ENERGY SAVING DEVICE AND METHOD FOR PRODUCING OLEFIN COMPOUND BY DECOMPOSING PLASTIC WASTE USING Organic-Inorganic Hybrid nanoporous materials

Abstract

According to one embodiment of the present invention, an energy-saving olefin production method is provided for producing olefins and effective gas from the decomposition of waste plastics, comprising: a waste plastic decomposition step of decomposing waste plastics to generate a mixed gas containing hydrogen, methane, and a hydrocarbon with two or more carbon atoms; an acetylene adsorption step of adsorbing acetylene contained in the mixed gas; and a C2 separation step of adsorbing a hydrocarbon with two carbon atoms onto the acetylene removal mixed gas remaining after acetylene adsorption from the mixed gas, and obtaining an olefin from the adsorbed hydrocarbon with two carbon atoms, wherein an organic-inorganic hybrid nanoporous body that selectively adsorbs acetylene from the mixed gas is used in the acetylene adsorption step.

Description

Technology Field

[0001] The present invention relates to an apparatus and method for producing olefins from a mixed gas obtained from the decomposition of waste plastics, and is a technology capable of treating a mixed gas containing acetylene by utilizing an organic-inorganic hybrid nanoporous body. Background Technology

[0002] South Korea's annual per capita plastic consumption stands at 98.9 kg, the highest in the world compared to major countries. While waste plastics that could not be recycled domestically were previously exported, the amendment to the Basel Convention came into effect in 2021, designating waste plastics as a hazardous waste subject to import and export controls. Consequently, there is a pressing need for effective recycling methods to address the increasing volume of waste plastics. Recycling methods are broadly categorized into mechanical and chemical recycling. Among these, chemical recycling involves converting polymer-based plastics back into their original monomer forms through chemical reactions. However, within chemical recycling, processes involving the pyrolysis and gasification of previously utilized waste plastics are difficult to classify as carbon-neutral disposal methods due to the significant energy consumption associated with the heating process.

[0003] To address this issue, a technology has been devised to decompose waste plastics into raw materials such as ethylene using plasma. However, the plasma treatment method has a problem in that process efficiency is reduced due to the large amount of acetylene generated during the process of decomposing waste plastics with plasma. The problem to be solved

[0004] The purpose of the present invention is to provide a method and apparatus for separating useful raw materials, such as hydrogen, methane, or hydrocarbons, generated during the process of decomposing waste plastics.

[0005] In addition, the purpose of the present invention is to implement a process for separating and producing olefins, which are useful raw materials, in an energy-saving manner. means of solving the problem

[0006] According to one embodiment of the present invention, an energy-saving olefin production method is provided for producing olefins and effective gas from the decomposition of waste plastics, comprising: a waste plastic decomposition step of decomposing waste plastics to generate a mixed gas containing hydrogen, methane, and a hydrocarbon having two or more carbon atoms; an acetylene adsorption step of adsorbing acetylene contained in the mixed gas; and a C2 separation step of adsorbing a hydrocarbon having two carbon atoms onto the acetylene removal mixed gas remaining after acetylene adsorption from the mixed gas, and obtaining an olefin from the adsorbed hydrocarbon having two carbon atoms, wherein an organic-inorganic hybrid nanoporous body that selectively adsorbs acetylene from the mixed gas is used in the acetylene adsorption step.

[0007] According to one embodiment of the present invention, an energy-saving olefin production method is provided, wherein an acetylene conversion step is additionally performed between the waste plastic decomposition step and the acetylene adsorption step to convert at least a portion of the acetylene (C2H2) contained in the mixed gas into ethylene (C2H4).

[0008] According to one embodiment of the present invention, an energy-saving olefin production method is provided in which acetylene separated from the mixed gas by being adsorbed onto the organic-inorganic hybrid nanoporous body in the acetylene adsorption step is transferred to the acetylene conversion step and converted into ethylene.

[0009] According to one embodiment of the present invention, an energy-saving olefin production method is provided, wherein the acetylene adsorption step is performed by a pressure conversion adsorption method in a vacuum environment.

[0010] According to one embodiment of the present invention, an energy-saving olefin production method is provided in which, in the C2 separation step, a hydrocarbon having 2 carbon atoms is adsorbed and then hydrogen and methane are separated, and the separated hydrogen and methane are transferred to the waste plastic decomposition step and utilized for the decomposition of waste plastic.

[0011] According to one embodiment of the present invention, an energy-saving olefin production method is provided, wherein the C2 separation step further includes a separation step of ethane (C2H6) and ethylene (C2H4).

[0012] According to one embodiment of the present invention, an energy-saving olefin production method is provided in which, in the separation step of ethane (C2H6) and ethylene (C2H4), ethane is selectively adsorbed to separate ethane and ethylene.

[0013] According to one embodiment of the present invention, an energy-saving olefin production method is provided in which at least one organic-inorganic hybrid nanoporous body having an ethane selectivity of 2.5 or higher is provided in the separation step of ethane (C2H6) and ethylene (C2H4).

[0014] According to one embodiment of the present invention, an energy-saving olefin production method is provided, which further includes the step of decomposing the separated ethane (C2H6) gas after the C2 separation step in a plasma reactor or a pyrolysis reactor to generate hydrogen, and supplying the generated hydrogen to a waste plastic decomposition step.

