Method for collecting organometallic compounds contained in gas

Abstract

To provide a method that enables simple and efficient collection and treatment of organometallic compounds contained in gas, without the need for special maintenance work, safety measures, or auxiliary equipment.SOLUTION: A method for collecting organometallic compounds in gas is provided, wherein a gas containing an organometallic compound is brought into contact with an acidic aqueous solution in a gas-liquid contact apparatus, thereby collecting the organometallic compound into the acidic aqueous solution.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a method for collecting organometallic compounds contained in a gas. [Background technology]

[0002] Organometallic compounds, such as alkylaluminum, are used as polymerization promoters for polyethylene, as raw materials for pharmaceutical intermediates, etc. Furthermore, in recent years, demand has also increased for semiconductor applications, and their usefulness as materials is increasing year by year.

[0003] Organometallic compounds are very difficult to handle because they generally ignite spontaneously when exposed to air and react violently with water or oxygen-containing compounds, presenting unique challenges to chemical plants that manufacture or use them.

[0004] Organometallic compounds are generally produced or used under inert gas, and therefore exhaust gas containing inert gas is generated due to the characteristics of the process. There are many problems caused by some of the organometallic compounds being entrained in the exhaust gas. Examples of such problems include the shutdown of combustion abatement equipment that treats the exhaust gas due to scaling of metal oxides, and the generation of white smoke (metal oxide components) from the exhaust gas outlet. These problems not only reduce the productivity of factories, but also affect the environmental hygiene around the factories, so there is a strong demand for the establishment of a technology for efficiently removing and collecting organometallic compounds contained in exhaust gas.

[0005] A method is known in which exhaust gas containing organometallic compounds is subjected to a primary oxidation treatment under heating to convert the compounds into metal oxides, which are then subjected to a secondary oxidation treatment (Patent Document 1).

[0006] Other methods include a method of capturing organometallic compounds with an organic solvent, etc. For example, a method of capturing organometallic compounds by introducing exhaust gas containing organometallic compounds below the surface of an amine compound liquid (Patent Document 2) and a method of capturing alkylaluminum with a liquid in which a long-chain fatty acid (oleic acid) is added to a hydrocarbon solvent (light oil) (Patent Document 3) are known. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2010-149082 A [Patent Document 2] JP 2013-235869 A [Patent Document 3] U.S. Pat. No. 4,826,665 Summary of the Invention [Problem to be solved by the invention]

[0008] As described above, in the method described in Patent Document 1, there is a risk that scaling of metal oxides occurs in the combustion furnace or piping, which may cause blockage of the ports or piping of the combustion furnace. In addition, the combustion process requires highly reactive fuels such as ethylene and hydrogen, and an open flame is used as a heat source for burning these fuels, so safety measures for the equipment are also required. Furthermore, depending on the amount of exhaust gas to be treated, an oxygen gas generator and a scrubber for cooling the treated gas may also be required. As described above, various types of equipment are required in conjunction with the combustion process, and the entire equipment tends to become complicated and large, making the combustion process disadvantageous in terms of cost.

[0009] The methods described in Patent Documents 2 and 3 are not practical from the viewpoint of handling and processing of waste liquid, since the organometallic compound remains dissolved in the organic solvent and accumulates. Furthermore, when the organometallic compound dissolves in the organic solvent, the viscosity of the liquid increases, which may cause foaming and a significant decrease in collection efficiency.

[0010] An object of the present invention is to provide a method for simply and efficiently collecting and treating organometallic compounds contained in a gas without requiring special maintenance work, security measures, incidental equipment, etc. [Means for solving the problem]

[0011] The inventors of the present invention have discovered that organometallic compounds can be efficiently collected by contacting a gas containing the organometallic compounds with an acidic aqueous solution, and have thus completed the present invention.

