Composite catalyst based on nickel / copper-hexamercaptobenzene nanoparticle loaded iron, nickel and palladium as well as preparation method and application of composite catalyst

Abstract

The invention discloses a nickel / copper-hexamercaptobenzene composite catalyst loaded with iron, nickel and palladium as well as a preparation method and application of the nickel / copper-hexamercaptobenzene composite catalyst. The catalyst takes nickel / copper-hexamercaptobenzene nanoparticles as a carrier and is loaded with active components of iron, nickel and palladium, and the preparation method comprises the following steps: synthesizing the carrier under an anaerobic condition, performing ultrasonic stripping, and loading Fe, Ni and Pd through chemical deposition in sequence under the protection of inert gas. Pd in the obtained catalyst is highly dispersed, Fe and Ni exist in a crystalline phase form, and the carrier is fully stripped and is rich in defects. The catalyst is used for degrading tetrabromobisphenol A in water, under the conditions that the pH is 3-5, the adding amount of the catalyst is 0.125 g / L and room-temperature ultrasonic assistance is carried out, the degradation rate of 98% or above can be achieved for a TBBPA solution with the initial concentration smaller than or equal to 10 mg / L within 20 min, and the catalyst has the advantages of being efficient and rapid.

Description

TECHNICAL FIELD

[0001] The present application relates to a composite catalyst, in particular to a composite catalyst based on nickel / copper-hexathiol benzene nanoparticle loaded with iron, nickel and palladium and a preparation method and application thereof. BACKGROUND

[0002] Brominated diphenyl ethers are a kind of flame retardants commonly used in plastics and electronic products. With the increase of industrial production and consumption, the environmental pollution problem of tetrabromobisphenol A (TBBPA) is becoming increasingly serious. TBBPA has strong bioaccumulation and persistence, causing significant impact on water and soil ecosystems. Existing studies have shown that the toxicity of TBBPA not only threatens aquatic organisms, but also may potentially harm human health, so it is urgent to develop efficient removal and degradation technologies to reduce its environmental risk.

[0003] Currently, the removal methods of TBBPA mainly include physical adsorption, chemical oxidation, microbial degradation, etc. However, these methods generally have the disadvantages of low efficiency, high cost or complex processing flow, etc. For example, physical adsorption is simple, but it is difficult to improve the removal efficiency; chemical oxidation method needs to use strong oxidizing agents, which may cause secondary pollution; and microbial degradation is limited by environmental conditions and microbial population. Elemental zero-valent iron has good reducing ability and is low in price, but the surface area of elemental zero-valent iron is small, the reaction speed is slow, and the degradation rate of TBBPA is not high. Therefore, how to construct an iron-based nanocomposite material with high dispersion, high activity and good stability to achieve efficient and rapid degradation of TBBPA is still a technical problem to be solved at present. SUMMARY

[0004] The purpose of the present application is to provide a composite catalyst based on nickel / copper-hexathiol benzene nanoparticle loaded with iron, nickel and palladium and a preparation method and application thereof.

[0005] The composite catalyst based on nickel / copper-hexathiol benzene nanoparticle loaded with iron, nickel and palladium according to the present application takes nickel / copper-hexathiol benzene nanoparticle as the carrier and takes iron, nickel and palladium as the active components; the molar ratio of nickel / copper-hexathiol benzene nanoparticle, Fe, Ni and Pd is 10: (9-13): (0.3-1): (0.03-0.08).

[0006] Preferably, the composite catalyst has the following X-ray diffraction characteristic peaks: characteristic diffraction peaks corresponding to the 110, 200 and 211 crystal planes of Fe appear at 2θ=44.7°, 65.1° and 82.4°, characteristic diffraction peaks corresponding to the 111, 200 and 220 crystal planes of Ni appear at 2θ=44.508°, 51.847° and 76.372°; the mass fraction of Pd is 0.26wt% and is uniformly dispersed, and there is no characteristic diffraction peak of Pd. The nickel / copper-hexathiol benzene nanoparticles are in exfoliated state, with a size of 40-50 nm and defect structure, detected by a scanning electron microscope; and Fe, Ni and Pd are loaded on the surface of the nickel / copper-hexathiol benzene nanoparticles, detected by X-ray photoelectron spectroscopy.

