Method for producing light olefins from waste plastics via dehydrogenation and cracking reactions

Abstract

The present invention relates to a method for producing light olefins from waste plastics, the method comprising the steps of: a) pyrolyzing a waste plastic feedstock to generate 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

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

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

[0002]

[0003] Light olefins, such as ethylene, propylene, and butene, are obtained through naphtha cracking. They are essential raw materials for the petrochemical industry, essential for the production of various chemical products such as synthetic resins, synthetic rubber, and alcohol. Light olefins are primarily produced through the thermal cracking of petroleum-derived naphtha. However, this process consumes significant energy due to the high-temperature reaction temperature of over 850°C and generates large amounts of greenhouse gases. Therefore, energy-efficient technologies that utilize sustainable materials, such as waste plastics, to produce light olefins are needed.

[0004] Meanwhile, polyolefin plastics, such as polyethylene and polypropylene, widely used as packaging materials, account for more than 60% of global plastic waste due to their short product lifespans. Mechanical recycling of these waste plastics is difficult to widely apply due to impurities derived from other plastics, additives, and fillers. Furthermore, disposal methods such as landfilling and incineration are unsuitable due to their high environmental pollution potential. Therefore, to mitigate the negative environmental impacts of existing waste plastic disposal methods and facilitate a transition to a circular economy with lower carbon emissions, the development of new, energy-efficient processes for converting waste plastics into valuable light olefins is essential.

[0005] Accordingly, methods for producing light olefins by reacting pyrolysis oil produced by pyrolysis of waste plastics in the presence of a catalyst are being actively developed. Compared to conventional non-catalytic pyrolysis reactions, catalytic cracking 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 cracking reactions can utilize waste plastic pyrolysis oil composed of a wide range of carbon atoms and containing a large amount of olefins as a raw material, and have the advantages of consuming relatively little energy and producing high yields of light olefins. Zeolite-based catalysts, especially ZSM-5, are known to be excellent cracking catalysts for waste plastic pyrolysis oil. However, paraffins composed of C9 or less in waste plastic pyrolysis oil are not easily cracked on cracking catalysts at low temperatures, and even when cracked, the selectivity for light olefins is low.

[0006] Therefore, in order to selectively produce high yields of light olefins at low temperatures, a technology is needed to first convert low-reactivity paraffins into relatively highly reactive olefins through dehydrogenation and then crack them. To this end, it is necessary to secure optimal catalysts, catalyst arrangements, and optimal operating conditions (reaction temperature, space velocity, etc.).

[0007]

[0008] The present invention provides a method for producing light olefins from waste plastics in the presence of a dehydrogenation catalyst and a cracking catalyst.

[0009]

[0010] The method for producing light olefins from waste plastics through dehydrogenation and cracking reactions of the present invention comprises the steps of: a) pyrolyzing waste plastic raw materials to produce an oil-containing stream; b) reacting part or all of the oil-containing stream in the presence of a catalyst in one or more reactors; and c) separating and recovering light olefins from the reaction product; wherein the catalyst in step b) may include a dehydrogenation catalyst and a cracking catalyst.

[0011] The oil-containing stream may comprise 1 to 80 wt% olefins, 1 to 50 wt% aromatic hydrocarbons, and 1 to 50 wt% naphtha hydrocarbons composed of C5-C9 hydrocarbons.

[0012] The above oil-containing stream may include one or more non-hydrocarbon substances selected from the group consisting of nitrogen-containing substances, sulfur-containing substances, oxygen-containing substances, and halogen-containing substances.

[0013] The above oil-containing stream may contain 100 to 7000 ppm of nitrogen components, 10 to 3000 ppm of sulfur components, 0.01 to 4 wt% of oxygen components, and 1 to 5000 ppm of halogen components.

[0014] The above dehydrogenation catalyst may be a composite catalyst in which an active metal is supported on a carrier.

