A method for electrocatalytically co-processing industrial sulfur-containing flue gas and PET waste plastics into hydroxymethane sulfonate

Abstract

The application relates to a method for electrocatalytic synergic treatment of industrial sulfur-containing flue gas and conversion of PET waste plastics into hydroxymethanesulfonate, wherein the method comprises the following steps: introducing the industrial sulfur-containing flue gas into lye to obtain a treatment liquid, wherein the sulfur-containing flue gas contains sulfur oxides; hydrolyzing the waste PET plastics in the lye to obtain a PET hydrolysate containing ethylene glycol; mixing the treatment liquid and the PET hydrolysate to prepare an electrolyte; and performing electrolysis reaction to convert the ethylene glycol in the PET hydrolysate and the sulfur oxides into hydroxymethanesulfonate. The application synergically treats the industrial sulfur-containing flue gas and recycles the waste PET plastics, combines the sulfur-containing flue gas and the waste PET plastics to convert them into the high-value chemical hydroxymethanesulfonate, realizes the improvement of the recycling value of the waste PET plastics, fully utilizes the product in the industrial flue gas desulfurization process, and improves the utilization rate of the waste recycling and the economic benefits.

Description

Technical Field

[0001] The present invention belongs to the field of electrocatalysis technology, and more specifically, relates to a method for electrocatalytically co-processing industrial sulfur-containing flue gas and waste PET plastics into hydroxymethane sulfonate. Background Art

[0002] Industrial flue gas is an inevitable byproduct of nonferrous metal smelting processes. Industrial sulfur-containing flue gas, in particular, is considered a pollutant due to its high concentration of sulfur oxides. Sulfur dioxide, a typical sulfur oxide, is a major cause of acid rain. If not safely disposed of, it can corrode and damage soil, water, vegetation, and buildings. Therefore, recycling industrial sulfur-containing flue gas not only effectively reduces environmental pollution during industrial production but also serves as a key resource for the disposal of hazardous gases.

[0003] In recent years, the treatment of industrial sulfur-containing flue gas has primarily focused on desulfurization to meet emission standards, while also converting the sulfur into chemicals such as sulfuric acid and sulfates. Wet absorption is a key flue gas desulfurization technology. Its principle is to absorb SO2 from the sulfur-containing flue gas with an alkaline solution, producing a mixed solution containing sulfur oxides.

[0004] Chinese patent CN201711452293.7 discloses a method for producing sulfuric acid from smelting flue gas. This method involves drying deeply purified sulfur-containing flue gas in dilute sulfuric acid. The dried sulfur-containing flue gas is then fed into a converter containing a catalyst bed to convert the sulfur dioxide in the flue gas into sulfur trioxide. Finally, the flue gas is passed through sulfuric acid to produce concentrated sulfuric acid. This method is simple, easy to operate, and highly adaptable, but its final product is relatively conventional, requires high equipment requirements, and has limited economic value.

[0005] Chinese patent CN202311080318.0 discloses a method for separating and purifying fly ash pickling salt from sulfur-containing flue gas and its resource utilization. This method passes the sulfur-containing flue gas through a heat exchange treatment and an oxidation treatment, and then passes it into a fly ash pickling salt solution, and then obtains washed calcium sulfate and a washing liquid through separation, precipitation, and water washing. The washing liquid is mixed with the mother liquor in the first step and evaporated to obtain a saturated salt solution and a mixed salt. A sodium collector is added to the saturated salt solution and the mixed salt, and potassium sulfate and calcium chloride are finally obtained after flotation, separation, filtration, washing, and reaction. This method produces high-value chemicals, but its process is relatively cumbersome, requires the use of a sodium collector, and the product purity and yield are low.

[0006] The disposal of waste PET plastics has long been a hot topic of global concern. Traditional methods for treating waste PET plastics, such as incineration and landfilling, consume significant land resources and pose serious risks to soil, water, and the atmosphere. In recent years, electrocatalytic technology has demonstrated its potential in the reuse of waste PET plastics, enabling efficient and highly selective conversion of waste PET plastics into terephthalic acid (PTA) and ethylene glycol (EG) monomers. While this process typically produces formic acid and glycolic acid as the final products, while offering considerable economic benefits, the development of higher-value products is a growing trend in electrocatalytic waste PET plastics research.

[0007] Based on this, the present invention proposes a novel method for the synergistic treatment of industrial sulfur-containing flue gas and waste PET plastics, aiming to achieve safe solid waste disposal and a short-process for the production of high-value chemicals. This process first treats industrial sulfur-containing flue gas through wet absorption and then alkaline hydrolysis of waste PET plastics. Then, through electrocatalysis, sulfur oxides are further coupled to carbon atoms to form hydroxymethane sulfonates. Hydroxymethane sulfonates, as important compounds, are widely used as intermediates in drug synthesis, playing a key role in the synthesis of drugs such as isoniazid sodium sulfonate and carboxylic acid, thus occupying a key position in the pharmaceutical industry.

[0008] Under the guidance of green and sustainable global economic and social development, the rational disposal of solid waste and industrial waste gas is crucial to building a green, low-carbon, circular economic system. Based on this, the present invention not only combines the recycling of waste PET plastic with the treatment of industrial sulfur-containing flue gas, but also proposes a process for producing high-value chemicals in a short process. This not only effectively solves the environmental problems caused by industrial sulfur-containing flue gas and plastic waste, but also has high economic benefits, thereby promoting the development of a circular economy. Summary of the Invention

[0009] The purpose of the present invention is to coordinate the treatment of industrial sulfur-containing flue gas and the recycling of waste PET plastics, combine the sulfur-containing flue gas and waste PET plastics into high-value chemical hydroxymethane sulfonate, thereby improving the recycling value of waste PET plastics, and making full use of the products of the industrial flue gas desulfurization process to improve the waste recycling rate and economic benefits.

