JP2006263577A - Treatment apparatus of halogen compound - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable an apparatus, which treats a halogen compound by using a catalyst, to perform a process for exchanging the catalyst in a short time. <P>SOLUTION: The treatment apparatus of the halogen compound is provided with: a preheater in which a gas to be treated containing the halogen compound is heated to a prescribed reaction temperature; a reactor in which incorporating the catalyst for decomposing the halogen compound incorporated in the heated gas is decomposed; and a cooler in which a decomposed gas discharged from the reactor is cooled, and is characterized in that the preheater is provided with a cooling water atomizing device therein. Cooling water is atomized in a preheating tub in the preceding stage of a reaction tower filled with the catalyst and the temperature decline of the preheater and the reactor filled with the catalyst is accelerated. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention efficiently detoxifies halogen compounds such as PFC gas used for etching and cleaning in semiconductors and liquid crystals.

  In the past, catalysts have been used for many hazardous gas treatments. For example, there are catalysts for automobile exhaust, catalysts for perfluorocompound (PFC) used in semiconductors and liquid crystals. The catalyst for automobile exhaust gas is usually rarely replaced if a catalyst is installed. However, the catalyst for PFC decomposition, etc. always needs to be measured, and the catalyst should be replaced when deterioration is recognized. .

PFC is a global warming gas that is thousands to tens of thousands of times that of CO ₂ . The Global Warming Council (COP3) has decided to reduce greenhouse gas emissions, and the industry has also decided on self-regulatory targets for atmospheric PFC emissions. As measures to suppress emissions, we are reviewing the process of use and developing alternative gas, but since development takes time, we have introduced a decomposition method.

  As the decomposition method, a combustion method, a chemical method, a plasma method, a thermal decomposition method, and the like are known. We have developed a catalytic technology that has a high decomposition rate at low temperature and can be decomposed at low cost, and commercialized a catalytic PFC decomposition unit. The catalytic method is characterized in that a very high decomposition rate can be obtained at a lower temperature than other methods.

  However, in recent years, the semiconductor / liquid crystal industry has demanded a high operation rate in addition to a high decomposition rate from the viewpoint of zero emission. In an ordinary catalyst decomposition apparatus, a reactor filled with a catalyst is heated from the outside by a heater. For this reason, when replacing the catalyst, a process is required in which the heater output is once left to cool to a predetermined temperature, and after cooling to a predetermined temperature, the catalyst is extracted, filled with a new catalyst, and heated again to the predetermined temperature. It was. With this method, it takes about a day to stop the device and restart it.

  In treating exhaust gas containing PFC, it is less desirable for the PFC decomposition apparatus to stop for one day. This is because an etching apparatus that uses a PFC is operating during maintenance of the decomposition apparatus, and unprocessed PFC is released into the atmosphere.

So far, the catalyst tank has been removed from the reactor as a cartridge type and replaced, but further reduction in maintenance time is desired.

Japanese Patent No. 3237651

  The problem to be solved by the present invention is to perform a process for exchanging the catalyst in a short time in an apparatus for treating a halogen compound using a catalyst.

  In particular, the process of lowering the catalyst temperature, replacing the deteriorated catalyst, and raising the temperature to the predetermined reaction temperature again is to shorten the time. Alternatively, the catalyst is replaced without the process of stopping the heater as described above.

A feature of the present invention for solving the above problems is that a preheater for heating a gas to be processed containing a halogen compound to a predetermined reaction temperature, and the halogen compound contained in the heated gas to be processed containing a catalyst are provided. In a halogen compound processing apparatus comprising a reactor for decomposition and a cooler for cooling the decomposition gas discharged from the reactor,
A means for exchanging the catalyst in the reactor from below is provided, and a cooling water spray device is installed in the preheater.

Alternatively, a feature of the present invention for solving the above problems is that a preheater that heats a gas to be treated containing a halogen compound to a predetermined reaction temperature, a first heating device that heats the preheater from the outside, and a catalyst And a reactor for decomposing the halogen compound contained in the heated gas to be treated, a second heating device for heating the reactor from the outside, and cooling the decomposition gas discharged from the reactor In a halogen compound processing apparatus including a cooler,
Means for exchanging the catalyst in the reactor from below, and a metal pipe between at least one of the preheater and the first heating device and the reactor and the second heating device. It is characterized by installing a cooling pipe made of

  The first heating device and the second heating device may be the same device.