[0012] This application includes the following inventions. [Aspect 1] A method for collecting an organometallic compound contained in a gas, comprising contacting a gas containing the organometallic compound with an acidic aqueous solution in a gas-liquid contactor, and collecting the organometallic compound in the acidic aqueous solution. [Aspect 2] The method according to aspect 1, wherein the temperature of the acidic aqueous solution is 50°C to 100°C. [Aspect 3] The space velocity of the gas is 1,000 h -1 3. The method according to aspect 1 or 2, wherein: [Aspect 4] The method according to any one of aspects 1 to 3, wherein the concentration of the organometallic compound in the gas is 0.1 mg / L to 100 mg / L. [Aspect 5] The method according to any one of aspects 1 to 4, wherein the acidic aqueous solution contains at least one acid selected from the group consisting of hydrochloric acid, nitric acid, and sulfuric acid. [Aspect 6] The method according to any one of aspects 1 to 5, wherein the organometallic compound comprises at least one selected from the group consisting of trimethylaluminum, dimethylaluminum chloride, methylaluminum dichloride, methylaluminum sesquichloride, triethylaluminum, diethylaluminum chloride, ethylaluminum dichloride, ethylaluminum sesquichloride, triisobutylaluminum, dimethylzinc, and diethylzinc. [Aspect 7] The method according to any one of aspects 1 to 6, wherein the gas-liquid contactor is selected from the group consisting of a packed tower, a multi-tubular wetted-wall tower, a spray tower, a bubble tower, and a bubble cap tower. [Aspect 8] The method according to any one of the preceding aspects, wherein the gas and the acidic aqueous solution are contacted in a countercurrent, parallel current, or cross-flow manner. Effect of the Invention

[0013] According to the present invention, organometallic compounds contained in gas can be collected and treated simply and efficiently without requiring special maintenance work, security measures, or auxiliary equipment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] The present invention provides a method for capturing an organometallic compound contained in a gas. In one embodiment, the method for capturing an organometallic compound contained in a gas comprises contacting a gas containing the organometallic compound with an acidic aqueous solution in a gas-liquid contactor to capture the organometallic compound in the acidic aqueous solution.

[0015] In this embodiment, the metal oxide produced as a by-product of the reaction between the organometallic compound and the acidic aqueous solution is captured or dissolved in the acidic aqueous solution. This makes it possible to eliminate clogging of piping and the like due to scaling of the metal oxide, and to reduce the workload and man-hours of workers involved in maintenance work. In addition, since a general gas-liquid contactor can be used to capture the organometallic compound contained in the gas, the treatment facility can be made compact, and capital investment can be reduced. Furthermore, since no organic solvent is used, no safety measures are required for the facility, and running costs can be kept low.

[0016] The organometallic compound is not particularly limited, and examples thereof include organometallic compounds of Group 12 and Group 13. Since high collection efficiency can be obtained, the organometallic compound preferably contains at least one selected from the group consisting of alkylaluminum and alkylzinc, and more preferably contains at least one selected from the group consisting of trimethylaluminum, dimethylaluminum chloride, methylaluminum dichloride, methylaluminum sesquichloride, triethylaluminum, diethylaluminum chloride, ethylaluminum dichloride, ethylaluminum sesquichloride, triisobutylaluminum, dimethylzinc, and diethylzinc.

[0017] The gas containing the organometallic compound is not particularly limited, but is an inert gas such as nitrogen gas, helium gas, or argon gas. These inert gases are generally used in the production of organometallic compounds. The gas containing the organometallic compound may contain other gases such as air, oxygen gas, or carbon dioxide gas. The concentration of the inert gas in the gas containing the organometallic compound is preferably 80% by volume to 100% by volume, more preferably 90% by volume to 100% by volume.

[0018] The concentration of the organometallic compound in the gas containing the organometallic compound is not particularly limited, but is preferably relatively low in order to allow the reaction of the organometallic compound in the acidic aqueous solution to proceed gently. The concentration of the organometallic compound in the gas containing the organometallic compound is preferably 0.1 mg / L to 100 mg / L, more preferably 1 mg / L to 80 mg / L. By setting the concentration of the organometallic compound to 0.1 mg / L or more, the collection efficiency per volume of the acidic aqueous solution can be increased. By setting the concentration of the organometallic compound to 100 mg / L or less, the organometallic compound can be more stably collected in the acidic aqueous solution.

[0019] The acidic aqueous solution is not particularly limited, but is preferably an aqueous solution of an inorganic acid, and more preferably contains at least one acid selected from the group consisting of hydrochloric acid, nitric acid, and sulfuric acid.

[0020] The acid concentration of the acidic aqueous solution is not particularly limited, but is preferably 0.1% by mass to 20% by mass, more preferably 1% by mass to 10% by mass, and even more preferably 2% by mass to 8% by mass. By setting the acid concentration of the acidic aqueous solution to 0.1% by mass or more, the collection rate of organometallic compounds can be increased. By setting the acid concentration of the acidic aqueous solution to 20% by mass or less, collection of organometallic compounds can be carried out economically.

