A method for preparing carbon monoxide oxidation catalyst by using waste vanadium-titanium catalyst and electroplating sludge

Abstract

The application discloses a method for preparing carbon monoxide oxidation catalyst by using waste vanadium-titanium catalyst and electroplating sludge. In the whole preparation process, the metal components in the electroplating sludge and the components in the waste vanadium-titanium catalyst are reacted with each other by the synergistic effect of various physical and chemical treatment methods and additives, so that a complex multi-metal catalyst is formed. The catalyst can be used for photocatalytic oxidation of carbon monoxide, and has remarkable oxidation effect and good application prospect.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of industrial solid waste resource utilization and high value, and particularly relates to a method for preparing carbon monoxide oxidation catalyst by using waste vanadium-titanium catalyst and electroplating sludge. BACKGROUND

[0002] The catalytic oxidation of carbon monoxide (CO) is a common key reaction in environmental catalysis, energy chemical industry and metallurgical tail gas treatment. Traditional CO oxidation catalysts are mostly composed of noble metals (Pt, Pd, Au, etc.) or transition metal oxides (Cu-Mn, Co-Ce, etc.), and their preparation process usually relies on high-purity chemical raw materials, resulting in high cost and unsustainable resources, and the abandoned catalyst itself becomes a new secondary solid waste. Therefore, developing a low-cost, high-activity and long-life CO oxidation catalyst based on industrial solid waste has important scientific and industrial significance for realizing “waste treatment with waste” and carbon emission reduction.

[0003] The waste vanadium-titanium catalyst is mainly derived from tail gas denitrification / sulfur removal devices in the processes of petroleum refining, sulfuric acid industry and coal chemical industry. Taking the sample provided by Hunan Yueyang Changxin New Material Co., Ltd. as an example, the typical chemical composition thereof contains V2O5, TiO2, WO3, SiO2, Al2O3, etc. Vanadium (V) has multiple valence states (V 5+ / V 4+ / V 3+ ) cyclic ability, and is a recognized redox active center; TiO2 (anatase / rutile) is not only an excellent carrier, but also can generate strong mutual interaction (SMSI) through V–O–Ti interface to promote oxygen vacancy generation and migration; WO3 can improve the thermal stability and sulfur poisoning resistance of the catalyst. The solid waste also contains a certain amount of SiO2, Al2O3 and Fe2O3, which can form mullite, ilmenite and other inert skeletons in the subsequent calcination process to inhibit the sintering of the active components. The electroplating sludge is generated in the lime-iron salt co-precipitation treatment process of electroplating wastewater, and is one of the largest heavy metal hazardous wastes at present. Taking the sample provided by Guangdong Shenzhen Greenmax Materials Co., Ltd. as an example, the main components thereof include Fe2O3, Cr2O3, NiO, ZnO, CuO and Al2O3, and the rest are inevitable impurities and loss on ignition. The electroplating sludge is rich in transition metals such as Cr, Ni, Cu and Zn, and the oxides thereof can form spinel, perovskite and other structures under appropriate atmosphere, which have intrinsic redox activity; Fe2O3 can act as an oxygen carrier to participate in CO oxidation through Fe 3+ / Fe 2+ cycle; CaO and SiO2 act as bonding and structural additives to improve the mechanical strength of the catalyst.

[0004] Traditional CO oxidation catalysts usually use high-purity V2O5, TiO2, noble metal salts and other chemical products, which have high cost. The waste vanadium-titanium catalyst and electroplating sludge are mainly stored, co-disposed in cement kiln or recovered by pyrometallurgy, which has low added value and secondary pollution risk. Single solid waste is often difficult to meet the requirements of activity, stability and cost at the same time, and existing researches focus on single solid waste utilization, ignoring the synergistic activation potential between multiple solid wastes. The composition of solid waste fluctuates greatly, and the traditional impregnation-calcination process is difficult to accurately control the active phase structure, resulting in poor performance reproducibility and short service life. SUMMARY

[0005] In view of the above background, the present application proposes a new idea of "co-preparing CO oxidation catalysts from waste vanadium-titanium catalysts and electroplating sludge", which not only solves the problem of high-value utilization of two typical hazardous wastes, but also obtains a high-performance catalyst that can efficiently convert CO at a relatively low temperature (below 150°C), providing a green, low-carbon and economic technical path for industrial tail gas deep purification. Therefore, the purpose of the present application is to provide a method for preparing carbon monoxide oxidation catalysts from waste vanadium-titanium catalysts and electroplating sludge.

[0006] TECHNICAL SOLUTION: In order to solve the above technical problems, the present application provides a method for preparing carbon monoxide oxidation catalysts from waste vanadium-titanium catalysts and electroplating sludge, comprising the following steps:

[0007] (1) Weighing the waste vanadium-titanium catalyst and the electroplating sludge, and placing them in a stirrer to fully mix and evenly mix them to obtain a mixed slurry;

[0008] (2) Mixing the mixed slurry with a sulfuric acid solution, ultrasonicating in an ultrasonic cleaner, then standing and settling, separating the upper clear liquid, and obtaining the acid activated slag as the sediment;

[0009] (3) Mixing the acid activated slag with a sodium hydroxide solution, stirring and reacting to obtain an alkali treated slag;

[0010] (4) Placing the alkali treated slag in a microwave reactor for microwave activation treatment to obtain a microwave activated alkali treated slag;

[0011] (5) Weighing the plant extract and the microwave activated alkali treated slag, stirring them evenly, then transferring the mixture to a hydrothermal reaction kettle for hydrothermal reaction to obtain a hydrothermal activated material;

[0012] (6) Washing the hydrothermal activated material with deionized water until it is neutral, then performing suction filtration separation, then placing the filter cake in a drying box to dry to obtain a dried hydrothermal activated powder, and placing the dried hydrothermal activated powder in a molding equipment to press and form into a catalyst blank with certain shape and strength;

[0013] (7) placing the catalyst blank in a tube furnace, and performing calcination under an air atmosphere to obtain a carbon monoxide oxidation catalyst material.

