Method for preparing photocatalyst from coal chemical industry coked sulfur paste, photocatalyst and application of photocatalyst

Abstract

The invention discloses a method for preparing a photocatalyst from coal chemical coking sulfur paste, the photocatalyst and application of the photocatalyst, and belongs to the technical field of catalyst preparation. According to the method, wet coked sulfur paste generated by HPF wet oxidation desulfurization is adopted as a raw material, and solid waste coked sulfur paste which is difficult to treat is converted into the alpha-S photocatalyst with photocatalytic activity through water washing extraction, NaOH thermal dissolution, surfactant modification, acetic acid acidification, standing aging, ethanol washing extraction and drying treatment, so that high-quality utilization of treating waste with waste is realized. The obtained alpha-S photocatalyst can effectively catalyze and degrade rhodamine B under visible light, compared with sulfur (analytically pure) and coked sulfur paste which is washed and dried, the degradation efficiency is improved by about 40% and 60% respectively, and the rhodamine B degradation effect is remarkable.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalyst preparation, and in particular, relates to a method for preparing a photocatalyst from coking sulfur paste, a solid waste of coal chemical industry, and a photocatalyst obtained by the method and application thereof. Background Art

[0002] In the process of removing H2S from coke oven gas by HPF wet oxidation method, a kind of industrial solid waste, coking sulfur paste, which has high production, is difficult to utilize and highly polluting, will be produced. Its main component is sulfur, and its impurities include water-soluble impurities (secondary salts such as ammonium thiocyanate and ammonium thiosulfate, desulfurization catalyst), dichlorotoluene soluble impurities (coal tar organic matter) and other impurities (coal powder, etc.). Among them, the coal tar organic matter is similar to the eight-membered ring structure of sulfur, which makes it difficult to purify and utilize. Therefore, how to effectively treat coking sulfur paste has become a technical problem that needs to be solved urgently by coking enterprises.

[0003] At present, most coking enterprises mainly treat coking sulfur paste by sulfur melting method and incineration acid production method. The sulfur melting method is a traditional method for recovering and purifying sulfur from coking sulfur paste. The sulfur melting kettle is used to melt sulfur by steam heating, and the sulfur in the coking sulfur paste is purified by using the difference in melting point and density between sulfur and other impurities and the principle of gravity sedimentation. However, this technology has problems such as high energy consumption, serious secondary pollution, and poor quality of sulfur products, and the sulfur melting technology needs to be improved. The incineration acid production method includes pretreatment of raw materials, incineration, recovery and preheating, purification, drying, conversion, absorption and tail gas treatment processes. Generally, coking enterprises will treat desulfurization waste liquid and coking sulfur paste together for acid production to produce 98% sulfuric acid products. Chen Miao and others used oxygen enrichment combustion high-temperature cracking and two-transformation and two-absorption drying methods to make sulfuric acid products from coking sulfur paste and desulfurization waste liquid, which has been successfully applied to the 30kt / a sulfur paste and desulfurization waste liquid acid production project of Tiexiong Metallurgical. However, since coking sulfur paste and desulfurization waste liquid contain a lot of impurities, they are easy to absorb moisture and form lumps, causing blockage of the incinerator and high maintenance costs.

[0004] The main component of coking sulfur paste is sulfur. Liu Gang et al. found that elemental sulfur has the ability to convert OH into - The ability to oxidize into OH radicals is a highly stable semiconductor photocatalyst. Therefore, the application of coke sulfur paste in the field of photocatalytic degradation of pollutants can reduce the cost of photocatalysts while achieving resource processing and high-quality utilization of coke sulfur paste. Summary of the invention

[0005] The purpose of the present invention is to provide a method for preparing a photocatalyst from coking sulfur paste in coal chemical industry, a photocatalyst and its application, so as to overcome the defects of the existing coking sulfur paste processing technology, such as high energy consumption and difficult sulfur purification, and to prepare α-S with photocatalytic activity.