[0021] The pH of the acidic aqueous solution is preferably -1 to 4, more preferably -1 to 1. By adjusting the pH of the acidic aqueous solution to -1 or more, the organometallic compound can be economically collected. By adjusting the pH of the acidic aqueous solution to 4 or less, it is possible to prevent the organometallic compound or its reaction product with the acidic aqueous solution from precipitating from the acidic aqueous solution.

[0022] The temperature of the acidic aqueous solution is not particularly limited, but may be, for example, room temperature (20°C) to 100°C. The temperature of the acidic aqueous solution is preferably 50°C to 100°C, more preferably 60°C to 80°C. By setting the temperature of the acidic aqueous solution at 50°C or higher, the efficiency of capturing organometallic compounds can be further increased. By setting the temperature of the acidic aqueous solution at 100°C or lower, the energy cost for capturing can be reduced. Without being bound by any theory, it is considered that by increasing the temperature of the acidic aqueous solution, a poorly soluble salt (e.g., aluminum hydroxide) generated as a by-product upon contact reacts with the acid and is converted into a salt (e.g., aluminum chloride, aluminum nitrate, etc.) that is highly soluble in the acidic aqueous solution, or the generation of such a highly soluble salt is promoted.

[0023] The space velocity of the gas containing the organometallic compound is not particularly limited as long as the contact time between the gas and the acidic aqueous solution is sufficient to capture the organometallic compound. -1 Less than 500 hours, preferably -1 The space velocity of the gas containing the organometallic compound is preferably 10 h -1 More than 100 hours, preferably -1The space velocity of the gas containing the organometallic compound is preferably 10 h -1 ~1,000h -1 , more preferably 100h -1 ~500h -1 The space velocity of the gas containing the organometallic compound is 1000h -1 By setting the space velocity of the gas containing the organometallic compound at 10 h or less, the collection efficiency per volume of the acidic aqueous solution can be increased. -1 By satisfying the above, the treatment equipment for collection can be made compact, and capital investment can be reduced. The space velocity of the gas containing the organometallic compound is a value calculated by the following formula. Space velocity (h -1 ) = flow rate (m ) of gas containing organometallic compound fed into the gas-liquid contactor 3 / h) / space volume in gas-liquid contactor (m 3 )

[0024] The gas-liquid contactor is not particularly limited, but is preferably selected from the group consisting of a packed tower, a multi-tubular wetted-wall tower, a spray tower, a bubble tower, and a bubble cap tower.

[0025] The contact mode between the gas containing the organometallic compound and the acidic aqueous solution is not particularly limited, but it is preferable to contact the gas containing the organometallic compound and the acidic aqueous solution in a countercurrent, parallel flow, or crossflow manner.

[0026] The contact of the gas containing the organometallic compound with the acidic aqueous solution may be performed once (one pass), or the gas after contact may be returned to the same gas-liquid contactor for multiple contacts. The gas containing the organometallic compound may be contacted with the acidic aqueous solution through multiple gas-liquid contactors connected in series. In this embodiment, the concentrations of the acidic aqueous solutions in the multiple gas-liquid contactors may be the same or different. For example, the concentration of the acidic aqueous solution in the upstream gas-liquid contactor may be higher or lower than the concentration of the acidic aqueous solution in the downstream gas-liquid contactor.

[0027] All documents mentioned herein are incorporated by reference in their entirety.

[0028] The following examples of the present invention are for illustrative purposes only and do not limit the technical scope of the present invention. The technical scope of the present invention is limited only by the claims. The present invention can be modified, for example, by adding, deleting, and replacing the constituent elements of the present invention, without departing from the spirit of the present invention. EXAMPLES

[0029] The present invention will be described in more detail below with reference to examples, but these are not intended to limit the present invention in any way.

[0030] [Example 1] Nitrogen gas (gas flow rate: 3 L / h, TMAL concentration in gas: 50 mg / L) containing trimethylaluminum (TMAL) as an organometallic compound was introduced into a cylindrical glass bubbler (outer diameter 30 mm × height 300 mm) containing 5% by mass aqueous hydrochloric acid (80 g) at 70 °C for 2 hours to contact the aqueous hydrochloric acid. The residence time of the gas in the aqueous hydrochloric acid was 0.2 seconds, and the space velocity of the gas was 141 h -1 After contact with the gas, the amount of aluminum in the hydrochloric acid solution was calculated by back titration with EDTA. The amount of aluminum thus calculated was 285 mg, and the collection rate was 95%.