[0014] The mass ratio of the waste vanadium-titanium catalyst to the electroplating sludge in step (1) is 40-60:100.

[0015] The stirring speed in step (1) is 500-2500 r / min, and the stirring time is 20-60 minutes.

[0016] The concentration of the sulfuric acid solution in step (2) is 2-4 M, and the liquid-solid ratio of the sulfuric acid solution to the mixed slurry is 0.4-0.6:1 (mL / g).

[0017] The ultrasonic frequency in step (2) is 35-45 kHz, the ultrasonic-assisted stirring time is 30-40 minutes, and then the settling time is 1.5-2.5 hours.

[0018] The concentration of the sodium hydroxide solution in step (3) is 4-8 M, the liquid-solid ratio of the sodium hydroxide solution to the acid active slag is 0.4-0.8:1 (mL / g), and the stirring reaction time is 2-4 hours.

[0019] The microwave power in step (4) is 400-600 W, and the microwave time is 5-15 minutes.

[0020] The mass ratio of the plant extract to the microwave-activated alkali residue in step (5) is 0.5-2.5:100, the hydrothermal reaction temperature is 180-220°C, and the hydrothermal reaction time is 8-12 hours.

[0021] The drying temperature in step (6) is 60-120°C, and the drying time is 5-15 hours.

[0022] The calcination temperature in step (7) is 550-750°C, and the calcination time is 4-6 hours.

[0023] Reaction mechanism of the present application: The present application can make the waste vanadium-titanium catalyst and electroplating sludge fully mixed and uniform by high-speed stirring, and the particles collide and disperse with each other. Sulfuric acid as an acid leaching agent reacts with part of metal oxides in the waste vanadium-titanium catalyst and electroplating sludge in an acidic environment, so that it is dissolved into the liquid phase to form the corresponding sulfate. Ultrasonic-assisted stirring helps to destroy the boundary layer on the surface of the particles and accelerate the mass transfer process of the reactants to the surface of the particles. Sodium hydroxide as an alkali leaching agent further reacts with the metal oxides or their sulfates in the acid leaching residue, converting some metal components that are not completely dissolved or in a form that is not easy to utilize during the acid leaching process into soluble salts or forms that are easier to handle. Stirring reaction enables the alkali solution to fully contact with the solid particles, promoting the reaction to proceed and obtaining the alkali treatment residue. The rapid and uniform heating effect of microwave energy intensifies the movement of ions or atoms inside the metal compounds in the alkali treatment residue, destroys the crystal structure or causes phase transition, thereby increasing its activity and reactivity. At the same time, the microwave also initiates some local high-temperature and high-pressure environment, promotes the occurrence of certain chemical reactions, changes the surface properties and microstructure of the residue, forms active sites that are beneficial to subsequent hydrothermal reactions, and obtains microwave-activated alkali residue. The hydrothermal reaction provides a high-temperature and high-pressure closed environment, so that the reaction system can carry out deep chemical reactions under relatively mild conditions. The organic components in the plant extract fully contact and mix with the inorganic components in the microwave-activated alkali residue under hydrothermal conditions, and undergo substance exchange and chemical reaction to form a composite material with specific structure and performance. In this process, the plant extract not only participates in the chemical reaction as a reactant, but also may act as a regulator and stabilizer to control the morphology and size of the product, and finally obtain a hydrothermal-activated material. By fully washing with deionized water, the residual acid, alkali and other soluble impurities in the hydrothermal-activated material are removed to avoid the influence of these impurities on the performance of the subsequent catalyst. Under the high-temperature calcination environment, the organic components in the material are oxidized and decomposed, and part of the metal compounds undergoes oxidation-reduction reaction or crystal type transition, so that the structure of the catalyst is more compact and stable, the dispersion degree of the active components is increased, and the active sites are more fully exposed, and finally a carbon monoxide oxidation catalyst material is obtained.

[0024] Advantages: Compared with the prior art, the present application has the following advantages: The present application realizes the mutual reaction of the metal components in the electroplating sludge and the components in the waste vanadium-titanium catalyst through the synergistic effect of various physical and chemical treatment methods and additives in the whole preparation process, forms a complex multi-metal catalyst, which can be used for photocatalytic oxidation of carbon monoxide, has a significant oxidation effect, and has a good application prospect. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 Flowchart of the treatment method of the present application. DETAILED DESCRIPTION

[0026] The application will be further described below in conjunction with the accompanying drawings and examples.

[0027] Spent vanadium-titanium catalyst: provided by Hunan Yueyang Changxin New Material Co., Ltd., and the main detected components include: 41.26% V2O5, 28.54% TiO2, 11.38% WO3, 7.72% SiO2, 3.65% Al2O3, 2.04% Fe2O3, 1.52% Na2O, 0.71% CaO, 0.53% SO3 and other components (unavoidable impurities and loss on ignition);

[0028] Electroplating sludge: provided by Guangdong Shenzhen Greenmax Technologies Co., Ltd., and the main components include Fe2O3, Cr2O3, NiO, ZnO, CuO, Al2O3 and the rest are unavoidable impurities and loss on ignition.

[0029] Preparation of aloe extract: take the gel scraped from the leaves of three-year-old aloe and immediately mix with color protection liquid containing 0.08% vitamin C at a volume ratio of 1:1; the gel slurry is broken after high-pressure homogenization (pressure 90 MPa), and impurities are removed through a 0.22 μm ceramic microfiltration membrane; the permeate is vacuum concentrated to 1 / 3 of the original volume at 42°C, 4 times the volume of 95% ethanol is added to precipitate polysaccharides, and after 7 hours of standing, centrifugation is performed; the precipitate is redissolved with deionized water, separated through a 50 kDa ultrafiltration membrane, and the high molecular weight polysaccharide solution is collected, freeze-dried (-50°C, vacuum 8 Pa) to obtain aloe polysaccharide, the final product has a polysaccharide content of 45%, an O-acetyl content of 6.2%, and a free anthraquinone content of 0.3 ppm.

