A resource utilization method of HPF wet desulfurization by-product sulfur paste

Abstract

The present application relates to a kind of HPF wet desulfurization by-product sulphur paste resource utilization method.The method is converted into high value-added fine chemicals taurine by the by-product sulphur paste of HPF wet desulfurization through superoxidation, substitution / imidization / oxidation and reduction step.The method solves the problem of by-product sulphur paste in the HPF wet desulfurization process of coking enterprise, compared with the existing treatment scheme of sulphur production by melting sulphur, the value of sulphur paste is greatly improved in the present application, high value taurine product widely used in medicine, food processing, feed and other industries is prepared, and ammonium chloride is produced, and the resource utilization of sulphur paste is realized.

Description

Technical Field

[0001] This invention relates to the field of fine chemicals, specifically to a method for preparing taurine, a high-value-added fine chemical, using sulfur paste, a byproduct of HPF wet desulfurization in coking plants. Background Technology

[0002] HPF (High-Performance Fluidization) desulfurization and decyanation technology is a widely adopted wet gas desulfurization technology in domestic coking enterprises. In this technology, after absorbing hydrogen sulfide from raw coal gas in the desulfurization section, the resulting rich desulfurization liquid undergoes a regeneration process. The absorbed sulfide is then oxidized to elemental sulfur, which is suspended in the desulfurization liquid as sulfur foam. Solid-liquid separation yields sulfur paste with a water content of approximately 40%. Sulfur paste is a complex mixture, yellowish-green in appearance, composed of sulfur particles, a small amount of tar, ammonium thiocyanate, ammonium thiosulfate, ammonium sulfite, and ammonium sulfate. It is highly toxic, has a strong odor, is highly corrosive, poses a significant environmental hazard, and is very difficult to store and transport. It is usually transported and disposed of by qualified companies at low prices, sometimes even at a loss. For example, a common method is to dehydrate, melt, shape, and cool the sulfur paste into sulfur blocks, which are then sold to sulfuric acid plants for sulfuric acid production. However, this method has very low added value. In summary, the sulfur paste produced by the HPF desulfurization and decyanation process not only has low added value and is difficult to handle, but also brings greater environmental risks and operational cost pressures to coking enterprises.

[0003] Therefore, it is still necessary to develop a resource utilization method for sulfur paste, a by-product of coking plants, to produce high-value-added products. Summary of the Invention

[0004] To address the shortcomings of sulfur paste, such as significant environmental pollution, limited application scenarios, and low added value, this invention proposes a resource utilization method for producing taurine, a key pharmaceutical and feed product, from sulfur paste, a byproduct of coking plants, and simultaneously generating ammonium chloride fertilizer. In this invention, the taurine product has stable quality, almost no waste salt emissions, and low production costs, effectively improving the treatment level of sulfur paste and increasing its added value.

[0005] To address the above problems, this invention provides a method for the resource utilization of sulfur paste, a byproduct of HPF wet desulfurization.

[0006] As shown in the following reaction equation:

[0007]

[0008] The method includes the following steps:

[0009] 1) Oversulfurization section: The sulfur paste produced by HPF wet desulfurization is quantitatively analyzed to determine the accurate sulfur content. Then, a quantitative amount of ammonium sulfide aqueous solution and sulfur paste are mixed in proportion to obtain an ammonium sulfide I solution. After separation, the tar contained in the sulfur paste is removed by layering.

[0010] 2) Substitution / Imine / Oxidation Section: Chloroacetaldehyde and ammonium persulfate I obtained in step 1) are mixed and subjected to a substitution reaction at a temperature of 30-90°C. After the reaction is completed, an aqueous solution containing the intermediate dithiodiacetaldehyde is obtained. Subsequently, the pH value is adjusted to acidic. Under the condition that imine is fully generated by imine reaction, nitroethylsulfonic acid derivative II is obtained by oxidation reaction under the action of catalyst 1 and hydrogen peroxide.

[0011] 3) Reduction section: Under the action of catalyst 2 and hydrogen, the nitroethylsulfonic acid derivative II obtained in the previous step is reduced to crude taurine.

[0012] Optionally, the method further includes:

[0013] 4) Refining section: Taurine crude product is crystallized to obtain taurine. Most of the water is distilled off and reused in the HPF wet desulfurization section. The residual bottom liquid contains ammonium chloride crude product, which can be recycled to step 2) or sold directly.

