Perfluorinated compound decomposition catalyst and preparation method thereof

Abstract

The invention relates to a decomposition catalyst of perfluorinated compounds PFCs (Perfluorocompounds) and a preparation method of the decomposition catalyst, and provides a PFC decomposition catalyst, a honeycomb type catalyst forming body and a preparation method of the honeycomb type catalyst forming body. Zinc as an activity improving component and tungsten (W) as an auxiliary component are added to one or more aluminum oxides selected from gamma aluminum oxide, aluminum hydroxide, boehmite and pseudo-boehmite at a weight ratio of Al: Zn: W = 100: (30-100): (1-11). The PFC decomposition catalyst according to the present invention has durability with respect to fluorine generated by PFC decomposition, also has a synergistic effect capable of improving reaction activity, and is capable of decomposing a perfluorinated compound at a low temperature compared to conventional PFC decomposition catalysts. Thus, it is possible to reduce the operating cost associated with continuous operation, while ensuring the durability of the system.

Description

Technical Field

[0001] The present invention relates to the decomposition of perfluorocompounds (PFCs), and more particularly to a perfluorocompound decomposition catalyst and a method for preparing the catalyst. Background Art

[0002] If the PFCs (CF4, C4F8, CHF3, CxHyFz) produced in the semiconductor process are discharged into the atmosphere, they will become serious greenhouse gases.

[0003]

Table 1

[0004] Greenhouse gas (chemical formula) Lifespan (years) GWP over 20 years* GWP over 100 years <![CDATA[Methane (CH4)]]> 12.4 86 34 <![CDATA[Nitrous oxide (N2O)]]> 121.0 268 298 <![CDATA[Carbon tetrafluoride (CF4)]]> 50000 4950 7350

[0005] *GWP (Global Warming Potential): The radiative forcing that a gas can absorb and retain when compared to carbon dioxide.

[0006] To treat PFCs contained in exhaust gases emitted from semiconductor processes, a process known for catalytic hydrolysis involves using an alumina catalyst and steam to decompose the PFCs at high temperatures of 700-900°C. This high-temperature decomposition reaction changes the properties of the alumina support, resulting in a decrease in specific surface area, a reduction in active sites, and a consequent decrease in durability.

[0007] CF4 hydrolysis reaction mechanism

[0008] CF4+2H2O→CO2+4HF(ΔG o =-150 kJ / mol). Summary of the Invention

[0009] Technical problems to be solved

[0010] Therefore, be necessary to improve the durability of PFC decomposition catalyst.In addition, compare with existing PFC decomposition catalyst, industry is to improve conversion activity to the requirement of PFC decomposition catalyst, improves durability simultaneously.Further, when improving activity and durability, consider the back pressure of PFC decomposition system, need the PFC decomposition catalyst of shape, size and intensity optimization.In addition, when considering the corrosion that fluoric acid (HF aqueous solution) causes, relatively low differential pressure, heat storage performance etc., except existing ball form, also require the honeycomb type catalyst molded body.

[0011] Solutions to technical problems

[0012] The solution to the technical problem of the present invention is to provide a PFC decomposition catalyst with high reactivity and durability, which is composed of zinc (Zn) as an active performance improving component and tungsten (W) as an auxiliary component in aluminum oxide.

[0013] Without limitation, the precursor of the zinc (Zn) used in the PFC decomposition catalyst can be zinc nitrate (Zn (NO3) 2), hydrated zinc sulfate (ZnSO4H2O), zinc acetate ((CH3CO2) 2Zn)), and the precursor of tungsten (W) can be ammonium metatungstate ((NH4) 6H2W 12 O 40 ·3H2O), ammonium paratungstate ((NH4) 10 H2W 12 O 42 ·4H2O), sodium tungstate (Na2WO4·2H2O), tungsten oxide (WO3), tungsten chloride (WCl6) or a mixture thereof, and the aluminum oxide can be selected from gamma alumina (γ-Al2O3), aluminum hydroxide (aluminum trihydroxide), boehmite and pseudo-boehmite.

[0014] In addition, according to the present invention, the W-Zn-Al catalyst provides a PFC decomposition catalyst of Al:Zn:W=(100:30-100:1-1) in a weight ratio.

