Process for the production of elemental sulfur by carbonyl sulfide absorption-hydrolysis-oxidation

Abstract

This invention provides a novel process for producing elemental sulfur from carbonyl sulfide (COS) through absorption-hydrolysis-oxidation. The process involves introducing a composite solvent into a bubbling reactor using a centrifugal pump, then passing the COS-containing gas to be treated into the composite solvent. The reaction is carried out using a bubbling absorption method for a period of time. The purified gas, after COS removal, is discharged from the gas outlet at the top of the bubbling reactor. The suspended sulfur generated in the reaction is discharged along with the reacted composite solvent from the waste liquid outlet on the upper side wall of the bubbling reactor. After filtration and dehydration, elemental sulfur is obtained. Compared to existing processes, this novel process eliminates the need for a dedicated COS hydrolysis device, maintaining a desulfurization rate of over 90% for gases with high COS content. Furthermore, it enables the catalytic hydrolysis and oxidation of COS dissolved in the liquid phase to elemental sulfur, achieving effective removal and recovery of sulfur from the high COS-content feed gas.

Description

Technical Field

[0001] This invention belongs to the field of gas purification, specifically relating to a process for producing elemental sulfur through COS absorption, hydrolysis, and oxidation. Technical Background

[0002] CO2 is a colorless, odorless, toxic, and flammable gas widely found in natural gas and blast furnace gas, a byproduct of the steel industry. CO2 molecules are physically and chemically stable, do not readily dissociate, and are difficult to liquefy, making them challenging to remove. While blast furnace gas is rich in valuable resources such as H2, CH4, and CO, the presence of CO2 not only causes pipeline corrosion and catalyst poisoning, but direct emissions can also lead to environmental problems like acid rain. Therefore, CO2 removal is crucial for meeting emission standards and improving the overall purification level of raw gas.

[0003] COs removal methods are mainly divided into dry and wet methods. Dry desulfurization has high precision and simple equipment, but sulfur-containing gases can easily poison the catalyst. Wet desulfurization has a larger sulfur capacity and better operational flexibility. It mainly uses absorption methods, including chemical absorption, physical absorption, and conversion absorption. Among them, conversion absorption combines COs absorption and hydrolysis, which is a new direction in COs removal research.

[0004] Currently, most industrial applications use aqueous solutions of alkanolamines as COS absorbents. This method initially employed single alkanolamine solutions such as ethanolamine, diethanolamine, and N-methyldiethanolamine as absorbents. However, to improve COS removal efficiency and address complex feed gas compositions, composite solvent formulations have gradually developed based on single alkanolamine absorption methods. For example, Chinese patent documents CN114250088A and CN111925848B add activators, defoamers, corrosion inhibitors, and other special solvents to alkanolamines to enhance COS removal. The COS-rich solution is regenerated through stripping and heating, but the hydrolysis generates a large amount of H₂S. - It remains in the lean solution. Patent CN112337295A adds dinuclear sulfonated cobalt phthalocyanine to an alkanolamine solution, and the dual catalytic action promotes the hydrolysis of COS to generate H2S. This is currently in the basic laboratory research stage. Patent CN111871193A removes acidic gases H2S and COS by mixing organic solvents, hydrolysis promoters, and sulfide ion converters in a microreactor, producing sulfur with a purity of 99.6%. Patent CN112473742A developed a triethanolamine-iron-based wet desulfurization catalyst, but its catalyst preparation process is complex. Formulated solvents can effectively achieve the absorption and hydrolysis conversion of COS, but existing production processes are complex, and the converted COS is still in the form of H2S. -The presence of COS in rich liquids and the instability of desulfurization products severely restrict its development in industrial production. With increasingly stringent environmental protection requirements, the scientific and resource-efficient utilization of high-sulfur energy has received widespread attention. COS accounts for 80-90% of organic sulfur content; therefore, a new and efficient COS removal process must be developed for deep removal of COS from coal gas. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides a process for producing elemental sulfur through COS absorption-hydrolysis-oxidation. By improving the composition and formulation of the COS removal solvent, a suitable production process is proposed. A composite solvent is used to first absorb and fix COS in the liquid phase, achieving a COS removal rate of over 90%. Then, through the alkaline action of amine compounds, COS is hydrolyzed and converted into H₂S. - Then, under the catalytic oxidation of oxidants 1,4-naphthoquinone or anthraquinone, HS... - The sulfur is oxidized to elemental sulfur, thus ensuring desulfurization while fully and effectively recovering and utilizing sulfur resources.