[0007] The preparation method of the composite catalyst comprises the following steps: Step one: preparing nickel / copper-hexathiol benzene nanoparticles; Step two: exfoliating the nickel / copper-hexathiol benzene nanoparticles; Step three: loading Fe, Ni and Pd active components.

[0008] Preferably, the nickel / copper-hexathiol benzene nanoparticles in step one are prepared by reacting hexathiol benzene, CH3ONa, copper nitrate and nickel nitrate at a molar ratio of 0.5:3:1.5:1.5, and the specific steps comprise: Step S11: dissolving hexathiol benzene and sodium methoxide in deaerated ethanol under a nitrogen atmosphere without oxygen throughout to obtain a deprotonated hexathiol benzene solution; Step S12: injecting a copper nitrate-nickel nitrate ethanol solution into the stirred deprotonated hexathiol benzene solution by using a syringe pump to generate black precipitates; Step S13: filtering the black precipitates, washing them with water, ethanol and acetone in sequence, and then vacuum drying to obtain nickel / copper-hexathiol benzene nanoparticles.

[0009] Preferably, the nickel / copper-hexathiol benzene nanoparticles in step one are prepared by reacting hexathiol benzene, CH3ONa, copper nitrate and nickel nitrate at a molar ratio of 0.5:3:1.5:1.5, Further preferably, step one specifically comprises: Step S11: dissolving 0.5 mmol of hexathiol benzene and 3 mmol of sodium methoxide in 30 mL of deaerated ethanol under a nitrogen atmosphere without oxygen throughout to obtain a deprotonated hexathiol benzene solution; Step S12: slowly injecting 10 mL of a copper nitrate-nickel nitrate ethanol solution into the vigorously stirred deprotonated hexathiol benzene solution by using a syringe pump to generate black precipitates; Step S13: filtering the black precipitates, washing them with water, ethanol and acetone in sequence, and then vacuum drying in a vacuum drying box for 24 hours to obtain nickel / copper-hexathiol benzene nanoparticles.

[0010] Preferably, step two specifically comprises: Step S21: grinding the nickel / copper-hexathiol benzene nanoparticles prepared in step one into powder, and dispersing them in anhydrous ethanol at a concentration of 1-6 mg / mL; Step S22: ultrasonic treating the dispersion. Step S23: After the ultrasonic treatment, the filtrate is separated by suction filtration, the residue is washed with deionized water and dried to obtain the stripped nickel / copper-hexamercaptobenzene nanoparticle powder.

[0011] Preferably, step three specifically comprises: Step S31: Dissolve the nickel / copper-hexamercaptobenzene nanoparticle powder obtained in step two in deionized water and place it in an oxygen-free environment; Step S32: First, add the ferric chloride solution, and then ultrasonic stirring and standing adsorption; then add excess sodium borohydride solution and stand; Step S33: Add nickel chloride solution and ultrasonic, then add palladium chloride solution and ultrasonic, so that Fe, Ni and Pd adhere to the surface of the nickel / copper-hexamercaptobenzene nanoparticles; Step S34: Finally, filter, wash and dry to obtain the composite catalyst.

[0012] Preferably, the temperature control accuracy of the vacuum drying in step one is 60±1℃, and the vacuum degree is ≤10Pa; the flow accuracy of the syringe pump is 1ml / min±0.01ml / min. The concentration of the copper nitrate-nickel nitrate ethanol solution is 0.3mol / L.