[0015] The solution to another technical problem of the present invention is to provide a PFC decomposition catalyst prepared by an impregnation method, a coprecipitation method or a physical mixing method through a preparation method of the catalyst.

[0016] Another technical problem solved by the present invention is to provide a method for preparing a PFC decomposition catalyst molded body, comprising the steps of mixing zinc (Zn) as an activity-improving component and tungsten (W) as an auxiliary component with aluminum oxide; and molding the mixture into one or more forms such as particles, balls, pellets, rings, and honeycombs. Furthermore, the method further comprises forming the mixture into a slurry form and coating the slurry on a honeycomb carrier.

[0017] The solution to another technical problem of the present invention is to provide a method for PFC decomposition, comprising: making water vapor flow from the outside into the reactor interior in order to carry out hydrolysis reaction in a catalyst reactor that is filled with a PFC decomposition catalyst molded body.

[0018] Effects of the Invention

[0019] The PFC decomposition catalyst according to the present invention has durability for fluorine generated by PFC decomposition and has a synergistic effect of improving reaction activity.

[0020] Another effect of the present invention is to decompose perfluorochemicals under the lower temperature condition than existing PFC decomposition catalyst, reduce the running cost of continuous operation, more easily ensure the durability of system, and can utilize the high reaction activity of catalyst to make equipment miniaturization simultaneously.

[0021] The honeycomb-type catalyst molded body according to the present invention exhibits higher HF durability and relatively lower differential pressure than the pellet-type catalyst molded body, and has heat storage performance equivalent to that of existing heat storage materials. Therefore, when the honeycomb catalyst according to the present invention is applied to the position of the heat storage material, the effect of increasing the operating time due to the improved performance can be expected. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This chart shows the PFC decomposition performance evaluation of a PFC decomposition catalyst according to the present invention, composed of zinc (Zn) added to alumina as an active performance-enhancing component and tungsten (W) added as an auxiliary component, in both fresh (fresh) and degraded (aged) states after accelerated evaluation. Performance improvements were observed with the addition of zinc (Zn) as the active performance-enhancing component to alumina, while durability improvements were observed with the addition of tungsten (W) as an auxiliary component.

[0023] Figure 2a The performance evaluation chart based on Zn content shows the highest conversion rate at a weight ratio of Al:Zn = 100:62, while the lowest conversion rate is observed at a weight ratio of Al:Zn = 100:119. This suggests that the performance degradation is due to the formation of ZnO. In other words, while Zn itself, as an active performance-enhancing component, contributes to decomposition activity, the ZnO form does not contribute to performance improvement.

[0024] Figure 2b From the XRD analysis chart of the Zn content, a ZnO peak was confirmed at a weight ratio of Al:Zn = 100:119. Therefore, it was determined that the performance degradation at a weight ratio of Al:Zn = 100:119 was caused by the formation of ZnO.

[0025] Figure 3a This is a performance evaluation chart based on the firing temperature of a mixture with a weight ratio of Al:Zn=100:62. The higher the firing temperature, the higher the conversion rate. This can be judged to be the performance difference caused by the ZnAl2O4 / ZnO ratio.

[0026] Figure 3b This is an XRD analysis chart based on the calcination temperature of a mixture with a weight ratio of Al:Zn=100:62. It can be confirmed that the higher the calcination temperature, the higher the ZnAl2O4 formation ratio.

[0027] Figure 4This is a durability evaluation chart for a catalyst sample with an Al:Zn weight ratio of 100:62. The accelerated evaluation, marked in the chart, is performed after deactivating the catalyst via HF acid treatment. Compared to the existing catalyst A, both the fresh catalyst and the accelerated evaluation showed improved conversion rates at all conversion temperatures. Compared to the existing catalyst, the fresh catalyst sample showed a 32% performance improvement, while the degraded catalyst showed a 6% improvement. However, the performance degradation rate due to degradation increased to 61% for the catalyst sample, compared to 49% for the existing catalyst.

[0028] Figure 5a This is a design chart for auxiliary components to reduce the performance decline rate caused by degradation. As a catalyst sample with a weight ratio of Al:Zn:M = 100:63:11, M is selected from one of cobalt, nickel, tungsten, zirconium or molybdenum. In particular, it was confirmed that the auxiliary component W improves the durability to HF without reducing the initial performance of the catalyst under conditions of 700°C.