[0015] The active metal of the above dehydrogenation catalyst may be Co, Cr, Pt or a mixture thereof.

[0016] The active metal for the above dehydrogenation may further include B, Ce, La, Zr, Zn, Sn, Re, Ga or a mixture thereof.

[0017] The carrier of the above dehydrogenation catalyst may be alumina, silica, titanate, 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.

[0018] 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.

[0019] The zeolite of the above cracking catalyst may include at least one 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.

[0020] The cracking catalyst may further comprise 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.

[0021] The above cracking catalyst may have phosphorus (P) introduced into it.

[0022] Step b) above may use one or more fixed bed reactors or circulating fluidized bed reactors.

[0023] The above step b) is carried out at a reaction temperature of 300 to 900 ℃ for 0.5 to 50 h. -1 can be performed at the spatial velocity of .

[0024] 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 at the bottom, and the cracking catalyst is located at the bottom.

[0025] The above reactor may contain 1 to 50 parts by weight of the cracking catalyst at the top, 1 to 79 parts by weight of the dehydrogenation catalyst at the middle, and 20 to 98 parts by weight of the cracking catalyst at the bottom, based on 100 parts by weight of the total catalyst.

[0026] In another embodiment, the reactor of step b) may be arranged such that the dehydrogenation catalyst is positioned at the top and the cracking catalyst is positioned at the bottom.

[0027] The above reactor may include 1 to 80 parts by weight of the dehydrogenation catalyst at the top and 20 to 99 parts by weight of the cracking catalyst at the bottom, based on 100 parts by weight of the total catalyst.

[0028]

[0029] The present invention enables the production of an oil-containing stream produced by thermally decomposing waste plastic raw materials and reacting the stream in the presence of a dehydrogenation catalyst and a cracking catalyst, thereby securing a higher yield of light olefins and reducing greenhouse gas emissions, thereby enabling the construction of an environmentally friendly process with improved process economics.

[0030]

[0031] Figure 1 is a drawing showing an embodiment and a comparative example according to the present invention.

[0032]

[0033] The embodiments described herein may be modified in various different forms, and the technology according to one embodiment is not limited to the embodiments described below. In addition, the embodiments of one embodiment are provided to more completely explain the present disclosure to a person with average knowledge in the relevant technical field. In this case, unless there is a different definition for the technical and scientific terms used, they have the meaning commonly understood by a person with ordinary skill in the technical field to which this invention belongs, and in the following description and the attached drawings, descriptions of well-known functions and configurations that may unnecessarily obscure the gist of the present invention are omitted.

[0034] Additionally, the singular forms used in this specification and the appended claims are intended to include the plural forms as well, unless the context clearly dictates otherwise.

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

[0036] Additionally, in this specification and the appended claims, when a part such as a film (layer), region or component is said to be located “on,” “above,” “upper,” “below,” “lower,” or “lower” another part, this includes not only cases where one part is in contact with another part, but also cases where another part exists between the two parts.

[0037] In addition, the terms "about," "substantially," and the like used in this specification and the appended claims are used in a meaning that is at or close to the numerical value when manufacturing and material tolerances inherent in the meanings stated are presented, and are used to prevent unscrupulous infringers from unfairly utilizing the disclosure in which exact or absolute values ​​are stated to aid in the understanding of this specification and the appended claims.

[0038] Additionally, the numerical ranges used herein include lower and upper limits and all values ​​within that range, increments logically derived from the shape and width of the defined range, all doubly defined values, and all possible combinations of upper and lower limits of numerical ranges defined in different shapes.

[0039] Furthermore, terms such as “include” or “have” in this specification and the appended claims mean that a feature or component described in the specification is present, and unless specifically limited, do not preclude the possibility that one or more other features or components may be added.

