Method for producing regenerated MMA from waste pmma

Abstract

The present disclosure may provide a method for producing regenerated MMA from waste PMMA, the method comprising the steps of: subjecting waste PMMA to low-temperature plasma depolymerization in the presence of a zeolite-based solid acid catalyst; and obtaining regenerated MMA from the waste PMMA depolymerized product produced in the step of subjecting the waste PMMA to low-temperature plasma depolymerization.

Description

Method for manufacturing recycled MMA from waste PMMA

[0001] The present disclosure provides a method for producing regenerated MMA by low-temperature plasma depolymerization of waste PMMA under a zeolite-based solid acid catalyst.

[0002] Plastics are widely used in various industrial and technological fields due to their excellent flexibility, productivity, impact resistance, handling, and moldability; however, because of their low density and, in particular, very low biodegradability, environmental pollution is caused by waste plastics.

[0003] Therefore, in order to solve the environmental pollution problem caused by the aforementioned waste plastics, various technological developments are underway, such as replacing them with eco-friendly materials or developing plastics with improved biodegradability.

[0004] However, the aforementioned eco-friendly materials and biodegradable plastics are expensive to produce, and because their physical properties are inferior to those of the aforementioned conventional virgin plastics, their applications are limited.

[0005] For the reasons mentioned above, among the methods to solve the environmental pollution problems caused by the aforementioned waste plastics, waste plastic recycling technology is attracting attention as it can consume large quantities of waste plastic and fundamentally reduce the production of new plastics.

[0006] The above waste plastic recycling technology can be classified into physical recycling technology, which removes impurities contained in waste plastic and crushes it to form it immediately, and chemical recycling technology, which depolymerizes waste plastic to produce usable recycled oil or recycled monomer.

[0007] However, the aforementioned conventional physical recycling technology cannot completely remove trace impurities contained in waste plastic, and since it is exposed to high heat during remolding, its physical properties are inevitably degraded compared to new plastic.

[0008] In particular, plastics such as polyurethane (PU), polymethylmethacrylate (PMMA), polycarbonate (PC), and polyethylene terephthalate (PET), which are conventionally used as transparent materials, are at risk of gradually losing transparency during physical recycling, so there are still many problems to solve regarding their recycling.

[0009] The aforementioned conventional chemical recycling of waste PET produces a product containing recycled ester oil upon depolymerization, which offers high utility. Furthermore, since ester bonds can be chemically depolymerized more easily, extensive recycling technology development is currently underway.

[0010] However, the chemical recycling process for obtaining MMA from the aforementioned waste PMMA requires a large amount of thermal energy and has a very low yield, so it is still not economically viable.

[0011] In other words, although the aforementioned conventional chemical recycling of waste PMMA can yield regenerated MMA through depolymerization, the yield of the produced regenerated MMA is low, and furthermore, since high thermal energy is required in the chemical recycling process, it is not economically viable.

[0012] Furthermore, the aforementioned conventional chemical recycling of waste PMMA has the problem of low yield or selectivity of the generated MMA, and causes environmental pollution resulting from the generation of high thermal energy.

[0013] Therefore, a new technology is needed that solves the problems of the aforementioned conventional chemical recycling process for waste PMMA, offering high economic efficiency and greater environmental friendliness.

[0014] The present disclosure can provide a method for producing recycled MMA from waste PMMA, which has a high recycled MMA yield, because even when waste PMMA is depolymerized at a low temperature, the waste PMMA has a high waste PMMA conversion rate and the waste PMMA depolymerized product produced by depolymerizing waste PMMA has a high recycled MMA (Methylmethacrylate) selectivity.

[0015] The present disclosure provides a method for manufacturing recycled MMA that has a higher MMA yield than conventional methods for obtaining recycled MMA from waste PMMA, and can have excellent economic efficiency and productivity.

[0016] The present disclosure provides a recycled MMA manufacturing apparatus capable of producing recycled MMA from waste PMMA with excellent processability while maintaining a very low temperature for depolymerizing waste PMMA.

[0017] A method for producing regenerated MMA from waste PMMA according to the present disclosure may comprise the steps of depolymerizing waste PMMA at low temperature using a zeolite-based solid acid catalyst and obtaining regenerated MMA from the waste PMMA depolymerized product produced at the step of depolymerizing at low temperature using a plasma catalyst.

[0018] In one embodiment of the present disclosure, the zeolite-based solid acid catalyst may be a hydrogen-type zeolite-based solid acid catalyst substituted with hydrogen ions.

[0019] In one embodiment of the present disclosure, the zeolite-based solid acid catalyst may be prepared by including one or more selected from Y (Faujasite) zeolite, ZSM-5 (Zeolite Socony Mobil-5) zeolite, and MCM-22 (Mobil Composition of Matter-22) zeolite.

[0020] In one embodiment of the present disclosure, the zeolite-based solid acid catalyst may be prepared from MCM (Mobil Composition of Matter) zeolite.

[0021] In one embodiment of the present disclosure, the zeolite-based solid acid catalyst may have a molar ratio of aluminum atoms and silica atoms of 1:1 to 1:50.

[0022] In one embodiment of the present disclosure, the zeolite-based solid acid catalyst may have a molar ratio of aluminum atoms to silica atoms of 1:10 to 1:30.

[0023] In one embodiment of the present disclosure, the low-temperature plasma depolymerization step may be a plasma formed by a dielectric barrier discharge.

[0024] In one embodiment of the present disclosure, the low-temperature plasma depolymerization step may be a depolymerization reaction performed at a temperature of 200 to 500 ℃.

[0025] In one embodiment of the present disclosure, the low-temperature plasma depolymerization step may be a depolymerization reaction performed at a temperature of 200 to 400 ℃.

[0026] In another aspect of the present disclosure, the low-temperature plasma depolymerization step may be a depolymerization reaction performed at a temperature of 250 to 350°C.

[0027] In one embodiment of the present disclosure, the low-temperature plasma depolymerization step may comprise 0.01 to 5 parts by weight of a zeolite-based solid acid catalyst with respect to 100 parts by weight of waste PMMA.

[0028] In one embodiment of the present disclosure, the low-temperature plasma depolymerization step may have a waste PMMA conversion rate of 80% or more calculated by the following Formula 1.

[0029] [Equation 1]

[0030]

[0031] In one embodiment of the present disclosure, the waste PMMA may be waste artificial marble.

[0032] In one embodiment of the present disclosure, the waste PMMA depolymer may contain 40% by weight or more of recycled MMA based on the total weight.

[0033] In one embodiment of the present disclosure, the method for producing recycled MMA from the waste PMMA may have a recycled MMA yield of 35% or more.

[0034] In one embodiment of the present disclosure, the pPMMA depolymer may contain 2,3-butanedione in an amount of 0.1 weight% or less with respect to the total weight.