  According to the present invention, the catalyst temperature can be lowered faster than before, the deteriorated catalyst can be replaced, and the temperature can be raised immediately to a predetermined temperature, and the catalytic reaction can be performed without stopping the heater that heats the reactor. The catalyst can be cooled and the catalyst exchanged.

  As a result, the present invention reduces the temperature of the gas to be treated by spraying water into the preheater at the catalyst replacement stage, and rapidly cools the catalyst charged in the reactor at the latter stage of the preheater to replace the catalyst, etc. The apparatus which can shorten the time required for the maintenance of can be provided. In addition, the catalyst replacement process unique to the exhaust gas treatment apparatus using the catalyst can be shortened with low operating costs and maintenance-free.

  Examples of the present invention will be described below.

  FIG. 1 is an example of a system flow to which the present invention is applied. The apparatus comprises at least a preheater, a reactor filled with a catalyst, and a cooler that cools the exhaust gas after decomposition. The to-be-processed gas 1 containing a halogen compound flows into the preheater from the preheater upstream. When exchanging the catalyst in the reactor, for example, water is sprayed from the spray nozzle 2 installed in the preheater to lower the catalyst temperature. The spray nozzle 2 may be installed at the top of the reactor.

  FIG. 2 shows an example in which the preheater and the reactor are integrated. Similarly, the preheater has a spray nozzle. This spray nozzle is desirably installed above the inlet of the gas to be processed 1. The gas 1 to be processed flows from the upstream side of the preheater to the downstream side through the gas inlet 3 in the preheater. The gas 1 to be treated may contain acidic impurities such as HF and HCl. In this case, the corrosion due to the acid can be suppressed by installing the spray nozzle 2 upstream from the gas inlet of the gas to be treated. Further, the heat load is smaller on the upstream side because of heat dissipation.

  FIG. 3 shows an example in which a preheater, a reactor, and a cooler are integrated. Here, it is desirable that the reactor and the cooler be removable. As an example of catalyst replacement, for example, the cooler connected to the reactor and the flange is removed, and the cartridge filled with the catalyst installed in the reactor is extracted from the downstream side. At this time, although the preheater and the heating device of the reactor have not been sufficiently cooled, the catalyst cartridge is cooled, and the catalyst cartridge can be extracted faster than before. In addition, the heating time to a predetermined temperature is shortened even after cartridge replacement.

  FIG. 4 shows an example in which the preheater and the reactor are heated by an integrated heater.

  5 and 6 are examples in the case of automatically operating the cooling water spray. The output controller of the preheater and / or the heating device of the reactor and the water spray controller are linked to each other, and water spray is started when the output from the output controller to the heating device becomes zero. Furthermore, it is desirable to install a timer in the water spray controller so that the water spray stops after a predetermined time. The water spray may be stopped when the catalyst layer temperature or the lower temperature of the catalyst layer reaches a predetermined temperature.

7 to 9 show an example of a method for supplying the gas to be processed to the preheater. For example, when hydrolyzing PFC, H ₂ O is required as a reaction aid. FIG. 7 shows an example in which water or water vapor 4 is added to the gas to be treated 1 containing a halogen compound at the front stage of the preheater. In this method, since water or water vapor 4 may condense before flowing into the preheater, it is desirable to introduce water or water vapor directly into the preheater as shown in FIGS. Although the pipe to the preheater after introducing water or water vapor in FIG. 7 may be kept warm and heated with a ribbon heater or the like, it is wasteful in terms of energy. Since air or oxygen 5 is a gas, it may be introduced directly into the preheater as shown in FIG. 9 in the middle of the piping as shown in FIG. When water is directly introduced as shown in FIG. 9, it is necessary to vaporize in a preheating tank. Therefore, a spiral tube is installed inside the preheater of the water or water vapor inlet, and after sufficiently heated and vaporized there, It is desirable to mix with process gas.