[0010] In order to achieve the purpose of the present invention, the present invention proposes a method for electrocatalytically co-processing industrial sulfur-containing flue gas and PET waste plastics into hydroxymethane sulfonate:

[0011] The following steps are involved:

[0012] S1. The industrial sulfur-containing flue gas is passed into an alkaline solution to obtain a treatment liquid, wherein the sulfur-containing flue gas contains sulfur oxides;

[0013] S2. hydrolyzing the waste PET plastic in an alkaline solution to obtain a PET hydrolyzate containing ethylene glycol;

[0014] S3. The treated liquid and the PET hydrolyzate are mixed to prepare an electrolyte, and the electrolysis reaction converts the ethylene glycol and sulfur-containing oxides in the PET hydrolyzate into hydroxymethane sulfonate.

[0015] Preferably, the industrial sulfur-containing flue gas in step S1 contains SO2 gas, the alkali solution is 0.1~4 mol / L NaOH or KOH solution, the flow rate of the sulfur-containing flue gas is 2~5 ml / s, and the introduction time is 10~60 min; the treatment liquid contains sulfite.

[0016] Preferably, the hydrolysis conditions of step S2 are: 2-6 mol / L NaOH or KOH solution, reaction temperature of 50-90°C, stirring speed of 100-500 rpm, reaction time of 6-24 hours, and solid-liquid ratio of 1:5-1:20 (g / mL).

[0017] Preferably, the waste PET plastic in step S2 is one or more of waste PET powder, waste PET plastic blocks or finished products of waste PET plastic.

[0018] Preferably, in the step S2, after the waste PET plastic is hydrolyzed with an alkaline solution, the hydrolyzate is adjusted to pH = 2.8~3.0, and after solid-liquid separation of the precipitated TPA, an acidic hydrolyzate containing ethylene glycol is obtained.

[0019] Preferably, the electrode system of step S3 consists of a working electrode, a counter electrode and a reference electrode; the working electrode is a metal oxide or hydroxide supported on carbon fiber paper or carbon cloth, the reference electrode is Ag / AgCl, and the counter electrode is a platinum mesh; wherein the metal of the working electrode includes: one or more of cobalt, nickel, manganese, copper or palladium.

[0020] Preferably, the electrolysis condition in step S3 is a constant voltage condition, and the voltage is 1.20-1.35 V (relative to the reference electrode Ag / AgCl) at room temperature.

[0021] Preferably, the electrolyte in step S3 comprises 0.01-0.1 M sulfite and 0.1-1 M ethylene glycol.

[0022] Compared with the prior art, the present invention has at least the following beneficial effects:

[0023] (1) The present invention synergizes the treatment of industrial sulfur-containing flue gas and waste PET plastics, and synthesizes hydroxymethane sulfonate using an electrocatalytic method. While producing high-value chemical products, it also upgrades the traditional industrial sulfur-containing flue gas treatment process, rationally utilizes the waste liquid generated during the desulfurization process, and prepares hydroxymethane sulfonate in a short process. The present invention simultaneously achieves efficient treatment of sulfur-containing flue gas and efficient recycling of waste PET plastics, with high economic benefits.

[0024] (2) The present invention collects sulfur oxide gas rich in sulfur-containing flue gas by alkaline solution to obtain sulfite, and waste PET plastic is hydrolyzed under alkaline conditions to obtain PET hydrolyzate containing ethylene glycol. The two alkaline solutions are combined and placed in an electrochemical synthesis system, and the sulfite and ethylene glycol produced by the hydrolysis of PET are electrocatalytically synthesized by an electrochemical method, and a CS coupling reaction is carried out to prepare hydroxymethane sulfonate.

[0025] (3) The present invention innovatively proposes a process for electrochemically synthesizing hydroxymethane sulfonate, which has high synthesis efficiency and selectivity, and can produce high-yield hydroxymethane sulfonate in a short process. At the same time, the present invention proposes to select specific metal oxides or metal hydroxides as catalysts to make working electrodes, and select appropriate acidic catalytic conditions to achieve efficient conversion synthesis. In addition, compared with the traditional hydroxymethane sulfonate manufacturing process, the process and equipment are simpler, and the output value is high, with higher economic value and social value, and has industrial production potential and broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Flowchart of the method of the present invention.

[0027] Figure 2 This is the SEM image of the manganese dioxide used in Example 1.

[0028] Figure 3 This is the XRD pattern of manganese dioxide used in Example 1.

[0029] Figure 4 This is a linear sweep voltammetry (LSV) curve test of the electrolysis system of Example 1.

[0030] Figure 5 is the electrolysis reaction product in Example 2 1 H NMR.

[0031] Figure 6 The solution after hydrolysis in step S2 in Example 4 1 H NMR.

[0032] Figure 7 This is a linear sweep voltammetry (LSV) curve test of the electrolysis reaction of Comparative Example 1.

[0033] Figure 8 The figure is the test result of the yield of hydroxymethanesulfonate in Comparative Example 2. DETAILED DESCRIPTION

[0034] The present invention is further described in detail below through examples to illustrate the features and advantages of the present invention, but does not limit the embodiments of the present invention.

[0035] like Figure 1 As shown, the present invention proposes a method for electrocatalytically co-processing industrial sulfur-containing flue gas and PET waste plastics into hydroxymethane sulfonate, comprising the following steps:

[0036] S1. The industrial sulfur-containing flue gas is passed into an alkaline solution to obtain a treatment liquid, wherein the sulfur-containing flue gas contains sulfur oxides;

[0037] S2. hydrolyzing the waste PET plastic in an alkaline solution to obtain a PET hydrolyzate containing ethylene glycol;

[0038] S3. The treated liquid and the PET hydrolyzate are mixed to prepare an electrolyte, and the electrolysis reaction converts the ethylene glycol and sulfur-containing oxides in the PET hydrolyzate into hydroxymethane sulfonate.

