Method for producing light olefins from waste plastics through dehydrogenation and cracking reaction

Abstract

The present invention relates to a method for producing light olefins from waste plastics, comprising: a) pyrolyzing waste plastic raw materials to produce an oil-containing stream; b) reacting part or all of the oil-containing stream in one or more reactors in the presence of a catalyst; and c) separating and recovering light olefins from the reaction product, wherein in step b), the catalyst comprises a dehydrogenation catalyst and a cracking catalyst.

Description

Technology Field

[0001] The present invention relates to a method for producing light olefins from waste plastics through dehydrogenation and cracking reactions. Background Technology

[0003] Light olefins refer to ethylene, propylene, and butene obtained from naphtha cracking, serving as essential basic raw materials for the petrochemical industry for the manufacture of various chemical products such as synthetic resins, synthetic rubber, and alcohols. While light olefins are primarily produced through the thermal cracking of petroleum-derived naphtha, this method involves high-temperature reactions exceeding 850°C, resulting in high energy consumption and the generation of large amounts of greenhouse gases. Therefore, there is a need for energy-efficient technologies that produce light olefins using sustainable materials, such as waste plastics.

[0004] Meanwhile, polyolefin plastics, such as polyethylene and polypropylene, which are widely used as packaging materials, account for more than 60% of global waste plastic generation due to their short product lifespans. The mechanical recycling of these waste plastics is currently difficult to apply widely due to impurities originating from other plastics, additives, and fillers. Furthermore, waste disposal methods such as landfilling and incineration are unsuitable approaches as they are prone to causing environmental pollution. Therefore, to reduce the negative environmental impact of existing waste plastic disposal methods and transition to a circular economy with low carbon emissions, it is necessary to develop a new energy-efficient process that converts waste plastics into valuable light olefins.

[0005] Accordingly, methods for producing light olefins by reacting pyrolysis oil generated from the pyrolysis of waste plastics in the presence of a catalyst are being actively developed. Compared to conventional catalystless pyrolysis reactions, the catalytic decomposition reaction of waste plastic pyrolysis oil is a promising alternative that can overcome problems that may arise during the process of producing light olefins from waste plastic pyrolysis oil. Catalytic decomposition reactions have the advantage of being able to utilize waste plastic pyrolysis oil composed of a wide range of carbon numbers containing a large amount of olefins as a raw material, and enabling the production of light olefins with high yield while consuming relatively little energy. Zeolite-based catalysts, particularly ZSM-5, are known to be excellent as cracking catalysts for waste plastic pyrolysis oil. However, at low temperatures, paraffins composed of C9 or lower in waste plastic pyrolysis oil are not easily decomposed on the cracking catalyst, and even if decomposition occurs, there is a problem of low selectivity for light olefins.

[0006] Therefore, to selectively produce high-yield light olefins at low temperatures, a technology is required to first convert low-reactivity paraffins into relatively high-reactivity olefins through a dehydrogenation reaction and then crack them; this necessitates securing an optimal catalyst, catalyst arrangement, and optimal operating conditions (reaction temperature, space velocity, etc.). Prior art literature

[0008] Korean Patent Publication No. 10-2022-0117899 (August 24, 2022) The problem to be solved

[0009] The present invention provides a method for producing light olefins from waste plastics in the presence of a dehydrogenation catalyst and a cracking catalyst. means of solving the problem

[0011] The method for producing light olefins from waste plastics through dehydrogenation and cracking reactions according to the present invention comprises: a) a step of pyrolyzing waste plastic raw materials to produce an oil-containing stream; b) a step of reacting part or all of the oil-containing stream in one or more reactors in the presence of a catalyst; and c) a step of separating and recovering light olefins from the reaction products; wherein in step b), the catalyst may include a dehydrogenation catalyst and a cracking catalyst.

[0012] The above oil-containing stream may comprise 1 to 80 weight% olefins, 1 to 50 weight% aromatic hydrocarbons, and 1 to 50 weight% hydrocarbons in the naphtha region composed of C5-C9 hydrocarbons.

[0013] The above oil-containing stream may include one or more non-hydrocarbon substances selected from the group consisting of nitrogen component substances, sulfur component substances, oxygen component substances, and halogen component substances.

[0014] The above oil-containing stream may contain 100 to 7000 ppm of nitrogen, 10 to 3000 ppm of sulfur, 0.01 to 4 weight% of oxygen, and 1 to 5000 ppm of halogen.

[0015] The above dehydrogenation catalyst may be a composite catalyst in which an active metal is supported on a carrier.

[0016] The active metal of the above dehydrogenation catalyst may be Co, Cr, Pt, or a mixture thereof.

[0017] The active metal for the above dehydrogenation may further include B, Ce, La, Zr, Zn, Sn, Re, Ga, or a mixture thereof.

