JP5189342B2 - Gas processing method - Google Patents

Description

  The present invention relates to a method for removing impurities in a gas using a nickel-containing catalyst, and more specifically, a method for reducing a nickel-containing catalyst and using this to remove impurities contained in a raw material gas. About.

  In the semiconductor industry, hydrogen, ammonia, or inert gases such as nitrogen, helium, and argon are frequently used, but these gases are required to have extremely high purity. For this reason, conventionally, a catalyst made of a metal such as nickel is used to remove hydrogen, ammonia, or impurities such as oxygen, carbon monoxide and carbon dioxide contained in an inert gas to a very low concentration (purification) ) A method has been developed.

For example, a method in which crude hydrogen gas is brought into contact with a nickel catalyst subjected to a reduction treatment to remove carbon monoxide and carbon dioxide contained as impurities in the gas (Japanese Patent Laid-Open No. 8-508968, Japanese Patent Laid-Open No. 8-509454), A method in which crude ammonia is brought into contact with a reduced nickel catalyst to remove oxygen, carbon monoxide, and carbon dioxide contained as impurities in the gas (Japanese Patent Laid-Open Nos. 5-124813 and 6-107412), inert An example is a method in which a gas is brought into contact with a reduced nickel catalyst or copper catalyst to remove oxygen contained as an impurity in the gas (conventional technology disclosed in Japanese Patent Laid-Open No. 7-31877).
In addition, the nickel catalyst is used for removing impurities contained in various gases as described above, and is used as a catalyst for synthesizing various organic compounds, for example.

Japanese Patent Laid-Open No. 5-124813 Japanese Patent Laid-Open No. 6-107412 JP 7-31877 A Japanese National Patent Publication No. 8-508968 JP-T 8-509454

  The aforementioned nickel-containing catalyst is usually oxidized lightly after reduction of the nickel-containing compound so that the catalyst can be used immediately without taking the pre-treatment and the effect of the catalyst can be fully exhibited. It is manufactured and sold as a stabilized nickel catalyst that can be handled without ignition. However, even these stabilized nickel catalysts are still oxidizing materials (which are not necessarily flammable by themselves, but providing oxygen causes the combustion of normal objects or promotes the combustion of other objects. Because it is self-heating at high temperatures, it reacts with oxygen in the surrounding air that has become high temperature for some reason during transportation, etc., and generates heat. May cause fire or explosion.

Therefore, the problem to be solved by the present invention is to use one or more selected from oxygen, carbon monoxide, and carbon dioxide contained in a raw material gas such as hydrogen, ammonia, or an inert gas using a nickel-containing catalyst . In the gas treatment method for removing impurities, the risk of the nickel-containing catalyst generating intense heat is reduced, and the ability to remove impurities in the raw material gas by the nickel-containing catalyst (impurity removal amount per unit amount of catalyst) is reduced. It is to provide a way to maintain.

As a result of intensive studies to solve these problems, the present inventors brought one or more impurities selected from oxygen, carbon monoxide, and carbon dioxide into contact with a nickel-containing catalyst with a source gas containing impurities. In the gas processing method for removing from the gas, the high oxidation state nickel-containing catalyst is reduced and activated for use, thereby reducing the risk of intense heat generation and equivalent to the case where the oxidation treatment is not performed. As a result, the gas processing method of the present invention was reached.

That is, the present invention reduces the nickel-containing catalyst in an oxidized state in which 40 to 90% of the total nickel is nickel oxide in terms of the number of metal atoms, and reduces the nickel oxide to 20% or less of the total nickel in terms of the number of metal atoms. A gas treatment comprising: bringing the raw material gas into contact with the reduced nickel-containing catalyst to remove one or more impurities selected from oxygen, carbon monoxide, and carbon dioxide from the raw material gas. Is the method.
Further, the present invention oxidizes a nickel-containing catalyst in which 25 to 60% of the total nickel is nickel oxide in terms of the number of metal atoms so that 40 to 90% of the total nickel in the ratio of metal atoms is nickel oxide. The nickel-containing catalyst in the oxidized state is subjected to a reduction treatment so that the nickel oxide is 20% or less of the total nickel in the ratio of the number of metal atoms, and a raw material gas is brought into contact with the nickel-containing catalyst subjected to the reduction treatment , It is also a gas processing method characterized by removing one or more impurities selected from carbon monoxide and carbon dioxide from the source gas.