[0006] The present invention solves the above-mentioned technical problems by adopting the following technical solutions:

[0007] A process for producing elemental sulfur through COS absorption-hydrolysis-oxidation is as follows: 200-300 parts by weight of organic amine absorbent, 250-400 parts by weight of physical solvent, and 350-450 parts by weight of water are mixed in a storage tank and stirred evenly. Then, 0.016-0.032 parts by weight of oxidant are added and stirred until completely dissolved. Air is then introduced for activation for 3-5 hours to obtain a composite solvent. The activated composite solvent is pumped into the bubbling reactor from the bottom using a centrifugal pump at a certain flow rate. The gas to be treated, containing COS, is then introduced into the composite solvent through the gas inlet at the bottom of the bubbling reactor. The reaction is carried out using the bubbling absorption method for a period of time, and the purified gas, free of COS, is discharged from the gas outlet at the top of the bubbling reactor. The elemental sulfur generated in the reaction is discharged from the waste liquid outlet on the upper side wall of the bubbling reactor along with the reacted composite solvent. Elemental sulfur is then obtained by filtration and dehydration. The reacted composite solvent is regenerated by heating in a regenerator and then recycled with fresh composite solvent.

[0008] This invention utilizes physical solvents to fully dissolve COS in the liquid phase, and leverages the alkaline catalytic effect of amine solvents to hydrolyze COS into inorganic sulfur. An oxidant is then used to further oxidize the converted inorganic sulfur into elemental sulfur, thereby realizing the recovery and utilization of sulfur resources.

[0009] Preferably, the organic amine compound is one of diethylenetriamine and triethylenetetramine.

[0010] Preferably, the physical solvent is one of 1,4-dioxane and n-butanol.

[0011] Preferably, the oxidant is one of 1,4-naphthoquinone and anthraquinone.

[0012] Preferably, the pH of the composite solution is 9-10.

[0013] In one specific embodiment, the diethylenetriamine and triethylenetetramine molecules contain both primary and secondary amine groups, which can greatly increase the loading capacity and reaction rate of the absorbent, and is more conducive to the hydrolysis and conversion of COS.

[0014] In one specific embodiment, 1,4-dioxane and n-butanol are used as physical solvents, which can reduce the sensible heat and latent heat during solvent desorption and improve the desorption rate. 1,4-dioxane is an excellent aprotic solvent with high fluidity and good solubility, and can absorb COS polar gases.

[0015] In one specific embodiment, the 1,4-naphthoquinone and anthraquinone desulfurization catalysts have good catalytic oxidation performance, enabling the oxidation reaction to proceed rapidly under low-temperature conditions.

[0016] Preferably, in the COS absorption-hydrolysis-oxidation process for producing elemental sulfur according to the present invention, a constant temperature control system is provided outside the bubbling reactor, including a heat exchanger and an outer jacket; the elemental sulfur generated by the reaction is discharged from the waste liquid outlet on the upper side wall of the bubbling reactor along with the composite solvent after COS absorption; the composite solvent after filtration, dehydration and recovery of elemental sulfur is then regenerated by heating in a regenerator and then recycled into fresh composite solvent; during the reaction, the temperature inside the bubbling reactor is controlled at 35-60 ℃ by the constant temperature control system.

