Catalyst for decomposing perfluorinated compounds

Abstract

Embodiments of the present invention provide a catalyst for decomposing perfluorinated compounds. The catalyst for decomposing a perfluorinated compound comprises: a first catalyst comprising alumina; and a second catalyst comprising an oxide of at least one selected from the group consisting of Zr, Ce and Ga, wherein the ratio of the weight of the second catalyst to the total weight of the first catalyst is 0.02 to 0.3. The catalyst for decomposing a perfluorinated compound may have improved lifespan characteristics and initial activity.

Description

Technical Field

[0001] The present invention relates to catalysts for the decomposition of perfluorinated compounds. Background Art

[0002] Perfluorocompounds (PFCs) are compounds containing a large amount of fluorine (F) substitution in aliphatic hydrocarbons, and their regulation has been strengthened in recent years. The global warming potential of perfluorocompounds is thousands to tens of thousands times that of carbon dioxide, and they are pointed out as the main cause of global warming. In addition, some of these perfluorocompounds are used as coating agents for cooking utensils or paper cups or as refrigerants, but are considered to cause brain, nerve and / or liver toxicity and disrupt hormones.

[0003] The main source of perfluorinated compounds is the production process of semiconductor devices such as memory or LCD. For example, perfluorinated compounds (such as CF4) are widely used as etching agents in etching processes and reactor cleaning agents in chemical vapor deposition processes during semiconductor production processes, and then they are discharged in large quantities.

[0004] As a method for removing perfluorinated compounds, a catalytic decomposition method capable of decomposing at low temperatures can be used. The catalytic decomposition method may include, for example, a process of passing the perfluorinated compound through a harmful gas decomposition device including a catalyst layer. During the passing process, pressure loss occurs, and if the pressure loss of the entire device increases, it may be difficult to operate the device for a long time.

[0005] In addition, as a main material of a catalyst for decomposition of perfluorinated compounds, alumina (Al2O3) may be used. However, the alumina catalyst undergoes a phase change when exposed to perfluorinated compounds for a long time, which may reduce the efficiency of the catalyst.

[0006] Therefore, there is a need for a catalyst for decomposing perfluorinated compounds having improved life characteristics and structural stability. For example, Korean Patent Laid-Open Publication No. 10-2007-0116498 discloses an apparatus for removing perfluorinated compounds, but there are limitations in ensuring sufficient life characteristics and stability. Summary of the invention

[0007] The object of the present invention is to provide a catalyst for the decomposition of perfluorinated compounds having improved lifetime characteristics and stability.

[0008] 1. A catalyst for decomposition of a perfluorinated compound, comprising: a first catalyst comprising aluminum oxide; and a second catalyst comprising at least one oxide selected from the group consisting of Zr, Ce and Ga, wherein the ratio of the weight of the second catalyst to the total weight of the first catalyst is 0.02 to 0.3.

[0009] 2. The catalyst for decomposition of perfluorinated compounds according to 1 above, wherein the alumina comprises at least one form selected from the group consisting of boehmite (hydrated alumina), α alumina (α-alumina), γ alumina (γ-alumina), δ alumina (δ-alumina) and θ alumina (θ-alumina).

[0010] 3. The catalyst for decomposition of perfluorinated compounds according to 1 above, wherein the second catalyst comprises at least one selected from the group consisting of zirconium oxide (ZrO 2 ), cerium oxide (CeO 2 ) and gallium oxide (Ga 2 O 3 ).

[0011] 4. The catalyst for decomposition of perfluorinated compounds according to 1 above, wherein the second catalyst comprises at least one selected from the group consisting of zirconium oxide, cerium oxide and gallium oxide, and a mixed phase of aluminum oxide and phosphorus.

[0012] 5. The catalyst for decomposing a perfluorinated compound according to 1 above, further comprising a third catalyst containing a phosphorus-containing compound.

[0013] 6. The catalyst for decomposing perfluorinated compounds according to 5 above, wherein the ratio of the converted weight of phosphorus contained in the third catalyst to the total weight of the first catalyst is 0.01 to 0.1, and the converted weight of phosphorus is the weight obtained by converting the content of phosphorus contained in the third catalyst into the content of P2O5.

[0014] 7. The catalyst for decomposition of a perfluorinated compound according to 5 above, wherein the third catalyst further comprises a compound containing at least one selected from the group consisting of B, S, P, Cs, Ca and K.

[0015] 8. The catalyst for decomposition of a perfluorinated compound according to 5 above, further comprising a fourth catalyst comprising at least one oxide selected from the group consisting of Zn, Ni, W, Co, Ni, Cr and Mo.