[0031] [Example 2] The contact was carried out under the same conditions as in Example 1, except that the temperature of the aqueous hydrochloric acid solution was set to 50° C. The amount of TMAL collected was 165 mg, and the collection rate was 55%.

[0032] [Example 3] The contact was carried out under the same conditions as in Example 1, except that the temperature of the aqueous hydrochloric acid solution was set to 20° C. The amount of TMAL collected was 60 mg, and the collection rate was 20%.

[0033] [Example 4] Except for using a 5% by mass aqueous solution of nitric acid at 70° C. instead of the aqueous solution of hydrochloric acid, the contact was carried out under the same conditions as in Example 1. The amount of TMAL collected was 290 mg, and the collection rate was 96%.

[0034] [Example 5] The contact was carried out under the same conditions as in Example 4, except that the temperature of the aqueous nitric acid solution was set to 50° C. The amount of TMAL collected was 156 mg, and the collection rate was 52%.

[0035] [Example 6] The contact was carried out under the same conditions as in Example 4, except that the temperature of the aqueous nitric acid solution was set to 20° C. The amount of TMAL collected was 75 mg, and the collection rate was 25%.

[0036] [Comparative Example 1] The contact was carried out under the same conditions as in Example 1, except that water at 20°C was used instead of the aqueous hydrochloric acid solution. The amount of TMAL collected was 30 mg, and the collection rate was 10%. It was found that the TMAL collection rate was higher in the acidic aqueous solution than in the neutral water.

[0037] [Comparative Example 2] The contact was carried out under the same conditions as in Example 1, except that a 5 mass% aqueous sodium hydroxide solution at 20°C was used instead of the aqueous hydrochloric acid solution. The amount of TMAL collected was 30 mg, and the collection rate was 10%. The reason that the collection rate was lower under alkaline conditions than under acidic conditions is thought to be that the reactivity of the by-produced aluminum hydroxide with sodium hydroxide is low.

[0038] [Comparative Example 3] The contact was carried out under the same conditions as in Example 1, except that kerosene at 20°C was used instead of the hydrochloric acid aqueous solution. The amount of TMAL collected was 295 mg, and the collection efficiency was 98%. When kerosene was used, the TMAL collection efficiency was extremely high, but it was found that when TMAL accumulated in the kerosene (TMAL concentration of 1 mass% or more), TMAL was stripped from the kerosene and entrained in the treated gas. Therefore, it was found that the collection of organometallic compounds with an organic solvent such as kerosene is not practical.

[0039] The results of Examples 1 to 6 and Comparative Examples 1 to 3 are shown in Table 1 below.

[0040] [Table 1]

[0041] Although the embodiments of the present invention have been described above, the present invention is not limited to these, and the devices, materials, various conditions, etc. used can be appropriately changed without departing from the spirit of the invention.

Claims

1. A method for collecting an organometallic compound contained in a gas, comprising contacting a gas containing the organometallic compound with an acidic aqueous solution in a gas-liquid contactor, and collecting the organometallic compound in the acidic aqueous solution.

2. The method according to claim 1, wherein the temperature of the acidic aqueous solution is from 50°C to 100°C.

3. The space velocity of the gas is 1,000 h －１ 3. The method according to claim 1 or 2, wherein:

4. 3. The method according to claim 1, wherein the concentration of the organometallic compound in the gas is from 0.1 mg / L to 100 mg / L.

5. The method according to claim 1 or 2, wherein the acidic aqueous solution contains at least one acid selected from the group consisting of hydrochloric acid, nitric acid, and sulfuric acid.

6. 3. The method according to claim 1, wherein the organometallic compound comprises at least one selected from the group consisting of trimethylaluminum, dimethylaluminum chloride, methylaluminum dichloride, methylaluminum sesquichloride, triethylaluminum, diethylaluminum chloride, ethylaluminum dichloride, ethylaluminum sesquichloride, triisobutylaluminum, dimethylzinc, and diethylzinc.

7. 3. The method according to claim 1 or 2, wherein the gas-liquid contactor is selected from the group consisting of a packed column, a multi-tubular wetted-wall column, a spray column, a bubble column, and a bubble cap column.

8. 3. The method according to claim 1 or 2, wherein the gas and the acidic aqueous solution are contacted in a countercurrent, cocurrent, or crossflow manner.

Images