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

[0041]

[0042] Light olefins, such as ethylene, propylene, and butene, are obtained through naphtha cracking. They are essential raw materials for the petrochemical industry, essential for the production of various chemical products such as synthetic resins, synthetic rubber, and alcohol. Light olefins are primarily produced through the thermal cracking of petroleum-derived naphtha. However, this process consumes significant energy due to the high-temperature reaction temperature of over 850°C and generates large amounts of greenhouse gases. Therefore, energy-efficient technologies that utilize sustainable materials, such as waste plastics, to produce light olefins are needed.

[0043] Accordingly, methods for producing light olefins by reacting pyrolysis oil produced by pyrolysis of waste plastics in the presence of a catalyst are being actively developed. Compared to conventional non-catalytic pyrolysis reactions, catalytic cracking 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 cracking reactions can utilize waste plastic pyrolysis oil composed of a wide range of carbon atoms and containing a large amount of olefins as a raw material, and have the advantages of consuming relatively little energy and producing high yields of light olefins. Zeolite-based catalysts, especially ZSM-5, are known to be excellent cracking catalysts for waste plastic pyrolysis oil. However, paraffins composed of C9 or less in waste plastic pyrolysis oil are not easily cracked on cracking catalysts at low temperatures, and even when cracked, the selectivity for light olefins is low.

[0044] Therefore, in order to selectively produce high yields of light olefins at low temperatures, a technology is needed to first convert low-reactivity paraffins into relatively highly reactive olefins through dehydrogenation and then crack them. To this end, it is necessary to secure optimal catalysts, catalyst arrangements, and optimal operating conditions (reaction temperature, space velocity, etc.).

[0045]

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

[0047] The present invention enables the construction of a process that is environmentally friendly and has improved process economics by reducing greenhouse gas emissions and securing a higher yield of light olefins by reacting an oil-containing stream produced by thermal decomposition of waste plastic raw materials in the presence of a dehydrogenation and cracking catalyst.

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

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

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

[0051] The above step a) may use a pyrolysis method using a batch reactor, for example, a rotary kiln type batch reactor, and pyrolysis may be performed after uniformly melting waste plastic, but is not limited thereto.

[0052] The above step a) may include, but is not limited to, a pretreatment step and an additive injection step for the purpose of removing impurities, etc.

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

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

[0055] The step a) above further includes a step of contacting the oil-containing stream with any one 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 to coke contained in the oil-containing stream before being fed into the reactor of step b) described below, thereby promoting stable process operation and achieving the desired process yield.

[0056] The above step a) may be performed at a temperature of 700°C or less, 200 to 600°C, 350 to 500°C, or 400 to 500°C. In addition, the above step a) 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] The above step a) may be thermal decomposition 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 comprise 1 to 80 wt%, 10 to 70 wt%, or 20 to 60 wt% olefin.

[0059] In one embodiment, the oil-containing stream can comprise at least 1 wt%, at least 2 wt%, at least 3 wt%, at least 4 wt%, or at least 5 wt% of aromatic hydrocarbons. The oil-containing stream can comprise up to 50 wt%, up to 45 wt%, up to 40 wt%, up to 35 wt%, or up to 30 wt% of aromatic hydrocarbons. Additionally, the oil-containing stream can comprise from 1 to 50 wt%, from 3 to 40 wt%, or from 5 to 30 wt% of aromatic hydrocarbons.

[0060] In one embodiment, the oil-containing stream can comprise at least 1 wt%, at least 3 wt%, at least 5 wt%, at least 7 wt%, at least 8 wt%, at least 9 wt%, or at least 10 wt% of hydrocarbons in the naphtha region composed of C5-C9 hydrocarbons. The oil-containing stream can comprise at most 50 wt%, at most 45 wt%, or at most 40 wt% of naphtha containing C2-C12 hydrocarbons. Additionally, the oil-containing stream can comprise from 1 to 50 wt%, from 10 to 45 wt%, or from 15 to 40 wt% of hydrocarbons in the naphtha region composed of C5-C9 hydrocarbons.