[0017] Preferably, in the COS absorption-hydrolysis-oxidation process for producing elemental sulfur according to the present invention, the bubble reactor is a 304 stainless steel bubble tower with a height-to-diameter ratio of 30-35:4-6. More preferably, the bubble reactor is provided with a wire mesh corrugated packing layer, and the outer wall of the tower is provided with a jacket. Even more preferably, the bottom of the bubble reactor is provided with a circular gas disperser, and the COS-containing gas to be treated enters the bubble reactor through the gas inlet and forms uniform bubbles through the circular gas disperser.

[0018] Preferably, in the COS absorption-hydrolysis-oxidation process for producing elemental sulfur according to the present invention, a batch reaction process is adopted, the COS gas concentration in the gas to be treated is 500-1000 ppm, and the COS gas to be treated is introduced into the bubbling reactor at a rate of 22-30 L / min.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0020] (1) In the COS absorption-hydrolysis-oxidation process for producing elemental sulfur described in this invention, the bubble reactor has an outer jacket for accurate temperature control, an inner wire mesh corrugated packing to ensure effective gas-liquid contact area, and a circular gas disperser at the bottom to uniformly disperse the gas entering the tower, thereby promoting gas-liquid mass transfer and accelerating the COS hydrolysis rate.

[0021] (2) In the COS absorption-hydrolysis-oxidation process for producing elemental sulfur described in this invention, a composite solvent is used to achieve COS absorption, hydrolysis and oxidation to produce elemental sulfur in one step. The desulfurization efficiency can reach more than 90%. It not only eliminates the need for a dedicated COS hydrolysis device, but also converts sulfides from gas to solid, promoting the forward reaction. The process is short and the equipment occupies a small area.

[0022] (3) The method of the present invention can be carried out under normal pressure, the reaction temperature is 35-60 ℃, the reaction conditions are mild, the organic amine desulfurization rich liquid after absorbing COS can be recycled after heating and regeneration, the COS desorption rate can reach 92%, the operation process is simple and the operating cost is low.

[0023] (4) The COS absorption-hydrolysis-oxidation process for producing elemental sulfur described in this invention still has a strong ability to remove sulfides under H2S gas conditions, with H2S and COS removal efficiencies reaching 99% and 90%, respectively. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the process flow for producing elemental sulfur using COS absorption-hydrolysis-oxidation according to a specific embodiment of the present invention.

[0025] Reference numerals: 1. Storage tank; 2. Gate valve; 3. Centrifugal pump; 4. Heat exchanger; 5. Corrugated wire mesh packing layer; 6. Bubbling reactor; 7. Filter; 8. Dryer; 9. Regenerator; 10. Gas disperser. Detailed Implementation

[0026] The following embodiments further describe the technical solutions of the present invention, but the scope of protection of the present invention is not limited to these embodiments.

[0027] like Figure 1 As shown, the process flow for producing elemental sulfur from COS absorption-hydrolysis-oxidation provided by this invention is as follows:

[0028] A certain weight proportions of amine solvent, physical solvent and water are added to storage tank 1 and mixed evenly. Then, an oxidant is added and air is introduced to activate the mixture for 3-6 hours to obtain a composite solvent.

[0029] Gate valve 2 and centrifugal pump 3 are opened, and the composite solvent is introduced into the bubbling reactor 6 from the bottom using centrifugal pump 3. Then, COS gas with a concentration of 500-1000 ppm is introduced into the composite solvent at a rate of 22-30 L / min through the gas inlet at the bottom of the bubbling reactor 6, and the reaction is carried out by bubbling absorption. Preferably, a gas disperser 10 is provided inside the bubbling reactor 6. After the COS-containing raw material gas enters the bubbling reactor 6 through the gas inlet, it is dispersed by the gas disperser 10 to form uniform bubbles. Preferably, a wire mesh corrugated packing layer 5 is provided inside the bubbling reactor 6, and the uniform bubbles absorb mass transfer after effective gas-liquid contact in the packing layer. During the reaction, the temperature inside the bubbling reactor is maintained at 35-60 ℃ by a constant temperature control system located outside the bubbling reactor 6. Preferably, the constant temperature control system is a heat exchanger 4.