[0030] Preparation of malva extract: malva flowers are dried in the shade to a moisture content of 8%, ground through a 30 mesh sieve, and added with deionized water at pH 6.8 at a solid-liquid ratio of 1:18 (g / mL), and extracted at 55°C under ultrasonic power of 250 W for 50 minutes, repeated twice; the extraction liquid is filtered through 200 mesh filter cloth, and concentrated to 1 / 5 of the original volume at 50°C under vacuum, 95% ethanol is slowly added under stirring until the alcohol concentration reaches 72%, and the mixture is placed at 4°C for 18 hours, and the precipitate is freeze-dried after centrifugation; the supernatant is recovered after ethanol removal, and the total flavone fraction is obtained by AB-8 macroporous resin adsorption and elution with 60% ethanol, and the whole process is operated in the dark, and the final product has a total flavone content of 18% and a polysaccharide content of 35%.

[0031] Preparation of rosemary extract: Fresh rosemary leaves were frozen in liquid nitrogen and ground to 0.8 mm in size. The material was added to a buffer solution (pH 4.8) containing 0.8% cellulase and pectinase at a ratio of 1:9. Enzymolysis was performed at 48°C for 100 minutes. Then, 95% ethanol was added to the system to a final concentration of 65%, and the system was heated to 65°C for 1.8 hours of reflux extraction. After the extraction solution was cooled, it was centrifuged at 4500 rpm to obtain the supernatant. The supernatant was concentrated at 45°C under reduced pressure until the alcohol odor disappeared. The water phase was extracted with ethyl acetate three times, and the water phase was purified by a polyamide column. The fraction containing rosemary acid and carnosic acid was collected and spray dried (inlet temperature 170°C, outlet temperature 75°C). The final product had a lipoxygenase inhibition rate of 88% and a total phenol content of 28%.

[0032] Preparation of chamomile flower extract: The flower heads at the initial flowering stage were air-dried at 37°C to a water content of 7%, ground to pass through a 10-mesh sieve, and added to deionized water at a ratio of 1:22. The pH was adjusted to 5.2 with citric acid, and 0.4% β-glucosidase was added. Enzymolysis was performed at 43°C for 75 minutes. Then, the system was heated to 105°C under nitrogen protection for 18 minutes of subcritical water extraction, with the pressure controlled at 0.2 MPa. After the extraction solution was cooled to 20°C, it was centrifuged. The supernatant was adsorbed by a macroporous resin XAD-7HP, and impurities were removed by elution with 25% ethanol. The flavonoid fraction was obtained by elution with 65% ethanol. The eluate was concentrated at 37°C under vacuum and then freeze-dried. The whole process was carried out in the dark under nitrogen protection. The final product had a matricaria chrysoindole content of 0.35% and a total flavonoid content of 20%.

[0033] Preparation of hyacinth extract: The hyacinth bulbs were peeled and dried by heat pump at 45°C. The dried bulbs were ground to 70 mesh and added to 70% ethanol at a ratio of 1:12. Ultrasonic treatment was performed at a power of 300 W and a temperature of 50°C for 40 minutes. Ammonium sulfate was added to the extraction solution to a concentration of 18% (w / v) to form a two-water phase system. The ethanol layer in the upper phase was taken after the system was allowed to stand for 30 minutes. The ethanol layer was concentrated to near dryness at 40°C under reduced pressure. The residue was redissolved in deionized water and purified by a D101 macroporous resin. The eluate was concentrated and then freeze-dried. The final product had a total flavonoid content of 14%, an alkaloid content of 0.08%, and no irritating residue.

[0034] Example 1 Effect of the mass ratio of spent vanadium-titanium-based catalyst to electroplating sludge on the performance of a prepared carbon monoxide oxidation catalyst

[0035] The waste vanadium-titanium catalyst and electroplating sludge were weighed according to the mass ratio of 25:100, 30:100, 35:100, 40:100, 50:100, 60:100, 65:100, 70:100, and 75:100 respectively, and were placed in a stirrer to stir at a speed of 500 r / min for 20 minutes to fully mix and evenly distribute the two. Nine groups of mixed slurry were obtained. The nine groups of mixed slurry were mixed with nine groups of 2M sulfuric acid solution, with a liquid-solid ratio of 0.4:1 (mL / g). Ultrasonic assisted stirring was performed in an ultrasonic cleaner for 30 minutes at an ultrasonic frequency of 35 kHz, followed by standing and settling for 1.5 hours. The upper clear liquid was separated, and nine groups of acid activated slag were obtained. The nine groups of acid activated slag were mixed with nine groups of 4M sodium hydroxide solution, with a liquid-solid ratio of 0.4:1 (mL / g), and stirred for 2 hours to obtain nine groups of alkali treated slag. The nine groups of alkali treated slag were placed in a microwave reactor, and the microwave power was set to 400W and the microwave time was 5 minutes for microwave activation treatment, to obtain nine groups of microwave activated alkali treated slag. According to the mass ratio of 0.5:100, nine groups of plant extracts and nine groups of microwave activated alkali treated slag were weighed and stirred evenly, and then the mixture was transferred to a hydrothermal reactor, with a hydrothermal temperature of 180°C and a hydrothermal time of 8 hours to obtain nine groups of hydrothermal activated materials, wherein the plant extract was aloe extract. The nine groups of hydrothermal activated materials were washed with deionized water until neutral, then subjected to suction filtration separation, and then the filter cake was placed in a drying oven at 60°C for 5 hours to obtain nine groups of dried hydrothermal activated powder. The nine groups of dried hydrothermal activated powder were placed in a molding equipment and pressed into a certain shape and strength under a pressure of 20MPa to obtain nine groups of catalyst blanks. The nine groups of catalyst blanks were placed in a tube furnace and calcined in an air atmosphere, with a calcination temperature of 550°C and a calcination time of 4 hours to obtain nine groups of carbon monoxide oxidation catalyst materials.

