Olefin production process

Abstract

Provided is a method for producing an olefin, which can reduce the decrease in catalytic activity of a zeolite even when a polyolefin containing polyethylene terephthalate is used as the raw material. [Solution] The manufacturing method of the present disclosure has the following steps: Step S12: A step of obtaining hydrocarbons by thermally cracking a raw material containing polyolefin and polyethylene terephthalate. Step S13: A step of obtaining olefins by catalytically cracking the hydrocarbons using a catalyst containing zeolite. In Step S12, the content of polyethylene terephthalate in the raw material is 0.1 mass% or more, where the total content of polyolefin and polyethylene terephthalate is 100 mass%. In Step S13, the amount of acid sites of the catalyst containing zeolite is 30 to 800 μmol / g, as measured by ammonia temperature programmed desorption at 250 to 650°C.

Description

[Technical Field]

[0001] The present invention relates to a process for producing olefins. [Background technology]

[0002] Olefins, the main raw material for plastics, are usually produced from petroleum. However, in recent years, with the aim of realizing a carbon-recycling society, technologies for producing olefins from waste plastics have been developed. For example, Patent Document 1 discloses a method for producing olefins by thermal cracking and catalytic cracking of polyolefins, which are raw materials. In this document, the catalyst used for catalytic cracking is MFI-type zeolite. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2021 / 166854 Summary of the Invention [Problem to be solved by the invention]

[0004] Plastic products used daily generally contain polymers other than polyolefins. In this regard, the present inventors have found that when the technology described in Patent Document 1 is used in a case where the raw material is a mixture, the catalytic activity of the zeolite may decrease. Specifically, when the technology described in Patent Document 1 is used in a case where a raw material containing polyethylene terephthalate mixed with polyolefin is used, the catalytic activity may decrease depending on the number of acid sites of the zeolite.

[0005] An object of one aspect of the present invention is to provide a method for producing an olefin that can reduce the decrease in catalytic activity of a zeolite even when a polyolefin containing polyethylene terephthalate is used as a raw material. [Means for solving the problem]

[0006] The present invention includes the following aspects. <1> A method for producing an olefin, comprising the following steps S12 and S13: Step S12: pyrolyzing a raw material containing polyolefin and polyethylene terephthalate to obtain hydrocarbons; Step S13: catalytically cracking the hydrocarbons using a catalyst containing zeolite to obtain olefins; where: In the step S12, the content of the polyethylene terephthalate in the raw material is 0.1% by mass or more, where the total content of the polyolefin and the polyethylene terephthalate is 100% by mass; In the step S13, the amount of acid sites of the catalyst containing the zeolite measured by an ammonia temperature programmed desorption method at 250 to 650°C is 30 to 800 μmol / g. A method for producing olefins. <2> The hydrocarbons obtained in step S12 are gaseous and / or liquid. <1> The manufacturing method described in <3> The olefins obtained in step S13 include one or more olefins selected from the group consisting of ethylene, propylene, butene, and pentene. <1> or <2> The manufacturing method described in <4> In the step S13, the zeolite has an MFI structure. <1> ~ <3> 1. The manufacturing method according to any one of the preceding claims. <5> In the step S13, the zeolite contains phosphorus. <1> ~ <4> 1. The manufacturing method according to any one of the preceding claims. <6> The step S13 is carried out under conditions that satisfy the following (i) and (ii): <1> ~ <5> A manufacturing method according to any one of the following: (i) In the presence of a carrier gas supplied to the reaction system; (ii) The reaction temperature is 400 to 800°C. <7> The carrier gas is water vapor and / or nitrogen gas. <6> The manufacturing method described in <8> The flow rate of the carrier gas is 0.05 to 1.0 in parts by mass, assuming that the flow rate of the hydrocarbon supplied in step S13 is 1. <6> or <7> The manufacturing method described in [Effects of the Invention]

[0007] According to one aspect of the present invention, there is provided a method for producing an olefin, which can reduce the decrease in catalytic activity of a zeolite even when a polyolefin containing polyethylene terephthalate is used as a raw material. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a flow chart illustrating an example of a manufacturing method according to one embodiment of the present invention. [Figure 2] FIG. 1 is a block diagram illustrating an example implementation of a manufacturing method according to an aspect of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0009] An embodiment of the present invention will be described below. However, the present invention is not limited to the configurations described below. The present invention can be modified in various ways within the scope of the claims. The technical scope of the present invention also extends to embodiments or examples obtained by appropriately combining multiple technical means disclosed in this specification. In this case, multiple technical means may be disclosed across multiple embodiments or examples.

[0010] Unless otherwise specified in this specification, the expression "A to B" representing a numerical range means "greater than or equal to A and less than or equal to B."

[0011] 1. Olefin Production Method An olefin production method according to one embodiment of the present invention will be described below with reference to illustrative Figure 1. In the production method shown in Figure 1, steps S11, S12, S13, and S14 are carried out in this order. Among these, steps S11 and S14 are optional steps and may or may not be carried out.

[0012] According to this production method, polyolefin is decomposed to obtain an olefin-rich gas that is rich in olefins (particularly lower olefins having 2 to 5 carbon atoms). Each step will be described in detail below.

[0013] [1.1. Step S11: Pretreatment] In step S11, plastics are pretreated. The pretreated plastics become a feed M containing mainly polyolefins, which is sent to step S12. The plastics supplied to step S11 are, for example, waste plastics, and contain polyolefins (polyethylene, polypropylene, etc.). When comparing the plastics supplied to step S11 with the feed M sent to step S12, the latter usually has a higher polyolefin content.