In the present invention, the ability to remove one or more impurities selected from oxygen, carbon monoxide, and carbon dioxide contained in a source gas such as hydrogen, ammonia, or an inert gas (impurity of impurities per unit amount of catalyst) The risk of the nickel-containing catalyst generating heat intensely can be reduced without reducing the removal amount.

The gas treatment method of the present invention uses a nickel-containing catalyst to remove one or more impurities selected from oxygen, carbon monoxide, and carbon dioxide contained in a source gas such as hydrogen, ammonia, or an inert gas. Applies to processing (purification) methods. Impurities contained in the source gas are usually 500 ppm or less. Impurities may include hydrogen (except when the gas to be treated is hydrogen), water, methane, etc., in addition to one or more impurities selected from oxygen, carbon monoxide, and carbon dioxide. The source gas may contain a plurality of impurities.

  In the gas treatment method of the present invention, the nickel-containing catalyst before being oxidized is mainly composed of metallic nickel or a nickel compound that is easily reduced, such as a hydroxide, carbonate, nitrate, or organic acid salt of nickel. However, the oxidation state is usually 25 to 60% of the total nickel, preferably 30 to 60%, more preferably in terms of the number of metal atoms (nickel atom number). Is 30-55%. Also, as a metal component other than nickel, a small amount of metal such as chromium, iron, cobalt, copper, etc. (preferably 50% or less, preferably 40% or less, more preferably 30% or less of the whole metal in terms of the number of metal atoms) It may be what is. These raw materials may be used alone or in combination. Further, for the purpose of increasing the contact efficiency between the nickel surface and the gas, it is preferably used in a form supported on a catalyst carrier or the like.

As a method for supporting nickel on a carrier, for example, carrier powder such as diatomaceous earth, alumina, silica alumina, aluminosilicate, or calcium silicate is dispersed in an aqueous solution of nickel salt, and further, alkali is added to the carrier powder. A cake obtained by precipitating the nickel component and then filtering and washing with water as necessary is dried at 80 to 150 ° C. and then baked at 300 ° C. or higher, and the baked product is pulverized, or NiCO ₃ , Ni (OH) ₂ , Inorganic salts such as Ni (NO ₃ ) ₂ and organic salts such as NiC ₂ O ₄ and Ni (CH ₃ COO) ₂ are fired and pulverized, and then heat-resistant cement is mixed and fired. It is done.

  These are usually formed into a molded body by extrusion molding, tableting molding or the like, and are used as they are or after being crushed to an appropriate size as required. As a molding method, a dry method or a wet method can be used, and in that case, a small amount of water, a lubricant or the like may be used. Moreover, since N-111 (Ni-diatomaceous earth) (made by JGC Corporation) etc. are marketed as a nickel-type catalyst, you may use what was selected from them. In short, metallic nickel, nickel compounds, etc. may be finely dispersed and have a large surface area and high contact efficiency with gas.

The above-mentioned nickel-containing catalyst has a BET specific surface area of usually 10 to 300 m ² / g, preferably 30 to 250 m ² / g. Moreover, the content rate of nickel with respect to the whole nickel containing catalyst is 5 to 95 wt% normally, Preferably it is 20 to 95 wt%. When the nickel content is less than 5 wt%, the impurity removal ability is lowered, and when it is higher than 95 wt%, there is a possibility that sintering occurs during reduction with hydrogen and the activity is lowered.