[0006] To achieve the above object, according to one aspect of the present invention, a method for preparing a photocatalyst from coking sulfur paste in coal chemical industry is provided, comprising: Step 1: Wash the coked sulfur paste produced by the HPF wet oxidation desulfurization process with water, obtain a filtrate and a filter residue after solid-liquid separation, and use the filtrate to prepare the desulfurization liquid; Step 2: The filter residue with sulfur as the main component obtained in step 1 is evaporatively dried and then crushed to a particle size of 5-10 μm, and then fed into a sulfur dissolving reactor with a sodium hydroxide solution having a mass concentration of 10%-20%, and reacted at a temperature of 90°C-95°C to generate sodium polysulfide until the sulfur is completely dissolved, and then filtered to obtain the filter residue and the filtrate containing sodium polysulfide, and the filter residue is fed into a coal pile for coal blending and coking; the chemical reaction formula involved is as follows: ; Step 3, feeding the filtrate containing sodium polysulfide obtained in step 2 into a mixer, and adding a surfactant solution to obtain a uniformly mixed solution; Step 4: add excess acetic acid containing a surfactant to the acidification treatment device, then dropwise add the mixed solution obtained in step 3 to the acidification treatment device, continue the reaction for 1 to 2 hours after the addition is completed, and send the gas at the top of the acidification reactor to the raw gas for purification; the chemical reaction formula involved is as follows: ; Step 5, sending the material obtained after the reaction in step 4 into an aging kettle, separating the filtrate and the precipitate after standing and aging, and sending the filtrate into the regulating tank of the enterprise's biochemical treatment system; Step 6, sending the precipitate obtained in step 5 and industrial ethanol into an elution device at a liquid-to-solid ratio of 5-10 L / kg, performing solid-liquid separation after elution to obtain a filtrate and a filter residue, and recovering ethanol from the filtrate by distillation for recycling; Step seven, drying the filter residue obtained in step six, and the obtained product is α-S with photocatalytic activity.

[0007] As a preferred embodiment, in step 1, the coked sulfur paste produced by the HPF wet oxidation desulfurization method refers to the sulfur paste obtained by filtering or centrifuging sulfur foam, and has a sulfur content of 70% to 80%.

[0008] As a preferred embodiment, in step 1, the coked sulfur paste and water are sent to a water washing device at a liquid-to-solid ratio of 10-20 L / kg for multiple water washings.

[0009] As a preferred embodiment, in step three, the surfactant refers to a non-ionic polymer that can serve as a template and surface modifier, including at least one of the following surfactants: polyvinyl pyrrolidone PVP-K15, polyvinyl pyrrolidone PVP-K30, octylphenol polyoxyethylene ether OP-10, polyethylene glycol octylphenyl ether TX-100, and polyvinyl alcohol PVA-1788.

[0010] As a preferred embodiment, in step three, the sodium polysulfide filtrate and the surfactant are mixed in a mixer at a rotation speed of 20 to 50 rmp.

[0011] As a preferred embodiment, in step three, the amount of the surfactant solution added is 5 to 10 times the volume of the filtrate fed into the mixer, and the concentration is 1 g / L to 2 g / L.

[0012] As a preferred embodiment, the surfactant in step 4 is the same as the surfactant in step 3 and has the same effect and concentration.

[0013] As a preferred embodiment, in step seven, the filter residue is dried by evaporation at 40-50°C.

[0014] According to another aspect of the present invention, a photocatalyst is provided, which is α-S having photocatalytic activity obtained by any one of the above methods.

[0015] According to another aspect of the present invention, provided is the use of the above-mentioned photocatalyst in catalytic degradation of organic pollutants.

[0016] The beneficial effects of the present invention are as follows: The present invention uses wet coke sulfur paste produced by desulfurization using the HPF wet oxidation method as raw material, and converts the difficult-to-treat solid waste coke sulfur paste into an α-S photocatalyst with photocatalytic activity through water elution, NaOH thermal dissolution, surfactant modification, acetic acid acidification, static aging, ethanol elution and drying treatment, thereby achieving high-quality utilization of waste for waste treatment.

