Method for manufacturing composite heat storage element

Abstract

A method for manufacturing a composite heat storage element according to embodiments of the present invention comprises the steps of: pulverizing an alumina-based waste catalyst to prepare a powder having a particle size (D90) of 30 µm or more and less than 150 µm; heat-treating the powder; mixing the heat-treated powder with an alumina-based binder to prepare a first mixed solution; mixing the first mixed solution, a solvent, and an acidic solution to prepare a second mixed solution; extrusion-molding the mixed solution to prepare a preliminary composite heat storage element; and drying and firing the preliminary composite heat storage element.

Description

Method for manufacturing composite heat storage material

[0001] The present invention relates to a method for manufacturing a composite heat storage body.

[0002] The hazardous waste gases emitted from semiconductor manufacturing processes are extremely diverse, and most are highly volatile and contain substances that are harmful to humans or have high global warming potentials. In particular, perfluorinated compounds (PFCs), emitted during etching and deposition processes, are highly stable and difficult to remove. Because of their high global warming potential and long decomposition times, PFCs accumulate in the atmosphere, and their emissions from semiconductor manufacturing processes are increasing annually. Consequently, regulations on PFCs are being strengthened worldwide.

[0003] To date, no alternative gas has been developed that is more efficient and offers better product quality than carbon tetrafluoride (CF4), which is used in silicon substrate etching, and CF4 is still used in semiconductor processes.

[0004] Catalytic decomposition is a technology for decomposing perfluorinated compounds. The catalysts used in this process require the reaction to be performed in a high-temperature reactor at temperatures exceeding 700°C, which can incur significant continuous operating costs and lead to significant energy consumption. Furthermore, the use of specific metals or compounds to manufacture the catalysts can increase costs.

[0005] Catalytic decomposition is a technology that can decompose difficult-to-decompose PFCs at low temperatures below 800℃ using a catalyst and steam. Conventional devices for decomposing hazardous gases such as perfluorinated compounds are configured to accommodate a heat accumulator and catalyst within a chamber, and supply hazardous gases into the chamber for decomposition. However, the catalyst used to stably remove hazardous gases must be replaced periodically, which results in the generation and disposal of spent catalyst. If catalyst replacement is not performed periodically, the efficiency of removing hazardous gases decreases.

[0006] Accordingly, there is a need to develop a composite accumulator that can solve the problem of waste catalyst generation, stably remove harmful gases, and improve the lifespan of catalysts and devices.

[0007] One object of the present invention is to provide a method for manufacturing a composite heat storage body capable of effectively decomposing a perfluorinated compound and having excellent heat storage performance.

[0008] A method for manufacturing a composite heat accumulator according to embodiments of the present invention comprises the steps of: pulverizing an alumina-based waste catalyst to manufacture a powder having a particle size (D90) of 30 ㎛ or more and less than 150 ㎛; heat-treating the powder; mixing an alumina-based binder with the heat-treated powder to manufacture a first mixed solution; mixing the first mixed solution, a solvent, and an acidic solution to manufacture a second mixed solution; extruding the mixed solution to manufacture a preliminary composite heat accumulator; and drying and sintering the preliminary composite heat accumulator.

[0009] According to exemplary embodiments, the number of channels per square inch (CPSI) of the composite thermal accumulator may be from 30 to 70.

[0010] According to exemplary embodiments, the content of the alumina-based waste catalyst relative to the total weight of the first mixed solution may be 50 wt% to 95 wt%.

[0011] According to exemplary embodiments, the content of the alumina-based binder relative to the total weight of the first mixed solution may be 30 wt% or less.

[0012] According to exemplary embodiments, the alumina-based binder may include at least one selected from the group consisting of alpha alumina (α-Al2O3), beta alumina (β-Al2O3), gamma alumina (γ-Al2O3), delta alumina (δ-Al2O3), theta alumina (θ-Al2O3), kappa alumina (κ-Al2O3), and boehmite.

[0013] According to exemplary embodiments, the first mixed solution may further comprise an auxiliary additive.

[0014] According to exemplary embodiments, the content of the auxiliary additive relative to the total weight of the first mixed solution may be 30 wt% or less.

[0015] According to exemplary embodiments, the auxiliary additive is a compound containing tungsten, a compound containing lanthanum, silica, zeolite, cordierite, mullite, silica-alumina, titania, magnesia, Fe2O3 / TiO2, Fe2O3 / Al2O3, MgO / TiO2, ZrO2 / Al2O3, ZrO x / It may include at least one selected from the group consisting of TiO2, CeO2 / TiO2, CeO2 / ZrO2, and V2O5 / TiO2.