[0016] 9. The catalyst for decomposition of perfluorinated compounds according to 1 above, wherein the ratio of the crystal structure of the second catalyst measured by X-ray diffraction (XRD) analysis and defined by the following formula 1 is 0.2 to 0.9:

[0017] [Formula 1]

[0018] Crystal structure ratio = A / B

[0019] (In Formula 1, A is the XRD peak area corresponding to the monoclinic crystal structure of the second catalyst, and B is the XRD peak area corresponding to the tetragonal crystal structure of the second catalyst).

[0020] 10. The catalyst for decomposition of perfluorinated compounds according to 9 above, wherein the ratio of the weight of the fourth catalyst to the total weight of the first catalyst is 0.01 to 0.2.

[0021] 11. The catalyst for decomposition of perfluoro compounds according to 1 above, wherein the ratio of the weight of the first catalyst to the total weight of the catalyst for decomposition of perfluoro compounds is 0.67 to 0.96.

[0022] 12. The catalyst for decomposition of perfluorinated compounds according to 1 above, wherein the catalyst has a honeycomb structure shape including a plurality of through-channels formed therein.

[0023] 13. The catalyst for decomposition of perfluorinated compounds according to 12 above, wherein the number of through-channels per square inch (CPSI) in a plane direction perpendicular to the extending direction of the plurality of through-channels is 50 to 150.

[0024] 14. The catalyst for decomposition of perfluorinated compounds according to 12 above, wherein the channel length ratio defined by the following formula 2 is 1 to 5:

[0025] [Formula 2]

[0026] Channel length ratio = L / T

[0027] (In Formula 2, L is the major axis length of each of the plurality of through-channels in the planar direction, and T is the shortest distance between a through-channel adjacent to one side of the catalyst for decomposition of a perfluoro compound and the one side).

[0028] 15. An apparatus for decomposing a perfluorinated compound, comprising: a catalyst layer, the catalyst layer comprising the catalyst for decomposing a perfluorinated compound according to 12 above; and a heat storage body disposed below the catalyst layer.

[0029] In an exemplary embodiment, the catalyst for decomposing a perfluorinated compound comprises: a first catalyst comprising aluminum oxide and a second catalyst comprising at least one oxide selected from the group consisting of Zr, Ce, and Ga. The weight ratio of the first catalyst to the second catalyst may be adjusted to a predetermined range, thereby improving the decomposition performance and initial efficiency of the catalyst.

[0030] In some embodiments, the catalyst for decomposition of perfluorinated compounds may further include a third catalyst containing a phosphorus-containing compound. Thus, the durability and stability of the catalyst for decomposition of perfluorinated compounds may be improved.

[0031] In some embodiments, the catalyst for decomposition of perfluorinated compounds may further include a fourth catalyst including at least one oxide selected from the group consisting of Zn, Ni, W, Co, Ni, Cr, and Mo. Thus, the performance of the first catalyst and the second catalyst may be improved.

[0032] In some embodiments, the catalyst for decomposing perfluorinated compounds may have a honeycomb structure including a plurality of through-channels, thereby increasing the specific surface area capable of reacting with the gas to be treated, thereby improving the efficiency of removing harmful gases.

[0033] In some embodiments, the ratio between the length of the through channel in the plane direction and the wall thickness of the catalyst for decomposing perfluorinated compounds can be adjusted to a predetermined range. Therefore, the specific surface area of ​​the catalyst for decomposing perfluorinated compounds can be increased while suppressing the pressure loss of the gas to be treated. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 is a schematic diagram showing a catalyst for decomposition of a perfluorinated compound according to an exemplary embodiment;

[0035] Figure 2 is a schematic plan view showing a catalyst for decomposition of a perfluorinated compound according to an exemplary embodiment;

[0036] Figure 3 is a schematic cross-sectional view showing a reactor including a catalyst for decomposition of a perfluorinated compound according to an exemplary embodiment;

[0037] Figure 4 and Figure 5 is a graph showing the results of XRD analysis of Examples 6, 11 and 12; and

[0038] Figure 6 and Figure 7 : is a graph showing the XRD analysis results of Examples 15 and 19. DETAILED DESCRIPTION

[0039] An embodiment of the present invention provides a catalyst for decomposition of perfluorinated compounds, which comprises two or more different catalysts.

[0040] Hereinafter, embodiments of the present invention will be described in detail. However, these are merely exemplary, and the present invention is not limited to the specific embodiments described by way of example.

[0041] For example, perfluorocompounds (PFCs) may include CF4, CHF3, C3F6, CH2F2, C3F4, C2F6, C3F8, C4F 10 , C5F8, SF6, NF3, etc.

