Method and equipment for synthesizing carbonyl sulfide

Abstract

The present invention relates to a method and an apparatus for synthesizing a carbonyl sulfide, and more particularly, to: a method for synthesizing a carbonyl sulfide, the method comprising the steps of: obtaining a mixed gas containing a carbonyl sulfide by contacting sulfur in at least one form of a liquid phase and a gas phase with carbon monoxide (CO), and further converting unreacted sulfur and carbon monoxide into carbonyl sulfides by contacting the mixed gas with a sulfuration catalyst, wherein the sulfuration catalyst comprises molybdenum (Mo) as a major active metal; and an apparatus for synthesizing carbonyl sulfides, the apparatus comprising a gas-liquid reactor for obtaining a mixed gas comprising carbonyl sulfides by contacting carbon monoxide (CO) with sulfur in at least one form of a liquid phase and a gas phase, and a catalytic reactor for further converting unreacted sulfur and carbon monoxide into carbonyl sulfides by bringing the mixed gas into contact with a sulfuration catalyst, wherein the catalytic reactor contains a sulfuration catalyst containing molybdenum (Mo) as a main active metal.

Description

Technical Field

[0001] The present disclosure relates to a method and apparatus for synthesizing carbonyl sulfide, which is a main raw material for various chemical products, and more particularly, to a method and apparatus for synthesizing carbonyl sulfide using a catalyst containing molybdenum (Mo) as a main active metal. Background Art

[0002] Carbonyl sulfide (COS) is widely used as a main raw material for pesticides, pharmaceuticals, and various chemical products due to its unique molecular structure with two double bonds. In particular, carbonyl sulfide (COS) is known as a useful gas for forming a carbon hard mask in a semiconductor etching process. Specifically, recently, it has been reported that when carbonyl sulfide is used in combination with existing etching gases in an etching process, which can be regarded as the most important process in semiconductor manufacturing, the etching characteristics can be greatly improved, and it is a useful substance that has received a great deal of attention as an etching gas material for next-generation semiconductor processes.

[0003] Such carbonyl sulfide (COS) is generally manufactured using carbon monoxide and sulfur as raw materials. Regarding methods for synthesizing carbonyl sulfide using carbon monoxide and sulfur as raw materials, many methods have been proposed so far. Generally, methods for manufacturing COS are known, including a method of reacting carbon monoxide (CO) and liquid sulfur in a catalyst-free system under high-temperature conditions, a method of reacting carbon monoxide (CO) and liquid sulfur in a catalyst-containing system under medium-temperature conditions, and a method of reacting carbon dioxide (CO2) and carbon disulfide (CS2) in the presence of a catalyst.

[0004] For example, U.S. Patent No. 4,078,045 discloses a method of heating supplied sulfur to form a gas, mixing gaseous sulfur and carbon monoxide to form a mixed gas, and supplying the mixed gas to a reactor to synthesize carbonyl sulfide. This method proposes a technique for synthesizing carbonyl sulfide without using a catalyst. However, the raw material mixing device for heating sulfur to form a gas and mixing sulfur gas and carbon monoxide, and the reaction device for receiving the mixed gas containing sulfur and carbon monoxide and reacting them are independent, so the cost of the equipment is high, and a large amount of energy is required to maintain their respective temperatures, which is not economically desirable and is a factor increasing the manufacturing cost.

[0005] Therefore, methods applying catalysts have been proposed, but there are problems such as insufficient conversion rates that may not be exhibited even under catalyst conditions, and on the other hand, using CO 2 and CS 2The method has the problem of low selectivity due to difficulties in controlling side reactions. Therefore, when a catalyst that can promote sulfidation in the catalytic reaction of CO and sulfur and thereby improve productivity is provided, it is expected to be widely used in related fields. Summary of the Invention

[0006] Technical Problem

[0007] One aspect of the present disclosure is to solve the problems of the related art in synthesizing carbonyl sulfide using carbon monoxide and sulfur as raw materials, and to provide a method for economically and technically synthesizing carbonyl sulfide.

[0008] Another aspect of the present disclosure is to provide an apparatus that can be applied to the synthesis of carbonyl sulfide.

