Method and apparatus for synthesizing carbonyl sulfide

Abstract

The present invention relates to a method and apparatus for synthesizing carbonyl sulfide, more particularly, to a method for synthesizing carbonyl sulfide, the method comprising: contacting sulfur in at least one of liquid and gas phases with carbon monoxide (CO) to obtain a gas mixture containing carbonyl sulfide; and contacting the gas mixture with a sulfurization catalyst containing molybdenum (Mo) as a main active metal to convert unreacted sulfur and carbon monoxide into carbonyl sulfide. The present invention also relates to an apparatus for synthesizing carbonyl sulfide, the apparatus comprising: a gas-liquid reactor for contacting sulfur in at least one of liquid and gas phases with carbon monoxide (CO) to obtain a gas mixture containing carbonyl sulfide; and a catalytic reactor for contacting the gas mixture with a sulfurization catalyst containing molybdenum (Mo) as a main active metal to convert unreacted sulfur and carbon monoxide into carbonyl sulfide.

Description

[Technical Field]

[0001] The present invention relates to a method and apparatus for synthesizing carbonyl sulfide, which is used as 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 the main active metal. [Background technology]

[0002] Carbonyl sulfide (COS) is widely used as a main raw material for pesticides, pharmaceuticals, and various other chemical products due to its unique molecular structure with two double bonds. In particular, carbonyl sulfide (COS) is known as a useful gas for carbon hard masks in semiconductor etching processes. Recently, results have been published showing that COS can significantly improve etching characteristics when used in combination with existing etching gases in the etching process, which is considered to be the most important step in semiconductor manufacturing. As a result, COS is a useful substance that is attracting much attention as an etching gas material for next-generation semiconductor processes.

[0003] Carbonyl sulfide (COS) is usually produced using carbon monoxide and sulfur as raw materials. Many methods have been proposed for synthesizing carbonyl sulfide using carbon monoxide and sulfur as raw materials. Generally, COS is produced by reacting carbon monoxide (CO) with liquid-phase sulfur under high-temperature conditions in a system without a catalyst, by reacting carbon monoxide (CO) with liquid-phase sulfur under medium-temperature conditions in a system with a catalyst, or by reacting carbon dioxide (CO2) with carbon disulfide (CS2) in the presence of a catalyst.

[0004] For example, U.S. Pat. No. 4,078,045 discloses a method for synthesizing carbonyl sulfide by heating supplied sulfur to form a gas, mixing the gaseous sulfur with carbon monoxide to form a mixed gas, and supplying the mixed gas to a reactor. This method presents a technology that enables carbonyl sulfide to be synthesized without using a catalyst, but the raw material mixing device that heats sulfur to form a gas and mixes the gaseous sulfur with carbon monoxide, and the reactor that receives the supplied mixed gas of sulfur and carbon monoxide and reacts them, are separate devices. This results in high equipment costs and requires a large amount of energy to maintain the respective temperatures, making it economically undesirable and resulting in increased production costs.

[0005] Therefore, methods that use catalysts have been proposed, but they have the problem of not being able to achieve a sufficient conversion rate even in the presence of a catalyst, while methods that use CO2 and CS2 have the problem of difficulty in controlling side reactions and low selectivity. Therefore, if a catalyst that can facilitate sulfurization in the catalytic reaction of CO and sulfur and increase the production rate is provided, it is expected to be widely applicable in related fields. Summary of the Invention [Problem to be solved by the invention]

[0006] One aspect of the present invention is to solve the problems of the prior art when synthesizing carbonyl sulfide using carbon monoxide and sulfur as raw materials, and to provide a method for synthesizing carbonyl sulfide economically and technically.

[0007] Another aspect of the present invention is to provide an apparatus applicable to the synthesis of carbonyl sulfide. [Means for solving the problem]

[0008] According to one aspect of the present invention, there is provided a method for synthesizing carbonyl sulfide, the method comprising: contacting sulfur in at least one of a liquid phase and a gas phase with carbon monoxide (CO) to obtain a gas mixture containing carbonyl sulfide; and contacting the gas mixture 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.

