Method for disposal of chlorosilane-based compounds

Abstract

The present invention provides a method for disposal of chlorosilane-based compounds, the method comprising the steps of: introducing a feed stream containing a chlorosilane-based compound into a liquid phase region containing a first aqueous solution within a column and reacting the chlorosilane-based compound with water to obtain an overhead discharge flow of the liquid phase region containing hydrogen chloride gas; introducing the overhead discharge flow of the liquid phase region into a packing region located above the liquid phase region; supplying a second aqueous solution containing a basic substance to a distribution region located above the packing region, and introducing into the packing region the second aqueous solution supplied to the distribution region; and neutralizing the hydrogen chloride gas included in the overhead discharge stream of the liquid phase region with the basic substance contained in the second aqueous solution in the packing region to obtain a bottom discharge flow of the packing region containing a chloride salt and a top discharge stream from the column.

Description

Method for treating chlorosilane compounds

[0001] Cross-citation with related applications

[0002] This application claims the benefit of priority from Korean Patent Application No. 10-2023-0189542, filed December 22, 2023, the entire contents of which are incorporated herein by reference.

[0003] Technology field

[0004] The present invention relates to a method for treating a chlorosilane-based compound, and more particularly, to a method for treating a chlorosilane-based compound by introducing a feed stream containing a chlorosilane-based compound into a liquid region containing a first aqueous solution, and bringing the upper discharge stream of the liquid region into countercurrent contact with a second aqueous solution.

[0005] In general, styrene-butadiene copolymers are used as synthetic rubbers, and compared to natural rubber, they have superior wear resistance and heat resistance, stable scorch resistance, and easy processability, so they can be used in various fields. During the manufacturing process of such styrene-butadiene copolymers, a chlorosilane coupling agent can be added to improve the physical properties of the product. When a stream containing a gaseous chlorosilane compound discharged from a storage tank storing the chlorosilane coupling agent is normally incinerated, harmful gases such as dioxins may be generated due to chlorine. Therefore, in order to safely process the chlorosilane compound, a stream containing the gaseous chlorosilane compound is introduced into a water phase region of a column where water exists, and hydrogen chloride generated by reacting the chlorosilane compound with water is dissolved in water. Through this, it was intended to reduce the discharge of hydrogen chloride, which is inevitably generated when processing the above chlorosilane compound, to the top of the column.

[0006] However, with current environmental regulations strengthening and lowering standards for hydrogen chloride emission concentrations, further reductions in hydrogen chloride emissions are essential to meet these standards. In other words, technologies are needed to prevent the inevitable release of hazardous substances that are generated when processing chlorosilane compounds in an environmentally friendly manner.

[0007] The problem to be solved by the present invention is to provide an effect of reducing the emission of chlorine, a harmful substance, while being able to process chlorosilane compounds in an environmentally friendly manner in order to solve the problem mentioned in the background technology of the above invention.

[0008] According to one embodiment of the present invention for solving the above problem, the present invention provides a method for treating a chlorosilane-based compound, comprising the steps of: introducing a feed stream containing a chlorosilane-based compound into a liquid phase region containing a first aqueous solution in a column and reacting the chlorosilane-based compound with water to obtain an upper discharge flow of the liquid phase region containing hydrogen chloride gas; introducing the upper discharge flow of the liquid phase region into a packing region located above the liquid phase region; supplying a second aqueous solution containing a basic substance to a distribution region located above the packing region and introducing the second aqueous solution supplied to the distribution region into the packing region; and neutralizing the hydrogen chloride gas contained in the upper discharge flow of the liquid phase region and the basic substance contained in the second aqueous solution in the packing region to obtain a lower discharge flow of the packing region containing a chloride salt and an upper discharge stream of the column.

[0009] According to the method for treating a chlorosilane-based compound of the present invention, the chlorine contained in the chlorosilane-based compound can be primarily converted into hydrogen chloride by first reacting the gaseous chlorosilane-based compound contained in the feed stream with water. A portion of the hydrogen chloride thus converted can be treated as wastewater as a hydrochloric acid solution dissolved in water. Meanwhile, if the hydrogen chloride that is not dissolved in water among the converted hydrogen chloride is discharged as hydrogen chloride gas, it may cause an air environmental problem. Therefore, the hydrogen chloride gas can be treated as wastewater in the form of a chloride salt by additionally neutralizing the hydrogen chloride gas with a basic compound. This enables environmentally friendly chlorine treatment compared to cases where the chlorosilane-based compound is discharged into the atmosphere without separate treatment or where the chlorosilane-based compound is treated by incineration.

[0010] Furthermore, since the method for treating the chlorosilane compound according to the present invention employs a water-based aqueous treatment system, it has the advantage of being inexpensive in cost associated with the treatment.

[0011] In addition, according to the method for treating the chlorosilane compound according to the present invention, when treating the chlorosilane compound based on water, i.e., when reacting the chlorosilane compound with water in an aqueous solution, the production of by-products, such as inorganic compounds or polymers, which are likely to be produced, can be prevented, thereby preventing disadvantages in the device / process caused by the by-products.

[0012] Figure 1 is a process diagram showing a method for treating a chlorosilane compound according to one embodiment of the present invention.

[0013] Figures 2 and 3 are process diagrams showing a method for treating a chlorosilane compound according to a comparative example of the present invention.

[0014] The terms or words used in the description and claims of the present invention should not be interpreted as limited to their usual or dictionary meanings, but should be interpreted as meanings and concepts that conform to the technical idea of ​​the present invention, based on the principle that the inventor can appropriately define the concept of the term to explain his or her own invention in the best way.

[0015] In the present invention, the term "stream" may refer to the discharge flow of a fluid within a process, and may also refer to the fluid itself flowing within a pipe. Specifically, the stream may refer to both the fluid itself flowing within the pipe connecting each device and the discharge flow of the fluid. Furthermore, the fluid may refer to a gas or a liquid, and cases where the fluid includes a solid component are not excluded.