[0039] The method of the present invention comprises the following steps: firstly introducing industrial sulfur-containing flue gas into an alkaline solution to obtain a treated liquid, wherein the sulfur-containing flue gas contains sulfur oxides; performing a hydrolysis reaction on waste PET plastic under alkaline conditions and then adjusting the pH to obtain a PET hydrolyzate containing ethylene glycol; introducing the treated liquid, adjusting the pH and then using it as an electrolyte; electrolyzing the treated liquid under an electrode system to perform a CS coupling reaction, thereby converting the ethylene glycol in the PET alkaline hydrolyzate into hydroxymethane sulfonate.

[0040] Therefore, the present invention combines the sulfur-containing flue gas and waste PET plastics into the high-value chemical hydroxymethane sulfonate by coordinating the treatment of industrial sulfur-containing flue gas, the waste PET plastic recycling process and the electrochemical method, thereby improving the recycling value of the waste PET plastics and making full use of the products of the industrial flue gas desulfurization process, thereby improving the utilization rate and economic benefits of the waste cycle.

[0041] In the present invention, the industrial sulfur-containing flue gas in step S1 contains SO2 gas. Flue gas containing SO2 primarily originates from the following combustion or industrial processing processes: coal combustion, oil combustion, natural gas combustion, sulfide ore roasting, carbon disulfide (CS2) production, or sulfite production (e.g., pulp bleaching processes).

[0042] Preferably, the alkali solution is 0.1-4 mol / L NaOH or KOH solution, the sulfur-containing flue gas is introduced at a flow rate of 2-5 ml / s, and the introduction time is 10-60 min; the formed treatment solution contains sulfite.

[0043] In the present invention, the main component of the waste PET plastic in step S2 is PET.

[0044] Preferably, the waste PET plastic in step S2 is one or more of waste PET powder, waste PET plastic chunks, or finished products of waste PET plastic. The finished products of waste PET plastic can be waste products such as packaging bottles, packaging boxes, and films. The finished products of waste PET plastic can be crushed to obtain PET powder or sheared to obtain waste PET plastic chunks.

[0045] Preferably, the hydrolysis conditions in step S2 are: 2-6 mol / L NaOH or KOH solution, a reaction temperature of 50-90°C, a stirring speed of 100-500 rpm, a reaction time of 6-24 hours, and a solid-to-liquid ratio of 1:5-1:20 (g / mL). The concentration of the alkaline solution and reaction conditions can be adjusted appropriately for the specific waste PET plastic. For example, for powdered PET plastic, the hydrolysis reaction can be achieved using a relatively low alkaline solution concentration, a relatively low temperature, a relatively fast reaction time, and a small amount of solution within the optional parameter range of step S2.

[0046] Preferably, in step S2, the waste PET plastic is hydrolyzed with an alkaline solution, the hydrolyzate is adjusted to pH = 2.8-3.0, and the precipitated TPA is separated by solid-liquid separation to obtain an acidic hydrolyzate containing ethylene glycol.

[0047] Preferably, after the treatment solution and the PET hydrolyzate are mixed in step S3, the electrolyte needs to be adjusted to a weakly acidic electrolyte before the electrolysis reaction is carried out. More preferably, the suitable electrolysis condition is a pH value of 5.6 to 5.7.

[0048] Preferably, the acidic regulator and alkaline regulator in the pH adjustment step in the method of the present invention can be sulfuric acid, hydrochloric acid, sodium hydroxide or potassium hydroxide.

[0049] Preferably, the electrolyte in step S3 comprises 0.01-0.1 M sulfite and 0.1-1 M ethylene glycol.

[0050] In order to ensure the conductivity of the electrolyte, some electrolytes may be optionally added, such as common soluble conductive salts such as sulfate and chloride.

[0051] Preferably, the electrode system of step S3 consists of a working electrode, a counter electrode and a reference electrode; the working electrode is a metal oxide or hydroxide supported on carbon fiber paper or carbon cloth, the reference electrode is Ag / AgCl, and the counter electrode is a platinum mesh; wherein the metal of the working electrode includes: one or more of cobalt, nickel, manganese, copper or palladium.

[0052] The carbon fiber paper or carbon cloth acts as a conductive carrier, stably loading the metal catalyst on its surface. Furthermore, to achieve effective loading of the metal oxide or hydroxide, the carrier can be pretreated by conventional surface pretreatment methods such as water washing, alcohol cleaning, acid washing, alkaline washing, or polishing.

[0053] Optionally, the metal oxide or hydroxide is loaded on the carrier in the form of flakes or particles. More preferably, the metal oxide or hydroxide is in situ deposited by chemical deposition and dispersed on the carrier in nanometer size to provide an active surface with a larger specific surface area and stronger adhesion.

[0054] To achieve the loading of the metal oxide or hydroxide on the carrier carbon fiber paper or carbon cloth, optional in-situ deposition methods include liquid phase deposition, liquid phase deposition combined with high temperature calcination, or chemical impregnation combined with high temperature calcination.

[0055] Preferably, the metal oxide is cobalt oxide, nickel oxide, copper oxide, manganese oxide or palladium oxide; and the metal hydroxide is preferably cobalt hydroxide, nickel hydroxide, copper hydroxide, manganese hydroxide or palladium hydroxide.

[0056] Preferably, the electrolysis condition in step S3 is a constant voltage condition, and the voltage is 1.20-1.35 V (relative to the reference electrode Ag / AgCl) at room temperature.

[0057] The method of the present invention is explained in detail below with reference to specific embodiments.

[0058] Example 1

[0059] This embodiment provides the following method for electrocatalytically co-processing industrial sulfur-containing flue gas and PET waste plastics into hydroxymethane sulfonate, comprising:

[0060] S1. Passing industrial sulfur-containing flue gas into alkaline solution to obtain a treated liquid, wherein the sulfur-containing flue gas contains sulfur oxides.