[0018] The support of the above dehydrogenation catalyst may be alumina, silica, titanine, zirconia, carbon, alkaline earth metal oxide, alkali metal oxide, silica-alumina, silicon carbide, niobia, aluminum phosphate, alumina hydrate, zeolite, clay, SAPO (silica-alumina-phosphate), ALPO (aluminum phosphate), MOF (Metal Organic Framework), amorphous silica-alumina, or a mixture thereof.

[0019] The cracking catalyst may be zeolite, clay, SAPO (silica-alumina-phosphate), ALPO (aluminum phosphate), MOF (Metal Organic Framework), amorphous silica-alumina, or a mixture thereof.

[0020] The zeolite of the cracking catalyst above may include one or more selected from the group consisting of ZSM-5, ZSM-11, ZSM-12, ZSM-22, ZSM-23, ZSM-48, zeolite X, zeolite Y, zeolite-L, zeolite-β, zeolite-Ω, mordenite, erionite, chabazite, and MFI zeolite.

[0021] The cracking catalyst may further include a carrier comprising carbon, clay, alkaline earth metal oxide, alkali metal oxide, alumina, silica, silica-alumina, zirconia, titania, silicon carbide, niobia, aluminum phosphate, alumina hydrate, or a mixture thereof.

[0022] Phosphorus (P) can be introduced into the above cracking catalyst.

[0023] Step b) above may use one or more fixed-bed reactors or circulating fluidized-bed reactors.

[0024] Step b) above is a reaction temperature of 300 to 900 ℃, 0.5 to 50 h -1 It can be performed at the space velocity of.

[0025] In one embodiment, the reactor of step b) above may be arranged such that the cracking catalyst is located at the top, the dehydrogenation catalyst is located in the middle, and the cracking catalyst is located at the bottom.

[0026] The reactor may comprise 1 to 50 parts by weight of the upper cracking catalyst, 1 to 79 parts by weight of the middle dehydrogenation catalyst, and 20 to 98 parts by weight of the lower cracking catalyst, based on 100 parts by weight of the total catalyst.

[0027] In another embodiment, the reactor of step b) above may be arranged such that the dehydrogenation catalyst is located at the top and the cracking catalyst is located at the bottom.

[0028] The reactor may contain 1 to 80 parts by weight of the upper dehydrogenation catalyst and 20 to 99 parts by weight of the lower cracking catalyst, based on 100 parts by weight of the total catalyst. Effects of the invention

[0030] The present invention enables the establishment of a process that is environmentally friendly and offers improved process economics by reducing greenhouse gas emissions, through the reaction of an oil-containing stream generated by the pyrolysis of waste plastic raw materials in the presence of a dehydrogenation catalyst and a cracking catalyst, thereby securing a higher yield of light olefins. Brief explanation of the drawing

[0032] FIG. 1 is a drawing showing an embodiment and a comparative example according to the present invention. Specific details for implementing the invention

[0033] The embodiments described in this specification may be modified in various different forms, and the technology according to one embodiment is not limited to the embodiments described below. Furthermore, the embodiments of one embodiment are provided to more fully explain the present disclosure to those with average knowledge in the relevant technical field. Unless otherwise defined, technical and scientific terms used herein have the meanings commonly understood by those with ordinary knowledge in the technical field to which this invention pertains, and descriptions of known functions and configurations that may unnecessarily obscure the essence of the present invention are omitted in the following description and accompanying drawings.

[0034] Additionally, the singular form used in this specification and the appended claims may be intended to include the plural form unless specifically indicated otherwise in the context.

[0035] Furthermore, in this specification and the appended claims, terms such as "first," "second," etc. are used not in a limiting sense, but for the purpose of distinguishing one component from another.

[0036] Furthermore, in this specification and the appended claims, when a part such as a film (layer), region, or component is described as being located "on," "on top," "on the upper," "under," "on the lower," or "on the lower" of another part, this includes not only cases where a part is in contact with another part, but also cases where another part exists between the two parts.

[0037] Furthermore, terms such as "approximately" and "substantially" as used in this specification and the appended claims are used to mean at or near the stated value when inherent manufacturing and material tolerances are presented in the said meaning, and are used to prevent unscrupulous infringers from unfairly exploiting the disclosure in which precise or absolute values ​​are mentioned to aid in understanding this specification and the appended claims.

[0038] Additionally, numeric ranges used in this specification include lower and upper limits and all values ​​within the range, increments logically derived from the shape and width of the defined range, all of which are limited values, and all possible combinations of upper and lower limits of numeric ranges limited in different forms.

[0039] Furthermore, terms such as "include" or "have" in this specification and the appended claims mean that the features or components described in the specification exist, and unless specifically limited, this does not preclude the possibility that one or more other features or components may be added.

