A method for synthesizing a foam nickel supported copper cobalt oxide catalyst

Abstract

The application belongs to the technical field of catalyst synthesis, and discloses a method for synthesizing a foam nickel loaded copper cobalt oxide catalyst, wherein CuCl2.2H2O and CoCl2.6H2O are used as copper sources and cobalt sources, the copper cobalt ratio is 7:3, foam nickel is used as a carrier, and Cu7Co3 / NF 500℃ oxide is synthesized at an annealing temperature of 500 DEG C. The catalyst is characterized by SEM, and has a structure of bristle-shaped nanoparticles. The catalyst can effectively accelerate the reduction reaction of 4-NP and reduce 4-NP into 4-AP. During the use of the catalyst for 5 cycles, the catalytic effect gradually increases and then stabilizes. After 5 cycles, the morphology of the catalyst is characterized by SEM, and the morphology is still a bristle-shaped structure. The application provides a stable, efficient and recyclable organic pollutant catalyst and a manufacturing method thereof, and the catalyst is suitable for being used as a catalyst for 4-NP reduction reaction.

Description

Technical Field

[0001] This invention relates to the field of catalyst synthesis technology, and in particular to a method for synthesizing a catalyst using nickel foam supported on copper-cobalt oxide. Background Technology

[0002] p-Nitrophenol (4-NP) is a structurally stable, difficult-to-treat, and highly toxic organic pollutant, posing a significant hazard. Therefore, the utilization and purification of wastewater containing 4-NP has become a research hotspot. Currently, various degradation methods have been developed for treating 4-NP wastewater, such as physical methods, microbial degradation methods, and chemical treatment methods. Among these, chemical reduction is widely used in treating phenol-containing wastewater. Through experiments and research, it has been found that hydrogenation reduction using NaBH4 as a hydrogen source has mild reaction conditions, is simple to operate, and can simultaneously reduce pollutants to obtain useful 4-AP products. This process is green, environmentally friendly, economical, and simple to operate. However, the reaction has kinetic limitations, requiring the addition of a catalyst to accelerate the reaction.

[0003] Nickel foam (NF) is an open-cell metal foam composed of numerous interconnected pores. It is typically prepared by immersing a nickel plate in a solution containing a foaming agent and reacting the resulting solution at high temperatures. Due to its porous structure, nickel foam exhibits excellent permeability and catalytic activity, along with good biocompatibility, resistance to acid and alkali corrosion, and low density, making it suitable as a catalyst support.

[0004] In the reduction of 4-NP reactions, noble metal catalysts and non-noble metal catalysts are commonly used. Noble metal catalysts usually have high activity, but their application is limited by high cost, low abundance, and complex and cumbersome synthesis conditions. Non-noble metal catalysts, due to their large reserves, low cost, and good catalytic activity, have gradually become one of the frontier fields of chemical synthesis as highly active hydrogenation catalysts. At present, non-noble metal catalysts mainly focus on non-noble 3d transition metals such as Cu, Co, Ni, and Fe and their oxides. Cu-Co bimetallic catalysts are one such example. However, CuCo-based catalysts still have some problems, such as the need for template agents, long preparation time, high reaction temperature, and large particle size and wide distribution. Therefore, there is a need to develop a small-sized, uniform, highly dispersed CuCo bimetallic catalyst with a simple preparation process and good stability. Summary of the Invention

[0005] The present invention aims to provide a method for synthesizing a catalyst with nickel foam supported on copper cobalt oxide, so as to obtain a small-sized, uniform, highly dispersed CuCo dual transition metal catalyst with simple preparation process and good stability, which can be used for the catalytic reduction of 4-NP reaction.

[0006] The catalyst of this invention is a Cu7Co3 / NF catalyst prepared using CuCl2·2H2O as the copper source and CoCl2·6H2O as the cobalt source, with a CuCo ratio of 7:3, at an annealing temperature of 500°C. 500℃ The oxide catalyst has a morphological structure of burr-like nanoparticles.

[0007] The preparation process of a synthesis catalyst for nickel foam supported on copper-cobalt oxide according to the present invention includes the following steps:

[0008] (1) Treat 36 pieces of nickel foam (5×8mm) with hydrochloric acid, wash with deionized water after 1 hour, and dry the separated nickel foam in an oven at 100°C for 1 hour for later use.