[0035] According to the present disclosure, a regenerated MMA manufacturing apparatus may produce regenerated MMA by depolymerizing waste PMM with a low-temperature plasma under a zeolite-based solid acid catalyst, and may include a reaction section having a plasma generator disposed therein and a purification section that purifies the product generated in the reaction section to obtain MMA.

[0036] In one embodiment of the present disclosure, the zeolite-based solid acid catalyst may be introduced into the reaction section mixed with waste PMMA.

[0037] In one embodiment of the present disclosure, the zeolite-based solid acid catalyst may be included in one or more catalyst portions disposed within the reaction portion.

[0038] In one embodiment of the present disclosure, the plasma generator may be a dielectric barrier discharge plasma generator.

[0039] In one embodiment of the present disclosure, the method for manufacturing recycled MMA can have superior process economics because, compared to the conventional process for depolymerizing waste PMMA, the temperature required for the process is lower and the process time is shorter.

[0040] In one embodiment of the present disclosure, the method for producing recycled MMA has a waste PMMA conversion rate of 80% or more, 85% or more, or 90% or more when producing a product by depolymerizing waste PMMA, so a large amount of waste PMMA depolymerized product can be produced in a single waste PMMA depolymerization process.

[0041] In one embodiment of the present disclosure, the method for producing recycled MMA may have a recycled MMA content (MMA selectivity) of 40% by weight or more, 45% by weight or more, 50% by weight or more, or 55% by weight or more among the waste PMMA depolymers produced by depolymerizing waste PMMA, so the energy consumption rate for purifying recycled MMA from the waste PMMA depolymers may be low.

[0042] Accordingly, in one embodiment of the present disclosure, the method for producing recycled MMA from waste PMMA has a low temperature for depolymerizing waste PMMA and has the high waste PMMA conversion rate and high MMA selectivity described above, so the yield of the obtained MMA can be 35% or more, 40% or more, 45% or more, or 50% or more.

[0043] Figure 1 shows the XRD measurement results of the hydrogen-type zeolite-based solid acid catalysts prepared in Preparation Examples 1 to 3.

[0044] Figure 2 shows the results measured by the nitrogen adsorption method of the hydrogen-type zeolite-based solid acid catalysts prepared in Preparation Examples 1 to 3.

[0045] Figure 3 shows the pore characteristics results calculated by the nitrogen adsorption method of the hydrogen-type zeolite-based solid acid catalysts prepared in Preparation Examples 1 to 3.

[0046] Figure 4 shows the FT-IR measurement results of pyridine adsorption of hydrogen-type zeolite-based solid acid catalysts prepared in Preparation Examples 1 to 3.

[0047] Figure 5 shows the measurement results of the NH3-temperature desorption program of the hydrogen-type zeolite-based solid acid catalyst prepared in Preparation Example 1.

[0048] Figure 6 shows the measurement results of the NH3-temperature desorption program of the hydrogen-type zeolite-based solid acid catalyst prepared in Preparation Example 2.

[0049] Figure 7 shows the measurement results of the NH3-temperature desorption program of the hydrogen-type zeolite-based solid acid catalyst prepared in Preparation Example 3.

[0050] Unless otherwise defined in this specification, all technical and scientific terms have the same meaning as generally understood by those skilled in the art to which this disclosure pertains.

[0051] The terms used in the description herein are merely for the purpose of effectively describing specific embodiments and are not intended to limit the disclosure.

[0052] The singular form used in this specification is intended to include the plural form unless specifically indicated otherwise in the context.

[0053] Additionally, units used in this specification without special mention are based on weight, for example, the unit of % or ratio is weight %, and temperature means °C unless specifically defined otherwise.

[0054] The numerical ranges used herein include lower and upper limits and all values ​​within the range, increments logically derived from the form and width of the defined range, all of which are limited, and all possible combinations of upper and lower limits of the numerical range defined in different forms. Unless otherwise specifically defined in this specification, values ​​outside the numerical range that may occur due to experimental error or rounding are also included in the defined numerical range.

[0055] Throughout this specification, the terms “comprising,” “having,” “containing,” or “having” any component mean that, unless specifically stated otherwise, other components are not excluded but may be included, and do not exclude elements, materials, or processes not additionally listed.

[0056] In this specification, the term “A nm x B nm” indicating a pore diameter may be a term for indicating a pore shape having an average short diameter of A nm and an average long diameter of B nm, and as an example, an average pore diameter of 0.71 nm x 1.82 nm may mean a pore having an elongated pore shape in which the average short diameter of the pore is 0.71 nm and the average long diameter of the pore is 1.82 nm.

[0057] A method for producing recycled MMA from waste PMMA according to the present disclosure is described below.

[0058] Plastics are rapidly replacing conventional ceramics or metals due to their lightweight nature and high impact resistance. However, these plastics are materials with low biodegradability, and because they do not decompose over long periods, they cause serious environmental pollution.

[0059] In addition, the aforementioned plastics generally have low density and release gases that cause environmental pollution when burned, so there is a problem in that processing them requires a lot of energy and high costs.

[0060] In order to solve the environmental pollution problem caused by the aforementioned waste plastics, biodegradable plastics are being developed by replacing conventional plastics with biodegradable materials (e.g., beeswax, starch, or chitosan) or by modifying conventional plastics to possess biodegradability through the introduction of a biodegradable chemical structure.

[0061] However, since the physical properties of the aforementioned biodegradable materials and biodegradable plastics are inevitably degraded compared to conventionally used plastics, their use is inevitably limited.

[0062] Therefore, waste plastic recycling technology is actively being pursued to process the aforementioned large volume of waste plastic and reduce the production of new plastic, thereby essentially solving the environmental pollution problem caused by waste plastic.

[0063] However, conventional waste plastic recycling inevitably results in a degradation of physical properties compared to new plastics due to reasons such as impurities remaining in the waste plastics and secondary thermal processes. In particular, since the transparency of highly transparent plastics decreases after recycling, the technology is still insufficient to commercialize this.

[0064] Among conventional waste plastics, waste PET has high utility as the product manufactured by depolymerization is recycled ester oil. Since the ester bonds in the structure of waste PET allow for chemical depolymerization more easily, many recycling technologies have already been widely known and are in commercial use.

[0065] Compared to the conventional waste PET recycling technology mentioned above, the conventional waste PMMA recycling technology has limitations in physical recycling because the sorting process of waste PMMA is difficult and the optical and mechanical properties of the manufactured recycled PMMA are degraded due to impurities contained in the waste PMMA. Furthermore, the chemical recycling process for obtaining recycled MMA from the waste PMMA requires a large amount of thermal energy, and the yield of industrially usable compounds is very low, so it remains economically unviable.

