JP2001305056A - Measurement method for trace metal carbonyl compound - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a measurement method for a trace metal carbonyl compound. SOLUTION: In this measurement method for measuring a trace metal carbonyl compound in gas, the gas is adsorbed with a cold alcohol solution adsorbent 15 after dust is removed by means of a filter means 13, concentrated nitric acid is added into the adsorbent 15 for determining the volume, and measurement of the trace metal carbonyl compound in the emission gas is carried out by measuring a concentration of tetra carbonyl cobalt by atomic absorption spectrometry or plasma emission spectrochemical analysis.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring trace metal carbonyl compounds, and more particularly to a method for controlling the analysis of harmful substances discharged from a combustion device such as a boiler and evaluating the performance of pollution control equipment. The determination of trace metal carbonyl compounds.

[0002]

BACKGROUND ART In Japan in the 1950's, many boilers using fuel such as petroleum, coal, LNG, and heavy oil were constructed in order to secure electric power accompanying rapid growth. At present, the situation is similar in other developing countries, though behind Japan, and the problem of air pollution caused by exhaust gas discharged from combustion equipment such as boilers is now serious in the global environment.

[0003] For these reasons, organizations such as the WHO (World Health Organization) and ACGIH (American Association for Occupational Health) have increased the types of regulated substances as harmful substances and strictly regulated their emission concentrations year by year. Ultra-minimal measurement technology is also required. As harmful substances are generally known, for example SOx, NOx, CO, in addition to a number of harmful compounds such as CO ₂ (234 or more) may, as a general term of compounds consisting a metal and carbonyl (CO) within the There are metal carbonyl compounds.

[0004] It is said that when a fuel contains a metal, it is generated in a combustion or high temperature and high pressure environment.
For example, when cobalt (Co) or iron (Fe) is contained in the fuel, tetracarbonyl cobalt {[Co (C
O) ₄ ] ₂ } and iron pentacarbonyl {Fe (CO) ₅ }
Respectively. Also, a small amount is always contained in gas generated by gasification of coal using high-temperature and high-pressure conditions.

To explain the nature and toxicity of such metal carbonyl compounds, tetracarbonylcobalt is a catalyst originally used for the reaction of ethylene series hydrocarbons with carbon monoxide and hydrogen to produce nearly 4,000 tons per year. Have been. At low temperatures, pale yellow crystals with an unpleasant odor. The vapor is deep yellow. Melting point -26.2
° C, the boiling point is about 10 ° C. It is carcinogenic and its toxicity includes respiratory tract, irritation, myocardial disorders, thyroid disorders, etc. ACGIH
The TWA (time weighted average) of the allowable concentration at the (American Industrial Hygiene Experts Council) is 0.1 mg / m ³ as Co.

[0006] Iron pentacarbonyl has been used as a catalyst for the synthesis of hydroquinone. At room temperature, it is a yellow oily liquid with a melting point of -20 ° C and a boiling point of about 102.5 ° C. It is stable in the dark but emits CO when exposed to light to decompose. It is flammable and ignites easily in air. ACG
TWA at acceptable concentrations at the IH
(Time-weighted average) is 1 mg / m ³ as Fe.

However, there is no technique for measuring the concentration of tetracarbonylcobalt and pentacarbonyliron in the exhaust gas and working environment of harmful substances generated by air leakage or combustion from a device used as a catalyst as described above.

In the conventional measurement, dust or dust flying is collected by a dust sampler for convenience, and the amount of metal such as cobalt (Co) and iron (Fe) in the dust and dust is analyzed. This is a simple method of converting the value into the amount of the metal carbonyl compound.

However, this method has a problem in that it is not a measurement of a metal carbonyl compound itself which is a solid substance which is analyzed but is originally in a gaseous state. Therefore, development of a method for measuring the metal carbonyl compound itself is desired.

[0010] The present invention solves the above-mentioned problems in the prior art, and enables simple and rapid measurement of trace metal carbonyl compounds in combustion exhaust gas, which is applied to control analysis of harmful substances and performance evaluation of pollution control equipment. It is intended to provide a method for measuring a trace amount of a metal carbonyl compound which can be performed.

