Method for producing olefins

Abstract

The objective is to provide a method for producing olefins that can obtain H-type zeolite with a stable production volume. [Solution] The present invention provides a method for producing olefins, comprising: a calcination step of obtaining H-type zeolite by calcining NH4-type zeolite in the presence of a supply gas; a harmful gas removal step of removing harmful gases generated in the calcination step; and a harmful gas detection step of detecting any remaining harmful gases after the harmful gas removal step, wherein the amount of supply gas in the calcination step is controlled based on the detection results of the harmful gas detection step, and the method also includes a catalytic cracking step of obtaining olefins by catalytic cracking a hydrocarbon stream obtained by thermally decomposing waste plastic raw materials containing polyolefins in the presence of a catalyst containing H-type zeolite obtained by a method for producing H-type zeolite, wherein the H-type zeolite has an MFI structure.

Description

Technical Field

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

Background Art

[0002] In recent years, the recycling and reuse of plastics have attracted attention from the perspective of resource recovery. For example, processes such as reuse, material recycling, and chemical recycling are being carried out to recycle waste plastics. In particular, chemical recycling can chemically decompose plastics and recycle them into petrochemical raw materials, so it has the potential to break through the limitations of performance degradation due to recycling.

[0003] As one of the chemical recycling technologies, for example, Patent Document 1 discloses a method for obtaining lower olefins by catalytic cracking of polyolefins in the presence of a catalyst containing MFI-type zeolite.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, in the method for producing lower olefins by catalytic cracking of waste plastics, a catalyst containing H-type zeolite is preferably used. H-type zeolite is produced by firing NH4-type zeolite in the presence of supply gases such as air and nitrogen. However, the exhaust gas during firing contains harmful gases such as NOx and NH3, and these harmful gases cannot be emitted into the atmosphere. Therefore, the supply amount of the supply gas is not stable, and as a result, there is a problem that the production amount of H-type zeolite is not stable.

[0006] The present invention has been made in view of such problems, and an object thereof is to provide a method for producing an olefin capable of obtaining H-type zeolite with a stable production amount.

Means for Solving the Problems

[0007] The method for producing an olefin according to the present invention includes a firing step of firing NH4-type zeolite to obtain H-type zeolite in the presence of a supply gas, a harmful gas removal step of removing harmful gases generated in the firing step, and a harmful gas detection step of detecting residual harmful gases after the harmful gas removal step. Based on the detection result of the harmful gas detection step, the supply amount of the supply gas in the firing step is controlled. The method further includes a catalytic cracking step of catalytically cracking a hydrocarbon stream obtained by thermally decomposing a waste plastic raw material containing polyolefin in the presence of a catalyst containing H-type zeolite obtained by the method for producing H-type zeolite, wherein the H-type zeolite has an MFI structure.

Effects of the Invention

[0008] According to the present invention, it is possible to provide a method for producing an olefin capable of obtaining H-type zeolite with a stable production amount.

Modes for Carrying Out the Invention

[0009] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to the following embodiments.

[0010] <Method for Producing H-Type Zeolite> The method for producing H-type zeolite in the method for producing an olefin according to the present embodiment includes a firing step of firing NH4-type zeolite to obtain H-type zeolite in the presence of a supply gas, and a harmful gas removal step of removing harmful gases generated in the firing step. Further, the method for producing H-type zeolite includes a harmful gas detection step of detecting residual harmful gases after the harmful gas removal step.

[0011] (Firing Step) The supply gas preferably comprises at least one selected from the group consisting of oxygen, nitrogen, water, argon, and helium, and more preferably comprises oxygen or nitrogen.

[0012] The amount of the supply gas is not particularly limited, and is typically 0.001 m³. 3 / h or more 1000m 3 It is less than or equal to / h.

[0013] From the viewpoint of efficiently obtaining H-type zeolite, the firing temperature is preferably 500°C to 900°C, and more preferably 600°C to 800°C. Furthermore, from the viewpoint of efficiently obtaining H-type zeolite, the firing time is preferably 0.01 hours to 100 hours, and more preferably 0.1 hours to 10 hours.