[0009] (2) Based on a total amount of 0.6 mmol of CuCl2·2H2O and CoCl2·6H2O, the amount of copper source CuCl2 used was calculated to be 71.6 mg and the amount of cobalt source CoCl2 used was 42.83 mg according to a ratio of 7:3.

[0010] (3) After weighing the appropriate amounts of copper and cobalt sources, dissolve the medicine and nickel foam in 50 ml of deionized water, place it in a three-necked flask, and use a stirrer to stir and heat to 80°C at a speed of 500 r / min, and keep it warm for 1 hour for later use.

[0011] (4) After the three-necked flask is cooled, remove it, wash the medicine, put it in an oven at 100°C for 2 hours, and then take it out and cool it to room temperature.

[0012] (5) Place the nickel foam in a muffle furnace and heat it to 500°C in air at a heating rate of 3.6°C / min. Hold it at 500°C for 1 hour and remove it after cooling to room temperature.

[0013] Compared with the prior art, the present invention has the following advantages:

[0014] (1) The catalyst uses nickel foam as a support. Using nickel foam as a support can obtain a large specific surface area. The pore structure of nickel foam gives it a large specific surface area, which can provide more active sites, thereby enhancing the activity and selectivity of the catalyst. Nickel foam has good heat transfer performance and high stability, can withstand high temperature reactions, and is not easy to sinter or deactivate. The pore size and distribution of nickel foam can be controlled by different preparation methods and control conditions to adapt to different reaction needs. Nickel foam has low cost and can be produced on a large scale.

[0015] (2) This catalyst is a CuCo dual transition metal catalyst. Cu-based and Co-based catalysts are characterized by high activity, high abundance, and low cost. Furthermore, their variable oxidation states can effectively catalyze reactions involving electron transfer via single and double electron pathways. +-Cu 2+ and Co 2+ -Co + Valence state changes between ions can improve catalytic activity, and bimetallic doping can produce a synergistic effect, thereby improving catalyst performance.

[0016] (3) The CuCo ratio of the catalyst is 7:3. Under this ratio, its morphology can be characterized by SEM to obtain nanoparticles with a burr-like structure. This high curvature protrusion structure can simulate the edges or corners in nanoparticles and improve its catalytic activity.

[0017] (4) After multiple catalytic uses, the morphology and structure of the catalyst have not changed significantly and still have a burr-like structure. The conversion rate can still reach more than 97% after multiple cycles.

[0018] (5) The preparation process of this catalyst is simple and convenient, and the cost of its raw materials is also low. It can be prepared in experiments. Attached Figure Description

[0019] Figure 1 These are SEM images of CuCo / NF with different copper-cobalt ratios in Example 1 of this invention.

[0020] Figure 2 This is a SEM image of Cu7Co3 / NF in Example 1 of the present invention;

[0021] Figure 3 These are SEM images of Cu7Co3 / NF at different annealing temperatures in Example 2 of this invention;

[0022] Figure 4 The UV-Vis spectrum changes and ln(A) of the reaction after adding Cu7Co3 / NF catalyst at 500℃ in Example 3 of this invention are shown. t / A0) and reaction fitting plot.

[0023] Figures 5-9 The UV-Vis and kapp plots for five cycles in Embodiment 3 of the present invention;

[0024] Figure 10 This is a SEM image of the Cu7Co3 / NF500℃ oxide after five cycles in Example 3 of the present invention. Detailed Implementation

[0025] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments:

[0026] Example 1:

[0027] Catalysts were prepared using different proportions of copper and cobalt sources:

[0028] (1) Treat 36 pieces of nickel foam (5×8mm) with hydrochloric acid, wash with deionized water after 1 hour, and dry the separated nickel foam in an oven at 100°C for 1 hour for later use. This is one set of nickel foam required. Make a total of 11 sets and repeat the above operation 11 times.

[0029] (2) Using a total of 0.6 mmol of CuCl2·2H2O and CoCl2·6H2O, the amounts of copper and cobalt sources were calculated according to different ratios (10:0, 9:1, 8:2, 7:3, 6:4, 5:5, 4:6, 3:7, 2:8, 1:9, 0:10), resulting in 11 groups. The application amounts are shown in Table 1.