[0014] The polyolefin content in the plastics supplied to step S11 may be 60% by mass or more, 80% by mass or more, or 90% by mass or more, based on 100% by mass of the total amount of plastics. The polyolefin content in feed M may be 80% by mass or more, 90% by mass or more, or 95% by mass or more, based on 100% by mass of the total amount of feed M.

[0015] Feed M contains polyethylene terephthalate in addition to polyolefin. The lower limit of the polyethylene terephthalate content in feed M is 0.1% by mass or more, and may be 0.5% by mass or more, or 1% by mass or more, based on 100% by mass of the total content of polyolefin and polyethylene terephthalate. The upper limit of the polyethylene terephthalate content in feed M may be 25% by mass or less, 20% by mass or less, or 15% by mass or less, based on 100% by mass of the total content of polyolefin and polyethylene terephthalate. Furthermore, the lower limit of the polyethylene terephthalate content in feed M may be 0.05% by mass or more, 0.1% by mass or more, 0.25% by mass or more, 0.5% by mass or more, 0.75% by mass or more, or 1% by mass or more, based on 100% by mass of the total amount of feed M. The upper limit of the polyethylene terephthalate content in feed M can be 25% by mass or less, 22.5% by mass or less, 20% by mass or less, 17.5% by mass or less, 15% by mass or less, 12.5% ​​by mass or less, or 10% by mass or less, where the total content of polyolefin and polyethylene terephthalate is 100% by mass.

[0016] [1.2.Step S12: Pyrolysis] In step S12, the feedstock M is thermally cracked. The first product P1 obtained by the thermal cracking mainly contains hydrocarbons and is sent to step S13. The carbon number of the hydrocarbons contained in the first product P1 may be 1 to 30. The average carbon number of the hydrocarbons contained in the first product P1 may be 8 to 30. The hydrocarbons contained in the first product P1 may be in the form of a gas, a liquid, or a mixture thereof. In one embodiment, the hydrocarbons contained in the first product P1 include one or more selected from the group consisting of normal paraffins, cycloparaffins, isoparaffins, olefins, cycloolefins, and isoolefins.

[0017] The pyrolysis temperature in step S12 may be set based on the composition of the feed material M. A high pyrolysis temperature increases the decomposition rate of the plastic, but if the temperature is too high, the plastic will be carbonized. Taking this into consideration, the upper limit of the pyrolysis temperature may be 800°C or lower, 595°C or lower, or 550°C or lower. The lower limit of the pyrolysis temperature may be 350°C or higher, 380°C or higher, or 400°C or higher.

[0018] At least a portion of the heat source required in step S12 may be supplied by combustion. Examples of fuels used in combustion include the pyrolysis residue in step S12, hydrocarbon-containing liquid and / or lower paraffin gas in step S14, and fuel introduced from outside the system (natural gas, kerosene, etc.). Alternatively, at least a portion of the heat source required in step S12 may be supplied by electrical heating or microwave irradiation.

[0019] The heating method may be a direct heating method or an indirect heating method. An example of a direct heating method is a method in which microwave energy is directly supplied to the feed material M via a microwave-absorbing material (susceptor). Examples of indirect heating methods include a method in which heat obtained from an electric heater or combustion is supplied via the heat transfer surface of the device, a method in which a high-temperature gas (water vapor, nitrogen gas, CO2 gas, etc.) is introduced into the device, and a method in which high-temperature solid particles (mainly composed of iron, iron oxide, alumina, silica, etc.) are introduced into the device. To preheat the gas or solid particles introduced into the device, a device similar to the device used in step S12 may be used, or a device combined with the device used in step S12 may be used. The gas or solid particles introduced into the device may be circulated.

[0020] The pressure in step S12 is preferably low because the number of moles increases due to the thermal decomposition reaction. The lower limit of the gauge pressure in step S12 may be -80 kPaG or more, -10 kPaG or more, or 0 kPaG or more. The upper limit of the gauge pressure may be 1000 kPaG or less, 300 kPaG or less, or 100 kPaG or less.

[0021] In step S12, a catalyst may be used to promote the thermal decomposition. Examples of catalysts that may be used include silicate catalysts. Silicate catalysts typically contain silicon, aluminum, oxygen, and hydrogen atoms. The silicate catalyst may also contain atoms such as sodium, titanium, chromium, manganese, iron, cobalt, nickel, copper, ruthenium, rhodium, palladium, silver, iridium, platinum, boron, nitrogen, magnesium, phosphorus, zinc, and gallium. In one embodiment, the silicate catalyst is a zeolite. In one embodiment, the zeolite is an MFI-type zeolite. The zeolite may be one described in step S13.

[0022] Step S12 may be performed in the presence or absence of a carrier gas. The carrier gas refers to a gas introduced into the reaction system to fluidize the decomposition products. The carrier gas may be introduced in step S12, or may be introduced in a step prior to step S12. On the other hand, gases generated in steps S12 and S13 are not included in the carrier gas. Examples of carrier gases include inert gases (nitrogen gas, argon gas, etc.), water vapor, and CO2 gas. In one embodiment, the carrier gas is nitrogen gas and / or water vapor.

[0023] The flow rate of the carrier gas can be adjusted as appropriate so that the hydrocarbon concentration in the first product P1 sent to step S13 is within an appropriate range. The lower limit of the mass of the carrier gas sent to step S13 may be 0.05 or more, 0.1 or more, or 0.15 or more, where the mass of the hydrocarbons sent to step S13 is 1. The lower limit of the mass of the carrier gas sent to step S13 may be 1 or less, 0.75 or less, or 0.5 or less, where the mass of the hydrocarbons sent to step S13 is 1.

