Method for producing olefins

Abstract

The present invention provides a method for producing olefins that can reduce the decrease in catalytic activity of zeolite even when using polyolefins containing polyethylene terephthalate as a raw material. [Solution] The manufacturing method of the present disclosure comprises the following steps: Step S12: A step of obtaining hydrocarbons by thermal decomposition of raw materials containing polyolefin and polyethylene terephthalate. Step S13: A step of obtaining olefins by catalytic decomposition of the hydrocarbons using a catalyst containing zeolite. In step S12, the content of polyethylene terephthalate in the raw materials is 0.1% by mass or more, with the total content of polyolefin and polyethylene terephthalate being 100% by mass. In step S13, the amount of acid sites of the catalyst containing zeolite, measured at 250-650°C by ammonia temperature rise desorption method, is 30-800 μmol / g.

Description

Technical Field

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

Background Art

[0002] Olefins, which are the main raw materials for plastics, are usually produced from petroleum. However, recently, technologies for producing olefins from waste plastics have been developed in order to achieve a carbon recycling society. For example, Patent Document 1 discloses a method for producing olefins by thermally decomposing and catalytically decomposing polyolefins as raw materials. In this document, the catalyst used for catalytic decomposition is MFI-type zeolite.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] It is common for plastic products used daily to contain polymers other than polyolefins. In this regard, according to what the inventors have found, when the technology described in Patent Document 1 is used in the case where the raw material is a mixture, the catalytic activity of the zeolite may decrease. Specifically, it has been found that when the technology described in Patent Document 1 is used with a raw material in which polyethylene terephthalate is mixed into polyolefin, the catalytic activity decreases depending on the amount of acid sites of the zeolite.

[0005] One aspect of the present invention aims to provide a method for producing olefins that can reduce the decrease in the catalytic activity of zeolite even when using polyolefins containing polyethylene terephthalate as raw materials.

Means for Solving the Problems

[0006] The present invention includes the following embodiments. <1> A method for producing an olefin, comprising the following steps S12 and S13, Step S12: A step of obtaining hydrocarbons by thermally decomposing raw materials containing polyolefin and polyethylene terephthalate; Step S13: A step of catalytically decomposing the above hydrocarbon with a catalyst containing zeolite to obtain an olefin; Here, In step S12 described above, the content of polyethylene terephthalate in the raw materials is 0.1% by mass or more, with the total content of polyolefin and polyethylene terephthalate being 100% by mass. In step S13 described above, the amount of acid sites in the catalyst containing the zeolite, measured at 250-650°C by ammonia temperature-controlled desorption, is 30-800 μmol / g. A method for producing olefins. <2> The hydrocarbon obtained in step S12 above is a gas and / or liquid. <1> The manufacturing method described above. <3> The olefin obtained in step S13 above contains one or more selected from the group consisting of ethylene, propylene, butene, and pentene. <1> or <2> The manufacturing method described above. <4> In step S13 described above, the zeolite has an MFI structure. <1> ~ <3> A manufacturing method described in any of the following. <5> In step S13 described above, the zeolite contains phosphorus. <1> ~ <4> A manufacturing method described in any of the following. <6> The above process S13 is carried out under the following conditions (i) and (ii): <1> ~ <5> Manufacturing method as described in any of the following: (i) It is in the coexistence with the carrier gas supplied to the reaction system; (ii) The reaction temperature is 400 to 800 °C. <7> The carrier gas is steam and / or nitrogen gas. The production method according to <6>. <8> When the flow rate of the hydrocarbon supplied to the step S13 is taken as 1, the flow rate of the carrier gas is 0.05 to 1.0 in parts by mass. The production method according to <6> or <7>.

Effect of the Invention

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

Brief Description of the Drawings

[0008] [Figure 1] It is a flowchart showing an example of the production method according to one aspect of the present invention. [Figure 2] It is a block diagram showing an implementation example of the production method according to one aspect of the present invention.