[0066] The inventors of the present disclosure, in order to solve the problems associated with the conventional method of manufacturing recycled MMA from waste PMMA, conducted repeated research and discovered a method for manufacturing recycled MMA that can achieve a high yield of recycled MMA while reducing the thermal energy of the process, thereby completing the present disclosure.

[0067] The present disclosure provides a method for producing regenerated MMA from waste PMMA, comprising the steps of: depolymerizing waste PMMA at low temperature using a zeolite-based solid acid catalyst; and obtaining regenerated MMA from the waste PMMA depolymerized product produced at the low temperature plasma depolymerization step.

[0068] The above method for manufacturing recycled MMA involves depolymerizing waste PMMA using a low-temperature plasma under a zeolite-based solid acid catalyst, so the temperature required for the depolymerization process is low, while also enabling a high conversion rate of waste PMMA and high selectivity for recycled MMA.

[0069] Therefore, the above method for manufacturing recycled MMA reduces the time and cost of the process for purifying recycled MMA from the waste PMMA depolymerization described above, and can significantly increase the yield of recycled MMA with a single process, thus offering superior economic efficiency compared to conventional methods for manufacturing recycled MMA from waste PMMA.

[0070] In one embodiment of the present disclosure, the method for producing recycled MMA from waste PMMA may have a temperature of 200°C or higher, 250°C or higher, 300°C or higher, 500°C or lower, 400°C or lower, or 350°C or lower, for example, 200 to 400°C or 250 to 350°C.

[0071] The above method for manufacturing recycled MMA can be preferred because it allows for the depolymerization of waste PMMA at a low temperature plasma under a zeolite-based solid acid catalyst, thereby enabling better processability and economic efficiency.

[0072] In addition, the method for manufacturing the above-mentioned recycled MMA depolymerizes the waste PMMA at a lower temperature compared to the conventional waste PMMA depolymerization process, but can have a waste PMMA conversion rate and high selectivity for recycled MMA of the waste PMMA depolymer, as described later, so the final yield of recycled MMA is high, and thus the processability and economic efficiency of the process for obtaining recycled MMA from the waste PMMA depolymer can also be excellent.

[0073] In one embodiment of the present disclosure, the step of low-temperature plasma depolymerizing the waste PMMA may have a waste PMMA conversion rate calculated by Formula 1 below of 80% or more, 85% or more, 90% or more, 100% or less, less than 100%, or 99% or less. For example, it may be 80 to 99%, 85 to 99%, or 90 to 99%.

[0074] [Equation 1]

[0075]

[0076] At this time, the above waste PMMA conversion rate may be measured when the waste PMMA is depolymerized at 300°C for 2 hours.

[0077] That is, the above method for manufacturing recycled MMA can have a higher waste PMMA conversion rate if waste PMMA is depolymerized at a higher temperature, but even if depolymerization is performed at 300°C, which is lower than the conventional waste PMMA depolymerization temperature, the ratio of waste PMMA being converted into waste PMMA depolymer is high, so it can be preferred as it can depolymerize more than 80% by weight of the input waste PMMA in a single process while shortening the process time.

[0078] In one embodiment of the present disclosure, the method for producing recycled MMA from the waste PMMA may have a content of recycled MMA (recycled MMA selectivity) contained in the waste PMMA depolymerization that is 40 wt% or more, 45 wt% or more, 50 wt% or more, 55 wt%, 60 wt% or more, 80 wt% or less, or 70 wt% or less. For example, it may be 35 to 80 wt%, 40 to 70 wt%, 45 to 70 wt%, 50 to 70 wt%, or 55 to 70 wt%. This is superior to conventional methods in that it has a very high selectivity of recycled MMA.

[0079] The method for producing recycled MMA from the above waste PMMA may be preferred because the generated waste PMMA depolymer may contain recycled MMA within the range described above, thereby reducing the energy required for the purification process to obtain recycled MMA from the generated waste PMMA depolymer, and thus providing superior processability and excellent durability.

[0080] In one embodiment of the present disclosure, the waste PMMA depolymer may contain, in addition to the recycled MMA described above, methanol, methyl isobutyl methacrylate, carbon monoxide (CO), carbon dioxide (CO2), methane (CH4), and other unidentified impurities.

[0081] In addition to recycled MMA, the hydrocarbon gases contained in the above waste PMMA depolymer, such as carbon monoxide, carbon dioxide, and methane, may be utilized as synthesis gas, fuel, and Electrochemical Carbon Control (ECC), but this is merely one example and is not a limitation.

[0082] In one embodiment of the present disclosure, the method of producing recycled MMA from waste PMMA of the present disclosure may include 0.1% by weight or less, 0.05% by weight or less, or not at all, 2,3-butanedione in the waste PMMA depolymer.

[0083] The above waste PMMA depolymerization can be preferred not only because it can have the high regenerated MMA selectivity described above, but also because it can produce trace amounts or none of 2,3-butanedione, which is the cause of odor.

[0084] In one embodiment of the present disclosure, the method for producing recycled MMA from the waste PMMA may have a recycled MMA yield of 35% or more, 40% or more, 45% or more, 50% or more, 70% or less, or 60% or less.

[0085] The yield of the recycled MMA in the above method for producing recycled MMA may be a value obtained from the waste PMMA conversion rate and recycled MMA selectivity described above, and since a very high MMA yield can be obtained by simply depolymerizing the waste PMMA at 300°C for 2 hours with low-temperature plasma, it may be preferred over conventional waste PMMA.

[0086] In other words, the above method for manufacturing recycled MMA can achieve the high waste PMMA conversion rate described above and high selectivity for recycled MMA with only a single depolymerization process at a lower temperature compared to the temperature of the conventional waste PMMA depolymerization process, thereby reducing the energy consumption rate and shortening the time required for the purification process to obtain recycled MMA from the generated waste PMMA depolymer.

[0087] Therefore, since the method for manufacturing recycled MMA from the above-mentioned waste PMMA can have superior economic efficiency and processability compared to conventional methods for manufacturing recycled MMA, it can further increase commercial utilization in the field of waste PMMA chemical recycling technology.

[0088] The following describes in detail a method for manufacturing recycled MMA from the above-mentioned waste PMMA.

[0089] In one embodiment of the present disclosure, a method for producing recycled MMA from waste PMMA may include the step of depolymerizing waste PMMA under a zeolite-based solid acid catalyst using low-temperature plasma.

[0090] In one embodiment of the present disclosure, the waste PMMA may be waste artificial marble, or may be crushed waste artificial marble.

[0091] The above PMMA is widely used in artificial marble due to its high transparency, high colorability, and high weather resistance. Consequently, there is a large amount of waste artificial marble, leading to environmental pollution issues. Additionally, although the above waste artificial marble contains an excessive amount of flame-retardant components such as alumina hydroxide, it has the advantage of being easy to remove, so it may be preferred to obtain recycled MMA using it.

