Method for co-processing industrial sulfur-containing flue gas and upgrading and converting PET waste plastics into hydroxyl methane sulfonate through electro-catalysis

Abstract

The invention relates to a method for treating industrial sulfur-containing flue gas and upgrading and converting PET (polyethylene terephthalate) waste plastics into hydroxyl methane sulfonate through electro-catalysis co-treatment, which comprises the following steps: introducing the industrial sulfur-containing flue gas into alkali liquor to obtain a treatment solution, the sulfur-containing flue gas containing sulfur oxides; the method comprises the following steps: hydrolyzing waste PET plastic in alkali liquor to obtain PET hydrolysate containing ethylene glycol; and mixing the treating fluid and the PET hydrolysate to prepare an electrolyte, and converting ethylene glycol and sulfur-containing oxides in the PET hydrolysate into hydroxyl methane sulfonate through an electrolytic reaction. According to the method, industrial sulfur-containing flue gas treatment and waste PET plastic recycling are cooperated, sulfur-containing flue gas and waste PET plastic are combined, upgraded and converted into high-value chemical hydroxymethane sulfonate, the recycling value of the waste PET plastic is increased, meanwhile, products in the industrial flue gas desulfurization process are fully utilized, and the utilization rate and economic benefits of waste circulation are increased.

Description

Technical Field

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

[0002] In the process of non-ferrous smelting and processing, industrial flue gas is an inevitable by-product, among which industrial sulfur-containing flue gas is regarded as polluting waste gas because it contains a large amount of sulfur oxides. The sulfur oxides it contains are typically sulfur dioxide, which is one of the main gases causing acid rain. If it is not safely disposed of, it will usually cause corrosion and damage to soil, water bodies, vegetation, and buildings. Therefore, the recovery of industrial sulfur-containing flue gas can not only effectively reduce environmental pollution in industrial production, but also is an important way to achieve resource disposal of harmful gases.

[0003] In recent years, the treatment technology of industrial sulfur-containing flue gas has mainly focused on desulfurization to meet emission standards, while converting the sulfur element in it into chemical substances such as sulfuric acid and sulfate. Wet absorption is one of the main technologies for flue gas desulfurization. Its main principle is to absorb SO2 in sulfur-containing flue gas with alkaline solution to obtain a mixed solution containing sulfur oxides.

[0004] Chinese patent CN201711452293.7 discloses a method for preparing sulfuric acid from smelting flue gas. The method involves drying the deeply purified sulfur-containing flue gas in dilute sulfuric acid, and then sending the dried sulfur-containing flue gas into a converter containing a catalyst bed to convert sulfur dioxide in the flue gas into sulfur trioxide. Finally, the flue gas is passed into sulfuric acid to generate concentrated sulfuric acid. The method is simple in process, easy to operate, and has strong process universality, but its final product is relatively conventional, has high requirements for equipment, 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 into a fly ash pickling salt solution after heat exchange treatment and oxidation treatment, and then obtains washed calcium sulfate and washing liquid through separation, precipitation, and water washing treatment. The washing liquid is mixed with the mother liquor in the first part and then evaporated to obtain a saturated salt solution and 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 always been a hot topic of global concern. Traditional methods of treating waste PET plastics, such as incineration and landfilling, occupy a large amount of land resources and cause serious harm to soil, water and atmosphere. In recent years, electrocatalytic technology has gradually shown its potential in the reuse of waste PET plastics. It can achieve the upgrading and conversion of waste PET plastics into terephthalic acid (PTA) and ethylene glycol (EG) monomers with high efficiency and selectivity. The final products of this process are often formic acid and glycolic acid. Although they have certain economic benefits, the development of higher value products is the development trend of electrocatalytic waste PET plastic research.

[0007] Based on this, the present invention proposes a new method for synergistically treating industrial sulfur-containing flue gas and waste PET plastics, aiming to achieve safe disposal of solid waste and short-process preparation of high-value chemicals. The process first treats industrial sulfur-containing flue gas by wet absorption and waste PET plastics by alkaline hydrolysis, and then further couples sulfur oxides with carbon atoms by electrocatalysis to form hydroxymethane sulfonates. Hydroxymethane sulfonates, as an important compound, are widely used as intermediates in drug synthesis, such as playing a key role in the synthesis of drugs such as isoniazid sodium sulfonate and cancer enemy, and therefore occupy an important position in the pharmaceutical industry.