[0040] Hereinafter, the method for producing light olefins from waste plastics through dehydrogenation and cracking reactions according to the present invention will be described in detail with reference to the attached drawings.

[0042] Light olefins refer to ethylene, propylene, and butene obtained from naphtha cracking, serving as essential basic raw materials for the petrochemical industry for the manufacture of various chemical products such as synthetic resins, synthetic rubber, and alcohols. While light olefins are primarily produced through the thermal cracking of petroleum-derived naphtha, this method involves high-temperature reactions exceeding 850°C, resulting in high energy consumption and the generation of large amounts of greenhouse gases. Therefore, there is a need for energy-efficient technologies that produce light olefins using sustainable materials, such as waste plastics.

[0043] Accordingly, methods for producing light olefins by reacting pyrolysis oil generated from the pyrolysis of waste plastics in the presence of a catalyst are being actively developed. Compared to conventional catalystless pyrolysis reactions, the catalytic decomposition reaction of waste plastic pyrolysis oil is a promising alternative that can overcome problems that may arise during the process of producing light olefins from waste plastic pyrolysis oil. Catalytic decomposition reactions have the advantage of being able to utilize waste plastic pyrolysis oil composed of a wide range of carbon numbers containing a large amount of olefins as a raw material, and enabling the production of light olefins with high yield while consuming relatively little energy. Zeolite-based catalysts, particularly ZSM-5, are known to be excellent as cracking catalysts for waste plastic pyrolysis oil. However, at low temperatures, paraffins composed of C9 or lower in waste plastic pyrolysis oil are not easily decomposed on the cracking catalyst, and even if decomposition occurs, there is a problem of low selectivity for light olefins.

[0044] Therefore, to selectively produce high-yield light olefins at low temperatures, a technology is required to first convert low-reactivity paraffins into relatively high-reactivity olefins through a dehydrogenation reaction and then crack them; this necessitates securing an optimal catalyst, catalyst arrangement, and optimal operating conditions (reaction temperature, space velocity, etc.).

[0046] The method for producing light olefins from waste plastics through dehydrogenation and cracking reactions according to the present invention comprises: a) a step of pyrolyzing waste plastic raw materials to produce an oil-containing stream; b) a step of reacting part or all of the oil-containing stream in the presence of a catalyst in one or more reactors; and c) a step of separating and recovering light olefins from the reaction products; wherein in step b), the catalyst comprises a dehydrogenation catalyst and a cracking catalyst.

[0047] The present invention enables the securing of a higher yield of light olefins by reacting an oil-containing stream generated by the pyrolysis of waste plastic raw materials in the presence of a dehydrogenation and cracking catalyst, and allows for the establishment of an eco-friendly process with improved process economics by reducing greenhouse gas emissions.

[0048] Step a) above is a step of pyrolyzing waste plastic raw materials, and is a step of converting waste plastic within a pyrolysis unit to produce an oil-containing stream containing hydrocarbon products.

[0049] The above waste plastic raw materials may include polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polystyrene (PS), etc., but are not limited thereto.

[0050] The above oil-containing stream is produced by pyrolyzing the waste plastic raw material, and may further mix biomass pyrolysis oil, recycled lubricating oil, high-chlorine content crude oil, Fischer-Tropsch process product, or a mixture thereof as needed.

[0051] In step a) above, the batch reactor may use a pyrolysis method using, for example, a rotary kiln type batch reactor, and the waste plastic may be uniformly melted before proceeding with pyrolysis, but is not limited thereto.

[0052] The above step a) may include, but is not limited to, a pretreatment step for purposes such as removing impurities and an additive injection step.

[0053] In one embodiment, step a) may further include the step of filtering the oil-containing stream through a filter.

[0054] In one embodiment, step a) may further include the step of contacting the oil-containing stream with any one of the adsorbents selected from activated carbon, ion exchange resin, silica gel, clay, zeolite, molecular sieve, activated aluminum oxide, and layered double hydroxide.

[0055] The above step a) further includes the step of contacting the oil-containing stream with an adsorbent selected from activated carbon, ion exchange resin, silica gel, clay, zeolite, molecular sieve, activated aluminum oxide, and layered double hydroxide, thereby removing solid components or substances that can be easily converted into coke contained in the oil-containing stream before being introduced into the reactor of step b) described later, thereby ensuring stable process operation and achieving the desired process yield.

[0056] Step a) above may be performed at a temperature of 700 ℃ or lower, 200 to 600 ℃, 350 to 500 ℃, or 400 to 500 ℃. Additionally, Step a) above may be performed at a pressure of 0 to 3 bar.g or 0 to 0.3 bar.g, but is not limited thereto.

[0057] Step a) above may involve pyrolysis for 30 minutes to 16 hours, preferably 3 hours to 10 hours, but is not limited thereto.