[0011]

Means for Solving the Problems To solve the above-mentioned problems, the invention of a method for measuring a trace metal carbonyl compound according to claim 1 is a method for measuring a trace metal carbonyl compound in a gas. It is characterized by absorbing with a cold alcohol solution, adding concentrated nitric acid to the absorption solution, measuring the volume, and measuring the concentration of tetracarbonylcobalt by atomic absorption analysis or plasma emission analysis.

[0012] The invention of claim 2 is a method for measuring a trace metal carbonyl compound in a gas, wherein the gas is dust-removed, then absorbed with a cold alcohol solution, and dilute nitric acid is added to the absorption solution to make a constant volume. The concentration of iron pentacarbonyl is measured by atomic absorption analysis or plasma emission analysis.

[0013] The invention of claim 3 is characterized in that, in claim 1 or 2, the condition for absorbing with a cold alcohol solution is carried out at -30 ° C or less.

[0014] The invention of claim 4 is characterized in that, in claim 1 or 2, water in the exhaust gas is removed before absorption with a cold alcohol solution.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described, but the present invention is not limited thereto.

FIG. 1 is a schematic diagram of an apparatus for collecting trace metal carbonyl compounds according to this embodiment of the present invention. FIG.
As shown in FIG. 1, the trapping device according to the present embodiment includes a filter means 13 for removing oxide-state metal and dust in flue gas 12 collected from a flue 10 via a collecting pipe 11.
And a moisture removing means 1 for removing moisture in the exhaust gas after removing metal, dust and the like in an oxide state by the filter means 13.
4 and an absorbing bottle 16 filled with an absorbing solution 15 for absorbing the metal carbonyl compound in the exhaust gas after removing water.

The filter means 13 is provided with a cylindrical filter paper 22 on the tip side of a glass dust filter 21 and protects the outside with a protective tube 23 made of aluminum.

The water removing means 14 comprises a drain bottle 25 immersed in a cooling bath 24, and the cooling bath 24 is cooled to about 0.degree.

In the present embodiment, a dehumidifying tower 26 is provided downstream of the drain bottle 25, and complete removal of moisture in exhaust gas is achieved.

The absorption bottle 17 can be a glass tube having a GI filter at the tip of the glass tube. This filter increases the gas contact area and improves the absorption rate.

From the absorption liquid 135, the trace metal carbonyl compounds in the exhaust gas, such as tetracarbonylcobalt and pentacarbonyliron, are collected.

A pump 31 for sucking gas and a gas meter 32 for measuring the amount of sucked gas are sequentially connected to the absorption bottle 16.

According to the present invention, it is possible to accurately measure the concentrations of tetracarbonylcobalt and pentacarbonyliron present in the exhaust gas containing various components such as fuel exhaust gas and having many measurement disturbance factors.

[1] Sampling of Sample First, a sampling pipe was inserted into the measurement point of the flue 10
Exhaust gas 12 is sucked. The sucked exhaust gas 12 is dust-removed by the filter means 13 and then the water removal means 14
And the moisture in the exhaust gas is removed by the dehumidification tower 26. Next, ethyl alcohol is used as the absorption liquid 15 of tetracarbonylcobalt and pentacarbonyliron, and the cooling temperature is adjusted to, for example, −50 ° C. by the cooling means 17, and dehumidified exhaust gas is allowed to pass therethrough. Collect carbonyl cobalt and iron pentacarbonyl at the same time.
After collection, the absorbent 15 is filtered with a filter and collected in a volumetric flask.

Further, after the absorption liquid is made to have a constant volume with cold ethyl alcohol, a predetermined amount of the liquid is divided into two parts. One of the fractions is used as an analysis sample for tetracarbonylcobalt, and the other is used as an analysis sample for iron pentacarbonyl. This analysis sample is called a test solution. Here, the use of ethyl alcohol as the absorbing solution in the absorption of the metal carbonyl compound is a substance in which both tetracarbonylcobalt and pentacarbonyliron are most easily absorbed,
This is because sample handling after collection is easy. Note that methyl alcohol may be used instead of ethyl alcohol.