  The installation method of the spray nozzle 2 is arbitrary. A plurality may be installed. Further, it may be arranged in all directions. The nozzle type may be a commonly used one such as a holo cone or a full cone type.

The amount of water added depends on the amount of gas being processed, the gas composition, and the reaction temperature. For example, if the input energy when heating to a predetermined temperature is X [kJ], to decrease from 750 ° C. to 100 ° C., (273.15 + 100) / (273.15 * 750) * X [ H ₂ O that consumes energy of kJ] may be added. When water at 20 ° C. is used, the energy is theoretically consumed by adding (273.15 + 100) / (273.15 * 750) * X / ((100-20) +539) [g]. it can.

FIG. 10 shows an example of a catalytic PFC processing apparatus in a semiconductor manufacturing process and a liquid crystal manufacturing process to which the present invention is applied. The PFC gas 100 is introduced into an etching apparatus 99 in a semiconductor or liquid crystal manufacturing factory. The exhaust gas from the etching apparatus removes SiF ₄ , SiO ₂ , HF and the like contained in the exhaust gas in a spray tower 102 that removes impurities. Air or oxygen 5 is added to the gas to be treated to the gas that has passed through the spray tower and introduced into the preheater 104. Water or steam required for the reaction is introduced directly into the preheater. When water is introduced directly, vaporize in a preheating tank. The water is preferably pure water, but when using city water 10 such as tap water, it is used after removing the metal component deposited as scale through the ion exchange resin 103 or the like. The heating device 6 of the preheater arbitrarily heats the gas to be treated in the range of 400 to 900 ° C. The heated gas to be treated is hydrolyzed in a reactor 105 filled with, for example, a catalyst 7 containing alumina. For example, CF ₄ decomposes into CO ₂ and HF. The reactor heating device keeps or warms the gas to be treated so that the temperature of the gas to be treated does not drop from the set temperature. Since the decomposition product gas that has passed through the catalyst layer has a high temperature, the temperature is lowered by the cooler 106 that can spray water or acidic water. In addition, as a method for cooling the gas to be treated, a general method of water cooling or gas cooling, a heat exchanger, or the like can be used. Then, you may install an acidic waste gas processing tank as needed. FIG. 11 shows an example in which an exhaust gas scrubber is installed. Water is sprayed, and the contact efficiency of the exhaust gas and spray water is improved and mist is removed with the filler 108. The exhaust gas after passing through the cooling chamber is discharged as exhaust gas 17 outside the system by an exhaust facility 109 such as a blower or an ejector. Further, the water that has absorbed the acid gas is also discharged as drainage 20 into the drainage line in the factory by the drainage facility 110. The water used in the cooling chamber 106 and the spray tower 102 may be temporarily collected in the drain tank 111 and drained. Further, in the drainage pump 110, the acid drainage may be recycled to the spray tower 102, the cooling chamber 106, and the exhaust gas cleaning tank 107. When the gas that has passed through the exhaust gas cleaning tank 107 contains mist, particularly acid mist, a mist removing device such as the cyclone 21 may be installed.

  As the exhaust gas cleaning tank, general wet and dry cleaning tanks can be used. Venturi type, shelf type, spray type, etc. can be used as the wet method. The spray method is highly efficient in a method of cleaning using water or an aqueous alkali solution, and exhibits high HF removal performance. A method of bubbling a decomposition product gas in water or an aqueous alkali solution or a method of cleaning using a packed tower may be used. As the dry method, a fixed bed, moving bed, fluidized bed, or bag filter type using an alkaline solid can be used.

  FIG. 11 shows an example in which both water or water vapor 4 and air or oxygen 5 are directly introduced into the preheater 104.

  FIG. 12 shows that instead of spraying water on the preheater, a metal pipe 112 capable of flowing water between the preheater 104, the reactor 105, and the heating device 6 is installed around the preheater and the reactor. A method for accelerating the temperature drop of the catalyst layer will be described. After setting the output of the heating device to zero, water is circulated through the pipe 112. The used water is sent to the drainage line in the equipment. FIG. 12 shows an example in which the outlet of the pipe 112 is connected to the cooling chamber 106.