  The nickel-containing catalyst in the oxidation state according to the present invention requires that 40 to 90% of the total nickel in the ratio of the number of metal atoms is nickel oxide, preferably 45 to 85%, more preferably 50 to 80% nickel oxide. It is. The risk that a nickel-containing catalyst will generate heat strongly also depends on the nickel content of the catalyst, ie, a catalyst with a higher nickel content has a higher risk. Accordingly, if the catalyst has a higher nickel content, it is preferable that the nickel oxide content be in an oxidized state. However, in general, if the nickel oxide content is less than 40%, the nickel-containing catalyst may generate intense heat. However, if it exceeds 90%, the activity of the nickel-containing catalyst is not sufficiently recovered even if reduction treatment is performed.

  The nickel-containing catalyst in the oxidized state in the present invention can be used as it is even if it is a commercial product as long as the ratio of nickel oxide in the whole nickel is the above-mentioned ratio of the number of metal atoms. A nickel-containing catalyst is used in which an oxidation treatment is performed to increase the ratio of nickel oxide in the entire nickel. For example, the above-mentioned nickel-containing catalyst is filled in a processing vessel or a processing cylinder, and heated at 100 to 800 ° C., the empty tube linear velocity (LV) is 100 cm / sec or less, preferably 50 cm / sec or less for 0.5 to 25 hours. It can be prepared by contacting with a gas containing oxygen, preferably for 1 to 15 hours. The oxygen concentration in the oxygen-containing gas may be 20% or more from the start to the end of the oxidation treatment. However, in order to avoid a rapid oxidation reaction, a gas containing oxygen having a concentration of 5% or less is used immediately after the start of the oxidation treatment. It is preferable to gradually increase the oxygen concentration with the lapse of time and contact with a gas containing oxygen having a concentration of 20 to 40% immediately before the end. It is also possible to contact with a gas containing oxygen having a concentration exceeding 40% immediately before the end.

In the present invention, the above-mentioned nickel-containing catalyst in the oxidized state, even when heated, has no risk of reacting violently with oxygen in the surrounding air and generating heat. The vehicle can be transported to the destination by car, train, etc.), ship, aircraft and the like.
Further, the nickel-containing catalyst in the above-described oxidation state is activated by a reduction treatment before being used for an impurity removal treatment described later. The oxidation state of the nickel-containing catalyst subjected to the reduction treatment requires that the nickel oxide is 20% or less of the whole nickel in terms of the number of metal atoms, preferably 15% or less, more preferably 10% or less. The reduction treatment of the oxidized nickel-containing catalyst is usually performed by bringing the oxidized nickel-containing catalyst into contact with a gas containing hydrogen or an inert gas under heating at 100 to 800 ° C., preferably 150 to 400 ° C. The inert gas includes nitrogen, helium, argon and the like.

  The impurity removal treatment in the gas treatment method of the present invention is performed by circulating the raw material gas through a treatment cylinder filled with the nickel-containing catalyst subjected to the reduction treatment prepared as described above. The contact temperature between the source gas and the reduced nickel-containing catalyst is usually 0 to 100 ° C. Further, there is no particular limitation on the pressure at the time of contact between the raw material gas and the reduced nickel-containing catalyst, and the treatment can be performed at normal pressure, reduced pressure, or increased pressure. Performed under pressure. The gas cylinder linear velocity (LV) during the impurity removal process varies depending on the concentration of impurities in the supplied raw material gas and the operating conditions, and cannot be specified, but is usually 100 cm / sec or less, preferably 50 cm / sec. It is as follows.