[0024] In an embodiment in which step S12 is performed using a fluidized bed reactor, the more fluidizing gas there is, the lower the hydrocarbon concentration in the gas phase becomes, and therefore the more easily the cracked components are vaporized. Based on this, the lower limit of the linear velocity of the fluidizing gas in the fluidized bed reactor can be 0.1 cm / s or more, 0.5 cm / s or more, or 0.8 cm / s or more. The upper limit of the linear velocity of the fluidizing gas in the fluidized bed reactor can be 100 cm / s or less, 75 cm / s or less, or 20 cm / s or less.

[0025] In this embodiment, the lower limit of the ratio of the fluidizing gas feed rate (NmL / min) to the feed rate (g / min) of the feed material M fed to the fluidized bed reactor may be 10 NmL / g or more, 50 NmL / g or more, or 200 NmL / g or more. The upper limit of the ratio of the fluidizing gas feed rate (NmL / min) to the feed rate (g / min) of the feed material M fed to the fluidized bed reactor may be 2000 NmL / g or less, 1500 NmL / g or less, or 1200 NmL / g or less.

[0026] In this embodiment, the lower limit of the ratio of the fluidizing gas supply rate (NmL / min) to the amount of bed material (g) present in the fluidized-bed reactor may be 1.0 NmL / g·min or more, 2.0 NmL / g·min or more, or 3.0 NmL / g·min or more. The upper limit of the ratio of the fluidizing gas supply rate (NmL / min) to the amount of bed material (g) present in the fluidized-bed reactor may be 100 NmL / g·min or less, 50 NmL / g·min or less, or 25 NmL / g·min or less.

[0027] [1.3.Step S13: Catalytic cracking] In step S13, the first product P1 is catalytically cracked in the presence of a catalyst containing zeolite. The second product P2 obtained by catalytic cracking mainly contains olefins and is sent to step S14. The carbon number of the olefins contained in the second product P2 may be 2 to 5.

[0028] In one embodiment, the second product P2 contains one or more hydrocarbons selected from the group consisting of ethylene, propylene, butene, and pentene. The proportion of ethylene, propylene, butene, and pentene in the hydrocarbons contained in the second product P2 may be 32% by mass or more, 35% by mass or more, or 40% by mass or more.

[0029] The catalytic cracking temperature in step S13 may be set based on the composition of the first product P1. The lower limit of the catalytic cracking temperature may be 400°C or higher, 450°C or higher, or 500°C or higher. The upper limit of the catalytic cracking temperature may be 800°C or lower, 650°C or lower, or 600°C or lower. The heat source required for step S13 may be supplied in the same manner as in step S12.

[0030] The lower limit of the gauge pressure in step S13 may be −80 kPaG or more, −10 kPaG or more, or 0 kPaG or more. The upper limit of the gauge pressure may be 1000 kPaG or less, 300 kPaG or less, or 100 kPaG or less.

[0031] Step S13 may be performed in the presence or absence of a carrier gas. The definition and examples of the carrier gas are as described in relation to step S12. The carrier gas may be introduced in step S13, or may be introduced in a step prior to step S13. In one embodiment, the carrier gas is nitrogen gas and / or water vapor.

[0032] The flow rate of the carrier gas can be adjusted as appropriate so that the olefin concentration in the second product P2 sent to step S14 is within an appropriate range. The lower limit of the mass of the carrier gas sent to step S14 may be 0.05 or more, 0.1 or more, or 0.15 or more, where the mass of the olefin sent to step S14 is 1. The lower limit of the mass of the carrier gas sent to step S14 may be 1 or less, 0.75 or less, or 0.5 or less, where the mass of the olefin sent to step S14 is 1.

[0033] The lower limit of the contact time in step S13 may be 200 seconds or more, 300 seconds or more, or 400 seconds or more. The upper limit of the contact time in step S13 may be 1000 seconds or less, 900 seconds or less, or 800 seconds or less. The contact time in step S13 is a value calculated by dividing the mass-based flow rate (g / sec) of the hydrocarbons supplied to step S13 by the mass (g) of the zeolite-containing catalyst.

[0034] 1.3.1. Zeolite-containing catalysts In step S13, hydrocarbons are catalytically cracked using a catalyst containing zeolite. Zeolite typically contains silicon, aluminum, oxygen, and hydrogen atoms. In addition to the above atoms, zeolite may also contain atoms such as titanium, chromium, manganese, iron, cobalt, nickel, copper, ruthenium, rhodium, palladium, silver, iridium, platinum, boron, nitrogen, magnesium, phosphorus, zinc, sodium, and gallium.

[0035] Examples of zeolites include beta zeolite, faujasite zeolite, L zeolite, ferrierite zeolite, mordenite zeolite, and MFI zeolite.

[0036] In one embodiment, the zeolite comprises or consists of an MFI zeolite. MFI zeolite refers to a crystalline aluminosilicate having an MFI structure according to the structure code of the International Zeolite Association (IZA), and is also called ZSM-5. Specific examples of MFI zeolite include H + -ZSM-5, NH4 + -ZSM-5, Na + -ZSM-5, Ca 2+ -ZSM-5 is an example.

[0037] The lower limit of the amount of acid sites of the zeolite-containing catalyst used in step S13 is 30 μmol / g or more, and may be 40 μmol / g or more, or 50 μmol / g or more. The upper limit of the amount of acid sites of the zeolite-containing catalyst used in step S13 is 800 μmol / g or less, and may be 700 μmol / g or less, 600 μmol / g or less, 500 μmol / g or less, 400 μmol / g or less, or 300 μmol / g or less.