[0030] Table 1

[0031]

[0032] (3) Weigh the appropriate amounts of copper and cobalt sources, then dissolve the medicine and nickel foam in 50 ml of deionized water, place it in a three-necked flask, and place it on a stirrer to heat to 80°C at a speed of 500 r / min, and keep it warm for one hour for later use.

[0033] (4) After the three-necked flask has cooled down, remove it, wash the medicine, put it in an oven at 100°C to dry, and take it out and cool it to room temperature after 2 hours.

[0034] (5) Place the nickel foam in a muffle furnace and heat it to 500°C in air at a heating rate of 3.6°C / min, and hold it at 500°C for 1 hour. After cooling to room temperature, remove it and name it CuCo / NF.

[0035] The above process yielded 11 groups of CuCo / NF oxides.

[0036] Then, these 11 groups of CuCo / NF oxides were used as catalysts for the 4-NP reduction experiment. 10 μL of a 10 mmol / L 4-NP solution, 200 μL of freshly prepared 0.1 mol / L NaBH4 solution, and 2 mL of ultrapure water were added to a centrifuge tube. Two pieces of prepared nickel foam samples were then added. Timing began when the nickel foam was added and continued until the solution color changed from pale yellow to colorless. This process was repeated eleven times, and the catalytic time for each group was recorded. The experimental times for the CuCo / NF catalytic reduction of 4-NP are shown in Table 2.

[0037] Table 2

[0038]

[0039] In this experiment, the reaction conditions and the amount of catalyst were all the same. The only variable in each group of reactions was the copper-cobalt ratio. According to the experimental data, the 4-NP reduction time was the shortest and the catalytic effect was the best when the copper-cobalt ratio was 7:3.

[0040] The morphology of these 11 groups of samples was analyzed using field emission scanning electron microscopy (SEM), such as... Figure 1 As shown.

[0041] Depend on Figure 1 It can be seen that when the CuCo ratio is 7:3, the CuCo / NF oxide exhibits the best morphology, appearing as burr-like particles, such as... Figure 2 As shown.

[0042] In summary, Cu7Co3 / NF oxide exhibits good morphology, large specific surface area, and the best catalytic effect.

[0043] Example 2:

[0044] Based on Example 1, catalysts were prepared using different annealing temperatures:

[0045] The catalyst was prepared using an optimal copper-cobalt ratio of 7:3. In step 4 of the preparation process in Example 1, four groups of Cu7Co3 / NF oxides were prepared by setting different annealing temperatures of 200, 300, 400, and 500°C.

[0046] Then, these four groups of CuCo / NF oxides were used as catalysts for 4-NP reduction experiments. The experimental procedure was the same as that in Example 1. The experimental times for the catalytic reduction of 4-NP by Cu7Co3 / NF oxides are shown in Table 3.

[0047] Table 3

[0048]

[0049] Table 3 shows that 500℃ is the optimal annealing temperature for Cu7Co3 / NF oxide, and its catalytic performance is the best.

[0050] The morphology of these four groups of samples was analyzed using field emission scanning electron microscopy (SEM), such as... Figure 3 As shown.

[0051] Depend on Figure 3 It can be seen that at 200℃, the catalyst morphology is large-sized solid octahedral nanoparticles; at 300℃, the morphology is solid octahedral nanoparticles with both large and small sizes, and some loose nanostructures also exist; at 400℃, the morphology is a packed loose structure; and at 500℃, the morphology is a small-sized uniform burr structure.

[0052] In conclusion, Cu7Co3 / NF500℃ is the best catalytic sample synthesized from these samples.

[0053] Example 3:

[0054] The Cu7Co3 / NF500℃ oxide exhibited excellent catalytic performance in morphology analysis and catalytic experiments. Therefore, taking this sample as an example, a 5×8mm piece of nickel foam was added to the 4-NP reaction solution, and the reaction was detected using a UV-Vis spectrophotometer. Figure 4 As shown in (a), Figure 4 (a) The UV-Vis absorption spectrum of 4-NP added to NaBH4 solution shows that the absorption peak at 400 nm gradually decreases over time, and the new peak at 300 nm corresponds to the absorption peak of 4-AP, indicating that 4-NP is reduced to 4-AP in about 11 min.