[0036] Carbon monoxide oxidation test: at room temperature (25 ± 1°C), nine groups of carbon monoxide oxidation catalyst materials prepared by 185nm vacuum ultraviolet light (VUV) excitation were used to oxidize CO to CO2. The vacuum ultraviolet lamp was a low-pressure mercury lamp (L-type quartz window, 185nm output ≥5mW·cm-2, 254nm cutoff filter optional); the photo-reactor was a cylindrical high-purity quartz tube with an effective optical path L=10.0cm, an inner diameter d=2.0cm, and a volume V=31.4mL; the vacuum system was a turbo molecular pump with a cold trap (limit vacuum <1×10-5Pa); after the reactor was evacuated, a mixed gas (CO:O2:N2=1:1:8 (volume ratio), CO initial concentration C0≈100ppm) was injected at a set total pressure P total =101kPa, the inlet and outlet valves were closed, and the initial concentration C CO,0 was recorded after standing for 5min. -2 -3 total CO,0CO,0 , C CO2,0 , the VUV lamp was turned on and the time was started. The CO and CO2 concentrations were recorded continuously with a sampling frequency of 1 Hz; the reaction time t = 0-30 min (preliminary experiments showed that the reaction tended to equilibrium within 30 min). The lamp power was kept constant, and the incident light intensity I0was measured with an ultraviolet radiation meter (probe 185 nm); the temperature and pressure were recorded every min to ensure that T = 25 ± 1 °C and the P change was <1%. The lamp was turned off, and the gas in the reactor was immediately extracted to determine the final concentration C CO,t , C CO2,t ; possible water was captured with a cold trap, and gas chromatography-thermal conductivity detection (GC-TCD) was used to verify that there were no other carbon-containing products; the experiment was repeated three times, and the average value was taken. The ppm values (C CO,0 and C CO,t ) measured by the online analyzer were converted to molar fractions y (y CO,0 and y CO,t ), and the number of moles of gas in the reactor n = PV / (RT), where T = 298.15 K; the carbon monoxide oxidation efficiency η = (y CO,0 -y CO,t ) / y CO,0 x 100%.

[0037] The test results of this example are shown in Table 1.

[0038] Table 1 Influence of the mass ratio of waste vanadium-titanium catalyst to electroplating sludge on the performance of the prepared carbon monoxide oxidation catalyst

[0039] Spent vanadium-titanium catalyst to electroplating sludge mass ratio Carbon monoxide oxidation efficiency Relative error percentage 25:100 79.52% ±0.2% 30:100 83.49% ±0.1% 35:100 86.37% ±0.1% 40:100 90.75% ±0.1% 50:100 92.16% ±0.1% 60:100 94.01% ±0.1% 65:100 90.28% ±0.1% 70:100 87.84% ±0.2% 75:100 85.93% ±0.1%

[0040] As can be seen from Table 1, when the mass ratio of waste vanadium-titanium catalyst to electroplating sludge is less than 40:100 (for example, the mass ratio of waste vanadium-titanium catalyst to electroplating sludge is 35:100, 30:100, 25:100 in Table 1, and lower ratios not listed in Table 1), the waste vanadium-titanium catalyst is added less, and the reaction between the waste vanadium-titanium catalyst and the electroplating sludge is insufficient, resulting in a significant decrease in the carbon monoxide oxidation efficiency as the mass ratio of waste vanadium-titanium catalyst to electroplating sludge decreases. When the mass ratio of waste vanadium-titanium catalyst to electroplating sludge is equal to 40-60:100 (for example, the mass ratio of waste vanadium-titanium catalyst to electroplating sludge is 40:100, 50:100, 60:100 in Table 1), the waste vanadium-titanium catalyst mainly contains vanadium, titanium and other elements in the form of vanadium oxide and titanium oxide. The electroplating sludge has complex composition and contains various metals and their compounds, such as metal hydroxides or oxides of iron, copper, nickel, and some organic matter and inorganic salts. Through high-speed stirring, the waste vanadium-titanium catalyst and the electroplating sludge can be fully mixed and uniformly dispersed, and the particles can collide and disperse with each other. Sulfuric acid as an acid leaching agent reacts with part of the metal oxides in the waste vanadium-titanium catalyst and the electroplating sludge in an acidic environment, dissolves into the liquid phase, and forms the corresponding sulfate. Ultrasonic-assisted stirring helps to destroy the boundary layer on the surface of the particles and accelerate the mass transfer process of the reactants to the surface of the particles. Finally, the carbon monoxide oxidation efficiency is higher than 90%. When the mass ratio of waste vanadium-titanium catalyst to electroplating sludge is greater than 60:100 (for example, the mass ratio of waste vanadium-titanium catalyst to electroplating sludge is 65:100, 70:100, 75:100 in Table 1, and higher ratios not listed in Table 1), the mass ratio of waste vanadium-titanium catalyst to electroplating sludge is too high, the waste vanadium-titanium catalyst is added in excess, and the reaction between the waste vanadium-titanium catalyst and the electroplating sludge is unbalanced, resulting in a significant decrease in the carbon monoxide oxidation efficiency as the mass ratio of waste vanadium-titanium catalyst to electroplating sludge further increases. Therefore, in general, when the mass ratio of waste vanadium-titanium catalyst to electroplating sludge is equal to 40-60:100, it is most beneficial to improve the oxidation performance of the prepared catalyst for CO in terms of benefits and costs.

