JPH0797106B2 - Fluorine-containing gas component concentration measuring method and apparatus - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for measuring the concentration of fluorine and other components in a gas containing fluorine and an apparatus therefor, and particularly fluorine and other components in an excimer gas laser. The present invention relates to a concentration measuring device.

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

Known wet methods include (1) a method in which fluorine gas is passed through a LiCl solution to oxidize chlorine, and this is analyzed by an electrode.

[S.Kaye, M.Griggs: Anal.Chem., 40,2217, (1968)] Further, as a dry method, (2) after removing HF in the sample gas with NaF pellets, fluorine was passed through the NaCl layer. React, absorb the generated chlorine gas in NaOH solution,
Method for determining the generated hypozinc acid by iodometric titration [A.
MGMacdonald et al, “Fluoline”, Encyclopedia of In
dustrial Chemcal Analsis, vol.13, Newyork-London-S
ydney-Tronto, 1970], (3) As a gas chromatographic method, a special material such as nickel is used in the part where the sample contacts, and the thermoconductivity cell is coated with PTFE and the fluorine gas is directly analyzed. [E.Rudzitis: Anal.Chem.3
5,465, (1963)], etc. are known.

[Problems to be Solved by the Invention] However, in the above method, in (1), since it is necessary to completely absorb the fluorine gas into the liquid, setting of engineering conditions during blowing and adjustment of PH during analysis Etc., the apparatus and the operation are complicated, and the reaction is complicated in two steps in (2), the accuracy is difficult to increase, and in (3), it is necessary to coat the thermal conductivity cell. There are various problems such as a decrease in sensitivity and an expensive material for the device.

Therefore, the present applicant has proposed a method for analyzing the fluorine concentration in a gas very quickly and accurately by using a simple device for solving the problems of the conventional method, as disclosed in Japanese Patent Application No. 63-79088 (filed on 63 (March 31, 2012), in the title of the invention "Method and apparatus for measuring fluorine concentration", the concentration of fluorine in gas is converted into oxygen after passing through a packed bed containing an alkali metal or alkaline earth metal compound. We have proposed a method and apparatus for measuring fluorine and knowing the fluorine concentration in gas. After that, as a result of further study by the present inventors, as a method capable of detecting not only the fluorine concentration in the gas but also other components at the same time, the gas obtained by converting fluorine into oxygen by the method described in the previous application was gasified. The present invention has been achieved by studying a method of analyzing by chromatography.

[Means for Solving Problems] The method of the present invention was made paying attention to the fact that oxygen gas is quantitatively generated by a reaction with an alkali compound such as fluorine gas Ca (OH) ₂ . With this method, fluorine gas, which has a large toxin and is active, is converted into oxygen that is easy to handle, and then each component is separated and measured by gas chromatography.

That is, the present invention is a method for measuring the concentration of components in a sample gas containing fluorine, etc., wherein the gas is a hydroxide, oxide, carbonate of an alkali metal or alkaline earth metal,
Passing a packed bed containing bicarbonate or soda lime,
A step of passing through a packed bed containing an element which reacts with fluorine to form a compound or the packed bed and two steps containing a hydroxide, oxide, carbonate, bicarbonate or soda lime of an alkali metal or alkaline earth metal; The gas that has passed through the step of passing the packed bed consisting of layers is introduced into a detector composed of gas chromatography, respectively, and the concentration of the gas component is measured, a fluorine-containing gas component concentration measuring method, alkali metal or alkaline earth. A packed layer containing a hydroxide, oxide, carbonate, bicarbonate or soda lime of a group metal, a packed layer containing an element that reacts with fluorine to form a compound, or the packed layer and an alkali metal or an alkaline earth metal. Packing layer consisting of two layers containing hydroxide, oxide, carbonate, bicarbonate or soda lime, and a sensing part consisting of gas chromatography Fluorinated gas component concentration measuring apparatus characterized by being more configuration, and a fluorine-containing gas component concentration measuring apparatus of the excimer gas laser constituted by the apparatus. Further, after passing the gas of the present invention through a packed layer containing a hydroxide, oxide, carbonate, bicarbonate or soda lime of an alkali metal or an alkaline earth metal, the gas component concentration is measured by a similar detector. A method for detecting, comprising a packed bed containing a hydroxide, oxide, carbonate, bicarbonate or soda lime of an alkali metal or an alkaline earth metal, and a detector comprising a gas chromatography. Fluorine gas component concentration measuring device,
The apparatus for measuring the concentration of fluorine-containing gas components in an excimer gas laser constituted by the above apparatus is a method and apparatus used for a gas containing no oxygen component.