[0017] The α-S photocatalyst obtained by the present invention can effectively catalyze the degradation of Rhodamine B under visible light, dissolve in NaOH with a mass concentration of 20%, and the α-S photocatalyst prepared with PVP-K15 as a surfactant has a degradation rate of 95% when irradiated under 420nm visible light for 210min, which is increased by about 40% and 60% respectively compared with sulfur (analytical grade) and coked sulfur paste washed and dried, and has a significant effect in degrading Rhodamine B.

[0018] The photocatalyst of the present invention is applied to the degradation of organic pollutants. Compared with other photocatalysts, it has the advantages of being abundant, cheap, non-toxic, highly stable, and highly recyclable, and has the prospect of being widely promoted and applied in the field of photocatalytic engineering. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The process flow chart of the method of the present invention is shown in FIG.

[0020] Figure 2 The figure shows the relationship between the efficiency and time of photocatalytic degradation of Rhodamine B under visible light irradiation in Comparative Examples 1-2 and Examples 1-4 of the present invention. DETAILED DESCRIPTION

[0021] The technical scheme claimed in the present invention is further described below by some examples. However, the examples are used to explain the embodiments of the present invention and do not exceed the scope of the subject matter of the present invention. The protection scope of the present invention is not limited by the examples. Unless otherwise specified, the materials and reagents used in the present invention can be obtained from commercial products in the art.

[0022] The coking sulfur paste treated in the following examples is obtained by filtering or centrifuging the sulfur foam produced by desulfurization using the HPF wet oxidation method in a coking plant. The sulfur paste contains 72% sulfur, 11% water, 10.8% water-soluble salts, 3.7% tars, and 2.32% other impurities. Example 1

[0023] S1. Water washing: 1 kg of coking sulfur paste and 10 L of water are sent to the water washing device. After elution 3 times, solid-liquid separation is performed by filtration or centrifugation. The filtrate is used for the preparation of desulfurization liquid.

[0024] S2. Dissolution: The filter residue obtained from the solid-liquid separation of S1 is evaporated and dried to obtain about 0.78 kg of dry sulfur paste. The dry sulfur paste is crushed into a particle size of 5-10 μm using a special sulfur crusher and sent to a sulfur dissolving reactor. At the same time, 4.5 L of 20% by mass sodium hydroxide solution is added. The reaction is carried out at a temperature of 90°C until the sulfur is completely dissolved, and the filter residue is sent to the coal pile for coal blending and coking.

[0025] S3. Mixing: The filtrate of S2 was sent to a mixer, and 45 L of 1 g / L polyvinylpyrrolidone PVP-K15 solution was added, and mixed at a speed of 50 rpm to obtain a uniform mixed solution.

[0026] S4. Acidification: Add 45 L of 2 mol / L acetic acid containing 1 g / L polyvinylpyrrolidone PVP-K15 to the acidification processor. After mixing evenly with a stirrer, slowly add the mixed solution of S3 to the acidification processor. After the addition is completed, continue the reaction for 2 hours, and the top gas is sent to the raw gas purification.

[0027] S5. Aging: The material after the S4 reaction is sent to the aging kettle. After standing and aging for 5 hours, it is filtered or centrifuged to obtain the filtrate and precipitate. The filtrate is sent to the regulating tank of the enterprise's biochemical treatment system.

[0028] S6. Elution: The precipitate of S5 and industrial ethanol are sent to the elution device at a liquid-to-solid ratio of 5 L / kg. After elution, the solid-liquid separation is carried out by filtration or centrifugation, and the filtrate is distilled to recover the ethanol for recycling.

[0029] S7. Drying: The filter residue of S6 was evaporated to dryness at 45°C in an evaporative dryer. The obtained product α-S was a light yellow-green powder with a mass of about 0.36 kg. Example 2

[0030] S1. Water washing: 1 kg of coking sulfur paste and 15 L of water are sent to the water washing device. After elution twice, solid-liquid separation is performed by filtration or centrifugation. The filtrate is used for the preparation of desulfurization liquid.