[0015] According to one embodiment of the present invention, an energy-saving olefin separation device is provided, comprising: a waste plastic decomposition furnace for decomposing waste plastic into a mixed gas form; an acetylene adsorption unit for adsorbing acetylene contained in the mixed gas; and a C2 separation unit for adsorbing a hydrocarbon having two carbon atoms on the acetylene removal mixed gas remaining after acetylene adsorption from the mixed gas, and discharging residual hydrogen and methane, wherein the acetylene adsorption unit is provided with an organic-inorganic hybrid nanoporous body that selectively adsorbs acetylene among hydrogen, methane, and hydrocarbon having two carbon atoms contained in the mixed gas.

[0016] According to one embodiment of the present invention, an energy-saving olefin separation device is provided, further comprising an acetylene conversion unit that converts at least a portion of the acetylene (C2H2) contained in the mixed gas into ethylene (C2H4).

[0017] According to one embodiment of the present invention, an energy-saving olefin production apparatus is provided, wherein the acetylene conversion unit includes a catalyst bed for converting acetylene into ethylene, and hydrogen (H2) and acetylene (C2H2) in the mixed gas react in the catalyst bed to be converted into ethylene (C2H4).

[0018] According to one embodiment of the present invention, an energy-saving olefin production apparatus is provided, wherein the C2 separation unit comprises an organic-inorganic hybrid nanoporous body for selectively adsorbing ethylene and ethane from the acetylene removal mixed gas.

[0019] According to one embodiment of the present invention, an energy-saving olefin production apparatus is provided, which further comprises a separation membrane or an adsorption tower for separating hydrogen and methane with respect to the hydrogen and methane discharged from the C2 separation unit.

[0020] According to one embodiment of the present invention, an energy-saving olefin production apparatus is provided, further comprising an ethane adsorption unit for selectively adsorbing ethane to separate ethane (C2H6) and ethylene (C2H4) desorbed from the C2 separation unit.

[0021] According to one embodiment of the present invention, an energy-saving olefin production apparatus is provided, wherein at least one organic-inorganic hybrid nanoporous body having a value of 2.5 or higher is provided. Effects of the invention

[0022] According to the present invention, olefins can be effectively produced from the mixed gas generated during the waste plastic splitting process.

[0023] In addition, according to the present invention, olefins can be produced while saving energy because selective adsorption of gas using an organic-inorganic hybrid nanoporous body is utilized in the process of decomposing waste plastics to obtain useful raw materials such as hydrogen or methane. Brief explanation of the drawing

[0024] FIG. 1 is a block diagram showing an energy-saving olefin production method according to one embodiment of the present invention. FIG. 2 is a block diagram showing an olefin production process according to another embodiment of the present invention. Figure 3 illustrates an organic-inorganic hybrid nanoporous body used for acetylene adsorption according to one embodiment of the present invention. FIG. 4 is a schematic diagram briefly illustrating the form of an energy-saving olefin production device according to one embodiment of the present invention. Figure 5 is the result of a breakthrough test of an organic-inorganic hybrid nanoporous body used for acetylene adsorption according to one embodiment of the present invention. Figure 6 is the result of a gas separation ability test of an organic-inorganic hybrid nanoporous body used for acetylene adsorption according to one embodiment of the present invention. Figure 7 is the result of a breakthrough test of an organic-inorganic hybrid nanoporous body used for C2 adsorption according to one embodiment of the present invention. Figure 8 is the result of a stability test of an organic-inorganic hybrid nanoporous body used for C2 adsorption according to one embodiment of the present invention. Figure 9 shows the gas separation ability test results of an organic-inorganic hybrid nanoporous body used for ethane adsorption according to one embodiment of the present invention. Specific details for implementing the invention

[0025] The present invention is capable of various modifications and may take various forms, and specific embodiments are illustrated in the drawings and described in detail in the text. However, this is not intended to limit the invention to the specific disclosed forms, and it should be understood that the invention includes all modifications, equivalents, and substitutions that fall within the spirit and scope of the invention.

[0026] According to one embodiment of the present invention, acetylene gas generated in large quantities during the process of decomposing waste plastics is treated by utilizing an acetylene adsorption process utilizing an organic-inorganic hybrid nanoporous body, and thereby useful raw materials such as ethylene, ethane, hydrogen, or methane, particularly olefins, can be obtained.

[0027] FIG. 1 is a block diagram showing an energy-saving olefin production method according to one embodiment of the present invention.

[0028] An energy-saving olefin production method according to one embodiment of the present invention comprises: a waste plastic decomposition step (S100) for decomposing waste plastic to generate a mixed gas containing hydrogen, methane, and a hydrocarbon with two or more carbon atoms; an acetylene adsorption step (S200) for adsorbing acetylene contained in the mixed gas; and a C2 separation step (S300) for adsorbing a hydrocarbon with two carbon atoms onto the acetylene removal mixed gas remaining after acetylene adsorption from the mixed gas, and obtaining an olefin from the adsorbed hydrocarbon with two carbon atoms, wherein an organic-inorganic hybrid nanoporous body that selectively adsorbs acetylene from the mixed gas is used in the acetylene adsorption step to produce olefins and effective gas from the decomposition of waste plastic.

[0029] Below, we examine each step of the olefin production process according to an embodiment of the present invention.

[0030] First, in the waste plastic decomposition step (S100), waste plastic is supplied, and a process is performed to decompose the supplied waste plastic into low molecular weight chemical substances by heat or plasma treatment.

[0031] The waste plastic decomposed in the waste plastic decomposition step (S100) may be a polymer compound containing a hydrocarbon backbone. For example, the waste plastic may be polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polystyrene (PS), polyester (PET), etc. These materials may be decomposed in the waste plastic decomposition step (S100) into low molecular weight chemicals, for example, hydrogen or C1 to C4 hydrocarbon compounds.