Embodiment for Carrying Out the Invention

[0009] One embodiment of the present invention will be described below. However, the present invention is not limited to each configuration described below. The present invention can be variously modified within the scope shown in the claims. The technical scope of the present invention also extends to embodiments or examples obtained by appropriately combining a plurality of technical means disclosed in this specification. At this time, the plurality of technical means may be disclosed over a plurality of embodiments or examples.

[0010] Unless otherwise specified in this specification, "A to B" representing a numerical range is intended to mean "A or more and B or less".

[0011] 〔1. Method for Producing Olefin〕 Hereinafter, a method for producing an olefin according to an aspect of the present invention will be described while referring to exemplary FIG. 1. In the production method shown in FIG. 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 rich in olefins (particularly lower olefins having 2 to 5 carbon atoms). Hereinafter, each step will be described in detail.

[0013] [1.1. Step S11: Pretreatment] In step S11, the plastic is pretreated. The pretreated plastic becomes a feedstock M mainly containing polyolefin and is sent to step S12. The plastic supplied to step S11 is, for example, waste plastic and contains polyolefin (such as polyethylene, polypropylene, etc.). Comparing the plastic supplied to step S11 with the feedstock M sent to step 12, usually the latter has a higher polyolefin content.

[0014] The content of polyolefin in the plastic supplied to step S11 may be 60% by mass or more, 80% by mass or more, or 90% by mass or more, with the total amount of the plastic being 100% by mass. The content of polyolefin in the feedstock M may be 80% by mass or more, 90% by mass or more, or 95% by mass or more, with the total amount of the feedstock M being 100% by mass.

[0015] The supply material M contains polyethylene terephthalate in addition to polyolefin. The lower limit of the polyethylene terephthalate content in supply material 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 the total content of polyolefin and polyethylene terephthalate as 100% by mass. The upper limit of the polyethylene terephthalate content in supply material M may be 25% by mass or less, 20% by mass or less, or 15% by mass or less, based on the total content of polyolefin and polyethylene terephthalate as 100% by mass. Furthermore, the lower limit of the polyethylene terephthalate content in supply material 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 the total amount of supply material M as 100% by mass. The upper limit of the polyethylene terephthalate content in the supply M may 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, with the total content of polyolefin and polyethylene terephthalate being 100% by mass.

[0016] [1.2.Step S12: Pyrolysis] In step S12, the feed material M is thermally decomposed. The first product P1 obtained by thermal decomposition mainly contains hydrocarbons and is sent to step S13. The number of carbon atoms in the hydrocarbons contained in the first product P1 may be 1 to 30. The average number of carbon atoms in the hydrocarbons contained in the first product P1 may be 8 to 30. The hydrocarbons contained in the first product P1 may be gases, liquids, or mixtures 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 thermal decomposition temperature in process S12 may be set based on the composition of the feed material M. A higher thermal decomposition temperature results in a faster decomposition rate of the plastic, but if it is too high, it will carbonize. Taking this into consideration, the upper limit of the thermal decomposition temperature may be 800°C or less, 595°C or less, or 550°C or less. The lower limit of the thermal decomposition 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, a hydrocarbon-containing liquid and / or lower paraffin gas in step S14, and fuels introduced from outside the system (natural gas, kerosene, etc.). Alternatively, at least a portion of the heat source required in step 12 may be supplied by electric heating or microwave irradiation.

[0019] The heating method may be either direct heating or indirect heating. An example of direct heating is a method in which microwave energy is directly supplied to the supply M via a microwave-absorbing material (susceptor). Examples of indirect heating include a method in which heat obtained by an electric heater or combustion is supplied via the heat transfer surface of the device, a method in which high-temperature gas (such as steam, nitrogen gas, or CO2 gas) is introduced into the device, or a method in which high-temperature solid particles (mainly composed of iron, iron oxide, alumina, silica, etc.) are introduced into the device. For preheating the gas or solid particles introduced into the device, the same device used in process S12 may be used, or a device combined with the device used in process S12 may be used. The gas or solid particles introduced into the device may be circulated.