[0038] In this specification, the amount of acid sites in the catalyst is measured by an ammonia adsorption / desorption method. An example of a measuring device is a temperature-programmed desorption device TPD-1-Atw (Microtrack Bell Corporation). The specific measuring method is as follows (this method was also adopted in the examples of the present application described later). 1. Weigh out 50 mg of catalyst and pass helium through it at 500°C for 60 minutes at a flow rate of 50 mL / min. 2. The catalyst is cooled to 100°C. 0.5% ammonia / helium is passed through the catalyst at 100°C for 30 minutes at a flow rate of 100 mL / min. This allows ammonia to be adsorbed onto the catalyst surface. 3. Helium is passed through the tube at 100°C for 30 minutes at a flow rate of 50 mL / min. 4. The temperature is increased from 100°C to 800°C at a rate of 10°C / min, and the amount of ammonia desorbed between 250°C and 650°C is measured using a quadrupole mass spectrometer. 5. From the obtained TPD spectrum, calculate the area value using the absolute calibration curve method. From the obtained area, calculate the amount of ammonia desorbed per unit mass. This amount of ammonia desorbed is the amount of acid sites per unit mass of the catalyst.

[0039] The catalyst used in step S13 may contain components other than zeolite. Examples of such components include a carrier and a binder (matrix material). Examples of carriers include silica, alumina, silica-alumina, silica-titania, silica-thoria, silica-magnesia, silica-zironia, silica-beryllia, and ternary compositions of silica and other refractory oxides. Examples of binders (matrix materials) include clays (montmorillonite, kaolin, bentonite, halloysite, dickite, nacrite, anaxite, etc.). The mass proportion of zeolite in the catalyst used in step S13 may be 50 mass% or more, 70 mass% or more, or 90 mass% or more. In one embodiment, the catalyst used in step S13 consists solely of zeolite.

[0040] (Zeolite manufacturing method) The zeolite used in step S13 can be produced by a conventional method. An example of a method for producing MFI zeolite is shown below. MFI zeolite can be produced by crystallizing a mixture containing a silicon source, an aluminum source, a template, and an alkali metal source. Here, the template is a substance that forms a pore structure in the crystalline aluminosilicate.

[0041] The silicon source may be any conventional silica-containing material known to those skilled in the art for use in the manufacture of zeolites, including tetraethyl orthosilicate, colloidal silica, silica gel dry powder, and silica hydrogel.

[0042] The aluminum source may be any known aluminum source used in the production of zeolites. Specific examples of the aluminum source include aluminum nitrate, aluminum chloride, and sodium aluminate. Among these aluminum sources, aluminum nitrate and sodium aluminate are preferred.

[0043] The template may be a known template used in the synthesis of MFI zeolite. Specific examples of the template include tetrapropylammonium salt, tetraethylammonium salt, propanolamine, ethanolamine, n-propylamine, morpholine, 1,5-diaminopentane, 1,6-diaminohexane, dipropylenetetramine, and triethylenetetramine. Among these templates, tetrapropylammonium salt is preferred.

[0044] Examples of the alkali metal source include hydroxides containing alkali metals, chlorides containing alkali metals, bromides containing alkali metals, and sulfides containing alkali metals. Examples of alkali metals include sodium and potassium.

[0045] When the alkali metal is sodium, the sodium source is a compound containing sodium. Examples of the sodium-containing compound include compounds containing sodium as a counter cation. More specifically, sodium hydroxide, sodium chloride, sodium bromide, sodium sulfate, sodium silicate, and sodium aluminate are included.

[0046] When the alkali metal is potassium, the potassium source is a compound containing potassium. Examples of the potassium-containing compound include compounds containing potassium as a counter cation. More specifically, potassium hydroxide, potassium chloride, potassium bromide, potassium sulfate, potassium silicate, and potassium aluminate are included.

[0047] The ratio of the number of moles of silicon atoms to the number of moles of aluminum atoms in the mixture before crystallization can be 10-1,000.

[0048] The molar numbers of the template, alkali source, and water contained in the mixture before crystallization are preferably in the following ranges, assuming that the molar number of silicon atoms is 1: Mold: 0.02~5.0 Alkaline source: 0.01~0.2 ·Wed: 2~100

[0049] MFI zeolite can be prepared by crystallizing the above mixture in a sealed pressure vessel. The reaction temperature is, for example, 100°C to 200°C. The reaction time is, for example, 1 to 120 hours. The MFI zeolite obtained by crystallization is usually washed and then dried. The drying temperature is, for example, 100°C to 150°C. The dried MFI zeolite may further be calcined. The calcination temperature is, for example, 300°C to 700°C.

[0050] For example, by incorporating phosphorus, the number of acid sites in MFI zeolite can be changed. Generally, the higher the phosphorus content, the lower the number of acid sites tends to be. To incorporate phosphorus into MFI zeolite, a phosphorus source may be added to the mixture before crystallization, or the crystallized MFI zeolite may be calcined together with the phosphorus source. Examples of phosphorus sources include phosphates.

[0051] The content of the alkali source (sodium and / or potassium) in the crystallized MFI zeolite may be reduced. For example, the content of the alkali source can be reduced by contacting the MFI zeolite with an aqueous solution of an ammonium salt. The amount of acid sites in the MFI zeolite can be changed by adjusting the amount of the alkali source. Generally, the lower the content of the alkali source, the greater the amount of acid sites.