[0061] The industrial sulfur-containing flue gas is the flue gas of sulfide ore roasting, and the sulfur oxide in the flue gas is SO2 gas. The alkali solution used for SO2 gas capture includes 0.1 mol / L NaOH solution. The flow rate of the sulfur-containing flue gas is 5 ml / s, and the feeding time is 30 min. A treated liquid is obtained, and the treated liquid contains sulfite.

[0062] S2. The waste PET plastic is subjected to hydrolysis under alkaline conditions to obtain a PET hydrolysate containing ethylene glycol.

[0063] The waste PET plastic is a 200-mesh waste PET powder. The alkaline solution for treating the waste PET plastic is 4 mol / L NaOH solution. The reaction temperature is 70°C. The stirring speed is 300 rpm. The reaction time is 16 hours. The solid-liquid ratio is 1:20.

[0064] After the waste PET plastic is hydrolyzed by the alkaline solution, the hydrolysate is adjusted to pH = 2.8. After the precipitated TPA is separated from the solid-liquid, an acidic hydrolysate containing ethylene glycol is obtained.

[0065] S3. The treated liquid and the PET hydrolysate are mixed to prepare an electrolyte. An electrolysis reaction converts ethylene glycol in the PET hydrolysate and sulfur-containing oxide into hydroxymethanesulfonate.

[0066] After the treated liquid and the PET hydrolysate are mixed, further pH adjustment is required. The acidic hydrolysate is adjusted to pH 5.65 and used for subsequent electrolysis reaction.

[0067] The electrolysis reaction uses a three-electrode system composed of a working electrode, a counter electrode, and a reference electrode. The working electrode is manganese dioxide loaded on carbon cloth. The reference electrode is Ag / AgCl, and the counter electrode is platinum mesh.

[0068] The preparation method of the working electrode for the electrolysis reaction is as follows:

[0069] 1) Preparation of deposition solution: weigh 0.01 g of potassium permanganate, 0.1 g of manganese sulfate, and 0.02 g of potassium persulfate, and dissolve them in 20 ml of deionized water. Stir magnetically until completely dissolved. Adjust the pH of the solution to 8-11 (add dilute sulfuric acid or sodium hydroxide solution).

[0070] 2) Chemical deposition: immerse a 1 cm*1 cm carbon cloth in the deposition solution, ensuring that the carbon cloth is completely immersed. Place the deposition solution on a magnetic stirrer and stir at an appropriate speed while controlling the reaction temperature at 75°C. React for 6 hours. After the reaction is completed, remove the carbon cloth and rinse it with deionized water to remove unreacted substances attached to the surface.

[0071] 3) Drying and Calcination: The rinsed carbon cloth was placed in an oven and dried at 60°C to a constant weight. It was then calcined in a tube furnace at 300°C for 2 hours and allowed to cool naturally to obtain manganese dioxide supported on the carbon cloth.

[0072] Figure 2 To prepare the SEM image of manganese dioxide loaded on carbon cloth, it can be seen from the SEM image that the manganese dioxide is in the form of nanosheets. Figure 3 The XRD pattern of the deposit scraped off the carbon cloth proves that it is manganese dioxide.

[0073] The electrolysis reaction was carried out at room temperature. The electrolyte used contained 0.1 M K2SO4, 20 mM NaSO3 and 200 mM ethylene glycol. The voltage was 1.35 V vs. Ag / AgCl and the reaction time was 240 min.

[0074] The solution after the electrolysis reaction was analyzed and the yield of hydroxymethanesulfonate was 0.2 mol cm - 2 h -1 , the purity of hydroxymethane sulfonate is 73%.

[0075] Yield = number of moles of hydroxymethanesulfonate produced by the reaction / (time * working electrode reaction area (1 cm * 1 cm));

[0076] Purity = mass of hydroxymethane sulfonate in the product / (mass of hydroxymethane sulfonate in the product + other impurities in the product).

[0077] like Figure 4 Shown are linear sweep voltammetry (LSV) curves collected in the electrolysis system of this embodiment. It can be seen that the initial oxidation potential of the electrolysis system of this embodiment is 0.425 V. The curve marked with the oxygen evolution reaction was obtained in an electrolyte containing only the same concentration of sulfite and no ethylene glycol, and using the same electrode system as Example 1.

[0078] Example 2

[0079] This embodiment provides the following method for electrocatalytically co-processing industrial sulfur-containing flue gas and PET waste plastics into hydroxymethane sulfonate, comprising:

[0080] S1. Passing industrial sulfur-containing flue gas into alkaline solution to obtain a treated liquid, wherein the sulfur-containing flue gas contains sulfur oxides.

[0081] The industrial sulfur-containing flue gas is the flue gas from the roasting of sulfide ore, the sulfur oxides in the flue gas are SO2 gas, the alkali solution used to capture the SO2 gas includes 1 mol / L NaOH solution, the inlet flow rate of the sulfur-containing flue gas is 4 ml / s, the inlet time is 20 min, and an aqueous solution of sulfur oxides is obtained.

[0082] S2. Waste PET plastic is hydrolyzed under alkaline conditions to obtain a PET hydrolyzate containing ethylene glycol.

[0083] The waste PET plastic was 200-mesh waste PET powder. The alkaline solution used to treat the waste PET plastic was a 3 mol / L NaOH solution. The reaction temperature was 60°C, the stirring speed was 400 rpm, the reaction time was 18 hours, and the solid-liquid ratio was 1:10.

[0084] After the waste PET plastic is hydrolyzed with an alkaline solution, the hydrolyzate is adjusted to pH = 3.0. After solid-liquid separation of the precipitated TPA, an acidic hydrolyzate containing ethylene glycol is obtained.