[0032] When a pyrolysis method is used in the waste plastic decomposition step (S100), the pyrolysis can be performed at approximately 500 to 1000°C. The pyrolysis temperature may vary depending on the type of waste plastic, and when waste plastic is processed individually, it may be performed at the highest pyrolysis temperature. When processing a mixture of various waste plastics, the pyrolysis may be performed by gradually changing the temperature between the highest pyrolysis temperature of the mixed waste and the lowest pyrolysis temperature of the mixed waste.

[0033] When plasma treatment is used in the waste plastic decomposition step (S100), "plasma" is a form of matter known as a fourth state of matter other than solid, liquid, and gas, and low-temperature plasma (or non-equilibrium plasma) or high-temperature plasma may be utilized. In one embodiment of the present invention, the plasma may be generated by a dielectric barrier discharge (DBD) method, specifically, electrical characteristics that generate plasma ions by passing electricity through electrodes on both sides of a dielectric may be utilized. The plasma may be generated by an arc plasma discharge, and the process temperature for waste plastic decomposition may be controlled to be between 450°C and 1300°C.

[0034] When using plasma to decompose waste plastic in the waste plastic decomposition step (S100), not only single-type plastics but also mixed waste plastics containing various types of plastics can be effectively decomposed. In the case of general pyrolysis methods, combustion of waste plastics begins from the outer surface and moves inward, but the supply of combustion air is not smooth, resulting in unburned fuel during combustion and many problems with combustion control. Furthermore, in the case of thermosetting resins, recycling is even more difficult because many inorganic materials are used as reinforcing agents. Since the decomposition processes for mixed waste plastics are different and difficult, a direct gasification high-temperature process is required, but research on this is lacking. Therefore, in one embodiment of the present invention, mixed waste plastics can also be effectively decomposed by utilizing plasma.

[0035] In the waste plastic decomposition step (S100), waste plastic is decomposed to generate a mixed gas containing hydrogen, methane, and hydrocarbons with two or more carbon atoms. The mixed gas may contain hydrogen, methane and ethane (C2H6), ethylene, and acetylene. In addition to the chemical substances described above, hydrocarbons having two or more carbon atoms, such as C3 hydrocarbons (propane, propylene, etc.) and C4 hydrocarbons (butane, butylene, etc.), may be included in gaseous form. However, the concentration of C3 hydrocarbons and C4 hydrocarbons in the mixed gas is lower than the concentration of hydrogen or C1 to C2 hydrocarbons. This is because C3 hydrocarbons or C4 hydrocarbons, which have relatively long hydrocarbon chain lengths, are decomposed relatively easily by plasma treatment or heat treatment in the waste plastic decomposition step (S100) and converted into hydrogen or C1 to C2 hydrocarbons.

[0036] The mixed gas generated in the waste plastic decomposition step (S100) is transferred along the piping to a process for acetylene adsorption.

[0037] The acetylene adsorption step (S200) for adsorbing acetylene contained in the mixed gas is performed using an organic-inorganic hybrid nanoporous body capable of selectively adsorbing acetylene within a mixed gas containing various types of chemicals.

[0038] In the acetylene adsorption step (S200), acetylene can be separated from the mixed gas using the Pressure Swing Adsorption (PSA) method. Pressure Swing Adsorption is a technology that separates gases by utilizing the difference in adsorption amounts according to pressure differences using an adsorbent that adsorbs specific gases. When pressure swing adsorption is performed, gases contained in the mixed gas are adsorbed into the pores of the organic-inorganic hybrid nanoporous material when pressurized, and when the pressure is slowly reduced, gases with weak attractive forces with the organic-inorganic hybrid nanoporous material are desorbed from the pores and separated. At this time, since acetylene molecules have strong attractive forces with the organic-inorganic hybrid nanoporous material, they are desorbed from the organic-inorganic hybrid nanoporous material at a lower pressure range than other types of gases. Therefore, by gradually lowering the pressure, acetylene can be separated from the mixed gas using the organic-inorganic hybrid nanoporous material.

[0039] In the acetylene adsorption step (S200), pressure swing adsorption can be performed in a vacuum environment. Accordingly, a high-temperature environment is not required in the acetylene adsorption step (S200). Conventionally, a Temperature Swing Adsorption (TSA) method was utilized, which takes advantage of the change in the amount of gas adsorbed and desorbed within the pores according to temperature. However, in the temperature swing adsorption method, there was a problem that acetylene could react during the process of raising the temperature to desorb gas from the adsorbent. In addition, there was a problem that a large amount of energy was required to raise the temperature and the adsorption and desorption process took a long time. In contrast, by using the pressure swing adsorption method, there is no risk of acetylene reacting during the process of adsorbing and desorbing acetylene in the organic-inorganic hybrid nanoporous body, and energy can be saved because it is performed in a vacuum environment. Conventionally, off-gas containing 20 to 30 vol.% or less of olefin was used for power generation because the energy required for olefin separation was high. However, according to the present invention, olefins can be produced by separating the gas generated from the decomposition of waste plastics in an energy-saving manner.

[0040] After performing the acetylene adsorption step (S200), C3 hydrocarbons and C4 hydrocarbons can also be separated along with acetylene from the mixed gas. After the acetylene adsorption step (S200), the mixed gas can be divided into a mixture of acetylene, C3 hydrocarbons and C4 hydrocarbons and a mixture of hydrogen, methane, ethane, and ethylene. The mixture of hydrogen, methane, ethane, and ethylene, i.e., the acetylene removal mixed gas, is transferred to the next step.