[0009] According to another aspect of the present invention, there is provided an apparatus for synthesizing carbonyl sulfide, comprising: a gas-liquid reactor that contacts sulfur in at least one of a liquid phase and a gas phase with carbon monoxide (CO) to obtain a mixed gas containing carbonyl sulfide; and a catalytic reactor that contacts the mixed gas with a sulfurization catalyst to further convert unreacted sulfur and carbon monoxide into carbonyl sulfide, wherein the catalytic reactor comprises a sulfurization catalyst containing molybdenum (Mo) as a main active metal. [Effects of the Invention]

[0010] According to the present invention, carbonyl sulfide gas can be synthesized economically and efficiently at an improved synthesis rate. The present invention uses a catalyst that is easily sulfided, which adsorbs unreacted sulfur and uses catalyst activation energy to increase the reactivity with CO, thereby improving the COS conversion rate. Furthermore, by enabling the catalyst to operate at low temperatures, the generation of by-products such as H2S, CS2, CO2, and SO2, which are generated at high temperatures, can be suppressed, allowing for the production of high-purity COS. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic diagram showing steps of the method for synthesizing carbonyl sulfide of the present invention. [Figure 2] 1 is a schematic diagram of an exemplary carbonyl sulfide synthesis apparatus of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0012] The present invention will be described in detail below with reference to the accompanying drawings, in which: FIG. 1 is a block diagram of a semiconductor device according to a first embodiment of the present invention; FIG. 2 is a block diagram of a semiconductor device according to a first embodiment of the present invention; FIG. 3 is a block diagram of a semiconductor device according to a first embodiment of the present invention;

[0013] According to the present invention, a method and apparatus for synthesizing carbonyl sulfide with improved selectivity and yield are provided.

[0014] More specifically, the method for synthesizing carbonyl sulfide of the present invention includes the steps of: contacting sulfur in at least one of a liquid phase and a gas phase with carbon monoxide (CO) to obtain a mixed gas containing carbonyl sulfide; and contacting the mixed gas with a sulfurization catalyst to further convert unreacted sulfur and carbon monoxide into carbonyl sulfide, the sulfurization catalyst containing molybdenum (Mo) as a main active metal.

[0015] Sulfur in at least one of liquid and gas phases can be produced by heating solid sulfur, which may be in liquid phase or a mixture of liquid and gas phases. For example, solid sulfur can be heated to a temperature above its melting point, e.g., 112.8°C or higher at 1 atmosphere, to produce liquid sulfur or fluid phase sulfur containing liquid and gas phases. The sulfur can be heated in the sulfur reactor 10 to remove moisture and other impurities as a gas, and then purged with N2 to increase its purity.

[0016] The fluid-phase sulfur and CO are contacted to obtain a gas mixture containing carbonyl sulfide. The mixing method is not particularly limited. For example, CO can be converted to carbonyl sulfide by bubbling CO into liquid-phase sulfur in a gas-liquid reactor 20. As shown in FIG. 1, the resulting unreacted CO and S are subsequently converted to carbonyl sulfide using a sulfurization catalyst. High-purity COS can then be produced by separating and purifying trace amounts of unreacted materials and by-products. The by-products include at least one of H2S, CS2, SO2, and CO2, while the unreacted materials include at least one of CO and gas-phase S. To remove these materials, for example, the gas-phase S can be converted to a liquid or solid phase by lowering its temperature and then separated through a filter. The remaining materials can be separated from the COS by low-temperature distillation, e.g., at a temperature of -70 to 0°C.

[0017] Meanwhile, in the step of obtaining the mixed gas, sulfur is preferably supplied at a temperature of 350 to 500°C, so that the gas-liquid reactor 20 can also be maintained within this temperature range. The sulfur may have a temperature of, for example, 400 to 450°C, preferably 400 to 444°C. When sulfur is provided at a temperature within this range, a high COS conversion rate can be obtained.

[0018] In addition, the carbon monoxide in the step of obtaining the mixed gas may be supplied at a flow rate of 5 to 10 ml / min, for example, 5 to 8 ml / min. When carbon monoxide is supplied at a flow rate within this range, a high COS conversion rate can be obtained.

[0019] Furthermore, the gas mixture obtained in the gas mixture obtaining step can be further converted to carbonyl sulfide by a residence time of 30 seconds to 5 minutes. This step can be performed, for example, in a residence reactor 30, and a more improved COS conversion rate can be obtained when the residence time is within the above range.