  Although FIG. 1 to FIG. 12 show various device configurations, these are merely examples, and the components of each device may be used in combination.

  The inflowing impurities are compounds such as Ti, Ta, Si, Al, Cr, Fe, Ni, W, and S, depending on the substrate to be etched and the object to be cleaned. These are removed in an impurity removal step.

The catalyst that can be used in the present invention is a catalyst for PFC decomposition such as hydrolysis or oxidative decomposition. For example, Al, Zn, Ni, Ti, Fe, Sn, Co, Zr, Ce, Si, W, Pt,
A catalyst containing at least one component of Pd can be used. These components exist in the form of oxides, metals, and complex oxides. In particular, a catalyst containing Ni, Zn, Ti, W, Co, and Zr in Al ₂ O ₃ has high decomposition performance. An example is a catalyst comprising Ni and Al oxides. The catalyst contains Al and Ni, which are included in the form of NiO and NiAl ₂ O ₄ . When a part of Al is subjected to X-ray diffraction analysis of the catalyst, a clear diffraction pattern is not observed, but this is probably because it is included as an amorphous state having poor crystallinity. Further, a catalyst added with 1 to 10 wt%, preferably 1 to 5 wt%, of the NiO / Al ₂ O ₃ catalyst using WO ₃ as a metal shows higher performance.

  The amount of water vapor and oxygen to be added is adjusted according to the amount of gas to be processed. Further, when impurities are contained in the gas to be processed, it is necessary to consider them. It may be about 2 to 50 times the theoretical water vapor requirement shown in the PFC decomposition reaction. Preferably 3 to 30 times is good. It is necessary to adjust the number of hydrogen molecules so that the amount of water vapor added is at least equivalent to the F number in the halogen compound to be treated. As a result, F in the compound becomes HF, and F in the decomposition product is in the form of a hydrogen halide that is easily post-treated.

In the decomposition treatment method of the present invention, oxygen in the gas stream containing a halogen compound such as C ₂ F ₆ can be used for the oxidation reaction of CO in the decomposition gas.

The object of the present invention is a halogen compound, and inorganic and organic compounds containing Cl, F, Br, and I. In particular, a PFC containing only fluorine as a halogen has fluorine, carbon, hydrogen, oxygen, sulfur, and nitrogen as component components of the compound, specifically, a compound composed of carbon and fluorine, and a compound composed of carbon, hydrogen and fluorine. , Compounds consisting of carbon, fluorine, hydrogen and oxygen, compounds consisting of carbon, fluorine and oxygen, compounds consisting of sulfur and fluorine, compounds consisting of sulfur, fluorine and oxygen, compounds consisting of nitrogen and fluorine, nitrogen, fluorine and oxygen Is a compound. Examples of compounds include CF ₄ , CHF ₃ , CH ₂ F ₂ , CH ₃ F, C ₂ F ₆ , C ₂ HF ₅ , C ₂ HF ₅ , C ₂ H ₂ F ₄ , C ₂ H ₃ F ₃ , C ₂ H ₄ F ₂ , C ₂ H ₅ F, C ₃ F ₈ , CH ₃ OCF ₂ CF ₃ , C ₄ F ₈ , C ₅ F ₈ , SF ₆ , SO ₂ F ₂ , NF ₃ , etc.

Typical reactions of the hydrolysis reaction of the halogen compound include the following.
CF ₄ + 2H ₂ O → CO ₂ + 4HF (Formula 1)
C ₂ F ₆ + 3H ₂ O → CO + CO ₂ + 6HF (Formula 2)
CHF ₃ + H ₂ O → CO + 3HF (Formula 3)
SF ₆ + 3H ₂ O → SO ₃ + 6HF (Formula 4)
NF ₃ + 3 / 2H ₂ O → NO + 1 / 2O ₂ + 3HF (Formula 5)

In the reactions of (Equation 2) and (Equation 3), CO is generated, but if oxygen is present, CO can be converted to CO ₂ . Further, the CO oxidation catalyst may be installed downstream of the PFC decomposition catalyst, or may be used in the same reaction tube.

