JPH02141404A - Refining apparatus for gaseous hydrogen - Google Patents

Abstract

PURPOSE:To stably refine gaseous hydrogen in a high pure state by providing plural systems of the refining part in which the reaction cylinder converting oxygen impurities into water is connected in series with the adsorption cylinder adsorbing impurities in the gaseous hydrogen. CONSTITUTION:This refining apparatus of gaseous hydrogen is provided with >=2 systems of the refining parts A, B in which the refining cylinder 1 and the adsorption cylinder 2 are connected in series. In the reaction cylinder 1, the catalyst converting the oxygen impurities in the gaseous hydrogen into water is packed. In the adsorption cylinder 2, the impurities which are contained in the gaseous hydrogen and introduced from the reaction cylinder 1, such as water and cabon dioxide, are adsorbed and removed.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a hydrogen gas purification device, and more particularly, to a hydrogen gas purification device that purifies hydrogen gas by removing impurities such as oxygen, water, and carbon dioxide contained in hydrogen gas. The present invention relates to a hydrogen gas purification device for obtaining purified hydrogen gas of high purity.

Hydrogen gas is used in large quantities in semiconductor processes and the like, but with the recent rapid progress in the high degree of integration of semiconductors, extremely high purity hydrogen gas is required.

[Conventional technology]

A device for obtaining purified gas by removing small amounts of oxygen, moisture, carbon dioxide, etc. contained as impurities in hydrogen gas, including a reaction column and synthetic zeolite that converts oxygen into water using a catalyst such as Ni and Cu. There is a device that combines an adsorption cylinder for adsorbing and removing moisture, carbon dioxide, etc. with an adsorbent, and it is relatively widely used because hydrogen gas can be purified at room temperature. In this case, as the amount of adsorbed impurities increases, the adsorbent must be regenerated, so in order to continuously purify the gas, two adsorption cylinders are used, and these are used by switching alternately. Ru.

On the other hand, with regard to the reaction column, the catalyst is under a hydrogen gas atmosphere, and its activity is always maintained and regeneration treatment is not necessary, so only one reactor column is used in common for multiple adsorption columns.For example, a flow sheet as shown in Figure 2 is used. It is said to be a device for

In FIG. 2, the inlet and outlet of a reaction tube 11 filled with catalysts such as Ni and Cu are connected to a raw material gas supply path 14 and a reaction gas flow path, respectively. on the other hand,
The inlets of the adsorption cylinders 12 and 12 filled with an adsorbent such as synthetic zeolite and equipped with a heater H are connected to channels 13a and 13b, respectively, and the channels 13a and 13b are branched, and one of them is connected to the valves Vlla and 13b. Vll
b, respectively, and the other is a regeneration exhaust gas discharge path 1 via valves V12a and V12b.
5 is connected. Furthermore, the outlets of the adsorption cylinders 12 and 12 are connected to the channels 16a and 16b, and the outlets of the adsorption columns 12 and 12 are connected to the channels 16a and 16b.
and 16b are branched, one of which is the valve V13a and
The other side is connected to a purification gas extraction passage 17 via valves V14a and V14b, and to a regeneration purified self-gas supply passage 18 via valves V14a and V14b.

The raw hydrogen gas that has entered the reaction tube 11 from the supply path 14 comes into contact with the catalyst, so that the oxygen gas contained in the hydrogen gas reacts with the hydrogen gas and is converted to water, and after the contact, the hydrogen gas is reacted from the outlet. Out to the gas flow path. Adsorption purification of the gas discharged from the reaction column is carried out continuously by alternately using the adsorption columns 12 and 12. For example, when the left adsorption cylinder 12 is in the purification process, the valves Vlla and v1
3a is opened and the gas exits the reaction column 11, passes through the valve Vlla and the flow path 13a, enters the adsorption column 12 on the left side, and comes into contact with the adsorbent to adsorb and remove impurities such as moisture and carbon dioxide, resulting in purification. and is extracted through the flow path 16a, the valve V13a, and the extraction path 17. During this time, the adsorbent is regenerated in the adsorption cylinder 12 on the right side, but first, the purified self-gas for regeneration (
A portion of the purified hydrogen gas) enters the adsorption cylinder 12 on the right side from the supply path 18 through the valve V14b and the flow path 16b. Impurities such as moisture and carbon dioxide adsorbed on the adsorbent are desorbed by heating, and the adsorbent is regenerated. The impurities desorbed from the adsorbent flow into the flow path 13b together with the purified self-gas.
The regenerated exhaust gas is then discharged from the exhaust passage 15 through the valve V12b. While the adsorbent is regenerated in this manner, the conversion reaction continues in the reaction column 11 by constantly flowing the raw material gas regardless of the alternating switching between the adsorption columns 12 and 12.