[0031] S2. Dissolution: The filter residue obtained from the solid-liquid separation of S1 is evaporated and dried to obtain about 0.78 kg of dry sulfur paste. The dry sulfur paste is crushed into a particle size of 5-10 μm using a special sulfur crusher and sent to a sulfur dissolving reactor. At the same time, 4.5 L of 10% by mass sodium hydroxide solution is added. The reaction is carried out at a temperature of 95°C until the sulfur is completely dissolved, and the filter residue is sent to the coal pile for coal blending and coking.

[0032] S3. Mixing: The filtrate of S2 was sent to a mixer, and 22.5 L of 2 g / L polyvinylpyrrolidone PVP-K15 solution was added, and mixed at a speed of 50 rpm to obtain a uniform mixed solution.

[0033] S4. Acidification: Add 22.5 L of 2 mol / L acetic acid containing 2 g / L polyvinylpyrrolidone PVP-K15 to the acidification processor. After mixing evenly with a stirrer, slowly add the mixed solution of S3 to the acidification processor. After the addition is completed, continue the reaction for 1 hour, and the top gas is sent to the raw gas purification.

[0034] S5. Aging: The material after S4 reaction is sent to the aging kettle. After standing and aging for 5 hours, the filtrate and precipitate are obtained by filtration or centrifugal separation. The filtrate is sent to the regulating tank of the enterprise's biochemical treatment system.

[0035] S6. Elution: The precipitate of S5 and industrial ethanol are sent to the elution device at a liquid-to-solid ratio of 10 L / kg. After elution, the solid-liquid separation is carried out by filtration or centrifugation, and the filtrate is distilled to recover the ethanol for recycling.

[0036] S7. Drying: The filter residue of S6 was evaporated to dryness at 40°C in an evaporative dryer. The obtained product α-S was a light yellow-green powder with a mass of about 0.36 kg. Example 3

[0037] S1. Water washing: 1 kg of coking sulfur paste and 10 L of water are sent to the water washing device. After elution 3 times, solid-liquid separation is performed by filtration or centrifugation. The filtrate is used for the preparation of desulfurization liquid.

[0038] S2. Dissolution: The filter residue obtained from the solid-liquid separation of S1 is evaporated and dried to obtain about 0.78 kg of dry sulfur paste. The dry sulfur paste is crushed into a particle size of 5-10 μm using a special sulfur crusher and sent to a sulfur dissolving reactor. At the same time, 5 L of 10% sodium hydroxide solution is added. The reaction is carried out at a temperature of 95°C until the sulfur is completely dissolved, and the filter residue is sent to the coal pile for coal blending and coking.

[0039] S3. Mixing: The filtrate of S2 is sent to a mixer, and 50 L of 1 g / L octylphenol polyoxyethylene ether OP-10 solution is added, and mixed at a speed of 50 rpm to obtain a uniform mixed solution.

[0040] S4. Acidification: Add 50 L of 2 mol / L acetic acid containing 1 g / L octylphenol polyoxyethylene ether OP-10 to the acidification processor. After mixing evenly with a stirrer, slowly add the mixed solution of S3 to the acidification processor. After the addition is completed, continue the reaction for 2 hours, and the top gas is sent to the raw gas purification.

[0041] S5. Aging: The material after S4 reaction is sent to the aging kettle. After standing and aging for 5 hours, the filtrate and precipitate are obtained by filtration or centrifugal separation. The filtrate is sent to the regulating tank of the enterprise's biochemical treatment system.

[0042] S6. Elution: The precipitate of S5 and industrial ethanol are sent to the elution device at a liquid-to-solid ratio of 7 L / kg. After elution, the solid-liquid separation is carried out by filtration or centrifugation, and the filtrate is distilled to recover the ethanol for recycling.

[0043] S7. Drying: The filter residue of S6 was evaporated to dryness at 50°C in an evaporative dryer. The obtained product α-S was a light yellow-green powder with a mass of about 0.36 kg. Example 4

[0044] S1. Water washing: send 1 kg of coking sulfur paste and 20 L of water into the water washing device. After elution once, filter or centrifuge to separate the solid and liquid. The filtrate is used for the preparation of desulfurization liquid.