[0030] After 3-5 hours of reaction, the purified gas with COS removed is discharged from the gas outlet at the top of the bubbling reactor 6. The purified gas with COS removed is collected, and the concentration of COS in the purified gas is measured by a gas chromatograph with a flame photometric detector. The COS removal efficiency is calculated using the formula K = (C0 - C) / C0 × 100%, where: K is the COS removal efficiency; C0 is the inlet COS concentration in ppm; and C is the outlet COS concentration in ppm.

[0031] The suspended elemental sulfur generated in the reaction is discharged from the waste liquid outlet on the upper side wall of the bubbling reactor 6 along with the composite solvent after the reaction; then it is filtered by filter 7 and dried by dryer 8 to obtain elemental sulfur. The composite solvent after recovering the elemental sulfur is then heated and regenerated by regenerator 9 located outside the bubbling tower 6, and the regenerated composite solvent is incorporated into the fresh composite solvent for recycling.

[0032] The process for producing elemental sulfur through COS absorption-hydrolysis-oxidation according to the present invention includes the following steps in the preparation method of the composite solvent:

[0033] (1) Weigh out 200-300 parts by weight of organic amine compound, 250-400 parts by weight of physical solvent, 350-450 parts by weight of water, and 0.016-0.032 parts by weight of oxidant into a stirring tank and stir to mix evenly; the organic amine compound is preferably one of diethylenetriamine and triethylenetetramine; the physical solvent is preferably one of 1,4-dioxane and n-butanol; the oxidant is preferably one of 1,4-naphthoquinone and anthraquinone;

[0034] (2) Weigh the above-mentioned oxidant and add it to the solution obtained in step (1). Stir, dissolve, and activate with air for 3-5 hours to obtain a composite solvent with a pH of 9-10.

[0035] In the COS absorption-hydrolysis-oxidation process for producing elemental sulfur described in this invention, COS gas detection is performed using a gas chromatograph with a flame photometric detector. A 100 mL glass syringe is used to take a sample every 20 minutes to determine the outlet COS concentration and calculate the COS removal rate.

[0036] The formula for calculating COS removal efficiency is as follows:

[0037] K = (C0 - C) / C0 × 100%,

[0038] In the formula: K is the COS removal efficiency; C0 is the inlet COS concentration in ppm; C is the outlet COS concentration in ppm.

[0039] The principle of the COS absorption-hydrolysis-oxidation process for producing elemental sulfur provided by this invention is as follows: COS gas is uniformly dispersed at the bottom of the reactor through the micropores of a gas-liquid distributor. As COS molecules in the gas rise from the bottom of the reactor through the liquid bulk, the physical solvent promotes the rapid diffusion of COS into the liquid phase. Then, the alkaline action of the amine solvent catalyzes the hydrolysis to produce CO2 and H2S. The H2S is then absorbed again to generate HS. - The catalytic oxidation properties of 1,4-naphthoquinone promote the formation of HS - It is converted into suspended elemental sulfur.

[0040]

[0041]

Example 1

[0042] In this embodiment, the following raw materials in parts by weight: 250 parts diethylenetriamine, 300 parts 1,4-dioxane, 400 parts water, and 0.024 parts 1,4-naphthoquinone were stirred and dissolved in a storage tank, and then activated by air for 3 hours to obtain a composite solvent.

[0043] In this embodiment, the height-to-diameter ratio of the bubbling reactor is set to 30:6, and the reactor temperature is controlled at 40 ℃. A gas to be treated with a COS concentration of 510 ppm is introduced at a flow rate of 26 L / min. The gas is dispersed into uniform bubbles by a gas-liquid distributor and passes through the composite solvent, ensuring full contact with the solvent in the wire mesh corrugated packing layer. The reaction continues for 3 hours.

[0044] COS gas passing through the composite solvent was sampled every 20 minutes using a 100 mL glass syringe. The concentration of COS in the purified gas was measured to be 66 ppm by a gas chromatograph with a flame photometric detector. Therefore, under the conditions of this embodiment, the COS removal efficiency of the composite solvent is 87%.