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

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

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

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

[0065] In one embodiment, the oil-containing stream may comprise 0.01 to 4 wt% of an oxygen component.

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

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

[0068] The above step b) is a step of reacting the oil-containing stream with a catalyst, and is a step of producing light olefins in the presence of a dehydrogenation catalyst and a cracking catalyst.

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

[0070] The reaction of step b) may be performed at 900°C or less, 800°C or less, 750°C or less, 720°C or less, 700°C or less, or 680°C or less. The reaction of step b) may be performed at 300°C or more, 400°C or more, 450°C or more, or 480°C or more. In addition, the reaction of step b) may be performed at 450 to 750°C, 470 to 700°C, or 480 to 680°C.

[0071] If the reaction temperature of step b) is less than 500°C, the oil-containing stream produced by thermal decomposition of the waste plastic raw material is not sufficiently converted into light olefin, and if it exceeds 700°C, the light olefin produced may be converted into aromatic hydrocarbon due to the influence of excessive secondary reaction, which may cause a problem in that the yield of light olefin is reduced.

[0072] The weight hourly space velocity (WHSV), defined as the ratio of the mass flow rate of the oil-containing stream to the mass of the dehydrogenation catalyst and cracking catalyst in step b), 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 can be performed.

[0073] The above space velocity is 12 h -1 If it exceeds, the oil-containing stream produced by pyrolyzing the waste plastic raw material is not sufficiently converted into light olefin, and 3 h -1 If it is less than this, the light olefins produced due to the influence of excessive secondary reactions may be converted into aromatic hydrocarbons, which may cause a problem in that the yield of light olefins decreases.

[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. In addition, 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 yield of light olefins.

[0076] As a carrier of the above dehydrogenation catalyst, alumina, silica, titania, 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 can be used. Preferably, spherical alumina (γ-Al2O3) particles (Puralox 150, SASOL; BET surface area 200 m) having a particle size of 75-200 μm are used. 2 and pore volume 0.45cm 2 / g) but is not limited to this.

[0077] In one embodiment, the dehydrogenation catalyst may have a content of the Co active metal supported on the carrier of 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 dehydrogenation catalyst may have a content of the Cr active metal supported on the carrier of 3, 5, 10, 15, 20 or 30 wt%, preferably 10 to 20 wt%, but is not limited thereto.

[0079] In one embodiment, the dehydrogenation catalyst may have a content of the Pt active metal supported on the carrier of 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] The cracking catalysts mentioned above may include zeolite, clay, SAPO (silica-alumina-phosphate), ALPO (aluminum phosphate), MOF (Metal Organic Framework), amorphous silica-alumina, or mixtures thereof. Furthermore, waste zeolite, waste clay, etc. may be utilized as is or after simple treatment to further enhance activity. In order to utilize the waste zeolite, waste clay, etc. as a catalyst, air combustion may be performed to remove coke, or solvent treatment may be performed to remove oil.

[0081] The zeolite of the above cracking catalyst may include at least one 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 comprise 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] Additionally, the cracking catalyst may have phosphorus (P) introduced therein.

[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 at the middle, and the cracking catalyst is located at the bottom, and may include 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 so that the dehydrogenation catalyst is positioned at the top and the cracking catalyst is positioned 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] The above step c) is a step of separating and recovering light olefin produced by the reaction of the above step b), and the light olefin may include ethylene, propylene or C4 olefin.

[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 less, 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%.

[0088]

[0089] Hereinafter, specific examples of experiments will be provided and explained. However, the experimental examples described below are only illustrative, and the technology described in this specification is not limited thereto.

[0090]

[0091] <Manufacturing 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. In addition, 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, stirred, placed in a Teflon container, and hydrothermally synthesized at 170 °C for 24 hours, and then cooled to room temperature. Afterwards, 50 g of a 10 wt% ammonium sulfate solution was mixed with 4 g of the ZSM-5 precursor recovered through the filtration and washing processes, stirred for 30 minutes, and then the washing and filtration processes were performed three times in succession and ion exchange was performed to synthesize ZSM-5.