[0092] However, the aforementioned waste artificial marble is preferred merely because it can be crushed without a special process and used as waste PMMA in the low-temperature plasma depolymerization step described above; it does not specifically restrict any material containing PMMA components. As a non-limiting example of waste materials that can be used as the aforementioned waste PMMA, automotive exterior materials, PMMA furniture, automotive headlights, or PMMA sheets may be used.

[0093] In one embodiment of the present disclosure, the waste PMMA may have an average particle size (D50) of 1,000 μm or less, 500 μm or less, 300 μm or less, 200 μm or less, 100 μm or less, 50 μm or less, or 10 μm or more, in terms of having better depolymerization reactivity. For example, it may be ground to 10 to 1000 μm, 10 to 500 μm, 10 to 100 μm, 10 to 70 μm, 20 to 70 μm, or 30 to 70 μm, but is not necessarily limited thereto.

[0094] That is, the above waste PMMA is not specifically limited as long as low-temperature plasma depolymerization is possible, and, for example, it may be used as large particles in the form of pellets.

[0095] In the present disclosure, the waste PMMA used is pre-treated waste PMMA pellets; however, it may be used after removing residual impurities through the grinding process, solid impurity filtering, and residual additive removal described above, but is not necessarily limited to this as long as it possesses the depolymerization reactivity targeted in the present disclosure.

[0096] In one embodiment of the present disclosure, the step of low-temperature plasma depolymerization of the waste PMMA is characterized by using a zeolite-based catalyst, and the zeolite-based solid acid catalyst may be a hydrogen-type zeolite-based solid acid catalyst in which hydrogen ions are substituted.

[0097] The above hydrogen-type zeolite-based solid acid catalyst may refer to a zeolite carrier (porous zeolite) on which hydrogen ions are supported, and since it has strong acidity, it may be preferred as it enables improved depolymerization of waste PMMA.

[0098] In one embodiment of the present disclosure, the zeolite-based solid acid catalyst may be prepared by including any one selected from Y (Faujasite) zeolite, ZSM-5 (Zeolite Socony Mobil-5) zeolite, and MCM-22 (Mobil Composition of Matter-22) zeolite, and in another embodiment, it may be prepared by including MCM-22 zeolite or by using MCM-22 zeolite alone.

[0099] A zeolite-based solid acid catalyst containing a zeolite of the structure described above can increase the depolymerization reactivity of waste PMMA, thereby not only raising the waste PMMA conversion rate but also improving the selectivity of regenerated MMA, which can increase the content of regenerated MMA in the waste PMMA depolymerized product; therefore, it may be preferred, but it is not necessarily a limitation.

[0100] In one embodiment of the present disclosure, the zeolite-based solid acid catalyst may have an average pore diameter measured by nitrogen adsorption of 0.1 to 5.0 nm, 0.2 to 5.0 nm, 0.3 to 3.0 nm, 0.4 to 2.0 nm, 0.4 to 1.0 nm, or 0.4 to 0.8 nm.

[0101] Zeolite-based solid acid catalysts having an average diameter within the above range can have a high surface area, so they may be preferred as catalysts for the waste PMMA depolymerization reaction to reduce the temperature of the depolymerization process and increase the content of regenerated MMA in the waste PMMA depolymer, but this is not necessarily a limitation.

[0102] In addition, the above zeolate-based solid acid catalyst is prepared by including the previously described Y (Faujasite) zeolite, ZSM-5 (Zeolite Socony Mobil-5) zeolite, and MCM-22 (Mobil Composition of Matter-22) zeolite, and thus possesses channel structures with different pore diameters and pore shapes. Furthermore, since it also contains channel structures in which waste PMMA has high activity, it can be preferred as it can achieve superior waste PMMA depolymerization when used as a catalyst for the waste PMMA depolymerization reaction.

[0103] In particular, the zeolite-based solid acid catalyst prepared with the MCM-22 zeolite described above contains pores of different sizes derived from a 12-membered ring supercage and a 10-membered ring channel, so it may be preferred to produce regenerated MMA with higher selectivity and improved depolymerization of spent PMMA even with low thermal energy, but it is not necessarily limited to this.

[0104] In one embodiment of the present disclosure, the zeolite-based solid acid catalyst may have a total acidity point, calculated by adding the Bronstätt acidity point and the Lewis acidity point measured by pyridine adsorption FT-IR, of 300 μmol / g or more, 350 μmol / g or more, 400 μmol / g or more, 450 μmol / g or more, 500 μmol / g or more, 550 μmol / g or more, 600 μmol / g or more, 650 μmol / g or more, or 800 μmol / g or less. For example, it may be 350 to 800 μmol / g, 400 to 800 μmol / g, 500 to 800 μmol / g, or 600 to 800 μmol / g.

[0105] A zeolite-based solid acid catalyst having an acidity point within the above range can be used as a catalyst for the depolymerization reaction of waste PMMA, which can reduce the temperature of the depolymerization process and increase the content of regenerated MMA contained in the waste PMMA depolymer.

[0106] In particular, the step of depolymerizing the waste PMMA using low-temperature plasma can be preferred when depolymerizing the waste PMMA under a zeolite-based solid acid catalyst and low-temperature plasma, as this allows for a lower process temperature, a higher waste PMMA conversion rate, and a higher selectivity for regenerated MMA, thereby providing superior processability and economic efficiency.

[0107] In one embodiment of the present disclosure, the zeolite-based solid acid catalyst may comprise a molar ratio of aluminum atoms to silica atoms of 1:10 to 1:30, 1:10 to 1:25, or 1:10 to 1:20.

[0108] A zeolite-based solid acid catalyst containing silica atoms (Si) and aluminum atoms (Al) in the above molar ratio may be preferred when depolymerizing waste PMMA, as it can achieve a high waste PMMA conversion rate and high MMA selectivity even in a low-temperature depolymerization process.

[0109] In addition, the above-mentioned zeolite-based solid acid catalyst can control the acidity point by controlling aluminum atoms and silica atoms, and can also control the acidity point by substituting alkaline or transition metal elements, so it can be preferred as it allows for easy control of the depolymerization reactivity of waste PMMA containing it.

[0110] In one embodiment of the present disclosure, the step of depolymerizing the waste PMMA with a low-temperature plasma may involve simultaneously introducing the waste PMMA and a zeolite-based solid acid catalyst, or depolymerizing the waste PMMA in a reactor equipped with one or more catalyst layers including a zeolite-based solid acid catalyst.