[0042] In an exemplary embodiment, the catalyst for decomposition of a perfluorinated compound may include a first catalyst and a second catalyst including compounds different from each other.

[0043] In an exemplary embodiment, the first catalyst may include aluminum oxide. Therefore, the chemical resistance of the catalyst for decomposing perfluorinated compounds to hydrofluoric acid derived from the gas to be reacted and acidic substances introduced from the semiconductor process can be improved. Therefore, the performance and durability of the catalyst for decomposing perfluorinated compounds can be improved.

[0044] For example, the first catalyst may be provided as a support.

[0045] For example, the alumina may include at least one form selected from the group consisting of boehmite (hydrated alumina), alpha alumina (α-alumina), gamma alumina (γ-alumina), delta alumina (δ-alumina), and theta alumina (θ-alumina).

[0046] In exemplary embodiments, the second catalyst may include an oxide of at least one selected from the group consisting of zirconium (Zr), cerium (Ce), and gallium (Ga).

[0047] For example, the second catalyst may be provided as a main catalyst, thereby allowing direct decomposition, hydrolysis and / or oxidative decomposition reactions of the perfluorinated compound to proceed.

[0048] For example, the second catalyst may include at least one selected from the group consisting of zirconium oxide (ZrO 2 ), cerium oxide (CeO 2 ), and gallium oxide (Ga 2 O 3 ).

[0049] For example, the second catalyst may be present in a mixed phase of at least one selected from the group consisting of zirconium oxide, cerium oxide, and gallium oxide, and aluminum oxide and phosphorus.

[0050] In an exemplary embodiment, a ratio of the weight of the second catalyst to the total weight of the first catalyst may be 0.02 to 0.3.

[0051] If the ratio of the weight of the second catalyst to the total weight of the first catalyst is less than 0.02, the introduction of the metal oxide of the second catalyst may be too small, resulting in reduced decomposition performance of the perfluoro compound.

[0052] If the ratio of the weight of the second catalyst to the total weight of the first catalyst exceeds 0.3, the decomposition effect of the perfluoro compound may be reduced relative to the weight of the introduced second catalyst.

[0053] For example, the first catalyst and the second catalyst may be present in the catalyst for decomposing the perfluorinated compound independently, or may interact with other components to form a composite metal oxide.

[0054] In some embodiments, the catalyst for decomposition of perfluorinated compounds may further comprise a third catalyst comprising a phosphorus (P)-containing compound.

[0055] The phosphorus-containing compound can transform the crystal structure of the first catalyst and / or the second catalyst. For example, the phosphorus contained in the phosphorus-containing compound can stabilize the crystal structure of the aluminum oxide contained in the first catalyst. For example, the phase transition of aluminum oxide having a γ-alumina (γ-alumina) crystal structure to an α-alumina (α-alumina) crystal structure can be suppressed by the phosphorus-containing compound, thereby improving the stability of the catalyst structure. Therefore, the durability and stability of the catalyst used for the decomposition of perfluorinated compounds can be improved.

[0056] For example, the phosphorus-containing compound may include at least one selected from the group consisting of P2O5, AlPO4, and a material formed in a mixed phase of aluminum oxide and phosphoric acid.

[0057] In some embodiments, the ratio of the converted weight of phosphorus contained in the third catalyst to the total weight of the first catalyst is 0.01 to 0.1, and the converted weight of phosphorus is a weight obtained by converting the content of phosphorus contained in the third catalyst into the content of P2O5.

[0058] Within the above range, the life characteristics of the catalyst for decomposing perfluoro compounds can be improved, and the conversion of aluminum oxide to aluminum phosphate (AlPO4) can be suppressed. Therefore, the reduction in initial activity can be prevented, while the life characteristics of the catalyst for decomposing perfluoro compounds can be improved.

[0059] In some embodiments, the third catalyst may further include a compound containing at least one selected from the group consisting of B, S, P, Cs, Ca, and K. Therefore, the life characteristics and initial activity of the catalyst for perfluorinated compound decomposition can be adjusted so that a catalyst having desired properties can be prepared.

[0060] According to some embodiments, the phosphorus-containing compound of the third catalyst may transform the crystal structure of the metal oxide included in the second catalyst.

[0061] For example, a ratio of the crystal structure of the second catalyst measured by X-ray diffraction (XRD) analysis and defined by the following Formula 1 may be 0.2 to 0.9.