[0009] Technical Solution

[0010] According to one aspect of the present disclosure, a method for synthesizing carbonyl sulfide includes an operation of contacting carbon monoxide (CO) with sulfur in at least one of a liquid phase and a gas phase and obtaining a mixed gas containing carbonyl sulfide; and an operation of contacting the mixed gas with a sulfidation catalyst and further converting unreacted sulfur and carbon monoxide into carbonyl sulfide, wherein the sulfidation catalyst contains molybdenum (Mo) as a main active metal.

[0011] According to another aspect of the present disclosure, an apparatus for synthesizing carbonyl sulfide includes: a gas-liquid reactor for contacting carbon monoxide (CO) and sulfur in at least one of a liquid phase and a gas phase and obtaining a mixed gas containing carbonyl sulfide; and a catalytic reactor for contacting the mixed gas with a sulfidation catalyst and further converting unreacted sulfur and carbon monoxide into carbonyl sulfide, wherein the catalytic reactor contains a sulfidation catalyst containing molybdenum (Mo) as a main active metal.

[0012] Advantageous Effects

[0013] According to the present disclosure, carbonyl sulfide gas can be economically and efficiently synthesized with an improved synthesis rate. The present disclosure can improve the COS conversion rate by adsorbing unreacted sulfur using an easily sulfidated catalyst and increasing its reactivity with CO by utilizing the catalyst activation energy. In addition, by enabling the operation of the catalyst at a low temperature, by-products generated at high temperatures such as H 2 S, CS 2 , CO 2 , SO 2 , etc. can be suppressed, thereby producing high-purity COS. Brief Description of the Drawings

[0014] Figure 1Schematically shows the process of the method for synthesizing carbonyl sulfide according to the present disclosure.

[0015] Figure 2 Schematically shows an exemplary apparatus for synthesizing carbonyl sulfide according to the present disclosure. Detailed Description

[0016] Hereinafter, exemplary embodiments of the present disclosure will be described with reference to the accompanying drawings. However, the embodiments of the present disclosure can be modified in many other forms, and the scope of the present disclosure is not limited to the embodiments described below.

[0017] According to the present disclosure, there are provided a method and an apparatus for synthesizing carbonyl sulfide with improved selectivity and yield.

[0018] More specifically, the method for synthesizing carbonyl sulfide according to the present disclosure includes an operation of contacting carbon monoxide (CO) with sulfur in at least one of a liquid phase and a gas phase to obtain a mixed gas containing carbonyl sulfide; and an operation of contacting the mixed gas with a sulfurization catalyst to further convert unreacted sulfur and carbon monoxide into carbonyl sulfide, wherein the sulfurization catalyst contains molybdenum (Mo) as a main active metal.

[0019] Sulfur in at least one of a liquid phase and a gas phase can be provided by heating solid sulfur, and at this time, the sulfur can be in a liquid phase or a mixture of a liquid phase and a gas phase. For example, solid sulfur can be heated to a temperature equal to or higher than its melting point (e.g., 112.8 °C or higher at 1 standard atmosphere) to provide liquid sulfur or fluidized sulfur containing a liquid phase and a gas phase. The sulfur can be heated in a sulfur reaction tank (10) to remove moisture, etc. in the gas phase, and purged with N2 to improve its purity.

[0020] Contact the fluidized sulfur and CO to obtain a mixed gas containing carbonyl sulfide, and at this time, the mixing method is not particularly limited. However, for example, CO can be bubbled into liquid sulfur in a gas-liquid reactor (20) to contact the liquid sulfur in the form of bubbles, thereby converting the liquid sulfur into carbonyl sulfide. As Figure 1 schematically shown, as a result, the unreacted CO and S are subsequently additionally converted into carbonyl sulfide using a sulfurization catalyst. Thereafter, trace amounts of unreacted substances and by-products can be separated and purified to produce high-purity COS. At this time, the by-products can include H 2 S, CS 2 2, SO 2 2, CO 2At least one of the above, and the unreacted product may include at least one of CO, gaseous S, etc. As a technique for its removal, for example, after lowering the temperature to convert gaseous S into a liquid phase or a solid phase, it can be separated by a filter, and the remaining substance can be separated from COS by low-temperature distillation (for example, distillation at -70°C to 0°C).