[0014] Examples of the aforementioned H-type zeolite include beta-type zeolite, faujasite-type zeolite, L-type zeolite, ferrielite-type zeolite, mordenite-type zeolite, and MFI-type zeolite.

[0015] The aforementioned H-type zeolite is an MFI-type zeolite, that is, it has an MFI structure. An H-type zeolite having an MFI structure refers to a crystalline aluminosilicate having an MFI structure according to the structural code of the IZA (International Zeolite Association), and specifically, H + -ZSM-5. The presence of an MFI structure in the zeolite can be confirmed by analysis using X-ray diffraction.

[0016] H-type zeolites having an MFI structure are obtained by calcining NH4-type zeolites having an MFI structure. NH4-type zeolites having an MFI structure can be obtained, for example, by contacting a zeolite having an MFI structure with an aqueous solution of an ammonium salt, thereby generating cations (Na). + ) to NH 4+ It is obtained by ion exchange.

[0017] Examples of ammonium salts include ammonium salts of inorganic acids such as ammonium sulfate, ammonium hydrogen sulfate, ammonium carbonate, ammonium bicarbonate, diammonium hydrogen phosphate, diammonium hydrogen phosphate, ammonium phosphate, ammonium hydrogen pyrophosphate, ammonium pyrophosphate, ammonium chloride, and ammonium nitrate, as well as ammonium salts of organic acids such as ammonium acetate. The ammonium salt is preferably ammonium sulfate, ammonium chloride, or ammonium nitrate.

[0018] The following describes a method for producing zeolite having an MFI structure. Zeolite having an MFI structure is obtained by preparing a mixture containing a silicon source, an aluminum source, a mold agent, and an alkali metal source, and then crystallizing it. Here, "mold agent" refers to a substance that imparts a pore structure to the zeolite.

[0019] As a silicon source, known silicon sources used in the production of various zeolites can be used. Examples of silicon sources include tetraethyl orthosilicate, colloidal silica, silica gel dry powder, silica hydrogel, and sodium silicate.

[0020] As the aluminum source, known aluminum sources used in the production of various zeolites can be used. Examples of aluminum sources include aluminum nitrate, aluminum chloride, sodium aluminate, aluminum hydroxide, and aluminum alkoxide. The aluminum source is preferably aluminum nitrate or sodium aluminate.

[0021] As the templating agent, known templating agents used in the synthesis of zeolites having an MFI structure can be used. Examples of the templating agent include tetrapropylammonium salts, tetraethylammonium salts, propanolamine, ethanolamine, n-propylamine, morpholine, 1,5-diaminopentane, 1,6-diaminohexane, dipropylenetetramine, triethylenetetramine, and the like. The templating agent is preferably a tetrapropylammonium salt (tetrapropylammonium hydroxide).

[0022] Examples of the alkali metal source include hydroxides of alkali metals, chlorides of alkali metals, bromides of alkali metals, sulfides of alkali metals, and the like. Examples of the alkali metal include sodium, potassium, and the like.

[0023] When the alkali metal is sodium, examples of the sodium source include sodium hydroxide, sodium nitrate, sodium chloride, sodium bromide, sodium sulfate, sodium silicate, sodium aluminate, compounds containing sodium as a counter cation, and the like.

[0024] When the alkali metal is potassium, examples of the potassium source include potassium hydroxide, potassium nitrate, potassium chloride, potassium bromide, potassium sulfate, potassium silicate, potassium aluminate, compounds containing potassium as a counter cation, and the like.

[0025] In the mixture containing a silicon source, an aluminum source, a templating agent, and an alkali metal source, the ratio (Si / Al ratio) of the number of moles of silicon atoms to the number of moles of aluminum atoms is preferably 1 or more, more preferably 100 or more. The ratio may be 10000 or less, preferably 2500 or less.