[0016] According to exemplary embodiments, in the step of heat treating the powder, the heat treatment temperature may be 200°C or higher.

[0017] According to exemplary embodiments, in the step of drying and firing the preliminary composite accumulator, the firing temperature may be 600°C or higher.

[0018] Composite accumulators manufactured using the methods for manufacturing composite accumulators according to embodiments of the present invention exhibit high decomposition efficiency of perfluorinated compounds and possess superior heat capacity and strength. Furthermore, they offer economic and environmental benefits by recycling waste catalysts into composite accumulators.

[0019] When the above composite accumulator is applied to a harmful gas removal device, the perfluorinated compound removal performance can be added to the accumulator, thereby improving the catalyst life and removal performance stability of the harmful gas removal device, and by recovering heat, the energy required to maintain the temperature can be reduced.

[0020] Figure 1 schematically illustrates a flow chart of a method for manufacturing a composite accumulator according to exemplary embodiments.

[0021] Figures 2 and 3 are schematic diagrams showing a honeycomb-shaped structure of a composite accumulator according to exemplary embodiments.

[0022] FIG. 4 is a schematic diagram illustrating a reactor including a composite accumulator assembly according to exemplary embodiments.

[0023] Figure 5 is a photograph showing the results of evaluating the shape stability of a composite accumulator according to exemplary embodiments.

[0024] Figure 6 is a photograph showing the results of evaluating the shape stability of a composite heat storage body according to Comparative Example 2.

[0025] Figure 7 is a photograph showing the results of evaluating the shape stability of a composite accumulator according to Comparative Example 1.

[0026] Hereinafter, the present disclosure will be described in detail with reference to the attached drawings. However, these are merely exemplary and the present disclosure is not limited to the specific embodiments described as examples.

[0027] Exemplary embodiments of the present disclosure provide a method for manufacturing a composite heat accumulator, comprising the steps of: pulverizing an alumina-based waste catalyst to produce a powder having a particle size (D90) of 30 ㎛ or more and less than 150 ㎛; heat-treating the powder; mixing an alumina-based binder with the heat-treated powder to produce a first mixed solution; mixing the first mixed solution, a solvent, and an acidic solution to produce a second mixed solution; extruding the mixed solution to produce a preliminary composite heat accumulator; and drying and sintering the preliminary composite heat accumulator.

[0028] The above "alumina-based waste catalyst" may refer to a catalyst that has been used in a subsequent process during a semiconductor manufacturing process and then exported. Specifically, the alumina-based waste catalyst may refer to a catalyst used for the purpose of removing perfluorinated compounds generated during semiconductor manufacturing processes such as memory or LCD.

[0029] As examples of the above perfluorinated compounds, CF4, C2F6, C3F8, C4F 10 Completely perfluorinated compounds such as CHF3, CH2F2, C2HF5, C3HF7, C4HF9; incompletely perfluorinated compounds such as perfluorooctanoic acid, perfluorosulfonic acid, perfluorobutanoic acid, perfluorononanoic acid, etc. For example, the perfluorinated compounds may include compounds generated from etchants in an etching process during a semiconductor manufacturing process or reactor cleaning agents in a chemical vapor deposition process. In one embodiment, the perfluorinated compounds may include CF4.

[0030] The method for manufacturing the above composite thermal accumulator is economical because it reduces raw material costs by applying the alumina-based waste catalyst, and it minimizes negative environmental impacts such as reducing waste generation and increasing greenhouse gas reduction efficiency. Furthermore, by applying an alumina-based material as the waste catalyst, it can achieve high thermal stability and heat transfer efficiency.

[0031] While existing catalysts for decomposing perfluorinated compounds do not have a heat storage function, the composite heat storage body manufactured by the method for manufacturing the composite heat storage body of exemplary embodiments according to the present disclosure has a catalytic function with high efficiency in decomposing perfluorinated compounds, and can also have a heat storage function in an RCS (Regenerative Catalytic System) system.

[0032] Compared to the decomposition of perfluorinated compounds using a catalyst, which requires the reaction to be performed in a reactor at a temperature of 700°C or higher, which incurs continuous operating costs, the operating costs required to maintain the reactor temperature can be significantly reduced by recovering heat through the heat storage performance of the composite heat storage body manufactured by the method for manufacturing the composite heat storage body of the exemplary embodiments according to the present disclosure.