[0014] In a specific embodiment, in step 1), the sulfur content in the sulfur paste is 40–80 wt%, typically 60 wt%. The remaining portion of the sulfur paste is mainly saline wastewater, containing salts such as ammonium sulfide, ammonium hydrosulfide, and ammonium thiocyanate, with a content of 1–5 wt%, typically 1–2 wt%. The organic matter in the sulfur paste is mainly tar suspended in the paste, mixed with sulfur particles and difficult to separate. Therefore, the sulfur paste is directly mixed with an ammonium sulfide solution to prepare superammonium sulfide.

[0015] In a specific embodiment, in step 1), a commercially available 20–26 wt% ammonium sulfide solution is used. The accurate content of ammonium sulfide is determined by precipitation, and the amount of sulfur paste added is calculated based on the mass of sulfur contained therein. That is, the molar ratio of ammonium sulfide to sulfur is 1:1 to 1.2, preferably 1:1.01.

[0016] In a specific embodiment, in step 1), 100g of 24wt% ammonium sulfide solution is added, and correspondingly, 19g of sulfur paste with a sulfur content of 60wt% is added.

[0017] In a specific embodiment, in step 1), the reaction temperature is 20–90°C, preferably 50–55°C; the reaction time is 1–24 hours, preferably 4–6 hours.

[0018] In a specific implementation, after the reaction is completed in step 1), the reaction liquid is transferred to a phase separation tank to stand and cool to room temperature. The lower aqueous phase is then transferred to the next reaction vessel for step 2). The small amount of organic matter (tar) on the upper layer of the phase separation tank is released after multiple accumulations and can be combined with the coal tar produced by the coking plant.

[0019] In a specific embodiment, in step 2), the molar ratio of chloroacetaldehyde (100% concentration) to the ammonium persulfate generated in step 1) is 2–5:1, preferably 2.02:1. The reaction temperature is 30–90°C, preferably 40–70°C; the reaction time is 0.5–24 hours, preferably 2–3 hours.

[0020] In a specific embodiment, in step 2), the end of the reaction is indicated by the complete fading of the color of the aqueous phase in the reaction system. The reaction solution is used directly in step 3) without further treatment. Chloroacetaldehyde is a commercially available product, preferably a 40 wt% aqueous solution.

[0021] In a specific embodiment, in step 2), the pH of the reaction solution is adjusted to 1-5, preferably 4-5, and the reaction is carried out for 1-24 hours, preferably 4-6 hours; then, hydrogen peroxide and catalyst 1 are added, and the reaction is continued for a period of time. After that, catalyst 1 is removed by filtration, and the resulting reaction solution is used directly in step 3 without further processing.

[0022] In a specific embodiment, in step 2), the molar ratio of hydrogen peroxide (100% concentration) to chloroacetaldehyde (100% concentration) is 6–20:1, preferably 14–16:1. The hydrogen peroxide is a commercially available product with a content of 30–70%, preferably 30% or 50%. Catalyst 1 is an acidic molecular sieve catalyst or a solid acid catalyst, such as ZSM-5, TS-1, macroporous acidic resin, phosphotungstic acid, phosphomolybdic acid, etc. Preferably, TS-1 is used as the catalyst, and its addition amount is 1–5% of the mass of the reaction solution, preferably 2–3%. The reaction temperature is 30–100°C, preferably 80°C; the reaction time is 1–24 hours, preferably 3–5 hours. After the reaction is completed, the catalyst 1 can be reused after filtration.

[0023] In a specific embodiment, in step 3), catalyst 2 is added to the reaction solution obtained in step 2), and then hydrogen gas is introduced to carry out a reduction reaction, resulting in a solution containing taurine product.

[0024] In a specific embodiment, in step 3), catalyst 2 can be Raney-Ni, Rh / C, Rh / Al, Pd / C, etc., preferably 5% or 10% Pd / C, and the amount added is 1-10% of the mass of the reaction solution, preferably 2-3%. The hydrogen pressure is 0.1-10 MPa, preferably 1-2 MPa. The reaction time is 1-4 hours, preferably 2-3 hours. The reaction temperature is 20-100℃, preferably 60-65℃.