[0041] A C2 separation step (S300) is performed to adsorb carbon-2 hydrocarbons to the transported acetylene removal mixed gas and discharge residual hydrogen and methane.

[0042] In the C2 separation step (S300), a hydrocarbon with two carbon atoms is adsorbed onto the acetylene removal mixed gas remaining after acetylene adsorption from the mixed gas, and an olefin is obtained from the adsorbed hydrocarbon with two carbon atoms.

[0043] In the C2 separation step (S300), for example, hydrocarbons of hydrocarbon 2, namely ethane and ethylene, are adsorbed using an adsorbent, and hydrogen and methane are discharged. For this purpose, an organic-inorganic hybrid nanoporous body may be used. In particular, in the C2 separation step (S300), the adsorbed ethane and ethylene may be separated to obtain ethylene. To this end, ethane may be selectively adsorbed among ethane and ethylene, or ethylene may be selectively adsorbed among ethane and ethylene to produce olefin (ethylene).

[0044] The organic-inorganic hybrid nanoporous material used in the C2 separation step (S300) may be of a different type from the organic-inorganic hybrid nanoporous material used in the acetylene adsorption step (S200) mentioned earlier. For example, in the C2 separation step (S300), an organic-inorganic hybrid nanoporous material in which 2,6-naphthalenedicarboxylate is bonded to an Al central metal ion as a linker ligand may be used. Here, since acetylene is not present in the mixed gas introduced into the organic-inorganic hybrid nanoporous material or the acetylene concentration is low enough to be negligible, there is no concern that acetylene will bind to the organic-inorganic hybrid nanoporous material.

[0045] Acetylene is a highly reactive gas, and generally, when acetylene is mixed with other C2 and C1 hydrocarbons, the acetylene binds more strongly to the adsorbent, making it difficult to separate the other gases. In particular, since acetylene bound to the adsorbent is not easily separated from the adsorbent, the amount of acetylene bound to the adsorbent increases as the gas separation process is repeated. Consequently, the adsorption capacity of the adsorbent decreases, making it difficult to continue the separation process. Therefore, conventionally, measures such as adding an acetylene conversion unit to the process were taken to eliminate acetylene. However, under high acetylene concentration conditions where the acetylene concentration is close to 30 vol.%, there was a problem in that acetylene conversion was not performed smoothly or too much energy was consumed for acetylene conversion. In one embodiment of the present invention, since all of the high concentration of acetylene gas can be adsorbed through the acetylene adsorption step (S200) prior to the C2 separation step (S300), a smooth separation process can be performed.

[0046] In the C2 separation step (S300), ethane, ethylene, hydrogen, and methane can also be separated through pressure-circulating adsorption. That is, ethane, ethylene, hydrogen, and methane can be separated by increasing the pressure to adsorb the acetylene removal mixed gas into the pores of the organic-inorganic hybrid nanoporous body, and then lowering the pressure to separate hydrogen and methane first.

[0047] By utilizing the aforementioned olefin production method, raw gas can be separated by component even when a mixed gas containing high concentrations of acetylene is generated after the decomposition of waste plastic. Therefore, the decomposition and separation processes can be performed efficiently regardless of the type of waste plastic.

[0049] Below, we examine an olefin production process according to another embodiment in which additional processes are added to the basic embodiment of the olefin production process described above.

[0050] FIG. 2 is a block diagram showing an olefin production process according to another embodiment of the present invention.

[0051] Referring to FIG. 2, between the waste plastic decomposition step (S100) and the acetylene adsorption step (S200), an acetylene conversion step (S150) may be additionally performed to convert at least a portion of the acetylene (C2H2) contained in the mixed gas into ethylene (C2H4).

[0052] The acetylene conversion step (S150) may refer to a reaction process that converts acetylene into ethylene by reacting it with hydrogen contained in the mixed gas. At this time, hydrogen may be supplied from an external source if necessary. For example, a portion of the hydrogen obtained after performing the olefin production process may be supplied to the acetylene conversion step (S150).

[0053] The acetylene conversion step (S150) can be performed when the concentration of acetylene in the mixed gas is too high. For example, when the concentration of acetylene in the mixed gas exceeds 10 vol.%, the acetylene concentration can be lowered through acetylene conversion. When the concentration of acetylene is lowered to a certain level, not only can the subsequent acetylene adsorption step (S200) be performed more efficiently, but the concentration of ethylene, a useful raw material in the gas, is increased, which has the effect of increasing the amount of resources generated after the decomposition of waste plastic is completed.

[0054] The acetylene conversion step (S150) can be performed in an acetylene conversion unit, which includes a catalyst bed for converting acetylene into ethylene, and hydrogen (H2) and acetylene (C2H2) in the mixed gas can react in the catalyst bed to be converted into ethylene (C2H4). For example, a Pd-Nb catalyst can be used as a catalyst for acetylene conversion, but various other types of catalysts can be used as long as they can convert acetylene into ethylene.

[0055] After the acetylene conversion step (S150), the mixed gas in which at least some of the acetylene is converted into ethylene is transferred to the acetylene adsorption step (S200).

[0056] In the acetylene adsorption step (S200), acetylene is separated by selectively adsorbing it using an organic-inorganic hybrid nanoporous body as described above. The separated acetylene gas is then supplied back to the acetylene conversion unit along with C3 and C4 hydrocarbon gases and can be used in the acetylene conversion step (S150). Accordingly, through the repetition of the acetylene conversion step (S150) and the acetylene adsorption step (S200), acetylene can ultimately be entirely converted into ethylene, a useful resource.