[0029] Figure 5b This is a graph showing the performance degradation rate according to the content of tungsten as an auxiliary component. When tungsten is added at 7 wt% compared to Al, the performance degradation rate is the smallest. When more tungsten is added, the performance degradation rate worsens.

[0030] Figure 6 This is a performance evaluation chart of a PFC decomposition catalyst based on a method for producing the PFC decomposition catalyst.

[0031] Figure 7 This is a chart evaluating the performance of a conventional PFC decomposition catalyst and a PFC decomposition catalyst according to the present invention before and after accelerated evaluation.

[0032] Figure 8 The following photographs compare the durability of various honeycomb carriers against hydrofluoric acid.

[0033] Figure 9 This is a graph showing the evaluation of differential pressure at each linear velocity using a pellet-shaped, four-hole PFC decomposition catalyst and a PFC decomposition catalyst coated on a honeycomb.

[0034] Figure 10 This chart shows the performance evaluation of a four-hole PFC decomposition catalyst and a PFC decomposition catalyst coated on a honeycomb. DETAILED DESCRIPTION

[0035] definition:

[0036] Perfluorinated compounds can include carbon-containing PFCs, nitrogen-containing PFCs, and sulfur-containing PFCs containing more than two fluorines (F). Carbon-containing PFCs can include not only CF4, CHF3, CH2F2, C2F4, C2F6, C3F6, C3F8, C4F8, C4F10 The PFCs may be saturated or unsaturated aliphatic components, and may also include cyclic aliphatic and aromatic perfluorocarbons. Nitrogen-containing PFCs may typically include NF3, and sulfur-containing PFCs may include SF4, SF6, etc. Further, PFCs may also include compounds that can be decomposed by catalysts to form gaseous products such as HF.

[0037] Acidic gases as used herein refer to gases that become acidic upon contact with water. Non-limiting examples include halogens, hydrogen halides, nitrogen oxides (NOx), sulfur oxides (SOx), acetic acid, sublimated mercury, hydrogen sulfide, and carbon dioxide. Acidic gases not only cause corrosion but also reduce catalyst activity.

[0038] The hydrolysis reaction between PFC and water is an endothermic reaction. Higher temperatures induce a more spontaneous decomposition reaction, thus accelerating PFC decomposition. However, high temperatures reduce the thermal stability of the catalyst. Specifically, operating conditions of 700-900°C are too high for the catalyst to maintain activity for extended periods without undergoing physical or chemical changes. Therefore, ensuring catalyst durability is a major challenge. In particular, it is necessary to develop a catalyst that can withstand the 700-900°C reaction atmosphere, where HF and water vapor are generated as byproducts.

[0039] The present invention provides a PFC decomposition catalyst having excellent decomposition activity and durability for PFCs used in semiconductor manufacturing processes, capable of maintaining catalytic activity for a long period of time. The present invention relates to a PFC decomposition catalyst having excellent performance in decomposing perfluorinated compounds at low temperatures, reducing operating costs for continuous operation, and easily ensuring system durability.

[0040] Several embodiments for achieving the purpose of the present invention are presented below.

[0041] A first embodiment of the present invention relates to a PFC decomposition catalyst, comprising zinc as an activity-improving component and tungsten (W) as an auxiliary component added to at least one alumina precursor selected from gamma alumina, aluminum hydroxide, boehmite, and pseudo-boehmite, in a weight ratio of Al:Zn:W of 100:30 to 100:1 to 11.

[0042] A second embodiment of the present invention provides a method for preparing Zn-W-Al catalyst powder, comprising: mixing an aqueous solution formed by dissolving a zinc precursor and a tungsten (W) precursor in distilled water with at least one alumina precursor selected from gamma alumina, aluminum hydroxide, boehmite, and pseudo-boehmite, and then drying and calcining the mixture, in a weight ratio of Al:Zn:W = 100:30 to 100:1 to 11.

[0043] In particular, a honeycomb-type catalyst molded body is provided by coating a honeycomb support with Zn-W-Al catalyst powder.

[0044] The third embodiment of the present invention provides a perfluorochemical treatment method, comprising: using the PFC decomposition catalyst of the first embodiment to decompose PFC from the gas containing perfluorochemical.