[0052] Examples of ammonium salts include ammonium salts of inorganic acids (ammonium sulfate, ammonium hydrogen sulfate, ammonium carbonate, ammonium hydrogen carbonate, diammonium hydrogen phosphate, ammonium dihydrogen phosphate, ammonium phosphate, ammonium hydrogen pyrophosphate, ammonium pyrophosphate, ammonium chloride, ammonium nitrate, etc.) and ammonium salts of organic acids (ammonium acetate, etc.). Among these, ammonium sulfate, ammonium chloride, and ammonium nitrate are preferred.

[0053] Specifically, the alkali source can be reduced by mixing an aqueous solution of an ammonium salt with MFI zeolite. The mixing temperature is, for example, 50°C to 200°C. The mixing time is, for example, 1 to 48 hours. The MFI zeolite from which the alkali source has been reduced is usually washed and then dried. The drying temperature is, for example, 60°C to 150°C. The dried MFI zeolite may further be calcined. The calcination temperature is, for example, 300°C to 700°C.

[0054] [1.4.Step S14: Purification] In step S14, the second product P2 is purified. In one embodiment, in step S14, the second product P2 is separated into olefins and other hydrocarbons (such as paraffins). In one embodiment, in step S14, olefins with a small number of carbon atoms (such as olefins with 2 to 5 carbon atoms) are separated from other hydrocarbons (such as paraffins and olefins with 6 or more carbon atoms). In step S14, an olefin-rich gas containing a large amount of olefins is separated. The olefin content in the olefin-rich gas may be 90 mass% or more. The olefin-rich gas may contain one or more olefins selected from the group consisting of ethylene, propylene, butene, and pentene.

[0055] At least a portion of the components other than the olefin-rich gas separated in step S14 may be refluxed to step S12 or step S13, which can further improve the olefin yield.

[0056] Alternatively, at least a portion of the components other than the olefin-rich gas separated in step S14 may be combusted and used as a heat source in step S12 or step S13. This configuration reduces the environmental impact of the olefin production process.

[0057] [2. Olefin production system] The above-described olefin production method can be implemented by an olefin production system exemplified in Fig. 2. The production system 100 shown in Fig. 2 includes a pretreatment section 10, a thermal cracking section 21, a catalytic cracking section 22, and a purification section 30. These components are connected by paths L1 to L4.

[0058] Plastics such as waste plastics are supplied to the pretreatment unit 10 via a path L1. The outlet of the pretreatment unit 10 is connected to the thermal cracking unit 21 via a path L2. The plastics supplied to the pretreatment unit 10 are pretreated to produce a feed material M, which is then supplied to the thermal cracking unit 21 via the path L2. The outlet of the thermal cracking unit 21 is connected to the supply port of the catalytic cracking unit 22 via a path L3. The feed material M supplied to the thermal cracking unit 21 is thermally cracked to produce a first product P1, which is then supplied to the catalytic cracking unit 22 via the path L3. The catalytic cracking unit 22 and the purification unit 30 are connected via a path L4. The first product P1 supplied to the catalytic cracking unit 22 is catalytically cracked to produce a second product P2, which is then supplied to the purification unit 30 via the path L4. The second product P2 supplied to the purification unit 30 is refined to produce olefins, which are then extracted from the production system 100. Each unit is described in detail below.

[0059] The pretreatment unit 10 is a component that pretreats plastics, such as waste plastics, to provide a feedstock M suitable for decomposition. In other words, step S11 is performed in the pretreatment unit 10. The pretreatment unit 10 may include multiple devices that perform different processes. For example, the pretreatment unit 10 may include one or more devices selected from the group consisting of a sorting device, a crushing device, a washing device, a drying device, a melting device, and a dechlorination device. The sorting device is a device that separates polyolefins from plastics, such as waste plastics. Examples of sorting devices include an optical sorting device and a gravity separation device. The crushing device is a device that crushes plastics. The washing device is a device that washes plastics. The drying device is a device that dries plastics. The melting device is a device that heats plastics to liquefy them. The dechlorination device is a device that removes chlorine from plastics.

[0060] The thermal decomposition section 21 is a component that decomposes the feed material M by heating. That is, step S12 is carried out in the thermal decomposition section 21. The decomposed feed material M becomes a first product P1 containing gaseous and / or liquid hydrocarbons. The thermal decomposition section 21 may be an apparatus that continuously performs thermal decomposition. Specific examples thereof include an extruder, a stirring tank, a rotary kiln, and a fluidized bed. Examples of fluidized beds include an internal circulating fluidized bed and an external circulating fluidized bed. A plurality of the above-mentioned apparatuses may be used as the thermal decomposition section 21. The plurality of apparatuses may be connected in parallel or in series.

[0061] The catalytic cracking section 22 is a component that cracks the first product P1 by bringing it into contact with a catalyst. That is, in the catalytic cracking section 22, step S13 is carried out. The cracked first product P1 becomes a second product P2 containing olefins. Examples of the catalytic cracking section 22 include reactors including a fixed bed, a moving bed, or a fluidized bed. A plurality of the above-mentioned reactors may be used as the catalytic cracking section 22. The plurality of reactors may be connected in parallel or in series.

[0062] The purification section 30 is a component that separates and purifies the second product P2 to obtain olefins. That is, step S14 is carried out in the purification section 30. Examples of the purification section 30 include a gas-liquid separator and a distillation apparatus. A plurality of the above-mentioned devices may be used as the purification section 30. The plurality of devices may be connected in parallel or in series. [Example]

[0063] Example 1 An olefin was produced from a mixture of polyolefin and polyethylene terephthalate by a production method according to one embodiment of the present invention.