[0057] After the C2 separation step (S300), the separated C2 gases, namely ethylene and ethane, can also be separated. That is, the C2 separation step (S300) may additionally include a separation step (S310) of ethane (C2H6) and ethylene (C2H4).

[0058] In the separation step (S310) of ethane and ethylene, an adsorbent having different adsorption capacities for ethane (C2H6) and ethylene (C2H4) may be used. The adsorbent may selectively adsorb ethane from the mixed gas of ethane and ethylene. Accordingly, ethane from the mixed gas of ethane and ethylene is adsorbed by the adsorbent, and the unadsorbed ethylene is captured to obtain olefin (ethylene), a useful resource. In some cases, ethylene may be adsorbed by the adsorbent, and the unadsorbed ethane may be discharged first, and then the adsorbed ethylene may be desorbed to obtain olefin (ethylene), a useful resource. Which adsorbent to use in the separation step (S310) of ethane and ethylene can be determined by considering the type of waste plastic, the scale of the process, and the estimated relative amounts of ethane and ethylene generated from the decomposition of waste plastic.

[0059] In the separation step (S310) of ethane and ethylene, at least one organic-inorganic hybrid nanoporous body with a value of 2.5 or higher may be used. This means that ethane can be selectively adsorbed from the mixed gas of ethane and ethylene. Ethane selectivity can be calculated as the ratio of the amount of ethane adsorbed to the amount of ethylene adsorbed during the adsorption of the mixed gas.

[0060] The adsorbent utilized in the separation step (S310) of ethane and ethylene may be an organic-inorganic hybrid nanoporous body. For example, an organic-inorganic hybrid nanoporous body comprising at least one linker ligand selected from the group consisting of 2,6-naphthalenedicarboxylate, 4,4'-biphenyldicarboxylate, 3,5-pyridinedicarboxylate, 2,5-furandicarboxylate, 2,5-thiophenedicarboxylate, and 3,5-1H-pyrazoledicarboxylate may be used as an adsorbent for separating ethane and ethylene. In one embodiment of the present invention, at least three gas separation processes may be included within the olefin production process, including selective adsorption of acetylene, selective adsorption of ethylene and ethane, and separation of ethylene and ethane, and for this purpose, different species of organic-inorganic hybrid nanoporous bodies may be utilized in each separation step.

[0061] The separation step (S310) of ethane and ethylene can also be performed through pressure-circulating adsorption. The ethane and ethylene separated in this way can each be separated and captured and utilized as useful resources.

[0062] After the C2 separation step (S300), methane and hydrogen separated from the C2 gas can also be separated. In the methane and hydrogen separation step (S320), methane and hydrogen can be separated, for example, by utilizing a separation membrane or adsorption tower having selective permeability to methane and hydrogen. The separated methane and hydrogen can each be captured and utilized as useful resources.

[0063] In some cases, methane and hydrogen may not be separated and may be transferred to the plasma decomposition step (S100). The methane and hydrogen transferred to the plasma decomposition step (S100) can be utilized as plasma reaction species. That is, high-energy electrons generated in the plasma collide with hydrogen and methane, and radical species containing radicals within the molecules can be formed. These formed radical species can then collide with waste plastic to break the carbon chains within the waste plastic, thereby generating C1 to C4 low-molecular-weight hydrocarbon gases.

[0064] Previously, the ethane (C2H6) gas separated in the ethane and ethylene separation step (S310) can be decomposed in a plasma reactor and converted into hydrogen gas. The hydrogen generated at this time can be supplied to the waste plastic decomposition step. The manner in which the supplied hydrogen is utilized for waste plastic decomposition is the same as previously described.

[0065] According to one embodiment of the present invention, a decomposition process can be performed even on composite waste plastics capable of generating a large amount of acetylene gas, and useful resources such as ethane and hydrogen can be captured through gas separation during the decomposition process, and other separated gases can also be utilized to increase the efficiency of the olefin production process through gas reuse. The above-described olefin production process can be implemented by including multiple types of organic-inorganic hybrid nanoporous bodies having different gas adsorption capacities.

[0066] Below, we will examine in more detail the organic-inorganic hybrid nanoporous body utilized in the present invention.

[0067] Figure 3 illustrates an organic-inorganic hybrid nanoporous body used for acetylene adsorption according to one embodiment of the present invention.

[0068] The organic-inorganic hybrid nanoporous body utilized in the acetylene adsorption step (S200) comprises a central metal ion provided within a crystal lattice; and a ligand linker that connects the crystal lattice containing the central metal ion with an adjacent crystal lattice in a planar manner.

[0069] In addition, the crystal lattice and the ligand linker are connected in a planar form containing pores, and molecules can be adsorbed within the pores. The central metal ion may be an ion of one or more metals selected from the group consisting of trivalent metals such as vanadium (V), chromium (Cr), iron (Fe), aluminum (Al), gallium (Ga), indium (In), and lanthanide metals. The central metal ion may be provided within the crystal lattice.

[0070] The central metal ion is provided in the form described above, forming crystal lattice-ligand linker-crystal lattice bonds on a planar surface or crystal lattice-crystal lattice bonds in a direction penetrating the plane. Accordingly, the organic-inorganic hybrid nanoporous body is provided in a form containing pores, and molecules provided within the pores can be adsorbed by receiving electrostatic attraction from the crystal lattice and ligand linker.