[0058] In one embodiment, the oil-containing stream may contain 1 to 80 weight%, 10 to 70 weight%, or 20 to 60 weight% of olefin.

[0059] In one embodiment, the oil-containing stream may contain 1 weight% or more, 2 weight% or more, 3 weight% or more, 4 weight% or more, or 5 weight% or more of aromatic hydrocarbons. The oil-containing stream may contain 50 weight% or less, 45 weight% or less, 40 weight% or less, 35 weight% or less, or 30 weight% or less of aromatic hydrocarbons. Additionally, the oil-containing stream may contain 1 to 50 weight%, 3 to 40 weight%, or 5 to 30 weight% of aromatic hydrocarbons.

[0060] In one embodiment, the oil-containing stream may contain hydrocarbons in the naphtha region composed of C5-C9 hydrocarbons in an amount of 1 wt% or more, 3 wt% or more, 5 wt% or more, 7 wt% or more, 8 wt% or more, 9 wt% or more, or 10 wt% or more. The oil-containing stream may contain naphtha containing C2-C12 hydrocarbons in an amount of 50 wt% or less, 45 wt% or less, or 40 wt% or less. Additionally, the oil-containing stream may contain hydrocarbons in the naphtha region composed of C5-C9 hydrocarbons in an amount of 1 to 50 wt%, 10 to 45 wt%, or 15 to 40 wt%.

[0061] In one embodiment, the oil-containing stream may simultaneously contain 20 to 60 weight% of olefins, 5 to 30 weight% of aromatic hydrocarbons, and 15 to 40 weight% of hydrocarbons in the naphtha region composed of C5-C9 hydrocarbons.

[0062] In one embodiment, the oil-containing stream may include one or more non-hydrocarbon materials selected from the group consisting of nitrogen component materials, sulfur component materials, oxygen component materials, and halogen component materials, but is not limited thereto.

[0063] In one embodiment, the oil-containing stream may contain 100 to 7000 ppm of nitrogen components.

[0064] In one embodiment, the oil-containing stream may contain 10 to 3000 ppm of sulfur.

[0065] In one embodiment, the oil-containing stream may contain 0.01 to 4 weight percent of an oxygen component.

[0066] In one embodiment, the oil-containing stream may contain 1 to 5000 ppm of halogen components.

[0067] In one embodiment, the oil-containing stream may simultaneously contain 100 to 7000 ppm of nitrogen, 10 to 3000 ppm of sulfur, 0.01 to 4 weight% of oxygen, and 1 to 5000 ppm of halogen.

[0068] Step b) above is a step of reacting the oil-containing stream with a catalyst to produce a light olefin in the presence of a dehydrogenation catalyst and a cracking catalyst.

[0069] In one embodiment, step b) may be performed in one or more fixed-bed reactors or circulating fluidized-bed reactors in the presence of a dehydrogenation catalyst and a cracking catalyst, but is not limited thereto.

[0070] The reaction in step b) above may be performed at 900 ℃ or lower, 800 ℃ or lower, 750 ℃ ​​or lower, 720 ℃ or lower, 700 ℃ or lower, or 680 ℃ or lower. The reaction in step b) above may be performed at 300 ℃ or higher, 400 ℃ or higher, 450 ℃ or higher, or 480 ℃ or higher. Additionally, the reaction in step b) above may be performed at 450 to 750 ℃, 470 to 700 ℃, or 480 to 680 ℃.

[0071] If the reaction temperature of step b) above is less than 500 ℃, the oil-containing stream produced by pyrolyzing the waste plastic raw material is not sufficiently converted into light olefin, and if it exceeds 700 ℃, the light olefin produced is converted into aromatic hydrocarbons due to the influence of excessive secondary reactions, which may result in a problem of reduced light olefin yield.

[0072] In step b) above, the space velocity (WHSV, Weight Hourly Space Velocity), defined as the ratio of the mass flow rate of the oil-containing stream to the mass of the dehydrogenation catalyst and the cracking catalyst, is 0.5 to 50 h -1 , 0.5 to 40 h -1 , 1 to 35 h -1 , 1 to 30 h -1 , 1 to 25 h -1 , 2 to 24 h -1 , or 3 to 12 h -1 It can be performed as.

[0073] The above space velocity is 12 h -1 In the case of excess, the oil-containing stream generated by the pyrolysis of the waste plastic raw material is not sufficiently converted into light olefin, and 3 h -1 If it is less than that, the light olefins produced are converted into aromatic hydrocarbons due to the influence of excessive secondary reactions, which may result in a problem of reduced light olefin yield.

[0074] The above dehydrogenation catalyst may use a composite catalyst in which an active metal is supported on a carrier.

[0075] The active metal of the above dehydrogenation catalyst may be Co, Cr, Pt, or a mixture thereof. Additionally, the active metal of the dehydrogenation may further include B, Ce, La, Zr, Zn, Sn, Re, Ga, or a mixture thereof, thereby improving the stability of the dehydrogenation catalyst and the light olefin yield.