[0064] [Example 1-1] (Catalyst Preparation) 1 g of ammonium-type ZSM-5 (CBV28014, Zeolyst) was calcined in a muffle furnace to obtain catalyst A. The calcination conditions were an air atmosphere, 550°C, and 5 hours. The amount of acid sites (solid acidity) of catalyst A measured by ammonia temperature-programmed desorption at 250 to 650°C was 66 μmol / g.

[0065] (Olefin production) Olefins were produced using catalyst A according to the following procedure. 1. Two glass reaction tubes connected in series were prepared. The upstream reaction tube was filled with 0.95 g of polyethylene (Sumikathene G201F, Sumitomo Chemical Co., Ltd.) and 0.05 g of polyethylene terephthalate (Teijin Limited) as raw materials (polyethylene terephthalate content: 5% by mass). The downstream reaction tube was filled with 0.05 g of catalyst A. 2. A cold trap was connected further downstream of the downstream reaction tube. A 5 L gas bag was connected further downstream of the cold trap. 3. While flowing nitrogen gas from the upstream of the reaction tube (flow rate: 10 mL / min), only the downstream reaction tube was heated at 550°C for 1 hour to pretreat the catalyst. Then, the temperature of the downstream reaction tube was lowered to 525°C. 4. While flowing nitrogen gas (flow rate: 10 mL / min), the upstream reaction tube was heated to 455°C to pyrolyze the sample into hydrocarbons. The resulting hydrocarbons were supplied to the downstream reaction tube and brought into contact with a catalyst at 525°C for catalytic cracking. 5. Of the catalytic cracking products obtained 103 minutes after the start of heating the raw material, the liquid was collected in a cold trap and the gaseous product was collected in a gas bag.

[0066] The liquid and gaseous catalytic cracking products were analyzed by gas chromatography, and the yield of olefins having 2 to 5 carbon atoms was found to be 50.6% based on the mass of polyethylene charged as the raw material.

[0067] [Example 1-2] (Catalyst Preparation) Catalyst B was prepared according to the following procedure. 1. 16.4 g of an aqueous solution of tetrapropylammonium hydroxide (22.3 mass%), 15.0 g of tetraethyl orthosilicate, and 4.1 g of ion-exchanged water were placed in a 200 mL PTFE cylindrical container. The cylindrical container was then placed in a SUS autoclave. 2. The contents of the container were homogenized at room temperature, and then heated at 80°C for 24 hours with stirring. 3. After cooling the container, the entire contents were transferred to a glass flask, and the contents of the flask were evaporated in an evaporator at 80°C for 2 hours. 4. The entire amount of the mixture remaining in the flask was transferred to a PTFE container, and 0.18 g of aluminum nitrate nonahydrate, 0.29 g of sodium hydroxide, and 0.60 g of ion-exchanged water were added. Next, the contents of the container were stirred uniformly at room temperature using a stirrer. 5. The entire mixture was transferred to a 200 mL PTFE inner cylindrical container, which was then placed in a SUS autoclave. 6. The contents of the cylindrical container were heated at 170°C for 24 hours, then cooled in ice water. 7. The resulting suspension was centrifuged and the supernatant was removed. The precipitated residue was resuspended in water, centrifuged, and the supernatant was removed again. This procedure was repeated until the pH of the supernatant was 8 or less. 8. The precipitated residue was dried at 120°C for 8 hours. 9. The obtained solid was pulverized in a mortar. The pulverized material was then fired in a muffle furnace. The firing conditions were an air atmosphere, 550°C, and 6 hours. In this way, 2.9 g of a fired body was obtained. 10. 2.0 g of the calcined body and 100 mL of 0.5 M ammonium nitrate solution were placed in a resin container and allowed to stand at 60°C for 6 hours. The resulting mixture was then suction filtered using a Buchner funnel to recover the solids. This treatment with ammonium nitrate was repeated a total of three times. 11. The recovered solid was washed with 150 g of water and then dried at 90°C for 12 hours. 12. The obtained solid was calcined in a muffle furnace. The calcination conditions were an air atmosphere, 550°C, and 5 hours. In this way, 1.3 g of catalyst B was obtained. The amount of acid sites (solid acid amount) of catalyst B measured by ammonia temperature programmed desorption at 250 to 650°C was 89 μmol / g.

[0068] (Olefin production) The olefin production method of Example 1-1 was changed as follows: Except for the above, olefins were produced in the same manner as in Example 1-1. In step 1, the catalyst packed in the downstream reaction tube was changed from catalyst A to catalyst B. In step 5, the recovery time of catalytic cracking products was changed from 103 minutes to 102 minutes from the start of heating of the raw material.

[0069] The liquid and gaseous catalytic cracking products were analyzed by gas chromatography, and the yield of olefins having 2 to 5 carbon atoms was found to be 53.5% based on the mass of polyethylene charged as the raw material.

[0070] [Examples 1-3] (Catalyst Preparation) 1 g of ammonium-type ZSM-5 (CBV8014, Zeolyst) was calcined in a muffle furnace to obtain catalyst C. The calcination conditions were an air atmosphere, 550°C, and 5 hours. The amount of acid sites (solid acidity) of catalyst C measured by ammonia temperature-programmed desorption spectroscopy at 250 to 650°C was 279 μmol / g.

[0071] (Olefin production) In step 1 of the olefin production method of Example 1-1, the catalyst packed in the downstream reaction tube was changed from catalyst A to catalyst C. Except for this, olefins were produced in the same manner as in Example 1-1.