[0026] In addition, the molar ratio of each component in the mixture containing a silicon source, an aluminum source, a templating agent, and an alkali metal source to the number of moles of silicon atoms preferably satisfies the following requirements. Templating agent: 0.02 or more, 5.0 or less Alkali metal source: 0.01 or higher, 0.2 or lower Water: 2 or more, 100 or less

[0027] Furthermore, the ratio of the number of moles of each component in the mixture containing the silicon source, aluminum source, mold agent, and alkali metal source to the number of moles of silicon atoms more preferably satisfies the following requirements. Molding agent: 0.05 or more, 2.0 or less Alkali metal source: 0.04 or higher, 0.3 or lower Water: 5 or more, 50 or less

[0028] (Harmful gas removal process) In one embodiment, the harmful gas is at least one selected from the group consisting of NOx and NH3. When the harmful gas is NOx and NH3, the concentrations of NOx and NH3 in the gas discharged in the calcination process are, for example, 0.001 ppm by volume or more and 1% by volume or less.

[0029] The harmful gas removal step is carried out, in one embodiment, by contacting the harmful gas with a liquid. Specifically, it is carried out by contacting the harmful gas with a liquid filled in a container. The liquid is preferably at least one selected from the group consisting of water, alkaline aqueous solutions, and acidic aqueous solutions, and more preferably water. Examples of the alkaline aqueous solution include sodium hydroxide aqueous solution, potassium hydroxide aqueous solution, ammonia aqueous solution, sodium carbonate aqueous solution, sodium bicarbonate aqueous solution, and organic amine aqueous solution. From the viewpoint of efficiently removing harmful gases, the alkaline aqueous solution is preferably a sodium hydroxide aqueous solution or a potassium hydroxide aqueous solution. Examples of the acidic aqueous solution include hydrochloric acid, sulfuric acid, nitric acid, acetic acid, phosphoric acid, oxalic acid, and citric acid. From the viewpoint of efficiently removing harmful gases, the acidic aqueous solution is preferably hydrochloric acid or sulfuric acid.

[0030] From the viewpoint of efficiently removing harmful gases, the temperature at which the liquid is brought into contact with the substance is preferably 5°C to 60°C, and more preferably 10°C to 50°C. From the viewpoint of efficiently removing harmful gases, the contact time with the liquid is preferably 1 second to 10 hours, and more preferably 10 seconds to 1 hour.

[0031] The aforementioned harmful gas removal process is carried out in another manner by contacting the harmful gas with an adsorbent. Specifically, it is carried out by bringing the harmful gas into contact with the adsorbent filled in a container. Examples of adsorbents include activated carbon, zeolite, silica gel, ion exchange resin, activated alumina, and metal oxides. Examples of metal oxides include copper oxide and iron oxide.

[0032] From the viewpoint of efficiently removing harmful gases, the temperature at which the adsorbent is in contact with the adsorbent is preferably 5°C to 60°C, and more preferably 10°C to 50°C. From the viewpoint of efficiently removing harmful gases, the contact time with the adsorbent is preferably 1 second to 10 hours, and more preferably 10 seconds to 1 hour.

[0033] If the concentration of NOx and NH3 in the gas generated in the calcination process is 0.001 ppm by volume or more and 1% by volume or less, the harmful gas removal process is preferably carried out by contact with water, from the viewpoint of simplifying the removal operation.

[0034] (Harmful gas detection process) The harmful gas detection step is preferably carried out by at least one method selected from the group consisting of a method for measuring the concentration of the remaining harmful gas and a method for observing the color of the remaining harmful gas.

[0035] In the method for producing the H-type zeolite, the amount of supply gas in the calcination process is controlled based on the detection results of the harmful gas detection process.

[0036] When the aforementioned harmful gas detection step is performed by measuring the concentration of residual harmful gas, specifically, when the measured concentration of harmful gas becomes high, it can be controlled by increasing the supply amount of the supply gas in the calcination step. The concentration of harmful gas is measured using, for example, a gas concentration meter that uses an electrochemical sensor, a semiconductor sensor, or an optical sensor as its detection principle.

[0037] If the aforementioned harmful gas detection step is performed by observing the color of the remaining harmful gas, specifically, if the observed harmful gas exhibits a reddish hue, it can be controlled by increasing the supply amount of the supplied gas in the firing step. The observation of the color of the harmful gas is performed, for example, by visual inspection.