[0016] Additionally, in the present invention, HCl is referred to as hydrogen chloride or hydrochloric acid regardless of the state in which it is dissolved in water, and unless otherwise specified, hydrogen chloride and hydrochloric acid refer to the same HCl.

[0017] Typically, waste generated during a process can be disposed of by burning the waste. However, this method can be problematic from an environmental perspective, as it generates hazardous substances such as dioxins, for example, when the waste is a compound containing chlorine. Therefore, there is a need for an environmentally friendly and desirable method for treating chlorine-containing compounds, rather than using combustion. In this regard, the present invention can treat chlorosilane compounds using water instead of the commonly used incineration method. The method for treating chlorosilane compounds is as follows.

[0018] Hereinafter, an apparatus for performing a method for treating a chlorosilane-based compound according to an embodiment of the present invention will be described with reference to FIG. 1. Specifically, the apparatus for implementing the method for treating a chlorosilane-based compound may include a column (100). The column (100) may include a liquid region (110), a packing region (120) positioned above the liquid region (110), and a distribution region (130) positioned above the packing region (120). The liquid region (110) may refer to a region in the column (100) filled with a first aqueous solution, and may be a region into which a feed stream (1) including a chlorosilane-based compound is introduced. The packing region (120) may refer to a region in the column (100) that includes packing as a filler, and may be positioned spaced apart from the liquid region (110). The above distribution area (130) may be an area into which a second aqueous solution containing a basic substance is introduced.

[0019] A method for treating a chlorosilane-based compound using such a column (100) is schematically as follows. The feed stream (1) is introduced into the liquid zone (110), and the chlorosilane-based compound and water may react to produce hydrogen chloride. Some of the hydrogen chloride produced in this way may be discharged to the bottom of the column (100) as a hydrochloric acid solution dissolved in water, and the hydrogen chloride not dissolved in water may rise as hydrogen chloride gas and flow into the distribution zone (120). Here, the bottom of the column (100) may be determined according to the direction in which the liquid descends within the column (100) based on the direction of gravity, and for example, the liquid supplied to the top of the column (100) may sequentially pass through the distribution zone (130), the packing zone (120), and the liquid zone (110) and then be discharged to the bottom of the column (100). Some of the hydrochloric acid aqueous solution discharged to the bottom of the column (100) may be mixed with a basic substance and supplied as a second aqueous solution to the distribution area (130). The second aqueous solution supplied to the distribution area (130) may flow into the packing area (120), where the basic substance and hydrogen chloride gas may undergo a neutralization reaction to produce a chloride salt. The chloride salt thus produced may move downward to the liquid phase area (110). Meanwhile, it may be environmentally desirable for the hydrogen chloride gas to not be discharged to the top of the column (100) via the distribution area (130) by undergoing a neutralization reaction with the basic substance in the packing area (120). Here, the upper part of the column (100) can be determined according to the direction in which the gas rises within the column (100) based on the direction of gravity, and for example, the gas supplied to the lower part of the column (100) can sequentially pass through the liquid region (110), the packing region (120), and the distribution region (130) and then be discharged to the upper part of the column (100).

[0020] More specifically, a method for treating a chlorosilane-based compound according to one embodiment of the present invention comprises the steps of: introducing a feed stream (1) containing a chlorosilane-based compound into a liquid phase region (110) containing a first aqueous solution in a column and reacting the chlorosilane-based compound with water to obtain an upper discharge flow of the liquid phase region (110) containing hydrogen chloride gas; introducing the upper discharge flow of the liquid phase region (110) into a packing region (120) located above the liquid phase region; supplying a second aqueous solution containing a basic substance into a distribution region (130) located above the packing region (120) and introducing the second aqueous solution supplied to the distribution region (130) into the packing region; And it may include a step of neutralizing the hydrogen chloride gas included in the upper discharge stream of the liquid region (110) in the packing region (120) and the basic substance included in the second aqueous solution to obtain a lower discharge stream of the packing region containing a chloride salt and an upper discharge stream of the column.

[0021] Specifically, a method for treating a chlorosilane-based compound according to one embodiment of the present invention may include a step of introducing a feed stream (1) containing a chlorosilane-based compound into a liquid phase region (110) containing a first aqueous solution in a column (100) and reacting the chlorosilane-based compound with water to obtain an upper discharge stream of the liquid phase region (110) containing hydrogen chloride gas.

[0022] Specifically, the feed stream (1) containing the chlorosilane-based compound may be a gaseous stream discharged from the upper portion of a storage tank (10) storing the chlorosilane-based compound. The chlorosilane-based compound may be, for example, a chlorosilane-based coupling agent used in a process for manufacturing a styrene-butadiene copolymer. More specifically, the storage tank (10) may be one or two or more, and when the storage tanks (10) are two or more, two or more types of chlorosilane-based compounds discharged from each storage tank may be processed simultaneously.

[0023] According to the present invention, the chlorosilane compound may include at least one of dichlorosilane (H2Cl2Si), trichlorosilane (HCl3Si), hexachlorodisilane (Cl6Si2), silicon tetrachloride (Tetrachlorosilane; SiCl4), and dimethyldichlorosilane (C2H6Cl2Si).

[0024] Meanwhile, as previously mentioned, when chlorosilane compounds containing chlorine are incinerated, harmful gases such as dioxin are generated. Therefore, when processing chlorosilane compounds containing chlorine, incineration of the compounds may be environmentally undesirable. In other words, there is a need to process the chlorosilane compounds through an environmentally friendly method other than incineration.

[0025] According to the present invention, the feed stream (1) containing the chlorosilane-based compound can be introduced into the liquid phase region (110) of the column (100) to cause the chlorosilane-based compound to react with water. At this time, the feed stream (1) can be introduced into the liquid phase region (110), for example, through a pipe connecting the upper portion of the storage tank (10) and the lower portion of the column (100). More specifically, the pipe for moving the feed stream (1) can be provided so as to protrude into the liquid phase region (110). When the feed stream (1) is introduced into the liquid phase region (110) through such a pipe, the gaseous chlorosilane-based compound can be more effectively dispersed in the liquid phase region (110).

