JPH02201160A - Method and instrument for measuring concentration of gaseous fluorine-containing component - Google Patents

Abstract

PURPOSE:To rapidly detect the components particularly in an excimer laser by noticing that gases are generated quantitatively by reaction with gaseous fluorine and various compds. or simple substances and converting the gaseous fluorine which has high toxicity and is active to other gases which are easy to handle and detecting the concn. thereof by using various detectors. CONSTITUTION:The gaseous sample contg. fluorine passes through respectively separate two packed beds A, B and are introduced to the respective detectors, by which the concns. of the gaseous components are detected at the time of measuring the components in the above-mentioned gas. The packed bed A is constituted of the packed bed contg. a material which converts the gaseous fluorine to carbon dioxide or gaseous metal fluoride and the packed bed B is constituted of the packed bed contg. a material which is used in the packed bed A but converts to the gas different from the gas converting of the packed bed A. More specifically, the gaseous sample passes dividedly through the packed bed 3 of No. 1 and the packed bed 7 of No. 2. Sodium bicarbonate or the like is packed in the bed 3 and the powder of Si metal or the like in the bed 7.

Description

Detailed Description of the Invention [Industrial Application Field 1] The present invention relates to a method and apparatus for measuring the concentration of fluorine and other components in a fluorine-containing gas, and particularly to a method and apparatus for measuring the concentration of fluorine and other components in an excimer gas laser. This invention relates to a concentration measuring device.

[Prior Art] Conventionally, various methods have been known for analyzing the fluorine concentration in gas, but two methods are known: a wet method and a dry method.

As a wet method, a method is known in which chlorine is oxidized by passing fluorine gas into the IJLiC1 solution, and the chlorine is analyzed using an electrode.

[S, Kaye, M, Griggs: Anal
, Chew, , 40.221? , (1968>
] Also, as a dry method,! 21 After removing HF in the sample gas using a NaF pellet, it is reacted with fluorine through a NaCl layer, the generated chlorine gas is absorbed into a NaOH solution, and the generated hypochlorous acid is determined by iodometric titration [A, M, G. Macdonald
al, 'Fluoline', Encyclopeded
ia of Industrial Chemical
Analisis, Vol. 13. New York-L
or+don-5ydney-Tronto, 197
1], 131 Gas chromatograph method, a method in which fluorine gas is directly analyzed using a special material such as nickel for the part that comes into contact with the sample, and a thermoconductivity cell coated with PTFE [M, M , 5hahln, etc.
al,, Anal, Chem, 35,465. (19
63)] etc. are known.

[Problems to be Solved by the Invention] However, in the above method, it is necessary to completely absorb the fluorine gas into the liquid in the fil, so it is difficult to set engineering conditions at the time of barking and adjust Pl + at the time of analysis. etc., the equipment and operation become complicated, and in (2), the reaction spans two stages, making the equipment complicated, making it difficult to increase accuracy (, in +31,
The need to cover the thermal conductivity cell reduces sensitivity;
There are various problems such as the expensive material of the device.

Therefore, in order to solve the problems of the conventional method, the present applicant proposed a method for analyzing the fluorine concentration in gas very quickly and accurately using a simple device. March 31st), the title of the invention is ``Fluorine concentration measuring method and device'', in which fluorine in a gas is passed through a packed bed containing an alkali metal compound or an alkaline earth metal compound to convert it into oxygen. We proposed a method and device for measuring the fluorine concentration in gas and knowing the fluorine concentration in gas. Subsequently, the present inventors further investigated methods of converting fluorine into other gases, and found that by converting fluorine in a gas into another gas and measuring its concentration, the fluorine concentration could be measured indirectly. Regarding the method of
The present invention was arrived at through extensive research into compounds or simple substances.

[Means for Solving the Problems] The method of the present invention was developed by focusing on the fact that gas is quantitatively generated through the reaction of fluorine gas with various compounds or simple substances, and this makes it possible to reduce toxicity. After converting the large and active fluorine gas into another gas that is easy to handle, its components and concentrations are detected and measured using various detectors.

That is, the present invention provides a method for measuring the concentration of a component in a sample gas containing at least fluorine, in which the gas is separated into the following two packed layers: Packed layer A; a substance that converts fluorine gas into carbon dioxide or metal fluoride gas; Filled layer containing.