[0021] Meanwhile, in the operation of obtaining the mixed gas, it is preferable to supply sulfur at a temperature of 350°C to 500°C, so the gas-liquid reactor (20) can also be maintained within this temperature range. The temperature of sulfur can be, for example, 400°C to 450°C, preferably 400°C to 444°C. When sulfur is provided at a temperature within the above range, a high COS conversion rate can be obtained.

[0022] Meanwhile, in the operation of obtaining the mixed gas, carbon monoxide can be supplied at a flow rate of 5 ml / min to 10 ml / min, for example, it can be supplied at a flow rate of 5 ml / min to 8 ml / min. When carbon monoxide is supplied at a flow rate within the above range, a high COS conversion rate can be obtained.

[0023] In addition, the mixed gas obtained by the operation of obtaining the mixed gas can be further converted into carbonyl sulfide by an operation with a residence time of 30 seconds to 5 minutes. This operation can be carried out, for example, in a retention reactor (30), and when a residence time within the above range is given, a more improved COS conversion rate can be obtained.

[0024] Thereafter, the present disclosure includes an operation of bringing the mixed gas into contact with a sulfide catalyst to further convert unreacted sulfur and carbon monoxide into carbonyl sulfide. At this time, the sulfide catalyst that can be used in the present disclosure contains molybdenum (Mo) (transition metal) as the main active metal to increase the COS synthesis rate, and since the electrons are pentavalent (5+) and form relatively weak bonds with sulfur, in the case of continuously supplying sulfur, the sulfur and CO adsorbed on Mo reduce the activation energy through the catalyst to promote the reaction, so that the conversion to COS proceeds well, and the converted sulfur is continuously supplied in the raw material, so it reacts with Mo to become a sulfide, and the catalytic active sites can be maintained.

[0025] In the operation of bringing the mixed gas into contact with a sulfide catalyst to further convert unreacted sulfur and carbon monoxide into carbonyl sulfide, components generated as side reactions, such as H 2 S, SO 2 、CS 2 etc. can also be converted into carbonyl sulfide under the catalyst.

[0026] Meanwhile, the sulfurization catalyst may be a catalyst supported on at least one porous carrier selected from silica, alumina, and titanium dioxide and containing at least one selected from cobalt, nickel, and tungsten as a promoter. For example, the sulfurization catalyst may be supported on an alumina carrier, contain manganese as the main active metal, and contain at least one selected from cobalt and nickel as a promoter.

[0027] In addition, the method for synthesizing carbonyl sulfide according to the present disclosure may additionally include an operation of cooling the resultant obtained in the operation of further converting through a sulfurization catalyst to a temperature lower than the boiling point of sulfur to separate liquid sulfur into gas and liquid. The liquid sulfur thus produced can be recycled as a raw material.

[0028] Subsequently, the gas from which sulfur has been removed by the operation of separating sulfur into gas and liquid may be a mixed gas containing COS and CO, and the trace sulfur dust, etc. contained in the mixed gas can be purified through a filter. Furthermore, carbonyl sulfide can be separated and obtained from the gas containing COS and CO by boiling point separation (i.e., at a temperature equal to or higher than the boiling point of CO and lower than the boiling point of COS). More specifically, CO and liquid COS can be separated into the gaseous state at a temperature of -139°C to -51°C under 1 standard atmosphere.

[0029] According to another aspect of the present disclosure, there is provided an apparatus for synthesizing carbonyl sulfide. The content described in the above method for synthesizing carbonyl sulfide is equally applicable to the apparatus for synthesizing carbonyl sulfide according to the present disclosure.

[0030] The apparatus for synthesizing carbonyl sulfide according to the present disclosure includes: a gas-liquid reactor (20) for bringing carbon monoxide (CO) into contact with sulfur in at least one of a liquid phase and a gas phase to obtain a mixed gas containing carbonyl sulfide; and a catalytic reactor (40) for bringing the mixed gas into contact with a sulfurization catalyst to further convert unreacted sulfur and carbon monoxide into carbonyl sulfide, and the catalytic reactor contains a sulfurization catalyst containing molybdenum (Mo) as the main active metal.