[0013] Preferably, the dispersion liquid is treated by the ultrasonic cell disrupter for 14-18 hours in step two, the frequency of the ultrasonic cell disrupter is 15-30kHz, the running mode is running for 7-9 seconds and pausing for 1.5-2.5 seconds, and the maximum power of the ultrasonic cell disrupter is 600W. Further preferably, the dispersion liquid is treated by the ultrasonic cell disrupter for 16 hours, the frequency of the ultrasonic cell disrupter is 20kHz, and the running mode is running for 8 seconds and pausing for 2 seconds. Preferably, the inert gas used in the oxygen-free environment in step S31 is nitrogen or helium, and the purity of the inert gas is >99%; in step S32, the ferric chloride solution is first added, ultrasonic stirring is performed for 15-25 minutes, and then standing adsorption is performed for 25-35 minutes; then, the excess sodium borohydride solution is added and stood for 25-35 minutes; in step S33, the nickel chloride solution is added and ultrasonic is performed for 25-35 minutes, the palladium chloride solution is added and ultrasonic is performed for 25-35 minutes, so that Fe, Ni and Pd adhere to the surface of the nickel / copper-hexamercaptobenzene nanoparticles.

[0014] Further preferably, step three specifically comprises: Step S31: Dissolve the nickel / copper-hexamercaptobenzene nanoparticle powder obtained in step two in deionized water and place it in an oxygen-free environment with an inert gas purity of >99%; Step S32: First, add the ferric chloride solution, and then ultrasonic stirring and standing adsorption; then add excess sodium borohydride solution and stand; Step S33: Then, a nickel chloride solution is added sequentially for 30 minutes under ultrasonic, and a palladium chloride solution is added sequentially for 30 minutes under ultrasonic, so that Fe, Ni and Pd are attached to the surface of the nickel / copper-hexathiol benzene nanoparticles; Step S34: Finally, filtration, washing and drying are performed to obtain the composite catalyst.

[0015] Preferably, the resistivity of the deionized water in step three is greater than or equal to 18.2 MΩ·cm; and the filtration operations in steps one and three are both performed using a 0.22 μm water filter membrane.

[0016] The application of the composite catalyst in degrading tetrabromobisphenol A includes: adding the composite catalyst to a TBBPA aqueous solution with a pH of 3-5, and performing a catalytic degradation reaction under ultrasonic assistance and at room temperature. When degrading TBBPA, the addition amount of the composite catalyst is 0.125 g / L, the initial pH of the TBBPA solution is 3-5, and when the initial concentration of TBBPA is less than or equal to 10 mg / L, the degradation rate of TBBPA within 20 minutes is greater than or equal to 98%.

[0017] Advantages: Compared with the prior art, the nickel / copper-hexathiol benzene nanoparticle loaded iron / nickel / palladium composite material has the following significant advantages: in addition to the advantages of high specific surface area, fast reaction and prevention of the aggregation of nano-iron, the material also forms a galvanic cell structure through the interaction between iron, nickel and palladium, further promoting the corrosion reaction of iron, thereby significantly improving the reaction speed. Specifically, copper and palladium, as conductive materials, form a potential difference with the surface of iron, promoting the transfer of electrons and the oxidation corrosion of iron. This galvanic cell effect not only enhances the catalytic activity of iron, but also promotes the supply of electrons during the reaction process, reduces the passivation phenomenon of iron, and further improves the reaction efficiency. In this way, the composite material can quickly start and maintain a high reaction speed when degrading target substances, solving the problem of slow reaction of traditional 0-valence iron materials, and avoiding the aggregation of nano-iron. In general, the nickel / copper-hexathiol benzene nanoparticle loaded iron / nickel / palladium composite material greatly improves its application potential in the fields of environmental governance and wastewater treatment through the galvanic cell effect, excellent dispersibility and stability. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 X-ray diffraction pattern of Cu-BHT@Fe / Ni / Pd catalyst.

[0019] Figure 2 Scanning electron microscope picture of Cu-BHT@Fe / Ni / Pd catalyst.

[0020] Figure 3 XPS full spectrum of Cu-BHT@Fe / Ni / Pd catalyst, element characteristic peaks are marked.

[0021] Figure 4 Figure for catalytic degradation performance of Fe / Ni / Pd catalysts supported on different substrates.