[0020] The present invention then includes a step of contacting the gas mixture with a sulfurization catalyst to further convert unreacted sulfur and carbon monoxide into carbonyl sulfide. The sulfurization catalyst that can be used in the present invention contains molybdenum (Mo), a transition metal, as the main active metal to increase the synthesis rate of COS. Mo has a valence of five electrons (5+) and forms a relatively weak bond with sulfur. Under conditions where sulfur is continuously supplied, the sulfur and CO adsorbed on Mo act as a catalyst to lower the activation energy, facilitating the reaction and facilitating the conversion to COS. As the converted sulfur is continuously supplied to the raw material, it reacts with Mo to be sulfurized, thereby maintaining catalytic active sites.

[0021] In the step of contacting the mixed gas with a sulfurization catalyst to further convert unreacted sulfur and carbon monoxide into carbonyl sulfide, components such as H2S, SO2, and CS2 generated by side reactions can also be converted into carbonyl sulfide in the presence of the catalyst.

[0022] Meanwhile, the sulfide catalyst may be a catalyst supported on at least one porous support selected from the group consisting of silica, alumina, and titania, and containing at least one promoter selected from the group consisting of cobalt, nickel, and tungsten. For example, the sulfide catalyst may be supported on an alumina support, contain manganese as a main active metal, and contain at least one promoter selected from the group consisting of cobalt and nickel.

[0023] Furthermore, the method for synthesizing carbonyl sulfide of the present invention may further include a step of cooling the resultant obtained from the step of further converting with the sulfurization catalyst to a temperature below the boiling point of sulfur, and separating the liquid sulfur into gas and liquid. The liquid sulfur thus produced can be recycled as a raw material.

[0024] The gas from which sulfur has been removed by the subsequent gas-liquid separation of sulfur may be a mixed gas containing COS and CO. Trace amounts of sulfur dust contained in the mixed gas can be purified using a filter, and carbonyl sulfide can be separated from the gas containing COS and CO by boiling point separation, i.e., at a temperature above the boiling point of CO and below the boiling point of COS. More specifically, CO can be separated into a gas phase from liquid COS at a temperature of -139 to -51°C under 1 atmosphere.

[0025] According to another aspect of the present invention, there is provided an apparatus for synthesizing carbonyl sulfide. The contents described above regarding the method for synthesizing carbonyl sulfide also apply to the apparatus for synthesizing carbonyl sulfide of the present invention.

[0026] The apparatus for synthesizing carbonyl sulfide of the present invention includes a gas-liquid reactor 20 that contacts sulfur in at least one of liquid and gas phases with carbon monoxide (CO) to obtain a mixed gas containing carbonyl sulfide; and a catalytic reactor 40 that contacts the mixed gas with a sulfurization catalyst to further convert unreacted sulfur and carbon monoxide into carbonyl sulfide, the catalytic reactor containing a sulfurization catalyst containing molybdenum (Mo) as a main active metal.

[0027] An exemplary apparatus for synthesizing carbonyl sulfide according to the present invention is shown in FIG.

[0028] The carbonyl sulfide synthesis apparatus of the present invention may further include a sulfur reactor 10 for supplying the sulfur. In the sulfur reactor, as described above, the solid sulfur can be heated to a temperature at which it can be converted into a liquid phase or a mixture of liquid and gas phases, and the sulfur whose temperature has been increased in the sulfur reactor can be supplied to a gas-liquid reactor. In addition, the sulfur reactor 10 can be heated to remove moisture and other gas phase substances, and the purity of the sulfur can be increased by purging with N2.

[0029] In the gas-liquid reactor 20, fluid-phase sulfur and CO are contacted to obtain a mixed gas containing carbonyl sulfide. As shown in Figure 2, for example, CO can be bubbled into the liquid-phase sulfur in the gas-liquid reactor 20 to contact the sulfur in the form of gas bubbles, thereby converting the gas into carbonyl sulfide. While Figure 2 shows CO being introduced from the top, this is merely an example, and CO may also be supplied by bubbling into the bottom of the liquid-phase sulfur. The unreacted CO and S in the gas-liquid reactor are subsequently converted into carbonyl sulfide using a sulfurization catalyst.

[0030] Additionally, a retention reactor 30 is provided at the rear end of the gas-liquid reactor 20 and the front end of the catalytic reactor 40, and is capable of retaining the mixed gas discharged from the gas-liquid reactor, thereby allowing further conversion into carbonyl sulfide.