[0076] As a support for the above dehydrogenation catalyst, alumina, silica, titina, zirconia, carbon, alkaline earth metal oxide, alkali metal oxide, silica-alumina, silicon carbide, niobia, aluminum phosphate, alumina hydrate, zeolite, clay, SAPO (silica-alumina-phosphate), ALPO (aluminum phosphate), MOF (Metal Organic Framework), amorphous silica-alumina, or a mixture thereof may be used. Preferably, spherical alumina (γ-Al2O3) particles with a particle size of 75-200 μm (Puralox 150, SASOL; BET surface area 200 m²) may be used. 2 and pore volume 0.45 cm 2 / g) may be, but is not limited to this.

[0077] In one embodiment, the content of the Co active metal supported on the carrier of the dehydrogenation catalyst may be 0.25, 0.5, 1, 2, 3, 5, 7, 10, or 15 wt%, preferably 1 to 10 wt%, but is not limited thereto.

[0078] In one embodiment, the content of the Cr active metal supported on the carrier in the dehydrogenation catalyst may be 3, 5, 10, 15, 20, or 30 wt%, preferably 10 to 20 wt%, but is not limited thereto.

[0079] In one embodiment, the content of the Pt active metal supported on the carrier of the dehydrogenation catalyst may be 0.01, 0.05, 0.1, 0.3, 0.5, 0.7, 1, or 2 wt%, preferably 0.2 to 1 wt%, but is not limited thereto.

[0080] As the cracking catalyst mentioned above, zeolite, clay, SAPO (silica-alumina-phosphate), ALPO (aluminum phosphate), MOF (Metal Organic Framework), amorphous silica-alumina, or a mixture thereof may be used. In addition, waste zeolite, waste clay, etc., can be utilized as is or after undergoing simple treatment to further improve activity. To use the waste zeolite, waste clay, etc., as a catalyst, air combustion may be carried out to remove coke, or solvent treatment may be performed to remove oil.

[0081] The zeolite of the cracking catalyst above may include one or more selected from the group consisting of ZSM-5, ZSM-11, ZSM-12, ZSM-22, ZSM-23, ZSM-48, zeolite X, zeolite Y, zeolite-L, zeolite-β, zeolite-Ω, mordenite, erionite, chabazite, and MFI zeolite.

[0082] The cracking catalyst may further include a carrier comprising carbon, clay, alkaline earth metal oxide, alkali metal oxide, alumina, silica, silica-alumina, zirconia, titania, silicon carbide, niobia, aluminum phosphate, alumina hydrate, or a mixture thereof.

[0083] In addition, the cracking catalyst may have phosphorus (P) introduced into it.

[0084] In one embodiment, the reactor of step b) may be arranged such that the cracking catalyst is located at the top, the dehydrogenation catalyst is located in the middle, and the cracking catalyst is located at the bottom, and may comprise 1 to 50 parts by weight of the cracking catalyst at the top, 1 to 80 parts by weight of the dehydrogenation catalyst at the middle, and 20 to 99 parts by weight of the cracking catalyst at the bottom, based on 100 parts by weight of the total catalyst, but is not limited thereto.

[0085] In one embodiment, the reactor of step b) may be arranged such that the dehydrogenation catalyst is located at the top and the cracking catalyst is located at the bottom, and may include 1 to 79 parts by weight of the dehydrogenation catalyst at the top and 20 to 98 parts by weight of the cracking catalyst at the bottom, based on 100 parts by weight of the total catalyst, but is not limited thereto.

[0086] Step c) above is a step of separating and recovering light olefins produced by the reaction of step b), and the light olefins may include ethylene, propylene, or C4 olefins.

[0087] In one embodiment, the light olefin yield may be 20 wt% or more, 25 wt% or more, 30 wt% or more, or 35 wt% or more. The light olefin yield may be 70 wt% or less, 60 wt% or less, 55 wt%, or 50 wt% or less. Additionally, the light olefin yield may be 30 to 70 wt%, 35 to 60 wt%, or 35 to 50 wt%.

[0089] Experimental examples are described below with specific examples. However, the experimental examples described below are merely illustrative of some aspects, and the technology described in this specification is not limited thereto.

[0091] <Preparation Example 1> Cracking catalyst

[0092] Solution 1 was prepared by adding 29.51 g of distilled water to 36.83 g of water glass and stirring for 30 minutes. Additionally, Solution 2 was prepared by mixing 3.95 g of aluminum sulfate, 0.19 g of sulfuric acid, and 29.51 g of distilled water and stirring for 20 minutes. Solution 2 was added to Solution 1 and stirred, then placed in a Teflon container and hydrothermally synthesized at 170 °C for 24 hours, followed by cooling at room temperature. Subsequently, 50 g of a 10 wt% ammonium sulfate solution was mixed with 4 g of ZSM-5 precursor recovered through filtration and washing processes and stirred for 30 minutes. Then, ZSM-5 was synthesized by performing washing and filtration three consecutive times and ion exchange.