Packed Bed B2 A packed bed containing a substance used in Packed Bed A that converts into a gas different from that of Packed Bed A, or a substance that fixes fluorine gas to the packed bed.

Among them, only the filling layer A, or the filling layer 711A, and the filling layer B
A method for measuring the concentration of a fluorine-containing gas component, characterized in that the gas component is passed through two steps separately, guided to a detector, and the concentration of each gas component is measured, a packed bed A and a detection section, or a packed bed A, a packed bed. The present invention is a device for measuring the concentration of a fluorine-containing gas component, which is characterized by comprising a layer B and a detection section, and among the above-mentioned devices, it is particularly applicable to a device for measuring the concentration of a fluorine-containing gas component in an excimer gas laser.

The packed bed A of the present invention, that is, the substance that converts fluorine gas into another gas, first includes a compound that converts it into carbon dioxide.

These compounds include carbonates or bicarbonates of alkali metals or alkaline earth metals, such as soda carbonate, sodium bicarbonate, calcium carbonate, calcium bicarbonate, potassium carbonate, potassium carbonate, lithium carbonate, lithium bicarbonate, barium carbonate, barium bicarbonate, magnesium carbonate,
Examples include magnesium bicarbonate.

An example of these chemical reaction formulas is shown in (a).

F2 +C&CD3- NaF2 +CO2+1/2
02 ”' (4) Through this reaction, fluorine in the gas, 1
It is quantitatively converted into carbon dioxide at a ratio of 1 mole of carbon dioxide per mole. In the pond compounds, the proportion of fluorine converted to carbon dioxide is the same.

The above reaction proceeds rapidly by keeping the packed bed at a temperature of 100° C. or higher, but in this case, in order to increase the reaction activity of the packed bed, it is necessary to use particles with a particle size as small as possible.

Next, substances that convert fluorine into other gases include simple substances, and in this case, a compound of fluorine and the simple substance is formed through a reaction. An example of a chemical reaction formula is as shown below.

2F2 +Si → SiF 4...color) In this case, the simple substances are Si, Ge, P, and Sb.

Examples include Se, Te, W, Mo, V, and B.

As mentioned above, fluoride gas is generated at a ratio of 1 mole per 2 moles of fluorine gas.Si, Ge, etc. generate fluoride gas at a ratio of 2 moles per 3 moles of fluorine gas. Examples of substances that generate fluoride gas include B, and examples that generate fluoride gas at a ratio of 2 moles to 5 moles of fluorine gas include P, Si, Sb, etc., and 1 mole to 3 moles of fluorine gas.
Among those that generate fluoride gas in molar proportions, Se
, Te, W, Mo, etc., respectively.

In the above-mentioned packed bed, the temperature is preferably maintained at 100°C or higher, and in order to increase the reaction activity of the single substance used in the reaction, it is preferable to use powder with a fine particle size.A detailed explanation of the apparatus will be given later. , In the attached FIG. 1, the packed layer A filled with these materials is indicated by No. 1 Filled layer ■.

As a method for measuring the concentration of oxygen and other components in the gas that has passed through the packed bed A.

Gas chromatography or infrared absorption spectrum (
Hereinafter, it will be abbreviated as LR.

The gas supplied to the detector consists of other gas components stoichiometrically corresponding to the amount of fluorine and other components originally contained in the gas. Since the gas has been converted to a safe gas, a conventional type of gas chromatography or IR measurement cell can be used if no other corrosive gases are present.

The present invention targets gases that do not contain corrosive gases to the detection part other than fluorine and gases that do not react with the packed bed, and are applicable to ordinary types of gas chromatography or! Analysis is performed using an R measurement cell.

When measuring by gas chromatography, if a gas chromatography packing material with known retention times for the gas to be converted and other components is used, the concentration of each component can be measured by setting the analysis conditions to the required values. can do.

In particular, in excimer laser gas, Kr, Xe
Although it is necessary to measure the concentration of oxygen, the above analysis can be performed by using a molded porous polymer of polystyrene-divinylbenzene copolymer.