[0026] According to the present invention, when the vertical length of the longitudinal cross-section of the liquid region (110) is 100%, the feed stream (1) can be introduced at a height of 20 to 80% downward from the liquid level of the liquid region (110) based on 0% of the liquid level of the liquid region (110). In this way, when the feed stream (1) is introduced at a height within the above range of the liquid region (110), the dispersion efficiency of the gaseous feed stream (1) within the liquid region (110) increases, so that the reaction that proceeds in the liquid region (110) can be promoted. Accordingly, the amount of the chlorosilane-based compound included in the feed stream (1) that does not react with water and rises from the liquid region (110) as an unreacted chlorosilane-based compound can be minimized.

[0027] Specifically, the feed stream (1) including the chlorosilane-based compound may further include nitrogen gas. The feed stream (1) may be a stream discharged to the upper portion of the storage tank (10), i.e., a stream obtained by mixing a storage tank upper discharge stream with a nitrogen stream (2) including nitrogen gas. Accordingly, the feed stream (1) may include nitrogen gas and a chlorosilane-based compound. As a specific example, the storage tank upper discharge stream may be moved through a storage tank upper pipe provided at the upper portion of the storage tank (10), and the nitrogen stream (2) may be moved through a nitrogen supply pipe connected to the storage tank upper pipe.

[0028] Specifically, by continuously introducing nitrogen gas in this manner, the pressure within the feed stream (1) can be maintained higher than the pressure within the liquid region (110) within the column (100). Through this, the first aqueous solution present in the liquid region (110) can be prevented from flowing back into the storage tank (10). In addition, the feed stream (1) can be continuously introduced into the liquid region (110) containing the first aqueous solution.

[0029] Meanwhile, when the chlorosilane compound included in the feed stream (1) is silicon tetrachloride and dimethyldichlorosilane, the chlorosilane compound and water can react in the liquid region (110) according to the following reaction formulas 1 and 2.

[0030] [Reaction Formula 1]

[0031] SiCl4+ 2H2O → SiO2+ 4HCl

[0032] [Reaction Formula 2]

[0033] (CH3)2-Si-Cl2+ 2H2O → HO-[(CH3)2-Si]-OH + 2HCl

[0034] Referring to the above reaction formulas 1 and 2, when a chlorosilane compound reacts with water, hydrogen chloride or hydrochloric acid (HCl) may be generated, which may be dissolved in water and included in the first aqueous solution, or hydrogen chloride that is not dissolved in water may rise in the form of a gaseous phase. In this way, since hydrogen chloride is easily dissociated in water when it comes into contact with water, even if hydrogen chloride is generated, it may be easy to dissolve it in water and treat it as wastewater.

[0035] Meanwhile, when the chlorosilane compound and water react, by-products other than hydrochloric acid may be generated. For example, when the chlorosilane compound is silicon tetrachloride, silicon dioxide (SiO2) may be generated, and when the chlorosilane compound is dimethyldichlorosilane, dimethyl silanediol (C2H8O2Si) may be generated. In this case, the silicon dioxide may be included in the first aqueous solution in a state in which it is precipitated in the first aqueous solution in a solid phase, and the dimethyl silanediol may be included in the first aqueous solution in a state in which it is dissolved in the first aqueous solution in a liquid phase.

[0036] Meanwhile, the lower discharge stream of the packing region (120) may be introduced into the liquid region (110). Here, the flow may refer to a fluid moving within the column (100). The lower discharge stream of the packing region (120) may include a basic substance that was not neutralized with hydrogen chloride in the packing region (120). Therefore, in the liquid region (110), hydrogen chloride and the basic substance may also be neutralized to produce a chloride salt. Through this, the amount of hydrogen chloride gas included in the upper discharge stream of the liquid region (110) may be reduced.

[0037] Meanwhile, the components and composition of the first aqueous solution included in the liquid phase region (110) may vary depending on the progress of the reaction performed in the liquid phase region (110), but may remain constant after the treatment process of the chlorosilane-based compound, which is performed as a continuous process, reaches a steady state. For example, the components and composition of the first aqueous solution may be affected by the feed stream (1) and the lower discharge flow of the packing region (120). Specifically, the first aqueous solution may be a solution containing water as a main component when the feed stream (1) is first introduced into the liquid phase region (110). However, as the treatment process of the chlorosilane-based compound is performed, the first aqueous solution may contain reactants included in the feed stream (1), liquid products resulting from the reaction performed in the liquid phase region (110), and components of the lower discharge flow of the packing region (120).

[0038] Meanwhile, the temperature of the liquid region (110) may be 20 to 50°C, and specifically 25 to 40°C. More specifically, when the temperature of the liquid region (110) is less than 20°C, the neutralization reaction between hydrogen chloride and the basic substance may proceed slowly in the liquid region (110), and thus the amount of hydrogen chloride gas included in the upper discharge stream of the liquid region (110) may increase. Meanwhile, when the temperature of the liquid region (110) exceeds 50°C, a side reaction may be promoted in the liquid region (110), and thus fouling may occur in the lower discharge stream of the column (100).

[0039] According to one embodiment of the present invention, the pH of the first aqueous solution included in the liquid region (110) can be maintained at 6 to 9. Such pH control can be controlled by adjusting the concentration of the basic substance included in the second aqueous solution supplied to the distribution region (130) by the flow rate of the basic stream (3) described below.

[0040] Specifically, when the pH of the first aqueous solution in the liquid region (110) is within the above range, the production of polymers due to side reactions that occur when reacting a chlorosilane-based compound with water in the liquid region (110) can be prevented. Through this, the possibility of fouling, that is, the phenomenon of pipes or devices being clogged by the polymer, can be minimized. Specifically, when the fouling does not occur, the cleaning cost incurred for cleaning the portion fouled by the polymer can be reduced, and the process can be operated for a long period of time without stopping the process, which may be preferable. For example, when the fouling occurs, when the chlorosilane-based compound is dimethyldichlorosilane, the dimethyl silanediol produced by the reaction of the dimethyldichlorosilane with water undergoes self-polymerization.