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

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

[0022] Step S12 may be carried out in the presence or absence of a carrier gas. A carrier gas is a gas introduced into the reaction system to fluidize the decomposition products. The carrier gas may be introduced in step 12, or in a step prior to step 12. On the other hand, the gases produced in steps S12 and S13 are not included in the carrier gas. Examples of carrier gases include inert gases (such as nitrogen gas and argon gas), 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 concentration of hydrocarbons 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, when the mass of hydrocarbons sent to step S13 is taken as 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, when the mass of hydrocarbons sent to step S13 is taken as 1.

[0024] In the embodiment where step S12 is carried out using a fluidized bed reactor, the greater the amount of fluidized gas, the lower the hydrocarbon concentration in the gas phase, and therefore the easier it is for the decomposed components to vaporize. Based on this, the lower limit of the linear velocity of the fluidized gas in the fluidized bed reactor may 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 fluidized gas in the fluidized bed reactor may 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 supply rate (NmL / min) to the supply rate (g / min) of the feed M supplied 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 supply rate (NmL / min) to the supply rate (g / min) of the feed M supplied 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 fluidizing medium (g) present in the fluidized bed reactor may be 1.0 NmL / g·min or higher, 2.0 NmL / g·min or higher, or 3.0 NmL / g·min or higher. The upper limit of the ratio of the fluidizing gas supply rate (NmL / min) to the amount of fluidizing medium (g) present in the fluidized bed reactor may be 100 NmL / g·min or lower, 50 NmL / g·min or lower, or 25 NmL / g·min or lower.

[0027] [1.3.Step S13: Catalytic cracking] In step S13, the first product P1 is catalytically decomposed in the presence of a catalyst containing zeolite. The second product P2 obtained by catalytic decomposition mainly contains olefins and is sent to step S14. The number of carbon atoms in the olefins contained in the second product P2 can 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 second product P2 may be 32% by mass or more, 35% by mass or more, or 40% by mass or more.

[0029] The catalytic decomposition temperature in step S13 may be set based on the composition of the first product P1. The lower limit of the catalytic decomposition temperature may be 400°C or higher, 450°C or higher, or 500°C or higher. The upper limit of the catalytic decomposition 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 process S13 may be -80kPaG or higher, -10kPaG or higher, or 0kPaG or higher. The upper limit of the gauge pressure may be 1000kPaG or lower, 300kPaG or lower, or 100kPaG or lower.

[0031] Step S13 may be carried out 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 13 or in a step prior to step 13. 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 concentration of olefin 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, when the mass of olefin sent to step S14 is taken as 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, when the mass of olefin sent to step S14 is taken as 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 the value obtained by dividing the mass-based flow rate (g / sec) of the hydrocarbon supplied to step S13 by the mass (g) of the catalyst containing zeolite.

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

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

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

[0037] The lower limit of the amount of acid sites in 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 in 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 ammonia adsorption desorption. An example of a measuring device is the TPD-1-Atw temperature-controlled desorption apparatus (Microtrac-Bell Co., Ltd.). The specific measurement method is as follows (this method was also adopted in the embodiments of this application described later). 1. Weigh out 50 mg of catalyst and flow helium through it at 500°C for 60 minutes. The flow rate should be 50 mL / min. 2. Cool the catalyst to 100°C. Circulate 0.5% ammonia / helium at 100°C for 30 minutes. The flow rate should be 100 mL / min. This will adsorb ammonia onto the catalyst surface. 3. Circulate helium at 100°C for 30 minutes. The flow rate should be 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, the area value is calculated using the absolute calibration curve method. The obtained area force and the amount of ammonia desorbed per unit mass are calculated. This desorbed amount is taken as the amount of acid sites per unit mass of catalyst.