[0085] S3. The treated liquid and the PET hydrolyzate are mixed to prepare an electrolyte, and the electrolysis reaction converts the ethylene glycol and sulfur-containing oxides in the PET hydrolyzate into hydroxymethane sulfonate.

[0086] Among them, after the treatment liquid and the PET hydrolyzate are mixed, further pH adjustment treatment is required to adjust the pH to 5.65 into an acidic hydrolyzate for subsequent electrolysis reaction.

[0087] The electrolysis reaction uses a three-electrode system consisting of a working electrode, a counter electrode, and a reference electrode. The working electrode is nickel hydroxide supported on carbon cloth, the reference electrode is Ag / AgCl, and the counter electrode is a platinum mesh.

[0088] The preparation method of the working electrode for the electrolysis reaction is as follows:

[0089] 1) Prepare the deposition solution: Dissolve 0.18 mmol NiCl2·6H2O, 1 mmol urea, and 0.8 mmol NH4F in 20 ml deionized water.

[0090] 2) Chemical Deposition: The deposition solution was poured into a 10 ml autoclave containing carbon cloth. The autoclave was sealed and heated to 180°C for 6 hours. After the reaction was complete, the carbon cloth was removed and rinsed with water and ethanol.

[0091] 3) Drying: A 1 cm*1 cm carbon cloth was vacuum dried at 60°C for 4 hours to obtain nickel hydroxide supported on the carbon cloth.

[0092] The electrolysis reaction was carried out at room temperature. The electrolyte used contained 0.1 M K2SO4, 25 mM Na2SO3 and 250 mM ethylene glycol. The voltage was 1.3 V vs. Ag / AgCl and the reaction time was 190 min.

[0093] The electrolyte after electrocatalytic synergistic treatment in Example 2 was diluted and then subjected to nuclear magnetic resonance detection. The results are as follows: Figure 5 As shown, the main product in the electrolyte is hydroxymethanesulfonate (HMS), in which dimethyl sulfoxide (DMSO) is added as a solvent for testing. The solution after the electrolysis reaction was analyzed and the yield of hydroxymethanesulfonate was 0.26 molcm -2 h -1 , the purity of hydroxymethane sulfonate is 75%.

[0094] Example 3

[0095] This embodiment provides the following method for electrocatalytically co-processing industrial sulfur-containing flue gas and PET waste plastics into hydroxymethane sulfonate, comprising:

[0096] S1. Passing industrial sulfur-containing flue gas into alkaline solution to obtain a treated liquid, wherein the sulfur-containing flue gas contains sulfur oxides.

[0097] The industrial sulfur-containing flue gas is the flue gas from the roasting of sulfide ore, the sulfur oxides in the flue gas are SO2 gas, the alkaline solution used for capturing the SO2 gas includes a 2 mol / L NaOH solution, the inlet flow rate of the sulfur-containing flue gas is 3 ml / s, the inlet time is 20 min, and an aqueous solution of sulfur oxides is obtained.

[0098] S2. Waste PET plastic is hydrolyzed under alkaline conditions to obtain a PET hydrolyzate containing ethylene glycol.

[0099] The waste PET plastic is 200-mesh waste PET powder.

[0100] The alkaline solution used to treat waste PET plastics was a 2 mol / L NaOH solution, the reaction temperature was 80°C, the stirring speed was 300 rpm, the reaction time was 12 hours, and the solid-liquid ratio was 1:5.

[0101] After the waste PET plastic is hydrolyzed with an alkaline solution, the hydrolyzate is adjusted to pH = 2.9. After solid-liquid separation of the precipitated TPA, an acidic hydrolyzate containing ethylene glycol is obtained.

[0102] S3. The treated liquid and the PET hydrolyzate are mixed to prepare an electrolyte, and the electrolysis reaction converts the ethylene glycol and sulfur-containing oxides in the PET hydrolyzate into hydroxymethane sulfonate.

[0103] Among them, after the treatment liquid and the PET hydrolyzate are mixed, further pH adjustment treatment is required to adjust the pH to 5.65 into an acidic hydrolyzate for subsequent electrolysis reaction.

[0104] The electrolysis reaction uses a three-electrode system consisting of a working electrode, a counter electrode, and a reference electrode. The working electrode is copper oxide supported on carbon fiber paper, the reference electrode is Ag / AgCl, and the counter electrode is a platinum mesh.

[0105] The preparation method of the working electrode for the electrolysis reaction is as follows:

[0106] 1) Prepare sedimentation solution: Prepare 20 ml of 0.06 M copper nitrate solution.

[0107] 2) Chemical Deposition: Immerse the carbon fiber paper in a copper nitrate solution, maintain it in a constant temperature water bath at 50°C, and stir for 24 hours to ensure that the copper nitrate is fully adsorbed on the surface of the carbon fiber paper. Remove the impregnated carbon fiber paper and rinse it with deionized water to remove any unadsorbed copper nitrate. Place the copper nitrate-loaded carbon fiber paper in an oven and dry it at 60°C to constant weight.

[0108] 3) Drying and Calcination: The dried carbon fiber paper is placed in a muffle furnace and calcined at 400°C for 4 hours to decompose the copper nitrate and convert it into copper oxide. After calcination, the carbon fiber paper is removed and placed in an oven again at 60°C to dry to a constant weight. This results in copper oxide supported on the carbon fiber paper.

[0109] The electrolysis reaction voltage was 1.25 V vs. Ag / AgCl, the electrolyte used contained 0.1 M K2SO4, 20 mM NaSO3, and 200 mM ethylene glycol, and the reaction time was 300 min. Analysis of the solution after the electrolysis reaction revealed a yield of 0.23 mol cm-1 of hydroxymethanesulfonate. -2 h -1 , the purity of hydroxymethane sulfonate is 71%.