[0038] The method for producing H-type zeolite includes a calcination step of obtaining H-type zeolite by calcining NH4-type zeolite in the presence of a supply gas, and a harmful gas removal step of removing harmful gases generated in the calcination step. By including the harmful gas removal step, the method for producing H-type zeolite can efficiently remove harmful gases generated in the calcination step. As a result, the supply amount of supply gas in the calcination step becomes stable, and H-type zeolite can be obtained in a stable production volume.

[0039] The method for producing H-type zeolite further includes a harmful gas detection step for detecting any remaining harmful gases after the harmful gas removal step, and controls the amount of supply gas in the calcination step based on the detection results of the harmful gas detection step. With this configuration, the amount of supply gas in the calcination step becomes more stable, and thus H-type zeolite can be obtained with a more stable production volume.

[0040] In the method for producing the H-type zeolite, the harmful gas detection step is preferably performed by at least one method selected from the group consisting of a method for measuring the concentration of the remaining harmful gas and a method for observing the color of the remaining harmful gas. With this configuration, the method for producing the H-type zeolite can easily perform the harmful gas detection step.

[0041] In the method for producing the H-type zeolite, the harmful gas may be at least one selected from the group consisting of NOx and NH3. The method for producing the H-type zeolite can efficiently remove harmful gases of this configuration.

[0042] In the method for producing H-type zeolite, the supply gas may contain at least one selected from the group consisting of oxygen, nitrogen, water, argon, and helium. With this configuration, the method for producing H-type zeolite can efficiently produce H-type zeolite.

[0043] In the method for producing the H-type zeolite, the harmful gas removal step is preferably carried out by contact with a liquid. With this configuration, the method for producing the H-type zeolite can efficiently remove harmful gases generated in the calcination step.

[0044] In the method for producing the H-type zeolite, the liquid is preferably at least one selected from the group consisting of water, an alkaline aqueous solution, and an acidic aqueous solution. With this configuration, the method for producing the H-type zeolite can more efficiently remove harmful gases generated in the calcination process.

[0045] In the method for producing the H-type zeolite, the harmful gas removal step is preferably carried out by contacting the zeolite with an adsorbent. With this configuration, the method for producing the H-type zeolite can efficiently remove the harmful gases generated in the calcination step.

[0046] The method for producing the H-type zeolite described above is such that the H-type zeolite has an MFI structure. With this configuration, the method for producing the H-type zeolite can produce an H-type zeolite suitable for the production of olefins.

[0047] <Method for producing olefins> The method for producing olefins according to this embodiment includes a catalytic cracking step in which a hydrocarbon stream obtained by thermally decomposing a waste plastic raw material containing polyolefin in the presence of a catalyst containing H-type zeolite obtained by the above-described method for producing H-type zeolite is catalytically cracked to obtain olefins.

[0048] The aforementioned waste plastic raw materials refer to plastic products that have been used for some end-use. The aforementioned waste plastic raw materials include at least polyolefins.

[0049] Specific examples of polyolefins included in the waste plastic raw material include polyethylene, polypropylene, polybutene, ethylene-vinyl acetate copolymer, ethylene-methyl acrylate copolymer, ethylene-methyl methacrylate copolymer, ethylene-propylene copolymer, ethylene-α-olefin copolymer, and other polyolefin plastics, as well as mixtures of two or more of these. Among these, the polyolefin included in the waste plastic raw material is preferably polyethylene, polypropylene, or ethylene-propylene copolymer.

[0050] In addition to the polyolefin-based plastics mentioned above, the aforementioned waste plastic raw materials may include other components such as polystyrene, polyamide, polyvinyl chloride, polyvinylidene chloride, polycarbonate, polyurethane, polyester, polymethyl methacrylate, acrylonitrile-styrene copolymer, acrylonitrile-butadiene-styrene copolymer, natural rubber, and synthetic rubber.

[0051] The aforementioned waste plastic raw materials may include, for example, industrial products such as molded articles manufactured using the polyolefins and other components mentioned above. Specific examples of industrial products include plastic containers and packaging collected under the Container and Packaging Recycling Law.