[Problem to be solved by the invention]

As semiconductors become more highly integrated, submicron-level ultra-LSI
As the demand for improving the purity of purified gas increases in the manufacturing process of It has become clear that it cannot be obtained continuously and stably.

[Means to solve the problem]

The inventors of the present invention investigated the causes of these decreases in purity, and as a result of conducting intensive research to obtain a device that can constantly refine hydrogen gas in a highly pure state, the inventors discovered that a catalyst containing Ni or Cu was used at room temperature. Basically, oxygen reacts with hydrogen and is converted to water, but at the same time, impurity components such as oxygen and carbon oxides are fixed on the surface of the catalyst and the activity gradually decreases. It was discovered that the catalyst can be regenerated to its original activated state by heating in a hydrogen atmosphere, leading to the present invention.

That is, the present invention provides a reaction tube filled with a catalyst for converting oxygen gas contained as an impurity in hydrogen gas into water, and a reaction tube filled with a catalyst for converting oxygen gas contained as an impurity in hydrogen gas into water, and moisture and carbon dioxide contained in the hydrogen gas led from the reaction tube. A hydrogen gas purification device comprising an adsorption column for adsorbing and removing impurities such as This is a hydrogen gas purification device.

The present invention is used for high purity purification of hydrogen gas containing impurities such as oxygen, carbon oxide, carbon dioxide, and water.

The present invention will be illustrated and specifically explained with reference to the drawings.

Figure 1 is a flowchart of the hydrogen gas purification apparatus of the present invention. It is a sheet.

In Fig. 1, a reaction cylinder 1 filled with a catalyst such as Ni or Cu and an adsorption cylinder 2 filled with an adsorbent such as synthetic zeolite are connected in series, and a heater H is arranged in each cylinder. Two lines of purification sections A and B are provided. Reaction columns 1 and 1 of purification sections A and B are connected to channels 3a and 3b, and one of the channels 3a and 3b is branched, and one of them is connected to the source gas supply channel 4 through valves Via and Vlb. The other is valves V2a and V2
They are each connected to the regenerated exhaust gas discharge path 5 via b.

In addition, the adsorption cylinders 2 and 2 of purification sections A and B are connected to channels 6a and 6b, and the channels 6a and 6b are branched, and one of them is connected to the extraction channel 7 for purified gas via valves V3a and V3b. , the other one is connected to a regeneration self-gas (part of purified hydrogen gas) supply path 8 branched from the extraction path 7 via valves V4a and V4b.

[For production]

Purification of hydrogen gas is carried out continuously by alternately switching between two lines of purification sections A and B.

For example, when refining section A is in the refining process, valves Via and V
3a is opened, the raw hydrogen gas containing impurities such as oxygen, carbon oxide, and carbon dioxide enters the reaction column 1 of the refining section A from the supply path 4 via the valve Via and the flow path 3a, and enters the reaction column 1 of the refining section A. Most of the oxygen contained in the hydrogen gas reacts with the hydrogen and is converted to water, but at this time, a small amount of impurities such as oxygen and carbon monoxide are captured on the catalyst surface and are converted into gas. removed from inside. The gas then enters the adsorption column 2 and comes into contact with an adsorbent such as synthetic zeolite, where impurities such as carbon dioxide and water are adsorbed and removed, and the gas is purified to a high degree of purity. The purified gas coming out of the adsorption cylinder 1 is extracted through the flow path 6a, the valve V3a, and the purified gas extraction path 7.

If refining is continued for a long period of time in this state, impurities such as moisture and carbon dioxide adsorbed on the adsorbent will increase, and the adsorption capacity will not only decrease, but also oxygen, carbon oxides, etc. trapped on the surface of the catalyst will increase. impurities accumulate, making it impossible to remove carbon oxide, and the catalytic activity for converting oxygen to water also tends to gradually decrease. Therefore, before such an effect occurs, purification is switched to purification section B, and purification section A enters the catalyst and adsorbent regeneration step.

At the same time as opening valves Vlb and V3b, valves Via and V
By closing 3a, the raw hydrogen gas flows into the purification section B series and is purified. Next, by opening valves V2a and V4a while heating the catalyst and adsorbent in reaction column 1 and adsorption column 2 of purification section A with heaters H and H, a part of the purified hydrogen gas is used as regeneration gas and purified self-gas is supplied. From channel 8, it enters adsorption cylinder 2 of purification section A via valve V4a and flow channel 6a. Impurities such as carbon dioxide and water that were adsorbed on the adsorbent are desorbed by heating.
It enters the reaction tube 1 together with the regeneration gas, where the trace amount of oxygen captured by the catalyst reacts with hydrogen under heating and is converted to water, while at the same time trace impurities such as carbon monoxide are also released. The carbon oxide and carbon dioxide react with hydrogen by the Ni catalyst and are converted into methane, which is discharged together with the regeneration gas from the regeneration exhaust gas discharge path 5 via the flow path 3a and the valve V2a. This regenerates the adsorbent and activates the catalyst surface by high temperature hydrogen reduction in preparation for the next purification step.