[0111] In another aspect of the present disclosure, the step of depolymerizing the waste PMMA with a low-temperature plasma may preferably involve simultaneously introducing the waste PMMA and a zeolite-based solid acid catalyst to achieve faster depolymerization and a higher MMA conversion rate, but is not particularly limited as long as the regenerated MMA yield targeted in the present disclosure is achieved.

[0112] In one embodiment of the present disclosure, the step of low-temperature plasma depolymerizing the waste PMMA may comprise 0.1 to 5 parts by weight, 0.1 to 1 part by weight, or 0.1 to 0.5 parts by weight of a zeolite-based solid acid catalyst with respect to 100 parts by weight of the waste PMMA introduced.

[0113] The step of depolymerizing using a zeolite-based solid acid catalyst in a weight portion of the above range may be preferred as it offers excellent economic efficiency by not using an excess amount of catalyst, while also providing excellent depolymerization reactivity and a high regenerated MMA conversion rate, but it is not necessarily limited to this.

[0114] In one embodiment of the present disclosure, the step of depolymerizing the waste PMMA at low temperature plasma may be characterized by using a zeolite-based solid acid catalyst as described above, while simultaneously depolymerizing the waste PMMA under plasma.

[0115] The step of depolymerizing the above-mentioned waste PMMA at low temperature using a zeolite-based solid acid catalyst and depolymerizing the waste PMMA under plasma can be preferred because it significantly increases the waste PMMA conversion rate while increasing the content of regenerated MMA contained in the resulting waste PMMA depolymer, thereby ultimately improving the yield of regenerated MMA.

[0116] In one embodiment of the present disclosure, the step of depolymerizing the waste PMMA with a low-temperature plasma may use a plasma formed by a dielectric barrier discharge.

[0117] The above dielectric barrier discharge plasma may be preferred as it has a lower energy consumption rate compared to other plasma emission methods and can generate plasma even at low temperatures; however, if plasma can be emitted during the depolymerization process of waste PMMA, it is not specifically restricted.

[0118] In one embodiment of the present disclosure, the plasma may be a discharge of one or more inert gases selected from helium, neon, argon, krypton, and xenon, and in another embodiment, helium may be preferred, but is not particularly limited as long as it is possible to introduce the plasma into the reactor.

[0119] Accordingly, the step of depolymerizing the waste PMMA at low temperature plasma results in a high waste PMMA conversion rate and high regenerated MMA selectivity even when depolymerizing the waste PMMA under a zeolite-based solid acid catalyst and low temperature plasma, and through the step of obtaining regenerated MMA described later, a large amount of regenerated MMA can be obtained relative to the input waste PMMA.

[0120] In one aspect of the present disclosure, a method for producing regenerated MMA from waste PMMA may include the step of obtaining regenerated MMA from a waste PMMA depolymerized product produced in the step of depolymerizing the waste PMMA described above at low temperature plasma.

[0121] In one embodiment of the present disclosure, the waste PMMA depolymer is a waste PMMA depolymerized by low-temperature plasma depolymerization, and may be a mixture of gaseous products inside a reactor, and may be cooled by a cooling condenser to primarily separate into a liquid product and a gaseous product that remains in a gaseous state even after cooling by the cooling condenser.

[0122] Subsequently, in order to separate the regenerated MMA contained in the above liquid product, regenerated MMA can be obtained through a distillation process, and various distillation methods such as thin-film distillation, simple distillation, fractional distillation, or vacuum distillation can be utilized without limitation.

[0123] Since there are many already known techniques regarding the above distillation method, a detailed explanation will be omitted.

[0124] In another embodiment, the waste PMMA depolymer can be used to obtain regenerated MMA directly through a distillation process, and there is no particular limitation on the ability to obtain regenerated MMA from the waste PMMA depolymer.

[0125] The present disclosure may provide a regenerated MMA manufacturing apparatus for producing regenerated MMA from waste PMMA under a zeolite-based solid acid catalyst and plasma.

[0126] The above-mentioned regenerated MMA manufacturing apparatus may include a reaction section in which a plasma generator is disposed inside, and a purification section that purifies the product generated in the reaction section to obtain MMA.

[0127] The above-mentioned recycled MMA manufacturing apparatus is equipped with a plasma generator inside the reactor, allowing for the continuous introduction of plasma while the waste PMMA is depolymerized. This not only improves the conversion rate of the waste PMMA but also makes it preferable as it does not generate trace amounts of odor-causing 2,3-butanedione or similar substances.

[0128] In one embodiment of the present disclosure, the zeolite-based solid acid catalyst may be introduced into the reaction section mixed with waste PMMA, and in another embodiment, one or more catalyst sections containing the zeolite-based solid acid catalyst may be disposed inside the reaction section.

[0129] The above-described regenerated MMA manufacturing apparatus may have a zeolite-based solid acid catalyst introduced or a catalyst section containing the same disposed inside the reaction section, so that the regenerated MMA may contain a high content of waste PMMA depolymer.

[0130] The method for manufacturing recycled MMA from the waste PMMA is described in more detail through the following examples. However, the following examples are merely references for the detailed explanation of the present disclosure and the present invention is not limited thereto and may be implemented in various forms. Furthermore, unless otherwise defined, all technical and scientific terms have the same meaning as generally understood by one of the art to which the present disclosure belongs. Additionally, the terms used in the description of the present disclosure are merely for the purpose of effectively describing specific embodiments and are not intended to limit the present disclosure.

[0131] Preparation of zeolite-based solid acid catalysts

[0132] [Preparation Example 1]

[0133] (MCM-22 Zeolite Manufacturing)

[0134] Sodium hydroxide, sodium aluminate (containing 53% Al2O3), hexamethyleneimine (HMI), and fumed silica were added to deionized water and stirred at room temperature for 12 hours to prepare a solution. At this time, the solution was Si4 + , Al3 + , Na + , HMI and H2O were included in a molar ratio of 1:0.066:0.24:0.50:59.6.

[0135] Subsequently, the above solution was used to synthesize an MCM-22 (Mobil Composition of Matter-22) zeolite precursor by hydrothermal synthesis at 150°C for 9 days in a 40 ml stainless-steel autoclave with a Teflon liner. Afterward, the autoclave was cooled with cooling water, and the MCM-22 zeolite precursor was washed sequentially with deionizing water and ethanol, and then centrifuged. Subsequently, the washed MCM-22 zeolite precursor was dried at 70°C for 8 hours, and then calcined at 580°C for 12 hours under aeration to produce the MCM-22 zeolite.

[0136] (Manufacturing of hydrogen-type zeolite)

[0137] 1 g of the above MCM-22 zeolite was added to a 1 M NH4NO3 solution and stirred at room temperature for 3 hours to carry out an ion exchange reaction, thereby synthesizing an NH4-ion-exchanged MCM-22 zeolite, and then dried at 70 ℃ for 8 hours. Subsequently, the obtained NH4-ion-exchanged MCM-22 zeolite was calcined under aeration at 550 ℃ for 6 hours to obtain a hydrogen-type MCM-22 zeolite solid acid catalyst (HMCM-22) with hydrogen ions substituted.