[0031] Figure 2 An exemplary apparatus for synthesizing carbonyl sulfide according to the present disclosure is shown.

[0032] The apparatus for synthesizing carbonyl sulfide according to the present disclosure may further include a sulfur reaction tank (10) for supplying sulfur. As described above, the temperature of solid sulfur in the sulfur reaction tank can be raised to a temperature at which the solid sulfur can be converted into a liquid phase or a mixture of a liquid phase and a gas phase, and the sulfur whose temperature has been raised in the sulfur reaction tank can be supplied to the gas-liquid reactor. In addition, moisture, etc. can be removed as a gas by heating in the sulfur reaction tank (10), and purged with N2 to improve the purity of sulfur.

[0033] In a gas-liquid reactor (20), a mixed gas containing carbonyl sulfide is obtained by bringing CO into contact with sulfur in a fluidized phase, and as Figure 2 shown, for example, CO can be bubbled into liquid sulfur in the gas-liquid reactor (20) to contact the liquid sulfur in the form of bubbles and be converted into carbonyl sulfide. In Figure 2 , CO is shown as being injected from the top, but this is an example, and CO can be supplied by bubbling from the bottom of the liquid sulfur. In this way, the unreacted CO and S in the gas-liquid reactor are subsequently converted into carbonyl sulfide using a sulfurization catalyst.

[0034] Furthermore, a retention reactor (30) is provided downstream of the gas-liquid reactor (20) and upstream of the catalytic reactor (40) that can retain the mixed gas discharged from the gas-liquid reactor, such that the mixed gas can be additionally converted into carbonyl sulfide.

[0035] Furthermore, the apparatus for synthesizing carbonyl sulfide of the present disclosure additionally includes a condenser (50), for example, a condenser provided downstream of the catalytic reactor (40) and cooling the resulting product discharged from the catalytic reactor to a temperature below the melting point of sulfur to separate the liquid sulfur into gas and liquid, such that an operation of reducing the temperature of the condenser to a temperature below the boiling point of sulfur to separate the liquid sulfur into gas and liquid can be performed. As Figure 2 shown, the liquid sulfur thus produced can be reintroduced into the sulfur reaction tank (10) and recycled as a raw material.

[0036] The gas from which sulfur is removed in the condenser in the liquid phase can be a mixed gas containing COS and CO, and trace amounts of sulfur dust, etc. contained in the mixed gas can be purified by an optional additional filter (60), and furthermore, a cold box (70) for obtaining liquid carbonyl sulfide by boiling point separation from the gas discharged from the condenser can be additionally included downstream of the condenser, and through the cold box (70), liquid carbonyl sulfide can be obtained by boiling point separation from the gas containing COS and CO at a temperature equal to or higher than the boiling point of CO and lower than the boiling point of COS.

[0037] Hereinafter, the present disclosure will be described in more detail by way of detailed examples. The following examples are only examples to assist in understanding the present disclosure, and the scope of the present disclosure is not limited thereto.

[0038] Embodiments of the Invention

[0039] Examples

[0040] 1. Synthesis of Carbonyl Sulfide

[0041] Solid sulfur is heated to 200 °C to 500 °C to prepare sulfur in the form of liquid phase and / or gas phase to be stored in a sulfur reaction tank. Then, CO is supplied to the reaction tank at a flow rate of 5 ml / min to 100 ml / min and brought into contact with sulfur to be converted into COS. Then, unreacted CO and S alone are additionally converted into COS using a sulfide catalyst at 170 °C to 300 °C. Thereafter, a small amount of unreacted substances and by-products are separated and purified to produce high-purity COS. This process is schematically shown in Figure 1 in. At this time, by-products after the reaction can be produced as H 2 S, CS 2 , SO 2 and CO 2 , but the amount is so small that it is determined that separation is not required. Meanwhile, unreacted raw material CO and S can be additionally separated as needed. For example, S can be separated by lowering the temperature of S to room temperature, converting it into a solid phase, and then filtering through a filter, and CO can be analyzed together with the product to measure the residual amount.