[0055] In the reaction system, BH4 is produced by the ionization of NaBH4. - Ions act as electron and hydrogen donors. When Cu7Co3 / NF500℃ oxide is added to the solution, 4-NP and BH4 in the aqueous medium... - Ions are adsorbed on the surface of Cu7Co3 / NF500℃ nanomaterials. The Cu7Co3 / NF500℃ material acts as an intermediate, transferring electrons from the donor BH4. - Transfer to the receptor 4-NP overcomes the kinetic barrier of the reaction, leading to the formation of 4-AP. In BH4 - In the presence of anions, Cu 2+ It can be easily converted into Cu + Cu in Cu7Co3 / NF500℃ oxide + -Cu 2+ and Co 2+ -Co + The change in valence state between ion pairs can improve catalytic activity, which is a significant advantage over other materials.

[0056] In this study, because the concentration of NaBH4 was much higher than that of the reactant (4-NP), the catalytic reaction followed pseudo-first-order kinetics. Therefore, the kinetics of 4-NP reduction can be expressed by a linear equation: -kt=ln(C t / C0)=ln(A t / A0), where A t A0 represents the absorbance value in certain stages and the initial stage, such as... Figure 4 As shown in (b), its apparent rate constant kapp is 6 × 10⁻⁶. -3 S -1 .

[0057] Testing the cycling performance of Cu7Co3 / NF at 500℃:

[0058] After the first 4-NP reduction reaction, the Cu7Co3 / NF 500℃ sample was removed, cleaned, and the 4-NP reduction reaction was repeated five times. The catalytic time and catalyst performance were characterized for each reaction. See Table 4 for details.

[0059] Table 4

[0060]

[0061] The five reactions were detected using a UV-Vis spectrophotometer, such as Figures 5-10 As shown.

[0062] Depend on Figures 4-9 It can be concluded that Cu7Co3 / NF, as a nanocatalyst at 500℃, exhibits excellent stability and reusability. In the initial reaction, after the addition of the catalyst, 4-NP was completely degraded within 10 minutes, as shown in the figure. Figure 4 As shown in (a), the time was 560s. During the cycle test, the time stabilized at around 350s, which was faster than the first catalytic reaction. Therefore, it is believed that the catalyst needs to be activated. After the catalyst activity is activated, its catalytic performance is better, and it can convert 4-NP to 4-AP within 6 minutes. Its kapp apparent rate constant also increases accordingly, to about 12 × 10⁻⁶. -3 S -1 .

[0063] Finally, the Cu7Co3 / NF oxidized sample after 5 cycles at 500℃ was characterized by SEM, and its SEM morphology is as follows: Figure 10 As shown. By Figure 10 It can be seen that its morphology has not changed significantly compared with that before the reaction, and the burr-like structure still exists, indicating that Cu7Co3 / NF500℃ can be used as a stable, efficient and recyclable organic pollutant catalyst.

[0064] The above descriptions are merely embodiments of the present invention, and common knowledge regarding specific technical solutions or characteristics is not elaborated upon here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the technical solutions of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A catalyst for the synthesis of nickel foam supported on copper-cobalt oxide, characterized in that: The catalyst is a Cu7Co3 / NF catalyst prepared at a Cu:Co ratio of 7:3 and an annealing temperature of 500℃. 500℃ Oxides; the preparation process includes the following steps: (1) Treat 36 pieces of nickel foam with hydrochloric acid, wash with deionized water after 1 hour, and dry the separated nickel foam in an oven at 100°C for 1 hour for later use. (2) Based on the total amount of 0.6 mmol of CuCl2•2H2O and CoCl2•6H2O, calculated in a ratio of 7:3, the amount of copper source CuCl2 used is 71.6 mg and the amount of cobalt source CoCl2 used is 42.83 mg; (3) After weighing the corresponding amounts of copper source and cobalt source, dissolve the medicine and foamed nickel in 50 ml of deionized water, place it in a three-necked flask, and use a stirrer to stir and heat to 80°C at a speed of 500 r / min, and keep it warm for 1 hour for later use. (4) After the three-necked flask has cooled, remove it, wash the medicine, put it in an oven at 100°C for 2 hours, and then take it out and cool it to room temperature. (5) Place the nickel foam in a muffle furnace and heat it to 500°C in air at a heating rate of 3.6°C / min. Hold it at 500°C for 1 hour and remove it after cooling to room temperature.

Images