[0041] In addition, by maintaining the pH of the first aqueous solution at 6 to 9 in the liquid region (110), it is also expected that the effect of suppressing corrosion of the device and internal materials that may occur when the first aqueous solution is strongly acidic can be suppressed.

[0042] Meanwhile, the bottom discharge stream of the column and the upper discharge stream of the liquid region (110) may contain hydrogen chloride. Here, the hydrogen chloride may be a basic substance included in the bottom discharge stream of the packing region (120) and hydrogen chloride that has not undergone a neutralization reaction in the liquid region (110). Specifically, the bottom discharge stream of the column may contain hydrochloric acid dissolved in water, and the upper discharge stream of the liquid region (110) may contain hydrogen chloride gas that has not been dissolved in water.

[0043] According to one embodiment of the present invention, chlorine included in the upper discharge stream of the liquid phase region may be 10 ppm to 0.1 part by weight based on 1 part by weight of chlorine in the chlorosilane-based compound included in the feed stream. This may refer to the extent to which the chlorosilane-based compound or the chlorine compound derived therefrom does not react with water or an alkaline substance in the liquid phase region (110) and rises to a gas phase. Specifically, when the chlorosilane-based compound reacts with water in the liquid phase region (110), the residence time of chlorine in the liquid phase region (110) may increase during the process of conversion into hydrogen chloride, thereby securing time for the generated hydrogen chloride to dissolve in water or undergo a neutralization reaction with an alkaline substance. Through this, the amount of chlorine in the gas phase that does not react in the liquid phase region (110) and rises can be minimized.

[0044] Meanwhile, a pump (5) may be provided at the bottom of the column (100), and the pump (5) may serve to discharge a portion of the first aqueous solution to the bottom of the column (100) while maintaining a liquid region (110) filled with the first aqueous solution within the column (100). Therefore, a portion of the first aqueous solution discharged to the bottom of the column (100) through the pump (5) may be included in the bottom discharge stream of the column.

[0045] A method for treating a chlorosilane compound according to one embodiment of the present invention may include a step of introducing an upper discharge flow of the liquid region (110) into a packing region (120) located above the liquid region (110).

[0046] The upper discharge stream of the liquid region (110) may include a gaseous component rising from the liquid region (110). Specifically, the upper discharge stream of the liquid region (110) may further include, in addition to hydrogen chloride gas, nitrogen gas and unreacted chlorosilane-based compounds. Here, the nitrogen gas may be introduced into the column (100) through a nitrogen stream (2), and the unreacted chlorosilane-based compound may be a chlorosilane-based compound that has not reacted with water in the liquid region (110). This upper discharge stream of the liquid region (110) may rise and be introduced into the packing region (120).

[0047] According to the present invention, the packing area (120) may include random packing, and the random packing may include one or more of a Raschig ring, a Pall ring, a CMR ring, an IMTP ring, a Berl saddle, and a Metal Hypac. By including such random packing, the packing area (120) may increase heat transfer and / or mass transfer between gas and liquid supplied into the column (100).

[0048] The length of the packing region (120) may be 100 mm to 1000 mm, specifically, 100 mm to 1000 mm. Here, the length of the packing region (120) may refer to the vertical length of the longitudinal cross-section of the packing region (120). In this way, when the length of the packing region (120) is within the above range, the contact area between the gas and liquid flowing into the packing region (120) may increase. Specifically, the countercurrent contact between the upper discharge stream of the liquid region (110) and the second aqueous solution described below may be sufficiently performed in the packing region (120), so that the neutralization reaction between the hydrogen chloride gas contained in the upper discharge stream of the liquid region (110) and the basic substance contained in the second aqueous solution may be more activated. Accordingly, the amount of hydrogen chloride discharged to the top of the column (100) may be significantly reduced.

[0049] A method for treating a chlorosilane compound according to one embodiment of the present invention may include a step of supplying a second aqueous solution containing a basic substance to a distribution area (130) located above the packing area (120), and introducing the second aqueous solution supplied to the distribution area (130) into the packing area (120).

[0050] Specifically, the second aqueous solution may be derived from a mixed stream obtained by mixing a portion of the bottom discharge stream of the column with a basic stream (3) containing a basic substance. As described above, a portion of the first aqueous solution may be discharged through the bottom discharge stream of the column, and the bottom discharge stream of the column may be branched. Specifically, a portion of the bottom discharge stream of the column may be mixed with the basic stream (3) containing a basic substance and circulated to the column (100) as the second aqueous solution, and the remainder may be supplied to a wastewater treatment process for treatment as wastewater. Accordingly, the second aqueous solution may include components of the first aqueous solution, but the content of the basic substance included in the second aqueous solution may be higher than the content of the basic substance included in the first aqueous solution.

[0051] Specifically, the wastewater treatment process can treat byproducts contained in the bottom discharge stream of the column (100), such as solid silicon dioxide and liquid dimethyl silanediol. More specifically, the silicon dioxide can be treated as a solid waste, and the dimethyl silanediol can be decomposed through biological treatment.

[0052] Meanwhile, by mixing a portion of the bottom discharge stream of the column with the basic stream (3) and circulating it to the column (100), components that are not reacted in the liquid region (110) and / or the packing region (120) and are discharged as included in the bottom discharge stream of the column, such as basic substances, can be recycled to the column (100) and reacted.

[0053] That is, in order to treat chlorine, if a portion of the bottom discharge stream of the column is not circulated to the column (110) but fresh water or an alkaline aqueous solution is continuously supplied to the column (100), loss of reactants may occur, so a portion of the bottom discharge stream of the column containing water and alkaline substances may be circulated to the column (100) and reused as a reactant. Meanwhile, if the contamination level of the bottom discharge stream of the column is high, fresh water may be additionally supplied to the column (100).