[0042] The above reaction is carried out in a reaction system schematically shown in Figure 2 . More specifically, solid elemental sulfur is heated to 120 °C to 150 °C so that it can be transferred from the sulfur reaction tank (10), and its purity is improved by purging with N2 to remove moisture and the like contained as a gas phase. In addition, when purging with N2 to remove H 2 O contained in S, since the temperature inside the chamber is 120 °C to 150 °C, H 2 O and S can react to produce H 2 S. Although this is suitable for the atmospheric emission level, it is desirable to treat and transfer it as an odorous substance, so H 2 S can be removed by a scrubber.

[0043] Liquid and / or gaseous sulfur is continuously supplied to a gas-liquid reactor (20). The supplied sulfur is heated to a reaction temperature of 200 °C to 500 °C for the first reaction with CO, and CO is supplied to the inside of the reactor from the top to utilize the heat from the upper end of the reactor. Gaseous CO and liquid sulfur react in a bubble form (bubbling) contact mode to produce COS at once.

[0044] Unreacted CO and vaporized sulfur move together through a retention reactor (30) to produce COS for the second time. Thereafter, they pass through a catalytic reactor (40) at 170 °C to 300 °C to produce COS for the third time, and impurities such as H 2 S, SO 2 , CS 2Etc. are converted to COS through the catalyst. The main role of the catalyst is to convert the residual CO and S into COS, and the impurities are converted to COS through various reactions occurring in the catalyst, including the following.

[0045] H 2 S + CO → COS + H 2

[0046] SO 2 + CO → COS + O 2

[0047] CS 2 + H 2 O → COS + H 2 S

[0048] However, at this time, it was determined that the impurity concentration was so low that measurement was not required. Meanwhile, sulfur was recovered in the liquid phase by reducing sulfur to below 112.8 °C (which is the liquid temperature of sulfur at 1 standard atmosphere) in the condenser (50), and a small amount of sulfur dust was separated by the filter (60). Finally, unreacted CO was separated in the cold box (70) by the boiling point temperature separation of COS and CO to produce high-purity COS.

[0049] 2. According to the results of the synthesis conditions of carbonyl sulfide

[0050] (1) Regarding the influence of pretreatment

[0051] N 2 was purged into the sulfur reaction tank (10) of the sulfur liquefaction tank at Figure 2 , and the discharged gas was measured with an analyzer, and pretreatment was carried out to reduce the H 2 O concentration and make the moisture contained in the liquid sulfur close to 0. By doing so, it is possible to remove H 2 S, SO 2 , CO 2 etc., which are the reasons for generating impurities, so as to increase the COS concentration and reduce the purification and separation equipment for high purity. 2 O, thereby increasing the COS concentration and reducing the purification and separation equipment for high purity.

[0052] [Table 1]

[0053]

[0054] (2) According to the influence of sulfur temperature

[0055] The final CO volume % and COS volume % according to the temperature of sulfur supplied to the gas-liquid reactor (20) are shown in Table 2 below.

[0056] [Table 2]

[0057]

[0058] (3) Influence of CO Flow Rate and Retention Time

[0059] The composition of the final mixed gas according to the flow rate of the supplied CO and its retention time in the retention reactor (30) is shown in Table 3 below.

[0060] [Table 3]

[0061]

[0062] (4) Influence According to Catalyst Type and Conditions

[0063] The composition of the final mixed gas according to the type of catalyst supplied to the catalytic reactor (40), the temperature of the catalytic reactor (40), and the catalyst space velocity is shown in Table 4, Table 5, and Table 6 below, respectively. At this time, the catalyst space velocity is the value obtained by dividing the amount of gas that the catalyst can process per hour (Nm 3 / h) by the catalyst loading amount (m 3 ), which means the amount of gas that a unit amount of catalyst can process per hour and is a value corresponding to the physical characteristics of the catalyst itself.