[0045]

Example 2

[0046] In this embodiment, the following raw materials in parts by weight: 250 parts diethylenetriamine, 300 parts 1,4-dioxane, 400 parts water, and 0.024 parts 1,4-naphthoquinone were stirred and dissolved in a storage tank, and then activated by air for 3 hours to obtain a composite solvent.

[0047] In this embodiment, the height-to-diameter ratio of the bubbling reactor is set to 35:4, and the reactor temperature is controlled at 40 ℃. A gas to be treated with a COS concentration of 510 ppm is introduced at a flow rate of 26 L / min. The gas is dispersed into uniform bubbles by a gas-liquid distributor and passes through the composite solvent, ensuring full contact with the solvent in the wire mesh corrugated packing layer. The reaction continues for 4 hours.

[0048] COS gas passing through the composite solvent was sampled every 20 minutes using a 100 mL glass syringe. The concentration of COS in the purified gas was measured to be 50 ppm using a gas chromatograph with a flame photometric detector. Therefore, under the conditions of this embodiment, the COS removal efficiency of the composite solvent is 90%.

[0049]

Example 3

[0050] In this embodiment, the following raw materials in parts by weight: 250 parts diethylenetriamine, 300 parts 1,4-dioxane, 400 parts water, and 0.024 parts 1,4-naphthoquinone were stirred and dissolved in a storage tank, and then activated by air for 4 hours to obtain a composite solvent.

[0051] In this embodiment, the height-to-diameter ratio of the bubbling reactor is set to 35:4, and the reactor temperature is controlled at 60 ℃. A gas to be treated with a COS concentration of 1000 ppm is introduced at a flow rate of 26 L / min. The gas is dispersed into uniform bubbles by a gas-liquid distributor and passes through the composite solvent, ensuring full contact with the solvent in the wire mesh corrugated packing layer. The reaction continues for 3 hours.

[0052] COS gas passing through the composite solvent was sampled every 20 minutes using a 100 mL glass syringe. The concentration of COS in the purified gas was measured to be 37 ppm by a gas chromatograph with a flame photometric detector. Therefore, under the conditions of this embodiment, the COS removal efficiency of the composite solvent is 96%.

[0053]

Example 4

[0054] In this embodiment, the following raw materials in parts by weight: 250 parts diethylenetriamine, 300 parts 1,4-dioxane, 400 parts water, and 0.024 parts 1,4-naphthoquinone were stirred and dissolved in a storage tank, and then activated by air for 4 hours to obtain a composite solvent.

[0055] In this embodiment, the height-to-diameter ratio of the bubbling reactor is set to 35:4, and the reactor temperature is controlled at 60 ℃. A gas to be treated with a COS concentration of 1000 ppm is introduced at a flow rate of 30 L / min. The gas is dispersed into uniform bubbles by a gas-liquid distributor and passes through the composite solvent, ensuring full contact with the solvent in the wire mesh corrugated packing layer. The reaction continues for 4 hours.

[0056] COS gas passing through the composite solvent was sampled every 20 minutes using a 100 mL glass syringe. The concentration of COS in the purified gas was measured to be 97 ppm by a gas chromatograph with a flame photometric detector. Therefore, under the conditions of this embodiment, the COS removal efficiency of the composite solvent is 92%.

[0057]

Example 5

[0058] In this embodiment, the following raw materials in parts by weight: 300 parts triethylenetetramine, 300 parts 1,4-dioxane, 400 parts water, and 0.024 parts 1,4-naphthoquinone were stirred and dissolved in a storage tank, and then activated by air for 4 hours to obtain a composite solvent.

[0059] In this embodiment, the height-to-diameter ratio of the bubbling reactor is set to 35:4, and the reactor temperature is controlled at 60 ℃. A gas to be treated with a COS concentration of 1000 ppm is introduced at a flow rate of 30 L / min. The gas is dispersed into uniform bubbles by a gas-liquid distributor and passes through the composite solvent, ensuring full contact with the solvent in the wire mesh corrugated packing layer. The reaction continues for 3 hours.