[0008] Under the guidance of the green and sustainable development of the world's economic and social development, the rational disposal of solid waste and industrial waste gas is crucial to the construction of a green, low-carbon, circular development economic system. Based on this, the present invention not only combines the recycling of waste plastic PET with the treatment of industrial sulfur-containing flue gas, but also proposes a short-process process for preparing high-value chemicals, which can not only effectively solve the environmental problems caused by industrial sulfur-containing flue gas and plastic waste, but also has high economic benefits, thereby promoting the development of the 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 and upgrade 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 at the same time making full use of the products of the industrial flue gas desulfurization process to improve the utilization rate and economic benefits of waste recycling.

[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 to upgrade and convert them 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 solution, wherein the sulfur-containing flue gas contains sulfur oxides;

[0013] S2. The waste PET plastic is hydrolyzed in an alkali 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 electrolytic 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 of the step S3 is a constant voltage condition, and the voltage is 1.20 to 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 by an electrocatalytic method, while producing high-value chemical products, upgrading the traditional industrial sulfur-containing flue gas treatment process, rationally utilizing the waste liquid generated in the desulfurization process, and preparing hydroxymethane sulfonate in a short process. The present invention simultaneously realizes the efficient treatment of sulfur-containing flue gas and the efficient recycling of waste PET plastics, and has 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 undergoes hydrolysis reaction 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 electrocatalyzed and synthesized by an electrochemical method, and a CS coupling reaction is performed 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 a specific metal oxide or metal hydroxide as a catalyst to make a working electrode, and select suitable 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 the potential for industrial production and broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Flow chart of the method of the present invention.

[0027] Figure 2 This is a 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 electrolytic system of Example 1.

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

[0031] Figure 6 is 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 hydroxymethane sulfonate yield test result of Comparative Example 2 is shown in FIG. DETAILED DESCRIPTION

[0034] The present invention is further described in detail below by way of examples to illustrate the features and advantages of the present invention, but not to 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 to upgrade them 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 solution, wherein the sulfur-containing flue gas contains sulfur oxides;

[0037] S2. The waste PET plastic is hydrolyzed in an alkali 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 electrolytic reaction converts the ethylene glycol and sulfur-containing oxides in the PET hydrolyzate into hydroxymethane sulfonate.

[0039] The method of the 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 under alkaline conditions on waste PET plastics and then adjusting the pH to obtain a PET hydrolyzate containing ethylene glycol; introducing the treated liquid, adjusting the pH and using it as an electrolyte, electrolyzing it under an electrode system, and performing a CS coupling reaction to realize upgrading and converting the ethylene glycol in the PET alkaline hydrolyzate into hydroxymethane sulfonate.

[0040] Therefore, the present invention combines and upgrades the sulfur-containing flue gas and waste PET plastics into high-value chemical hydroxymethane sulfonate by coordinating industrial sulfur-containing flue gas treatment, waste PET plastic recycling technology and electrochemical methods, thereby improving the recycling value of 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 waste recycling.

[0041] In the present invention, the industrial sulfur-containing flue gas in step S1 contains SO2 gas. The flue gas containing SO2 mainly comes from the following types of combustion or industrial processing processes: coal combustion, oil combustion, natural gas combustion, sulfide ore roasting, production of carbon disulfide (CS2) or production of sulfite (such as pulp bleaching process), etc.

[0042] Preferably, the alkali solution is 0.1-4 mol / L NaOH or KOH solution, the introduction rate of the sulfur-containing flue gas is 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 blocks or processed waste PET plastic products. The processed waste PET plastic products may be waste products such as packaging bottles, packaging boxes, and films. The processed waste PET plastic products may be crushed to obtain PET powder or sheared to obtain waste PET plastic blocks.

[0045] 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, solid-liquid ratio of 1:5-1:20 (g / mL); the concentration of the alkaline solution and the reaction conditions can be appropriately adjusted according to different waste PET plastics for hydrolysis reaction. For example, for powdered PET plastics, within the optional parameter range of step S2, the hydrolysis reaction of PET can be achieved with a relatively low concentration of alkaline solution, a relatively low temperature, a relatively fast reaction time and a small amount of solution.

[0046] 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.

[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 sulfates and chlorides.

[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 and can stably load the metal catalyst on its surface. In order to achieve effective loading of metal oxides or hydroxides, the carrier can be pretreated by some conventional surface pretreatment methods such as water washing, alcohol cleaning, acid washing, alkali washing or grinding.

[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 load 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; the metal hydroxide is preferably cobalt hydroxide, nickel hydroxide, copper hydroxide, manganese hydroxide or palladium hydroxide.

[0056] Preferably, the electrolysis condition of the step S3 is a constant voltage condition, and the voltage is 1.20 to 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 in conjunction with specific implementation methods.

