JP3260779B2 - Purification method of aromatic hydrocarbon vapor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for purifying an aromatic hydrocarbon vapor, and more particularly to a method for purifying an aromatic hydrocarbon vapor capable of removing oxygen contained as an impurity in an aromatic hydrocarbon vapor to an extremely low concentration. It relates to a purification method. Aromatic hydrocarbons such as benzene, toluene, and xylene have been used in large quantities mainly as raw materials for synthesis of chemical products and as solvents, but in recent years their uses have been diversified, and depending on the purpose, it is necessary to use one with extremely few impurities. Is done. For example, benzene is also used as a raw material for producing a diamond film, and high purity is required as the film forming technology advances.

[0002]

2. Description of the Related Art As a method for supplying benzene used in a process of forming a carbon material to a film, for example, benzene is put into a container such as a bottle having an open end, and the benzene is immersed in a thermostat to set an appropriate temperature. Benzene vapor generated by controlling the flow rate to a reactor for film formation while controlling the flow rate with a mass flow controller, or by generating benzene vapor by bubbling hydrogen, nitrogen, helium, etc. into a bubbler A method of supplying benzene vapor to the reactor is generally used. However, these vapors contain atmospheric components such as oxygen and moisture that are mixed in when the raw material liquid is charged into a bottle or bubbler, and are only purged by an inert gas or the like in the raw material liquid prior to use. Cannot be sufficiently removed. Among them, water can be removed by bringing aromatic hydrocarbon vapor into contact with a dehumidifier such as synthetic zeolite, but a method capable of removing oxygen to a low concentration is not known. .

[0003]

It is known to use a nickel-based catalyst as a method for efficiently removing oxygen contained in common gases such as nitrogen and hydrogen. Application to oxygen removal is conceivable. However, when a nickel-based catalyst is used, the aromatic hydrocarbon vapor is trapped by the catalyst in the initial stage of the vapor flow, and the concentration of the aromatic hydrocarbon decreases, and the hydrocarbon concentration in the outlet vapor is not stable. For this reason, when the flow rate of the steam is large, the concentration reaches a predetermined concentration in a relatively short time, but when the amount of the steam is small, such as 5 cm / sec or less at a linear velocity (LV), the supply to the process is started. However, there is a problem that it requires a long period of airflow. In addition, in the case of hydrogen-based aromatic hydrocarbon vapor, it was also found that the purity and concentration of the outlet vapor decreased because part of benzene and toluene was reduced by the catalytic action of nickel to produce by-products such as cyclohexane. As described above, when a nickel-based catalyst is used, an aromatic hydrocarbon vapor having a stable quality cannot be obtained, and it is difficult to efficiently form a film.
Therefore, there is a purification method capable of efficiently removing impurities in the aromatic hydrocarbon vapor, and at the same time, even at a low linear velocity, the vapor at the purification cylinder outlet can reach a predetermined flow rate and concentration in a short time after starting to flow the vapor. Requested.

[0004]

SUMMARY OF THE INVENTION The present inventors have developed a purification method for efficiently removing oxygen contained in aromatic hydrocarbon vapors such as benzene, toluene and xylene to an extremely low concentration and stabilizing the concentration in a short time. results of extensive studies to obtain, copper and these vapors were metal copper or reduction treatment
The present inventors have found that the oxygen concentration can be reduced to 0.1 ppm or less and further to 0.01 ppm or less by contacting with a purifying agent containing a compound as a main component, thereby completing the present invention.
That is, the present invention provides a method for converting an aromatic hydrocarbon vapor into metallic copper or
Is a method for purifying aromatic hydrocarbon vapor, which comprises contacting with a purifying agent mainly containing a reduced copper compound to remove oxygen contained as an impurity in the aromatic hydrocarbon vapor. The present invention relates to aromatic hydrocarbon vapors such as benzene, toluene and xylene alone, aromatic hydrocarbon vapors diluted with hydrogen (based on hydrogen gas) and inert gases such as nitrogen and argon (based on inert gas) (hereinafter collectively referred to as "aromatic hydrocarbon vapors"). (Hereinafter referred to as hydrocarbon vapor).