[0045] A fourth embodiment of the present invention relates to a semiconductor manufacturing process, comprising the step of using the PFC decomposition catalyst of the first embodiment to decompose perfluoro compounds from a gas containing perfluoro compounds.

[0046] In the PFC decomposition catalyst of the present invention, the precursor of zinc (Zn) is zinc nitrate (Zn(NO3)2), hydrated zinc sulfate (ZnSO4H2O), zinc acetate ((CH3CO2)2Zn)), and the precursor of tungsten (W) is ammonium metatungstate ((NH4)6H2W 12 O 40 ·3H2O), ammonium paratungstate ((NH4) 10 H2W 12 O 42 ·4H2O), sodium tungstate (Na2WO4·2H2O), tungsten oxide (WO3), tungsten chloride (WCl6) or a mixture thereof, and the aluminum oxide can be selected from alpha alumina, gamma alumina (γ-Al2O3), aluminum hydroxide (aluminum trihydroxide), boehmite and pseudo-boehmite.

[0047] According to one embodiment of the PFC decomposition catalyst of the present invention, after zinc and tungsten precursors are impregnated in gamma alumina sequentially or simultaneously, a decomposition catalyst comprising aluminum oxide, zinc and tungsten is prepared in a weight ratio of Al:Zn:W=100:30 to 100:1 to 11. The preparation of the PFC decomposition catalyst of the present invention can be prepared by selecting a method from among impregnation, coprecipitation and physical mixing.

[0048] In PFC decomposition catalyst according to the present invention, aluminium oxide performance activity improves the effect of composition and auxiliary component supporter or carrier, is preferably gamma-aluminium oxide.In addition, if can suppress gamma-aluminium oxide to the transfer of α phase, just have the synergistic effect that can keep the high resolving power of PFC for a long time.

[0049] As active improvement metal, if add zinc (Zn), aspect the transformation efficiency when improving PFC catalyst decomposition reaction, can obtain ideal result.In addition, as promotor or auxiliary component, after tungsten (W) impregnation, durability can be improved greatly.

[0050] The PFC decomposition catalyst prepared according to the present invention can be finally formed into the catalyst powder form by performing the following steps, namely drying under the condition more than 150 ℃, and calcining under 600~900 ℃ air atmosphere. The final shape of the PFC decomposition catalyst according to the present invention both can use catalyst powder to be manufactured into granularity such as ball, pill, ring, also can be shaped into honeycomb etc.

[0051] Hereinafter, a method for producing a honeycomb-type molded catalyst body will be described.

[0052] The catalyst powder can be prepared as a slurry suspension and then coated onto a honeycomb carrier to provide a honeycomb-shaped catalyst body. The slurry suspension is prepared by dispersing the catalyst powder in water to a solids content of 10-50%. An alumina-based binder is used as the binder, and the viscosity is adjusted with a surfactant. The resulting slurry suspension has a particle size of 5-20 μm.

[0053] Generally, it can be applied to the carrier used in automotive catalysts. The carrier can be a cylindrical single carrier, and the material can be made of cordierite, corundum-mullite or alumina. Simply put, in the cylindrical honeycomb carrier, a plurality of penetrating units with a roughly square cross-section are regularly formed along the length direction, and each penetrating unit is separated from each other by a thin unit wall. The catalyst slurry is coated or installed on the surface of the unit wall or inside the pores. Usually, the density of the unit is set to 200 units / inch 2 The thickness of the cell wall is set to about 0.3 mm.

[0054] The coating process is divided into a slurry suspension coating step, a drying step and a firing step. The slurry suspension or carrier coating is coated on the carrier at a dry increment of 100 to 500 g / L for 3 to 10 seconds. The excess slurry in the unit is removed by suction or air flow. After the carrier is dried at 80 to 150°C, it is fired at 400 to 800°C for 15 to 60 minutes to complete the catalyst molding.

[0055] PFC decomposition catalyst according to the present invention shows good decomposition effect and the durability aspect the perfluoro compound that contains halogen family acidic gas at decomposition removal, therefore, can be used for the technology that contains halogen family acidic gas, particularly can be used for decomposing the perfluoro compound that uses in the semiconductor manufacturing industry.