[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 additionally added and stirred at room temperature for 30 minutes to prepare a slurry. A solution of 277.54 g of boehmite (Al2O3 content 72 wt%) dispersed in a 2% nitric acid solution was additionally added to the slurry, stirred for 1 hour, and then 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 ㎛, and calcined at 650 °C for 5 hours. After the above-mentioned calcined microspheres were loaded 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°C for 24 hours in a 100% steam atmosphere.

[0094]

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

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

[0097] Co(NO3)2·6H2O (cobalt nitrate hexahydrate) containing 6 wt% of cobalt compared to the above alumina and H2PtCl6·6H2O (chloroplatinic acid) containing 100 ppm (0.01 wt%) of platinum were dissolved in water prepared in an amount equal to the pore volume of the above alumina and co-impregnated to prepare a cobalt-platinum oxide solution. The above-prepared cobalt-platinum oxide solution was added to the above-prepared boron oxide-alumina support and impregnated using the initial wetness impregnation method, dried at 100°C for 12 hours, heated at a heating 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.

[0098]

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

[0100] CrO3 was injected into distilled water and stirred for 3 hours to prepare a chromium oxide aqueous solution. The chromium oxide aqueous solution was mixed with spherical alumina (γ-Al2O3) particles (Puralox 150, SASOL; BET surface area 200 m) having a particle size of 75 to 200 μm.2 and pore volume 0.45cm 2 / g) was added and impregnated using the initial wetness impregnation method. After that, 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.

[0101]

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

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

[0104]

[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 reactor to an internal temperature of 350 to 500°C. At this time, the gas discharged through pyrolysis was condensed to a density of 0.812 g / cm. 3 , and an oil-containing stream having a viscosity of 4.0 cP at 23.6 ℃ was produced.

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

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

[0109]

[0110] <Example 2>

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

[0112]

[0113] <Example 3>

[0114] The same procedure as Example 2 was followed, except that the catalyst manufactured in Manufacturing Example 3 was used as the dehydrogenation catalyst.

[0115]

[0116] <Example 4>

[0117] The same procedure as Example 2 was followed, except that the catalyst manufactured in Manufacturing Example 4 was used as the dehydrogenation catalyst.

[0118]

[0119] <Example 5>

[0120] b) The process was carried out in the same manner as Example 1, except that no catalyst layer was formed in the reactor in step b).

[0121]

[0122] <Example 6>

[0123] 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 3 g of a cracking catalyst.

[0124]

[0125] <Comparative Example 1>

[0126] b) The catalytic reaction was carried out in the same manner as in Example 1, except that 3 g of a cracking catalyst was loaded at the top of the reactor and 3 g of a dehydrogenation catalyst was loaded at the bottom of the reactor. At this time, the dehydrogenation catalyst used was the catalyst manufactured in Manufacturing Example 2, and the cracking catalyst used was the catalyst manufactured in Manufacturing Example 1.

[0127]

[0128] Comparative Example 2

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

[0130]

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

[0132]

[0133] Catalytic Ethylene Yield (wt%)Propylene Yield (wt%)C4 Olefin Yield (wt%)BTXs Yield (wt%)Light Olefin Yield (wt%)Example 1Dehydrogenation / Cracking6.2316.8912.8113.3435.93Example 2Cracking / Dehydrogenation / Cracking5.8220.0917.1812.9543.09Example 3Cracking / Dehydrogenation / Cracking5.4717.5215.3714.1838.36Example 4Cracking / Dehydrogenation / Cracking4.7819.7617.3310.7141.87Example 5Non-catalytic cracking (thermal cracking)0.871.360.998.153.22Example 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

[0134]

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

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

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

[0138]

[0139] Although the present invention has been described in this specification with specific details and limited examples, these are provided only to help a more general understanding of the present invention, and the present invention is not limited to the above examples, and those skilled in the art to which the present invention pertains can make various modifications and variations based on these descriptions. Therefore, the ideas described in this specification should not be limited to the described examples, and all things that are equivalent or equivalent to the claims below, as well as the claims, are considered to fall within the scope of the ideas described in this specification.