[0072] The liquid and gaseous catalytic cracking products were analyzed by gas chromatography, and the yield of olefins having 2 to 5 carbon atoms was found to be 51.0% based on the mass of polyethylene charged as the raw material.

[0073] [Examples 1-4] (Catalyst Preparation) Catalyst D was prepared according to the following procedure. 1. 12.0 g of ion-exchanged water and 0.03 g of diammonium hydrogen phosphate were added to a glass recovery flask and stirred at room temperature for 5 minutes. Next, 5.0 g of ammonium-type ZSM-5 (CBV28014, Zeolyst) was added to the flask. 2. The ion-exchanged water in the flask was evaporated using an evaporator at 60°C for 2 hours. 3. The entire residue was transferred to a porcelain dish and dried at 110°C for 12 hours. 4. The obtained solid was calcined in a muffle furnace. The calcination conditions were an air atmosphere, 600°C, and 4 hours. In this way, 4.9 g of catalyst D was obtained. The amount of acid sites (solid acid amount) of catalyst D measured by ammonia temperature programmed desorption at 250 to 650°C was 57 μmol / g.

[0074] (Olefin production) In step 1 of the olefin production method of Example 1-1, the catalyst packed in the downstream reaction tube was changed from catalyst A to catalyst D. Except for this, olefins were produced in the same manner as in Example 1-1.

[0075] The liquid and gaseous catalytic cracking products were analyzed by gas chromatography, and the yield of olefins having 2 to 5 carbon atoms was found to be 55.7% based on the mass of polyethylene charged as the raw material.

[0076] [Examples 1-5] (Catalyst Preparation) The same catalyst A as in Example 1-1 was prepared.

[0077] (Olefin production) In step 1 of the olefin production method of Example 1-1, the composition of the raw material charged into the upstream reaction tube was changed to 0.90 g of polyethylene (Sumikathene G201F, Sumitomo Chemical Co., Ltd.) and 0.10 g of polyethylene terephthalate (Teijin Limited) (polyethylene terephthalate content: 10 mass%). Otherwise, olefins were produced in the same manner as in Example 1-1.

[0078] The liquid and gaseous catalytic cracking products were analyzed by gas chromatography, and the yield of olefins having 2 to 5 carbon atoms was found to be 37.9% based on the mass of polyethylene charged as the raw material.

[0079] [Examples 1-6] (Catalyst Preparation) The same catalyst A as in Example 1-1 was prepared.

[0080] (Olefin production) In step 1 of the olefin production method of Example 1-1, the composition of the raw material filled in the upstream reaction tube was changed to 0.85 g of polyethylene (Sumikathene G201F, Sumitomo Chemical Co., Ltd.) and 0.15 g of polyethylene terephthalate (Teijin Limited) (polyethylene terephthalate content: 15 mass%). Otherwise, olefins were produced in the same manner as in Example 1-1.

[0081] The liquid and gaseous catalytic cracking products were analyzed by gas chromatography, and the yield of olefins having 2 to 5 carbon atoms was found to be 33.6% based on the mass of polyethylene charged as the raw material.

[0082] [Examples 1-7] (Catalyst Preparation) The same catalyst B as in Example 1-2 was prepared.

[0083] (Olefin production) The olefin production method of Example 1-1 was changed as follows: Except for the above, olefins were produced in the same manner as in Example 1-1. In step 1, the catalyst packed in the downstream reaction tube was changed from catalyst A to catalyst B. In step 1, the composition of the raw material filled in the upstream reaction tube was changed to 0.90 g of polyethylene (Sumikathene G201F, Sumitomo Chemical Co., Ltd.) and 0.10 g of polyethylene terephthalate (Teijin Limited) (polyethylene terephthalate content: 10% by mass). In step 5, the recovery time of catalytic cracking products was changed from 103 minutes to 102 minutes from the start of heating of the raw material.

[0084] The liquid and gaseous catalytic cracking products were analyzed by gas chromatography, and the yield of olefins having 2 to 5 carbon atoms was found to be 39.6% based on the mass of polyethylene charged as the raw material.

[0085] [Examples 1-8] (Catalyst Preparation) The same catalyst B as in Example 1-2 was prepared.

[0086] (Olefin production) The olefin production method of Example 1-1 was changed as follows: Except for the above, olefins were produced in the same manner as in Example 1-1. In step 1, the catalyst packed in the downstream reaction tube was changed from catalyst A to catalyst B. In step 1, the composition of the raw material charged into the upstream reaction tube was changed to 0.85 g of polyethylene (Sumikathene G201F, Sumitomo Chemical Co., Ltd.) and 0.15 g of polyethylene terephthalate (Teijin Limited) (polyethylene terephthalate content: 15% by mass). In step 5, the recovery time of catalytic cracking products was changed from 103 minutes to 102 minutes from the start of heating of the raw material.

[0087] The liquid and gaseous catalytic cracking products were analyzed by gas chromatography, and the yield of olefins having 2 to 5 carbon atoms was found to be 33.3% based on the mass of polyethylene charged as the raw material.

[0088] [result] The results of Example 1 are shown in Table 1. Please note that for ease of comparison, the order of entries in Table 1 is different from that of the above examples. [Table 1]

[0089] In Examples 1-1 to 1-3 and Comparative Examples 1-1 and 1-2, experiments were conducted by changing the number of acid sites on the catalyst. As can be seen from these results, the yield of olefins having 2 to 5 carbon atoms is affected by the number of acid sites on the catalyst. Specifically, to increase the yield, for example, the number of acid sites on the catalyst may be adjusted to a range of 30 to 800 μmol / g.