[0052] The waste plastic raw material may be in a solid state, as in the molded product described above. The waste plastic raw material may also be used by changing the state of the solid industrial product to a liquid and / or gaseous state, for example, it may be a liquid and / or gaseous mixture of the polyolefin and other components described above.

[0053] The hydrocarbon stream may contain hydrocarbons, oxygen-containing compounds, nitrogen-containing compounds, sulfur-containing compounds, chlorine-containing compounds, and the like.

[0054] Examples of the hydrocarbons mentioned above include alkanes such as methane, ethane, and propane; diolefins such as butadiene; aromatic hydrocarbons such as benzene, toluene, and xylene; and cycloalkanes such as cyclohexane.

[0055] Examples of the oxygen-containing compounds include organic compounds having oxygen functional groups such as carboxyl groups, hydroxyl groups, and ether groups, as well as carbon dioxide and carbon monoxide. Examples of the nitrogen-containing compounds include organic compounds having nitrogen functional groups such as amino groups and isocyanate groups, nitrogen ring compounds, nitric oxide, and nitrogen dioxide. Examples of the sulfur-containing compounds include organic compounds having sulfur functional groups such as thiol groups, thioether groups, and sulfonyl groups, sulfur ring compounds, and hydrogen sulfide. Examples of the chlorine-containing compounds include methyl chloride, chlorine-containing alkanes such as chloroform, and chlorine-containing aromatic compounds.

[0056] In the aforementioned thermal decomposition, the virgin plastic raw material containing polyolefin may be further thermally decomposed. The virgin plastic raw material means a polymer produced by a process including a polymerization step, a resin composition containing said polymer, or a plastic product using said polymer or resin composition that has not been used for any end use. The polyolefin contained in the virgin plastic raw material is the same as the polyolefin contained in the waste plastic raw material.

[0057] From the viewpoint of improving the yield of hydrocarbon flow, the thermal decomposition temperature is usually between 350°C and 550°C, and preferably between 400°C and 500°C.

[0058] The thermal decomposition pressure is typically between 0 MPaG and 5 MPaG, and preferably between 0 MPaG and 0.5 MPaG.

[0059] In the aforementioned pyrolysis, inert gases such as water vapor, nitrogen gas, and CO2 gas may be present.

[0060] The aforementioned thermal decomposition can be carried out using any suitable conventionally known reaction vessel. Examples of materials for the reaction vessel include quartz glass, carbon steel, stainless steel, Inconel alloy, Hastelloy alloy, Incoloy alloy, Monel alloy, and the like.

[0061] The hydrocarbon stream obtained by the aforementioned thermal decomposition typically contains hydrocarbons with approximately 1 to 50 carbon atoms, hydrogen, etc., in liquid, gaseous, or mixed states.

[0062] The H-type zeolite used in the catalytic cracking step is the H-type zeolite obtained by the method for producing H-type zeolite described above.

[0063] The catalytic decomposition temperature is typically between 400°C and 700°C, and preferably between 450°C and 600°C.

[0064] The catalytic decomposition pressure is typically between 0 MPaG and 5 MPaG, and preferably between 0 MPaG and 0.5 MPaG.

[0065] From the viewpoint of reducing the proportion of unreacted hydrocarbon flow, the residence time required for the catalytic cracking step is preferably 1 second or more and 10,000 seconds or less, and more preferably 10 seconds or more and 1,000 seconds or less.

[0066] In the catalytic cracking process, an inert gas such as water vapor, nitrogen gas, or CO2 gas may be present.

[0067] The catalytic cracking step can be carried out using any suitable conventional reaction vessel. Examples of materials for the reaction vessel include quartz glass, carbon steel, stainless steel, Inconel alloy, Hastelloy alloy, Incoloy alloy, Monel alloy, and the like.

[0068] The olefin obtained by the catalytic cracking step is preferably at least one selected from the group consisting of ethylene, propylene, butene, and pentene.

[0069] The olefin production method according to this embodiment includes a catalytic cracking step in which a hydrocarbon stream obtained by thermally decomposing a waste plastic raw material containing polyolefin in the presence of a catalyst containing H-type zeolite obtained by the above-described H-type zeolite production method is catalytically cracked to obtain an olefin. With this configuration, the olefin production method can efficiently produce olefins using H-type zeolite obtained in a stable production volume.