[0138] [Preparation Example 2]

[0139] A hydrogen-type Y zeolite solid acid catalyst (HY) was obtained by performing the same procedure as in Preparation Example 1 above, except that Y zeolite (Thermo Fisher Scientific) was used instead of MCM-22 zeolite.

[0140] [Preparation Example 3]

[0141] A hydrogen-type ZSM-5 zeolite solid acid catalyst (HZSM-5) was obtained by performing the same procedure as in Preparation Example 1 above, except that ZSM-5 zeolite (Zeolyst) was used instead of MCM-22 zeolite.

[0142] Experimental Example 1: X-ray diffraction (XRD) analysis

[0143] The catalysts prepared in Preparation Examples 1 to 3 above were measured using an X-ray diffractometer (Rigaku, Miniflex 600), and X-rays of CuKα (λ = 0.154 nm, 40 kV, 40 mA) were measured at a measurement angle of 5 to 50°, and the results are shown in Fig. 1 below.

[0144] Experimental Example 2: Analysis of Nitrogen Physical Adsorption

[0145] The catalysts prepared in Preparation Examples 1 to 3 above were degassed at 300 °C for 12 hours, and then measured at 77 °C using an adsorption analyzer (Micromeritics, ASAP 2020). The results are shown in Fig. 2 below. The results of the nitrogen physical adsorption analysis were used to calculate the micropore size distribution using the Horvath-Kawazoe (HK) method, and the results are shown in Fig. 3 below.

[0146] As shown in Figure 1 below, it was confirmed that the MCM-22 zeolite solid acid catalyst (HMCM-22) prepared in Preparation Example 1 has a MWW crystal structure, the hydrogen-type Y zeolite solid acid catalyst (HY) prepared in Preparation Example 2 has a FUA crystal structure, and the hydrogen-type ZSM-5 zeolite solid acid catalyst (HZSM-5) prepared in Preparation Example 3 has an MFI crystallization structure.

[0147] As shown in Figure 2 below, it was confirmed that the hydrogen-type zeolite-based solid acid catalysts prepared in Preparation Examples 1 to 3 above have results similar to the adsorption isotherm type 1 overall, and that they have pores capable of further enhancing the depolymerization of waste PMMA.

[0148] In addition, it was confirmed that the MCM-22 zeolite solid acid catalyst (HMCM-22) prepared in Manufacturing 1 above exhibits slight hysteresis in the P / P0 > 0.8 range, and thus has a high surface area and various pore sizes, which can be further enhanced as a catalyst.

[0149] By looking at Fig. 3 below, the respective pore characteristics of the hydrogenation zeolite-based solid acid catalysts prepared in Preparation Examples 1 to 3 can be observed more closely.

[0150] It was confirmed that the HMCM-22 prepared in Preparation Example 1 above contains pores with an average pore diameter of 0.71 nm x 1.82 nm derived from a 12-Membered Ring Supercage (12-MR Supercage) and pores with an average pore diameter of 0.41 nm x 0.51 nm or 0.40 nm x 0.55 nm derived from a 10-Membered Ring Channel (10-MR Shaped Plate Channel).

[0151] In addition, it was confirmed that the HY prepared in Preparation Example 2 above has an average pore diameter of 0.74 nm x 0.74 nm derived from a 12-membered ring (MR), and the HZSM-5 prepared in Preparation Example 3 above has a median pore width of 0.49 nm and contains pores with a pore diameter of 0.51 nm x 0.55 nm derived from a 10-membered ring channel (10-MR) and pores with an average pore diameter of 0.53 nm x 0.56 nm derived from a 10-MR linear channel.

[0152] Accordingly, since the hydrogen-type zeolite-based solid acid catalyst prepared in Preparation Examples 1 to 3 above has the unique pore structure described above, a waste PMMA depolymer with high regenerated MMA selectivity can be produced by the depolymerization reaction of waste PMMA containing it, and in particular, it can be expected that HMCM-22 prepared in Preparation Example 1 above can have even improved regenerated MMA selectivity.

[0153] Furthermore, the above-mentioned zeolite-based solid acid catalyst exhibits excellent stability in high-temperature environments and maintains its crystal structure and acidity well, thereby enabling an excellent catalyst lifespan. Additionally, since the acidity point of the above-mentioned zeolite-based solid acid catalyst can be controlled by adjusting the content of aluminum atoms, silica atoms, other alkali metals, and other transition metals, the depolymerization of waste PMMA can be easily controlled.

[0154] Experimental Example 3: Fourier Transform Infrared Spectroscopy (FT-IR) Measurement of Pyridine Adsorbed

[0155] 30 mg of the catalyst prepared in Preparation Examples 1 to 3 above was pelletized into a 6.5 mm disc shape, placed in a commercial high-temperature shell (Harrick Scientific), and sealed using a CaF2 window. Subsequently, the high-temperature shell was heated to 450 °C for 2 hours, then cooled to 150 °C and pyridine was adsorbed for 30 minutes. Afterward, at 150 °C, the sample was measured using a Fourier Transform Infrared (FT-IR) spectrometer (Thermo Fisher Scientific, Thermo Nicolet iS50) while physically desorbing the adsorbed pyridine. The measured spectrum is shown in Figure 4 below. The Lewis acidity point (LAS) and Brønsted acidity point (BAS) were determined from extinction coefficients of 1.73 and 1.23 cm / umol, respectively, and are shown in Figure 4 and Table 1 below.

[0156] Experimental Example 4: Measurement of NH3-temperature programmed desorption (NH3-TPD)

[0157] The catalysts prepared in Preparation Examples 1 to 3 above were activated by heating at 500°C for 1 hour, then cooled to 25°C, and adsorbed NH3 for 30 minutes in a mixed gas of 50 SCCM mixed with NH33 mol%. The catalysts with adsorbed NH3 were heated to 800°C at a heating rate of 10°C / min in a He gas stream, and the acidity of the catalyst was measured using a catalyst characteristic measuring instrument (Microtrac BEL, BEL-CAT). Subsequently, the catalysts of Preparation Examples 1 to 3 were measured using the above measurement method. The measurement results of the catalyst prepared in Preparation Example 1 are shown in Fig. 5 below, the measurement results of the catalyst prepared in Preparation Example 2 are shown in Fig. 6 below, and the measurement results of the catalyst prepared in Preparation Example 3 are shown in Fig. 7 below.