[0062] [Formula 1]

[0063] Crystal structure ratio = A / B

[0064] In Formula 1, A is the XRD peak area corresponding to the monoclinic crystal structure of the second catalyst, and B is the XRD peak area corresponding to the tetragonal crystal structure of the second catalyst.

[0065] According to some embodiments, the catalyst for decomposing perfluorinated compounds may further include a fourth catalyst, the fourth catalyst comprising a material different from the first catalyst, the second catalyst, and the third catalyst. For example, the fourth catalyst may be provided as a co-catalyst to supplement the function of the main catalyst (e.g., the second catalyst) or have a catalytic function itself.

[0066] For example, the fourth catalyst may include an oxide of at least one selected from the group consisting of Zn, Ni, W, Co, Cr, and Mo.

[0067] For example, the fourth catalyst may include at least one selected from the group consisting of ZnO, NiO, WO 3 , CoO, Cr 2 O 3 , and MoO 2 .

[0068] In some embodiments, the ratio of the weight of the fourth catalyst to the total weight of the first catalyst may be 0.01 to 0.2. Within the above range, the removal performance of the perfluorinated compound may be improved while stably maintaining the crystal structures of the first catalyst and the second catalyst.

[0069] According to one embodiment, the weight of the first catalyst and the total weight of the catalyst for perfluoro compound decomposition may be 0.67 to 0.96. Within the above range, the durability and initial activity of the catalyst for perfluoro compound decomposition can be improved by adjusting the contents of the second catalyst, the third catalyst, and the fourth catalyst to the above range.

[0070] Figure 1 is a schematic diagram illustrating a catalyst for decomposition of a perfluorinated compound according to an exemplary embodiment.

[0071] Hereinafter, the structure of the catalyst for decomposition of perfluorinated compounds according to an exemplary embodiment will be described with reference to the accompanying drawings. However, the accompanying drawings are intended to describe exemplary embodiments, and the shape of the present invention is not limited to the shape shown in the accompanying drawings.

[0072] Reference Figure 1 The catalyst (100) for decomposing perfluorinated compounds may have a honeycomb structure.

[0073] The honeycomb structure shape may have, for example, a plurality of through-channels (110) through which the gas to be treated (eg, perfluorinated compound gas) may pass. Therefore, the catalyst having the honeycomb structure shape has a large specific surface area capable of reacting with the gas to be treated, so that the efficiency of removing harmful gases can be improved.

[0074] For example, the honeycomb structure shape may have a monolithic shape. Therefore, when the gas to be treated passes through the catalyst (100) for decomposing perfluoro compounds, pressure loss may be reduced.

[0075] For example, the honeycomb structure may have a shape such as a hexahedron, a triangular prism, a pentagonal prism, a hexagonal prism, etc., preferably a hexahedron or a regular triangular prism. In this case, the space efficiency of the reactor in which the catalyst (100) for decomposing perfluoro compounds having a honeycomb structure shape is installed can be improved.

[0076] For example, the catalyst (100) for decomposition of perfluorinated compounds having a honeycomb structure shape may have a length of 50 to 150 mm and a height of 50 to 150 mm on each side of a base side.

[0077] Figure 2 is a schematic plan view showing a catalyst for decomposition of a perfluoro compound according to an exemplary embodiment.

[0078] For example, the greater the number of through-channels (110) per unit area, the more the specific surface area increases, thereby improving the decomposition performance of the catalyst, but the pressure loss may increase when the gas to be treated passes therethrough.

[0079] Reference Figure 2 In a plane direction perpendicular to the extension direction of the plurality of through-channels (110), the number of through-channels (110) per square inch (channels per square inch, CPSI) may be 50 to 150.

[0080] The term "planar direction" as used herein may mean a direction in which the cross section of the catalyst (100) for decomposing perfluoro compounds is observed perpendicularly to the thickness direction of the catalyst (100) for decomposing perfluoro compounds (e.g., the extension direction of the plurality of through-channels (110)).

[0081] In the above CPSI range, since the specific surface area of ​​the catalyst (100) for decomposing perfluorinated compounds is increased, excessive pressure loss can be prevented while improving performance.

[0082] According to some embodiments, the channel length ratio defined by the following Formula 2 may be 1 to 5.

[0083] [Formula 2]

[0084] Channel length ratio = L / T

[0085] In Formula 2, L is the major axis length of each of the plurality of through-channels (110) in the plane direction, and T is the shortest distance between a through-channel adjacent to one side of the catalyst (100) for decomposing perfluoro compounds and the one side.

[0086] The channel length ratio may mean, for example, a ratio between the length L of one side of the through channel (110) in the planar direction and the wall thickness T of the catalyst (100) for decomposition of perfluoro compounds.