[0025] In a specific implementation, in step 4), the mother liquor after taurine crystallization can be recycled. After multiple recycling cycles, the accumulated ammonium chloride content can rise to 10 wt%, potentially affecting the quality of the taurine product. At this point, the mother liquor can be drawn out and completely concentrated. The crystallized crude taurine is returned to the crystallization process, the distilled water is returned to the HPF wet desulfurization section, and the remaining ammonium chloride can be returned to step 2) for recycling or sold externally.

[0026] Beneficial effects

[0027] This invention designs a novel method for the resource utilization of sulfur paste, which has the following advantages:

[0028] 1. Solved the problem of handling by-product sulfur paste in the HPF wet desulfurization process that has plagued coking enterprises;

[0029] 2. Compared with the existing sulfur production process using the molten sulfur method, this invention significantly increases the value of sulfur paste, producing high-value taurine products that are widely used in the pharmaceutical, food processing, and feed industries. At the same time, ammonium chloride is produced as a byproduct, realizing the resource utilization of sulfur paste.

[0030] 3. By adopting this invention, a closed-loop process for sulfur paste in coking plants is achieved, with no waste salt or wastewater generated throughout the entire process.

[0031] 4. In the comparative examples, the comparative experiment using elemental sulfur as raw material showed that there was no significant difference in quality between the taurine produced by this process and the taurine produced by this process.

[0032] The present invention has been described in detail above; however, the above embodiments are merely illustrative in nature and are not intended to limit the invention. Furthermore, this document is not limited to the foregoing prior art or the invention itself, or to any theory described in the following embodiments. Attached Figure Description

[0033] Figure 1 The process flow diagram of this application.

[0034] Figure 2 The effect of reaction temperature on the reaction between ammonium persulfate and chloroacetaldehyde is shown in the curve.

[0035] Figure 3 The appearance of the product prepared by the method of this application is as follows: the product in the upper bag is a product of primary crystallization, and the product in the lower bag is a product of secondary crystallization. Detailed Implementation

[0036] The present invention will be further described below with reference to embodiments. It should be noted that the following embodiments are provided for illustrative purposes only and do not constitute a limitation on the scope of protection of the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0037] Unless otherwise specified, the raw materials, reagents, and methods used in the examples are all conventional in the art and are commercially available unless otherwise specified.

[0038] The process is specifically described in the following embodiments:

[0039] Example 1: Process for preparing taurine using sulfur paste

[0040] Materials: 60wt% sulfur paste, elemental sulfur and hydrogen were produced by Hebei Xuyang New Energy; 50wt% hydrogen peroxide came from Cangzhou Xuyang Chemical Company; 24wt% ammonium sulfide and 40wt% chloroacetaldehyde were sourced from Aladdin or Maclean Reagent Company; TS-1 catalyst was purchased from Zhuoyue Environmental New Materials Company; and 5% Pd / C catalyst was sourced from Xi'an Kaili Catalyst Company.

[0041] Step 1: In a 500mL round-bottom flask, add 19g of sulfur paste and 100g of ammonium sulfide solution sequentially. Under nitrogen protection, react at 55℃ for 6 hours. After the reaction is complete, cool the reaction solution to room temperature, then transfer it to a separatory funnel and let it stand for 1 hour to separate the lower aqueous layer (dark red liquid), which can be used directly for the second step of the reaction.

[0042] Step 2: At room temperature, 56g of chloroacetaldehyde solution was added sequentially to a 500mL round-bottom flask. The reaction solution from Step 1 was reacted at 45°C for 3 hours under nitrogen protection. After the reaction, the system appeared pale yellow-green and slightly turbid. Without purification or post-treatment, the pH of the reaction solution was adjusted by adding a small amount of 10% hydrochloric acid solution to adjust the pH to 4, and the reaction was continued at room temperature for 6 hours. The reaction solution was then transferred to a 1000mL three-necked round-bottom flask and cooled to 0-5°C in an ice bath. 4.5g of catalyst TS-1 was added, followed by 360g of 50% hydrogen peroxide slowly added dropwise through a constant-pressure dropping funnel over approximately 1 hour. During the addition, the temperature of the reaction system was carefully controlled to not exceed 5°C. After the addition was complete, the system was heated to 80°C and the reaction continued for 3-4 hours. After the reaction, the TS-1 catalyst was filtered off while hot and reused. The filtrate was cooled to room temperature.