[0056] In the present invention, the temperature during the catalyst decomposition reaction of PFC is 600-800°C, preferably 650-750°C.

[0057] To carry out the hydrolysis reaction in the catalyst reactor, water may be flowed into the reactor from outside. Water may be supplied from a separate supply source located outside the reactor and supplied in the form of water vapor before flowing into the reactor. Preferably, purified water is used, and the supply rate may be adjusted based on the hydrolysis reaction rate.

[0058] Next, the preparation of the catalyst and the effects of the prepared catalyst will be described in detail.

[0059] <Example 1>

[0060] Preparation of Zn-Al catalyst (Al:Zn=100:31 weight ratio)

[0061] A solution prepared by dissolving 63 g of zinc nitrate in distilled water was mixed with 83 g of aluminum oxide, and then dried at 150° C. for 3 hours and then calcined at 750° C. for 10 hours.

[0062] <Example 2>

[0063] Preparation of Zn-Al catalyst (Al:Zn=100:62 weight ratio)

[0064] A solution prepared by dissolving 107 g of zinc nitrate in distilled water was mixed with 71 g of aluminum oxide, and then dried at 150° C. for 3 hours and then calcined at 750° C. for 10 hours.

[0065] <Example 3>

[0066] Preparation of Zn-Al catalyst (Al:Zn=100:119 weight ratio)

[0067] A solution prepared by dissolving 162 g of zinc nitrate in distilled water was mixed with 56 g of aluminum oxide, and then dried at 150° C. for 3 hours and then calcined at 750° C. for 10 hours.

[0068] <Example 4>

[0069] Preparation of W-Zn-Al catalyst (Al:Zn:W=100:62:11 weight ratio)

[0070] A solution of 5.5 g of ammonium metatungstate dissolved in distilled water was mixed with 95 g of the catalyst prepared in Example 2, and then dried at 150° C. for 3 hours and then calcined at 750° C. for 10 hours.

[0071] <Comparative Example 1>

[0072] Preparation of Co-Zn-Al catalyst (Al:Zn:Co=100:62:11 weight ratio)

[0073] A Co-Zn-Al catalyst was prepared by following the same method except that 20 g of cobalt nitrate was used instead of the ammonium metatungstate in Example 4 and dissolved in distilled water.

[0074] <Comparative Example 2>

[0075] Preparation of Ni-Zn-Al catalyst (Al:Zn:Ni=100:62:11 weight ratio)

[0076] A Ni-Zn-Al catalyst was prepared by following the same method except that 20 g of nickel nitrate was used instead of the ammonium metatungstate in Example 4 and dissolved in distilled water.

[0077] <Comparative Example 3>

[0078] Preparation of Zr-Zn-Al catalyst (Al:Zn:Zr=100:62:11 weight ratio)

[0079] A Zr-Zn-Al catalyst was prepared by following the same method except that 17 g of zirconium acetate was used instead of the ammonium metatungstate in Example 4 and dissolved in distilled water.

[0080] <Comparative Example 4>

[0081] Preparation of Mo-Zn-Al catalyst (Al:Zn:Mo=100:62:11 weight ratio)

[0082] The Mo-Zn-Al catalyst was prepared according to the same method except that 6 g of ammonium molybdate was used instead of the ammonium metatungstate in Example 4 and dissolved in distilled water.

[0083] <Example 5>

[0084] Preparation of W-Zn-Al catalyst (Al:Zn:W=100:62:2 weight ratio)

[0085] A solution of 1.1 g of ammonium metatungstate dissolved in distilled water was mixed with 99 g of the catalyst prepared in Example 2, and then dried at 150° C. for 3 hours and then calcined at 750° C. for 10 hours.

[0086] <Example 6>

[0087] Preparation of W-Zn-Al catalyst (Al:Zn:W=100:62:7 weight ratio)

[0088] A solution of 3.3 g of ammonium metatungstate dissolved in distilled water was mixed with 97 g of the catalyst prepared in Example 2, and then dried at 150° C. for 3 hours and then calcined at 750° C. for 10 hours.