[0070] In the method for producing olefins according to this embodiment, the olefin is at least one selected from the group consisting of ethylene, propylene, butene, and pentene. The method for producing olefins can efficiently produce olefins having such a configuration.

[0071] The present invention includes the following embodiments. [1] A method for producing olefins, comprising: a calcination step of calcining NH4 type zeolite in the presence of a supply gas to obtain H type zeolite; a harmful gas removal step of removing harmful gases generated in the calcination step; and a harmful gas detection step of detecting any remaining harmful gases after the harmful gas removal step, wherein the amount of supply gas in the calcination step is controlled based on the detection results of the harmful gas detection step, and the H type zeolite has an MFI structure, and a catalytic cracking step of catalytically cracking a hydrocarbon stream obtained by thermally decomposing a waste plastic raw material containing polyolefin in the presence of a catalyst containing H type zeolite obtained by a method for producing H type zeolite, wherein the H type zeolite has an MFI structure [2] The method for producing an olefin according to [1], wherein the harmful gas detection step is carried out by at least one method selected from the group consisting of a method for measuring the concentration of the remaining harmful gas and a method for observing the color of the remaining harmful gas. [3] The method for producing an olefin according to [1] or [2], wherein the harmful gas is at least one selected from the group consisting of NOx and NH3. [4] The method for producing an olefin according to any one of [1] to [3], wherein the supply gas comprises at least one selected from the group consisting of oxygen, nitrogen, water, argon, and helium. [5] The method for producing an olefin according to any one of [1] to [4], wherein the harmful gas removal step is carried out by contacting the olefin with a liquid. [6] The method for producing an olefin according to [5], wherein the liquid is at least one selected from the group consisting of water, an alkaline aqueous solution, and an acidic aqueous solution. [7] The method for producing an olefin according to any one of [1] to [4], wherein the harmful gas removal step is carried out by contacting the adsorbent. [8] The method for producing an olefin according to any one of [1] to [7], wherein the olefin is at least one selected from the group consisting of ethylene, propylene, butene, and pentene.

[0072] It should be noted that the method for producing olefins according to the present invention is not limited to the embodiments described above, and various modifications are possible without departing from the spirit of the present invention. Furthermore, configurations, methods, etc., of embodiments other than those described above may be arbitrarily adopted and combined.

Claims

1. In the presence of supply gas, NH ４ A method for producing olefins, comprising: a calcination step of calcining a type zeolite to obtain H-type zeolite; a harmful gas removal step of removing harmful gases generated in the calcination step; and a harmful gas detection step of detecting any remaining harmful gases after the harmful gas removal step, wherein the amount of supply gas in the calcination step is controlled based on the detection results of the harmful gas detection step, and a catalytic cracking step of obtaining olefins by catalytic cracking a hydrocarbon stream obtained by thermally decomposing a waste plastic raw material containing polyolefins in the presence of a catalyst containing H-type zeolite obtained by a method for producing H-type zeolite having an MFI structure.

2. The method for producing an olefin according to claim 1, wherein the harmful gas detection step is performed by at least one method selected from the group consisting of a method for measuring the concentration of the remaining harmful gas and a method for observing the color of the remaining harmful gas.

3. The aforementioned harmful gases are NOx and NH ３ A method for producing an olefin according to claim 1, wherein the method is at least one selected from the group consisting of the following.

4. The method for producing an olefin according to claim 1, wherein the supply gas comprises at least one selected from the group consisting of oxygen, nitrogen, water, argon, and helium.

5. The method for producing an olefin according to claim 1, wherein the harmful gas removal step is carried out by contacting the olefin with a liquid.

6. The method for producing an olefin according to claim 5, wherein the liquid is at least one selected from the group consisting of water, an alkaline aqueous solution, and an acidic aqueous solution.

7. The method for producing an olefin according to claim 1, wherein the harmful gas removal step is carried out by contacting the olefin with an adsorbent.

8. The method for producing an olefin according to claim 1, wherein the olefin is at least one selected from the group consisting of ethylene, propylene, butene, and pentene.