[0031] Furthermore, the carbonyl sulfide synthesis apparatus of the present invention may further include a condenser 50, i.e., a condenser, disposed at the rear end of the catalytic reactor 40, which cools the product discharged from the catalytic reactor to a temperature below the melting point of sulfur and separates the liquid sulfur into gas and liquid. The condenser may also perform a step of lowering the temperature of the condenser to a temperature below the boiling point of sulfur to separate the liquid sulfur into gas and liquid. The liquid sulfur thus produced may be reintroduced into the sulfur reactor 10 as shown in FIG. 2 and recycled as a feedstock.

[0032] The gas from which sulfur has been removed as a liquid phase from the condenser may be a mixed gas containing COS and CO. Trace amounts of sulfur dust contained in the mixed gas may be purified using an optional additional filter 60. The condenser may further include a cooling reactor 70 disposed at the rear end of the condenser for obtaining liquid carbonyl sulfide from the gas discharged from the condenser by boiling point separation. The cooling reactor 70 may obtain liquid carbonyl sulfide from the gas containing COS and CO by boiling point separation at a temperature equal to or higher than the boiling point of CO and lower than the boiling point of COS.

[0033] The present invention will be described in more detail with reference to the following specific examples. The following examples are merely illustrative examples to aid in understanding the present invention, and are not intended to limit the scope of the present invention. [Example]

[0034] Example 1. Synthesis of carbonyl sulfide Solid sulfur was heated to 200-500°C to obtain liquid and / or gaseous sulfur, which was then stored in a sulfur reactor. CO was then supplied to the reactor at a flow rate of 5-100 ml / min and converted to COS by contact with the sulfur. The separated unreacted CO and S were then further converted to COS at 170-300°C using a sulfurization catalyst. Trace amounts of unreacted materials and by-products were then separated and purified to produce high-purity COS. This process is shown diagrammatically in Figure 1. The by-products generated after the reaction include H2S, CS2, SO2, and CO2, but their amounts were so small that separation was not necessary. If necessary, the unreacted raw materials CO and S can be further separated. For example, S can be converted to a solid phase by lowering the temperature to room temperature and then filtered. The remaining CO can be analyzed together with the product to determine its amount.

[0035] The above reaction was carried out in the reaction system shown diagrammatically in Figure 2. More specifically, the solid-phase elemental sulfur in the sulfur reaction vessel 10 was heated to 120-150°C so that it could be transported, and the purity was increased by purging with N2 to remove contained moisture and other gaseous substances. Furthermore, during N2 purging to remove H2O contained in S, the temperature inside the chamber was 120-150°C, so H2O and S reacted to produce H2S. Although this is suitable for atmospheric emission levels, it is preferable to treat and transport it as a malodorous substance, so H2S can be removed using a scrubber.

[0036] Liquid and / or gaseous sulfur is continuously supplied to the gas-liquid reactor 20. The supplied sulfur is heated to a reaction temperature of 200-500°C for the primary reaction with CO, and CO is supplied from the top of the reactor to the interior, utilizing the heat at the top of the reactor. The gaseous CO and liquid sulfur react in a contact manner in the form of bubbles (bubbling) to primarily produce COS.

[0037] Unreacted CO and vaporized sulfur move together through the retention reactor 30, generating secondary COS. They then pass through the catalytic reactor 40 at 170-300°C, generating tertiary COS, and impurities such as H2S, SO2, and CS2 generated by side reactions are converted into COS by the catalyst. The main role of the catalyst is to convert residual CO and S into COS, and impurities are converted to COS through various reactions that occur within the catalyst, including the following:

[0038] H2S+CO→COS+H2 SO2+CO→COS+O2 CS2+H2O→COS+H2S

[0039] However, it was confirmed that the impurity concentration was low enough that measurement was not necessary. Meanwhile, in condenser 50, the pressure is lowered to below 112.8°C, the liquid phase temperature of sulfur, based on 1 atmosphere, to recover the sulfur as a liquid phase, and trace amounts of sulfur dust are separated through filter 60. Finally, unreacted CO is separated in cooling reactor 70 by separation at the boiling point of COS and CO, producing high-purity COS.

[0040] 2. Results depending on carbonyl sulfide synthesis conditions (1) Impact on pretreatment The gas discharged from the sulfur reaction vessel 10 (sulfur liquefaction vessel in Figure 2) was measured with an analyzer after purging with N2, and the H2O concentration was reduced and pre-treated so that the water content in the liquid sulfur was close to zero. This removes H2O, which is a cause of the generation of impurities such as H2S, SO2, and CO2, improving the COS concentration and reducing the need for refining and separation equipment for high purity.