[0039] The catalyst used in step S13 may contain components other than zeolite. Examples of such components include carriers and binders (matrix materials). Examples of carriers include silica, alumina, silica-alumina, silica-titania, silica-tria, silica-magnesia, silica-gyronia, silica-beryllia, and ternary compositions of silica and other refractory oxides. Examples of binders (matrix materials) include viscous materials (montmorillonite, kaolin, bentonite, halloysite, dickite, nacrite, anaxite, etc.). In the catalyst used in step S13, the mass percentage of zeolite may be 50% by mass or more, 70% by mass or more, or 90% by mass or more. In one embodiment, the catalyst used in step S13 consists only of zeolite.

[0040] (Method of manufacturing zeolite) The zeolite used in step S13 can be manufactured by conventional methods. Below is an example of a method for manufacturing MFI-type zeolite. MFI-type zeolite can be manufactured by crystallizing a mixture containing a silicon source, an aluminum source, a mold agent, and an alkali metal source. Here, the mold agent is a substance that forms a pore structure in crystalline aluminosilicate.

[0041] The silicon source may be a conventionally known silica-containing material used in the production of zeolites. Specific examples of silica-containing materials include tetraethyl orthosilicate, colloidal silica, silica gel powder, and silica hydrogel.

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

[0043] The mold agent may be any conventionally known mold agent used in MFI-type zeolite synthesis. Specific examples of mold agents include tetrapropylammonium salt, tetraethylammonium salt, propanolamine, ethanolamine, n-propylamine, morpholine, 1,5-diaminopentane, 1,6-diaminohexane, dipropylenetetramine, and triethylenetetramine. Among these mold agents, tetrapropylammonium salt is preferred.

[0044] Examples of alkali metal sources 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 sodium-containing compound. Examples of sodium-containing compounds include those containing sodium as a countercation. More specifically, these include sodium hydroxide, sodium chloride, sodium bromide, sodium sulfate, sodium silicate, and sodium aluminate.

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

[0047] The ratio of moles of silicon atoms to moles of aluminum atoms in the mixture before crystallization can range from 10 to 1000.

[0048] The number of moles of the mold agent, alkali source, and water contained in the mixture before crystallization is preferably within the following range, assuming that the number of moles of silicon atoms is 1. • Mold agent: 0.02~5.0 • Alkaline source: 0.01~0.2 ·Wed: 2~100

[0049] MFI-type zeolite can be prepared by crystallizing the above-mentioned 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-type zeolite obtained by crystallization is usually washed and then dried. The drying temperature is, for example, 100°C to 150°C. The dried MFI-type zeolite may be further calcined. The calcination temperature is, for example, 300°C to 700°C.

[0050] For example, the amount of acid sites in MFI-type zeolite can be altered by adding phosphorus. Generally, a higher phosphorus content tends to result in a lower amount of acid sites. To add phosphorus to MFI-type zeolite, a phosphorus source may be added to the mixture before crystallization, or the crystallized MFI-type zeolite may be calcined together with the phosphorus source. Examples of phosphorus sources include phosphates.

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

[0052] Examples of ammonium salts include ammonium salts of inorganic acids (ammonium sulfate, ammonium hydrogen sulfate, ammonium carbonate, ammonium bicarbonate, 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 ammonium salt with MFI-type zeolite. The mixing temperature is, for example, 50°C to 200°C. The mixing time is, for example, 1 to 48 hours. The MFI-type zeolite with reduced alkali source is usually washed and then dried. The drying temperature is, for example, 60°C to 150°C. The dried MFI-type zeolite may be further calcined. The calcination temperature is, for example, 300°C to 700°C.

[0054] [1.4.Step S14: Purification] In step S14, the secondary product P2 is purified. In one embodiment, in step S14, the secondary product P2 is separated into olefins and other hydrocarbons (such as paraffins). In one embodiment, in step S14, olefins with fewer 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). Step S14 separates an olefin-rich gas that is rich in olefins. The olefin content in the olefin-rich gas may be 90% by mass or more. The olefin-rich gas may contain one or more substances 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. This configuration can further improve the yield of olefins.

[0056] Alternatively, at least a portion of the components other than the olefin-rich gas separated in step S14 may be burned and used as a heat source in step S12 or step S13. Such a configuration can reduce the environmental impact of the olefin manufacturing method.