Claims

1. a) A step of thermally decomposing waste plastic raw materials to generate an oil-containing stream; b) reacting part or all of said oil-containing stream in the presence of a catalyst in one or more reactors; and c) a step of separating and recovering light olefin from the reaction product; A method for producing light olefins from waste plastic, wherein the catalyst in step b) includes a dehydrogenation catalyst and a cracking catalyst.

2. In paragraph 1, A method for producing light olefins from waste plastics, wherein the oil-containing stream comprises 1 to 80 wt% of olefins, 1 to 50 wt% of aromatic hydrocarbons and 1 to 50 wt% of hydrocarbons in the naphtha region consisting of C5-C9 hydrocarbons.

3. In paragraph 1, A method for producing light olefins from waste plastics, wherein the oil-containing stream comprises at least one non-hydrocarbon material selected from the group consisting of nitrogen-component materials, sulfur-component materials, oxygen-component materials, and halogen-component materials.

4. In paragraph 3, A method for producing light olefins from waste plastics, wherein the oil-containing stream contains 100 to 7000 ppm of nitrogen components, 10 to 3000 ppm of sulfur components, 0.01 to 4 wt% of oxygen components, and 1 to 5000 ppm of halogen components.

5. In paragraph 1, The above dehydrogenation catalyst is a method for producing light olefins from waste plastic, which is a composite catalyst in which an active metal is supported on a carrier.

6. In paragraph 5, A method for producing light olefins from waste plastic, wherein the active metal of the above dehydrogenation catalyst is Co, Cr, Pt or a mixture thereof.

7. In paragraph 6, A method for producing light olefin from waste plastic, wherein the active metal for dehydrogenation further comprises B, Ce, La, Zr, Zn, Sn, Re, Ga or a mixture thereof.

8. In paragraph 5, A method for producing light olefins from waste plastics, wherein the support of the above dehydrogenation catalyst is alumina, silica, titania, 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.

9. In paragraph 1, A method for producing light olefins from waste plastic, wherein the cracking catalyst is zeolite, clay, SAPO (silica-alumina-phosphate), ALPO (aluminum phosphate), MOF (Metal Organic Framework), amorphous silica-alumina or a mixture thereof.

10. In paragraph 9, A method for producing light olefins from waste plastic, wherein the zeolite of the cracking catalyst comprises at least one 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.

11. In paragraph 9, A method for producing light olefins from waste plastics, wherein the cracking catalyst further comprises a support 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.

12. In paragraph 9, The above cracking catalyst is a method for producing light olefins from waste plastics into which phosphorus (P) has been introduced.

13. In paragraph 1, Step b) above is a method for producing light olefins from waste plastics using one or more fixed bed reactors or circulating fluidized bed reactors.

14. In paragraph 1, The above step b) is carried out at a reaction temperature of 300 to 900 ℃ for 0.5 to 50 h. -1 A method for producing light olefins from waste plastics, the method being performed at a space velocity of .

15. In paragraph 1, A method for producing light olefins from waste plastic, wherein the reactor of step b) is arranged so that the cracking catalyst is located at the top, the dehydrogenation catalyst is located at the bottom, and the cracking catalyst is located at the bottom.

16. In paragraph 15, A method for producing light olefins from waste plastic, 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.

17. In paragraph 1, A method for producing light olefins from waste plastic, wherein the reactor of step b) is arranged so that the dehydrogenation catalyst is located at the top and the cracking catalyst is located at the bottom.

18. In paragraph 17, A method for producing light olefins from waste plastic, wherein the reactor comprises 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.

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