  The reaction temperature used in the present invention is preferably about 400 to 850 ° C., but the reaction temperature may be changed depending on the type of compound to be symmetric and the decomposition conditions. When the PFC concentration is high, it may be used at 700 to 850 ° C, and when the concentration is 1% or less, about 600 to 750 ° C is preferable. When used at a high temperature of 800 ° C or higher, the catalyst deteriorates quickly. Also, the corrosion rate of the device material increases rapidly. Conversely, the decomposition rate is low at temperatures below this.

In this example, after the PFC decomposition reaction, the amount of reaction water was changed when the apparatus was stopped,
It is the result of investigating the time required for cooling to 200 ° C. The PFC decomposition reaction is shown in FIG. 13 as a system diagram of a small laboratory-scale apparatus used in this example. This device consists of N ₂ , air,
It consists of a CF ₄ and H ₂ O supply system, a reaction tube, an exhaust gas cleaning tank, and a mist catcher. A reaction tube having an inner diameter of 38.2 mm, an outer diameter of 48.0 mm, and a length of 45.0 mm was used. In addition, it has an Inconel thermocouple protection tube with an outer diameter of 3 mm inside.

About 1243 ml / min of nitrogen, about 125 ml / min of air, and about 6.2 ml / min of CF ₄ were mixed in the previous stage of the reaction tube and introduced into the reaction tube. That is, the dry base CF ₄ concentration (calculated from the nitrogen, air, and CF ₄ flow rates) is about 0.45%. As for H ₂ O, pure water was supplied to the upper part of the reaction tube at about 0.125 ml / min, and was supplied after being vaporized in the preheating layer. The reaction tube was made of Inconel 600 and filled with about 75 ml of a halogen compound decomposition catalyst. The reaction tube was heated from the outside of the reaction tube with an electric furnace, and the catalyst was adjusted to 700 ° C. This decomposition reaction was carried out for about 5 hours, and the relationship between the reaction gas conditions after completion of the test and the catalyst temperature was examined.

  In FIG. 2, when the reaction water is allowed to flow at the same flow rate for 10 minutes after the PFC supply is stopped (hereinafter, the condition name is set to zero), the reaction water amount is increased to 1 ml / min after 10 minutes and 75 minutes are passed. FIG. 14 shows changes in the catalyst layer temperature with time when water is used (hereinafter referred to as water flow of 1 ml / min). At zero water flow, 120 min was required to lower the temperature to 200 ° C., but at a water flow rate of 1 ml / min, the temperature could be lowered to 200 ° C. in 75 min.

  Table 1 shows the time required to reduce the flow rate to 200 ° C. for each flow rate and flow time.

In this example, the test was performed using a large apparatus. The PFC-containing gas containing CF ₄ at 0.5 vol% is 200 L / min. 20 L / min of air was added to this gas and introduced into the preheater. The reaction water was introduced into the preheater at a rate of 20 ml / min and vaporized with a water evaporation tube in the preheater.
After CF ₄ was decomposed with a PFC decomposition catalyst for 2 hours, the supply of PFC was stopped and the decomposition reaction was completed. Ten minutes after stopping the PFC supply, the reaction water supply, the preheater, and the heater that heated the reactor from the outside were stopped. After stopping the heater, 40 ml / min of cooling water was sprayed from the three hollow cone nozzles installed at the top of the preheater. Compared to the case without cooling water spray, the catalyst cooling time could be reduced to about ½.

Reduce PFC in exhaust gas from semiconductor and liquid crystal manufacturing factories, and reduce downtime
PFC gas release to the atmosphere can be suppressed.

It is an apparatus block diagram corresponding to each Example. It is an apparatus block diagram corresponding to each Example. It is an apparatus block diagram corresponding to each Example. It is an apparatus block diagram corresponding to each Example. It is an apparatus block diagram corresponding to each Example. It is an apparatus block diagram corresponding to each Example. It is an apparatus block diagram corresponding to each Example. It is an apparatus block diagram corresponding to each Example. It is an apparatus block diagram corresponding to each Example. It is an apparatus block diagram corresponding to each Example. It is an apparatus block diagram corresponding to each Example. It is an apparatus block diagram corresponding to each Example. It is an apparatus block diagram corresponding to each Example. FIG. 4 is an experimental result diagram of Example 1.