[0071] Multiple linker ligands may be provided between adjacent crystal lattices. For example, two linker ligands may be provided between two adjacent crystal lattices to connect the adjacent crystal lattices. The number of linker ligands may vary depending on the shape of the crystal lattice, etc. The linker ligands and the crystal lattice form a crystal lattice-linker ligand-crystal lattice bonding structure in a planar plane. Accordingly, when viewed in a planar plane, multiple crystal lattices and multiple linker ligands may be arranged in a form that forms pores. For example, multiple crystal lattices may form checkerboard-shaped vertices, and multiple pores may be provided by linker ligands being provided as line segments connecting each vertex. However, what is described above and illustrated in the drawings are exemplary arrangement forms of linker ligands and crystal lattices, and the pores may be arranged to have other shapes, such as rhombuses, hexagons, octagons, etc. In the above description, the term "plane" can be interpreted in a broad sense that includes both a plane in a mathematical sense and a level of the same.

[0072] The linker ligand may be 2,5-furandicarboxylate.

[0073] The above-described organic-inorganic hybrid nanoporous body can selectively adsorb acetylene within the pores formed by linker ligands and central metal ions. This is because the attractive force between the linker ligands and acetylene can be greater than the attractive force between ethane, ethylene, hydrogen, and methane, and accordingly, acetylene can be selectively adsorbed from the mixed gas.

[0075] FIG. 4 is a schematic diagram briefly illustrating the form of an energy-saving olefin production device according to one embodiment of the present invention.

[0076] According to one embodiment of the present invention, an energy-saving olefin separation device is provided, comprising: a waste plastic decomposition furnace for decomposing waste plastic into a mixed gas form; an acetylene adsorption unit for adsorbing acetylene contained in the mixed gas; and a C2 separation unit for adsorbing a hydrocarbon having two carbon atoms on the acetylene removal mixed gas remaining after acetylene adsorption from the mixed gas, and discharging residual hydrogen and methane, wherein the acetylene adsorption unit is provided with an organic-inorganic hybrid nanoporous body that selectively adsorbs acetylene among hydrogen, methane, and hydrocarbon having two carbon atoms contained in the mixed gas.

[0077] Although not illustrated in the drawings, the waste plastic decomposition furnace included within the energy-saving olefin separation device may be composed of equipment capable of plasma discharge and a chamber containing the plasma and waste plastic. The equipment capable of plasma discharge may be, for example, a DBD device or an arc discharge device. The chamber is provided in a sealed form and may be equipped with piping and a pump to transport the mixed gas generated after the decomposition of waste plastic. However, in some cases, the waste plastic decomposition furnace included within the energy-saving olefin separation device may be a device that decomposes waste plastic using heat rather than plasma. Whether to implement the waste plastic decomposition furnace using a thermal decomposition method or a plasma decomposition method can be selected by considering the type of waste plastic, the installation location of the process, and other factors.

[0078] The acetylene adsorption section and C2 separation section within the energy-saving olefin production device may be provided in the form of an adsorption tower as illustrated in the drawing. In this case, an organic-inorganic hybrid nanoporous material may be provided in the form of a bed within the adsorption tower. The organic-inorganic hybrid nanoporous material bed is positioned to come into contact with the mixed gas passing through the adsorption tower, and the gas may be separated during this process. One or multiple adsorption towers may be provided, and the number of adsorption towers can be determined by considering the processing capacity of the energy-saving olefin production device. The organic-inorganic hybrid nanoporous material may be provided as independent particles or in combination with other substrates.

[0079] In addition, the acetylene adsorption section and the C2 separation section may further include pumps capable of changing pressure to perform pressure circulation separation. In particular, since pressure circulation separation can be performed under vacuum conditions, a vacuum pump may be further provided to create a vacuum inside the adsorption tower.

[0080] Each adsorption unit can be connected via a transfer pipe, and each transfer pipe may be provided with a pump to facilitate the smooth flow of gas. The transfer pipes can be coupled to the adsorption towers, taking into account the molecular weight of the gas being separated from the mixed gas. For example, the piping for discharging acetylene and C3, C4 hydrocarbon gases from the acetylene adsorption unit can be connected to the bottom of the acetylene adsorption unit, because acetylene and C3, C4 hydrocarbon gases are heavier than ethylene, ethane, methane, and hydrogen. Conversely, the piping for discharging ethylene, ethane, methane, and hydrogen can be connected to the top of the acetylene adsorption unit. The piping for discharging ethane, methane, and hydrogen can extend from the top of the acetylene adsorption unit and be connected to the bottom of the C2 separation unit. Additionally, piping for discharging the relatively lighter remaining gases, methane and hydrogen, can be connected to the top of the C2 separation unit. In this way, the transfer piping can be connected to the adsorption unit by taking into account the molecular weight of each gas separated in the gas separation process.

[0081] Each pipe and adsorption section may be additionally provided with a purge device to remove residual gas.

[0082] An ethane adsorption unit may be additionally provided in the C2 separation unit, and the ethane adsorption unit can separate ethylene and ethane from a mixed gas of ethylene and ethane as described above. An organic-inorganic hybrid nanoporous body having an ethane selectivity of 2.5 or higher may be provided in the ethane adsorption unit. This means that ethane can be selectively adsorbed from a mixed gas of ethane and ethylene.

[0084] Figure 5 is the result of a breakthrough test of an organic-inorganic hybrid nanoporous body used for acetylene adsorption according to one embodiment of the present invention.