[0158] Brønsted Acidity (μmol / g) Lewis Acidity (μmol / g) Total Acidity (μmol / g) Preparation Example 1 600.080.3680.3 Preparation Example 2 234.092.1326.1 Preparation Example 3 329.096.7425.7

[0159] As confirmed by Figure 4 below and Table 1 above, the hydrogen-type zeolite-based solid acid catalysts prepared in Preparation Examples 1 to 3 have a Brosted acidity point of 200.0 μmol / g or higher and a Lewis acidity point of 80.0 μmol / g or higher, so it can be confirmed that all of them can improve the depolymerization of waste PMMA.

[0160] In addition, by referring to FIGS. 5 to 7 below, it can be confirmed that the hydrogen-type zeolite-based solid acid catalysts prepared in Preparation Examples 1 to 3 have a weak acidic effect at 170 to 220 ℃ and a strong Bronsted acidity at 280 to 550 ℃.

[0161] Therefore, the depolymerization process of waste PMMA using the hydrogen-type zeolite-based solid acid catalyst prepared in Preparation Examples 1 to 3 above can reduce the process temperature because the acidity of the catalyst can be activated even at a lower temperature.

[0162] Manufacture of a batch reactor equipped with a plasma generator

[0163] [Preparation Example 4]

[0164] A cylindrical α-Al2O3 tube with an outer diameter of 10 mm and a thickness of 2 mm was used as a fluid barrier inside a batch reactor, and a stainless steel mesh with a length of 150 mm was wrapped around the outer wall of the α-Al2O3 tube to form a ground electrode. Subsequently, a power electrode (stainless steel, diameter 3 mm) was placed in the center of the cylindrical α-Al2O3 tube to manufacture a plasma generator.

[0165] The power electrode was connected to a transformer (0-20kV, 1000Hz) to provide a sinusoidal AC power supply (0-220V, 60-1,000Hz), and the energy level for the plasma-assisted reaction was fixed at 10 kV and 1 kHz. The voltage was monitored using a high-voltage probe (1000:1, P6015A, Tektronix) and adjusted to an appropriate level. Additionally, a 1μF capacitor was connected in series after the ground electrode to measure the charge transferred from the plasma, and the voltage on both sides of the capacitor could be monitored using a voltage probe (10:1 P6100; Tektronix).

[0166] Afterwards, an ice water bath was placed at the outlet of the batch reactor equipped with the plasma generator to cool the discharged gas, and the outlet was connected so that the uncooled gas could be discharged.

[0167] Manufacture of recycled MMA from waste PMMA

[0168] [Example 1]

[0169] Waste PMMA pellets (LXMMA) manufactured from waste artificial marble were ground at 3,500 rpm for 30 seconds using a grinder (AccuResearch, WC-3L), and then filtered through a stainless-steel mesh to prepare ground waste PMMA with an average particle size (D50) of 53 μm or more. As a result of TG / DTA analysis of the ground waste PMMA, it was confirmed that the mixture consisted of 43 wt% PMMA, 356 wt% Al(OH) and 1 wt% unidentified impurities.

[0170] Subsequently, 100 parts by weight of the crushed waste PMMA were introduced into a batch reactor equipped with a plasma generator prepared in Preparation Example 4, and 0.4 parts by weight of the MCM-22 zeolite solid acid catalyst (HMCM-22) prepared in Preparation Example 1 were introduced with respect to 100 parts by weight of the waste PMMA. Subsequently, helium gas was introduced into the batch reactor as a plasma discharge material at a flow rate of 10 sccm, and the depolymerization reaction of the waste PMMA was carried out at 300°C for 2 hours.

[0171] During the above depolymerization reaction, the generated gaseous products were discharged and cooled in an ice bath to obtain a liquid product and uncooled gaseous products.

[0172] [Example 2]

[0173] In the above Example 1, the depolymerization reaction of waste PMMA was carried out in the same manner, except that HY prepared in Example 2 was used instead of HMCM-22 prepared in Example 1.

[0174] During the above depolymerization reaction, the generated gaseous products were discharged and cooled in an ice bath to obtain a liquid product and uncooled gaseous products.

[0175] [Example 3]

[0176] In the above Example 1, the depolymerization reaction of waste PMMA was carried out in the same manner, except that HZSM-5 prepared in Example 3 was used instead of HMCM-22 prepared in Example 1 prepared in Example 1 prepared in the same manner.

[0177] During the above depolymerization reaction, the generated gaseous products were discharged and cooled in an ice bath to obtain a liquid product and uncooled gaseous products.

[0178] [Comparative Example 1]

[0179] In the above Example 1, the depolymerization reaction of waste PMMA was carried out in the same manner, except that the plasma generator was not operated and the HMCM-22 prepared in Preparation Example 1 was not introduced.

[0180] During the above depolymerization reaction, the generated gaseous products were discharged and cooled in an ice bath to obtain a liquid product and uncooled gaseous products.

[0181] [Comparative Example 2]

[0182] In the above Example 1, the depolymerization reaction of waste PMMA was carried out in the same manner except that HMCM-22 prepared in Preparation Example 1 was not added.

[0183] During the above depolymerization process, the generated gaseous products were discharged and cooled in an ice bath to obtain a liquid product and uncooled gaseous products.

[0184] [Comparative Example 3]

[0185] In the above Example 1, the depolymerization reaction of waste PMMA was carried out in the same manner except that the plasma generator was not operated.

[0186] During the above depolymerization reaction, the generated gaseous products were discharged and cooled in an ice bath to obtain a liquid product and uncooled gaseous products.

[0187] Experimental Example 5: Liquid Product Analysis

[0188] In the above examples and comparisons, the liquid product generated by cooling in an ice water bath was measured using a gas chromatograph (Agilent 8890) equipped with a Stabilwax-MS column, and the liquid product was quantitatively analyzed using a selective ion monitoring (SIM) method with 1-butanol as the internal standard and 1-pentanol as the solvent, and is shown in Table 3 below.

[0189] Experimental Example 6: Analysis of Gaseous Products

[0190] The gaseous products generated in the above examples and comparative examples were separated using Carboxen 1000 (Agilent Technology) and GS-GasPro (Agilent Technology) columns in a gas chromatograph (Young Lin Instrument, 6500 GC), and then the gaseous products were quantitatively analyzed using a thermal conductivity detector (TCD) and an ionization detector (FID) and are shown in Table 3 below.