[0033] In addition, the composite accumulator manufactured by the method for manufacturing the composite accumulator of the exemplary embodiments according to the present disclosure has excellent perfluorinated compound decomposition efficiency performance, thereby helping to improve the catalyst life and increasing the stability of perfluorinated compound decomposition within the device.

[0034] In one embodiment, in the step of pulverizing the alumina-based waste catalyst to produce a powder having a particle size (D90) of 30 ㎛ or more and less than 150 ㎛, the pulverization may be performed using a pin mill, a ball mill, a jet mill, or a hammer mill. As long as the alumina-based waste catalyst can be pulverized to produce a powder having a particle size (D90) of 30 ㎛ or more and less than 150 ㎛, the pulverization conditions may not be particularly limited.

[0035] In one embodiment, the particle size (D90) may be 30 μm or more, 40 μm or more, 50 μm or more, or less than 150 μm, 145 μm or less, 140 μm or less, 130 μm or less, 120 μm or less, 110 μm or less, or 100 μm or less.

[0036] When the particle size (D90) of the above powder satisfies the above-mentioned range, the shape stability of the composite heat storage body can be maintained and surface cracking can be minimized.

[0037] In one embodiment, in the step of heat-treating the powder, the heat treatment temperature may be 200°C or higher.

[0038] For example, the heat treatment temperature may be 200°C.

[0039] When the heat treatment temperature satisfies the above-mentioned range, the reactivity and efficiency of the powder can be improved.

[0040] In one embodiment, the heat treatment time of the step of heat treating the powder may be 4 hours or more. For example, it may be 4 hours.

[0041] When the heat treatment time satisfies the above-mentioned range, the reactivity and efficiency of the powder can be improved.

[0042] In one embodiment, the content of the alumina-based waste catalyst relative to the total weight of the first mixed solution may be 50 wt% to 95 wt%.

[0043] For example, the content of the alumina-based waste catalyst relative to the total weight of the first mixed solution may be 55 wt% to 90 wt% or 60 wt% to 90 wt%.

[0044] When the content of the alumina-based waste catalyst satisfies the above-mentioned range, the strength of the composite heat accumulator can be improved, and the decomposition performance of the composite heat accumulator for perfluorinated compounds can be improved. For example, when the content of the alumina-based waste catalyst is less than 50 wt%, the content of the active material capable of decomposing perfluorinated compounds per unit area decreases, and thus the decomposition performance of the composite heat accumulator for perfluorinated compounds may deteriorate. For example, when the content of the alumina-based waste catalyst exceeds 90 wt%, the content of the active material per unit area increases, and thus the decomposition performance of perfluorinated compounds may increase, but the bonding force between raw materials may be weak, and thus the strength of the composite heat accumulator may be reduced.

[0045] In one embodiment, the content of the alumina-based binder relative to the total weight of the first mixed solution may be 30 wt% or less.

[0046] In one embodiment, the content of the alumina-based binder relative to the total weight of the first mixed solution may be 5 wt% or more, 10 wt% or more, or 20 wt% or more.

[0047] When the content of the alumina-based binder satisfies the above-mentioned range, the strength of the composite heat storage body can be improved, and the heat capacity can be improved by improving the density of the composite heat storage body.

[0048] In one embodiment, the alumina-based binder may include at least one selected from the group consisting of alpha alumina (α-Al2O3), beta alumina (β-Al2O3), gamma alumina (γ-Al2O3), delta alumina (δ-Al2O3), theta alumina (θ-Al2O3), kappa alumina (κ-Al2O3), and boehmite.

[0049] In one embodiment, the alumina-based binder may include two or more alumina-based compounds having different crystal structures.

[0050] In one embodiment, the alumina-based binder may include at least one of alpha alumina (α-Al2O3) and gamma alumina (γ-Al2O3).

[0051] In one embodiment, the alumina-based binder may include alpha alumina (α-Al2O3) and gamma alumina (γ-Al2O3).

[0052] In one embodiment, the alumina-based binder may include alpha alumina (α-Al2O3).

[0053] In one embodiment, the first mixed solution may further comprise an auxiliary additive.

[0054] For example, the auxiliary additives include compounds containing tungsten, compounds containing lanthanum, silica, zeolite, cordierite, mullite, silica-alumina, titania, magnesia, Fe2O3 / TiO2, Fe2O3 / Al2O3, MgO / TiO2, ZrO2 / Al2O3, ZrO x / It may include at least one selected from the group consisting of TiO2, CeO2 / TiO2, CeO2 / ZrO2, and V2O5 / TiO2.

[0055] For example, the compound containing tungsten may be W2O3, and the compound containing lanthanum may be La2O3, but is not limited thereto.