On the other hand, in the case of IR, by plotting the concentration of generated gas and the absorption value of infrared rays in advance, it is possible to know the concentration of fluorine gas initially contained. In the case of IH,
It is difficult to know the concentration of all gas components, and it is necessary that the components of other gases do not vary greatly with respect to the generated gas. Also, the relationship between concentration and absorption value is close to a straight line in the low concentration range of a few percent or less, so when analyzing a high concentration gas, the gas must be diluted to a known dilution ratio. There is a need.

If the gas does not contain any gas generated in the packed bed A, the agitation value from the value measured by the above method will be the fluorine concentration as it is, and the packed bed only needs to be the packed bed A.
An apparatus consisting only of the above-mentioned packed bed and a detection section consisting of gas chromatography or IR may be sufficient.

On the other hand, if the same gas as the gas converted by packed bed A is contained in the gas to be measured from the beginning, in order to measure the fluorine concentration in the gas, the concentration of the gas originally present in the gas must be determined in advance. It is necessary to know that if a gas containing fluorine is directly introduced into a gas chromatography system, the detection part may be ruptured, so the fluorine gas should be
fluorine is converted into a gas different from the gas to be converted, or by fixing fluorine in a packed bed using solid fluoride and the compound 7 by reaction, and then introducing it into a gas chromatography or IR cell. The concentration of the gas contained therein can be measured.

As a filler that generates a gas different from the gas converted in packed bed A, one of the same substances as packed bed A can be used; in this case, the materials in packed bed A and packed bed B are different. In this case, only one filling layer B is required, which corresponds to No. 2 filling layer ■ in FIG.

On the other hand, fixing methods include directly reacting with fluorine to fix it as a solid fluoride, and fixing it as a fluoride by forming a fluoride gas and then providing a packed layer of an alkali metal or alkaline earth compound. There are two possible cases.

The element to be reacted with fluorine may be any element that produces a compound by reaction with fluorine.
Ge, P, Sb, Te, S, W, No, V, Fe, Cr
, MnCo, Zn, Sn, Pb, TI, Zr, Se, etc.

In this case, Fe, Cr, Mn, Co, Zn, Ti, Zr
, Sn, Pb, etc. react with fluorine to form FeF3,
Since solid fluoride of CrF3 and MoF3-kasa is produced, it is immobilized as it is.

In this case as well, the filled bed B is No. in FIG.

There will be only 2 filled layers ■.

On the other hand, Si, Ge, P, Sb, S, Se, Te, W, M
Since o, v, etc. produce gaseous fluoride by reaction with fluorine, the following reaction is used in this case.

2 F2 +Sl −* SiF ,... mountain)S
iF4 + 2Ca(OH)z →2CaF2 +
5102 +21i20-icl In the reaction of the above formula (bl), each element has a different valence, so the valence of the fluoride differs somewhat, but the form of the reaction is the same.

In the reaction of one formula (C, l), the alkali metal and alkaline earth metal compounds corresponding to calcium hydroxide include alkaline earth metal and alkali metal hydroxides (for example, lithium hydroxide, sodium hydroxide, hydroxide potassium, magnesium hydroxide, strontium hydroxide,
barium hydroxide, etc.), oxides (e.g. lithium oxide, sodium oxide, potassium oxide, calcium oxide).

magnesium oxide, barium oxide, etc.), carbonates (e.g. lithium carbonate, sodium carbonate, potassium carbonate, magnesium carbonate, calcium carbonate, strontium carbonate, barium carbonate, etc.), bicarbonates, sulfates, nitrates or soda lime (calcium hydroxide, (mixtures of calcium oxide, sodium hydroxide, water, etc.) can be used, but soda lime, a mixture of calcium hydroxide, calcium oxide, and sodium hydroxide, can be used in particular because it generates quantitative oxygen gas. Preferably, the compound used is in the form of fine particles.

Here, in FIG. 1, the layers in which the reactions of (mountain) and (C1) occur, that is, the packed bed B, are NO, 2 packed layers
There will be 3 packed layers■.

In this case as well, the column can be used at room temperature, but it is preferably kept at 1009C or higher using a heater or the like.