[0060] COS gas passing through the composite solvent was sampled every 20 minutes using a 100 mL glass syringe. The concentration of COS in the purified gas was measured to be 25 ppm by a gas chromatograph flame photometric detector. Therefore, under the conditions of this embodiment, the COS removal efficiency of the composite solvent is 97%.

[0061]

Example 6

[0062] In this embodiment, the following raw materials in parts by weight: 250 parts triethylenetetramine, 400 parts n-butanol, 350 parts water, and 0.024 parts 1,4-naphthoquinone were stirred and dissolved in a storage tank, and then activated by air for 4 hours to obtain a composite solvent.

[0063] In this embodiment, the height-to-diameter ratio of the bubbling reactor is set to 35:4, and the reactor temperature is controlled at 60 ℃. A gas to be treated with a COS concentration of 1000 ppm is introduced at a flow rate of 30 L / min. The gas is dispersed into uniform bubbles by a gas-liquid distributor and passes through the composite solvent, ensuring full contact with the solvent in the wire mesh corrugated packing layer. The reaction continues for 3 hours.

[0064] COS gas passing through the composite solvent was sampled every 20 minutes using a 100 mL glass syringe. The concentration of COS in the purified gas was measured to be 31 ppm by a gas chromatograph with a flame photometric detector. Therefore, under the conditions of this embodiment, the COS removal efficiency of the composite solvent is 94%.

[0065]

Example 7

[0066] In this embodiment, the following raw materials in parts by weight: 250 parts triethylenetetramine, 400 parts n-butanol, 350 parts water, and 0.032 parts anthraquinone were stirred and dissolved in a storage tank, and then activated by air for 4 hours to obtain a composite solvent.

[0067] In this embodiment, the height-to-diameter ratio of the bubbling reactor is set to 35:4, and the reactor temperature is controlled at 60 ℃. A gas to be treated with a COS concentration of 1000 ppm is introduced at a flow rate of 30 L / min. The gas is dispersed into uniform bubbles by a gas-liquid distributor and passes through the composite solvent, ensuring full contact with the solvent in the wire mesh corrugated packing layer. The reaction continues for 4 hours.

[0068] COS gas passing through the composite solvent was sampled every 20 minutes using a 100 mL glass syringe. The concentration of COS in the purified gas was measured to be 48 ppm by a gas chromatograph with a flame photometric detector. Therefore, under the conditions of this embodiment, the COS removal efficiency of the composite solvent is 95%.

[0069]

Example 8

[0070] In this embodiment, the following raw materials in parts by weight: 300 parts triethylenetetramine, 300 parts n-butanol, 400 parts water, and 0.024 parts anthraquinone were stirred and dissolved in a storage tank, and then activated by air for 4 hours to obtain a composite solvent.

[0071] In this embodiment, the height-to-diameter ratio of the bubbling reactor is set to 35:4, and the reactor temperature is controlled at 60 ℃. A gas to be treated, containing 6000 ppm H2S and 1000 ppm COS, is introduced at a flow rate of 22 L / min. The gas is dispersed into uniform bubbles by a gas-liquid distributor and passes through the composite solvent, ensuring full contact with the solvent in the wire mesh corrugated packing layer. The reaction continues for 4 hours.

[0072] COS gas passing through the composite solvent was sampled every 20 minutes using a 100 mL glass syringe. The concentrations of H2S and COS in the purified gas were measured to be 15 ppm and 68 ppm, respectively, by a gas chromatograph with a flame photometric detector. Therefore, under the conditions of this embodiment, the removal efficiency of COS by the composite solvent is 99% and 93%.

[0073] Comparative Example 1

[0074] In this embodiment, the following raw materials in parts by weight: 300 parts of 1,4-dioxane, 400 parts of water, and 0.024 parts of 1,4-naphthoquinone were stirred and dissolved in a storage tank, and then activated by air for 4 hours to obtain a composite solvent.