[0093] 165.25 g of the synthesized ZSM-5 (Si / Al = 11) was slowly added to 321.23 g of distilled water while stirring, and then 71.47 g of 85% phosphoric acid was added and stirred at room temperature for 30 minutes to prepare a slurry. To the slurry, a solution of 277.54 g of boehmite (Al2O3 content 72 wt%) dispersed in a 2% nitric acid solution was added and stirred for 1 hour, after which 166.5 g of clay was added and thoroughly mixed for 2 hours using a high-viscosity slurry mixer. This was spray-molded to obtain microspheres with a particle size of 75-200 μm, and calcined at 650 ℃ for 5 hours. After loading the above-mentioned calcined microspheres into a steam treatment reactor, distilled water was injected at a rate of 5 cc / min using a liquid pump to vaporize them, and the pre-steamed P / ZSM-5 cracking catalyst was obtained by contacting the sample in the form of steam at 760 ℃ for 24 hours in a 100% steam atmosphere.

[0095] <Preparation Example 2> Co-containing dehydrogenation catalyst

[0096] Boric acid (H3BO3) was injected into methanol and stirred for 3 hours to prepare a boron oxide solution. The boron oxide solution was then mixed with spherical alumina (γ-Al2O3) particles (Puralox 150, SASOL; BET surface area 200m²) having a particle size of 75–200 μm. 2 and pore volume 0.45 cm 2 A boron oxide-alumina carrier was prepared by adding to ( / g) and impregnating using the incipient wetness impregnation method, heating at a rate of 2 ℃ per minute, and then calcining at a calcination temperature of 500 ℃ for 6 hours. The boric acid contained 1 wt% boron (B) relative to the alumina, and the methanol was prepared in an amount equal to the pore volume of the alumina.

[0097] A cobalt-platinum oxide solution was prepared by dissolving Co(NO3)2·6H2O (cobalt nitrate hexahydrate) containing 6 wt% cobalt relative to the alumina and H2PtCl6·6H2O (chloroplatinic acid) containing 100 ppm (0.01 wt%) platinum in water prepared in an amount equal to the pore volume of the alumina and co-impregnating. The prepared cobalt-platinum oxide solution was added to the prepared boron oxide-alumina carrier and impregnated using an initial wet impregnation method. After drying at 100°C for 12 hours, the temperature was increased at a rate of 1°C per minute, and then calcined at a calcination temperature of 800°C for 6 hours to prepare a cobalt-platinum / boron oxide-alumina dehydrogenation catalyst.

[0099] <Preparation Example 3> Cr-containing dehydrogenation catalyst

[0100] A chromium oxide aqueous solution was prepared by injecting CrO3 into distilled water and stirring for 3 hours. The above chromium oxide aqueous solution was then applied to spherical alumina (γ-Al2O3) particles (Puralox 150, SASOL; BET surface area 200m²) with a particle size of 75–200 μm. 2 and pore volume 0.45 cm2 It was impregnated using an initial wet impregnation method by adding it to ( / g). Afterward, it was aged at 25°C for 3 hours, dried at 100°C for 12 hours, and calcined in air at 850°C for 10 hours to prepare a chromium oxide dehydrogenation catalyst supported on γ-alumina. The chromium oxide was 15 wt% relative to the alumina.

[0102] <Preparation Example 4> Pt-containing dehydrogenation catalyst

[0103] SnCl2·2H2O was injected into a 6% nitric acid aqueous solution and stirred for 3 hours, then spherical alumina (γ-Al2O3) particles with a particle size of 75–200 µm (Puralox 150, SASOL; BET surface area 200 m² 2 and pore volume 0.45 cm 2 It was impregnated using the initial wet impregnation method by adding ( / g). Subsequently, the alumina containing Sn was dried at 100 °C for 12 hours and calcined in air at 550 °C for 5 hours. The catalyst thus prepared was impregnated using the initial wet impregnation method with an aqueous solution prepared by injecting H2PtCl6·6H2O into distilled water. Subsequently, the alumina catalyst containing Sn and Pt was dried at 100 °C for 12 hours and calcined in air at 550 °C for 5 hours to prepare a Pt-Sn dehydrogenation catalyst supported on γ-alumina. The Sn was 1.3 wt% relative to the alumina, and the Pt was 0.35 wt% relative to the alumina.