  In the gas processing method of the present invention, the nickel-containing catalyst in the above-described oxidized state is filled in a processing cylinder, a reduction treatment is performed by circulating a hydrogen-containing gas or an inert gas therein, and further a raw material gas is distributed. Thus, it is preferable to remove impurities. More preferably, the nickel-containing catalyst before the oxidation treatment is filled in the treatment cylinder, and the oxidation treatment is performed by flowing an oxygen-containing gas therein, and then the hydrogen-containing gas or the inert gas is supplied. The reduction treatment is performed by circulation, and the impurities are removed by circulation of the raw material gas. By doing in this way, after an oxidation process or a reduction process, it can use as it is for the reduction process or the impurity removal process of source gas, without refilling a nickel containing catalyst. When the treatment cylinder is filled with a nickel-containing catalyst and the above-described series of treatments are performed, the filling length of the nickel-containing catalyst filled in the treatment cylinder is usually 10 to 2000 mm in practice. If the filling length is shorter than 10 mm, the impurity removal rate may be reduced during the gas impurity removal process, and if it is longer than 2000 mm, the pressure loss may be excessively increased.

In the gas treatment method of the present invention, a treatment cylinder filled with a reduced nickel-containing catalyst is used in combination with, for example, an adsorption cylinder filled with synthetic zeolite or a getter cylinder filled with a getter material. be able to. In the gas treatment method of the present invention, one or more impurities selected from oxygen, carbon monoxide, and carbon dioxide can be removed. For example, when the raw material gas further contains water, It is possible to remove all these impurities by using a combination with the adsorption cylinder.

  EXAMPLES Next, although an Example demonstrates this invention concretely, this invention is not limited by these.

[Example 1]
(Oxidation treatment of nickel-containing catalyst)
Commercially available nickel-containing catalyst (including metallic nickel and nickel oxide, Ni: 45-47 wt%, Cr: 2-3 wt%, Cu: 2-3 wt%, diatomaceous earth: 27-29 wt%, graphite: 4-5 wt%, ratio Surface area: 150 m ² / g, a molded body having a diameter of 5 mm and a height of 4.5 mm was used. This nickel-containing catalyst is a stabilized nickel-containing catalyst that is lightly oxidized after reduction and is ready for handling without being ignited in air. As a result of the analysis, 29% of the total nickel was nickel oxide in terms of the number of metal atoms. This nickel-containing catalyst, which was crushed to 8 to 10 mesh, was filled into a stainless steel treatment cylinder having an inner diameter of 54.9 mm and a length of 1000 mm so that the filling length was 500 mm.

  The heater of the processing cylinder is heated so that the temperature of the nickel-containing catalyst is 250 ° C., and a mixed gas of oxygen and nitrogen is gradually increased so that the concentration becomes 2% at the beginning and 30% at the end. The solution was circulated at a flow rate of 10 L / min, oxidized for 8 hours, and then cooled to room temperature. Next, as a result of taking out and analyzing a small amount of the nickel-containing catalyst from the processing cylinder, 41% of the total nickel was nickel oxide in terms of the number of metal atoms. Further, the following risk evaluation test was performed on the oxidized nickel-containing catalyst.

(Dangerous evaluation test of nickel-containing catalyst)
The risk assessment test for nickel-containing catalysts is a self-heating test (UN recommended test method “Manual of Test and Criteria-third revised edition
(ST / SG / AC.10 / 11 / rev.3) ”SECTION 33 RELATING TO CLASS 4.:Division 4.2 33.3.3 Substances
liable to spontaneous combustion, Test N.4: Test method for Self-heating
In accordance with the substances.), a stainless steel cubic sample container with a side of 10 cm is filled with a nickel-containing catalyst, suspended in a high-temperature bath at 140 ° C. (in an air atmosphere), and the temperature of the nickel-containing catalyst is continuously increased for 24 hours. This was done by measuring. Table 1 shows the results of the maximum temperature and the presence / absence of danger (having danger when exceeding 200 ° C). Table 1 shows the results of a similar risk evaluation test in which a nickel-containing catalyst was filled in a stainless steel cubic sample container having a side of 2.5 cm.