[0085] Figure 5 shows the time required for the adsorbed gas to be desorbed from the organic-inorganic hybrid nanoporous body when hydrogen, methane, ethane, ethylene, acetylene, and propylene gases are supplied to the organic-inorganic hybrid nanoporous body according to Figure 3, respectively.

[0086] Referring to the drawings, the time required for desorption from the organic-inorganic hybrid nanoporous material was short in the order of hydrogen < methane < ethylene < ethane < propylene < acetylene. Therefore, it can be seen that the adsorption force between acetylene and the organic-inorganic hybrid nanoporous material is strong, and that acetylene can be separated from other types of gases using this. In particular, there is a large difference in the time at which the gas begins to be separated between acetylene and other types of gases; while acetylene begins to be separated after about 1400 seconds, propylene, which is the slowest to be separated among other types of gases, is separated in the 800-second range. This suggests that acetylene can be separated from other types of gases with high accuracy by utilizing the organic-inorganic hybrid nanoporous material according to one embodiment of the present invention.

[0088] Figure 6 is the result of a gas separation ability test of an organic-inorganic hybrid nanoporous body used for acetylene adsorption according to one embodiment of the present invention.

[0089] Figure 6 shows the separation results when adsorption-desorption was performed on a mixture of hydrogen, methane, ethane, ethylene, acetylene, and propylene gases at a flow rate of approximately 500 cc / min in an environment of 25 ℃ and 5 bar (left), and the separation results when adsorption-desorption was performed on the same gases at a flow rate of approximately 740 cc / min in an environment of 40 ℃ and 10 bar (right).

[0090] Referring to the left graph of Fig. 6, it can be seen that for the mixed gas, propylene and acetylene gases are separated at approximately 100 minutes, which is significantly later than hydrogen, methane, ethane, and ethylene. Additionally, the right graph shows that propylene and acetylene gases are separated at approximately 80 minutes, allowing for the separation of hydrogen, methane, ethane, ethylene, acetylene, and propylene.

[0091] The acetylene and propylene separated in this way can be transferred to an acetylene conversion unit as described above and converted back into ethylene.

[0092] In addition, by referring to the graph in the drawing, it was confirmed that separation between acetylene, porphyllene, and other gas species is possible even when the temperature is raised to 40 ℃ and the gas flow rate is raised to 740 cc / min, so it can be seen that the efficiency of the olefin production process can be increased by raising the temperature and gas flow rate as needed.

[0094] Figure 7 is the result of a breakthrough test of an organic-inorganic hybrid nanoporous body used for C2 adsorption according to one embodiment of the present invention.

[0095] Referring to Fig. 7, it can be seen that hydrogen, methane, ethane, and ethylene can be separated using an organic-inorganic hybrid nanoporous material (CAU-3-NDCA) in the C2 separation section. It can be confirmed that hydrogen, methane, ethane, and ethylene are separated from the organic-inorganic hybrid nanoporous material at the time interval when they are distinguished from each other in environments where the temperature is 25°C or 40°C and the pressure is 5 bar or 10 bar as shown in the figure.

[0096] Therefore, from the experimental results described above, it can be seen that hydrogen, methane, ethane, and ethylene can be separated by providing an organic-inorganic hybrid nanoporous body to the C2 separation unit, and in some cases, hydrogen, methane, ethane, and ethylene can be separated individually using only the C2 separation unit without a separate ethane and ethylene separation unit.

[0098] Figure 8 is the result of a stability test of an organic-inorganic hybrid nanoporous body used for C2 adsorption according to one embodiment of the present invention.

[0099] Referring to Fig. 8, the purity of each gas can be determined when the separation of hydrogen, methane, ethane, and ethylene is repeatedly performed using an organic-inorganic hybrid nanoporous body (CAU-3-NDCA) in the C2 separation section. Referring to the figure, it can be seen that there is almost no change in gas purity even when the separation process is repeated up to 20 times in environments with a temperature of 25 ℃ or 40 ℃ and a pressure of 5 bar or 10 bar.

[0100] In addition, the acetylene concentration in the C2 separation section was found to be 0.0, indicating that the acetylene was substantially completely removed before reaching the C2 separation section.

[0101] Meanwhile, when one adsorption tower was used in the C2 separation section, the recovery rate of C2 (ethane, ethylene) was analyzed to be 60–75%, and when two or more adsorption towers were used, the recovery rate of C2 (ethane, ethylene) was analyzed to be 90–95%.

[0102] Therefore, from the experimental results of Fig. 8, it can be seen that all acetylene strongly bound to the organic-inorganic hybrid nanoporous material provided to the C2 separation section is removed, and accordingly, hydrogen, methane, ethane, and ethylene are separated smoothly, and even if the process is repeated, there is no decrease in the adsorption capacity of the organic-inorganic hybrid nanoporous material due to acetylene adsorption. As such, it can be seen that the olefin production process according to one embodiment of the present invention can be performed even in an environment containing a high concentration of acetylene.

[0104] Figure 9 shows the gas separation ability test results of an organic-inorganic hybrid nanoporous body used for ethane adsorption according to one embodiment of the present invention.

[0105] The organic-inorganic hybrid nanoporous material used in Fig. 9 is a Cu(Qc)2 adsorbent.