[0105] <Example 1>

[0106] a) Waste mixed plastics (PE, PP, and PS) were fed into a rotary kiln reactor and pyrolyzed in an oxygen-free atmosphere to produce an oil-containing stream. Fuel was supplied to the bottom of the rotating reactor and combusted to heat the internal temperature of the reactor to 350 to 500 °C. At this time, the gas emitted from the pyrolysis was condensed to a density of 0.812 g / cm³ 3And, at 23.6 ℃, an oil-containing stream with a viscosity of 4.0 cP was produced.

[0107] b) The above oil-containing stream was fed into a fixed-bed reactor loaded with 3 g of dehydrogenation catalyst at the top and 3 g of cracking catalyst at the bottom, and the catalytic reaction was carried out. (Feed rate 0.8 g / min, reaction temperature 540 ℃, space velocity (WHSV) 8 h -1 At this time, the dehydrogenation catalyst used was the catalyst prepared in Preparation Example 2 above, and the cracking catalyst used was the catalyst prepared in Preparation Example 1.

[0108] c) The light olefins were separated and recovered from the above reaction product through a conventional fractional distillation method. The recovered ethylene yield, propylene yield, C4 olefin yield, and light olefin yield were calculated based on 100% by weight of the input oil-containing stream.

[0110] <Example 2>

[0111] b) The process was carried out in the same manner as in Example 1, except that in step b), 1.5 g of cracking catalyst was loaded at the top of the reactor, 3 g of dehydrogenation catalyst was loaded in the middle of the reactor, and 1.5 g of cracking catalyst was loaded at the bottom of the reactor. At this time, the dehydrogenation catalyst was the catalyst prepared in Preparation Example 2, and the cracking catalyst was the catalyst prepared in Preparation Example 1.

[0113] <Example 3>

[0114] The procedure was carried out in the same manner as Example 2, except that the catalyst prepared in Preparation Example 3 above was used as the dehydrogenation catalyst.

[0116] <Example 4>

[0117] The procedure was carried out in the same manner as Example 2, except that the catalyst prepared in Preparation Example 4 above was used as the dehydrogenation catalyst.

[0119] <Example 5>

[0120] b) The process was carried out in the same manner as Example 1, except that a catalyst layer was not formed in the reactor (no catalyst) in step b).

[0122] <Example 6>

[0123] b) The process was carried out in the same manner as Example 1, except that the catalytic reaction was carried out in a reactor loaded with 3 g of cracking catalyst.

[0125] <Comparative Example 1>

[0126] b) The process was carried out in the same manner as in Example 1, except that 3 g of cracking catalyst and 3 g of dehydrogenation catalyst were loaded at the top of the reactor and at the bottom of the reactor, respectively. At this time, the dehydrogenation catalyst was the catalyst prepared in Preparation Example 2, and the cracking catalyst was the catalyst prepared in Preparation Example 1.

[0128] <Comparative Example 2>

[0129] b) The process was carried out in the same manner as in Example 1, except that the catalytic reaction was carried out in a reactor loaded with a catalyst in which 3 g of the cracking catalyst and 3 g of the dehydrogenation catalyst were physically and uniformly mixed. At this time, the dehydrogenation catalyst was the catalyst prepared in Preparation Example 2, and the cracking catalyst was the catalyst prepared in Preparation Example 1.

[0131] [Table 1] shows the results of Examples 1 to 6, Comparative Example 1, and Comparative Example 2.

[0133] catalyst Ethylene yield (wt%) Propylene yield (wt%) C4 Olefin Yield (wt%) BTXs Yield (wt%) Light olefin yield (wt%) Example 1 Dehydrogenation / Cracking 6.23 16.89 12.81 13.34 35.93 Example 2 Cracking / Dehydrogenation / Cracking 5.82 20.09 17.18 12.95 43.09 Example 3 Cracking / Dehydrogenation / Cracking 5.47 17.52 15.37 14.18 38.36 Example 4 Cracking / Dehydrogenation / Cracking 4.78 19.76 17.33 10.71 41.87 Example 5 Non-catalytic decomposition (pyrolysis) 0.87 1.36 0.99 8.15 3.22 Example 6 Cracking alone 3.34 15.57 14.24 9.68 33.15 Comparative Example 1 Cracking / Dehydrogenation 6.23 10.06 6.01 14.59 22.30 Comparative Example 2 Cracking + Dehydrogenation 10.87 11.15 4.64 17.82 26.66

[0135] The light olefin yield of Example 1 was measured at 35.93 wt%, which is an increase compared to the light olefin yield of Example 6 at 33.15 wt%.

[0136] The light olefin yield of Example 2 was measured at 43.09 wt%, the light olefin yield of Example 3 at 38.36 wt%, and the light olefin yield of Example 4 at 41.87 wt%, which is an increase compared to the light olefin yields of Examples 1 and 6.