[0043] Third, the reaction solution from the second step was transferred to a 1000 mL high-pressure reactor, 13.3 g of 5% Pd / C was added, the reactor was sealed, nitrogen was purged three times, hydrogen was introduced to maintain the reaction pressure at 2.0 MPa, the temperature was raised to 60 °C, and the reaction was carried out for 3 hours. After the reaction was completed, nitrogen was purged, the pressure was released, the reaction solution was cooled to room temperature, the catalyst was removed by filtration, and the taurine content in the reaction solution was detected by LC chromatography to calculate the reaction yield.

[0044] The fourth step involves concentrating the reaction solution from the fourth step using vacuum distillation. The concentrated water is either used in the reaction or returned to the HPF wet desulfurization process. The concentrated solution is cooled and crystallized to precipitate taurine. After filtration or centrifugation, the taurine product is obtained, and the remaining mother liquor is recycled. After multiple recycling cycles, the cumulative ammonium chloride content of the mother liquor can rise to approximately 10 wt%, which may affect the quality of the taurine product. The solution is to draw out the mother liquor from multiple cycles and concentrate it completely. The crystallized crude taurine is returned to the crystallization process, while the distilled water is returned to the HPF wet desulfurization process. The remaining ammonium chloride can be returned to the second step for recycling or sold externally. Specific data are shown in Table 1. A schematic flowchart of the above steps can be found in [reference needed]. Figure 1 .

[0045] Example 2: Application of Catalyst 1 and Catalyst 2

[0046] The operation method is the same as in Example 1, wherein catalyst 1 and catalyst 2 are both recycled catalysts, recycled 6 times, and the specific data are shown in Table 1.

[0047] Example 3 Effect of reaction temperature on the yield of dithiodiacetaldehyde

[0048] The preparation method of ammonium persulfate is the same as the first step in Example 1. In a 500 mL round-bottom flask, 56 g of chloroacetaldehyde solution was added sequentially. The reaction solution from the first step was reacted under nitrogen protection at different temperature points selected within the range of 20–90 °C, with a reaction time of 3 hours for each temperature. After the reaction, the content of dithiodiacetaldehyde was analyzed by LC. The effect of reaction temperature on the yield of dithiodiacetaldehyde is shown in [reference needed]. Figure 2 .

[0049] from Figure 2 The results shown indicate that the reaction product content is high when the reaction temperature is in the range of 40-70℃.

[0050] Comparative Example: Taurine Prepared Using Elemental Sulfur as a Raw Material

[0051] The starting materials were 100g of 24wt% ammonium sulfide solution, 11.4g of elemental sulfur and 8.6g of deionized water. Other raw materials and operating methods were the same as in Example 1. Specific data are shown in Table 1.

[0052] Table 1

[0053]

[0054]

[0055] As can be seen from the data in Table 1 above, the taurine produced by this process is not significantly different in quality from the comparative example that uses elemental sulfur as raw material.

[0056] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for the resource utilization of sulfur paste, a byproduct of HPF wet desulfurization. As shown in the following reaction equation: The method includes the following steps: 1) Oversulfurization section: The sulfur paste produced by HPF wet desulfurization is quantitatively analyzed to determine the accurate sulfur content. Then, a quantitative amount of ammonium sulfide aqueous solution and sulfur paste are mixed at a molar ratio of 1:1 to 1.2 to obtain an ammonium sulfide I solution. After separation, the tar contained in the sulfur paste is removed by layering. 2) Substitution / Imine / Oxidation Section: Chloroacetaldehyde and ammonium persulfate I obtained in step 1) are mixed at a molar ratio of 2 to 5:1 under heating to 30 to 90 °C to carry out a substitution reaction. After the reaction is completed, an aqueous solution containing the intermediate dithiodiacetaldehyde is obtained. Subsequently, the pH value is adjusted to 1 to 5. Under the condition that the imine reaction has fully generated imine, and in the presence of catalyst 1 and hydrogen peroxide, and under the condition that the molar ratio of hydrogen peroxide to chloroacetaldehyde is 14 to 16:1, nitroethylsulfonic acid derivative II is obtained by oxidation reaction. The catalyst 1 is TS-1. 3) Reduction section: Under the action of catalyst 2 and hydrogen, the nitroethylsulfonic acid derivative II obtained in the previous step is reduced to crude taurine. The catalyst 2 is Raney-Ni, Rh / C, Rh / Al or Pd / C, and the hydrogen pressure is 0.1 ~ 10 MPa. Optionally, the method further includes: 4) Refining section: Taurine crude product is crystallized to obtain taurine. The distilled water is reused in the HPF wet desulfurization section. The residual bottom liquid contains ammonium chloride crude product which is recycled to step 2, or sold directly.