[0056] In one embodiment, the content of the auxiliary additive relative to the total weight of the first mixed solution may be 30 wt% or less.

[0057] For example, the content of the auxiliary additive relative to the total weight of the first mixed solution may be 1 wt% or more, 3 wt% or more, or 5 wt% or more, and may be 25 wt% or less, 20 wt% or less, or 15 wt% or less.

[0058] When the content of the above auxiliary additive satisfies the above-mentioned range, the strength of the composite heat storage body can be improved, and the shape of the composite heat storage body can be stably maintained during drying and firing.

[0059] In one embodiment, the second mixed solution may include the first mixed solution, a solvent, and an acidic solution.

[0060] In one embodiment, the solvent may be water.

[0061] In one embodiment, the acidic solution may be a sulfuric acid solution.

[0062] In one embodiment, the type of acid may not be limited as long as the acid solution has a pH value of 5. For example, the acid solution may include nitric acid, hydrochloric acid, or acetic acid.

[0063] In one embodiment, the content of the solvent relative to the total weight of the second mixed solution may be 30 wt% to 70 wt% or 50 wt% to 60 wt%.

[0064] In one embodiment, the content of the acidic solution relative to the total weight of the second mixed solution can be appropriately adjusted within a range of 0.1 wt% to 5 wt% so that the pH of the second mixed solution is 5 or less.

[0065] In one embodiment, the extrusion molding conditions in the step of manufacturing a preliminary composite accumulator by extruding the second mixed solution may be appropriately applied to satisfy the particle size of the composite accumulator and the number of channels per square inch (CPSI) of the composite accumulator.

[0066] In one embodiment, the dryer applied when drying the preliminary composite accumulator may be a microwave dryer, a hot air dryer, a dielectric dryer, a reduced pressure dryer, or a vacuum dryer.

[0067] In one embodiment, the drying temperature and time may be appropriately applied to satisfy the particle size of the composite thermal accumulator and the number of channels per square inch (CPSI) of the composite thermal accumulator.

[0068] In one embodiment, the step of drying and firing the preliminary composite accumulator may further include a step of degreasing the preliminary composite accumulator after drying it. The degreasing in the degreasing step may be performed at 400°C for 2 hours.

[0069] In one embodiment, the firing temperature in the step of drying and firing the preliminary composite accumulator may be 600°C or higher.

[0070] For example, the firing temperature may be 1000°C or lower. For example, the firing temperature may be 600°C to 1000°C or 700°C to 900°C.

[0071] For example, in the above firing step, the firing time may be 2 to 5 hours.

[0072] Figures 2 and 3 are schematic diagrams showing the structure of a composite accumulator according to exemplary embodiments. For example, Figure 3 is a diagram showing the upper surface of a composite accumulator according to exemplary embodiments.

[0073] In this specification, "height direction" may refer to the direction in which channels are formed. For example, it may refer to the direction in which a gas containing a perfluorinated compound permeates. For example, it may refer to a direction perpendicular to the x-axis direction and y-axis direction of FIG. 3.

[0074] Referring to FIG. 2, the composite accumulator (100) may have a honeycomb shape including a plurality of channels (105). For example, the composite accumulator (100) may include a body (101), a plurality of channels (105), and a partition wall (106) defining the channels (105).

[0075] In one embodiment, when a perfluorinated compound passes through a composite accumulator (100), the area in contact with the catalyst (100) increases through a plurality of channels (105), thereby increasing the decomposition efficiency of the perfluorinated compound.

[0076] According to exemplary embodiments, a plurality of channels (105) may penetrate in opposite directions from one side of the body. For example, the channels (105) may penetrate from a first side (110) toward a second side (120) facing the first side (110).

[0077] According to exemplary embodiments, the channel (105) may be formed in the height direction. For example, the first side (110) and the second side (120) may be connected through the channel (150).

[0078] According to exemplary embodiments, the cross-sectional shape of the channel (105) may be constant in the height direction. For example, when the side surface (150) is cut in the height direction of the catalyst (100) parallel to the first surface (110) and the second surface (120), the cross-sectional shape of the channel (105) may be the same as the cross-sectional shape of the channel on the first surface (110) and / or the cross-sectional shape of the channel on the second surface (120). A gas including a perfluorinated compound may pass through the plurality of channels (105) penetrating the catalyst (100).