[0191] Hydrogen-type zeolite-based solid acid catalyst Plasma Treatment Type Structure Al and Si Molar Ratio ○ Example 1 Preparation Example 1 MCM-221:15 ○ Example 2 Preparation Example 2 Y1:15 ○ Example 3 Preparation Example 3 ZSM-51:15 ○ Comparative Example 1 No catalyst added X Comparative Example 2 No catalyst added ○ Comparative Example 3 Preparation Example 1 MCM-221:15 X

[0192] Example Comparative Example 1 2 3 1 2 3 PMMA Conversion Rate (%) 90.9 90.7 89.1 50.9 90.6 52.6 MMA Yield (%) 50.0 939.5 540.9 917.3 634.6 26.2 Liquid Product MMA (Weight%) 58.4 43.6 46.0 34.1 38.2 50.6 MeOH (Weight%) 3.9 612.3 11.1 33.5 10.3 24.9 MAA (Weight%) 2.8 81.5 12.0 30.2 80.6 70.2 7 MIB (Weight%) 0.8 71.2 30.7 40.0 41.2 70.0 3 Total Amount (Weight%) 66.4 59.7 60.7 68.0 51.2 75.8 Gaseous Product CO8.887.638.812.867.212.74 CO28.067.3811.13.366.603.22 C40.67.73.740.300.690.29 C20.85.89.890.290.960.28 C31.121.121.160.501.150.48 C40.47.62.560.150.490.15 C52.102.252.263.112.422.98 Total (Weight%) 22.22.22.624.710.619.510.1 Unidentified Impurities (Weight%) 11.72.0.717.521.530.114.0

[0193] Looking at the recycled MMA manufacturing methods of Examples 1 to 3 above, it was confirmed that not only can the waste PMMA conversion rate be 80% or more, 85% or more, or 90% or more, but the recycled MMA content contained in the waste PMMA depolymer is 40% by weight or more, and that there is a very high selectivity for recycled MMA.

[0194] Accordingly, the method for producing recycled MMA according to Examples 1 to 3 above has an excellent recycled MMA yield of 35% or more, preferably 40% or more, and even more preferably 50% or more, so the processability and economic efficiency of obtaining recycled MMA by purifying waste PMMA in the future can be very excellent.

[0195] In contrast, as shown in Table 3 above, the recycled MMA manufacturing methods of Comparative Examples 1 to 3 have low recycled MMA selectivity, and if not plasma treated, the waste PMMA conversion rate is also very low, so it was confirmed that they have a lower recycled MMA yield compared to Examples 1 to 3.

[0196] Although embodiments of the present disclosure have been described above, the present invention is not limited to the above embodiments and can be manufactured in various different forms, and those skilled in the art will understand that it can be implemented in other specific forms without changing the technical concept or essential features of the present disclosure. Therefore, the embodiments described above should be understood as illustrative in all respects and not limited to one.

Claims

1. A step of low-temperature plasma depolymerization of waste PMMA under a zeolite-based solid acid catalyst; and A method for producing regenerated MMA from waste PMMA, comprising the step of obtaining regenerated MMA from the waste PMMA depolymerized product generated in the above low-temperature plasma depolymerization step.

2. Regarding Paragraph 1, The above zeolite-based solid acid catalyst is a hydrogen-type zeolite-based solid acid catalyst, and the method for producing regenerated MMA from waste PMMA is a hydrogen-type zeolite-based solid acid catalyst.

3. Regarding Paragraph 1, A method for producing recycled MMA from waste PMMA, wherein the zeolite-based solid acid catalyst comprises one or more selected from Y(Faujasite) zeolite, ZSM-5 (Zeolite Socony Mobil-5) zeolite, and MCM-22 (Mobil Composition of Matter-22) zeolite.

4. Regarding Paragraph 3, A method for producing recycled MMA from waste PMMA, wherein the above-mentioned zeolite-based solid acid catalyst is manufactured from MCM (Mobil Composition of Matter) zeolite.

5. With respect to Paragraph 1, The above zeolite-based solid acid catalyst is a method for producing recycled MMA from waste PMMA in which the molar ratio of aluminum atoms to silica atoms is 1:1 to 1:

50.

6. Regarding Paragraph 5, The above zeolite-based solid acid catalyst is a method for producing recycled MMA from waste PMMA in which the molar ratio of aluminum atoms to silica atoms is 1:10 to 1:

30.

7. With respect to Paragraph 1, A method for producing recycled MMA from waste PMMA, wherein the above low-temperature plasma depolymerization step uses plasma formed by dielectric barrier discharge.

8. With respect to Paragraph 1, A method for producing recycled MMA from waste PMMA, wherein the low-temperature plasma depolymerization step described above is a depolymerization reaction carried out at a temperature of 200 to 500 ℃.

9. With respect to Paragraph 1, A method for producing recycled MMA from waste PMMA, wherein the low-temperature plasma depolymerization step described above is a depolymerization reaction carried out at a temperature of 200 to 400 ℃.

10. With respect to Paragraph 1, A method for producing recycled MMA from waste PMMA, wherein the low-temperature plasma depolymerization step described above is a depolymerization reaction carried out at a temperature of 250 to 350 ℃.

11. With respect to Paragraph 1, A method for producing recycled MMA from waste PMMA, wherein the low-temperature plasma depolymerization step comprises 0.01 to 5 parts by weight of a zeolite-based solid acid catalyst per 100 parts by weight of waste PMMA.

12. With respect to Paragraph 1, The above low-temperature plasma depolymerization step is a method for producing recycled MMA from waste PMMA with a waste PMMA conversion rate of 80% or more calculated by the following Formula 1. [Equation 1] 13. With respect to Paragraph 1, The above waste PMMA is a method for manufacturing recycled MMA from waste PMMA, which is waste artificial marble.

14. In Paragraph 1, A method for producing recycled MMA from waste PMMA, wherein the above waste PMMA depolymer contains at least 40% by weight of recycled MMA based on the total weight.

15. In Paragraph 1, The above method for producing recycled MMA from waste PMMA is a method for producing recycled MMA from waste PMMA with a recycled MMA yield of 35% or more.

16. In Paragraph 1, A method for producing recycled MMA from waste PMMA, wherein the above waste PMMA depolymer contains 0.1% by weight or less of 2,3-butanedione based on the total weight.

17. A regenerated MMA manufacturing apparatus for producing regenerated MMA by low-temperature plasma depolymerization of waste PMM under a zeolite-based solid acid catalyst, The above-mentioned regenerated MMA manufacturing apparatus comprises a reaction section having a plasma generator disposed therein; and A regenerated MMA manufacturing apparatus comprising: a purification unit for purifying the product generated in the above reaction unit to obtain MMA.

18. With respect to Paragraph 17, A regenerated MMA manufacturing apparatus in which the above-mentioned zeolite-based solid acid catalyst is mixed with waste PMMA and introduced into the reaction section.

19. With respect to Paragraph 17, A regenerated MMA manufacturing apparatus in which the above-mentioned zeolite-based solid acid catalyst is included in one or more catalyst sections arranged inside the reaction section.

20. Regarding Paragraph 17, The above plasma generator is a regenerative MMA manufacturing device that is a dielectric barrier discharge plasma generator.

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