[0087] In the above range of the channel length ratio, the effect of improving the specific surface area can be fully achieved while suppressing the pressure loss.

[0088] According to one embodiment, the shape and size of each of the plurality of through-channels (110) in the planar direction may be substantially the same.

[0089] Hereinafter, a reactor including the above-mentioned catalyst for decomposition of perfluoro compounds will be described. However, the reactor is only one example of using the catalyst for decomposition of perfluoro compounds, and the use of the catalyst for decomposition of perfluoro compounds is not limited to the reactor.

[0090] Figure 3 is a schematic cross-sectional view illustrating a reactor including a catalyst for decomposition of a perfluoro compound according to an exemplary embodiment.

[0091] Reference Figure 3 , a reactor (200) including a catalyst (100) for decomposition of perfluorinated compounds can be formed.

[0092] According to some embodiments, a plurality of catalysts (100) for decomposition of perfluorinated compounds having a honeycomb structure shape may be joined or bonded in a planar direction or a vertical direction to form a catalyst layer (210).

[0093] The reactor (200) may include, for example, a catalyst layer (210) and a heat storage body (220).

[0094] For example, the gas containing the perfluorinated compound may pass through the heat storage body (220) and the catalyst layer (210) in sequence, and in the process, the perfluorinated compound may be removed. For example, the heat storage body (220) may heat the gas containing the perfluorinated compound to promote the reaction of the perfluorinated compound with the catalyst layer (210).

[0095] Below, for the convenience of understanding the present invention, specific experimental examples are proposed. However, the following examples are provided only to illustrate the present invention, and it will be apparent to those skilled in the art that various changes and modifications can be made within the scope and spirit of the present invention. Such changes and modifications are certainly included in the appended claims.

[0096] [Evaluation Example 1]

[0097] (1) Examples 1 to 4 and Comparative Examples 1 and 2

[0098] Alumina (Al2O3) was used as a first catalyst, and zirconium oxide (ZrO2) was used as a second catalyst.

[0099] Prepare 77 g of aluminum oxide.

[0100] The solution was prepared by dissolving zirconium oxide in distilled water in an amount such that the ratio of the weight of zirconium oxide to the weight of aluminum oxide was the value listed in Table 1 below.

[0101] 77 g of alumina was added and mixed into the prepared solution to be loaded. The mixture was dried for the first time at 40° C. and then dried for the second time at 110° C. for 8 hours. The second dried mixture was heated to 750° C. at a rate of 2° C. / min and calcined for 6 hours to prepare a catalyst for the decomposition of perfluorinated compounds.

[0102] (2) Evaluation of initial activity - CF4 removal efficiency (1 hour)

[0103] 7.6 g of each of the catalysts for perfluoro compound decomposition prepared according to Examples 1 to 4 and Comparative Examples 1 and 2 was separated and filled into a 3 / 4 inch Inconel reaction tube. The reaction temperature was adjusted to 700° C. using an external heater, and a gas containing 3,000 ppm of tetrafluoromethane (CF4) was passed through the reaction tube for 1 hour.

[0104] The detailed reaction conditions are as follows.

[0105] i) Air flow: 370cc / min

[0106] ii) Distilled water flow rate: 0.04mL / min

[0107] iii) Airspeed: 2,000 / hr

[0108] The CF4 removal efficiency was calculated using the following formula 3, and the reactants were analyzed using Fourier transform infrared spectroscopy (FT-IR).

[0109] [Formula 3]

[0110] CF4 removal efficiency (%) = {1-(C E / C I )}*100

[0111] In formula 3, C E is the CF4 concentration at the outlet of the reaction tube, C I is the CF4 concentration at the inlet of the reaction tube.

[0112] The evaluation results are shown in Table 1 below.

[0113] [Table 1]

[0114]

[0115] Referring to Table 1, in Examples 1 to 4 in which the ratio of the weight of the second catalyst to the weight of the first catalyst was 0.02 to 0.3, compared with Comparative Examples 1 and 2, the initial efficiency was improved.

[0116] In Comparative Example 1 in which the ratio of the weight of the second catalyst to the weight of the first catalyst was less than 0.02, the zirconium oxide content was insufficient, thereby resulting in a decrease in initial activity compared with Examples.

[0117] In Comparative Example 2 in which the ratio of the weight of the second catalyst to the weight of the first catalyst exceeded 0.3, the alumina content was reduced, thereby resulting in a decrease in initial activity compared with Examples.

[0118] [Evaluation Example 2]

[0119] (1) Examples 5 to 12

[0120] Alumina (Al2O3), zirconium oxide (ZrO2) and phosphoric acid (HPO4) were used as the first, second and third catalysts, respectively.