[0041] Example 2 Influence of liquid-solid ratio of sulfuric acid solution to mixed slurry on performance of prepared carbon monoxide oxidation catalyst

[0042] Waste vanadium-titanium catalyst and electroplating sludge were weighed at a mass ratio of 60:100 and placed in a mixer. The mixture was stirred at 1500 rpm for 40 minutes to ensure thorough mixing and obtain a slurry. The slurry was then mixed with a 3M sulfuric acid solution, with liquid-to-solid ratios controlled at 0.25:1 (mL / g), 0.3:1 (mL / g), 0.35:1 (mL / g), 0.4:1 (mL / g), 0.5:1 (mL / g), 0.6:1 (mL / g), 0.65:1 (mL / g), 0.7:1 (mL / g), and 0.75 (mL / g). The mixture was then ultrasonically stirred for 35 minutes at a frequency of 40 kHz in an ultrasonic cleaner, followed by settling for 2 hours. The supernatant was separated, and the resulting nine sludge samples were identified as acid-active sludge. Nine groups of acid-activated residues were mixed with a 6M sodium hydroxide solution at a liquid-to-solid ratio of 0.6:1 (mL / g) and stirred for 3 hours to obtain nine groups of alkali-treated residues. These residues were then placed in a microwave reactor, and microwave activation was performed at 500W for 10 minutes to obtain nine groups of microwave-activated alkali-treated residues. Plant extracts and the nine groups of microwave-activated alkali-treated residues were weighed at a mass ratio of 1.5:100, stirred thoroughly, and then transferred to a hydrothermal reactor. The hydrothermal temperature was set at 200℃ for 10 hours to obtain nine groups of hydrothermally activated materials, wherein the plant extract was mallow extract. The hydrothermally activated materials were thoroughly washed with deionized water until neutral, then filtered. The filter cake was then placed in a drying oven and dried at 90℃ for 10 hours to obtain nine groups of dried hydrothermally activated powders. Nine groups of dried hydrothermally activated powders were placed in a molding device and pressed into catalyst blanks with a certain shape and strength under a pressure of 25 MPa. The catalyst blanks were then placed in a tube furnace and calcined in an air atmosphere at a temperature of 650℃ for 5 hours to obtain nine groups of carbon monoxide oxidation catalyst materials.

[0043] The carbon monoxide oxidation test and carbon monoxide oxidation efficiency calculation were the same as in Example 1. The test results of this example are shown in Table 2.

[0044] Table 2 Effect of the liquid-solid ratio of sulfuric acid solution and mixed slurry on the performance of the prepared carbon monoxide oxidation catalyst

[0045] Sulfuric acid solution to mixed slurry liquid to solid ratio Carbon monoxide oxidation efficiency Relative error percentage 0.25:1 (mL / g) 86.71% ±0.1% 0.3:1 (mL / g) 88.32% ±0.1% 0.35:1 (mL / g) 90.85% ±0.1% 0.4:1 (mL / g) 94.29% ±0.1% 0.5:1 (mL / g) 95.38% ±0.1% 0.6:1 (mL / g) 96.91% ±0.1% 0.65:1 (mL / g) 93.43% ±0.2% 0.7:1 (mL / g) 91.58% ±0.1% 0.75 (mL / g) 89.74% ±0.1%

[0046] As can be seen from Table 2, when the liquid-solid ratio of sulfuric acid solution to mixed slurry is less than 0.4:1 (mL / g) (for example, the liquid-solid ratio of sulfuric acid solution to mixed slurry = 0.35:1 (mL / g), 0.3:1 (mL / g), 0.25:1 (mL / g) in Table 2, and lower ratios not listed in Table 2), less sulfuric acid solution is added, and the reaction between the sulfuric acid solution and the mixed slurry is insufficient, resulting in a significant decrease in the carbon monoxide oxidation efficiency as the liquid-solid ratio of sulfuric acid solution to mixed slurry decreases. When the liquid-solid ratio of sulfuric acid solution to mixed slurry is equal to 0.4-0.6:1 (mL / g) (for example, the liquid-solid ratio of sulfuric acid solution to mixed slurry = 0.4:1 (mL / g), 0.5:1 (mL / g), 0.6:1 (mL / g) in Table 2), sulfuric acid as an acid leaching agent reacts with part of the metal oxides in the waste vanadium-titanium catalyst and electroplating sludge in an acidic environment, causing them to dissolve into the liquid phase to form corresponding sulfates. Ultrasonic-assisted stirring helps to break the boundary layer on the surface of the particles and accelerate the mass transfer process of the reactants to the surface of the particles. Ultimately, the carbon monoxide oxidation efficiency is higher than 90%. When the liquid-solid ratio of sulfuric acid solution to mixed slurry is greater than 0.6:1 (mL / g) (for example, the liquid-solid ratio of sulfuric acid solution to mixed slurry = 0.65:1 (mL / g), 0.7:1 (mL / g), 0.75 (mL / g) in Table 2, and higher ratios not listed in Table 2), the liquid-solid ratio of sulfuric acid solution to mixed slurry is too high, and the sulfuric acid solution is added in excess, resulting in an imbalance in the reaction between the sulfuric acid solution and the mixed slurry, which leads to a significant decrease in the carbon monoxide oxidation efficiency as the liquid-solid ratio of sulfuric acid solution to mixed slurry further increases. Therefore, in general, when the liquid-solid ratio of sulfuric acid solution to mixed slurry is equal to 0.4-0.6:1 (mL / g), it is most beneficial to improve the carbon monoxide oxidation performance of the prepared catalyst in terms of benefits and costs.

[0047] Example 3 Effect of plant extract and microwave-activated alkali residue mass ratio on the performance of the prepared carbon monoxide oxidation catalyst

[0048] The waste vanadium-titanium catalyst and electroplating sludge were weighed according to a mass ratio of 60:100, put into a stirrer, and stirred at a speed of 2500 r / min for 60 min to make them fully mixed and uniform, to obtain a mixed slurry. The mixed slurry was mixed with a sulfuric acid solution with a concentration of 4 M, and the liquid-solid ratio was controlled at 0.6:1 (mL / g). Ultrasonic-assisted stirring was performed in an ultrasonic cleaner for 40 min, and the ultrasonic frequency was 45 kHz, followed by standing and settling for 2.5 h. The supernatant was separated, and the obtained sediment was an acid active residue. The acid active residue was mixed with a sodium hydroxide solution with a concentration of 8 M, and the liquid-solid ratio was 0.8:1 (mL / g). The mixture was stirred for 4 h to obtain an alkali-treated residue. The alkali-treated residue was placed in a microwave reactor, and the microwave power was set at 600 W. The microwave time was 15 min, and microwave activation treatment was performed to obtain a microwave-activated alkali-treated residue. Plant extracts and the microwave-activated alkali-treated residue were weighed according to mass ratios of 0.25:100, 0.3:100, 0.4:100, 0.5:100, 1.5:100, 2.5:100, 2.75:100, 3:100, and 3.25:100, respectively, and were uniformly stirred. Then, the mixture was transferred to a hydrothermal reactor, and the hydrothermal temperature was set at 220 ℃. The hydrothermal time was 12 h to obtain nine groups of hydrothermal activated materials, wherein the plant extracts were rosemary extracts. The nine groups of hydrothermal activated materials were washed with deionized water until neutral, and then were separated by suction filtration. Subsequently, the filter cake was placed in a drying oven and dried at 120 ℃ for 15 h to obtain nine groups of dried hydrothermal activated powders. The nine groups of dried hydrothermal activated powders were placed in a molding device and were pressed into catalyst blanks under a pressure of 30 MPa. The nine groups of catalyst blanks were placed in a tube furnace and were calcined in an air atmosphere. The calcination temperature was set at 750 ℃, and the calcination time was 6 h to obtain nine groups of carbon monoxide oxidation catalyst materials.