In this way, the concentration of fluorine or fluorine and other components in a gas can be rapidly determined by converting the fluorine in the gas into another gas and measuring the concentration of the gas by gas chromatography or IH. That is,
It's now possible.

This method can be applied to various gases containing fluorine, and its detection range is very wide, from several PI) to several tens of percent for fluorine, and from several pp- to several tens of percent for other components. It covers a wide range. A device to which this method is applied is shown in FIG.

Accordingly, the measuring method of this apparatus will be explained with reference to FIG. This figure shows the case where gas chromatography is used as the measuring device.

First, open the valve ■■■■, and use a flow meter to flow a constant flow rate of measurement gas into the No. 1 packed bed ■ for several tens of seconds to several minutes, sample the gas into the sample introducer By analyzing p+
(Fluorine gas concentration + No,! Gas concentration of the same component as the gas converted in the packed bed ■) can be measured. On the other hand, in order to check whether the gas contains a gas with the same components as the gas converted in the N011 packed bed ■, open the valve for ■■ [phase] ■ and inject the measurement gas at the same flow rate. P2 (
It is possible to measure the gas concentration of the same component as the gas converted in the NO, l packed bed (2).

In this case, the capacity of each component is expressed by retention time and peak area in gas chromatography, so
If the retention time of each component is measured in advance and the relationship between the peak area and the component concentration is determined from a calibration curve, its concentration can be immediately known.

Regarding the fluorine concentration, which is a problem in this, if we consider the case of converting it to carbon dioxide, as shown in equation (5), 1 mole of F2 gas is converted to 1 mole of CO2 gas, so the original The fluorine gas concentration is n (pt I)
2) can be calculated.

Here, D is a correction coefficient.

In the case of IH analysis, the equipment is almost the same; an IR cell is installed instead of the sample introducer, and after the inside of the cell has been completely replaced by the sample gas, it can be separated from the main equipment to measure infrared absorption. By making it possible to attach the IR cell or by incorporating the IR cell into an infrared measuring device, the fluorine concentration can be measured on-time.

This device is particularly effective as a fluorine concentration analysis needle for excimer laser gas. Excimer lasers may experience a drop in output during operation, but this is due to the concentration of fluorine in the gas and the Kr content as a component.
This is thought to be due to a decrease in the , Xe or Ar concentration, and the generation of oxygen and other impurity gases.

Removal of impurities can be performed by adsorption or cold trap methods, but monitoring of fluorine concentration in the laser gas is
Currently, this analysis is not performed due to the complexity of the analysis and the difficulty of handling.9 Therefore, it is necessary to understand whether the decrease in laser output is due to the generation of impurity gas or the decrease in the concentration of fluorine gas. I couldn't do it.

According to this device using gas chromatography, in addition to the fluorine concentration, its important components such as r, Xe, and Ar
It is possible to analyze the concentration of rare gases such as
By solving this problem, efficient laser oscillation becomes possible.

Furthermore, the method of analyzing gas component concentration using gas chromatography of the present invention is applicable to the fluorine concentration measuring device using an oxygen sensor disclosed in Japanese Patent Application No. 1988-79088, and the method of the present invention! It can also be used in conjunction with the method for measuring fluorine concentration using R, and both can be used properly depending on the purpose.

[Examples] Hereinafter, the present invention will be explained in detail with reference to Examples, but the present invention is not limited to these Examples.

Example 1 Using only the No. 1 packed bed (2) of the apparatus shown in Fig. 1, a helium gas containing known concentrations of fluorine gas and Kr was used to generate a flow rate of 50 cc/s in the No. 1 packed bed (2).
A calibration curve of the relationship between peak area and concentration (volχ) is created by sampling with a sample introducer at a flow rate of in for 30 seconds or more.

At this time, as a packing material for the gas chromatography column, Borabac Q (Wate
rs), the column was 2.3φ x 1m, the column temperature was 30℃, and the carrier gas was helium with a flow rate of 25℃.
I went as cc/Otori in. The holding time at this time is 02
: 0.24 inch, CO2: 0.651 inch.

Next, using fluorine gas and helium gas whose Kr concentration was adjusted as shown in Table 1, the carrier gas flow rate was kept the same, and the concentration of each component was read from the peak area at that time.