[0137] In addition, the light olefin yield of Comparative Example 1 was measured at 23.30 wt%, and the light olefin yield of Comparative Example 2 was measured at 26.66 wt%, which is a decrease compared to the light olefin yield of Example 6.

[0139] As described above, the present invention has been explained in this specification by specific details and limited embodiments, but this is provided only to aid in a more comprehensive understanding of the invention, and the invention is not limited to the above embodiments. A person skilled in the art to which the invention pertains can make various modifications and variations from this description. Accordingly, the concept described in this specification should not be limited to the described embodiments, and all things equivalent to or having equivalent variations to the claims set forth below, as well as the claims themselves, shall be considered to fall within the scope of the concept described in this specification.

Claims

Claim 1 a) a step of pyrolyzing waste plastic raw materials to produce an oil-containing stream; b) a step of reacting part or all of the oil-containing stream in the presence of a catalyst in one or more reactors; and c) a step of separating and recovering a light olefin from the reaction product of step b); wherein the reactor of step b) is arranged such that a cracking catalyst is positioned at the top, a dehydrogenation catalyst in the middle, and a cracking catalyst at the bottom. A method for producing a light olefin from waste plastic. Claim 2 A method for producing light olefin from waste plastic according to claim 1, wherein the oil-containing stream comprises 1 to 80 weight% olefin, 1 to 50 weight% aromatic hydrocarbon, and 1 to 50 weight% naphtha hydrocarbon composed of C5-C9 hydrocarbons. Claim 3 A method for producing light olefins from waste plastics according to claim 1, wherein the oil-containing stream comprises one or more non-hydrocarbon materials selected from the group consisting of nitrogen component materials, sulfur component materials, oxygen component materials, and halogen component materials. Claim 4 A method for producing light olefins from waste plastics, wherein the oil-containing stream comprises 100 to 7000 ppm of nitrogen, 10 to 3000 ppm of sulfur, 0.01 to 4 weight% of oxygen, and 1 to 5000 ppm of halogen. Claim 5 A method for producing light olefins from waste plastics, wherein the dehydrogenation catalyst is a composite catalyst in which an active metal is supported on a carrier. Claim 6 A method for producing light olefins from waste plastics, wherein the active metal of the dehydrogenation catalyst is Co, Cr, Pt, or a mixture thereof, in claim 5. Claim 7 A method for producing light olefins from waste plastics according to claim 6, wherein the active metal for dehydrogenation further comprises B, Ce, La, Zr, Zn, Sn, Re, Ga, or a mixture thereof. Claim 8 A method for producing light olefins from waste plastics, wherein the carrier of the dehydrogenation catalyst is alumina, silica, titina, zirconia, carbon, alkaline earth metal oxide, alkali metal oxide, silica-alumina, silicon carbide, niobia, aluminum phosphate, alumina hydrate, zeolite, clay, SAPO (silica-alumina-phosphate), ALPO (aluminum phosphate), MOF (Metal Organic Framework), amorphous silica-alumina, or a mixture thereof. Claim 9 A method for producing light olefins from waste plastics, wherein the cracking catalyst in claim 1 is zeolite, clay, SAPO (silica-alumina-phosphate), ALPO (aluminum phosphate), MOF (Metal Organic Framework), amorphous silica-alumina, or a mixture thereof. Claim 10 A method for producing light olefins from waste plastics according to claim 9, wherein the zeolite of the cracking catalyst comprises one or more selected from the group consisting of ZSM-5, ZSM-11, ZSM-12, ZSM-22, ZSM-23, ZSM-48, zeolite X, zeolite Y, zeolite-L, zeolite-β, zeolite-Ω, mordenite, erionite, chabazite, and MFI zeolite. Claim 11 A method for producing light olefins from waste plastics, wherein the cracking catalyst further comprises a carrier comprising carbon, clay, alkaline earth metal oxide, alkali metal oxide, alumina, silica, silica-alumina, zirconia, titania, silicon carbide, niobia, aluminum phosphate, alumina hydrate, or a mixture thereof. Claim 12 In claim 9, the cracking catalyst is a method for producing light olefins from waste plastics into which phosphorus (P) has been introduced. Claim 13 In claim 1, the above step b) is a method for producing light olefins from waste plastics using one or more fixed-bed reactors or circulating fluidized-bed reactors. Claim 14 In claim 1, the above step b) is a reaction temperature of 300 to 900 ℃ and 0.5 to 50 h -1 A method for producing light olefins from waste plastics performed at a space velocity. Claim 15 delete Claim 16 A method for producing light olefin from waste plastic according to claim 1, wherein the reactor comprises 1 to 50 parts by weight of the upper cracking catalyst, 1 to 79 parts by weight of the middle dehydrogenation catalyst, and 20 to 98 parts by weight of the lower cracking catalyst, based on 100 parts by weight of the total catalyst. Claim 17 delete Claim 18 delete

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