[0110] Example 4

[0111] This embodiment provides the following method for electrocatalytically co-processing industrial sulfur-containing flue gas and PET waste plastics into hydroxymethane sulfonate, comprising:

[0112] S1. Passing industrial sulfur-containing flue gas into alkaline solution to obtain a treated liquid, wherein the sulfur-containing flue gas contains sulfur oxides.

[0113] The industrial sulfur-containing flue gas is the flue gas from the roasting of sulfide ore, the sulfur oxides in the flue gas are SO2 gas, the alkaline solution used to capture the SO2 gas includes a 3 mol / L NaOH solution, the flow rate of the sulfur-containing flue gas is 2 ml / s, the introduction time is 50 min, and a treatment liquid is obtained, which contains sulfite.

[0114] S2. Waste PET plastic is hydrolyzed under alkaline conditions to obtain a PET hydrolyzate containing ethylene glycol.

[0115] The waste PET plastic was 200-mesh waste PET powder. The alkaline solution used to treat the waste PET plastic was a 5 mol / L NaOH solution. The reaction temperature was 50°C, the stirring speed was 500 rpm, the reaction time was 20 hours, and the solid-liquid ratio was 1:15.

[0116] The specific operation of pH adjustment treatment is to hydrolyze the waste PET plastic with alkaline solution and adjust the hydrolyzate to pH = 3.0. After solid-liquid separation of precipitated TPA, an acidic hydrolyzate containing ethylene glycol is obtained; the acidic hydrolyzate with pH adjusted to 5.65 is used for subsequent electrolysis reaction. The PET alkaline hydrolyzate is separated after pH adjustment and then subjected to nuclear magnetic resonance detection. The results are as follows Figure 6 As shown, it is proved that the main substance in the solution after PET hydrolysis and separation is ethylene glycol (EG).

[0117] S3. The treated liquid and the PET hydrolyzate are mixed to prepare an electrolyte, and the electrolysis reaction converts the ethylene glycol and sulfur-containing oxides in the PET hydrolyzate into hydroxymethane sulfonate.

[0118] Among them, after the treatment liquid and the PET hydrolyzate are mixed, further pH adjustment treatment is required to adjust the pH to 5.65 into an acidic hydrolyzate for subsequent electrolysis reaction.

[0119] The electrolysis reaction uses a three-electrode system consisting of a working electrode, a counter electrode, and a reference electrode. The working electrode is copper hydroxide supported on carbon fiber paper, the reference electrode is Ag / AgCl, and the counter electrode is a platinum mesh.

[0120] The preparation method of the working electrode for the electrolysis reaction is as follows:

[0121] 1) Prepare sedimentation solution: Prepare 20 ml of a solution containing 0.1 M copper sulfate and 0.2 M sodium hydroxide.

[0122] 2) Chemical deposition: immerse the 1 cm * 1 cm carbon fiber paper into the copper sulfate deposition solution, and evenly distribute the solution on the surface of the carbon fiber paper by magnetic stirring, keep for 30 minutes, to ensure that the copper ions are fully adsorbed. Take out the carbon fiber paper immersed in copper sulfate, drain the excess solution, and then quickly immerse it in sodium hydroxide solution. At this time, a precipitation reaction of copper hydroxide will occur on the surface of the carbon fiber paper. Keep for 10 minutes, stir to promote uniform reaction.

[0123] 3) Drying: after the reaction is completed, the carbon fiber paper is taken out, washed with deionized water to remove unreacted chemicals and impurities on the surface. The carbon fiber paper loaded with copper hydroxide is placed in an oven at 60°C and dried to constant weight to remove excess water, obtaining carbon fiber paper loaded with copper hydroxide.

[0124] The electrolysis reaction voltage is 1.25 V vs. Ag / AgCl, and the electrolyte used contains 0.1 M K2SO4, 25 mM NaSO3, 250 mM EG, and the reaction time is 200 min.

[0125] The solution after the reaction is tested, and the yield of hydroxymethanesulfonate is 0.29 mol cm -2 h -1 , and the purity of hydroxymethanesulfonate is 72%.

[0126] Example 5

[0127] The present embodiment provides a method for electrocatalytic synergistic treatment of industrial sulfur-containing flue gas and conversion of PET waste plastics into hydroxymethanesulfonate, comprising:

[0128] S1. Pass the industrial sulfur-containing flue gas into the lye to obtain a treated solution, wherein the sulfur-containing flue gas contains sulfur oxides.

[0129] Wherein the industrial sulfur-containing flue gas is the flue gas of sulfide ore roasting, and the sulfur oxides in the flue gas are SO2 gas, the lye used for SO2 gas capture includes 4 mol / L NaOH solution, the flow rate of the sulfur-containing flue gas is 4 ml / s respectively, the time of passing in is 10 min, and the treated solution containing sulfite is obtained.

[0130] S2. The waste PET plastics are subjected to hydrolysis reaction under alkaline conditions to obtain PET hydrolysis solution containing ethylene glycol.

[0131] Wherein the waste PET plastics are 200 mesh waste PET powder, the alkaline solution for treating the waste PET plastics is 6 mol / L NaOH solution, the reaction temperature is 70°C, the stirring speed is 200 rpm, the reaction time is 6 hours, and the solid-liquid ratio is 1:8.

[0132] The pH adjustment treatment is specifically operated as follows: after the waste PET plastic is hydrolyzed by an alkaline solution, the hydrolysis liquid is adjusted to pH = 2.9, and after the precipitated TPA is separated from the solid-liquid, the acid hydrolysis liquid containing ethylene glycol is obtained.

[0133] S3. The treatment liquid and the PET hydrolysis liquid are mixed to prepare an electrolyte, and an electrolysis reaction converts the ethylene glycol and the sulfur-containing oxide in the PET hydrolysis liquid into hydroxymethanesulfonate.