[0022] Figure 5 Figure for catalytic degradation performance of Cu-BHT supported different metal catalysts.

[0023] Figure 6 Figure for catalytic degradation performance of Cu-BHT@Fe / Ni / Pd catalysts supported with different iron ratios.

[0024] Figure 7 Figure for catalytic degradation performance of Cu-BHT@Fe / Ni / Pd catalysts supported with different nickel ratios.

[0025] Figure 8 Figure for catalytic degradation performance of Cu-BHT@Fe / Ni / Pd catalysts supported with different palladium ratios.

[0026] Figure 9 Figure for catalytic degradation performance of Cu-BHT@Fe / Ni / Pd catalysts with different PH values.

[0027] Figure 10 Figure for catalytic degradation performance of Cu-BHT@Fe / Ni / Pd catalysts with different pollutant concentrations.

[0028] Figure 11 Figure for catalytic degradation performance of Cu-BHT@Fe / Ni / Pd catalysts with different catalyst dosages.

[0029] Figure 12 Figure for catalytic degradation performance of Cu-BHT@Fe / Ni / Pd catalysts in recycling experiments. DETAILED DESCRIPTION

[0030] The technical solutions of the present application will be further described below in combination with the drawings and examples.

[0031] Example 1

[0032] The embodiment adopts chemical deposition method to load iron, nickel and palladium on pretreated nickel / copper-hexathiol benzene nanoparticles under oxygen-free ultrasonic condition, and obtains a three-metal catalyst of nickel / copper-hexathiol benzene nanoparticles loaded with Fe, nickel and palladium. The preparation method comprises the following steps: step one, under nitrogen atmosphere, 0.5 mmol of hexathiol benzene and 3 mmol of CH3ONa are dissolved in 30 mL of deaerated ethanol to obtain a deprotonated hexathiol benzene solution. 10 mL of copper nitrate and nickel nitrate ethanol solution (containing 1.5 mmol of copper nitrate and 1.5 mmol of nickel nitrate) is slowly added to the hexathiol benzene solution stirred intensively by using a syringe pump. Black precipitate is rapidly generated. The obtained precipitate is filtered out, washed repeatedly with water, ethanol and acetone, and then dried in vacuum for 24 hours; step two, the nickel / copper-hexathiol benzene nanoparticles prepared in step one are ground into powder; the nickel / copper-hexathiol benzene nanoparticle powder is dissolved in anhydrous ethanol, and the nickel / copper-hexathiol benzene nanoparticles are stripped by ultrasonic cell disruptor for 16 hours. After stripping, the nickel / copper-hexathiol benzene nanoparticles and the solution are separated by suction filtration, washed with deionized water and dried to obtain nanoparticle powder of nickel / copper-hexathiol benzene; step three, the nanoparticle powder of nickel / copper-hexathiol benzene obtained in step two is dissolved in deionized water and placed in an oxygen-free environment, and then iron chloride solution is added and ultrasonically stirred for 20 minutes, and then allowed to stand for free adsorption for 30 minutes, and then excess sodium borohydride solution is added and allowed to stand for 30 minutes, and then nickel chloride solution is added and ultrasonically stirred for 30 minutes, and then palladium chloride solution is added and ultrasonically stirred for 30 minutes, so that iron, nickel and palladium are attached to the nickel / copper-hexathiol benzene nanoparticles. The molar ratio of nickel / copper-hexathiol benzene nanoparticles, iron, nickel and palladium is 10:12:0.8:0.06. The solution is filtered, washed and dried to form a catalyst.

[0033] In step one, the whole process is in an oxygen-free environment; in step two, the dispersion concentration of the nanoparticle powder of nickel / copper-hexathiol benzene in anhydrous ethanol is 1-6 mg / ml, the frequency of the ultrasonic cell disruptor is 20 kHz, the running mode is running for 8 seconds and pausing for 2 seconds, and the total running time is 16 hours. The operations involved in step three are all carried out in an oxygen-free environment, and the inert gas used in the oxygen-free environment has a purity of >99%, and is generally nitrogen or helium.