[0058] Example 1

[0059] This embodiment provides the following method for electrocatalytically co-processing industrial sulfur-containing flue gas and PET waste plastics to upgrade them 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 from the roasting of sulfide ore, the sulfur oxide in the flue gas is SO2 gas, the alkali solution used to capture the SO2 gas includes 0.1mol / L NaOH solution, the flow rate of the sulfur-containing flue gas is 5ml / s, the introduction time is 30min, and a treated liquid is obtained, which contains sulfite.

[0062] S2. Waste PET plastic is hydrolyzed under alkaline conditions to obtain PET hydrolyzate containing ethylene glycol.

[0063] The waste PET plastic is 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, and the solid-liquid ratio is 1:20.

[0064] The waste PET plastic is hydrolyzed with an alkaline solution and the hydrolyzate is adjusted to pH=2.8. After solid-liquid separation of the precipitated TPA, an acidic hydrolyzate containing ethylene glycol is obtained.

[0065] S3. The treated liquid and the PET hydrolyzate are mixed to prepare an electrolyte, and the electrolytic reaction converts the ethylene glycol and sulfur-containing oxides in the PET hydrolyzate into hydroxymethane sulfonate.

[0066] 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.

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

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

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

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

[0071] 3) Drying and calcining: The washed carbon cloth is placed in an oven and dried at 60°C to a constant weight. Then, it is placed in a tube furnace and calcined at 300°C for 2 hours and cooled naturally to obtain manganese dioxide supported by 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 0.1M K2SO4, 20mM NaSO3 and 200mM ethylene glycol. The voltage was 1.35V vs.Ag / AgCl and the reaction time was 240min.

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

[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 is a linear sweep voltammetry (LSV) curve collected in the electrolytic system of this embodiment. It can be seen that the initial oxidation potential of the electrolytic system of this embodiment is 0.425V; the curve marked with oxygen evolution reaction is obtained in an electrolyte containing only the same concentration of sulfite and no ethylene glycol, and the same electrode system is used as in 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 to upgrade them 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 for capturing the SO2 gas includes 1 mol / L NaOH solution, the flow rate of the sulfur-containing flue gas is 4 ml / s, the introduction 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 PET hydrolyzate containing ethylene glycol.

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

[0084] The waste PET plastic is hydrolyzed with an alkaline solution, and 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 electrolytic 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 adopts a three-electrode system, which consists 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 electrolytic 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 and mix.

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

[0091] 3) Drying: The 1 cm*1 cm carbon cloth was vacuum dried at 60° C. for 4 hours to obtain nickel hydroxide supported by 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 hydroxymethane sulfonate (HMS), in which dimethyl sulfoxide (DMSO) is a solvent added for testing. The solution after the electrolysis reaction was analyzed and the yield of hydroxymethane sulfonate was 0.26 mol cm - 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 to upgrade them 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 alkali solution used to capture the SO2 gas includes 2mol / L NaOH solution, the flow rate of the sulfur-containing flue gas is 3ml / s, the introduction time is 20min, and an aqueous solution of sulfur oxides is obtained.

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

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

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

[0101] The waste PET plastic is hydrolyzed with an alkaline solution and 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 electrolytic 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 adopts a three-electrode system, which consists 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, keep it at 50°C in a constant temperature water bath and stir for 24 hours to ensure that the copper nitrate is fully adsorbed on the surface of the carbon fiber paper. Take out the impregnated carbon fiber paper and rinse it with deionized water to remove the copper nitrate that is not adsorbed on the surface. Put the carbon fiber paper loaded with copper nitrate into an oven and dry it at 60°C to constant weight.

[0108] 3) Drying and calcining: 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 the calcination, the carbon fiber paper is taken out and placed in an oven again at 60°C to dry to constant weight. Copper oxide supported by the carbon fiber paper is obtained.

[0109] The electrolytic 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. The solution after the electrolytic reaction was analyzed and the yield of hydroxymethane sulfonate was 0.23 mol cm -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 to upgrade them 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 oxide in the flue gas is SO2 gas, the alkali solution used for capturing the SO2 gas includes a 3mol / L NaOH solution, the flow rate of the sulfur-containing flue gas is 2ml / s, the introduction time is 50min, and a treated liquid is obtained, which contains sulfite.