[0075] In this embodiment, the height-to-diameter ratio of the bubbling reactor is set to 35:4, and the reactor temperature is controlled at 60 ℃. A feed gas containing 1000 ppm COS is introduced at a flow rate of 26 L / min. The gas is dispersed into uniform bubbles by a gas-liquid distributor, passes through the composite solvent, and fully contacts the solvent in the wire mesh corrugated packing layer. The reaction continues for 3 hours.

[0076] COS gas passing through the composite solvent was sampled every 20 minutes using a 100 mL glass syringe. The concentration of COS in the purified gas was measured to be 613 ppm by a gas chromatograph with a flame photometric detector. Therefore, under the conditions of this embodiment, the COS removal efficiency of the composite solvent is 39%.

[0077] Comparative Example 2

[0078] In this embodiment, the following raw materials in parts by weight: 250 parts diethylenetriamine, 400 parts water, and 0.024 parts 1,4-naphthoquinone were stirred and dissolved in a storage tank, and then activated by air for 4 hours to obtain a composite solvent.

[0079] In this embodiment, the height-to-diameter ratio of the bubbling reactor is set to 35:4, and the reactor temperature is controlled at 60 ℃. A feed gas containing 1000 ppm COS is introduced at a flow rate of 26 L / min. The gas is dispersed into uniform bubbles by a gas-liquid distributor, passes through the composite solvent, and fully contacts the solvent in the wire mesh corrugated packing layer. The reaction continues for 3 hours.

[0080] COS gas passing through the composite solvent was sampled every 20 minutes using a 100 mL glass syringe. The concentration of COS in the purified gas was measured to be 177 ppm by a gas chromatograph with a flame photometric detector. Therefore, under the conditions of this embodiment, the COS removal efficiency of the composite solvent is 82%.

[0081] Comparative Example 3

[0082] In this embodiment, the following raw materials in parts by weight: 250 parts diethylenetriamine, 300 parts 1,4-dioxane, and 400 parts water were stirred and dissolved in a storage tank, and then activated by air for 4 hours to obtain a composite solvent.

[0083] In this embodiment, the height-to-diameter ratio of the bubbling reactor is set to 35:4, and the reactor temperature is controlled at 60 ℃. A feed gas containing 1000 ppm COS is introduced at a flow rate of 26 L / min. The gas is dispersed into uniform bubbles by a gas-liquid distributor, passes through the composite solvent, and fully contacts the solvent in the wire mesh corrugated packing layer. The reaction continues for 3 hours.

[0084] COS gas passing through the composite solvent was sampled every 20 minutes using a 100 mL glass syringe. The concentration of COS in the purified gas was measured to be 114 ppm by a gas chromatograph with a flame photometric detector. Therefore, under the conditions of this embodiment, the COS removal efficiency of the composite solvent is 88%.

[0085] By comparing the COS removal efficiency in Examples 1 and 2, it was found that increasing the height-to-diameter ratio of the bubbling reactor from 30:6 to 35:4, and increasing the number of theoretical plates, increased the COS removal efficiency by 3%. However, compared to Example 3, increasing the temperature of the bubbling reactor, even for a COS concentration doubled, resulted in a 6% increase in COS removal efficiency of the composite solvent compared to Example 2. In Example 4, compared to Example 3, increasing the COS gas velocity from 26 L / min to 30 L / min resulted in a 4% decrease in COS removal efficiency. Therefore, the process condition with the greatest impact on desulfurization efficiency is temperature, followed by the height-to-diameter ratio and gas flow rate.

[0086] By comparing the COS removal efficiency in Examples 4 with Examples 5, 6, and 7, it was found that the content of organic amines had the greatest impact on desulfurization efficiency, followed by the content of physical solvents, while the content of oxidant had the least impact. Comparing the COS removal efficiency in Example 4 with Comparative Examples 1, 2, and 3 revealed results consistent with the above findings. The influence of the organic amine solvent, physical solvent, and oxidant on the COS desulfurization efficiency gradually decreases, but all three have a synergistic effect and are indispensable. The physical solvent allows COS to quickly reach the bulk liquid and undergo hydrolysis with the alkaline organic amine compounds, generating HS... - Under the action of the oxidant, elemental sulfur is generated. The continuous removal of elemental sulfur from the system is conducive to the positive progress of the overall COS absorption-hydrolysis-oxidation reaction, thereby ensuring the stable and efficient operation of the COS absorption-hydrolysis-oxidation process for producing elemental sulfur.