[0054] The basic substance may include at least one selected from the group consisting of potassium hydroxide (KOH), barium hydroxide (Ba(OH)2), and sodium hydroxide (NaOH). When such a basic substance undergoes a neutralization reaction with hydrogen chloride, a chloride salt and water are generated, and the chloride salt can be dissociated into the water for treatment, which may be preferable in terms of chlorine treatment.

[0055] That is, the second aqueous solution can be supplied to the column (100), and specifically, can be supplied to the distribution area (130) within the column (100). The distribution area (130) can be equipped with a distributor so that the second aqueous solution can be sprayed toward the packing area (120). Through such a distributor, the second aqueous solution can be uniformly introduced into the packing area (120).

[0056] The content of the basic substance included in the basic stream (3) may be 1 to 5 wt%, specifically 1 to 3 wt%. The basic stream (3) may include a basic aqueous solution containing the basic substance. When the content of the basic substance included in the basic stream (3) is within the above range, when this basic stream (3) is mixed with a portion of the bottom discharge stream of the column and flows into the packing region (120) as a second aqueous solution, the neutralization reaction between the basic substance and hydrogen chloride may be promoted. Furthermore, the bottom discharge stream of the packing region (120) containing the product of the neutralization reaction of the basic substance and hydrogen chloride flows into the liquid region (110), whereby the pH of the first aqueous solution included in the liquid region (110) may be maintained at 6 to 9.

[0057] A method for treating a chlorosilane compound according to one embodiment of the present invention may include a step of neutralizing hydrogen chloride contained in the upper discharge stream of the liquid region (110) in the packing region (120) and a basic substance contained in the second aqueous solution, thereby obtaining a lower discharge stream of the packing region (120) containing a chloride salt and an upper discharge stream of the column.

[0058] Since the upper discharge flow of the liquid region (110) moves upward as a gas phase and the second aqueous solution moves downward as a liquid phase, the hydrogen chloride contained in the upper discharge flow of the liquid region (110) and the basic substance contained in the second aqueous solution can come into countercurrent contact in the packing region (120) and undergo a neutralization reaction.

[0059] According to one embodiment of the present invention, the neutralization reaction that proceeds in the packing area (120) can be performed according to the following reaction formula 3.

[0060] [Reaction Formula 3]

[0061] SiO2+ HCl + NaOH → SiO2+ NaCl + H2O

[0062] Referring to the above reaction formula 3, when sodium hydroxide, a basic substance, undergoes a neutralization reaction with hydrogen chloride, sodium chloride, a chloride salt, and water can be produced. Specifically, the sodium chloride can dissolve in water and descend into the liquid region (110).

[0063] Through this, since the hydrogen chloride gas that is not dissolved in water and rises in the liquid region (110) can be neutralized in the packing region (120), the amount of hydrogen chloride discharged to the top of the column (100) can be minimized. In particular, since the hydrogen chloride gas and the basic substance can be brought into contact more effectively in the packing region (120), the neutralization reaction between the hydrogen chloride gas and the basic substance can be promoted. In addition, by neutralizing the hydrogen chloride gas with the basic compound, the hydrogen chloride gas can be treated as wastewater in the form of a chloride salt. Through this, environmentally friendly chlorine treatment can be possible compared to the case of treating the chlorosilane compound by incineration.

[0064] Meanwhile, as described above, the upper discharge stream of the liquid region (110) may further include unreacted chlorosilane-based compounds in addition to hydrogen chloride gas. Since water is also present in the packing region (120) through the second aqueous solution, the unreacted chlorosilane-based compounds may react with water in the packing region (120). Through this, additional hydrogen chloride may be generated in the packing region (120), which may undergo a neutralization reaction with a basic substance.

[0065] That is, the hydrogen chloride gas rising from the liquid zone (110) and the hydrogen chloride or hydrochloric acid generated in the packing zone (120) can be neutralized with sodium hydroxide, which is a basic substance, in the packing zone (120). Through this, the amount of hydrogen chloride gas and unreacted chlorosilane-based compounds included in the upper discharge stream of the liquid zone (110) that are not reacted in the packing zone (120) and sequentially discharged to the upper portion of the column (100) through the packing zone (120) and the distribution zone (130) can be minimized. Therefore, it can be desirable from an environmental perspective because the concentration of chlorine included in the upper discharge stream of the column and discharged can be reduced.

[0066] Meanwhile, referring to FIG. 2, conventionally, a feed stream containing a chlorosilane-based compound was introduced into a liquid region containing water within a column, and the chlorosilane-based compound was reacted with water to produce hydrogen chloride, which was dissolved in water. Through this, an attempt was made to reduce chlorine emissions; however, simply reacting the chlorosilane-based compound with water made it difficult to control the amount of chlorine discharged from the top of the column to a level that satisfied environmental regulations.

[0067] In addition, for example, when the chlorosilane compound is dimethyldichlorosilane, there may be a problem that the dimethyl silanediol produced by the reaction of the dimethyldichlorosilane with water self-polymerizes. The self-polymerization of the dimethyl silanediol may be promoted, for example, under an acidic atmosphere or a basic atmosphere, or may be promoted even in a situation where there is insufficient moisture. Here, an acidic atmosphere may mean a case where the pH is less than 6, and a basic atmosphere may mean a case where the pH is greater than 9. In this case, water and polydimethylsiloxane are produced by the self-polymerization of the dimethyl silanediol, and fouling may occur in which the polydimethylsiloxane blocks pipes or devices. At this time, the self-polymerization of the dimethyl silanediol may proceed by a reaction as in the following reaction scheme 4.