The temperature for cooling by the cooling means 17 is such that the melting point of tetracarbonylcobalt is -26.2 ° C and the melting point of pentacarbonyliron is -20 ° C, so that it is collected at a temperature slightly lower than the melting point. There is a need. Therefore, at least the absorption condition needs to be absorbed in the vicinity of -30 ° C. When the exhaust gas to be analyzed is a high-temperature gas or the like, the cooling effect is deteriorated. Therefore, the cooling may be performed at about −50 ° C., more preferably at about −50 ° C. to about −114 ° C. In addition, -114 degreeC is a temperature at which ethyl alcohol solidifies.

[2] Analysis of Tetracarbonyl Cobalt In a state where the test solution is cooled to approximately zero to a known constant amount, concentrated nitric acid is added, and the volume is again adjusted to a constant volume with ethyl alcohol. By emission spectroscopy,
Analyze cobalt (Co). When the volume of the sample is fixed or the filtration operation is performed, it is preferable to use cold ethyl alcohol. This is because the boiling point of tetracarbonylcobalt is about 10 ° C., which is close to room temperature, so that vaporization is prevented when the liquid temperature reaches 10 ° C. in the course of the operation.

[3] Analysis of iron pentacarbonyl In a state where the test solution is cooled to a known constant amount to about zero degree, dilute nitric acid is added, and the volume is again adjusted to a constant volume with ethyl alcohol. By emission spectroscopy,
Analysis of iron (Fe) is performed.

<Example 1> [Measurement of tetracarbonylcobalt] Preparation for collection of tetracarbonylcobalt Using the apparatus shown in FIG. 1, the drain bottle 25 is cooled to 0 ° C. in the cooling tank 24, and a dehumidification tower 26 filled with calcium chloride is arranged. Until the absorption bottle 16 containing ethyl alcohol as the absorption liquid 15 is cooled.

2. Collection of Tetracarbonyl Cobalt (1) As a preparation before collection, the cooling means 17 is cooled to -50 ° C and the temperature is adjusted (about 2 hours). Then, absorption bottle 1
20 ml of the absorbing liquid 15 is put into the cooling tank 6 and cooled in the cooling tank 24. (2) Carefully insert the sampling tube 11 into the flue 10 and fix the tip at the measurement point. (3) The pump 31 is started, and the exhaust gas 12 is sucked and discharged through the gas meter 32. (4) Using the bypass pipe 15a of the absorption bottle 15, sufficiently evacuating the air, and replacing it with the exhaust gas 12 inside the pipe in which the gas flows. (5) Thereafter, the bypass line pipe 15a of the absorption bottle 16 is closed, the gas flow is switched to the absorption liquid 15 side, and a gas amount of 50 liter is sucked at a suction amount of 2 liter / min.

3. Preparation of sample solution (1) Transfer the absorption bottle 17 to a sample bottle (1000 ml, brown) cooled in a refrigerator or the like,
Wash with ethyl alcohol cooled to ℃, and also put the washing solution into a sample bottle (1000 ml, brown). At this time, care is taken that the total liquid volume does not exceed 50 ml. (2) The whole test solution in the sample bottle (1000 ml, brown) was filtered through a Teflon (registered trademark) filter (0.45 μm) using an absorption filter in a cool box, and the filtrate was cooled in a refrigerator or the like. Transfer to a 50 ml volumetric flask,
Similarly, add 1 ml of cooled concentrated nitric acid (HNO ₃ ) and shake gently. (3) Ethyl alcohol is added to the above volumetric flask to make a constant volume (50 ml), and this is used as a test solution. The ethyl alcohol used at this time may be at room temperature.

4. Analysis (1) The test solution was analyzed using a flameless atomic absorption spectrometer (wavelength: 24
01Å), the concentration of cobalt (Co) in the liquid is determined from the relationship between the absorbance and the concentration of the calibration curve prepared by the following operation. (2) Use the following procedure to create a calibration curve. a) Metallic cobalt (1.000 g) is nitric acid (1 + 1) 30 m
and heat diluted with pure water to a mark line with pure water in a 1000 ml volumetric flask to obtain a standard stock solution (1 mg / l). b) A standard stock solution (1 mg / l) was serially diluted with ethyl alcohol to obtain 10, 20, 30, 5, 5 as cobalt.
Adjust the standard solution to a concentration of 0,100 ppb. c) Transfer this standard solution to a flameless atomic absorption spectrometer (wavelength:
At 2401, the analysis is performed, and a calibration curve is created from the relationship between the absorbance and the concentration. The analyzer used for the analysis may be a plasma emission spectrometer in addition to the flameless atomic absorption spectrometer.