[0079] The cross-sectional shape of the channel (105) may not be limited to the cross-sectional shape of FIG. 2. For example, the cross-sectional shape of the channel (105) may correspond to a triangle, a rectangle, a square, a trapezoid, a rhombus, a hexagon, an oval, a circle, etc. Considering the contact area between the gas and the composite accumulator (100), the flow rate, the density of the catalyst material included in the composite accumulator (100), the strength of the composite accumulator (100), etc., the cross-section of the channel (105) may be formed into a triangle, a square, or a hexagon.

[0080] According to exemplary embodiments, a plurality of channels (105) may be defined through a bulkhead (106).

[0081] In exemplary embodiments, the body (101) and the bulkheads (106) may be made of the same material.

[0082] In some embodiments, each of the plurality of channels (105) may be spaced apart at a constant interval. For example, the channels (105) may be spaced apart in a direction perpendicular to the height direction by an amount corresponding to the thickness of the partition wall (106).

[0083] In one embodiment, the cross-section of each of the plurality of channels (105) may be rectangular, and the distance between the plurality of channels (105) (e.g., L2 in FIG. 3) may be the same.

[0084] In exemplary embodiments, the perfluorinated compound decomposition efficiency of the catalyst (100) can be further improved by controlling the shape of the channel (105), the number of channels (105), etc.

[0085] In exemplary embodiments, the diameter of the channel (105) can be measured from the diameter of a channel located on the first side (110) or the second side (120). For example, the diameter of the channel can be measured from a cross-section of the channel (105) identified on the first side (110).

[0086] In one embodiment, the number of channels per square inch (CPSI) of the composite thermal accumulator may be from 30 to 70.

[0087] For example, the number of channels per square inch (CPSI) of the composite accumulator may be from 30 to 100, from 30 to 90, from 30 to 80, or from 30 to 60.

[0088] When the number of channels per square inch (CPSI) of the composite accumulator satisfies the aforementioned range, excellent strength can be maintained without pressure loss. In addition, the unit area available for contact with the perfluorinated compound can be increased, and gas mobility can be maintained, thereby increasing catalytic activity per unit time.

[0089] For example, if the number of channels per square inch (CPSI) of the composite accumulator is less than 30, the area supporting the catalyst layer on top of the composite accumulator may decrease, which may lower the strength of the product. If the number of channels per square inch (CPSI) of the composite accumulator exceeds 100, the pressure loss within the regenerative catalyst system using the composite accumulator may increase, which may lower the operational efficiency.

[0090] In this specification, the number of channels per square inch may be a value measured in a cross-section perpendicular to the height direction of the channels of the composite heat storage body (100).

[0091] In order to improve the life of the catalyst, decomposition efficiency, etc., the structure of the composite accumulator (100) can be adjusted. The structure of the composite accumulator (100) can be adjusted within a range in which pores, density, strength, etc. are maintained.

[0092] For example, the horizontal and vertical lengths of the composite heat accumulator (100) may be 10 mm to 30 mm, respectively. The horizontal and vertical lengths may represent the horizontal and vertical lengths of the first cross-section (110) or the second cross-section (120). For example, the height of the composite heat accumulator (100) may be 10 mm to 25 mm. The above lengths are exemplary, and the size of the composite heat accumulator (100) is not limited thereto.

[0093] In exemplary embodiments, the composite accumulator (100) may include a catalyst material including a metal oxide having catalytic activity for decomposition of a perfluorinated compound.

[0094] According to exemplary embodiments, the catalyst (100) may include a catalyst material having catalytic activity.

[0095] In some embodiments, the composite accumulator (100) may be a monolithic structure formed integrally.

[0096] In exemplary embodiments, a plurality of composite accumulators (100) may be stacked to form a composite accumulator assembly (200).

[0097] FIG. 4 is a schematic diagram showing a reactor including a composite accumulator assembly (200) according to exemplary embodiments.

[0098] Referring to FIG. 4, the reactor (200) may include a chamber (210) and a composite accumulator assembly (200) disposed within the chamber (210). A composite accumulator assembly (200) in which a plurality of the above-described catalysts are laminated may be disposed within the reactor (200). In FIG. 4, the composite accumulators (100) are illustrated separately for convenience of explanation, but a plurality of composite accumulators (100) may be in direct contact with each other.

[0099] According to exemplary embodiments, in catalysts comprising a plurality of composite accumulators (100), each channel may be connected to allow fluid to pass through.

[0100] For example, a plurality of composite accumulators (100) may each include channels having the same diameter, and a second surface (120) of one composite accumulator (100) and a first surface (110) of another composite accumulator (100) may be laminated so that the channels face each other and come into contact with each other, thereby forming a catalyst assembly (200).