[0034] Figure 1 The X-ray diffraction pattern result shows that 2θ=44.7, 65.1 and 82.4° respectively represent the 110, 200 and 211 crystal faces of iron; 2θ=44.508, 51.847 and 76.372° respectively represent the 111, 200 and 220 crystal faces of nickel; the content of Pd in the sample is only 0.26wt% and is well dispersed, so no diffraction peak of Pd is detected.

[0035] Figures 2-3The results of the scanning electron microscope and the XPS full spectrum picture show that the sample size of the nickel / copper-6-mercaptobenzene nanoparticles which are peeled off after acid / alcohol treatment is small, and more defects appear, and Fe, Ni and Pd can be effectively loaded on the surface of the catalyst.

[0036] Experiment 1: Explore the influence of different substrate loadings of iron, nickel and palladium on the degradation of TBBPA solution; 10 mg of copper-6-mercaptobenzene nanofilm (Cu-TF), nickel / copper-6-mercaptobenzene nanofilm (Ni-TF), copper-6-mercaptobenzene nanocrystal (Cu-NC), nickel / copper-6-mercaptobenzene nanocrystal (Ni-NC), copper-6-mercaptobenzene nanoparticle (Cu-NP) and nickel / copper-6-mercaptobenzene nanoparticle (Ni-NP) are respectively loaded with iron (52.63wt%), nickel (3.51wt%) and palladium (0.13wt%) to form corresponding catalysts, 12.5 mg of each group of catalysts is added to 100 mL of TBBPA solution with an initial concentration of 10 mg / L, the initial pH of the solution is 5, and the solution is ultrasonicated, a sample is taken every interval, the reaction time t = 1 h, and the degradation effect of TBBPA is shown in Figure 4 . @ The degradation effect of TBBPA by the six groups of materials is good, and through several parallel experiments, it is found that different morphologies have a significant influence on the catalytic effect, and Ni-NP @ degrades TBBPA most rapidly, and the degradation of TBBPA is completed within 20 minutes.

[0037] Experiment 2: Explore the influence of different loadings on the degradation of TBBPA solution; iron, nickel and palladium are loaded in the form of single metal, double metal or triple metal by reduction method, 12.5 mg of the corresponding catalyst is weighed, 12.5 mg of each group of catalysts is added to 100 mL of TBBPA solution with an initial concentration of 10 mg / L, the initial pH of the solution is 5, and the solution is ultrasonicated, a sample is taken every interval, the reaction time t = 1 h, and the degradation effect of TBBPA is shown in Figure 5 . Ni-NP is loaded with iron, and the loading of the second and third metals by the reduction method can improve the catalytic effect, and the loading sequence also affects the catalytic effect, and the optimal loading sequence is iron / nickel / palladium.

[0038] Experiment 3: Explore the influence of different iron proportions on the degradation of TBBPA solution; 10 mg of Ni-NP is weighed and loaded with iron in the proportion of (35.71wt%-56.45wt%) and corresponding proportions of nickel and palladium by reduction method, 12.5 mg of the corresponding catalyst is weighed, 12.5 mg of each group of catalysts is added to 100 mL of TBBPA solution with an initial concentration of 10 mg / L, the initial pH of the solution is 5, and the solution is ultrasonicated, a sample is taken every interval, the reaction time t = 1 h, and the degradation effect of TBBPA is shown in Figure 6Increasing the iron loading from 35.71 wt% to 56.45 wt% initially improved the catalytic effect, with the best results achieved at an iron loading of 52.63 wt%. Further increasing the iron loading resulted in a corresponding decrease in catalytic effect.