[0121] Prepare 77 g of aluminum oxide.

[0122] The solution was prepared by dissolving zirconium oxide in an amount such that the ratio of the weight of zirconium oxide to the weight of aluminum oxide was 0.1 and phosphoric acid in an amount such that the ratio of the weight of phosphoric acid to the weight of aluminum oxide was the values ​​listed in Table 2 below in distilled water.

[0123] 77 g of alumina was added and mixed into the prepared solution to be loaded. The mixture was dried for the first time at 40° C. and then dried for the second time at 110° C. for 8 hours. The second dried mixture was heated to 750° C. at a rate of 2° C. / min and then calcined for 6 hours to prepare a catalyst for the decomposition of perfluorinated compounds.

[0124] (2) Evaluation of initial activity - CF4 removal efficiency (1 hour)

[0125] For the catalysts for decomposition of perfluoro compounds prepared according to Examples 5 to 12, the initial activity was evaluated in the same manner as in (2) of Evaluation Example 1.

[0126] (3) Evaluation of life characteristics - CF4 removal efficiency (300 hours)

[0127] 7.6 g of each of the catalysts for perfluoro compound decomposition prepared according to Examples 5 to 12 was separated and filled into a 3 / 4 inch Inconel reaction tube. The reaction temperature was adjusted to 700° C. using an external heater, and a gas containing 3,000 ppm CF4 was passed through the reaction tube for 300 hours.

[0128] The detailed reaction conditions are as follows.

[0129] i) Air flow: 370cc / min

[0130] ii) Distilled water flow rate: 0.04mL / min

[0131] iii) Airspeed: 2,000 / hr

[0132] The CF4 removal efficiency was calculated using the above formula 3, and the reactants were analyzed using FT-IR.

[0133] (4) Evaluation of the crystal structure of alumina and zirconia

[0134] After the evaluation of (3) of Evaluation Example 2, the perfluoro compound catalyst was recovered and XRD analysis was performed on alumina and zirconium oxide.

[0135] 1) Evaluation of alumina crystal structure

[0136] XRD peaks corresponding to gamma alumina (γ-alumina), alpha alumina (α-alumina), and aluminum phosphate (AlPO 4 ) were observed, and peaks appearing in the XRD analysis results were recorded.

[0137] 2) Evaluation of the crystal structure of zirconium oxide

[0138] The catalysts for perfluorinated compound decomposition prepared according to Examples 5 to 12 were evaluated for the zirconium oxide crystal structure by XRD analysis.

[0139] Specifically, the area of ​​the XRD peak (2θ28° and 32°) corresponding to the monoclinic crystal structure (A = the sum of the areas of the 2θ28° peak + the 32° peak) and the area of ​​the XRD peak (2θ30° peak) corresponding to the hexagonal crystal structure (B = the area of ​​the 2θ30° peak) are measured, and then the measured A value and B value are substituted into the above formula 1 to obtain the ratio of the crystal structure of the second catalyst.

[0140] Figure 4 and Figure 5 is a graph showing the XRD analysis results of Examples 6, 11 and 12. Specifically, Figure 4 is a graph showing the XRD analysis results of Examples 6, 11 and 12 measured before injection of CF4 gas, Figure 5 It is a graph showing the XRD analysis results of Examples 6, 11 and 12 measured after passing CF4 gas for 300 hours.

[0141] The evaluation results are shown in Table 2 below.

[0142] [Table 2]

[0143]

[0144] Referring to Table 2, in Examples 5 to 9 in which the ratio of the weight of the third catalyst to the weight of the first catalyst was 0.01 to 0.1, the initial efficiency and life characteristics were improved compared to Examples 10 to 12 out of the above range.

[0145] In Examples 10 and 11, in which the ratio of the weight of the third catalyst to the weight of the first catalyst exceeded 0.1, alumina was converted to AlPO4, and the crystal structure of zirconium oxide was converted to a hexagonal structure in a relatively large amount. Therefore, the initial activity and life characteristics of the catalyst for decomposing perfluoro compounds were relatively reduced.

[0146] In Example 12, in which the ratio of the weight of the third catalyst to the weight of the first catalyst was less than 0.01, the phosphorus-containing compound was insufficient, so that the alumina crystal structure was relatively largely converted to α alumina. Therefore, the life characteristics of the catalyst for decomposing perfluorinated compounds were relatively reduced.