[0045] S2. Dissolution: The filter residue obtained from the solid-liquid separation of S1 is evaporated and dried to obtain about 0.78 kg of dry sulfur paste. The dry sulfur paste is crushed into a particle size of 5-10 μm using a special sulfur crusher and sent to a sulfur dissolving reactor. At the same time, 4 L of 20% sodium hydroxide solution is added. The reaction is carried out at a temperature of 92°C until the sulfur is completely dissolved, and the filter residue is sent to the coal pile for coal blending and coking.

[0046] S3. Mixing: The filtrate of S2 was sent to a mixer, and 32 L of 1.5 g / L octylphenol polyoxyethylene ether OP-10 solution was added, and mixed at a speed of 50 rpm to obtain a uniform mixed solution.

[0047] S4. Acidification: Add 32 L of 2 mol / L acetic acid containing 1.5 g / L octylphenol polyoxyethylene ether OP-10 to the acidification processor. After mixing evenly with a stirrer, slowly add the mixed solution of S3 to the acidification processor. After the addition is completed, continue the reaction for 1 hour, and the top gas is sent to the raw gas purification.

[0048] S5. Aging: The material after S4 reaction is sent to the aging kettle. After standing and aging for 5 hours, the filtrate and precipitate are obtained by filtration or centrifugal separation. The filtrate is sent to the regulating tank of the enterprise's biochemical treatment system.

[0049] S6. Elution: The precipitate of S5 and industrial ethanol are sent to the elution device at a liquid-to-solid ratio of 7 L / kg. After elution, the solid-liquid separation is carried out by filtration or centrifugation, and the filtrate is distilled to recover the ethanol for recycling.

[0050] S7. Drying: The filter residue of S6 was evaporated to dryness at 40°C in an evaporative dryer. The obtained product α-S was a light yellow-green powder with a mass of about 0.36 kg.

[0051] Comparative Example 1 Sulfur (AR analytical grade).

[0052] Comparative Example 2 1 kg of coking sulfur paste and 10 L of water were sent to the washing device. After elution 3 times, solid-liquid separation was performed by filtration or centrifugation. The filter residue obtained by separation was evaporated and dried to obtain about 0.78 kg of dry sulfur paste. The dry sulfur paste was crushed to a particle size of 5-10 μm using a special sulfur crusher.

[0053] Photocatalytic performance test: The performance test of the above-obtained pale yellow-green powder photocatalyst, sulfur and water-washed coking sulfur paste in degrading Rhodamine B was carried out: At room temperature, 0.3 g of the catalyst samples obtained in Comparative Example 1, Comparative Example 2, Example 1, Example 2, Example 3 and Example 4 were weighed respectively, and dispersed in 150 mL of a 50 mg / L Rhodamine B solution (Rhodamine B, AR, Changde Beekman Biotechnology Co., Ltd.) using magnetic stirring, and dark-treated for 60 min to allow the system to reach adsorption-desorption equilibrium. A 300W xenon lamp with a 420 nm cutoff filter was used as the visible light source to illuminate the reaction solution, and 5 ml to 10 ml of the reaction solution was taken into a centrifuge tube every 15 min. The reaction solution was centrifuged for 5 min at a speed of 4200 r / min using a high-speed desktop centrifuge, and the supernatant was taken. The absorbance was measured at a wavelength of 553 nm using a UV / visible spectrophotometer, and its concentration was calculated based on the Rhodamine B standard working curve, and a graph showing the relationship between the efficiency of photocatalytic degradation of Rhodamine B and time under visible light irradiation was drawn, as shown in FIG. Figure 2 .