[0090] In Examples 1-4, the amount of acid sites was adjusted by adding phosphorus to the zeolite. Even when the zeolite with the amount of acid sites adjusted in this way was used as a catalyst, olefins were successfully produced by the production method according to one embodiment of the present invention.

[0091] In Examples 1-5 to 1-8, the content of polyethylene terephthalate in the raw material was increased. As the content increased, the yield of olefins having 2 to 5 carbon atoms tended to decrease, but a sufficient yield was still maintained according to the production method according to one embodiment of the present invention.

[0092] Example 9 By a production method according to one embodiment of the present invention, olefin was produced from a mixture containing polyolefin, polyethylene terephthalate, and other plastics.

[0093] (Catalyst Preparation) The same catalyst A as in Example 1-1 was prepared.

[0094] (Olefin production) Olefins were produced using catalyst A according to the following procedure. 1. Two metal reactors connected in series were prepared. The downstream reactor was filled with 2 g of catalyst A. A cold trap was connected downstream of the downstream reactor. A gas bag was connected downstream of the cold trap. 2. Mixed plastics (flow rate: 0.4 g / min) and nitrogen gas (flow rate: 0.06 g / min) were supplied to an upstream reactor heated to 550°C and pyrolyzed. The mixed plastics had the following composition: The proportion of polyethylene terephthalate in the polyolefin and polyethylene terephthalate was 3.3 mass%. 45 parts by weight of polyethylene (Sumikasen G201F, Sumitomo Chemical Co., Ltd.) 44 parts by weight of polypropylene (Noblen FS2011DG3, Sumitomo Chemical Co., Ltd.) 3 parts by weight of polyethylene terephthalate (Teijin Limited) 4 parts by weight polystyrene (Goodfellow Inc.) 0.5 parts by weight of polyvinyl chloride (Shin-Etsu Chemical Co., Ltd.) 0.5 parts by weight of polyvinylidene chloride (Goodfellow Inc.) 3 parts by weight of nylon 6 (UBE Corporation) 3. The entire amount of the reaction product from the upstream reactor and steam (flow rate: 0.1 g / min) were supplied to the downstream reactor heated to 525°C. This caused catalytic cracking of the hydrocarbons produced by thermal cracking. 4. Of the catalytic cracking products obtained between 1 hour 15 minutes and 1 hour 30 minutes after the start of mixed plastics supply, the liquid was collected in a cold trap. Also, of the catalytic cracking products obtained between 1 hour 20 minutes and 1 hour 30 minutes after the start of mixed plastics supply, the gaseous product was collected in a gas bag.

[0095] The liquid and gaseous catalytic cracking products were analyzed by gas chromatography, and the yield of olefins having 2 to 5 carbon atoms was found to be 51.9% based on the mass of the mixed plastics supplied as the raw material.

[0096] Thus, according to the production method according to one embodiment of the present invention, olefins could be successfully produced from raw materials containing plastics other than polyolefins and polyethylene terephthalate. [Industrial Applicability]

[0097] The present invention can be used to produce olefins.

Claims

1. A method for producing an olefin, comprising the following steps S12 and S13: Step S12: pyrolyzing a raw material containing polyolefin and polyethylene terephthalate to obtain hydrocarbons; Step S13: catalytically cracking the hydrocarbons using a catalyst containing zeolite to obtain olefins; where: In the step S12, the content of the polyethylene terephthalate in the raw material is 0.1% by mass or more, where the total content of the polyolefin and the polyethylene terephthalate is 100% by mass, In the step S13, the amount of acid sites of the catalyst containing the zeolite is 30 to 800 μmol / g as measured by an ammonia temperature programmed desorption method at 250 to 650°C, The steps S12 and S13 are carried out in different reaction vessels. A method for producing olefins.

2. A method for producing an olefin, comprising the following steps S12 and S13: Step S12: pyrolyzing a raw material containing polyolefin and polyethylene terephthalate to obtain hydrocarbons; Step S13: catalytically cracking the hydrocarbons using a catalyst containing zeolite to obtain olefins; where: In the step S12, the content of the polyethylene terephthalate in the raw material is 0.1% by mass or more, where the total content of the polyolefin and the polyethylene terephthalate is 100% by mass, In the step S13, the amount of acid sites of the catalyst containing the zeolite is 30 to 800 μmol / g as measured by an ammonia temperature programmed desorption method at 250 to 650°C, In the step S13, the zeolite contains phosphorus. A method for producing olefins.

3. The hydrocarbons obtained in step S12 are gaseous and / or liquid. The method according to claim 1 or 2.

4. The olefins obtained in step S13 include one or more olefins selected from the group consisting of ethylene, propylene, butene, and pentene. The method according to claim 1 or 2.

5. In the step S13, the zeolite has an MFI structure. The method according to claim 1 or 2.

6. In the step S13, the zeolite contains phosphorus. The method of claim 1.

7. The method according to claim 1 or 2, wherein step S13 is carried out under conditions that satisfy the following (i) and (ii): (i) In the presence of a carrier gas supplied to the reaction system; (ii) The reaction temperature is 400 to 800°C.

8. The carrier gas is water vapor and / or nitrogen gas. The method of claim 7.

9. The flow rate of the carrier gas is 0.05 to 1.0 parts by mass, assuming that the flow rate of the hydrocarbon supplied in step S13 is 1. The method of claim 7.

10. The thermal decomposition temperature in step S12 is 550°C or less. The method according to claim 1 or 2.

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