[0064] Here, the space velocity (Vs) corresponds to the characteristic determined by measurement under standard conditions (e.g., 0 degrees Celsius, 1 standard atmosphere (in Nm 3 ), where N means "standard")). Therefore, when using the space velocity (Vs) to calculate the amount of catalyst, the actual exhaust gas flow rate (Mex) is converted to the exhaust gas flow rate under standard conditions and calculated. At this time, the space velocity is the feed gas treatment flow rate per unit volume of the catalyst, e.g., flow rate (ml / min) / catalyst volume (ml), and the unit is only retained as hour -1 . The space velocity can be changed by increasing the feed flow rate of the same amount of catalyst or by adjusting the amount of catalyst, and in this experiment, the flow rate is changed for adjustment.

[0065] [Table 4]

[0066]

[0067] [Table 5]

[0068]

[0069]

[0070] [Table 6]

[0071]

[0072] Although the embodiments of the present disclosure have been described in detail above, the scope of the present disclosure is not limited thereto, and it will be apparent to those skilled in the art that various modifications and changes are possible without departing from the technical spirit of the present disclosure described in the claims.

[0073] Description of Reference Numerals

[0074] 10: Sulfur Reactor

[0075] 20: Gas-Liquid Reactor

[0076] 30: Holding Reactor

[0077] 40: Catalytic Reactor

[0078] 50: Condenser

[0079] 60: Filter

[0080] 70: Cold Box

Claims

1. A method for synthesizing carbonyl sulfide, comprising: an operation of bringing carbon monoxide (CO) into contact with sulfur in at least one of a liquid phase and a gas phase to obtain a mixed gas containing carbonyl sulfide; and an operation of bringing the mixed gas into contact with a sulfurization catalyst and further converting unreacted sulfur and carbon monoxide into carbonyl sulfide, wherein the sulfurization catalyst contains molybdenum (Mo) as a main active metal.

2. The method for synthesizing carbonyl sulfide according to claim 1, further comprising an operation of retaining the mixed gas obtained by the operation of obtaining the mixed gas for a retention time of 30 seconds to 5 minutes before the operation of further converting it into the carbonyl sulfide.

3. The method for synthesizing carbonyl sulfide according to claim 1, wherein the sulfur in the operation of obtaining the mixed gas is supplied at a temperature of 350°C to 500°C.

4. The method for synthesizing carbonyl sulfide according to claim 1, wherein the sulfurization catalyst is a catalyst supported on at least one porous support selected from silica, alumina, and titanium dioxide and containing at least one of cobalt, nickel, and tungsten as a promoter.

5. The method for synthesizing carbonyl sulfide according to claim 1, further comprising an operation of cooling the product obtained in the operation of further converting it into the carbonyl sulfide to a temperature lower than the boiling point of sulfur and separating the liquid sulfur into gas and liquid.

6. The method for synthesizing carbonyl sulfide according to claim 5, further comprising an operation of obtaining liquid carbonyl sulfide by boiling point separation from the gas obtained from the operation of separating sulfur into gas and liquid.

7. An apparatus for synthesizing carbonyl sulfide, comprising: a gas-liquid reactor for bringing carbon monoxide (CO) into contact with sulfur in at least one of a liquid phase and a gas phase to obtain a mixed gas containing carbonyl sulfide; and a catalytic reactor for bringing the mixed gas into contact with a sulfurization catalyst and further converting unreacted sulfur and carbon monoxide into carbonyl sulfide, wherein the catalytic reactor contains a sulfurization catalyst containing molybdenum (Mo) as a main active metal.

8. The apparatus for synthesizing carbonyl sulfide according to claim 7, further comprising a sulfur reaction tank for supplying the sulfur.

9. The apparatus for synthesizing carbonyl sulfide according to claim 7, further comprising a retention reactor provided downstream of the gas-liquid reactor and upstream of the catalytic reactor and capable of retaining the mixed gas discharged from the gas-liquid reactor.

10. The apparatus for synthesizing carbonyl sulfide according to claim 7, further comprising a condenser provided downstream of the catalytic reactor, cooling the product discharged from the catalytic reactor to a temperature lower than the boiling point of sulfur, and separating the liquid sulfur into gas and liquid.

11. The apparatus for synthesizing carbonyl sulfide according to claim 10, further comprising a cold box provided downstream of the condenser for obtaining liquid carbonyl sulfide by boiling point separation from the gas discharged from the condenser.

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