[0041] [Table 1]

[0042] (2) Effect of temperature on sulfur The final CO and COS volume percentages depending on the temperature of the sulfur fed to the gas-liquid reactor 20 are shown in Table 2 below.

[0043] [Table 2]

[0044] (3) Effects of CO flow rate and residence time The composition of the final mixed gas depending on the flow rate of CO supplied and the residence time in the residence reactor 30 is shown in Table 3 below.

[0045] [Table 3]

[0046] (4) Effects of catalyst type and conditions The composition of the final mixed gas depending on the type of catalyst provided in the catalytic reactor 40, the temperature of the catalytic reactor 40, and the catalyst space velocity is shown in Tables 4, 5, and 6 below. Here, the catalyst space velocity is the amount of gas (Nm) that the catalyst can process per hour. 3 / h) is calculated by dividing 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 that corresponds to the physical properties of the catalyst itself.

[0047] Here, the space velocity (Vs) corresponds to the physical property determined by measurement under normal conditions, i.e., 0°C and 1 atm (Nm 3In this case, N stands for "Normal" and the space velocity (Vs) was used to calculate the catalyst amount, and the actual exhaust gas flow rate (Mex) was converted to the normal exhaust gas flow rate. In this case, the space velocity is the processing flow rate of the feed gas per unit volume of the catalyst, that is, the flow rate (ml / min) / catalyst volume (ml), and the unit is h -1 The space velocity can be changed by increasing the feed flow rate for the same catalyst amount or by adjusting the catalyst amount, and in this experiment it was adjusted by changing the flow rate.

[0048] [Table 4]

[0049] [Table 5]

[0050] [Table 6]

[0051] Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and it is obvious to those skilled in the art that various modifications and variations are possible within the scope that does not deviate from the technical idea of ​​the present invention described in the claims. [Explanation of symbols]

[0052] 10: Sulfur reaction tank 20: Gas-liquid reactor 30: Retention Reactor 40: Catalytic reactor 50: Condenser 60: Filter 70:Cold Box

Claims

1. contacting sulfur in at least one of a liquid phase and a gas phase with carbon monoxide (CO) to obtain a gas mixture containing carbonyl sulfide; and contacting the gas mixture with a sulfurization catalyst to further convert unreacted sulfur and carbon monoxide to carbonyl sulfide; The method for synthesizing carbonyl sulfide, wherein the sulfurization catalyst contains molybdenum (Mo) as a main active metal.

2. 2. The method for synthesizing carbonyl sulfide according to claim 1, further comprising retaining the gas mixture obtained in the step of obtaining the gas mixture for a retention time of 30 seconds to 5 minutes before the step of further converting the gas mixture into carbonyl sulfide.

3. 2. The method of claim 1, wherein the sulfur in the step of obtaining the mixed gas is supplied at a temperature of 350 to 500°C.

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

5. 2. The method for synthesizing carbonyl sulfide according to claim 1, further comprising the step of cooling the resultant obtained in the step of further converting to carbonyl sulfide to a temperature below the boiling point of sulfur, and separating the liquid sulfur into gas and liquid.

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

7. a gas-liquid reactor for contacting sulfur in at least one of a liquid phase and a gas phase with carbon monoxide (CO) to obtain a mixed gas containing carbonyl sulfide; and a catalytic reactor in which the mixed gas is contacted with a sulfurization catalyst to further convert unreacted sulfur and carbon monoxide into carbonyl sulfide; The catalytic reactor includes a sulfurization catalyst containing molybdenum (Mo) as a main active metal, and the apparatus for synthesizing carbonyl sulfide includes the sulfurization catalyst containing molybdenum (Mo).

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

9. The apparatus for synthesizing carbonyl sulfide according to claim 7, further comprising a retention reactor disposed at the rear end of the gas-liquid reactor and the front end of the catalytic reactor, 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 disposed at the rear end of the catalytic reactor, for cooling the resultant discharged from the catalytic reactor to a temperature below 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 cooling reactor disposed at a rear end of the condenser, for obtaining liquid carbonyl sulfide from the gas discharged from the condenser by boiling point separation.

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