JPH01187724A - Vacuum vessel - Google Patents

Abstract

PURPOSE:To facilitate reduction of hydrocarbon gas, especially methane in a vacuum vessel by arranging therein a catalytic substance including paradium by the use of alumina as a carrier. CONSTITUTION:A catalyst including paradium by the use of alumina as a carrier is arranged in a vacuum vessel so that hydrocarbon gas, especially methane in the vessel is adhered. It is found that a substance including paradium by the use of alumina as a carrier adheres hydrocarbon gas when vapor exists. It is therefore possible to reduce hydrocarbon gas, especially methane in the vacuum vessel.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention utilizes a catalyst containing palladium using alumina as a carrier, which is difficult to remove with ordinary exhaust means, and which requires harmful work when put into practical use with electron tubes, etc. The present invention relates to a vacuum container capable of continuously removing hydrocarbon gases, particularly methane, which may cause harmful effects.

[Prior Art] As is well known, the vacuum inside a vacuum container, such as an electron tube vacuum envelope, so-called valve, is usually evacuated by using a mechanical vacuum pump, oil diffusion pump, etc. to a fairly high degree of vacuum. After that, a getter is used to further increase the degree of vacuum. Since getters use chemically active metals to chemically adsorb gases, the types of gases adsorbed differ depending on the type of getter. For this reason, in the case of electron tubes, getters such as barium and magnesium getters, which have a good ability to adsorb oxygen, which reduces the electron emission ability of the cathode, have been used for a long time.

However, as has been pointed out for a long time, even after reaching a fairly high degree of vacuum, carbon-containing gas remains in the residual gas due to backflow of oil vapor from pumps that use oil or other causes. are doing.

On the other hand, there is a considerable amount of moisture in the atmosphere, especially in Japan's climate, and even if careful attention is paid to removal work and storage conditions,
Solid surfaces are often coated with a thin film of water. If this type of moisture adheres to the surface of a low-temperature object, it is possible to evacuate it to a point where the partial pressure of water vapor in the vacuum container is considerably low, but it may be adsorbed to the surface of the object, causing the generation of water vapor. Since the amount of water removed is not small (the surface area of the adsorbing object is relatively large), even if the exhaust operation is continued for a long time, it will evaporate one after another and will not be completely removed.

In addition, recent research has revealed that in tubes using barium getters, hydrocarbon gases, typically methane gas, are generated by the barium film and residual carbon-containing gas and water vapor. ing.

Hydrocarbon gases such as methane have a negative effect on the characteristics of the oxide cathode, which is the source of electron beams in cathode ray tubes such as television picture tubes and data display tubes, which are now widely used. In addition, various manufacturing operations (thin film formation, etc.) and measurement operations (surface analysis, etc.) using other vacuum containers often cause great harm to the operation of devices and equipment that operate in a vacuum. However, until now, there has been no exhaust means that effectively works on hydrocarbon gases.

[Problems to be Solved by the Invention] The present invention solves the conventional problem of hydrocarbon gases, typically methane gas, remaining in a vacuum container and causing various harmful effects, and It is an object of the present invention to provide a vacuum container equipped with an effective adsorption means for.

[Means for Solving the Problems] In order to solve the above problems, in the present invention, a catalyst containing alumina as a carrier and palladium is installed inside the container, so that the inside of the container can be heated in the presence of moisture. It adsorbs and reduces hydrocarbon gases, especially methane. In fact, as mentioned above, inside a normal vacuum container,
Since there is a large amount of water vapor source, there is no need to particularly introduce water vapor.

Note that objects containing palladium using alumina as a carrier have been commercialized as catalysts and are easily available.

[, Action] The present inventors have experimentally discovered that a material containing palladium using alumina as a carrier adsorbs hydrocarbon gas in the presence of water vapor, but the detailed mechanism is unclear. is still not clear.