(Reduction treatment of nickel-containing catalyst)
For a treatment cylinder similar to the above filled with an oxidized nickel-containing catalyst, the heater of the treatment cylinder is heated so that the temperature of the nickel-containing catalyst is 250 ° C., and hydrogen is circulated at a flow rate of 2500 ml / min. And after performing the reduction process for 3 hours, it cooled to normal temperature. During this time, a part of the gas discharged from the processing cylinder was sampled, and the amount of water discharged was measured by a gas chromatograph, and the oxidation state of the reduced nickel-containing catalyst was calculated. As a result, it was found that about 10% of the total nickel in the nickel-containing catalyst subjected to the reduction treatment was nickel oxide in terms of the number of metal atoms.

(Impurity removal treatment test)
Next, nitrogen containing 30 ppm carbon dioxide as an impurity was circulated at a flow rate of 200 L / min under a pressure of 0.4 MPa at a temperature of 25 ° C. to perform a carbon dioxide removal treatment. During this time, a part of the gas discharged from the processing cylinder is sampled, the time until carbon dioxide starts to be detected is measured by a gas chromatograph, and the removal capability of the nickel-containing catalyst (the amount of carbon dioxide removed per 1 g of catalyst) is determined. Asked. The results are shown in Table 2. Further, the removal ability of hydrogen containing carbon dioxide as an impurity and ammonia containing carbon dioxide as an impurity were measured in the same manner. Further, nitrogen containing carbon monoxide as an impurity, hydrogen containing carbon monoxide as an impurity, ammonia containing carbon monoxide as an impurity, nitrogen containing oxygen as an impurity, hydrogen containing oxygen as an impurity, and ammonia containing oxygen as an impurity Similarly, the removal ability was measured. These results are shown in Table 2.

[Example 2]
(Oxidation treatment of nickel-containing catalyst)
In the oxidation treatment of the nickel-containing catalyst of Example 1, except that the oxidation treatment conditions were changed, a commercially available nickel-containing catalyst was used in the same manner as in Example 1, and 50% of the total nickel in terms of the number of metal atoms was nickel oxide. A nickel-containing catalyst was prepared.
(Dangerous evaluation test of nickel-containing catalyst)
In the same manner as in Example 1, the risk evaluation test of the oxidized nickel-containing catalyst was performed. The results are shown in Table 1.
(Impurity removal treatment test)
After the reduction treatment of the nickel-containing catalyst was conducted in the same manner as in Example 1, an impurity removal treatment test was conducted in the same manner as in Example 1. The results are shown in Table 2.

[Example 3]
(Oxidation treatment of nickel-containing catalyst)
In the oxidation treatment of the nickel-containing catalyst of Example 1, the commercially available nickel-containing catalyst was used in the same manner as in Example 1 except that the oxidation treatment conditions were changed. A nickel-containing catalyst was prepared.
(Dangerous evaluation test of nickel-containing catalyst)
In the same manner as in Example 1, the risk evaluation test of the oxidized nickel-containing catalyst was performed. The results are shown in Table 1.
(Impurity removal treatment test)
After the reduction treatment of the nickel-containing catalyst was conducted in the same manner as in Example 1, an impurity removal treatment test was conducted in the same manner as in Example 1. The results are shown in Table 2.

[Example 4]
(Oxidation treatment of nickel-containing catalyst)
In the oxidation treatment of the nickel-containing catalyst of Example 1, except that the oxidation treatment conditions were changed, a commercially available nickel-containing catalyst was used in the same manner as in Example 1, and 79% of the total nickel in terms of the number of metal atoms was nickel oxide. A nickel-containing catalyst was prepared.
(Dangerous evaluation test of nickel-containing catalyst)
In the same manner as in Example 1, the risk evaluation test of the oxidized nickel-containing catalyst was performed. The results are shown in Table 1.
(Impurity removal treatment test)
After the reduction treatment of the nickel-containing catalyst was conducted in the same manner as in Example 1, an impurity removal treatment test was conducted in the same manner as in Example 1. The results are shown in Table 2.