[0049] The carbon monoxide oxidation test and the calculation of the carbon monoxide oxidation efficiency were the same as in Example 1. The test results of this example are shown in Table 3.

[0050] Table 3 Influence of the mass ratio of plant extracts and microwave-activated alkali-treated residue on the performance of the prepared carbon monoxide oxidation catalyst

[0051] Plant extract and microwave-activated base residue mass ratio Carbon monoxide oxidation efficiency Relative error percentage 0.25:100 89.92% ±0.1% 0.3:100 90.56% ±0.1% 0.4:100 92.15% ±0.2% 0.5:100 96.97% ±0.1% 1.5:100 97.36% ±0.1% 2.5:100 98.02% ±0.1% 2.75:100 96.41% ±0.1% 3:100 93.95% ±0.1% 3.25:100 92.79% ±0.2%

[0052] As can be seen from Table 3, when the mass ratio of plant extract and microwave-activated alkaline residue is less than 0.5:100 (for example, the mass ratio of plant extract and microwave-activated alkaline residue is 0.4:100, 0.3:100, 0.25:100 in Table 3, and lower ratios not listed in Table 3), the plant extract is added in small amounts, and the reaction between the plant extract and the microwave-activated alkaline residue is insufficient, resulting in a significant decrease in the carbon monoxide oxidation efficiency as the mass ratio of plant extract and microwave-activated alkaline residue decreases. When the mass ratio of plant extract and microwave-activated alkaline residue is equal to 0.5-2.5:100 (for example, the mass ratio of plant extract and microwave-activated alkaline residue is 0.5:100, 1.5:100, 2.5:100 in Table 3), the organic components in the plant extract and the inorganic components in the microwave-activated alkaline residue are fully contacted and mixed under hydrothermal conditions, and substance exchange and chemical reactions occur, forming a composite material with specific structure and performance. In this process, the plant extract not only participates in the chemical reaction as a reactant, but also may act as a regulator and stabilizer to control the morphology and size of the product, and ultimately obtain a hydrothermal activated material. By thoroughly washing with deionized water, the residual acid, base and other soluble impurities in the hydrothermal activated material are removed, avoiding the influence of these impurities on the performance of the subsequent catalyst. Under high-temperature calcination environment, the organic components in the material are oxidized and decomposed, and part of the metal compounds undergo oxidation-reduction reaction or crystal transformation, so that the structure of the catalyst is more compact and stable, the dispersion degree of the active component is increased, and the active sites are more fully exposed, and ultimately a carbon monoxide oxidation catalyst material is obtained. Finally, the carbon monoxide oxidation efficiency is higher than 96%. When the mass ratio of plant extract and microwave-activated alkaline residue is greater than 2.5:100 (for example, the mass ratio of plant extract and microwave-activated alkaline residue is 2.75:100, 3:100, 3.25:100 in Table 3, and higher ratios not listed in Table 3), the mass ratio of plant extract and microwave-activated alkaline residue is too high, the plant extract is added in excess, and the reaction between the plant extract and the microwave-activated alkaline residue is unbalanced, resulting in a significant decrease in the carbon monoxide oxidation efficiency as the mass ratio of plant extract and microwave-activated alkaline residue further increases. Therefore, in general, when the mass ratio of plant extract and microwave-activated alkaline residue is equal to 0.5-2.5:100, it is most beneficial to improve the oxidation performance of the prepared catalyst for CO in terms of benefits and costs.

[0053] Example 4 Effect of plant extract on the performance of the prepared carbon monoxide oxidation catalyst

[0054] The waste vanadium-titanium catalyst and the electroplating sludge were weighed according to a mass ratio of 40:100, placed in a stirrer, and stirred at a speed of 2500 r / min for 40 min to make them fully mixed and uniform, thereby obtaining a mixed slurry. The mixed slurry was mixed with a sulfuric acid solution with a concentration of 4 M, and the liquid-solid ratio was controlled at 0.6:1 (mL / g). The mixture was subjected to ultrasonic-assisted stirring in an ultrasonic cleaner for 40 min at an ultrasonic frequency of 45 kHz, and then was left to stand for 2.5 h for sedimentation. The supernatant was separated, and the obtained sediment was an acid active residue. The acid active residue was mixed with a sodium hydroxide solution with a concentration of 8 M, and the liquid-solid ratio was 0.6:1 (mL / g). The mixture was stirred for 3 h for reaction, thereby obtaining an alkali-treated residue. The alkali-treated residue was placed in a microwave reactor, and the microwave power was set at 600 W. The microwave time was 15 min, and the microwave-activated alkali-treated residue was obtained. The plant extract and the microwave-activated alkali-treated residue were weighed according to a mass ratio of 2.5:100, and were uniformly stirred. Then, the mixture was transferred to a hydrothermal reactor, and the hydrothermal temperature was set at 220℃. The hydrothermal time was 12 h, and five groups of hydrothermal-activated materials were obtained. The plant extract in each group was one of aloe extract, mallow extract, rosemary extract, chamomile extract, and hyacinth extract. The five groups of hydrothermal-activated materials were washed with deionized water until neutral, and then were subjected to suction filtration separation. Subsequently, the filter cake was placed in a drying oven, and was dried at 120℃ for 15 h, thereby obtaining five groups of dried hydrothermal-activated powders. The five groups of dried hydrothermal-activated powders were placed in a molding device, and were pressed into a certain shape and strength under a pressure of 30 MPa, thereby obtaining five groups of catalyst blanks. The catalyst blanks were placed in a tube furnace, and were calcined in an air atmosphere. The calcination temperature was set at 750℃, and the calcination time was 6 h, thereby obtaining five groups of carbon monoxide oxidation catalyst materials.