[0005] The purifying agent used in the present invention is mainly composed of copper compound obtained by reducing metallic copper or copper oxide. Further, a material containing a small amount of chromium, iron, cobalt, or the like as a metal component other than copper may be used. These purification agents may be used alone,
In addition, although it may be used in a form supported on a carrier or the like, it is usually used in a form supported on a carrier or the like for the purpose of increasing the contact efficiency between the surface of copper and steam. There are various methods for obtaining copper oxides.For example, adding an alkali such as caustic soda, caustic potash, sodium carbonate, and ammonia to copper nitrate, sulfate, chloride, organic acid salt, etc. to form an intermediate oxide. There are methods such as precipitating the body and calcining the obtained precipitate. These can be used as is, or alumina,
It is kneaded with a carrier substance such as silica, and usually formed into a molded product by extrusion molding, tablet molding, or the like, and is further crushed to an appropriate size, if necessary, before use. 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. In addition, since there are various catalysts such as commercially available copper oxide catalysts, those selected from them may be used. In short, any form may be used as long as reduced copper, copper oxide, and the like are finely dispersed and have a large surface area and a high contact efficiency with a gas. Generally, the larger the specific surface area of the purifying agent is, the better it is.
A range of about m ² / g is sufficient. Also,
The copper content is usually 1 to 95 wt%, preferably 20 to 95 wt% in terms of metallic copper. When the content of copper is less than 1 wt%, the deoxidizing ability is reduced. When the content of copper is more than 95 wt%, sintering occurs during reduction with hydrogen, and the activity may be reduced.

[0006] The refining agent is preferably subjected to an activation treatment prior to use in refining hydrocarbon vapor. Hydrogen reduction is usually used to activate the purifying agent . For example, 35
The reaction can be carried out by passing a mixed gas of hydrogen diluted with nitrogen or the like at 0 ° C. or lower through a purification column. However, since it is an exothermic reaction, care must be taken so that the temperature does not rise rapidly.

[0007] Purification of the hydrocarbon vapors are typically copper compound reduction treatment is carried out by passing the hydrocarbon vapor to the purification column filled, the hydrocarbon vapor by the hydrocarbon vapor is contacted with this Oxygen contained as an impurity is removed. The oxygen concentration in the hydrocarbon vapor applied to the present invention is usually 100 ppm or less. If the oxygen concentration is higher than this, the calorific value increases, so a heat removal means is required depending on the conditions. Purification filled in the purification column
Charging length of agent concentration of oxygen in the hydrocarbon vapors, but are determined by the characteristics and the oxygen removal conditions of use purification agent, usually a 50～1500Mm. If the filling length is shorter than 50 mm, the oxygen removal rate may decrease, and
If it is longer than 1500 mm, the pressure loss may be too large. The cylinder linear velocity (LV) of the hydrocarbon vapor at the time of refining differs depending on the oxygen concentration in the supplied hydrocarbon vapor and the operating conditions and cannot be specified unconditionally, but is usually 100 cm / sec or less, preferably 30 cm / sec or less. It is. The contact temperature between the hydrocarbon vapor and the refining agent is 200 ° C. or lower, preferably -10 to 100 ° C., as the temperature of the gas supplied to the inlet of the refining cylinder, and is usually room temperature (0 to 60 ° C.). No cooling is required. Atmospheric pressure is not particularly limited to the pressure, vacuum, although it is possible either process the pressure is, usually, 20 Kg ^/ cm 2 abs or less, preferably 0.1~10Kg ^/ cm 2 abs. Also, even if a small amount of water is contained in the hydrocarbon vapor, there is no particular adverse effect on the deoxygenation ability.Moreover, when a carrier is used, depending on the type, water is also removed at the same time. The oxygen removing step in the present invention can be further combined with a water removing step using a dehumidifier such as synthetic zeolite as needed, whereby the water is completely removed, and the purified hydrocarbon vapor of extremely high purity is removed. Can be obtained.

[0008]