[0068] [Reaction Formula 4]

[0069] nHO-[(CH3)2-Si]-OH → HO-[(CH3)2-Si-O]nH + (n-1)H2O

[0070] In this regard, according to the present invention, the chlorosilane-based compound can first be reacted with water in the liquid region (110) to convert chlorine contained in the chlorosilane-based compound into hydrogen chloride. A portion of the hydrogen chloride thus converted can be dissolved in water for wastewater treatment, and the remainder that is not dissolved in water can be further neutralized with a basic compound as hydrogen chloride gas. By neutralizing the hydrogen chloride gas with a basic compound in this way, the environmentally harmful hydrogen chloride gas can be treated as a chloride salt. Through this, when treating the chlorosilane-based compound, chlorine can be treated in an environmentally friendly way based on water, and the cost associated with the treatment is also low, which is advantageous. Furthermore, by additionally reacting the hydrogen chloride, that is, the hydrogen chloride gas, which is not dissolved in water compared to the past, with a basic substance to treat it in the form of a chloride salt, the emission of chlorine can be effectively prevented.

[0071] In addition, the present invention can prevent fouling by maintaining the pH of the first aqueous solution included in the liquid region (110) at 6 to 9 and controlling the temperature to 50°C or lower, thereby reducing side reactions that occur when a chlorosilane compound and water react, for example, self-polymerization of dimethyl silanediol that occurs when the chlorosilane compound is dimethyldichlorosilane.

[0072] Meanwhile, according to the present invention, through the neutralization reaction that takes place in the packing region (120), a lower discharge stream of the packing region (120) containing water and chloride and an upper discharge stream of the packing region (120) containing nitrogen gas can be obtained. Here, the nitrogen gas is introduced into the column (100) through the nitrogen stream (2), but may be nitrogen gas that is not reacted but rises sequentially through the liquid region (110) and the packing region (120).

[0073] The lower discharge stream of the packing region (120) may be moved downward as a liquid to the liquid region (110), and the upper discharge stream of the packing region (120) may be moved upward as a gas to the distribution region (130). Specifically, the upper discharge stream of the packing region (120) may be included in the upper discharge stream of the column and discharged to the atmosphere.

[0074] According to one embodiment of the present invention, the top discharge stream of the column may include 0 to 4 ppm of hydrogen chloride, 0.8 to 1 part by weight of nitrogen gas, and the remainder of gaseous components, based on 1 part by weight of the total top discharge stream of the column. Specifically, among the hydrogen chloride that has not been neutralized in the liquid zone (110) and the packing zone (120), gaseous hydrogen chloride may be included as hydrogen chloride gas in the top discharge stream of the column, but a lower content of hydrogen chloride included in the top discharge stream of the column may be preferable from an environmental perspective. Therefore, the present invention can minimize the content of hydrogen chloride included in the top discharge stream of the column by neutralizing the hydrogen chloride gas present in the column (100) with a basic substance through supply of a second aqueous solution including a basic substance.

[0075] Meanwhile, as described above, the lower discharge stream of the packing region (120) may further include a basic substance, for example, sodium hydroxide, that was not neutralized with hydrogen chloride in the packing region (120). Therefore, a neutralization reaction between hydrogen chloride and the basic substance may also proceed in the liquid region (110). However, even if hydrogen chloride is not neutralized with the basic substance in the liquid region (110) and is not dissolved in water and rises as hydrogen chloride gas, the amount of hydrogen chloride discharged to the upper portion of the column (100) may be reduced because an additional neutralization reaction proceeds in the packing region (120).

[0076] Hereinafter, the present invention will be described in more detail by way of examples. However, the following examples are intended to illustrate the present invention, and it will be apparent to those skilled in the art that various changes and modifications are possible within the scope and technical spirit of the present invention, and the scope of the present invention is not limited to these examples alone.

[0077] Example

[0078] Example 1

[0079] According to the process flow shown in Fig. 1, a treatment process of a chlorosilane compound was performed.

[0080] Specifically, a stream including silicon tetrachloride and dimethyldichlorosilane, which are chlorosilane compounds discharged to the upper portion of a storage tank (10), was mixed with a nitrogen stream (2) including nitrogen gas to obtain a feed stream (1), and the feed stream (1) was introduced into a liquid region (110) including a first aqueous solution in a column (100). At this time, the feed stream was introduced at a height of 50% downward from the liquid level of the liquid region (110). The pH of the first aqueous solution included in the liquid region (110) was 7.

[0081] In the liquid zone (110), silicon tetrachloride and dimethyldichlorosilane were reacted with water to produce hydrogen chloride, silicon dioxide, and dimethyl silanediol. Sodium hydroxide, which was introduced into the liquid zone (110) through the lower discharge stream of the packing zone (120) described below, neutralized with the hydrogen chloride to produce water and sodium chloride. Among the hydrogen chloride gaseous substances that were not neutralized with sodium hydroxide in the liquid zone (110), the gaseous substances were included in the upper discharge stream of the liquid zone (110) as hydrogen chloride gas. The upper discharge stream of the liquid zone (110) further included nitrogen gas and unreacted chlorosilane compounds (silicon tetrachloride and dimethyldichlorosilane). Based on 1 part by weight of chlorine in the chlorosilane compounds included in the feed stream, the chlorine included in the upper discharge stream of the liquid zone was 10 ppm.

[0082] Meanwhile, the bottom discharge stream of the column contained a portion of the first aqueous solution, specifically hydrogen chloride, sodium chloride, silicon dioxide, and dimethyl silanediol. The bottom discharge stream of the column was discharged by a pump (5) provided at the bottom of the column (100).

[0083] The upper discharge stream of the above liquid zone (110) was introduced into a packing zone (120) located above the above liquid zone (110). The length of the packing zone (120) was 300 mm. Meanwhile, the lower discharge stream of the column was branched, and a portion of the lower discharge stream of the column was mixed with a basic stream (3) containing sodium hydroxide and supplied as a second aqueous solution to a distribution zone (130), and the remainder was treated as wastewater. The content of sodium hydroxide, which is a basic substance, contained in the basic stream (3) was 1 wt%.

