JP-7856866-B1 - Method for producing olefins

Abstract

[Problem] The problem 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. [Selection Diagram] None

Inventors

• 猪股 海渡
• 吉井 政之

Assignees

• 住友化学株式会社

Dates

Publication Date

20260511

Application Date

20260305

Claims (8)

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 a catalytic cracking step of catalytically 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, wherein the H-type zeolite has 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 method for producing an olefin according to claim 1, 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 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 performed by contact 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 performed 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.

Description

This invention relates to a method for producing olefins. In recent years, the recycling and reuse of plastics has attracted attention from the perspective of resource recovery. For example, reuse, material recycling, and chemical recycling are being employed to recycle waste plastics. Chemical recycling, in particular, has the potential to overcome the limitations of performance degradation caused by recycling, as it chemically decomposes plastics and can be recycled into petrochemical raw materials. As one example of chemical recycling technology, Patent Document 1 discloses a method for obtaining lower olefins by catalytic cracking polyolefins in the presence of a catalyst containing an MFI-type zeolite. International Publication No. 2022/039094 The following describes embodiments of the present invention, but the present invention is not limited to these embodiments. <Method for manufacturing H-type zeolite> The method for producing H-type zeolite in the olefin production method according to this embodiment 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. Furthermore, the method for producing H-type zeolite includes a harmful gas detection step of detecting any remaining harmful gases after the harmful gas removal step. (Firing process) 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. The supply amount of the aforementioned supply gas is not particularly limited, and is usually between 0.001 m³ /h and 1000 m³ /h. 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. 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. 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 IZA (International Zeolite Association) structural code, specifically H + -ZSM-5. The presence of an MFI structure in a zeolite can be confirmed by analysis using X-ray diffraction. H-type zeolite having an MFI structure can be obtained by calcining NH₄ - type zeolite having an MFI structure. NH₄ - type zeolite 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 and exchanging cations ( Na⁺ ) with NH₄⁺ . Examples of ammonium salts include ammonium salts of inorganic acids such as ammonium sulfate, ammonium bisulfate, 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. 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 used to impart a pore structure to the zeolite. 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 powder, silica hydrogel, and sodium silicate. 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. As a molding agent, known molding agents used in the synthesis of zeolites having an MFI structure can be used. Examples of molding agents include tetrapropylammonium salt, tetraethylammonium salt, propanolamine, ethanolamine, n-propylamine, morpholine, 1,5-diaminopentane, 1,6-diaminohexane, dipropylenetetramine, and triethylenetetramine. The molding agent is preferably tetrapropylammonium salt (tetrapropylammonium hydroxide). Examples of alkali metal sources include alkali metal hydroxides, alkali metal chlorides, alkali metal bromides, and alkali metal sulfides. Examples of alkali metals include sodium and potassium. When the alkali met