[0134] Further pH adjustment treatment is required after the treatment liquid and the PET hydrolysis liquid are mixed, and the acid hydrolysis liquid is adjusted to pH 5.65, which is used for subsequent electrolysis reaction.

[0135] The electrolysis reaction adopts a three-electrode system, which is composed of a working electrode, a counter electrode and a reference electrode. The working electrode is cobalt oxide loaded on carbon fiber paper, the reference electrode is Ag / AgCl, and the counter electrode is platinum mesh.

[0136] The preparation method of the working electrode of the electrolysis reaction is as follows:

[0137] 1) Preparation of deposition solution: prepare 20 ml of 0.06 M cobalt nitrate solution.

[0138] 2) Chemical deposition: immerse 1 cm*1 cm carbon fiber paper in the cobalt nitrate solution, keep it in a constant temperature water bath at 50 ℃ and stir for 24 hours to ensure that the cobalt nitrate is fully adsorbed on the surface of the carbon fiber paper. Take out the immersed carbon fiber paper and rinse it with deionized water to remove the unadsorbed cobalt nitrate on the surface.

[0139] 3) Drying and calcination: place the carbon fiber paper loaded with cobalt nitrate in an oven and dry it at 60 ℃ until the weight is constant. Place the dried carbon fiber paper in a muffle furnace and calcine it at 500 ℃ for 4 hours to decompose the cobalt nitrate and convert it into cobalt oxide. After the calcination is completed, take out the carbon fiber paper and place it in the oven again to dry it at 60 ℃ until the weight is constant, and obtain the cobalt oxide loaded on the carbon fiber paper.

[0140] The electrolysis reaction voltage is 1.3 V vs. Ag / AgCl, the electrolyte used contains 0.1 M K2SO4, 20 mM NaSO3, 200 mM ethylene glycol, and the reaction time is 260 min.

[0141] The yield of hydroxymethanesulfonate is 0.21 mol cm -2 h -1 The purity of hydroxymethanesulfonate is 78%.

[0142] Example 6

[0143] The embodiment provides a method for electrocatalytic synergistic treatment of industrial sulfur-containing flue gas and conversion of PET waste plastics into hydroxymethanesulfonate, which comprises the following steps:

[0144] S1. The industrial sulfur-containing flue gas is introduced into an alkali solution to obtain a treatment liquid, wherein the sulfur-containing flue gas contains sulfur oxides.

[0145] The industrial sulfur-containing flue gas is the flue gas of sulfide ore roasting, the sulfur oxide in the flue gas is SO2 gas, the alkali solution used for SO2 gas capture comprises 2 mol / L NaOH solution, the introduction flow rate of the sulfur-containing flue gas is 5 ml / s, the introduction time is 30 min, the treatment liquid is obtained, and the treatment liquid contains sulfite.

[0146] S2. The waste PET plastics are subjected to hydrolysis under an alkaline condition to obtain a PET hydrolysate containing ethylene glycol.

[0147] The waste PET plastics are 200-mesh waste PET powder, the alkaline solution for treating the waste PET plastics is 4 mol / L NaOH solution, the reaction temperature is 90°C, the stirring speed is 400 rpm, and the reaction time is 8 hours.

[0148] The specific operation of the pH adjustment treatment is that after the waste PET plastics are subjected to hydrolysis in the alkaline solution, the hydrolysate is adjusted to pH = 2.8, and after the precipitated TPA is separated from the solid-liquid, the acid hydrolysate containing ethylene glycol is obtained.

[0149] S3. The treatment liquid and the PET hydrolysate are mixed to prepare an electrolyte, and an electrolysis reaction is performed to convert the ethylene glycol in the PET hydrolysate and the sulfur oxides into hydroxymethanesulfonate.

[0150] The treatment liquid and the PET hydrolysate are mixed and further subjected to pH adjustment treatment, and the acid hydrolysate is adjusted to pH 5.65 and used for subsequent electrolysis reaction.

[0151] The electrolysis reaction adopts a three-electrode system, which comprises a working electrode, a counter electrode and a reference electrode. The working electrode is a palladium oxide loaded on carbon cloth, the reference electrode is Ag / AgCl, and the counter electrode is a platinum mesh.

[0152] The preparation method of the working electrode of the electrolysis reaction is as follows:

[0153] 1) Preparation of deposition solution: 0.01 g of potassium permanganate, 0.1 g of palladium sulfate and 0.02 g of potassium persulfate are dissolved in 20 ml of deionized water, and the solution is magnetically stirred until completely dissolved, and the pH value of the solution is adjusted to 8-11.

[0154] 2) Chemical Deposition: Immerse a 1cm x 1cm carbon cloth in the deposition solution, ensuring it is completely submerged. Place the deposition solution on a magnetic stirrer and stir at an appropriate speed while maintaining the reaction temperature at 75°C. Allow to react for 6 hours. Remove the carbon cloth and rinse with deionized water to remove any unreacted material adhering to the surface.

[0155] 3) Drying and Calcination: The rinsed carbon cloth was placed in an oven and dried at 60°C to constant weight. It was then calcined in a tube furnace at 300°C for 2 hours and allowed to cool naturally. It was then calcined in a tube furnace at 500°C for 3 hours to remove impurities. The palladium oxide supported on the carbon cloth was then removed after cooling naturally.

[0156] The electrolysis reaction voltage was 1.35 V vs. Ag / AgCl, the electrolyte used contained 0.1 M K2SO4, 20 mMNaSO3, and 200 mM ethylene glycol, and the reaction time was 280 min.

[0157] The solution after the electrolysis reaction was analyzed and the yield of hydroxymethanesulfonate was 0.25 mol cm - 2 h -1 , the purity of hydroxymethane sulfonate is 76%.

[0158] Comparative Example 1

[0159] The difference from Example 1 is that the working electrode used in step S3 is changed to Au / Ni(OH)2 supported by nickel foam.