N011 packed bed for converting fluorine to carbon dioxide■
A Monel 8φ x 100L column was filled with 10g of soda carbonate. The components and concentrations of the sample gas and the components and concentrations of the measured gases are shown in Table 1.

As can be seen from the results, the concentration measurement results of each component by gas chromatography were in good agreement with the introduced gas, and it was found that there was no problem in practical use in this case.

(Conversion factor n; 1) Example 2 Using the same apparatus as in Example 1, similar measurements were carried out on gases consisting of A, Ne, and fluorine with known concentrations. Ga5kuropack 54 (manufactured by Gascro Kogyo Co., Ltd.), which is a porous polymer of polystyrene-divinylbenzene copolymer, was used as the packing material, the column was 3φ x 6m, and the column temperature was -72°C (dry ice-acetone bath).
The carrier gas is helium and the flow rate is 30CC/meal.
It was set to

゛The components and concentrations of the sample gas and the components and concentrations of the measured gases are shown in Table 2.

(Conversion coefficient n=1) Table 2 Example 3 Using the apparatus shown in Figure 1, r + 5.00volχ
, Fluorine: 0.200volX, CO2: 0.05
Using a sample gas whose components were adjusted to 0volX, He: 94.75χ, the component concentration was analyzed.

The temperature of No. 1 packed bed ■, No. 2 packed bed ■, and No. 3 packed bed ■ was set at 150°C, and sodium bicarbonate was added to ■, soda lime was added to ■, and Sl metal powder was added to ■, respectively. Made of SuS with fluorine passivation 1
It was used after being packed into a 0φxioot column.

The conditions for analysis by gas chromatography were the same as in Example 1.

No. The analysis result when passing only 1 packed bed ■ is as follows.
: 5.08vol! , CO2: 0.255vol
On the other hand, the analysis result after passing through ■■ is r:
4.96volχ, CO2: 0.053volχ. (Conversion coefficient n-1) From this result, the concentration of each component is calculated as follows: Kr: 5.08volX, CO2:
0.053 volχ, fluorine: 0.202 vol
χ, He: 94.67 volχ, indicating that the fluorine concentration can be measured without any problem even in a system containing CO2.

[Effects of the Invention] According to the present invention, using a simple method, operation and device,
The concentration of fluorine, nitrogen, Ar, Ne, etc. in the gas can be measured quickly and accurately, and in particular, the concentration of each component in the excimer laser gas can be quickly measured, so the composition in the gas can be adjusted to the optimum value. This is a very effective method because it can be controlled to achieve stable laser oscillation.

[Brief explanation of the drawing]

Figure 1 shows a schematic diagram of the device of the present invention, where 0 is a layer filled with silica gel to adsorb and remove moisture. This is a sample introducer for chromatography analysis. ■・・・・・・No, 1 packed layer ■・・・・・・N
o, 2 packed beds ■・・・No, 3 packed beds [Phase]
・・・・・・Sample introducer; Part 2 system

Claims (3)

[Claims] (1) In a method for measuring the concentration of a component in a sample gas containing at least fluorine, the gas is divided into the following two packed layers: Filled layer A: Contains a substance that converts fluorine gas into carbon dioxide or metal fluoride gas Filled layer. Packed bed B: A packed bed containing a substance used in the packed bed A that converts into a gas different from that of the packed bed A, or a substance that fixes fluorine gas to the packed bed. Among these, the concentration of fluorine-containing gas components is characterized in that only the packed bed A, or the two steps of the packed bed A and the packed bed B are passed through each separately and guided to a detector to measure the concentration of each gas component. Measuring method. (2) In an apparatus for measuring the concentration of a component in a sample gas containing at least fluorine, the following packed bed Packed bed A: A packed bed containing a substance that converts fluorine gas into carbon dioxide or metal fluoride gas. Packed bed B: A packed bed containing a substance used in the packed bed A that converts into a gas different from that of the packed bed A, or a substance that fixes fluorine gas to the packed bed. and a fluorine-containing gas component concentration measuring device comprising a packed bed A and a detection part, or a packed bed A, a packed bed B, and a detection part, of the detection part. (3) A device for measuring the concentration of a component in a sample gas containing at least fluorine, characterized in that it is configured as in claim (2).