Briefly explaining the principle of the present invention by a chemical reaction formula,
First, the reaction between fluorine in the gas and calcium hydroxide is represented by the following formula (a).

F ₂ + Ca (OH) ₂ → CaF ₂ + H ₂ O + 1/2 O ₂ (a) By this reaction, with respect to fluorine and 2 atomic equivalents in the gas,
It is quantitatively converted into oxygen at a ratio of one atomic equivalent of oxygen. The above reaction is a reaction in the case of an alkaline earth metal. Alkali metal has a slightly different reaction coefficient, but the reaction mode is the same and the amount of oxygen generated is also the same.

In the above reaction, as the alkali metal and alkaline earth metal compounds corresponding to calcium hydroxide, hydroxides of alkaline earth metals and alkali metals (for example, lithium hydroxide, sodium hydroxide, potassium hydroxide, magnesium hydroxide, water Strontium oxide, barium hydroxide, etc., oxides (eg lithium oxide, sodium oxide,
Use potassium oxide, calcium oxide, magnesium oxide, barium oxide, etc.), carbonates (eg lithium carbonate, sodium carbonate, potassium carbonate, magnesium carbonate, calcium carbonate strontium carbonate, barium carbonate etc.), bicarbonate or soda lime etc. But you can
Particularly, a mixture of calcium hydroxide, calcium oxide and sodium hydroxide, which is called soda lime, is preferable from the viewpoint of quantitative generation of oxygen gas. Although a description of the device will be given later, the layer filled with these materials is shown as No. 1 filled layer in FIG.

Although the packed bed can be used even at room temperature, it is more preferably kept at 100 ° C. or higher in consideration of efficiency and the like.

On the other hand, gas chromatography is used as a method for measuring the oxygen concentration and the concentrations of other components in the gas that has passed through the No. 1 packed bed.

The gas supplied to gas chromatography is water and oxygen that stoichiometrically correspond to the amount of fluorine, and other components that were originally included in the gas, but the fluorine gas that adversely affects the detection unit. Since it has been converted to safe oxygen, normal types of gas chromatography can be used without other corrosive gases. In addition to fluorine, the present invention targets a gas that does not contain a corrosive gas for a gas chromatography detection part and a gas that does not react with a packed bed, and analyzes by a normal type gas chromatography.

Since fluorine quantitatively generates oxygen in the packed bed as described above, the fluorine concentration can be measured if the oxygen concentration initially contained is known.

If the gas contains no oxygen at all, the converted value from the value measured by the above method will be the fluorine concentration as it is and the packed bed will only need to be the No. 1 packed bed, so it will consist of the packed bed and gas chromatography. A device with only the detector is sufficient.

It is also necessary to analyze the concentration of components other than oxygen converted from fluorine by gas chromatography. In this case, a packed bed for a gas chromatography column corresponding to the components of the gas to be analyzed may be used and the analysis conditions may be used. Particularly, in the excimer laser gas, it is necessary to measure the concentrations of Kr, Xe, Ar, and oxygen, but the above analysis can be performed by using a polystyrene-divinylbenzene copolymer type porous polymer molding.

Further, based on the principle of the present invention, in order to measure the concentration of fluorine in the gas, it is necessary to previously know the concentration of oxygen existing in the gas, and the gas containing fluorine can be directly analyzed by gas chromatography. Since the detection part may be destroyed if it is introduced into, the oxygen concentration contained in the gas from the beginning is measured by once fixing fluorine to the packed bed by the following reaction and then introducing it into gas chromatography. can do.

As a fixing method, a case of directly reacting with fluorine to fix as a solid fluoride, or a case of using a fluoride gas and then N
o.1 There are two possible ways of fixing the fluorine as a packed bed made of the same material as that used for the packed bed later.

The element to be reacted with fluorine may be any element as long as it produces a compound by the reaction with fluorine, such as Si, Ge,
P, Sb, Te, S, W, Mo, V, Fe, Cr, Mn, Co, Zn, Sn, Pb, Ti, Zr, Se and the like can be mentioned.

In this case, Fe, Cr, Mn, Co, Zn, Ti, Zr, Sn, Pb, etc. react with fluorine to produce solid fluorides such as FeF ₃ , CrF ₃ , MnF _4, ... Be converted. In this case, the filling layer is only the No. 2 filling layer in FIG.