[0039] Experiment 4: Exploring the effect of different nickel ratios on the degradation of TBBPA solution: 10 mg of Ni-NP was weighed and loaded with 52.63 wt% iron, 2.65 wt%-5.98 wt% nickel, and palladium in corresponding proportions using a reduction method. 12.5 mg of the corresponding catalyst was weighed and added to 100 mL of a 10 mg / L TBBPA solution with an initial pH of 5. The solution was sonicated, and samples were taken at regular intervals. The reaction time was t = 1 h. The degradation effect of TBBPA is shown in the figure. Figure 7 Increasing the iron loading from 2.65 wt% to 5.98 wt% initially improved the catalytic effect, with the best effect achieved at a nickel loading of 3.51 wt%. Further increasing the nickel loading resulted in a corresponding decrease in the catalytic effect.

[0040] Experiment 5: Exploring the effect of different palladium ratios on the degradation of TBBPA solution: 10 mg of Ni-NP was weighed and loaded with 52.63 wt% iron, 3.51 wt% nickel, and 0.026 wt%–0.26 wt% palladium via reduction. 12.5 mg of the corresponding catalyst was weighed and added to 100 mL of a 10 mg / L TBBPA solution with an initial pH of 5. The solution was sonicated, and samples were taken at regular intervals. The reaction time was t = 1 h. The degradation effect of TBBPA is shown in the figure. Figure 8 Increasing the palladium loading from 0.026 wt% to 0.26 wt% initially improved the catalytic effect, with the best effect achieved at a palladium loading of 0.13 wt%. However, further increasing the nickel loading resulted in a corresponding decrease in the catalytic effect.

[0041] Experiment 6: Exploring the effect of different pH values ​​on the degradation of TBBPA solution; 12.5 mg of trimetallic Cu-BHT@Fe / Ni / Pd was added to 100 mL of TBBPA solution with an initial concentration of 10 mg / L and an initial pH of 3-11. The solution was sonicated, and samples were taken at regular intervals. The reaction time was t = 1 h. The degradation effect of TBBPA is shown in the figure. Figure 9 . Figure 9The results of the catalytic effect comparison chart show that as the reaction time continues, TBBPA gradually decreases, and except for the PH11 group, the removal rate of 5 groups of samples can reach more than 50% within 1 h. As the reaction time continues, the reaction speed of the PH5 group is the fastest, and the removal rate can reach 99.01% in 20 minutes. The catalytic effect gradually increases from PH 3-5, gradually decreases from PH 5-11, and basically no catalytic effect can be seen in PH 11. Slightly acidic conditions can improve the catalytic effect, and too high acidic environment can corrode the surface of the catalyst and degrade the catalytic effect.

[0042] Experiment 7: Explore the economic effect of the catalyst on different concentrations of pollutants; 12.5 mg of three-metal Cu-BHT@Fe / Ni / Pd is added to 100 mL of TBBPA solution with an initial concentration of 5-40 mg / L, the initial pH of the solution is 5, and it is ultrasonically treated, a sample is taken every interval, the reaction time t = 1 h, and the degradation effect of TBBPA is shown in Figure 10 . Figure 10 The results of the catalytic degradation performance chart of different concentrations of pollutants show that as the reaction time continues, the concentration of TBBPA rapidly decreases, and the degradation rate of pollutants 5 mg / L, 10 mg / L, and 20 mg / L concentration groups to TBBPA can all reach more than 50% within 30 min. As the reaction time continues, the concentration of TBBPA rapidly decreases, and the removal rate of the catalyst to pollutants below 10 mg / L is the highest, which can reach 98% in 20 minutes.

[0043] Experiment 8: Explore the influence of catalyst dosage on the removal of TBBPA pollutants; 5-15 mg of Cu-BHT@Fe / Ni / Pd is added to 100 mL of TBBPA solution with an initial concentration of 10 mg / L, the initial pH of the solution is 5, and it is ultrasonically treated, a sample is taken every interval, the reaction time t = 1 h, and the degradation effect of TBBPA is shown in Figure 11 . Figure 11 The results of the catalytic degradation performance chart of different concentrations of pollutants show that as the reaction time continues, the concentration of TBBPA rapidly decreases, and the degradation rate of pollutants 5 mg / L, 10 mg / L, and 20 mg / L concentration groups to TBBPA can all reach more than 50% within 30 min. As the reaction time continues, the concentration of TBBPA rapidly decreases, and the removal rate of the catalyst to pollutants below 10 mg / L is the highest, which can reach 98% in 20 minutes.