[0084] The second aqueous solution supplied to the distribution area (130) was introduced into the packing area (120), and the hydrogen chloride gas contained in the upper discharge stream of the liquid area (110) and the sodium hydroxide contained in the second aqueous solution were neutralized. In addition, the unreacted chlorosilane compound and water contained in the upper discharge stream of the liquid area (110) were reacted in the packing area (120) to generate hydrogen chloride. Through this, a lower discharge stream of the packing area (120) containing water and sodium chloride and an upper discharge stream of the packing area (120) containing nitrogen gas were obtained. At this time, the lower discharge stream of the packing area (120) further contained sodium hydroxide, hydrogen chloride, silicon dioxide, and dimethyl silanediol.

[0085] The upper discharge stream of the above packing area (120) was discharged through the distribution area (130) and then through the upper discharge stream of the column. The upper discharge stream of the column contained 0 ppm of hydrogen chloride, 0.99 parts by weight of nitrogen, and the remainder of gaseous components, based on 1 part by weight of the total upper discharge stream of the column. Meanwhile, the lower discharge stream of the above packing area (120) was introduced into the liquid phase area (110).

[0086] As a result, it was confirmed that the content of hydrogen chloride contained in the upper discharge stream of the column in Example 1 was 0 ppm, and that no chlorine was discharged to the upper portion of the column (100). In addition, since there was no fouling caused by polymers generated through side reactions during the reaction occurring within the column, long-term operation of the process was possible.

[0087] Example 2

[0088] In the above Example 2, a chlorosilane compound was treated using the same process flow as Example 1, except that the pH of the first aqueous solution included in the liquid region was maintained at 5.5.

[0089] As a result, the content of hydrogen chloride included in the upper discharge stream of the column was 2 ppm based on 1 part by weight of the total upper discharge stream of the column. In Example 2, the flow rate of the basic stream was reduced compared to Example 1 in order to control the pH of the first aqueous solution included in the liquid region to 5.5, so that the neutralization reaction between hydrogen chloride and the basic substance occurred slowly, and thus it was confirmed that the content of hydrogen chloride included in the upper discharge stream of the column increased compared to Example 1.

[0090] In addition, fouling occurred in the upper piping and pump of the storage tank, making long-term operation of the process impossible. This was because the acidic atmosphere of the liquid region promoted the self-polymerization of dimethyl silanediol, producing a large amount of polydimethylsiloxane.

[0091] Example 3

[0092] In the above Example 3, a chlorosilane compound was treated using the same process flow as Example 1, except that the pH of the first aqueous solution included in the liquid region (110) was maintained at 10.

[0093] As a result, the content of hydrogen chloride in the upper discharge stream of the column was 0 ppm based on 1 part by weight of the total upper discharge stream of the column, but fouling occurred in the upper pipe and pump of the storage tank, making long-term operation of the process impossible. This was because self-polymerization of dimethyl silanediol was promoted under the basic atmosphere of the liquid region, producing a large amount of polydimethylsiloxane.

[0094] Meanwhile, in the above Example 3, it was confirmed that the content of hydrogen chloride in the upper discharge stream of the column was lower than in Example 2. In response to this, in Example 3, the flow rate of the basic stream was increased compared to Example 2 in order to control the pH of the first aqueous solution included in the liquid region to 10, thereby promoting the reaction between the basic substance and hydrogen chloride. Accordingly, there was no hydrogen chloride discharged to the upper portion of the column (100).

[0095] Comparative example

[0096] Comparative Example 1

[0097] According to the process flow shown in Fig. 2, the treatment process of the chlorosilane compound was performed.

[0098] Specifically, a feed stream (1) containing silicon tetrachloride and dimethyldichlorosilane, which are chlorosilane compounds discharged to the upper part of the storage tank (10), was introduced into a liquid region (110) containing water in the column (100).

[0099] In the liquid region, silicon tetrachloride and dimethyldichlorosilane were reacted with water to produce hydrogen chloride. Some of the hydrogen chloride produced in this way was dissolved in water to form an aqueous hydrochloric acid solution and was included in the liquid region (110), and the remaining hydrogen chloride that was not dissolved in water was increased as hydrogen chloride gas. The pH of the aqueous hydrochloric acid solution included in the liquid region was 2 to 3. Through this, an upper discharge stream of the liquid region (110) containing the hydrogen chloride gas and a bottom discharge stream of the column containing a portion of the aqueous hydrochloric acid solution were obtained. The bottom discharge stream of the column further contained silicon dioxide and dimethyl silanediol, and the upper discharge stream of the liquid region (110) contained nitrogen gas and unreacted chlorosilane compounds (silicon tetrachloride and dimethyldichlorosilane).

[0100] A portion of the bottom discharge stream of the column was mixed with a water stream (4) containing water and supplied to the liquid zone (110), and the remainder was treated as wastewater. Meanwhile, the upper discharge stream of the liquid zone (110) was included in the upper discharge stream of the column and discharged to the atmosphere. The content of hydrogen chloride included in the upper discharge stream of the column was 5 to 10 ppm based on 1 part by weight of the total upper discharge stream of the column.

[0101] In the above Comparative Example 1, since nitrogen gas was not included in the feed stream compared to Example 1, moisture in the liquid region (110) flowed back toward the storage tank (10) in a gaseous state, and dimethyl silanediol was generated in the upper pipe of the storage tank (10). The dimethyl silanediol thus generated self-polymerized to generate polydimethylsiloxane when the backflow of moisture stopped and the moisture evaporated and moved back to the column (100), making long-term operation of the process impossible.

[0102] In addition, in Comparative Example 1, the second aqueous solution containing a basic substance was not supplied to the column (100) compared to Example 1, so that even if the process was operated, it was confirmed that the content of hydrogen chloride included in the upper discharge stream of the column was higher than in Example 1. This is because the hydrogen chloride produced by the reaction of the chlorosilane compound and water is not dissolved in the water included in the liquid region (110), but rises in a gaseous state and is discharged to the upper part of the column.

[0103] Comparative Example 2

[0104] According to the process flow shown in Fig. 3, the treatment process of the chlorosilane compound was performed.

