least a portion of the olefin intact to obtain a hydrogenation product; a crude olefin production step of obtaining crude olefin from the hydrogenation product using a catalyst containing zeolite; and a separation step of separating olefins having 2 to 4 carbon atoms from the crude olefin.

[0118] The aforementioned thermal decomposition step is the same as the thermal decomposition step in the first embodiment of the method for producing olefins according to this embodiment, so its description will not be repeated.

[0119] Since the hydrogenation step is the same as the hydrogenation step in the first embodiment of the method for producing olefins according to this embodiment, its description will not be repeated.

[0120] The crude olefin production step is the same as the crude olefin production step in the first embodiment of the olefin production method according to this embodiment, so its description will not be repeated.

[0121] The separation step described above is the same as the separation step in the first embodiment of the method for producing olefins according to this embodiment, so its description will not be repeated.

[0122] The methods for producing olefins according to each embodiment of the present invention, when implemented in the manner described above, can reduce catalyst poisoning while suppressing a decrease in olefin yield in catalytic cracking using waste plastic raw materials.

[0123] [Method for Producing Hydrogenated Products] The following describes embodiments of the method for producing hydrogenated products according to the present invention, but the present invention is not limited to the following embodiments. Note that items described in the embodiments for producing olefins will not be repeated.

[0124] The method for producing the hydrogenation product according to this embodiment produces a hydrogenation product used in the crude olefin production step, which involves obtaining a crude olefin from the hydrogenation product using a catalyst containing zeolite.

[0125] The method for producing hydrocarbon oil according to this embodiment includes a hydrogenation step in which a hydrocarbon stream containing olefins, obtained by thermal decomposing a waste plastic raw material containing polyolefins, is hydrogenated while leaving at least a portion of the olefins intact, in order to obtain a hydrogenation product.

[0126] The olefin content in the hydrogenation product in the hydrogenation step is preferably 20% by mass or more, more preferably 25% by mass or more and 85% by mass or less, and even more preferably 30% by mass or more and 85% by mass or less. The method for measuring the olefin content in the hydrogenation product in the hydrogenation step is the same as described above.

[0127] The above-mentioned hydrocarbon oil production method, with this configuration, improves the yield of the final product, olefin, because the olefin content in the hydrogenation product in the hydrogenation step is 20% by mass or more.

[0128] The catalyst, crude olefin, crude olefin production process, polyolefin, waste plastic raw material, olefin, hydrocarbon flow, and hydrogenation product are the same as those described in the method for producing olefins.

[0129] The method for producing the hydrogenation product according to this embodiment, when implemented in the manner described above, can reduce catalyst poisoning while suppressing a decrease in olefin yield in catalytic cracking using waste plastic raw materials.

[0130] The present invention includes the following embodiments.

[0131] [1] A method for producing an olefin, comprising: a hydrogenation step of obtaining a hydrogenation product by hydrogenating a hydrocarbon stream containing an olefin, obtained by thermally decomposing a waste plastic raw material containing a polyolefin, while leaving at least a portion of the olefin; and a crude olefin production step of obtaining a crude olefin from the hydrogenation product using a catalyst containing a zeolite. [2] The method for producing an olefin according to [1], wherein the olefin content in the hydrogenation product in the hydrogenation step is 20% by mass or more. [3] A method for producing a hydrogenation product used in the crude olefin production step of obtaining a crude olefin from a hydrogenation product using a catalyst containing a zeolite, comprising a hydrogenation step of obtaining a hydrogenation product by hydrogenating a hydrocarbon stream containing an olefin, obtained by thermally decomposing a waste plastic raw material containing a polyolefin, while leaving at least a portion of the olefin; and the method for producing a hydrogenation product according to [3], wherein the olefin content in the hydrogenation product in the hydrogenation step is 20% by mass or more. [5] A method for producing an olefin, comprising a crude olefin production step of obtaining a crude olefin from a hydrogenation product obtained by the method for producing a hydrogenation product described in [3] or [4] using a catalyst containing zeolite. [6] A method for producing an olefin according to any one of [1], [2], or [5], wherein the amount of acid sites measured at 250 to 650°C by an ammonia heating desorption method of the catalyst is greater than 0 μmol / g and less than or equal to 800 μmol / g. [7] A method for producing an olefin according to any one of [1], [2], [5], or [6], further comprising a separation step of separating an olefin having 2 to 4 carbon atoms from the crude olefin, wherein the separation step is a step of further separating hydrogen from the crude olefin, and the hydrogen is used for hydrogenation in the hydrogenation step. [8] A method for producing an olefin according to any one of [1], [2], or [5] to [7], wherein the hydrogenation step is a step of hydrogenating the hydrocarbon stream and then further washing it with water to obtain the hydrogenation product.

[0132] It should be noted that the method for producing olefins and hydrogenation products 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 hydrogenation step of obtaining a hydrogenation product by hydrogenating a hydrocarbon stream containing olefins, obtained by thermally decomposing a waste plastic raw material containing polyolefins, while leaving at least a portion of the olefins intact; and a crude olefin production step of obtaining crude olefins from the hydrogenation product using a catalyst containing zeolite.

2. The method for producing an olefin according to claim 1, wherein the content of olefin in the hydrogenation product in the hydrogenation step is 20% by mass or more.

3. A method for producing a hydrogenation product used in a crude olefin production step to obtain a crude olefin from a hydrogenation product using a catalyst containing zeolite, comprising a hydrogenation step of hydrogenating a hydrocarbon stream containing olefin, obtained by thermally decomposing a waste plastic raw material containing polyolefin, while leaving at least a portion of the olefin, to obtain a hydrogenation product.

4. The method for producing a hydrogenation product according to claim 3, wherein the content of olefin in the hydrogenation product in the hydrogenation step is 20% by mass or more.

5. A method for producing an olefin, comprising a crude olefin production step of obtaining a crude olefin from a hydrogenation product obtained by the method for producing a hydrogenation product according to claim 3 or 4, using a catalyst containing zeolite.

6. The method for producing an olefin according to any one of claims 1, 2, or 5, wherein the amount of acid sites measured at 250 to 650°C by the ammonia heating desorption method of the catalyst is greater than 0 μmol / g and less than or equal to 800 μmol / g.

7. A method for producing an olefin according to any one of claims 1, 2, 5, or 6, further comprising a separation step of separating an olefin having 2 to 4 carbon atoms from the crude olefin, wherein the separation step is a step of further separating hydrogen from the crude olefin, and the hydrogen is used for hydrogenation in the hydrogenation step.

8. The method for producing an olefin according to any one of claims 1, 2, or 5 to 7, wherein the hydrogenation step is a step of hydrogenating the hydrocarbon stream and then washing it with water to obtain the hydrogenation product.