[0057] [2. Olefin Manufacturing System] The olefin manufacturing method described above can be implemented by the olefin manufacturing system illustrated in Figure 2. The manufacturing system 100 shown in Figure 2 comprises a pre-processing unit 10, a thermal decomposition unit 21, a catalytic decomposition unit 22, and a purification unit 30. These components are connected by pathways L1 to L4.

[0058] Plastics such as waste plastics are supplied to the pre-processing unit 10 from the path L1. The discharge port of the pre-processing unit 10 is connected to the pyrolysis unit 21 by the path L2. The plastic supplied to the pre-processing unit 10 is pre-treated to become feed material M, which is supplied to the pyrolysis unit 21 via the path L2. The discharge port of the pyrolysis unit 21 is connected to the supply port of the catalytic cracking unit 22 by the path L3. The feed material M supplied to the pyrolysis unit 21 is pyrolyzed to become the first product P1, which is supplied to the catalytic cracking unit 22 via the path L3. The catalytic cracking unit 22 and the purification unit 30 are connected by the path L4. The first product P1 supplied to the catalytic cracking unit 22 is catalytically cracked to become the second product P2, which is supplied to the purification unit 30 via the path L4. The second product P2 supplied to the purification unit 30 is purified to become olefin, which is removed from the manufacturing system 100. Each part is described in detail below.

[0059] The pre-treatment unit 10 is a component that pre-treats plastics such as waste plastics to provide a feed material M suitable for decomposition. In other words, process S11 is carried out in the pre-treatment unit 10. The pre-treatment unit 10 may be equipped with multiple devices that perform different processes. For example, the pre-treatment unit 10 may be equipped with 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. A sorting device is a device that sorts polyolefins from plastics such as waste plastics. Examples of sorting devices include optical sorting devices and specific gravity separation devices. A crushing device is a device that crushes plastics. A washing device is a device that washes plastics. A drying device is a device that dries plastics. A melting device is a device that heats plastics to make them liquid. A dechlorination device is a device that removes chlorine contained in plastics.

[0060] The pyrolysis unit 21 is a component that decomposes the feed material M by heating. In other words, process S12 is carried out in the pyrolysis unit 21. The decomposed feed material M becomes a first product P1 containing gaseous and / or liquid hydrocarbons. The pyrolysis unit 21 may also be a device that performs pyrolysis continuously. Specific examples 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. Multiple of the above-mentioned devices may be used as the pyrolysis unit 21. Multiple devices may be connected in parallel or in series.

[0061] The catalytic cracking section 22 is a component that decomposes the first product P1 by contacting it with a catalyst. In other words, step S13 is carried out in the catalytic cracking section 22. The decomposed first product P1 becomes a second product P2 containing an olefin. An example of the catalytic cracking section 22 is a reactor including a fixed bed, a moving bed, or a fluidized bed. Multiple reactors described above may be used as the catalytic cracking section 22. Multiple reactors may be connected in parallel or in series.

[0062] The purification unit 30 is a component that separates and purifies the secondary product P2 to obtain olefin. In other words, step S14 is carried out in the purification unit 30. Examples of the purification unit 30 include a gas-liquid separator and a distillation apparatus. Multiple of the above-mentioned apparatuses may be used as the purification unit 30. Multiple apparatuses may be connected in parallel or in series. [Examples]

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

[0064] [Example 1-1] (Preparation of catalyst) Catalyst A was obtained by calcining 1 g of ammonium-type ZSM-5 (CBV28014, Zeolyst) in a muffle furnace. The calcination conditions were an air atmosphere, 550°C, and 5 hours. The amount of acid sites (solid acid content) of catalyst A, measured at 250-650°C by ammonia thermal desorption, 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 (Sumikasen 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 cooling trap was connected further downstream of the downstream reaction tube. A 5L gas bag was connected further downstream of the cooling trap. 3. The catalyst was pretreated by heating only the downstream reaction tube at 550°C for 1 hour while circulating nitrogen gas from the upstream side of the reaction tube (flow rate: 10 mL / min). Next, the downstream reaction tube was cooled to 525°C. 4. While circulating nitrogen gas (flow rate: 10 mL / min), the upstream reaction tube was heated to 455°C to thermally decompose the sample into hydrocarbons. The resulting hydrocarbons were supplied to the downstream reaction tube and brought into contact with the catalyst at 525°C for catalytic decomposition. 5. Of the catalytic decomposition products obtained 103 minutes after the start of heating of the raw materials, the liquid products were recovered using a cooling trap, and the gaseous products were recovered using a gas bag.