Explanation of symbols

7 ... Catalyst, 8 ... Mist removing device, 9 ... Pure water, 100 ... PFC gas, 104 ... Preheater,
105 ... reactor, 106 ... cooler, 107 ... exhaust gas cleaning tank, 112 ... cooling water piping, 200 ... PFC-containing gas.

Claims (15)

  A preheater that heats a gas to be treated containing a halogen compound to a predetermined reaction temperature, a reactor that contains a catalyst and decomposes the halogen compound contained in the heated gas to be treated, and is discharged from the reactor A halogen compound processing apparatus comprising a cooler for cooling cracked gas, wherein the preheater includes a cooling water spraying apparatus.   The halogen compound processing apparatus according to claim 1, wherein the catalyst in the reactor is configured to be exchangeable from below.   A preheater that heats a gas to be treated containing a halogen compound to a predetermined reaction temperature; and a reactor that is installed downstream of the preheater and decomposes the halogen compound contained in the heated gas to be treated with a catalyst. A halogen compound processing apparatus comprising a cooler for cooling the cracked gas discharged from the reactor, and configured to allow the catalyst in the reactor to be exchanged from below, with cooling water in the preheater A halogen compound processing apparatus comprising a spraying device. The halogen compound processing apparatus according to claim 2 or 3,
The halogen compound processing apparatus, wherein the cooler is disposed below the reactor and is detachably attached to the reactor. The halogen compound processing apparatus according to any one of claims 1 to 4,
A halogen compound processing apparatus comprising a first heating device for heating and / or maintaining the reactor at a predetermined temperature. A preheater that heats a gas to be treated containing a halogen compound to a predetermined reaction temperature, a reactor that contains a catalyst and decomposes the halogen compound contained in the heated gas to be treated, and is discharged from the reactor An apparatus for treating a halogen compound comprising a cooler for cooling cracked gas,
A first heating device for heating and / or maintaining the reactor at a predetermined temperature, and a second heating device for heating the preheater from the outside,
A halogen compound processing apparatus comprising a cooling pipe made of a metal pipe between at least one of the reactor and the first heating apparatus or between the preheater and the second heating apparatus. The halogen compound processing apparatus according to any one of claims 1 to 5,
The said cooling water spraying apparatus has a means to operate | move for a predetermined time, after stopping the preheater or / and the heating apparatus of a reactor, The halogen compound processing apparatus characterized by the above-mentioned. The halogen compound processing apparatus according to any one of claims 1 to 7,
A halogen compound decomposition treatment apparatus having an inlet for water or water vapor in a pipe for introducing a gas to be treated containing the halogen compound into a preheater. The halogen compound processing apparatus according to claim 8,
A halogen compound decomposition treatment apparatus, wherein a pipe for introducing the halogen compound into a preheater has an inlet for air or O ₂ . A halogen compound decomposition treatment apparatus according to any one of claims 1 to 7,
The said preheater has a 1st inlet which introduces the to-be-processed gas containing the said halogen compound, and a 2nd inlet which introduces water or water vapor | steam, The halogen compound decomposition processing apparatus characterized by the above-mentioned. The halogen compound decomposition treatment apparatus according to claim 10,
The preheater halogen compound decomposing apparatus, comprising a third inlet for introducing the air or O _2. The halogen compound decomposition treatment apparatus according to any one of claims 1 to 11,
The halogen compound decomposition treatment apparatus, wherein the halogen compound is exhaust gas from a semiconductor and / or liquid crystal manufacturing apparatus or factory.   12. The halogen compound decomposition treatment apparatus according to claim 1, wherein the halogen compound contains PFC (perfluoro compound) as a main component.   14. The halogen compound decomposition treatment apparatus according to claim 1, further comprising an impurity removal means for removing impurities in the gas to be treated by spraying water on the upstream side of the preheater. Halogen compound decomposition treatment equipment. The halogen compound decomposition treatment apparatus according to claim 14,
The halogen compound processing apparatus, wherein the impurity is a silicon-containing compound.

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