EXAMPLES Example 1 (Preparation of Purifying Agent ) A 20 wt% aqueous solution of sodium carbonate was added to a 20 wt% aqueous solution of copper sulfate until the pH became 9 to 10 to precipitate crystals of basic copper carbonate. The crystals are repeatedly filtered and washed, dried at 130 ° C. for 5 hours in an air stream, and then dried at 300 ° C. for 5 hours.
Calcination was performed for a period of time to produce copper oxide. Alumina sol was added to the copper oxide (Cataloid-AS manufactured by Catalyst Chemical Industry Co., Ltd.).
-2) and kneaded with a kneader. Then in the air 1
It was dried at 30 ° C. for 5 hours, and further calcined at 350 ° C. for 5 hours, and the calcined product was crushed into granules. This was formed into a 6 mmφ × 4 mmH cylindrical pellet by tableting. This was crushed and sieved to collect 6 to 12 mesh. The specific surface area of this purifying agent was 39 m ² / g. A stainless steel purification cylinder having an inner diameter of 16.4 mm and a length of 400 mm was filled with 63.3 ml (101.3 g, packing density 1.6 g / ml, filling length 300 mm). (Activation treatment purification agent) temperature 180 ° C. at atmospheric pressure to 10 vol% of hydrogen (nitrogen base) in the purification tube, the flow rate 0.633L / min (LV = 5 cm
/ S) for 6 hours to perform a reduction treatment, and then cooled to room temperature. (Purification of benzene vapor) Subsequently, benzene vapor was purified. About 200 ml of liquid benzene was placed in a stainless steel bubbler having an inner diameter of 5.5 cm and a height of 20 cm.
The benzene vapor pressure was controlled by immersion in a constant temperature bath set as described above, and benzene was bubbled with nitrogen to generate a vapor containing 9 vol% benzene on a nitrogen basis. The oxygen concentration in the benzene-containing vapor was measured using a yellow phosphorus emission type oxygen analyzer (measurement lower limit concentration: 0.01 ppm), and was found to be 0.20 ppm. When this steam was passed through the purification cylinder at 0.633 L / min (LV = 5 cm / sec) and the oxygen concentration in the outlet steam was measured, no oxygen was detected and the concentration was 0.01 ppm or less. Further, even after 100 minutes from the start of the purification, the oxygen concentration of the outlet steam is 0.0
It was 1 ppm or less. Further, when the benzene concentration in the outlet vapor of the purification cylinder was measured by a gas chromatograph method, the same as in the inlet vapor 50 minutes after the start of the steam flow.
vol% was reached, and the measurement was continued for another 120 minutes, but there was no change. When the flow of the vapor containing benzene was stopped and sealed for 2 hours as it was, and the vapor was flowed again, the benzene concentration in the outlet vapor became the same as that in the inlet vapor in 16 minutes. Table 1 shows the results. Example 2 Example 1 was repeated except that the same kind of purifying agent as in Example 1 was used, and instead of nitrogen, hydrogen was used as the base gas and hydrogen-based steam containing 9 vol% benzene and 0.16 ppm of oxygen as impurities was used. Purification of benzene vapor was performed in the same manner. The benzene concentration reached 9 vol% as in the inlet steam 65 minutes after the start of the steam flow, and the measurement was continued for another 120 minutes, but there was no change. When the flow of the vapor containing benzene was stopped and sealed for 2 hours as it was, and the vapor was flowed again, the benzene concentration in the outlet vapor became the same as that in the inlet vapor in 16 minutes. Table 1 shows the results.

Example 3 ( Purifying agent ) Commercially available copper oxide catalyst (G10 manufactured by Nissan Gardler Co., Ltd.)
8) was used as a purification agent . This is Si
30 wt% as Cu using O ₂ and specific surface area of 120
m ² / g, a molded body having a diameter of 5 mm and a height of 4.5 mm. 63.3 ml of this copper oxide catalyst crushed to 8 to 10 mesh was 16.4 mm in inner diameter and 400 mm in length.
Was packed into a stainless steel purification cylinder having a filling length of 300 mm (filling density: 1.0 g / ml). (Reduction of refining agent) The purification tube to 10 vol% of hydrogen (nitrogen base) Temperature 180 ° C. at atmospheric pressure, the flow rate 0.633L / min (LV = 5 cm
/ S) for 6 hours to perform a reduction treatment, and then cooled to room temperature. (Purification of benzene vapor) Subsequently, benzene vapor was purified. 9 vol% generated by bubbling nitrogen gas in the same manner as in Example 1.
Benzene and nitrogen-based benzene vapor containing 0.20 ppm of oxygen as an impurity were passed through a purification column at 0.633 L / min (LV = 5 cm / sec), and the oxygen concentration in the outlet vapor was measured. Not detected, 0.01
ppm or less. Even after 100 minutes from the start of the purification, the oxygen concentration of the outlet steam was 0.01 ppm or less. Further, when the benzene concentration in the vapor at the outlet of the purifying cylinder was measured by gas chromatography, it reached the same concentration as that in the vapor at the inlet 50 minutes after the start of flowing the vapor, and furthermore 12
The measurement was continued for 0 minutes, but there was no change. Table 1 shows the results. Example 4 Example 3 was repeated except that the same type of purifying agent as in Example 3 was used, and instead of nitrogen, a hydrogen-based vapor containing 9 vol% of benzene as a base gas and 0.16 ppm of oxygen as an impurity was used instead of nitrogen. Purification of benzene vapor was performed in the same manner. In 60 minutes from the start of the steam flow, the volume reached 9 vol% as in the inlet steam, and the measurement was continued for another 120 minutes, but there was no change. Table 1 shows the results.