[Example 5]
(Oxidation treatment of nickel-containing catalyst)
In the oxidation treatment of the nickel-containing catalyst of Example 1, the commercially available nickel-containing catalyst was used in the same manner as in Example 1 except that the oxidation treatment conditions were changed. A nickel-containing catalyst was prepared.
(Dangerous evaluation test of nickel-containing catalyst)
In the same manner as in Example 1, the risk evaluation test of the oxidized nickel-containing catalyst was performed. The results are shown in Table 1.
(Impurity removal treatment test)
After the reduction treatment of the nickel-containing catalyst was conducted in the same manner as in Example 1, an impurity removal treatment test was conducted in the same manner as in Example 1. The results are shown in Table 2.

[Comparative Example 1]
(Dangerous evaluation test of nickel-containing catalyst)
A risk evaluation test of a commercially available nickel-containing catalyst was performed in the same manner as in Example 1. The results are shown in Table 1.
(Impurity removal treatment test)
After reducing the commercially available nickel-containing catalyst in the same manner as in Example 1, an impurity removal treatment test was conducted in the same manner as in Example 1. The results are shown in Table 1.

  As described above, the oxidized nickel-containing catalyst in the examples of the present invention has no reduction in the ability to remove impurities contained in the source gas and is safer in a high-temperature atmosphere than the nickel-containing catalyst of the comparative example. It became clear that the nature was high.

Claims (10)

The nickel-containing catalyst in an oxidized state in which 40 to 90% of the whole nickel is nickel oxide in the proportion of the number of metal atoms is reduced so that the nickel oxide becomes 20% or less of the whole nickel in the proportion of the number of metal atoms. A method for treating a gas, wherein a raw material gas is brought into contact with the prepared nickel-containing catalyst to remove one or more impurities selected from oxygen, carbon monoxide, and carbon dioxide from the raw material gas.   The gas treatment method according to claim 1, wherein the reduction treatment is performed after the oxidized nickel-containing catalyst is transported by at least one means selected from a vehicle, a ship, and an aircraft.   The oxidation-containing nickel-containing catalyst is filled in a processing cylinder, the reduction treatment is performed by flowing a hydrogen-containing gas or an inert gas therein, and the impurities are removed by further flowing a raw material gas. Item 2. A gas processing method according to Item 1.   The gas treatment method according to claim 1, wherein the nickel-containing catalyst in an oxidized state is obtained by oxidizing a nickel-containing catalyst in which nickel and / or a nickel compound is supported on a carrier.   The gas treatment method according to claim 4, wherein the carrier is diatomaceous earth, alumina, silica alumina, aluminosilicate, or calcium silicate. A nickel-containing catalyst having a nickel atom ratio of 25 to 60% of the total nickel in the ratio of metal atoms is oxidized so that 40 to 90% of the total nickel in the ratio of metal atoms becomes nickel oxide. The contained catalyst is reduced so that the nickel oxide is 20% or less of the total nickel in the ratio of the number of metal atoms, the raw material gas is brought into contact with the reduced nickel-containing catalyst , and oxygen, carbon monoxide, and dioxide A gas treatment method, wherein one or more impurities selected from carbon are removed from the source gas.   The nickel-containing catalyst is filled into a processing cylinder, the oxidation treatment is performed by flowing an oxygen-containing gas therein, the reduction treatment is performed by flowing a hydrogen-containing gas or an inert gas, and the raw material gas is further supplied. The gas processing method according to claim 6, wherein the impurities are removed by circulation.   The gas treatment method according to claim 6, wherein the nickel-containing catalyst is a catalyst in which nickel and / or a nickel compound is supported on a carrier.   The gas treatment method according to claim 8, wherein the carrier is diatomaceous earth, alumina, silica alumina, aluminosilicate, or calcium silicate.   The gas treatment method according to claim 6, wherein the oxidation treatment of the nickel-containing catalyst is performed by bringing the nickel-containing catalyst into contact with an oxygen-containing gas under heating, and increasing the oxygen concentration of the oxygen-containing gas over time.