[0089] <Example 7>

[0090] Preparation of W-Zn-Al catalyst (Al:Zn:W=100:62:7 weight ratio)

[0091] A solution prepared by dissolving 102 g of zinc nitrate and 3.3 g of ammonium metatungstate in distilled water was mixed with 69 g of aluminum oxide, and then dried at 150° C. for 3 hours and then calcined at 750° C. for 10 hours.

[0092] <Example 8>

[0093] After dispersing the catalyst powder prepared in Example 5 in water with a solid content of 10-50% to prepare a slurry suspension with a particle size of 5 to 20 μm, it is coated on a cylindrical monomer carrier made of alumina at a dry increment of 100 to 500 g / L, dried at 80 to 150°C, and fired at 400 to 800°C to complete the honeycomb catalyst molded body.

[0094] <Example 9>

[0095] The same procedure as in Example 8 was followed, except that a cylindrical single-body support made of cordierite was used.

[0096] <Example 10>

[0097] The same process as in Example 8 was carried out, except that a cylindrical single-body carrier made of corundum-mullite was used.

[0098] <Experimental Example 1>

[0099] In order to compare the removal efficiency of the catalysts or honeycomb-type catalysts prepared in the above examples and comparative examples for perfluorinated compounds (CF4), the performance was evaluated under the following experimental conditions.

[0100] 18 ml of each catalyst prepared in the examples and comparative examples was placed in a 1-inch Inconel reaction tube, and the reaction temperature was adjusted to 700°C using an external heater. The reaction was continued at a space velocity of 17000 h / min. -1 Tetrafluoromethane was decomposed under the following conditions in an atmosphere of 2000 ppm tetrafluoromethane (CF4), 6% oxygen (O2), and 10% water (H2O). The tetrafluoromethane removal efficiency was calculated according to the following mathematical formula 1, and the reactants were analyzed by FT-IR.

[0101] <Mathematical formula 1>

[0102] CF4 removal efficiency (%) = (CF4 concentration at reactor inlet - CF4 concentration at reactor outlet) / CF4 concentration at reactor inlet * 100

[0103] <Experimental Example 2>

[0104] Accelerated evaluation (Aged) The prepared catalyst or honeycomb catalyst was treated in a hydrofluoric acid (HF) solution for 3 hours, dried and calcined, and then evaluated under the same experimental conditions.

[0105] The evaluation results are summarized in Tables 2 and 3.

[0106]

Table 2

[0107]

[0108]

Table 3

[0109]

[0110] Next, the design process and evaluation results of selecting the active improving ingredient and auxiliary ingredient according to the present invention will be described with reference to the following tables and drawings.

[0111] Figure 1 The present invention provides a graph showing the PFC decomposition performance of a PFC decomposition catalyst in its fresh state and in its aged state after accelerated evaluation, using zinc (Zn) as the active improving component and tungsten (W) as the auxiliary component, supported by alumina. The present inventors have confirmed that the addition of zinc (Zn) as the improving component to alumina increases the CF4 conversion rate from 71% to 83%, while the addition of tungsten (W) as the auxiliary component improves the durability performance from 27% to 54% based on the conversion rate. The present inventors have thus determined the active improving component and the auxiliary component.

[0112] Figure 2a This is a performance evaluation chart based on Zn content. Compared with Al, the highest conversion rate is shown at a Zn content of 62 wt%. Compared with Al, a low conversion rate is shown at a Zn content of 119 wt%, which is judged to be a decrease in performance due to the formation of ZnO. In other words, it is judged that Zn itself has a positive effect on decomposition activity, but the ZnO form has a negative effect on performance improvement. Performance evaluation conditions and Figure 1 same.

[0113] Figure 2b The XRD analysis chart based on the Zn content shows a ZnO peak when adding 119 wt% Zn compared to Al. Therefore, it is concluded that the performance degradation at 119 wt% Zn compared to Al is due to the formation of ZnO.

[0114] Figure 3aThis is a performance evaluation chart comparing the firing temperature of a mixture of a zinc precursor (62 wt% Zn) and aluminum oxide with Al. The higher the firing temperature, the higher the conversion rate. This indicates that the ZnAl2O4 / ZnO ratio contributes to performance differences.

[0115] Figure 3b This is an XRD analysis chart obtained by comparing the calcination temperature of the Zn 62 wt% zinc precursor and alumina mixture with Al. It can be confirmed that the higher the calcination temperature, the higher the ZnAl2O4 formation ratio.