By heating and regenerating the catalyst at the same time as the adsorbent, the activity is maintained, and hydrogen gas is always purified to a high degree of purity in a stable state.

In the present invention, the reaction column and the adsorption column which serve as the purification section do not necessarily have to be separate tubes, but may be combined into one tube filled with a catalyst and an adsorbent. Further, the purification section usually has two lines, but may have three or more lines if desired. Since the reaction column is regenerated at the same cycle as the adsorption column, its size is determined depending on the regeneration cycle time and other factors.

〔Effect of the invention〕

The hydrogen gas purification device of the present invention has at least two reaction columns, like the adsorption column, instead of only one in the past, so that the catalyst can be regenerated at the same time as the adsorbent is regenerated. It is possible to prevent a slight decrease in the purity of purified gas due to a decrease in catalyst activity during long-term use, which could not be detected, and at the same time, it can also reliably remove carbon monoxide, allowing it to be continuously supplied to semiconductor processes, etc. It has become possible to consistently refine hydrogen gas in a highly pure state. Moreover, since regeneration can be repeated, the reaction tube only needs to be small, making the device more compact as a whole and allowing it to be installed in a narrower space.

〔Example〕

A refining apparatus having the same configuration as shown in FIG.
Inner diameter 28. Filled with 190g of molecular sieve 5A.
Hydrogen gas was purified using a purification device having two lines of purification sections each consisting of four adsorption cylinders connected in series.

Oxygen, -carbon oxide, and carbon dioxide gas were each mixed with 10% of hydrogen gas as a raw material gas using a mass flow controller.
Pressure 5Kgf/c BoG while adding so that it becomes ppm.
, purification flow rate was 2.7Nn (/h), and continuous purification was performed with a switching cycle of each purification section every 8 hours, and the purity of the purified gas was analyzed.Oxygen was measured using a trace oxygen analyzer (Fuji Electric - For carbon oxide and carbon dioxide gas, the gas at the outlet of the separation column was brought into contact with a Ni catalyst at 600°C in the presence of hydrogen using an FID gas chromatograph, and - carbon oxide and carbon dioxide were converted to methane. Thereafter, it was introduced into an FID (Flame Ionization Detector) for analysis.The results are shown in Table 1.

Table 1 Table 2 shows the relationship between the total amount of carbon monoxide and carbon dioxide added to the raw material gas and the total amount of methane in the recycled exhaust gas in each cycle (8 hours).

Table 2 While purification is being carried out in the purification section of one series, in the purification section of the other series, a portion of the purified gas is used while heating the reaction column to 200°C and the adsorption column to 350°C, under normal pressure. After performing heating regeneration treatment for 3 hours at a flow rate of 7 ONI/h, the heater was turned off, and purified hydrogen gas was flowed for an additional 4.5 hours to cool and prepare for the next purification.

In order to confirm the desorption of carbon monoxide and carbon dioxide from the Ni-based catalyst and adsorbent during this regeneration process, the amount of methane emitted in the regenerated exhaust gas was analyzed for each 8-hour regeneration cycle.

As shown in Table 2 (almost the entire amount of carbon monoxide and carbon dioxide removed by the Ni catalyst and adsorbent is desorbed from the catalyst and adsorbent during regeneration and at the same time reacts with hydrogen to be converted to methane and discharged; It was found that the catalyst and adsorbent were regenerated reliably.

[Brief explanation of the drawing]

FIG. 1 is a flow sheet showing an example of the hydrogen gas purification apparatus of the present invention, and FIG. 2 is a flow sheet of a conventional hydrogen gas purification apparatus. The drawing numbers are as follows. 1 and 113 reaction cylinders 2 and 12. Adsorption cylinders A and B, purification section 3a, 3b; 6a, 6b, 13a, 13b
. 16aJ6b, flow path 4, 8, 14. and 18 supply lines 5 and 15. Discharge passages 7 and 17. Extraction path patent applicant Japan Bionics Co., Ltd. Agent Patent attorney
Sadafumi Kobori

Claims (1)

[Claims] A reaction tube filled with a catalyst for converting oxygen gas contained as an impurity in hydrogen gas into water, and adsorbing impurities such as moisture and carbon dioxide contained in the hydrogen gas led from the reaction tube. A hydrogen gas purification device comprising an adsorption column for removing hydrogen gas, characterized in that the hydrogen gas purification device comprises at least two lines of purification sections in which the reaction column and the adsorption column are connected in series. .