[0055] The carbon monoxide oxidation test and the calculation of the carbon monoxide oxidation efficiency were the same as in Example 1. The test results of this example are shown in Table 4.

[0056] Table 4 Influence of plant extract on the performance of the prepared carbon monoxide oxidation catalyst

[0057] Plant extract Carbon monoxide oxidation efficiency Relative error percentage Aloe extract 97.02% ±0.1% Malva extract 97.31% ±0.1% Rosemary extract 97.29% ±0.1% Chamomile extract 96.98% ±0.1% Hyacinth extract 97.15% ±0.1%

[0058] As shown in Table 4, when the plant extract is any one of aloe extract, mallow extract, rosemary extract, chamomile extract, and hyacinth extract, the oxidation performance of the prepared catalyst for CO has no significant difference.

[0059] Comparative Example Influence of different processes on the performance of the prepared carbon monoxide oxidation catalyst

[0060] The process of the present application: according to the mass ratio 60:100, the waste vanadium-titanium catalyst and electroplating sludge are weighed and placed in a stirrer, stirred at a speed of 2500 r / min for 40 minutes, so that the two are fully mixed and uniform, to obtain a mixed slurry. The mixed slurry is mixed with a sulfuric acid solution with a concentration of 3M, and the liquid-solid ratio is controlled at 0.6:1 (mL / g). Ultrasonic assisted stirring is carried out in an ultrasonic cleaner for 40 minutes, and the ultrasonic frequency is 45 kHz, then it is left to settle for 2 hours, the supernatant is separated, and the obtained sediment is acid active slag. The acid active slag is mixed with a sodium hydroxide solution with a concentration of 8M, the liquid-solid ratio is 0.6:1 (mL / g), and the stirring reaction is carried out for 3 hours to obtain alkali treated slag. The alkali treated slag is placed in a microwave reactor, the microwave power is set to 600W, the microwave time is 15 minutes, and microwave activation treatment is carried out to obtain microwave activated alkali treated slag. According to the mass ratio 2.5:100, the plant extract and the microwave activated alkali treated slag are weighed and stirred uniformly, then the mixture is transferred to a hydrothermal reaction kettle, the hydrothermal temperature is set to 220℃, and the hydrothermal time is 12 hours to obtain hydrothermal activated material, wherein the plant extract is a hyacinth extract. The hydrothermal activated material is washed with deionized water until neutral, then it is separated by suction filtration, then the filter cake is placed in a drying oven and dried at 60℃ for 5 hours to obtain dried hydrothermal activated powder. The dried powder is placed in a molding equipment and pressed into a catalyst blank with a certain shape and strength under a pressure of 30MPa. The catalyst blank is placed in a tube furnace and calcined in an air atmosphere, the calcination temperature is set to 750℃, and the calcination time is 6 hours to obtain a carbon monoxide oxidation catalyst material.

[0061] Comparative Process 1: The electroplating sludge was mixed with a sulfuric acid solution with a concentration of 3 M, and the liquid-solid ratio was controlled at 0.6:1 (mL / g). Ultrasonic-assisted stirring was performed in an ultrasonic cleaner for 40 minutes at an ultrasonic frequency of 45 kHz, followed by standing and settling for 2 hours. The supernatant was separated, and the obtained sediment was acid-activated residue. The acid-activated residue was mixed with a sodium hydroxide solution with a concentration of 8 M, and the liquid-solid ratio was 0.6:1 (mL / g). Stirring was performed for 3 hours to obtain alkali-treated residue. The alkali-treated residue was placed in a microwave reactor, and the microwave power was set to 600 W. Microwave activation treatment was performed for 15 minutes to obtain microwave-activated alkali-treated residue. The plant extract and the microwave-activated alkali-treated residue were weighed according to a mass ratio of 2.5:100, and stirring was performed. Then, the mixture was transferred to a hydrothermal reaction kettle, and the hydrothermal temperature was set to 220°C. Hydrothermal treatment was performed for 12 hours to obtain hydrothermal-activated material, wherein the plant extract was a hyacinth extract. The hydrothermal-activated material was washed with deionized water until neutral, and then suction filtration was performed. The filter cake was placed in a drying box and dried at 60°C for 5 hours to obtain dried hydrothermal-activated powder. The dried powder was placed in a molding device, and molding was performed under a pressure of 30 MPa to obtain a catalyst blank with a certain shape and strength. The catalyst blank was placed in a tube furnace, and calcination was performed in an air atmosphere. The calcination temperature was set to 750°C, and the calcination time was 6 hours to obtain a carbon monoxide oxidation catalyst material.