On the other hand, Si, Ge, P, Sb, S, Se, Te, W, Mo, V, etc. generate a gaseous fluoride by reaction with fluorine, and therefore the following reaction is used in this case.

2F ₂ + Si → SiF ₄ (b) SiF ₄ + 2Ca (OH) ₂ → 2CaF ₂ + SiO ₂ + 2H ₂ O (c) In the reaction of the above formula (b), the valence differs depending on each element, so fluoride The valences of are slightly different, but the reaction forms are the same.

On the other hand, in the reaction of the formula (c), the compound used for the reaction with the fluoride gas is exactly the same as the compound used in the formula (a).

Here, the layers for carrying out the reactions (b) and (c) are the No. 2 filled layer and the No. 3 filled layer in FIG. 1, respectively.

In this case also, the column can be used at room temperature, but it is preferable to keep it at 100 ° C. or higher with a heater or the like.

As described above, the method of converting fluorine in gas to oxygen and measuring the oxygen concentration by gas chromatography has made it possible to rapidly measure the concentration of fluorine and other components in the gas.

This method can be applied to various gases including fluorine, and its detection range is also very wide, from a few ppm to a few tens of percent as F _{2 in} the case of fluorine, and a few ppm to a few tens percent for other components as well. It extends to. The device which applied this method is the first
It becomes like the figure.

Therefore, the measuring method of this apparatus will be described with reference to FIG. First open the valve, flow a measurement gas at a constant flow rate for several tens of seconds to several minutes through the No. 1 packed bed, sample the gas in the sample introducer, and then analyze by gas chromatography. , P ₁ (fluorine gas concentration + oxygen gas concentration) can be measured.

On the other hand, in order to check whether or not oxygen is contained in the gas, the valve of is opened and the gas for measurement is flowed through the No. 2 packed bed and the NO.3 packed bed at the same flow rate to obtain p ₂ (oxygen (Gas concentration) can be measured. In this case, the capacity of each component is represented by retention time and peak area by gas chromatography, so by measuring the retention time of each component in advance and determining the relationship between the peak area and the component concentration from the calibration curve, You can know their concentration in them.

Considering the fluorine concentration which is a problem in this,
As can be seen from the equation (a), 1 mol of F ₂ gas is converted to 1/2 mol of O ₂ gas, so the original fluorine gas concentration is considered to be twice the oxygen gas concentration, and 2n (p ₁ − It can be calculated by p ₂ ). Here, n is a correction coefficient.

This device is particularly effective as a fluorine concentration analyzer for excimer laser gas. The output of the excimer laser may decrease during the operation of the device, which is caused by the concentration of fluorine in the gas and Kr and Xe contained as components.
It is also considered to be due to a decrease in Ar concentration and generation of oxygen and other impurity gases.

Impurities can be removed by adsorption method or cold trap method, but the concentration of fluorine in the laser gas can be monitored.
At present, it has not been performed due to the complexity of the analysis and the difficulty of handling. Therefore, it was not possible to determine whether the decrease in laser output was due to the generation of impurity gas or the decrease in fluorine gas concentration.

With this device, it is possible to analyze not only the concentration of fluorine but also the concentrations of the noble gases such as Kr, Xe, and Ar, which are important components, all at once. Oscillation is possible.

Further, the present invention can be used in combination with a device for measuring the fluorine concentration by an oxygen sensor disclosed in Japanese Patent Application No. 63-79088, and both can be used properly depending on the purpose.

[Examples] Hereinafter, examples will be described in more detail, but the present invention is not limited to these examples.

Example 1 In the apparatus shown in FIG. 1, only the No. 1 packed bed was used, and a helium gas containing a known concentration of oxygen gas and Kr was used to flow through the No. 1 packed bed at a flow rate of 50 cc / min. Sampling for 30 seconds or more at the sample introducer and prepare a calibration curve for the relationship between peak area and concentration (vol%).

At this time, POLAPACK Q (manufactured by Waters), which is a porous polymer of polystyrene-divinylbenzene copolymer, was used as the packing layer of the column for gas chromatography.
The column was 3φ × 3 m, the column temperature was 30 ° C., the carrier gas was helium, and the flow rate was 50 cc / min.

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

The concentration of fluorine was obtained by doubling the read concentration of oxygen. Soda lime was used as the No. 1 packed bed for converting fluorine to oxygen. Table 1 shows the components and concentrations of the sample gas and the measured components and concentrations of the gas.

As can be seen from these results, the results of measuring the concentrations of the respective components by gas chromatography were in good agreement with the introduced gas, and in this case it was found that there was no problem in practice.