[0087] The foregoing has described in detail the preferred embodiments of the present invention. It can be seen that the results of the present invention can be modified and altered in many ways without creative effort based on the design content of the present invention. Therefore, all technical solutions obtained by those skilled in the art through reasoning or experimentation based on the technical foundation of the present invention are within the scope of protection of the claims of the present invention.

Claims

1. A process for producing elemental sulfur through COS absorption-hydrolysis-oxidation, characterized in that... : Mix 200-300 parts by weight of organic amine absorbent, 250-400 parts by weight of physical solvent and 350-450 parts by weight of water in a storage tank (1), stir evenly, then add 0.016-0.032 parts by weight of oxidant, stir until completely dissolved, and then activate with air for 3-5 h to obtain a composite solvent; The composite solvent is fed into the bubbling reactor (6) using a centrifugal pump (3), and then the gas to be treated containing COS is passed into the composite solvent. The reaction is carried out by bubbling absorption for a period of time. The purified gas after removing COS is discharged from the gas outlet at the top of the bubbling reactor (6). The suspended sulfur generated by the reaction is discharged from the waste liquid outlet at the top of the bubbling reactor (6) along with the composite solvent after the reaction. Then, elemental sulfur is obtained by filtration and drying. The composite solvent after the reaction is regenerated by heating in a regenerator (9) and then recycled into fresh composite solvent; In the composite solvent, the organic amine absorbent is one of diethylenetriamine and triethylenetetramine; the physical solvent is one of 1,4-dioxane and n-butanol; the oxidant is one of 1,4-naphthoquinone and anthraquinone; and the pH of the composite solvent is 9-10.

2. The process for producing elemental sulfur by COS absorption-hydrolysis-oxidation according to claim 1, characterized in that: The bubbling reactor (6) is equipped with a heat exchanger (4), an outer wall jacket, and a constant temperature control system. During the reaction, the temperature inside the bubbling reactor is controlled to be 35-60 ℃ by the constant temperature control system.

3. The process for producing elemental sulfur by COS absorption-hydrolysis-oxidation according to claim 1, characterized in that: The bubble reactor (6) is made of 304 stainless steel and has a height-to-diameter ratio of (30-35):(4-6).

4. The process for producing elemental sulfur by COS absorption-hydrolysis-oxidation according to claim 1, characterized in that: The bubble reactor (6) is provided with a wire mesh corrugated packing layer (5).

5. The process for producing elemental sulfur by COS absorption-hydrolysis-oxidation according to claim 1, characterized in that: The bubble reactor is equipped with a circular gas disperser (10). The gas to be treated containing COS enters the bubble reactor through the gas inlet and forms uniform bubbles through the circular gas disperser (10).

6. The process for producing elemental sulfur by COS absorption-hydrolysis-oxidation according to any one of claims 1 to 5, characterized in that: A batch reaction process is adopted, with a COS concentration of 500-1000 ppm in the gas to be treated containing COS. The gas to be treated containing COS is introduced into the bubbling reactor (6) at a rate of 22-30 L / min, and the reaction time is 3-6 h.

7. A composite solvent, characterized in that... The composite solvent is prepared by mixing 200-300 parts by weight of organic amine absorbent, 250-400 parts by weight of physical solvent and 350-450 parts by weight of water in a storage tank (1), stirring until uniform, adding 0.016-0.032 parts by weight of oxidant, stirring until completely dissolved, and then activating with air for 3-5 hours. The organic amine absorbent is one of diethylenetriamine and triethylenetetramine; the physical solvent is one of 1,4-dioxane and n-butanol; the oxidant is one of 1,4-naphthoquinone and anthraquinone; and the pH of the composite solvent is 9-10.

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