[0101] For example, side surfaces (150) of multiple identical composite accumulators (100) can be joined to form a composite accumulator assembly (200).

[0102] The number of composite accumulators (100) included in the composite accumulator assembly (200) is not limited, but can be determined by considering the volume of the reactor.

[0103] A gas containing a perfluorinated compound may be injected into one end of the reactor. For example, the gas containing a perfluorinated compound may contact the catalyst assembly (200) along the direction of the arrow in FIG. 4, and a gas containing a compound generated by the decomposition of the perfluorinated compound may be discharged into the other end of the reactor.

[0104] A composite accumulator assembly (200) comprising catalysts according to the above-described embodiments can exhibit improved perfluorinated compound removal efficiency. In addition, the composite accumulator assembly (200) can be used continuously and repeatedly.

[0105] According to exemplary embodiments, the perfluorinated compound removal efficiency of the composite accumulator assembly (200) may be 49% or greater, 55% or greater, 58% or greater, or 62% or greater. For example, the perfluorinated compound removal efficiency may be 90% or less, 80% or less, or 70% or less.

[0106] When injecting a gas containing 300 ppm to 700 ppm of a perfluorinated compound into a composite heat storage body assembly (200) for 1 hour is considered as one cycle, the initial perfluorinated compound removal efficiency may represent the perfluorinated compound removal efficiency within 50 cycles, and the long-term perfluorinated compound removal efficiency may represent the perfluorinated compound removal efficiency within 200 to 500 cycles.

[0107] For example, the removal efficiency of the perfluorinated compound can be calculated according to Equation 5 below.

[0108] [Formula 5]

[0109] Perfluorinated compound removal efficiency (%) = {1-(C E / C I )}×100

[0110] In equation 5, C E is the concentration of perfluorinated compound at the outlet of the reactor (200), and C I is the concentration of perfluorinated compound at the inlet of the reactor (200).

[0111] The removal efficiency of the above perfluorinated compound may represent the removal efficiency at a reaction temperature of 650°C or higher, or 700°C, unless a separate reaction temperature is specified. Generally, the decomposition of the perfluorinated compound can achieve a high conversion rate at a temperature of 700°C or higher. However, when the catalyst according to the above-described embodiments is included, a high conversion rate can be achieved even at a relatively low temperature due to improved gas flowability, increased surface area of ​​the composite heat storage body (100), and / or increased heat transfer efficiency.

[0112] According to exemplary embodiments of the present invention, a method for decomposing a perfluorinated compound using the above-described composite accumulator or composite accumulator assembly is provided.

[0113] According to exemplary embodiments, a catalyst assembly (200) for decomposing perfluorinated compounds can be prepared. The composite accumulator assembly (200) can be, for example, an assembly of the composite accumulator (100) described above.

[0114] According to exemplary embodiments, a gas containing a perfluorinated compound can be injected into one side of the catalyst assembly for decomposing a perfluorinated compound.

[0115] For example, the perfluorinated compound can be decomposed by contacting the above-described catalyst or catalyst assembly with a gas containing the perfluorinated compound within a predetermined reaction temperature range.

[0116] According to exemplary embodiments, the perfluorinated compound can be decomposed at a temperature of 650°C or higher, from 650°C to 800°C, or from 650°C to 750°C.

[0117] According to exemplary embodiments, the content of the perfluorinated compound in the gas comprising the perfluorinated compound may be from 100 ppm to 1,000 ppm, from 200 ppm to 900 ppm, from 250 ppm to 850 ppm, or from 300 ppm to 800 ppm.

[0118] According to exemplary embodiments, the gas containing the perfluorinated compound may contain water (H2O). For example, the differential pressure described above can be calculated by calculating the partial pressure of water vapor.

[0119] According to exemplary embodiments, the moisture content of the gas containing the perfluorinated compound may be from 1% to 20% by volume, from 3% to 17% by volume, from 5% to 15% by volume, or from 6% to 12% by volume.

[0120] The gas containing the above perfluorinated compound may contain a remainder of air.

[0121] Hereinafter, preferred embodiments are presented to help understand the present invention, but these embodiments are only illustrative of the present invention and do not limit the scope of the appended claims. It is obvious to those skilled in the art that various changes and modifications to the embodiments are possible within the scope and technical idea of ​​the present invention, and it is also natural that such changes and modifications fall within the scope of the appended claims.

[0122] Examples and Comparative Examples

[0123] Example 1

[0124] (1) Waste catalyst crushing

[0125] Alumina-based waste catalyst was ground in a pin mill to produce powder with a particle size of 50 μm. “Particle size” refers to the particle size of the powder obtained by grinding the alumina-based waste catalyst based on the D90 value.