[0116] Figure 4 This chart shows the durability evaluation of alumina-supported catalyst samples with 29% by weight of Zn added as an activity-enhancing component compared to Al. Compared to the existing catalyst A, the conversion rate of the new catalyst and in accelerated evaluations improved at all conversion temperatures. Specifically, at 700°C, the new catalyst sample showed a 32% improvement over the existing catalyst, and a 6% improvement in the degraded state. However, the performance degradation rate due to degradation increased to 61% for the catalyst sample, compared to 49% for the existing catalyst. Therefore, the addition of auxiliary components to reduce the performance degradation rate was considered.

[0117] Figure 5a This chart shows auxiliary component design for reducing the rate of performance loss due to degradation. Cobalt, nickel, tungsten, zirconium, or molybdenum were added to an Al:Zn catalyst containing 62% Zn by weight, at 11% by weight compared to Al, and the catalyst's performance and durability against HF were evaluated. The auxiliary component W, in particular, improved durability associated with degradation.

[0118] Figure 5b This is a graph measuring the performance degradation rate according to the auxiliary component, tungsten content. Compared with Al, the performance degradation rate is the smallest when 7 wt% of tungsten is added. If more tungsten is added, the performance degradation rate will worsen.

[0119] Figure 6 Regarding the method of adding the active improving ingredient zinc and the auxiliary ingredient tungsten, even if the two ingredients are added at the same time, there is no difference from adding them in steps.

[0120] Figure 7 This is a chart evaluating the performance of a conventional PFC decomposition catalyst and a PFC decomposition catalyst according to the present invention before and after accelerated evaluation.

[0121] exist Figure 8 The study confirmed that after treatment with aqueous HF, the higher the silicon content in honeycomb carriers made of alumina, cordierite, or corundum-mullite, the faster the structural collapse. This means that alumina carriers are structurally stable, while cordierite carriers are relatively less structurally stable.

[0122] The thermal storage performance of the catalyst molded body using the alumina honeycomb carrier according to Example 8 was evaluated based on the temperature evaluation at the front and rear ends of the catalyst during engine evaluation. The results showed that the thermal storage performance was significantly better than that of the conventional thermal storage material (density 0.86 g / cm 3 ) has the same heat storage performance.

[0123] exist Figure 9 In the present invention, the differential pressure characteristics of a pellet-type catalyst (16 mm in diameter and 19 mm in length), a 4-hole-type catalyst (14.2 mm in length / horizontal and 10 mm in length), a curved-angle 4-hole-type catalyst (15 mm in length / horizontal and 10 mm in length) and an alumina honeycomb carrier according to Example 8 were compared, and the results confirmed that if a honeycomb carrier is used, the differential pressure drop rate increases by more than 90%.

[0124] Figure 10 It shows that in terms of CF4 decomposition performance, the performance of alumina honeycomb catalyst is about 2 times better than that of 4-hole type catalyst.

[0125] With reference to the above-mentioned embodiment and experimental example, it can be known that the aluminum oxide catalyst for decomposing PFC according to the embodiment of the present invention and its preparation method can improve the decomposition efficiency and durability of PFC. Although the present invention has been described with reference to the preferred embodiments of the present invention, it will be understood that those skilled in the art can implement various revisions and changes to the present invention without departing from the scope of the present invention and the field of the invention described in the following claims.

Claims

1. A PFC decomposition catalyst formed body coated with a catalyst composition on a honeycomb carrier, characterized in that: Zinc as an active improving component and tungsten (W) as an auxiliary component are added to at least one alumina selected from gamma alumina, aluminum hydroxide, boehmite and pseudo-boehmite, and the weight ratio of Al:Zn:W is 100:30 to 100:1 to 11.

2. The PFC decomposition catalyst molded body according to claim 1, wherein The honeycomb carrier is made of alumina, cordierite or corundum-mullite.

3. A PFC treatment method, characterized in that: include: Use the PFC decomposition catalyst molded body of claim 1, the step of decomposing PFC in the gas containing PFC, and the temperature of the decomposition step is 600~800 ℃.

4. The PFC treatment method according to claim 3, characterized in that: The processing method is used in semiconductor manufacturing processes.

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