[0044] Experiment 9: Explore the stability of the catalyst (cyclic experiment); 12.5 mg of three-metal Cu-BHT@Fe / Ni / Pd is added to 100 mL of TBBPA solution with an initial concentration of 10 mg / L, the initial pH of the solution is 5, and it is ultrasonically treated, a sample is taken every interval, the reaction time t = 1 h, and the degradation effect of TBBPA is shown in Figure 12 .

[0045] Further, the experimental materials and the instruments used are as follows: experimental material hexamercaptobenzene (purity≥98%), sodium methoxide (CH3ONa, analytical pure), degassed ethanol (anhydrous ethanol treated by nitrogen bubbling degassing, purity≥99.5%), copper nitrate (Cu(NO3)2•3H2O, analytical pure), nickel nitrate (Ni(NO3)2•6H2O, analytical pure), ferric chloride (FeCl3•6H2O, analytical pure), nickel chloride (NiCl2•6H2O, analytical pure), palladium chloride (PdCl2, purity≥99.9%), sodium borohydride (NaBH4, analytical pure, as reducing agent), deionized water (resistivity≥18.2MΩ•cm), tetrabromobisphenol A (TBBPA, purity≥98%, as target degradation pollutant), nitrogen (purity>99.999%), helium (purity>99.999%, standby inert gas); experimental instruments: vacuum drying oven (temperature control accuracy±1℃, vacuum degree≤10Pa), ultrasonic cell disruptor (maximum power 600W, frequency adjustable range 15-30kHz), syringe pump (flow accuracy±0.1μL / min, maximum flow 50mL / h), electric stirrer (rotation speed range 0-1500rpm, equipped with polytetrafluoroethylene stirring paddle), suction filtration device (containing 0.22μm water system filter membrane), X-ray diffractometer (XRD, CuKα target, wavelength 0.15406nm, scanning range 2θ=20-85°, step 0.02°), scanning electron microscope (SEM, acceleration voltage 0.5-30kV, resolution≤1.0nm), X-ray photoelectron spectrometer (XPS, AlKα excitation source, energy resolution≤0.5eV), pH meter (accuracy±0.01pH), ultraviolet-visible spectrophotometer (detection wavelength range 200-800nm, absorbance accuracy±0.001AU), electronic analytical balance (accuracy 0.1mg), constant temperature reaction kettle (with inert gas inlet interface, temperature control range room temperature-100℃).

Claims

1. A composite catalyst based on nickel / copper-hexamethylene hexamercaptobenzene nanoparticles supported on iron, nickel, and palladium, characterized in that, The composite catalyst uses nickel / copper-hexamethylene hexamercaptobenzene nanoparticles as a support and iron, nickel, and palladium as active components; the molar ratio of nickel / copper-hexamethylene hexamercaptobenzene nanoparticles, Fe, Ni, and Pd is 10:(9-13):(0.3-1):(0.03-0.08).

2. The composite catalyst according to claim 1, characterized in that, The composite catalyst exhibits the following X-ray diffraction characteristic peaks: characteristic diffraction peaks corresponding to the 110, 200, and 211 crystal planes of Fe appear at 2θ = 44.7°, 65.1°, and 82.4°; characteristic diffraction peaks corresponding to the 111, 200, and 220 crystal planes of Ni appear at 2θ = 44.508°, 51.847°, and 76.372°; the Pd mass fraction is 0.26 wt% and is uniformly dispersed, with no characteristic diffraction peaks of Pd. The nickel / copper-hexamercaptobenzene nanoparticles are in an exfoliated state, with a size of 40-50 nm and defective structures; Fe, Ni, and Pd are loaded on the surface of the nickel / copper-hexamercaptobenzene nanoparticles.