Example 5 The same kind of purifying agent as used in Example 1 was used for an inner diameter of 16.4 mm.
63.3 ml in a 400 mm long stainless steel purification cylinder
(101.3 g, packing density 1.6 g / ml, filling length 30
After the filling, an activation treatment was performed under the same conditions as in Example 1, and subsequently, purification of toluene vapor was performed. Nitrogen-based toluene vapor containing 3 vol% of toluene and 0.32 ppm of oxygen as an impurity generated by bubbling nitrogen gas into liquid toluene set at 21 ° C. was added at 0.633 L / min (LV = 5 cm /
(Sec), the oxygen concentration in the outlet steam was measured after flowing through the purification cylinder, and no oxygen was detected, and it was 0.01 ppm or less. Even after 100 minutes from the start of the purification, the oxygen concentration in the outlet steam was 0.01 ppm or less. Further, when the toluene concentration in the outlet of the purifying cylinder was measured by gas chromatography, it reached the same concentration as in the inlet steam 70 minutes after the start of the steam flow, and the measurement was continued for 120 minutes, but there was no change. Table 1 shows the results.

Comparative Example 1 A commercially available nickel catalyst (N-111, manufactured by JGC Corporation) was used. The composition is in the form of Ni + NiO, where Ni is 45
~ 47wt%, Cr2 ~ 3wt%, Cu2 ~ 3wt%,
The specific surface area is 161 m ² / g with diatomaceous earth 27 to 29 wt% and graphite 4 to 5 wt%, diameter 5 mm, height 4.5.
mm. 63.3 ml of this nickel-based catalyst crushed to 8 to 10 mesh was charged into the same purification cylinder as used in the examples, with a packing length of 300 mm (a packing density of 1.0 g / m2).
l). This was activated with hydrogen at normal pressure at a temperature of 150 ° C. and a flow rate of 0.465 l / min (LV = 3.6 cm / sec) for 3 hours, and then cooled to normal temperature. (Purification of benzene vapor) Subsequently, benzene vapor was purified. 9% by volume of benzene and 0.20 pp as impurities based on nitrogen generated as in Example 1.
0.633 l / min (Lv
= 5 cm / sec) and the oxygen concentration in the outlet steam was measured. As a result, no oxygen was detected and the concentration was 0.01 ppm or less. However, when the benzene concentration in the vapor at the outlet of the purifying cylinder was measured by gas chromatography, it was 5.9 vol% 60 minutes after the start of the vapor flow, and was 12%.
After lapse of 0 minutes, it was only 7.7 vol%. Table 1 shows the results. Comparative Example 2 A comparison was made except that a nickel-based catalyst similar to that of Comparative Example 1 was used, hydrogen was used as a base gas instead of nitrogen, and hydrogen-based benzene vapor containing 9 vol% benzene and 0.16 ppm oxygen as impurities was used. Purification was performed in the same manner as in Example 1, and the oxygen concentration in the outlet steam was measured. As a result, no oxygen was detected and the concentration was 0.01 ppm or less. However, when the benzene concentration in the gas at the outlet of the purifying cylinder was measured by gas chromatography, it was 1.8 vol% after 60 minutes from the start of flowing steam, and only 2.7 vol% after 120 minutes. However, it was confirmed that a large amount of 5.0% by volume of cyclohexane was formed as a by-product. Table 1 shows the results.

[0012]

[Table 1]

[0013]

According to the present invention, oxygen contained in aromatic hydrocarbon vapors such as benzene, toluene, xylene and the like, which has conventionally been difficult to remove, is reduced to an extremely low level of 0.1 ppm or less, more preferably 0.01 ppm or less. At the same time, by-products such as cyclohexane do not occur in the purification of hydrogen-based vapors, and ultra-high-purity aromatics of a specified concentration and flow rate can be obtained in a short time after starting the gas flow. It has become possible to obtain hydrocarbon vapors.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B01D 53/86 B01J 21/00-38/74 C07C 7/148

Claims (1)

(57) [Claims] 1. The method of claim 1, wherein the aromatic hydrocarbon vapor is converted to metallic copper or
A method for purifying aromatic hydrocarbon vapor, comprising contacting a purified agent mainly composed of a copper compound subjected to a primary treatment with oxygen to remove oxygen contained as an impurity in the aromatic hydrocarbon vapor.