[0066] Analysis of the liquid and gaseous catalytic decomposition products by gas chromatography revealed that the yield of olefins with 2 to 5 carbon atoms was 50.6%, relative to the mass of polyethylene used as the raw material.

[0067] [Examples 1-2] (Preparation of catalyst) Catalyst B was prepared according to the following procedure. 1. A 200 mL PTFE inner cylinder was filled with 16.4 g of tetrapropylammonium hydroxide aqueous solution (22.3% by mass), 15.0 g of tetraethyl orthosilicate, and 4.1 g of deionized water. Next, the inner cylinder was loaded into a SUS autoclave. 2. The contents of the container were homogenized at room temperature. Next, it was heated at 80°C for 24 hours while stirring. 3. After cooling the contents of the container, the entire volume was transferred to a glass flask. Next, the contents of the flask were evaporated using an evaporator at 80°C for 2 hours. 4. The entire contents of the mixture remaining in the flask were transferred to a PTFE container, and 0.18 g of aluminum nitrate nonahydrate, 0.29 g of sodium hydroxide, and 0.60 g of deionized water were added. Next, the contents of the container were uniformly stirred using a stirring bar at room temperature. 5. The entire volume of the obtained mixture was transferred to a 200 mL PTFE inner cylinder container. Next, the inner cylinder container was loaded into a SUS autoclave. 6. The cylindrical container was heated at 170°C for 24 hours. Then, it was cooled in ice water. 7. The resulting suspension was centrifuged and the supernatant was removed. Water was added to the precipitated residue to resuspend it, and the supernatant was removed again by centrifuging. This procedure was repeated until the pH of the supernatant was 8 or below. 8. The precipitated residue was dried at 120°C for 8 hours. 9. The obtained solid was ground in a mortar. Next, the ground material was calcined in a muffle furnace. The calcination conditions were an air atmosphere, 550°C, and 6 hours. In this way, 2.9 g of calcined material was obtained. 10. 2.0 g of the calcined body and 100 mL of ammonium nitrate aqueous solution (0.5 M) were placed in a plastic container and allowed to stand at 60°C for 6 hours. Next, the resulting mixture was filtered by suction using a Buchner funnel to recover the solid content. This treatment with ammonium nitrate was repeated a total of three times. 11. The collected solids were washed with 150g of water. Then, they were 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 content) of catalyst B, measured at 250-650°C by ammonia thermal desorption, was 89 μmol / g.

[0068] (Olefin production) The following modifications were made to the olefin production method of Example 1-1. Otherwise, the olefin was produced in the same manner as in Example 1-1. In step 1, the catalyst packed into the downstream reaction tube was changed from catalyst A to catalyst B. In step 5, the recovery time for catalytic decomposition products was changed from 103 minutes to 102 minutes from the start of heating of the raw materials.

[0069] Analysis of the liquid and gaseous catalytic decomposition products by gas chromatography revealed that the yield of olefins with 2 to 5 carbon atoms was 53.5%, relative to the mass of polyethylene used as the raw material.

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

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

[0072] Analysis of the liquid and gaseous catalytic decomposition products by gas chromatography revealed that the yield of olefins with 2 to 5 carbon atoms was 51.0%, relative to the mass of polyethylene used as the raw material.

