JPS5999351A - Assay of trace of oxygen in inert gas - Google Patents

Abstract

PURPOSE:To measure a trace of oxygen handily with a high sensitivity on line only with a simple heat reaction treatment by converting oxygen contained in an inorganic gas to methane to detect it through ionization thereof by a hydrogen flame. CONSTITUTION:Heaters 3 and 7 of first and second reaction furnaces 1 and 5 are energized to heat vessels 2 and 6 up to a higher temperature respectively while a stop valve 8 is opened to supply hydrogen gas to the second reaction furnace 6. At the end of such a preparation, a sample gas is injected through an injection hole 4. Oxygen in the sample gas entering the first reaction furnace 1 through a conduit reacts with carbon with platinum as catalyst to be converted into carbon monoxide, which is mixed with hydrogen from a cylinder 9 and enters the second reactor 5, where it reacts with hydrogen using nickel as catalyst to be changed to methane and water. Gas from the second reactor 5 is separated with a gas chromatograph 10 by components and sent into a hydrogen flame from a hole 12 for introducing gas to be inspected of a hydrogen flame ionization detector 11 to ionize. The amount of methane thus ionized corresponds to the amount of oxygen in the sample gas.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the ability to detect oxygen in inert gases with high sensitivity.

・Inorganic gas such as nitrogen and hydrogen and argon,
A thermal conductivity detector is used to detect oxygen contained in inert gases such as helium and neon (hereinafter referred to as inert gases), but its detection limit is about IOPPM, and high purity The control of inert gas was inadequate.

The present invention has been developed under these circumstances (in view of this, sensitivity power\it% <
, Ho9 aims to provide a simple oxygen analysis method.

That is, the present invention is characterized by converting oxygen in a non-hetapolytic gas into methane, and detecting this methane by ionizing it with a hydrogen flame.

The details of the present invention will be explained based on examples.

Figure 1 shows an example of the equipment used for undeveloped IJI, and the symbol l in the figure is the first reactor for converting # element into carbon monoxide. A heater 3 is provided around the outer periphery of a container JS 2 filled with equal amounts of grains and platinum catalyst, and one end of this furnace 1 is connected to a sample gas inlet 4, and the other end is connected to a second anti-single-core furnace 5, which will be described later. is connected to.

The second reactor (2) is a reactor for converting the carbon monoxide converted in the first reactor (1) into methane and water, and the outer periphery of a container (6) filled with two reactors. The reactor is configured as a furnace equipped with a heater 7 at one end, and one end is connected to a first reactor l and a hydrogen gas cylinder (9) etc. via a stop valve 8, and the other end is connected to a gas chroma I.・Connected to graph lO. Reference numeral 11 denotes a hydrogen flame ionization detector for detecting organic gas, and the sample residue to be injected into the inspection residue injection hole 12, that is, methane that has flowed in through the gas chromatograph IO, is heated in a hydrogen flame and ionized.

The detection circuit 15 is configured to measure these ions as a resistance change between the electrodes 13 and 14. In addition, the reference numeral 16 in the figure indicates a nitrogen gas cylinder for pressurizing the gas into the first reactor 1.

In the apparatus configured as described above, the heaters 3.7 of the first and second reactors 1 and 5 are energized to heat the container 2.6 to 950"O and 350°C, respectively, and then stopped. Open the valve 8 to supply hydrogen gas to the second reactor 6. When the sample gas is injected from the injection hole 4 after completing these preparations, it enters the first reactor 1 through the conduit. Oxygen in the sample gas is converted to carbon oxide by reacting with carbon using platinum as a catalyst at a temperature of 850°C.
2+c → CO), mixed with hydrogen from Pombe 9, enters the second reactor 5, where it reacts with hydrogen at a temperature of 350°C using nickel as a catalyst and converts into methane and water ( G O+ 3 H2→CH4+ H20), the gas coming out of the second reactor 5 is separated into components by a gas chromatograph 10 and sent to a hydrogen flame ionization detector 11.
The sample gas is sent into a hydrogen flame through the sample gas introduction hole 12 and ionized. The amount of methane ionized in this way is
-'It goes without saying that it corresponds to the amount of oxygen in the sample gas, so
The oxygen concentration can be determined by the detection circuit 15.

In the above embodiment, the sample gas was directly introduced into the first reactor, but if the sample gas contains organic gas, it is passed through a molecular sieve and then introduced into the first reactor. If the sample gas contains methane, cooling the molecular sieve with dry ice or ether will yield a sample residue from which methane has been removed.

〔Example〕

A 9'51 reactor was prepared by filling a quartz tube with an inner diameter of 8 mm and a length of 200 II 1 m with platinum and carbon for elemental analysis in one body, and a second reactor in which a nickel wire was housed in a quartz tube with an inner diameter of 8 mm and a Jk size of 1501 mm. Using a reactor of
We were able to detect oxygen present at a concentration of .

As explained above, according to the present invention, oxygen contained in an inorganic force is converted into methane, and this methane is ionized by a hydrogen flame and detected. Just by handling it, a minute amount of oxygen is released,
In addition, it can be determined online with high sensitivity.

[Brief explanation of drawings]

The drawing is a schematic yellow diagram showing an example of an apparatus used in the present invention. 1...First reactor 4...Sample injection hole 5...
...Second reactor 10...Gas chromatograph 1
1...Hydrogen flame ionization detector Applicant: Shimazu Co., Ltd. Manufacturing agent: 1.Physician: Kei Nishikawa, Katsuhiko Kimura

Claims (1)

[Claims] There is a carbon monoxide generation step in which sample waste is heated in the presence of carbon to convert oxygen in the sample gas into carbon monoxide, and the sample gas produced from this step is heated in the presence of hydrogen to convert the oxygen in the sample gas into carbon monoxide. A methane generation process in which carbon monoxide is converted to methane, and a hydrogen flame ionization detection process in which the sample gas emitted from the process is heated in a hydrogen flame to ionize and detect the methane. How to analyze oxygen.