5. Calculation The tetracarbonyl cobalt concentration C (ppm) in the exhaust gas is calculated from the following equation (1). C = [A × 50 × 5.8027 × (22.4 ÷ 341.97)] / Vs (1) where: A: cobalt concentration (μg / ml) obtained from a calibration curve Vs: sample in a standard state Gas volume (l) 50: Test solution volume (50 ml) 341.97: Tetracarbonyl cobalt molecular weight 5.8027: Tetracarbonyl cobalt molecular weight (341.
97) ÷ Cobalt molecular weight (58.933) [Conversion coefficient for converting cobalt to tetracarbonylcobalt]

According to the present invention, tetracarbonyl of trace metal carbonyl compounds present in trace amounts in a gas which is conventionally unmeasurable, contains various components such as flue gas, and has many measurement interference factors is present. Cobalt can be measured directly and accurately.

According to the method of the present invention, 0.0005 ppm of tetracarbonylcobalt can be measured when 50 ml of combustion exhaust gas is absorbed and collected. Thereby, it is also possible to perform a normal measurement of the combustion exhaust gas and an accurate evaluation of the combustion device and the pollution prevention equipment.

<Example 2> [Measurement of iron pentacarbonyl] Preparation for collecting iron pentacarbonyl Using the apparatus shown in FIG. 1, the drain bottle 25 is cooled to 0 ° C. in the cooling tank 24, and a dehumidification tower 26 filled with calcium chloride is arranged. Until the absorption bottle 16 containing ethyl alcohol as the absorption liquid 15 is cooled.

2. Collection of iron pentacarbonyl (1) As a preparation before collection, the cooling means 17 is cooled to -50 ° C and the temperature is adjusted (about 2 hours). Then, absorption bottle 1
20 ml of the absorbing liquid 15 is put into the cooling tank 6 and cooled in the cooling tank 24. (2) Carefully insert the sampling tube 11 into the flue 10 and fix the tip at the measurement point. (3) The pump 31 is started, and the exhaust gas 12 is sucked and discharged through the gas meter 32. (4) Using the bypass pipe 15a of the absorption bottle 15, sufficiently evacuating the air, and replacing it with the exhaust gas 12 in the pipe 1 where the gas flows. (5) Thereafter, the bypass line pipe 15a of the absorption bottle 16 is closed, the gas flow is switched to the absorption liquid 15 side, and a gas amount of 50 liter is sucked at a suction amount of 2 liter / min.

3. Preparation of sample solution (1) Replace absorption bottle 17 with sample bottle (1000 ml, brown)
Then, the inside of the absorption bottle 17 is washed with ethyl alcohol, and the washing solution is also put into the sample bottle (1000 ml, brown). At this time, care is taken that the total liquid volume does not exceed 50 ml. (2) The entire test solution in the sample bottle (1000 ml, brown) was filtered through a Teflon filter (0.45 μm) using an absorption filter in a cool box, and the filtrate was cooled in a refrigerator or the like to obtain a 50-ml sample. Transfer to a flask, add 1 ml of similarly diluted diluted nitric acid (HNO ₃ ) and shake gently. (3) Ethyl alcohol is added to the above volumetric flask to make a constant volume (50 ml), and this is used as a test solution.

4. Analysis (1) The test solution was analyzed using a flameless atomic absorption spectrometer (wavelength: 24
At 83 °), the concentration of iron (Fe) in the liquid is determined from the relationship between the absorbance and the concentration of the calibration curve prepared by the following operation. (2) Use the following procedure to create a calibration curve. a) 1.0000 g of metallic iron is heated and decomposed with 10 ml of nitric acid (1 + 1), and diluted with pure water to the marked line in a 1000 ml volumetric flask to obtain a standard stock solution (1 mg / l). b) Standard stock solution (1 mg / l) was diluted stepwise with ethyl alcohol to obtain 10, 20, 30, 50, 10
Adjust the standard solution to a concentration of 0 ppb. c) Transfer this standard solution to a flameless atomic absorption spectrometer (wavelength:
At 2483 °), analysis is performed, and a calibration curve is created from the relationship between absorbance and concentration. The analyzer used for the analysis may be a plasma emission spectrometer in addition to the flameless atomic absorption spectrometer.