[0054] The degradation rate of rhodamine B by the photocatalysts prepared in Comparative Examples 1-2 and Examples 1-4 is the ratio of the concentration of rhodamine B after the photocatalytic reaction to the initial concentration of rhodamine B before illumination. Figure 2 It can be seen that in the process of degradation of rhodamine B by the photocatalysts of comparative examples 1-2 and embodiments 1-4, the concentration of rhodamine B gradually decreases with the increase of degradation time. The degradation efficiency of comparative examples 1 and 2 after 225 min of illumination is 55% and 35% respectively. The degradation efficiency of the photocatalysts prepared according to the steps of the above embodiments 1-4 after 225 min of illumination can reach about 90%, which is significantly improved.

Claims

1. A method for preparing a photocatalyst from coking sulfur paste in coal chemical industry, characterized in that: include: Step 1: Wash the coked sulfur paste produced by the HPF wet oxidation desulfurization process with water, obtain a filtrate and a filter residue after solid-liquid separation, and use the filtrate to prepare the desulfurization liquid; Step 2: The filter residue with sulfur as the main component obtained in step 1 is evaporatively dried and then crushed to a particle size of 5-10 μm, and then fed into a sulfur dissolving reactor with a sodium hydroxide solution having a mass concentration of 10%-20%, and reacted at a temperature of 90°C-95°C to generate sodium polysulfide until the sulfur is completely dissolved, and then filtered to obtain the filter residue and the filtrate containing sodium polysulfide, and the filter residue is fed into a coal pile for coal blending and coking; the chemical reaction formula involved is as follows: ； Step 3, feeding the filtrate containing sodium polysulfide obtained in step 2 into a mixer, and adding a surfactant solution to obtain a uniformly mixed solution; Step 4: add excess acetic acid containing a surfactant to the acidification treatment device, then dropwise add the mixed solution obtained in step 3 to the acidification treatment device, continue the reaction for 1 to 2 hours after the addition is completed, and send the gas at the top of the acidification reactor to the raw gas for purification; the chemical reaction formula involved is as follows: ; Step 5, sending the material obtained after the reaction in step 4 into an aging kettle, separating the filtrate and the precipitate after standing and aging, and sending the filtrate into the regulating tank of the enterprise's biochemical treatment system; Step 6, sending the precipitate obtained in step 5 and industrial ethanol into an elution device at a liquid-to-solid ratio of 5-10 L / kg, performing solid-liquid separation after elution to obtain a filtrate and a filter residue, and recovering ethanol from the filtrate by distillation for recycling; Step seven, drying the filter residue obtained in step six, and the obtained product is α-S with photocatalytic activity.

2. The method according to claim 1, characterized in that: In step 1, the coked sulfur paste produced by the HPF wet oxidation desulfurization method refers to the sulfur paste obtained by filtering or centrifuging sulfur foam, and has a sulfur content of 70% to 80%.

3. The method according to claim 2, characterized in that: In step 1, the coking sulfur paste and water are sent to a water washing device at a liquid-to-solid ratio of 10-20 L / kg for multiple water washings.

4. The method according to claim 1 or 3, characterized in that: In step three, the surfactant refers to a non-ionic polymer that can serve as a template and surface modifier, including at least one of the following surfactants: polyvinyl pyrrolidone PVP-K15, polyvinyl pyrrolidone PVP-K30, octylphenol polyoxyethylene ether OP-10, polyethylene glycol octylphenyl ether TX-100, and polyvinyl alcohol PVA-1788.

5. The method according to claim 4, characterized in that: In step 3, the sodium polysulfide filtrate and the surfactant are mixed in a mixer at a rotation speed of 20 to 50 rmp.

6. The method according to claim 1 or 5, characterized in that: In step three, the amount of surfactant solution added is 5 to 10 times the volume of the filtrate fed into the mixer, and the concentration is 1 g / L to 2 g / L.

7. The method according to claim 6, characterized in that: The surfactant in step 4 is the same as the surfactant in step 3 and has the same effect and concentration.

8. The method according to claim 1 or 7, characterized in that: In step seven, when the filter residue is dried, it is evaporated to dryness at 40-50°C.

9. A photocatalyst, characterized in that: The α-S having photocatalytic activity is obtained by the method according to any one of claims 1 to 8.

10. Use of the photocatalyst according to claim 9 in catalytic degradation of organic pollutants.

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