[0126] (2) Heat treatment

[0127] The above powder was heat-treated at a temperature of 200°C for 4 hours.

[0128]

[0129] (3) Preparation of the first mixed solution

[0130] 60 parts by weight of the above heat-treated powder, 30 parts by weight of gamma alumina, and 10 parts by weight of silica were mixed in a mixer to prepare 100 parts by weight of a first mixed solution.

[0131]

[0132] (4) Preparation of the second mixed solution

[0133] 70 parts by weight of water and 2 parts by weight of sulfuric acid solution were mixed with the first mixed solution using a mixer to prepare 100 parts by weight of a second mixed solution.

[0134]

[0135] (5) Manufacturing of preliminary composite heat storage agent

[0136] The above second mixed solution was extruded to produce a preliminary composite heat accumulator. Specifically, a preliminary composite heat accumulator having a honeycomb shape including channels with a rectangular cross-section was produced by extruding using an extruder to have a CPSI of 50.

[0137]

[0138] (6) Drying and firing

[0139] The above preliminary composite accumulator was dried and degreased at 400°C for 2 hours. Thereafter, a honeycomb-shaped composite accumulator was manufactured by firing at a temperature of approximately 800°C for 2 hours.

[0140]

[0141] Examples 2 to 12, Comparative Examples 1 to 4

[0142] By adjusting the particle size of the powder, the content of the spent catalyst, the content of the alumina binder, the content of the auxiliary additive, the sintering temperature, etc. as shown in Table 1 below, the structure of the honeycomb-shaped composite heat accumulator was adjusted, and the channel density (CPSI) was changed as shown in Table 1 below, and a composite heat accumulator was manufactured according to the same manufacturing method as in Example 1, except that the composite heat accumulator was manufactured.

[0143] Classification Particle size (㎛) Channel density (CPSI) Spent catalyst (wt%) Alumina binder (wt%) Auxiliary additive (wt) %) Firing temperature (℃) Example 15050603010800230506030108003100506030108004305060202080053050701515800630506030106007305060301010008307060301080093050502525800103050600408001130506010308001230506010101500Comparative Example 1205060301080021505060301080031050603010800416050603010800

[0144]

[0145] Experimental example

[0146] (1) Evaluation of shape stability of composite heat storage body

[0147] The shape stability of the composite accumulators manufactured in the examples and comparative examples was visually evaluated based on the following criteria and is shown in Table 2 below. The specific evaluation criteria are shown in the photographs of Figs. 5 to 7.

[0148] ○: Maintaining shape (Fig. 5)

[0149] △: Crack occurrence (Fig. 6)

[0150] X: crumble (Fig. 7)

[0151]

[0152] (2) Pressure loss evaluation

[0153] The pressure loss of the composite accumulators manufactured in the examples and comparative examples was measured. Specifically, while injecting gas in one direction into the composite accumulator, the pressure loss was measured at 90 CMM / m using a pressure gauge. 2 The pressure loss according to the flow rate per unit area was measured based on . The measurement results are shown in Table 2 below.

[0154]

[0155] (3) Evaluation of perfluorinated compound (F-gas) removal efficiency

[0156] The composite accumulators according to the above examples and comparative examples were each processed into a 3-inch cylindrical shape with a volume of 0.343 L and filled into a 3-inch Inconel reactor. The reaction temperature was controlled at 600°C using an external heater, and a gas containing 500 ppm of a perfluorinated compound (tetrafluoromethane (CF4)) was passed through the Inconel reactor for 1 hour. The reactants were analyzed using Fourier transform infrared spectroscopy (FT-IR), and the removal efficiency of the perfluorinated compound was calculated. The specific reaction conditions and the removal efficiency of the perfluorinated compound are as follows, and the experimental results are shown in Table 2 below.

[0157] [Reaction conditions]

[0158] i) Air flow rate: 38.9 L / min

[0159] ii) Distilled water flow rate: 0.88 mL / min

[0160] iii) Space velocity: 7,000 / hr

[0161] [Perfluorinated compound removal efficiency calculation formula]

[0162] Removal efficiency (%) = {1-(C E / C I )}×100

[0163] In the above formula for calculating the efficiency of removing perfluorinated compounds, C E is the concentration of perfluorinated compound at the outlet of the above reaction tube, and C Iis the concentration of the perfluorinated compound at the inlet of the above reaction tube.