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

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

[0116] The specific operation of pH adjustment treatment is to adjust the pH of the waste PET plastic to 3.0 after hydrolysis with alkaline solution, separate the precipitated TPA from the solid and liquid, and obtain an acidic hydrolyzate containing ethylene glycol; adjust the pH of the acidic hydrolyzate to 5.65 for subsequent electrolysis reaction. The PET alkaline hydrolyzate is subjected to nuclear magnetic resonance detection after pH adjustment and separation. 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 electrolytic 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 adopts a three-electrode system, which consists 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 1cm*1cm carbon fiber paper in copper sulfate deposition solution, and use magnetic stirring to evenly distribute the solution on the surface of the carbon fiber paper for 30 minutes to ensure that the copper ions are fully adsorbed. Take out the carbon fiber paper impregnated with copper sulfate, drain the excess solution, and then quickly immerse it in sodium hydroxide solution. At this time, copper hydroxide precipitation reaction will occur on the surface of the carbon fiber paper. Keep it for 10 minutes and stir to promote uniform reaction.

[0123] 3) Drying: After the reaction is completed, the carbon fiber paper is taken out and rinsed 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 and dried at 60°C to constant weight to remove excess water to obtain copper hydroxide loaded on the carbon fiber paper.

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

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

[0126] Example 5

[0127] This embodiment provides the following method for electrocatalytically co-processing industrial sulfur-containing flue gas and PET waste plastics to upgrade them into hydroxymethane sulfonate, comprising:

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

[0129] The industrial sulfur-containing flue gas is the flue gas from the roasting of sulfide ore, the sulfur oxide in the flue gas is SO2 gas, the alkali solution used to capture the SO2 gas includes 4mol / L NaOH solution, the flow rate of the sulfur-containing flue gas is 4ml / s, the introduction time is 10min, and a treated liquid is obtained, which contains sulfite.

[0130] S2. Waste PET plastic is hydrolyzed under alkaline conditions to obtain PET hydrolyzate containing ethylene glycol.

[0131] The waste PET plastic is 200 mesh waste PET powder, the alkaline solution for treating the waste PET plastic 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 specific operation of pH adjustment treatment is to hydrolyze the waste PET plastic with an alkaline solution and adjust the hydrolyzate to pH=2.9, and after solid-liquid separation of the precipitated TPA, obtain an acidic hydrolyzate containing ethylene glycol.

[0133] S3. The treated liquid and the PET hydrolyzate are mixed to prepare an electrolyte, and the electrolytic reaction converts the ethylene glycol and sulfur-containing oxides in the PET hydrolyzate into hydroxymethane sulfonate.

[0134] 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.

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

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

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

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

[0139] 3) Drying and calcining: The carbon fiber paper loaded with cobalt nitrate is placed in an oven and dried at 60°C to constant weight. The dried carbon fiber paper is placed in a muffle furnace and calcined at 500°C for 4 hours to decompose the cobalt nitrate and convert it into cobalt oxide. After the calcination, the carbon fiber paper is taken out and placed in an oven again at 60°C to dry to constant weight to obtain cobalt oxide loaded on the carbon fiber paper.

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

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

[0142] Example 6

[0143] This embodiment provides the following method for electrocatalytically co-processing industrial sulfur-containing flue gas and PET waste plastics to upgrade them into hydroxymethane sulfonate, comprising:

[0144] S1. Passing industrial sulfur-containing flue gas into alkaline solution to obtain a treated liquid, wherein the sulfur-containing flue gas contains sulfur oxides.

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

[0146] S2. Waste PET plastic is hydrolyzed under alkaline conditions to obtain PET hydrolyzate containing ethylene glycol.

[0147] The waste PET plastic is 200 mesh waste PET powder, the alkaline solution for treating the waste PET plastic is 4 mol / L NaOH solution, the reaction temperature is 90°C, the stirring speed is 400 rpm, the reaction time is 8 hours, and the solid-liquid ratio is 1:10.

[0148] The specific operation of the pH adjustment treatment is to hydrolyze the waste PET plastic with an alkaline solution and adjust the hydrolyzate to pH = 2.8, and after solid-liquid separation of the precipitated TPA, obtain an acidic hydrolyzate containing ethylene glycol.

[0149] S3. The treated liquid and the PET hydrolyzate are mixed to prepare an electrolyte, and the electrolytic reaction converts the ethylene glycol and sulfur-containing oxides in the PET hydrolyzate into hydroxymethane sulfonate.

[0150] 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.

[0151] The electrolysis reaction adopts a three-electrode system, which consists of a working electrode, a counter electrode and a reference electrode. The working electrode is palladium oxide supported 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 for the electrolysis reaction is as follows:

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

[0154] 2) Chemical deposition: Immerse a 1cm*1cm carbon cloth in the deposition solution, making sure 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 to 75°C. After reacting for 6 hours, take out the carbon cloth and rinse it with deionized water to remove the unreacted substances attached to the surface.