[0106] Referring to Fig. 9, ethane (C2H6) and ethylene (C2H4) showed distinctly different adsorption amounts on the organic-inorganic hybrid nanoporous material across all pressure ranges (greater than 0.0 bar and less than or equal to 1.0 bar) and all separation process execution times (1 hour to 12 hours). Specifically, it was observed that ethane was adsorbed in significantly greater quantities than ethylene on the organic-inorganic hybrid nanoporous material used for the separation of ethane (C2H6) and ethylene (C2H4), and it was confirmed that the change in adsorption amount when the pressure was changed was also greater for ethane than for ethylene. Therefore, it can be seen that when specific pressure conditions are formed in a gas mixed with ethane and ethylene, ethane is preferentially adsorbed onto the organic-inorganic hybrid nanoporous material compared to ethylene. Accordingly, ethylene that is not adsorbed on the organic-inorganic hybrid nanoporous material can be separated from the ethane adsorbed on the organic-inorganic hybrid nanoporous material and obtained.

[0107] Although the present invention has been described above with reference to preferred embodiments, those skilled in the art or those with ordinary knowledge in the art will understand that various modifications and changes can be made to the invention without departing from the spirit and technical scope of the invention as described in the claims set forth below.

[0108] Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification, but should be determined by the claims.

Claims

Claim 1 An energy-saving olefin production method for producing olefins and effective gas from the decomposition of waste plastics, comprising: a waste plastic decomposition step of decomposing waste plastics to generate a mixed gas containing hydrogen, methane, and a hydrocarbon with two or more carbon atoms; an acetylene adsorption step of adsorbing acetylene contained in the mixed gas; and a C2 separation step of adsorbing a hydrocarbon with two carbon atoms onto the acetylene removal mixed gas remaining after acetylene adsorption from the mixed gas, and obtaining an olefin from the adsorbed hydrocarbon with two carbon atoms, wherein an organic-inorganic hybrid nanoporous body that selectively adsorbs acetylene from the mixed gas is used in the acetylene adsorption step. Claim 2 An energy-saving olefin production method according to claim 1, wherein an acetylene conversion step is additionally performed between the waste plastic decomposition step and the acetylene adsorption step to convert at least a portion of the acetylene (C2H2) contained in the mixed gas into ethylene (C2H4). Claim 3 An energy-saving olefin production method according to claim 2, wherein acetylene separated from the mixed gas by being adsorbed onto the organic-inorganic hybrid nanoporous body in the acetylene adsorption step is transferred to the acetylene conversion step and converted into ethylene. Claim 4 An energy-saving olefin production method according to claim 1, wherein the acetylene adsorption step is performed by a pressure conversion adsorption method in a vacuum environment. Claim 5 An energy-saving olefin production method according to claim 4, wherein in the C2 separation step, hydrogen and methane are separated after adsorbing a hydrocarbon having 2 carbon atoms, and the separated hydrogen and methane are transferred to the waste plastic decomposition step and utilized for the decomposition of waste plastic. Claim 6 An energy-saving olefin production method according to claim 1, wherein the C2 separation step further includes a separation step of ethane (C2H6) and ethylene (C2H4). Claim 7 An energy-saving olefin production method according to claim 6, wherein in the separation step of ethane (C2H6) and ethylene (C2H4), ethane is selectively adsorbed to separate ethane and ethylene. Claim 8 An energy-saving olefin production method according to claim 7, wherein at least one organic-inorganic hybrid nanoporous body having an ethane selectivity of 2.5 or higher is used in the separation step of ethane (C2H6) and ethylene (C2H4). Claim 9 An energy-saving olefin production method according to claim 6, further comprising the step of decomposing the separated ethane (C2H6) gas after the C2 separation step in a plasma or pyrolysis reactor to generate hydrogen, and supplying the generated hydrogen to a waste plastic decomposition step. Claim 10 An energy-saving olefin separation device comprising: a waste plastic decomposition furnace for decomposing waste plastic into a mixed gas form; an acetylene adsorption unit for adsorbing acetylene contained in the mixed gas; and a C2 separation unit for adsorbing C2 hydrocarbons on the acetylene removal mixed gas remaining after acetylene adsorption from the mixed gas, and discharging residual hydrogen and methane, wherein the acetylene adsorption unit is provided with an organic-inorganic hybrid nanoporous body that selectively adsorbs acetylene among hydrogen, methane, and C2 hydrocarbons contained in the mixed gas. Claim 11 An energy-saving olefin separation device according to claim 10, further comprising an acetylene conversion unit that converts at least a portion of the acetylene (C2H2) contained in the mixed gas into ethylene (C2H4). Claim 12 An energy-saving olefin separation device according to claim 11, wherein the acetylene conversion unit comprises a catalyst bed for converting acetylene into ethylene, and hydrogen (H2) and acetylene (C2H2) in the mixed gas react in the catalyst bed to be converted into ethylene (C2H4). Claim 13 An energy-saving olefin separation device according to claim 10, wherein the C2 separation unit comprises an organic-inorganic hybrid nanoporous body for selectively adsorbing ethylene and ethane from the acetylene removal mixed gas. Claim 14 An energy-saving olefin separation device according to claim 10, further comprising a separation membrane or an adsorption tower for separating hydrogen and methane with respect to the hydrogen and methane discharged from the C2 separation unit. Claim 15 An energy-saving olefin separation device according to claim 10, further comprising an ethane adsorption unit for selectively adsorbing ethane to separate ethane (C2H6) and ethylene (C2H4) desorbed from the C2 separation unit. Claim 16 An energy-saving olefin separation device according to claim 15, wherein the ethane adsorption section is provided with at least one organic-inorganic hybrid nanoporous body having an ethane selectivity of 2.5 or higher.

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