[0160] The preparation method of the working electrode for the electrolysis reaction is as follows:

[0161] First, a 1cm x 1cm nickel foam electrode was immersed in a mixed solution of 0.05 mM AuCl₃ and 0.5 M NaCl at 25°C for 6 hours. The pre-existing product was then washed with ultrapure water and ethanol. Finally, the nickel foam was annealed in an oven at 200°C for 2 hours to prepare the Au / Ni(OH)₂ composite catalyst supported on the nickel foam. The Ni(OH)₂ layer formed a porous material on the surface of the nickel foam electrode, which served as a support for a layer of metallic Au.

[0162] The electrolyte used contained 0.1 M K2SO4, 20 mM NaSO3, and 200 mM ethylene glycol, and the collected linear sweep voltammetry (LSV) curves were tested, as shown in Figure 5. Figure 7 The test results of EG+SO3 are shown, while Figure 7The curve labeled "oxygen evolution reaction" is shown for reference. This linear sweep voltammetry curve was obtained under the same electrode conditions as in this comparative example, but with the electrolyte containing only sulfite at the same concentration and no ethylene glycol. It can be seen that the working electrode in this comparative example cannot catalyze the electrolytic reaction to produce hydroxymethane sulfonate. This demonstrates that the metal hydroxide or oxide supported on the working electrode of the present invention can effectively achieve electrocatalytic synergistic treatment of industrial sulfur-containing flue gas and PET waste plastics to convert them into hydroxymethane sulfonate.

[0163] Comparative Example 2

[0164] The difference from Example 1 is that the pH value of the electrolyte used for the electrolysis reaction in step S3 is different, and multiple groups of comparative experiments are set up, with pH values ​​of 5.3, 5.4, 5.5, 5.6, 5.7, 5.8 and 5.9 respectively.

[0165] The yield of hydroxymethanesulfonate under different pH conditions is as follows Figure 8 As shown, by comparing different pH conditions and testing the yield of hydroxymethane sulfonate, it can be seen that when the pH of the electrolyte is 5.6-5.7, the yield of hydroxymethane sulfonate is high, and when the pH value is lower or higher than the range of 5.6-5.7, the catalytic efficiency of the catalyst is significantly reduced. Therefore, the optimal electrolysis reaction condition of the present invention is a weakly acidic condition with a pH of 5.6-5.7.

[0166] The above embodiments are preferred implementations of the present invention, but the implementations of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A method for electrocatalytically co-processing industrial sulfur-containing flue gas and PET waste plastics into hydroxymethane sulfonate, characterized in that: The following steps are involved: S1. The industrial sulfur-containing flue gas is passed into an alkaline solution to obtain a treatment liquid, wherein the sulfur-containing flue gas contains sulfur oxides; S2. hydrolyzing the waste PET plastic in an alkaline solution to obtain a PET hydrolyzate containing ethylene glycol; S3. The treated liquid and the PET hydrolyzate are mixed to form an electrolyte, and the electrolytic reaction converts ethylene glycol and sulfur-containing oxides into hydroxymethane sulfonate; the electrode system of step S3 consists of a working electrode, a counter electrode, and a reference electrode; the working electrode is a metal oxide or hydroxide supported on a carrier, wherein the carrier is carbon fiber paper or carbon cloth, the pH of the electrolyte is 5.6-5.7, and the metal of the working electrode includes one or more of cobalt, nickel, manganese, copper, or palladium.

2. A method for electrocatalytically co-processing industrial sulfur-containing flue gas and PET waste plastics into hydroxymethane sulfonate according to claim 1, characterized in that: The industrial sulfur-containing flue gas in step S1 contains SO2 gas, the alkali solution is 0.1~4mol / L NaOH or KOH solution, the sulfur-containing flue gas is introduced at a flow rate of 2~5 ml / s, and the introduction time is 10~60 min; the SO2 gas is converted into sulfite.

3. A method for electrocatalytically co-processing industrial sulfur-containing flue gas and PET waste plastics into hydroxymethane sulfonate according to claim 1, characterized in that: The hydrolysis conditions of step S2 are: 2-6 mol / L NaOH or KOH solution, reaction temperature of 50-90°C, stirring speed of 100-500 rpm, reaction time of 6-24 hours, and solid-liquid ratio of 1:5-1:20 g / mL.

4. A method for electrocatalytically co-processing industrial sulfur-containing flue gas and PET waste plastics into hydroxymethane sulfonate according to claim 1, characterized in that: The waste PET plastic in step S2 is one or more of waste PET powder, waste PET plastic blocks, or finished products of waste PET plastic.

5. A method for electrocatalytically co-processing industrial sulfur-containing flue gas and PET waste plastics into hydroxymethane sulfonate according to claim 1, characterized in that: In step S2, the waste PET plastic is hydrolyzed with an alkaline solution, and the hydrolyzate is adjusted to a pH of 2.8 to 3.

0. After solid-liquid separation to remove the precipitated TPA, an acidic hydrolyzate containing ethylene glycol is obtained.

6. A method for electrocatalytically co-processing industrial sulfur-containing flue gas and PET waste plastics into hydroxymethane sulfonate according to claim 1, characterized in that: The reference electrode was Ag / AgCl, and the counter electrode was a platinum mesh.

7. A method for electrocatalytically co-processing industrial sulfur-containing flue gas and PET waste plastics into hydroxymethane sulfonate according to claim 1, characterized in that: The electrolysis condition of the S3 step is a constant voltage condition, and the voltage is 1.20~1.35V, and the voltage is the voltage relative to the reference electrode Ag / AgCl, and the room temperature condition.

8. A method for electrocatalytically co-processing industrial sulfur-containing flue gas and PET waste plastics into hydroxymethane sulfonate according to claim 1, characterized in that: The electrolyte in step S3 includes 0.01-0.1 M sulfite and 0.1-1 M ethylene glycol.

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