5. Calculation (1) From the following equation (1), the iron pentacarbonyl concentration C (ppm) in the exhaust gas is calculated. C = [A × 50 × 3.5080 × (22.4 ÷ 195.91)] / Vs (1) where A: cobalt concentration (μg / ml) obtained from the calibration curve Vs: sample in standard condition Gas amount (l) 50: Test solution volume (50 ml) 195.91: Pentacarbonyl iron molecular weight 3.5080: Pentacarbonyl iron molecular weight (195.91)
÷ Iron molecular weight (55.847) [Conversion coefficient for converting iron to iron pentacarbonyl]

According to the present invention, pentacarbonyl of trace metal carbonyl compounds present in trace amounts in a gas which is conventionally unmeasurable and contains various components such as flue gas and which has many measurement interference factors is present. It is possible to directly and accurately measure the concentration of iron.

According to the method of the present invention, 0.0005 ppm of iron pentacarbonyl can be measured when 50 ml of the combustion exhaust gas is absorbed and collected. Thereby, it is also possible to perform a normal measurement of the combustion exhaust gas and an accurate evaluation of the combustion device and the pollution prevention equipment.

[0043]

As described above, according to the invention of the method for measuring a trace metal carbonyl compound of claim 1 of the present invention, in the method for measuring a trace metal carbonyl compound in a gas, the gas is removed. After that, absorb with a cold alcohol solution, add concentrated nitric acid to the absorption solution, make the volume constant, and measure the concentration of tetracarbonylcobalt by atomic absorption analysis or plasma emission analysis. Can accurately and directly measure the concentration of tetracarbonyl cobalt among the trace metal carbonyl compounds.

According to a second aspect of the present invention, there is provided a method for measuring a trace amount of a metal carbonyl compound in a gas, wherein after removing the dust, the gas is absorbed with a cold alcohol solution, and dilute nitric acid is added to the absorption solution to make a constant volume. Quantitative measurement of iron pentacarbonyl concentration by atomic absorption analysis or plasma emission analysis. It is possible to directly and accurately measure the concentration of pentacarbonyl iron among trace metal carbonyl compounds present in trace amounts in gases having many interfering factors. it can.

According to the third aspect of the present invention, in the first or second aspect, since the condition for absorbing with a cold alcohol solution is carried out at -30 ° C. or less, the sample can be collected at the melting point of tetracarbonylcobalt and iron pentacarbonyl or lower. The accuracy is improved.

According to the invention of claim 4, according to claim 1 or 2, the water in the exhaust gas is removed before being absorbed by the cold alcohol solution, so that the clogging of the pipe due to the cooling of water during collection is prevented. You.

[Brief description of the drawings]

FIG. 1 is a schematic view of an apparatus for collecting trace metal carbonyl compounds according to an embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Flue 11 Sampling pipe 12 Exhaust gas 13 Filter means 14 Water removal means 15 Absorbing liquid 16 Absorption bottle 21 Dust filter 22 Cylindrical filter paper 23 Protective tube 24 Cooling tank 25 Drain bottle 26 Dehumidification tower 31 Pump 32 Gas meter

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G01N 1/22 G01N 1/22 K 1/28 1/28 K

Claims (4)

[Claims] 1. A method for measuring a trace amount of a metal carbonyl compound in a gas, comprising: removing a gas, absorbing the solution with a cold alcohol solution, adding concentrated nitric acid to the absorption solution, and measuring the volume by an atomic absorption analysis or plasma emission. A method for measuring a trace metal carbonyl compound, comprising measuring the concentration of tetracarbonylcobalt by analysis. 2. A method for measuring a trace amount of a metal carbonyl compound in a gas, the method comprising: removing dust from a gas; absorbing the solution with a cold alcohol solution; A method for measuring a trace metal carbonyl compound, wherein the concentration of iron pentacarbonyl is measured by analysis. 3. The method for measuring a trace metal carbonyl compound according to claim 1, wherein the condition for absorbing with a cold alcohol solution is -30 ° C. or less. 4. The method for measuring a trace metal carbonyl compound according to claim 1, wherein water in the exhaust gas is removed before absorption with a cold alcohol solution.