As mentioned above, if no measures are taken, the concentration of hydrocarbon gases can rise to relatively high values, especially when barium getters are used; If you take , hydrocarbon gases will be continuously adsorbed.

The gas pressure is suppressed to a relatively low level, and there is no significant adverse effect as in the past, for example, due to the residual methane gas ions tr [in the area corresponding to the electron beam passing hole of the first grid electrode on the cathode surface of the cathode ray tube, This eliminates the possibility of holes being drilled into the nickel substrate, which is the carrier for the electron-emitting material.

[Example] Hereinafter, the present invention will be explained in more detail using Examples (experiments conducted by the inventor).

FIG. 1 shows an example used in experiments by the present inventor, and in the figure,
1 is a Beard-Alpert gauge (hereinafter abbreviated as B-A gauge), 2 is a leak valve that can adjust the flow rate, 3 is an orifice, 4 is a catalyst material containing palladium using alumina as a carrier, and 5 is this catalyst material Thermocouple capable of measuring temperature, 6 is B-A gauge, 7 is mass filter (quadrupole mass spectrometer: Q, M, S), 8 is leak valve, 9 is turbo molecular pump (T, M, P) , 10 are rotary pumps. Using the B-A gauge 1, leak valve 2, and orifice 3, methane can be kept flowing at a constant rate into a wide vacuum container.

Further, the ion current of various gases, that is, the amounts of those gases can be seen through the mass filter 7.

Figure 2 shows a state in which a catalyst material 4 containing palladium using alumina as a carrier and water are (preliminarily) present in the container shown in Figure 1, while methane is continuously introduced at a constant rate. This is a diagram showing what happens when the catalyst material 4 is heated to 400°C after a few minutes.The left side shows the ion current of methane and water measured by the mass filter 7, and the right side shows the total pressure (solid line). . From this figure, it can be seen that as the temperature of the catalyst material increases, the total pressure increases and the ion current of methane decreases even though the ion current of water also increases.

FIG. 3 shows a catalyst material 4 containing palladium using alumina as a carrier placed in the container shown in FIG. Heat to 200℃.

This is a diagram showing the situation when moisture was introduced after about 20 minutes, stopped, and then introduced again after about 40 minutes. In this figure, the total pressure is indicated by a broken line. From this figure, it can be seen that when no moisture is introduced, the catalyst substance does not act, and when moisture is introduced, the methane ion current value decreases.

FIG. 4 shows that the catalyst material 4 is placed in a container, - methane is continued to be introduced at a constant rate, and the catalyst material is heated.
This shows that methane does not decrease unless water is introduced.

From the experiments in the above examples, it is clear that the methane reduction effect is achieved by placing a catalyst material containing palladium using alumina as a carrier in a vacuum container and allowing methane and water to coexist. In the above embodiment, only the effect on methane was described, but it goes without saying that similar results can be obtained with respect to the reduction of other hydrocarbon gases.

[Effects of the Invention] As explained above, according to the present invention, by installing a catalyst material containing palladium using alumina as a carrier in a vacuum container, hydrocarbons that are difficult to reduce by other methods can be reduced. Gases, especially methane, can be reduced.

[Brief explanation of the drawing]

Figure 1 is a diagram showing an example used in experiments by the present inventor;
Figures 4 to 4 are diagrams showing experimental results according to Examples. 1... Beard Alper 1~ Gauge, 2... Leak valve adjustable to flow, 3... Orifice, 4...
... Catalyst material containing palladium using alumina as a carrier, 5... Thermocouple capable of measuring the temperature of the catalyst material, 6.
...[3-A gauge, 7...mass filter (quadrupole quality analyzer: Q, M, S), 8...leak valve, 9...turbo molecular pump Figure 1\10-self 1st section a・'horn' 4th figure saliva ze (minute)

Claims (1)

[Claims] 1. A vacuum container characterized by having a catalyst containing palladium using alumina as a carrier installed inside the container.