[0164]

[0165] (4) Heat capacity evaluation

[0166] The heat capacity of the composite heat storage body according to the above examples and comparative examples was evaluated and is shown in Table 2 below. Specifically, the measurement was performed using a Netzsch DSC 404F1 device and according to the ASTM E793 measurement method.

[0167] Pressure loss evaluation (mmH2O / mm) F-gas removal efficiency (%) Shape stability evaluation Heat capacity (J / kg K) Example 10.0664○44520.0664○45030.0662○44040.0662○38050.0661○33060.0663○32070.0649○70080.0964○Not measurable90.0658○403100.0655○320110.0658○330120.0610 or less○970 Comparative example 1Not measurableNot measurableXNot measurable20.0661△3803Not measurableNot measurableXNot measurable40.0660△350

[0168] According to Table 1 above, it can be confirmed that the composite accumulators according to the examples have superior shape stability and higher perfluorinated compound removal efficiency or higher heat capacity than the composite accumulators according to the comparative examples.

[0169] Specifically, Examples 1 to 3 were manufactured by grinding an alumina-based waste catalyst and applying a powder having a particle size (D90) of 30 ㎛ or more and less than 150 ㎛, thereby confirming that the composite heat storage agent had excellent shape stability, high efficiency in removing perfluorinated compounds, and excellent heat capacity compared to Comparative Examples 1 to 4.

[0170] Example 2 was able to confirm that the pressure loss was low and the operational efficiency was excellent, as the number of channels per square inch (CPSI) of the composite accumulator was 30 to 60, compared to Example 8 in which the number of channels per square inch (CPSI) of the composite accumulator was 70.

[0171] Examples 4 and 5 showed superior efficiency in removing perfluorinated compounds because the applied content of the alumina-based waste catalyst was higher than that of Example 9.

[0172] Comparing Examples 2, 4, 10, and 11, it was confirmed that the heat capacity improved as the content of alumina-based binder applied increased.

[0173] Comparing Examples 2, 6, 7 and 12, it was confirmed that as the firing temperature increased, the efficiency of removing perfluorinated compounds generally decreased, but the heat capacity increased.

Claims

1. A step of producing a powder having a particle size (D90) of 30 ㎛ or more and less than 150 ㎛ by crushing an alumina-based waste catalyst; A step of heat treating the above powder; A step of preparing a first mixed solution by mixing an alumina-based binder into the heat-treated powder; A step of preparing a second mixed solution by mixing the first mixed solution, solvent, and acidic solution; A step of manufacturing a preliminary composite heat accumulator by extruding the second mixed solution; and A method for manufacturing a composite accumulator, comprising the steps of drying and firing the above-mentioned preliminary composite accumulator.

2. A method for manufacturing a composite heat storage body according to claim 1, wherein the number of channels per square inch (CPSI) of the composite heat storage body is 30 to 70.

3. A method for manufacturing a composite heat storage body according to claim 1, wherein the content of the alumina-based waste catalyst relative to the total weight of the first mixed solution is 50 wt% to 95 wt%.

4. A method for manufacturing a composite heat storage body according to claim 1, wherein the content of the alumina-based binder relative to the total weight of the first mixed solution is 30 wt% or less.

5. A method for manufacturing a composite heat storage body according to claim 1, wherein the alumina-based binder comprises at least one selected from the group consisting of alpha alumina (α-Al2O3), beta alumina (β-Al2O3), gamma alumina (γ-Al2O3), delta alumina (δ-Al2O3), theta alumina (θ-Al2O3), kappa alumina (κ-Al2O3), and boehmite.

6. A method for producing a composite heat storage body according to claim 1, wherein the first mixed solution further comprises an auxiliary additive.

7. A method for manufacturing a composite heat storage body according to claim 6, wherein the content of the auxiliary additive relative to the total weight of the first mixed solution is 30 wt% or less.

8. In claim 6, the auxiliary additive is a compound containing tungsten, a compound containing lanthanum, silica, zeolite, cordierite, mullite, silica-alumina, titania, magnesia, Fe2O3 / TiO2, Fe2O3 / Al2O3, MgO / TiO2, ZrO2 / Al2O3, ZrO x A method for manufacturing a composite heat storage body, comprising at least one selected from the group consisting of / TiO2, CeO2 / TiO2, CeO2 / ZrO2, and V2O5 / TiO2.

9. A method for manufacturing a composite heat storage body according to claim 1, wherein in the step of heat-treating the powder, the heat-treating temperature is 200°C or higher.

10. A method for manufacturing a composite heat storage body according to claim 1, wherein in the step of drying and firing the preliminary composite heat storage body, the firing temperature is 600°C or higher.

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