[0105] In the above comparative example 2, a chlorosilane compound was treated without having a liquid region containing the first aqueous solution in the column compared to example 1.

[0106] Specifically, a feed stream (1) containing silicon tetrachloride and dimethyldichlorosilane, which are chlorosilane compounds discharged to the upper portion of the storage tank (10), was introduced to the lower portion of the column (100). More specifically, the feed stream (1) was introduced below the packing area (120), and the feed stream (1) rose and flowed into the packing area (120).

[0107] Meanwhile, a basic aqueous solution containing sodium hydroxide was supplied to a distribution area (130) located above the packing area (120), and the basic aqueous solution descended and flowed into the packing area (120).

[0108] In the above packing area (120), the feed stream (1) and the basic aqueous solution are brought into countercurrent contact, and silicon tetrachloride and dimethyldichlorosilane contained in the feed stream (1) react with water contained in the basic aqueous solution to produce hydrogen chloride, silicon dioxide, and dimethylsilanediol. The hydrogen chloride thus produced undergoes a neutralization reaction with sodium hydroxide contained in the basic aqueous solution to produce sodium chloride and water.

[0109] That is, the reaction that proceeded in the above packing area (120) was performed including the reaction of a chlorosilane compound with water and the neutralization reaction of hydrogen chloride and sodium chloride. Through this, an upper discharge stream of the packing area (120) containing hydrogen chloride and a lower discharge stream of the packing area (120) containing silicon dioxide, dimethyl silanediol, sodium chloride, and water were obtained.

[0110] The upper discharge stream of the above packing section (120) was included in the upper discharge stream of the column through the distribution section (130), and the lower discharge stream of the above packing section (120) was included in the lower discharge stream of the column. The content of hydrogen chloride included in the upper discharge stream of the column was 3 to 6 ppm based on 1 part by weight of the total upper discharge stream of the column. A portion of the lower discharge stream of the column was mixed with a basic stream (3) containing sodium hydroxide and supplied to the distribution section (130) as the basic aqueous solution, and the remainder was treated as wastewater.

[0111] As a result, it was confirmed that Comparative Example 2 had an increased content of hydrogen chloride in the upper discharge stream of the column compared to Example 1. Specifically, Comparative Example 2 is a case where the liquid zone containing the first aqueous solution is not provided compared to Example 1, and the residence time in the packing zone during the process in which the chlorosilane compound and water react and are converted into hydrogen chloride is reduced, and accordingly, the time for the generated hydrogen chloride to dissolve in water is also significantly reduced. In addition, when the chlorosilane compound passes through the liquid zone containing water, the generated gas (hydrogen chloride) can be evenly distributed through a natural convection phenomenon, but in the case of Comparative Example 2 where the liquid zone does not exist, an uneven distribution phenomenon of hydrogen chloride occurred, causing a problem in which the mass transfer efficiency between gas and liquid within the packing zone rapidly decreased.

[0112] [Explanation of symbols]

[0113] 1: Feed stream

[0114] 2: Nitrogen stream

[0115] 3: Basic stream

[0116] 4: Water stream

[0117] 5: Pump

[0118] 10: Storage tank

[0119] 100: Column

[0120] 110: Liquid area

[0121] 120: Charging area

[0122] 130: Distribution area

Claims

1. A step of introducing a feed stream containing a chlorosilane compound into a liquid phase region containing a first aqueous solution in a column and reacting the chlorosilane compound with water to obtain an upper discharge flow of the liquid phase region containing hydrogen chloride gas; A step of introducing the upper discharge flow of the above liquid region into a packing region located above the above liquid region; A step of supplying a second aqueous solution containing a basic substance to a distribution area located above the packing area, and introducing the second aqueous solution supplied to the distribution area into the packing area; and A method for treating a chlorosilane compound, comprising the step of neutralizing hydrogen chloride gas contained in the upper discharge stream of the liquid region in the above packing region and a basic substance contained in the second aqueous solution, thereby obtaining a lower discharge stream of the packing region containing a chloride salt and an upper discharge stream of the column.

2. In paragraph 1, A method for treating a chlorosilane-based compound, wherein the feed stream containing the above chlorosilane-based compound further contains nitrogen gas.

3. In paragraph 1, A method for treating a chlorosilane compound, wherein the pH of the first aqueous solution included in the liquid region is maintained at 6 to 9.

4. In paragraph 1, A portion of the first aqueous solution is discharged through the bottom discharge stream of the column, A method for treating a chlorosilane compound, wherein the second aqueous solution is derived from a mixed stream obtained by mixing a portion of the bottom discharge stream of the column and a basic stream containing a basic substance.

5. In paragraph 4, A method for treating a chlorosilane compound, wherein the content of a basic substance included in the above basic stream is 1 to 5 wt%.

6. In paragraph 1, A method for treating a chlorosilane compound, wherein the basic substance comprises at least one selected from the group consisting of potassium hydroxide (KOH), barium hydroxide (Ba(OH)2), and sodium hydroxide (NaOH).

7. In paragraph 1, A method for treating a chlorosilane compound, wherein the temperature of the liquid region is 20 to 50°C.

8. In paragraph 2, A method for treating a chlorosilane compound, wherein the top discharge stream of the column contains 0 to 4 ppm of hydrogen chloride, 0.8 to 1 part by weight of nitrogen gas, and the remainder of gaseous components, based on 1 part by weight of the total top discharge stream of the column.

9. In paragraph 1, A method for treating a chlorosilane-based compound, wherein the chlorosilane-based compound comprises at least one of dichlorosilane (H2Cl2Si), (trichlorosilane; HCl3Si), trichlorosilane (HCl3Si), hexachlorodisilane (Cl6Si2), tetrachlorosilane (SiCl4), and dimethyldichlorosilane (C2H6Cl2Si).

10. In paragraph 1, A method for treating a chlorosilane compound, wherein chlorine contained in the upper discharge stream of the above liquid region is 10 ppm to 0.1 part by weight based on 1 part by weight of chlorine in the chlorosilane compound contained in the feed stream.

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