[0147] [Evaluation Example 3]

[0148] (1) Examples 13 to 19

[0149] Alumina (Al2O3), zirconium oxide (ZrO2), phosphoric acid (HPO4) and zinc (Zn) are used as the first, second, third and fourth catalysts, respectively.

[0150] Prepare 77 g of aluminum oxide.

[0151] The solution was prepared by dissolving in distilled water an amount of zirconium oxide such that the ratio of the weight of zirconium oxide to the weight of aluminum oxide was 0.1, an amount of phosphoric acid such that the ratio of the weight of phosphoric acid to the weight of aluminum oxide was 0.01, and an amount of zinc such that the ratio of the weight of zinc to the weight of aluminum oxide was the values ​​listed in Table 3 below.

[0152] 77 g of alumina was added and mixed into the prepared solution to be loaded. The mixture was dried for the first time at 40° C. and for the second time at 110° C. for 8 hours. The second dried mixture was heated to 750° C. at a rate of 2° C. / min and calcined for 6 hours to prepare a catalyst for the decomposition of perfluorinated compounds.

[0153] (2) Evaluation of initial activity - CF4 removal efficiency (1 hour)

[0154] For the catalysts for decomposition of perfluoro compounds prepared according to Examples 13 to 19, the initial activity was evaluated in the same manner as in (2) of Evaluation Example 1.

[0155] (3) Evaluation of life characteristics - CF4 removal efficiency (300 hours)

[0156] For the catalysts for perfluoro compound decomposition prepared according to Examples 13 to 19, life characteristics evaluation was performed in the same manner as in (3) of Evaluation Example 2, except that the reaction temperature was adjusted to 650°C.

[0157] (4) Evaluation of alumina crystal structure

[0158] XRD peaks corresponding to gamma alumina (γ-alumina) and zinc aluminate (ZnAl2O4) were observed, and peaks appearing in the XRD analysis results were recorded.

[0159] The evaluation results are shown in Table 3 below.

[0160] [Table 3]

[0161]

[0162] Referring to Table 3, in Examples 13 to 18 in which the ratio of the weight of the fourth catalyst to the weight of the first catalyst was 0.01 to 0.2, the life characteristics were relatively improved compared to Examples 6 and 19 which were out of the above range.

[0163] In Example 6 not including the fourth catalyst, the life characteristics when the reaction temperature is lower than 700° C. (650° C.) are reduced.

[0164] In Example 19 in which the fourth catalyst was contained in an excessive amount, the alumina crystal structure was transformed into ZnAl2O4, and therefore, the life characteristics of the catalyst for decomposition of perfluoro compounds were reduced.

[0165] Figure 6 and Figure 7 is a graph showing the XRD analysis results of Examples 15 and 19. Specifically, Figure 6 is a graph showing the XRD analysis results of Examples 15 and 19 measured before injecting CF4 gas, Figure 7 It is a graph showing the XRD analysis results of Examples 15 and 19 measured after passing CF4 gas for 300 hours.

[0166] Reference Figure 6 and Figure 7 In Example 19, in which the ratio of the weight of zinc to the weight of aluminum oxide exceeded 0.2, the peak corresponding to the zinc compound (2θ about 32°) increased significantly. Therefore, the CF4 removal efficiency was relatively reduced compared with other examples.

[0167] [Evaluation Example 4]

[0168] (1) Examples 20 to 24

[0169] An alumina mixture was prepared by mixing 2,700 g of gamma alumina and 300 g of forming aids (glycol additive, ether additive).

[0170] A solution was prepared by dissolving 87 g zinc nitrate, 54 g phosphoric acid (HPO4), and 195 g zirconium oxide in distilled water.

[0171] A mixture is prepared by adding and mixing the prepared alumina mixture into the prepared solution. The prepared mixture is put into an extrusion molding machine to prepare a formed body having a honeycomb structure shape.

[0172] At this time, the extruder is set so that the ratio of the length L of one through channel in the planar direction to the shortest distance T between an adjacent through channel adjacent to one side of the catalyst for decomposing perfluoro compounds and the one side (i.e., the channel length ratio of the above formula 2) is 4.

[0173] After the prepared shaped body was rapidly dried, a catalyst for decomposition of perfluorinated compounds was prepared by calcining at 110° C. for 4 hours, 550° C. for 2 hours, and 750° C. for 4 hours at a heating rate of 5° C. / min.

[0174] (2) Evaluation of life characteristics - CF4 removal efficiency (300 hours)

[0175] For the catalysts for decomposition of perfluoro compounds prepared according to Examples 20 to 24, evaluation of life characteristics was performed in the same manner as in (3) of Evaluation Example 2.

[0176] The evaluation results are shown in Table 4 below.