[0155] 3) Drying and calcining: Put the washed carbon cloth into an oven and dry it at 60°C to constant weight. Then place it in a tube furnace and calcine it at 300°C for 2 hours, and cool it naturally. Then place it in a tube furnace and calcine it at 500°C for 3 hours to remove impurities, and cool it naturally to remove the palladium oxide loaded on the carbon cloth.

[0156] The electrolytic reaction voltage was 1.35 V vs. Ag / AgCl, the electrolyte used contained 0.1 M K2SO4, 20 mM NaSO3, 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] Different from Example 1, the working electrode used in step S3 is changed to Au / Ni(OH)2 loaded with nickel foam.

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

[0161] First, a 1cm*1cm nickel foam electrode was immersed in a mixed solution of 0.05mM AuCl3 and 0.5M NaCl and placed at 25°C for 6 hours. Then, the pre-product was washed with ultrapure water and ethanol. Finally, the nickel foam was annealed in an oven at 200°C for 2 hours to prepare an Au / Ni(OH)2 composite catalyst supported on nickel foam. Among them, Ni(OH)2 is a porous material layer on the surface of the nickel foam electrode, which is covered with a layer of metal Au as a carrier surface.

[0162] The electrolyte used contained 0.1M K2SO4, 20mM NaSO3, and 200mM ethylene glycol, and the collected linear sweep voltammetry (LSV) curve test, such as Figure 7 The mark shown has the test results of EG+SO3, while Figure 7 The curve marked with oxygen evolution reaction is used as a reference. It is obtained by linear sweep voltammetry test under the same electrode conditions as in this comparative example, but the electrolyte does not contain ethylene glycol but only contains the same concentration of sulfite. It can be seen that the working electrode of this comparative example cannot catalyze the electrolytic reaction to obtain hydroxymethane sulfonate. It can be seen that the metal hydroxide or oxide loaded on the working electrode proposed by the present invention can effectively realize the electrocatalytic synergistic treatment of industrial sulfur-containing flue gas and PET waste plastics to upgrade 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, and the pH values ​​are: 5.3, 5.4, 5.5, 5.6, 5.7, 5.8 and 5.9.

[0165] The yield of hydroxymethane sulfonate 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 implementation modes of the present invention, but the implementation modes 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 equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A method for electrocatalytically co-treatment of industrial sulfur-containing flue gas and PET waste plastics to upgrade them into hydroxymethane sulfonate, characterized in that: The following steps are involved: S1. Passing industrial sulfur-containing flue gas into an alkaline solution to obtain a treatment solution, wherein the sulfur-containing flue gas contains sulfur oxides; S2. The waste PET plastic is hydrolyzed in an alkali solution to obtain a PET hydrolyzate containing ethylene glycol; S3. The treated liquid and the PET hydrolyzate are mixed to prepare an electrolyte, and the electrolytic reaction converts the ethylene glycol and sulfur-containing oxides in the PET hydrolyzate into hydroxymethane sulfonate.

2. A method for electrocatalytically co-processing industrial sulfur-containing flue gas and PET waste plastics to upgrade them 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 0.1-4 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 SO2 gas is converted into sulfite.

3. A method for electrocatalytically co-processing industrial sulfur-containing flue gas and PET waste plastics to upgrade them into hydroxymethane sulfonate according to claim 1, characterized in that: The hydrolysis conditions of the S2 step 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 to upgrade them 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 waste PET plastic processed products.

5. A method for electrocatalytically co-processing industrial sulfur-containing flue gas and PET waste plastics to upgrade them into hydroxymethane sulfonate according to claim 1, characterized in that: In the 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.

6. A method for electrocatalytically co-processing industrial sulfur-containing flue gas and PET waste plastics to upgrade them into hydroxymethane sulfonate according to claim 1, characterized in that: The electrode system of step S3 consists of a working electrode, a counter electrode and a reference electrode; preferably, 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; preferably, the metal of the working electrode includes: one or more of cobalt, nickel, manganese, copper or palladium.

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

8. A method for electrocatalytically co-processing industrial sulfur-containing flue gas and PET waste plastics to upgrade them into hydroxymethane sulfonate according to claim 1, characterized in that: The pH value of the electrolyte in step S3 is 5.6-5.

7.

9. A method for electrocatalytically co-processing industrial sulfur-containing flue gas and PET waste plastics to upgrade them 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.

Images