[0062] Comparative Process 2: The waste vanadium-titanium catalyst was mixed with a sulfuric acid solution with a concentration of 3 M, and the liquid-solid ratio was controlled at 0.6:1 (mL / g). Ultrasonic-assisted stirring was performed in an ultrasonic cleaner for 40 minutes at an ultrasonic frequency of 45 kHz, followed by standing and settling for 1.5-2.5 hours. The supernatant was separated, and the obtained sediment was acid-activated residue. The acid-activated residue was mixed with a sodium hydroxide solution with a concentration of 8 M, and the liquid-solid ratio was 0.6:1 (mL / g). Stirring was performed for 3 hours to obtain alkali-treated residue. The alkali-treated residue was placed in a microwave reactor, and the microwave power was set to 600 W. Microwave activation treatment was performed for 15 minutes to obtain microwave-activated alkali-treated residue. The plant extract and the microwave-activated alkali-treated residue were weighed according to a mass ratio of 2.5:100, and stirring was performed. Then, the mixture was transferred to a hydrothermal reaction kettle, and the hydrothermal temperature was set to 220°C. Hydrothermal treatment was performed for 12 hours to obtain hydrothermal-activated material, wherein the plant extract was a hyacinth extract. The hydrothermal-activated material was washed with deionized water until neutral, and then suction filtration was performed. The filter cake was placed in a drying box and dried at 60°C for 5 hours to obtain dried hydrothermal-activated powder. The dried powder was placed in a molding device, and molding was performed under a pressure of 30 MPa to obtain a catalyst blank with a certain shape and strength. The catalyst blank was placed in a tube furnace, and calcination was performed in an air atmosphere. The calcination temperature was set to 750°C, and the calcination time was 6 hours to obtain a carbon monoxide oxidation catalyst material.

[0063] The carbon monoxide oxidation test and the carbon monoxide oxidation efficiency calculation are the same as those in Example 1. The test results of the present comparative example are shown in Table 5.

[0064] Table 5 Influence of different comparative processes on the performance of the prepared carbon monoxide oxidation catalyst

[0065] Process type Carbon monoxide oxidation efficiency Relative error percentage Inventive process 97.25% ±0.1% Comparative process 1 45.17% ±0.1% Comparative process 2 42.84% ±0.1%

[0066] As shown in Table 5, the carbon monoxide oxidation efficiency of the carbon monoxide oxidation catalyst prepared by the process of the present application is significantly higher than that of comparative process 1 and comparative process 2, and is higher than the sum of the two.

Claims

1. A method for preparing a carbon monoxide oxidation catalyst using waste vanadium-titanium catalyst and electroplating sludge, characterized in that, Includes the following steps: (1) Weigh the waste vanadium-titanium catalyst and electroplating sludge, put them in a mixer and stir to mix them thoroughly and evenly to obtain a mixed slurry; (2) Mix the mixed slurry with sulfuric acid solution, sonicate in an ultrasonic cleaner, then let it stand to settle, separate the supernatant, and the resulting sludge is acid-active sludge; (3) Mix the acid-active slag with sodium hydroxide solution and stir to react to obtain alkali-treated slag; (4) The alkali-treated residue is placed in a microwave reactor for microwave activation treatment to obtain microwave-activated alkali-treated residue; (5) Weigh the plant extract and microwave-activated alkali treatment residue, stir evenly, and then transfer the mixture to a hydrothermal reactor for hydrothermal reaction to obtain hydrothermal activated material; (6) The hydrothermal activated material is thoroughly washed with deionized water until neutral, then filtered and separated. The filter cake is then placed in a drying oven to dry and obtain dry hydrothermal activated powder. The dried hydrothermal activated powder is placed in a molding equipment and pressed to obtain catalyst blank. (7) The catalyst blank is placed in a tube furnace and calcined in an air atmosphere to obtain carbon monoxide oxidation catalyst material; The main components of the electroplating sludge are Fe2O3, Cr2O3, NiO, ZnO, CuO, and Al2O3, with the remainder being unavoidable impurities and loss on ignition. The plant extracts include one of the following: aloe vera extract, mallow extract, rosemary extract, chamomile extract, and hyacinth extract.

2. The method for preparing a carbon monoxide oxidation catalyst using waste vanadium-titanium catalyst and electroplating sludge according to claim 1, characterized in that, The mass ratio of the waste vanadium-titanium catalyst to the electroplating sludge in step (1) is 40~60:

100.

3. The method for preparing a carbon monoxide oxidation catalyst using waste vanadium-titanium catalyst and electroplating sludge according to claim 1, characterized in that, In step (1), the stirring speed is 500~2500 r / min and the stirring time is 20~60 minutes.

4. The method for preparing a carbon monoxide oxidation catalyst using waste vanadium-titanium catalyst and electroplating sludge according to claim 1, characterized in that, The concentration of the sulfuric acid solution in step (2) is 2~4M, and the liquid-solid ratio of the sulfuric acid solution to the mixed slurry is 0.4~0.6:1mL / g.

5. The method for preparing a carbon monoxide oxidation catalyst using waste vanadium-titanium catalyst and electroplating sludge according to claim 1, characterized in that, In step (2), the ultrasonic frequency is 35~45kHz, and ultrasonic-assisted stirring is performed for 30~40 minutes, followed by standing and settling for 1.5~2.5 hours.

6. The method for preparing a carbon monoxide oxidation catalyst using waste vanadium-titanium catalyst and electroplating sludge according to claim 1, characterized in that, The concentration of the sodium hydroxide solution in step (3) is 4~8M, the liquid-solid ratio of sodium hydroxide solution to acid-active slag is 0.4~0.8:1mL / g, and the reaction is stirred for 2~4 hours.

7. The method for preparing a carbon monoxide oxidation catalyst using waste vanadium-titanium catalyst and electroplating sludge according to claim 1, characterized in that, In step (4), the microwave power is 400~600W and the microwave time is 5~15 minutes.

8. The method for preparing a carbon monoxide oxidation catalyst using waste vanadium-titanium catalyst and electroplating sludge according to claim 1, characterized in that, In step (5), the mass ratio of plant extract to microwave-activated alkaline residue is 0.5~2.5:100, the hydrothermal reaction temperature is 180~220℃, and the hydrothermal reaction time is 8~12 hours.

9. The method for preparing a carbon monoxide oxidation catalyst using waste vanadium-titanium catalyst and electroplating sludge according to claim 1, characterized in that, In step (6), the drying temperature is 60~120℃ and the drying time is 5~15 hours.

10. The method for preparing a carbon monoxide oxidation catalyst using waste vanadium-titanium catalyst and electroplating sludge according to claim 1, characterized in that, In step (7), the roasting temperature is 550~750℃ and the roasting time is 4~6 hours.

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