2. The method according to claim 1, wherein, In step 1), the sulfur content in the sulfur paste is 40-80 wt%.

3. The method according to claim 1, wherein, In step 1), ammonium sulfide is used in a 20–26 wt% ammonium sulfide solution, and the molar ratio of ammonium sulfide to sulfur is 1:1.01; and / or In step 1), the reaction temperature is 20 ~ 90 ℃; the reaction time is 1 ~ 24 hours.

4. The method according to claim 3, wherein, In step 1), the reaction temperature is 50-55°C; the reaction time is 4-6 hours.

5. The method according to claim 1, wherein, In step 1), after the reaction is completed, the reaction liquid is transferred to a phase separation tank to stand and cool to room temperature. The lower aqueous phase is transferred to the next reaction vessel for operation 2). The small amount of organic tar in the upper layer of the phase separation tank is released after multiple accumulations and combined with the coal tar produced by the coking plant.

6. The method according to claim 1, wherein, In step 2), the molar ratio of chloroacetaldehyde to ammonium persulfate generated in step 1) is 2.02:1; the reaction temperature is 30 ~ 90 ℃; and the reaction time is 0.5 ~ 24 hours.

7. The method according to claim 1, wherein, In step 2), the reaction temperature is 40 ~ 70 ℃; the reaction time is 2 ~ 3 hours.

8. The method according to claim 1, wherein, In step 2), after obtaining an aqueous solution containing the intermediate dithiodiacetaldehyde, the pH of the reaction solution is adjusted to 4-5, and the reaction is carried out for 1-24 hours. Then, hydrogen peroxide and catalyst 1 are added, and the reaction is continued for a period of time. After filtration, catalyst 1 is removed, and the resulting reaction solution is used directly in step 3 without further processing.

9. The method according to claim 1, wherein, In step 2), after obtaining an aqueous solution containing the intermediate dithiodiacetaldehyde, the pH of the reaction solution is adjusted to 4 to 5, and the reaction is carried out for 4 to 6 hours.

10. The method according to claim 1, wherein, In step 2), The hydrogen peroxide is available in 30% or 50% concentration varieties; The amount of catalyst 1 added is 1-5% of the mass of the reaction solution; The reaction temperature is 30 ~ 100 ℃; The reaction time is 1 to 24 hours.

11. The method according to claim 1, wherein, In step 2), The hydrogen peroxide is available in 30% or 50% concentration varieties; The amount of catalyst 1 added is 2-3% of the mass of the reaction solution; The reaction temperature is 80 ℃; The reaction time is 3-5 hours.

12. The method according to claim 1, wherein, In step 3), catalyst 2 is added to the reaction solution obtained in step 2), and then hydrogen gas is introduced to carry out a reduction reaction to obtain a solution containing taurine product.

13. The method according to claim 12, wherein, In step 3), Catalyst 2 is 5% or 10% Pd / C, added at a rate of 1-10% of the reaction solution mass; The hydrogen pressure is 1 ~ 2 MPa; The reaction time is 1 to 4 hours; The reaction temperature is 20 ~ 100 ℃.

14. The method according to claim 1, wherein, In step 3), Catalyst 2 is 5% or 10% Pd / C, added at a rate of 2-3% of the reaction solution mass; The hydrogen pressure is 1 ~ 2 MPa; The reaction time is 2 to 3 hours; The reaction temperature is 60 ~ 65 ℃.

15. The method according to claim 1, wherein, In step 4), the mother liquor after crystallizing taurine is recycled, the crude taurine is returned to the crystallization process, the distilled water is returned to the HPF wet desulfurization section, and the remaining ammonium chloride is returned to step 2) for recycling, or can be sold externally.

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