[0177] [Table 4]

[0178]

[0179] Referring to Table 4, in Examples 21 to 23 in which the channel length ratio (L / T) was 1 to 5, the CF4 removal efficiency after long-term operation was improved compared with Examples 20 and 24 which were not in the above range.

[0180] In Example 20 in which the channel length ratio is less than 1, the pressure loss of the gas to be treated through the through-channel is relatively increased. Therefore, the lifespan characteristics are relatively reduced.

[0181] In Example 24 in which the channel length ratio exceeded 5, the specific surface area of ​​the catalyst for decomposition of perfluoro compounds was relatively reduced. Therefore, the decomposition efficiency of the perfluoro compound per weight of the catalyst for decomposition of perfluoro compounds was relatively reduced.

Claims

1. A catalyst for the decomposition of a perfluorinated compound, comprising: a first catalyst comprising alumina; and a second catalyst comprising an oxide of at least one selected from the group consisting of Zr, Ce and Ga, The ratio of the weight of the second catalyst to the total weight of the first catalyst is 0.02 to 0.

3.

2. The catalyst for perfluorinated compound decomposition according to claim 1, wherein the alumina comprises at least one form selected from the group consisting of boehmite (hydrated alumina), alpha alumina (α-alumina), gamma alumina (γ-alumina), delta alumina (δ-alumina) and theta alumina (θ-alumina).

3. The catalyst for decomposition of perfluorinated compounds according to claim 1, wherein the second catalyst comprises at least one selected from the group consisting of zirconium oxide (ZrO2), cerium oxide (CeO2) and gallium oxide (Ga2O3).

4. The catalyst for decomposition of perfluorinated compounds according to claim 1, wherein the second catalyst comprises at least one selected from the group consisting of zirconium oxide, cerium oxide, and gallium oxide, and a mixed phase of aluminum oxide and phosphorus.

5. The catalyst for decomposition of perfluorinated compounds according to claim 1, further comprising a third catalyst containing a phosphorus-containing compound.

6. The catalyst for decomposition of perfluorinated compounds according to claim 5, wherein the ratio of the converted weight of phosphorus contained in the third catalyst to the total weight of the first catalyst is 0.01 to 0.1, and The phosphorus conversion weight is a weight obtained by converting the content of phosphorus contained in the third catalyst into the content of P2O5.

7. The catalyst for decomposition of a perfluorinated compound according to claim 5, wherein the third catalyst further comprises a compound containing at least one selected from the group consisting of B, S, P, Cs, Ca and K.

8. The catalyst for decomposition of a perfluorinated compound according to claim 5, further comprising a fourth catalyst comprising an oxide of at least one selected from the group consisting of Zn, Ni, W, Co, Ni, Cr and Mo.

9. The catalyst for perfluorinated compound decomposition according to claim 1, wherein the ratio of the crystal structure of the second catalyst measured by X-ray diffraction (XRD) analysis and defined by the following formula 1 is 0.2 to 0.9: [Formula 1] Crystal structure ratio = A / B (In Formula 1, A is the XRD peak area corresponding to the monoclinic crystal structure of the second catalyst, and B is the XRD peak area corresponding to the tetragonal crystal structure of the second catalyst).

10. The catalyst for decomposition of perfluorinated compounds according to claim 9, wherein a ratio of the weight of the fourth catalyst to the total weight of the first catalyst is 0.01 to 0.

2.

11. The catalyst for decomposition of perfluoro compounds according to claim 1, wherein a ratio of the weight of the first catalyst to the total weight of the catalyst for decomposition of perfluoro compounds is 0.67 to 0.

96.

12. The catalyst for decomposition of perfluorinated compounds according to claim 1, wherein the catalyst has a honeycomb structure shape including a plurality of through-channels formed therein.

13. The catalyst for decomposition of perfluorinated compounds according to claim 12, wherein the number of through-channels per square inch (CPSI) in a plane direction perpendicular to an extending direction of the plurality of through-channels is 50 to 150.

14. The catalyst for decomposition of perfluorinated compounds according to claim 12, wherein the channel length ratio defined by the following formula 2 is 1 to 5: [Formula 2] Channel length ratio = L / T (In Formula 2, L is the major axis length of each of the plurality of through-channels in the planar direction, and T is the shortest distance between a through-channel adjacent to one side of the catalyst for decomposing perfluoro compounds and the one side).

15. An apparatus for decomposing a perfluorinated compound, comprising: a catalyst layer comprising the catalyst for decomposition of a perfluorinated compound according to claim 12; and A heat storage body is arranged below the catalyst layer.

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