3. A method for preparing the composite catalyst according to claim 1, characterized in that, Includes the following steps: Step 1: Preparation of nickel / copper-hexamethylene hexamercaptobenzene nanoparticles; Step 2: Stripping nickel / copper-hexamethylene mercaptophenyl nanoparticles; Step 3: Loading Fe, Ni, and Pd active components.

4. The method for preparing the composite catalyst according to claim 3, characterized in that, The nickel / copper-hexamethylene hexamercaptobenzene nanoparticles described in step one are prepared by reacting hexamercaptobenzene, CH3ONa, copper nitrate, and nickel nitrate in a molar ratio of 0.5:(2.95~3.05):(1.45~1.55):(1.45~1.55). The specific steps include: Step S11: Under a nitrogen atmosphere with no oxygen throughout the process, hexamercaptobenzene and sodium methoxide are dissolved in degassed ethanol to obtain a deprotonated hexamercaptobenzene solution. Step S12: A copper nitrate-nickel nitrate ethanol solution is injected into a stirred deprotonated hexamercaptobenzene solution using a syringe pump, resulting in a black precipitate. Step S13: After filtering the black precipitate, wash it sequentially with water, ethanol, and acetone, and then dry it under vacuum to obtain nickel / copper-hexamercaptobenzene nanoparticles.

5. The method for preparing the composite catalyst according to claim 3, characterized in that, Step two specifically includes: Step S21: Grind the nickel / copper-hexamercaptobenzene nanoparticles obtained in step one into powder and disperse them in anhydrous ethanol at a concentration of 1-6 mg / mL. Step S22: Sonicate the dispersion; Step S23: After ultrasonication, filter and separate the particles, wash the filter residue with deionized water and dry it to obtain the stripped nickel / copper-hexamethylene mercaptophenyl nanoparticle powder.

6. The method for preparing the composite catalyst according to claim 3, characterized in that, Step three specifically includes: Step S31: Dissolve the nickel / copper-hexamethylene mercaptophenyl nanoparticle powder obtained in step two in deionized water and place it in an oxygen-free environment; Step S32: First, add ferric chloride solution, sonicate and stir, then let stand for adsorption; then add excess sodium borohydride solution and let stand. Step S33: Add nickel chloride solution and sonicate sequentially, then add palladium chloride solution and sonicate again to allow Fe, Ni, and Pd to adhere to the surface of nickel / copper-hexamercaptobenzene nanoparticles; Step S34: Finally, filter, wash, and dry to obtain the composite catalyst.

7. The method for preparing the composite catalyst according to claim 4, characterized in that, The nickel / copper-hexamethylene nanoparticles described in step one are prepared by reacting hexamethylene, CH3ONa, copper nitrate, and nickel nitrate in a molar ratio of 0.5:3:1.5:1.

5.

8. The method for preparing the composite catalyst according to claim 4, characterized in that, The temperature control accuracy of the vacuum drying in step one is 60±1℃, and the vacuum degree is ≤10Pa; the flow rate accuracy of the injection pump is 1ml / min±0.01ml / min.

9. The method for preparing the composite catalyst according to claim 6, characterized in that, In step S31, the inert gas used in the oxygen-free environment is nitrogen or helium, and the purity of the inert gas is >99%. In step S32, ferric chloride solution is added first, and the mixture is ultrasonically stirred for 15-25 minutes and then allowed to stand for adsorption for 25-35 minutes. Then, excess sodium borohydride solution is added and allowed to stand for 25-35 minutes. In step S33, nickel chloride solution is added sequentially and ultrasonically stirred for 25-35 minutes, followed by palladium chloride solution, and then ultrasonically stirred for 25-35 minutes, so that Fe, Ni, and Pd are attached to the surface of nickel / copper-hexamercaptobenzene nanoparticles.

10. The application of the composite catalyst according to any one of claims 1-2 or the composite catalyst prepared by any one of claims 3-9 in the degradation of tetrabromobisphenol A, characterized in that, include: The composite catalyst was added to a TBBPA aqueous solution with a pH of 3-5, and the catalytic degradation reaction was carried out under ultrasonic assistance and room temperature conditions.

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