[0073] [Examples 1-4] (Preparation of catalyst) Catalyst D was prepared according to the following procedure. 1. Add 12.0 g of deionized water and 0.03 g of diammonium hydrogen phosphate to a glass round-bottom flask and stir at room temperature for 5 minutes. Next, add 5.0 g of ammonium type ZSM-5 (CBV28014, Zeolyst) to the flask. 2. The deionized water in the flask was evaporated using an evaporator at 60°C for 2 hours. 3. The entire residue was transferred to a magnetic 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 content) of catalyst D, measured at 250-650°C by ammonia thermal desorption, was 57 μmol / g.

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

[0075] Analysis of the liquid and gaseous catalytic decomposition products by gas chromatography revealed that the yield of olefins with 2 to 5 carbon atoms was 55.7%, relative to the mass of polyethylene used as the raw material.

[0076] [Examples 1-5] (Preparation of catalyst) 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 materials packed into the upstream reaction tube was changed to 0.90 g of polyethylene (Sumikasen G201F, Sumitomo Chemical Co., Ltd.) and 0.10 g of polyethylene terephthalate (Teijin Limited) (polyethylene terephthalate content: 10% by mass). Otherwise, the olefin was produced in the same manner as in Example 1-1.

[0078] Analysis of the liquid and gaseous catalytic decomposition products by gas chromatography revealed that the yield of olefins with 2 to 5 carbon atoms was 37.9%, relative to the mass of polyethylene used as the raw material.

[0079] [Examples 1-6] (Preparation of catalyst) 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 materials packed into the upstream reaction tube was changed to 0.85 g of polyethylene (Sumikasen G201F, Sumitomo Chemical Co., Ltd.) and 0.15 g of polyethylene terephthalate (Teijin Limited) (polyethylene terephthalate content: 15% by mass). Otherwise, the olefin was produced in the same manner as in Example 1-1.

[0081] Analysis of the liquid and gaseous catalytic decomposition products by gas chromatography revealed that the yield of olefins with 2 to 5 carbon atoms was 33.6%, relative to the mass of polyethylene used as the raw material.

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

[0083] (Olefin production) The following modifications were made to the olefin production method of Example 1-1. Otherwise, the olefin was produced in the same manner as in Example 1-1. In step 1, the catalyst packed into the downstream reaction tube was changed from catalyst A to catalyst B. In step 1, the composition of the raw materials packed into the upstream reaction tube was changed to 0.90 g of polyethylene (Sumikasen 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 for catalytic decomposition products was changed from 103 minutes to 102 minutes from the start of heating of the raw materials.

[0084] Analysis of the liquid and gaseous catalytic decomposition products by gas chromatography revealed that the yield of olefins with 2 to 5 carbon atoms was 39.6%, relative to the mass of polyethylene used as the raw material.

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

[0086] (Olefin production) The following modifications were made to the olefin production method of Example 1-1. Otherwise, the olefin was produced in the same manner as in Example 1-1. In step 1, the catalyst packed into the downstream reaction tube was changed from catalyst A to catalyst B. In step 1, the composition of the raw materials packed into the upstream reaction tube was changed to 0.85 g of polyethylene (Sumikasen 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 for catalytic decomposition products was changed from 103 minutes to 102 minutes from the start of heating of the raw materials.

[0087] Analysis of the liquid and gaseous catalytic decomposition products by gas chromatography revealed that the yield of olefins with 2 to 5 carbon atoms was 33.3%, relative to the mass of polyethylene used as the raw material.

[0088] [result] The results of Example 1 are shown in Table 1. Note that the order of entries in Table 1 differs from that of the above example for ease of comparison. [Table 1]

[0089] In Examples 1-1 to 1-3 and Comparative Examples 1-1 to 1-2, experiments were conducted by varying the amount of acid sites in the catalyst. As can be seen from these results, the amount of acid sites in the catalyst affects the yield of olefins with 2 to 5 carbon atoms. Specifically, to increase the yield, for example, the amount of acid sites in the catalyst should 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 using a zeolite with the amount of acid sites adjusted in this way as a catalyst, olefins could be successfully produced by the manufacturing method according to one embodiment of the present invention.