Example 2 Using the same apparatus as in Example 1, the same measurement was performed using a gas containing Ar, Ne and fluorine with a known concentration. At this time, Gaskuropack 54 (manufactured by Gaskuro Industrial Co., Ltd.), which is a porous polymer of polystyrene-divinylbenzene copolymer, was used as the packing layer of the column for gas chromatography, the column was 3φ × 6 m, and the column temperature was −72. ℃
(Dry ice-acetone bath), the carrier gas was helium, and the flow rate was set to 30 cc / min.

Table 2 shows the components and concentrations of the sample gas and the measured components and concentrations of the gas.

Example 3 Using the apparatus shown in FIG. 1, Kr: 5.00 vol%, fluorine: 0.200
The concentration of each component was analyzed using a gas in which the components of the sample gas were adjusted so that vol% 3 oxygen: 0.050 vol% and He: 94.75%.

The temperatures of the No. 1 packed bed, the No. 2 packed bed, and the No. 3 packed bed were set to 150 ° C., soda lime was filled in, and Si metal powder was filled in.

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

The analysis result when only the No. 1 packed bed was passed was Kr: 5.05vol.
%, Oxygen: 0.143 vol%, and the analysis result after passing one side was Kr: 4.96 vol%, oxygen: 0.047 vol%.

When the concentration of each component was obtained from this result, Kr: 5.01vol
%, Oxygen: 0.047vol%, fluorine: 0.192vol%, He: 94.75vo
It became 1%, and it was found that the fluorine concentration can be measured without problems even in a system containing oxygen.

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

[Brief description of drawings]

FIG. 1 shows a schematic diagram of the apparatus of the present invention, where is a layer filled with silica gel for adsorbing and removing water, and is a fixed amount of sample gas, and analyzed by direct gas chromatography. It is a sample introduction device for doing. ...... No.1 packed bed ...... No.2 packed bed ...... No.3 packed bed ...... Sample introducer

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication H01S 3/225

Claims (6)

[Claims] 1. A method for measuring the concentration of a component in a sample gas containing fluorine or the like, wherein the gas is a hydroxide, oxide, carbonate, bicarbonate or soda lime of an alkali metal or alkaline earth metal. A step of passing a packed layer containing the same, a step of passing a packed layer containing an element which reacts with fluorine to form a compound, or a hydroxide, oxide, carbonate or bicarbonate of the packed layer and an alkali metal or alkaline earth metal. Alternatively, the gas that has passed through the process of passing through a packed bed consisting of two layers containing soda lime is introduced into a detector consisting of gas chromatography, and the concentration of the gas component is measured, and the concentration of the fluorine-containing gas component is measured. Method. 2. A packed layer containing an alkali metal or alkaline earth metal hydroxide, oxide, carbonate, bicarbonate or soda lime, or a packed layer containing an element which reacts with fluorine to form a compound. Consists of a packed bed and two packed layers containing alkali metal or alkaline earth metal hydroxides, oxides, carbonates, bicarbonates or soda limes, and a gas chromatography detector. An apparatus for measuring the concentration of fluorine-containing gas components, which comprises: 3. A packed layer containing an alkali metal or alkaline earth metal hydroxide, oxide, carbonate, bicarbonate or soda lime, or a packed layer containing an element which reacts with fluorine to form a compound. Consists of a packed bed and two packed layers containing alkali metal or alkaline earth metal hydroxides, oxides, carbonates, bicarbonates or soda limes, and a gas chromatography detector. An apparatus for measuring the concentration of fluorine-containing gas components in an excimer gas laser, characterized by: 4. A method for measuring the concentration of a component in a sample gas containing fluorine or the like, wherein the gas is an alkali metal or alkaline earth metal hydroxide, oxide, carbonate, bicarbonate or soda lime. A method for measuring the concentration of a fluorine-containing gas component, which comprises passing the gas through a packed bed containing the gas and then introducing the gas chromatography into a detector to measure the concentration of the gas component. 5. A packed layer containing a hydroxide, oxide, carbonate, bicarbonate or soda lime of an alkali metal or an alkaline earth metal, and a detector comprising gas chromatography. Fluorine-containing gas component concentration measuring device. 6. A packed layer containing a hydroxide, oxide, carbonate, bicarbonate or soda lime of an alkali metal or alkaline earth metal, and a detector comprising gas chromatography. Equipment for measuring the concentration of fluorine-containing gas components in excimer gas lasers.