[0091] In Examples 1-5 to 1-8, the polyethylene terephthalate content in the raw materials was increased. Although the yield of olefins with 2 to 5 carbon atoms tended to decrease as the content increased, a sufficient yield could still be maintained according to the manufacturing method of one embodiment of the present invention.

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

[0093] (Preparation of catalyst) 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 were prepared, connected in series. The downstream reactor was filled with 2g of catalyst A. A cooling trap was connected further downstream of the downstream reactor. A gas bag was connected further downstream of the cooling trap. 2. Mixed plastic (flow rate: 0.4 g / min) and nitrogen gas (flow rate: 0.06 g / min) were supplied to the upstream reactor heated to 550°C and thermally decomposed. The composition of the mixed plastic was as follows. The proportion of polyethylene terephthalate, shown as polyolefin and polyethylene terephthalate, was 3.3% by mass. 45 parts by mass of polyethylene (Sumikasen G201F, Sumitomo Chemical Co., Ltd.) • 44 parts by mass of polypropylene (Nobren FS2011DG3, Sumitomo Chemical Co., Ltd.) • 3 parts by mass of polyethylene terephthalate (Teijin Limited) • 4 parts by mass of polystyrene (Goodfellow Inc.) 0.5 parts by mass of polyvinyl chloride (Shin-Etsu Chemical Co., Ltd.) 0.5 parts by mass of polyvinylidene chloride (Goodfellow Inc.) • 3 parts by mass of nylon 6 (UBE Corporation) 3. The entire amount of reaction products and steam (flow rate: 0.1 g / min) from the upstream reactor were supplied to the downstream reactor, which was heated to 525°C. This caused catalytic cracking of the hydrocarbons produced by thermal decomposition. 4. Of the catalytic decomposition products obtained between 1 hour 15 minutes and 1 hour 30 minutes after the start of supplying the mixed plastic, the liquid products were recovered using a cooling trap. In addition, of the catalytic decomposition products obtained between 1 hour 20 minutes and 1 hour 30 minutes after the start of supplying the mixed plastic, the gaseous products were recovered using a gas bag.

[0095] Analysis of the liquid and gaseous catalytic decomposition products by gas chromatography revealed that the yield of olefins with 2 to 5 carbon atoms was 51.9%, relative to the mass of the mixed plastic supplied as raw material.

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

[0097] This invention can be used in the production of olefins.

Claims

1. A method for producing an olefin, comprising the following steps S12 and S13, Step S12: A step of obtaining hydrocarbons by thermally decomposing raw materials containing polyolefin and polyethylene terephthalate; Step S13: A step of catalytically decomposing the above hydrocarbon with a catalyst containing zeolite to obtain an olefin; Here, In step S12 described above, the content of polyethylene terephthalate in the raw materials is 0.1% by mass or more, with the total content of polyolefin and polyethylene terephthalate being 100% by mass. In step S13 described above, the amount of acid sites in the catalyst containing the zeolite, measured at 250 to 650°C by the ammonia temperature-controlled desorption method, is 30 to 800 μmol / g. A method for producing olefins.

2. The hydrocarbon obtained in step S12 above is a gas and / or liquid. The manufacturing method according to claim 1.

3. The olefin obtained in step S13 above contains one or more selected from the group consisting of ethylene, propylene, butene, and pentene. The manufacturing method according to claim 1 or 2.

4. In step S13 described above, the zeolite has an MFI structure. The manufacturing method according to claim 1 or 2.

5. In step S13 described above, the zeolite contains phosphorus. The manufacturing method according to claim 1 or 2.

6. The manufacturing method according to claim 1 or 2, wherein step S13 above is carried out under conditions satisfying (i) and (ii) below: (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 mentioned above is water vapor and / or nitrogen gas. The manufacturing method according to claim 6.

8. The flow rate of the carrier gas is 0.05 to 1.0 in mass parts, where the flow rate of the hydrocarbon supplied to step S13 is 1. The manufacturing method according to claim 6.

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