CN113262786B - Heterogeneous nano copper catalyst and preparation method and application thereof - Google Patents

Abstract

The application belongs to the technical field of printed circuit board recovery, and particularly relates to a heterogeneous nano copper catalyst and a preparation method and application thereof. The application provides a heterogeneous nano-copper catalyst, including: mixing the complex copper wastewater with an adsorption carrier, and then removing a solvent of the complex copper wastewater to obtain a mixture; and calcining the mixture under the condition of protective gas to prepare the heterogeneous nano copper catalyst. This application utilizes the more active carbon adsorption PCB complex waste water of defect position to be difficult to the copper complex who gets rid of, through getting rid of behind the solvent in the complex waste water, turns into heterogeneous copper catalyst with the active carbon after adsorbing the copper complex under the high temperature calcination condition. The method greatly reduces the high cost required in the traditional method for treating the PCB complexing wastewater, solves the problems of copper recovery and ammonia nitrogen treatment in the PCB complexing wastewater, prepares products with high added values while treating the waste liquid, changes waste into valuable, saves resources, reduces the cost and creates income for enterprises.

Description

A kind of heterogeneous nano copper catalyst and its preparation method and application

technical field

The present application belongs to the technical field of printed circuit board recycling, and in particular relates to a heterogeneous nano-copper catalyst and a preparation method and application thereof.

Background technique

With the advent of the information age, the electronic industry and the information industry have gradually developed, and the related electronic industry has become one of the important pillar industries in my country, and the printed circuit board (PCB) industry, which is closely related to it, has also made rapid progress. According to the survey results of China Printed Circuit Industry Association (CPCA), there are currently more than 2,000 professional PCB manufacturers in China. In 2011, the annual output of PCB in China reached 198 million m ² , and the output value of the PCB industry was estimated to be 7.96 billion in 2004. The US dollar increased to US$32.7 billion in 2018 and is expected to reach US$40.6 billion in output value in 2023. China has become a major producer of printed circuit boards and has formed a series of industrial chains centered on printed circuit boards.

The production process of PCB reaches more than 20, and most of the processes generate waste liquid, among which the etching waste liquid is the main waste liquid in the production process. The copper content in the copper etching waste liquid is 110-160g/L, which exceeds the national discharge standard by more than 110,000 times; the ammonia nitrogen content in the alkaline etching waste liquid is 90-120g/L, which exceeds the national secondary waste liquid discharge standard by 3,600 times. above. To generate 100,000 square meters of double-sided panels (the thickness of each copper foil is 35μm), the copper content in the etching waste liquid will reach about 45,000 kg. If this waste liquid is not treated, it will not only cause serious waste, but also pollute the environment. Not in line with the concept of sustainable development. The existence of copper in copper etching wastewater is mainly complexed copper, and its complexing agents include ammonia, EDTA (ethylenediaminetetraacetic acid), citric acid and tartaric acid, etc. Due to the stability constant of the complex formed by copper and complexing agent The solubility product constant is less than that of Cu(OH) _2. If the common precipitation method (such as adding alkali to precipitate copper) is not effective, and the copper ions in the effluent are difficult to reach the standard (0.5mg/L), it is often necessary to carry out After the complexation treatment, the ionic copper can be released from the complexed copper, and then the copper in the waste liquid can be removed by coagulation and precipitation. Common breaking methods include: Na ₂ S method, heavy metal scavenger method, oxidant breaking method, iron salt "shielding" method and biochemical method. Although there are many methods for breaking the complex, it is unavoidable that additional reagents need to be added to the complex wastewater. Some of the reagents are expensive, and some of the reagents are prone to secondary pollution. Such problems undoubtedly increase the cost of waste liquid treatment. In order to realize the recycling of resources, the most reasonable way is to convert the complex wastewater into products with added value for recycling or selling.

To sum up, there are technical problems that it is difficult to recover complex copper and the treatment of ammonia nitrogen is not up to standard in the process of treating waste liquid of existing printed circuit boards.

SUMMARY OF THE INVENTION

In view of this, the present application provides a heterogeneous nano-copper catalyst and a preparation method and application thereof, which effectively solve the problems of difficulty in recovering complex copper in the existing process of treating printed circuit board waste liquid, and the problems of ammonia nitrogen treatment that does not meet the standard. technical problem.

A first aspect of the present application provides a heterogeneous nano-copper catalyst, characterized in that it includes:

Step 1. Mix the complex copper waste water with the adsorption carrier, and then adjust the pH value of the complex copper waste water to 6-7 to obtain a mixed solution;

Step 2, remove the solvent of the mixed solution, and obtain a mixture after drying;

Step 3, calcining the mixture under protective gas conditions to prepare a heterogeneous nano-copper catalyst.

Specifically, the complex copper wastewater of the present application does not need to be prepared, and is derived from the complex copper wastewater generated in the processes of "copper sinking" and "countercurrent cleaning" in the PCB double-sided manufacturing process.

In another embodiment, the adsorption carrier is selected from one or more of activated carbon, metal hydroxide, molecular sieve and ionic liquid.

In another embodiment, the adsorption carrier is selected from activated carbon.

Specifically, the heterogeneous nano-copper catalyst of the present application is a copper complex (EDTA-Cu and [Cu-(NH ₃ ) ₄ ] ²⁺ , etc.) that is difficult to remove by using activated carbon with many defects to adsorb PCB complex wastewater , by removing the solvent in the complex wastewater, the copper complex adsorbed by activated carbon is converted into a heterogeneous copper catalyst under high temperature calcination conditions, and it is applied to organic reactions.

In another embodiment, the metal hydroxide is selected from one or more of Al(OH) ₃ , Mg(OH) ₂ , Fe(OH) ₃ and hydrotalcite; the molecular sieve is selected from MCM-41 , one or more of ZSM-5, SAPO-34 and SBA-15; the ionic liquid is selected from imidazole type ionic liquid, pyridine type ionic liquid, tetramethylguanidine type ionic liquid and choline chloride type ionic liquid one or more of the liquids.

In another embodiment, the metal hydroxide is selected from Al(OH) ₃ or/and Mg(OH) ₂ ; the molecular sieve is selected from MCM-41; and the ionic liquid is selected from imidazole type ionic liquid.

In another embodiment, in step 1, the complexed copper wastewater and the adsorption carrier are stirred and mixed, and the stirring time is 1-5 h until the metal complex of the complexed copper wastewater is fully adsorbed on the adsorption carrier.

In another embodiment, the complexed copper wastewater is derived from wastewater generated in PCB production; the copper content of the complexed copper wastewater is not less than 20 mg/L; the pH of the complexed copper wastewater is less than or equal to 5.

In another embodiment, the source of the complex copper wastewater is the wastewater generated in PCB production; the copper content of the complex copper wastewater is 80 mg/L; the pH value of the complex copper wastewater is less than 5.

In another embodiment, the amount of the activated carbon is 0.5-8.0 g/L.

Specifically, the dosage of the activated carbon is 0.5-8.0g/L, the copper content of the complex copper wastewater is 80mg/L, and the copper loading range of the prepared heterogeneous nano-copper catalyst is 1wt%- 16 wt%.

In another embodiment, the calcination temperature is 500-800° C.; the calcination time is 1-4 h; and the heating rate of the calcination is 7° C./min.

Specifically, the calcination temperature is 800°C; the calcination time is 2h; and the heating rate of the calcination is 7°C/min.

Specifically, the calcination pyrolyzes the ligand framework in the complex copper wastewater to obtain a carbon-immobilized heterogeneous nano-copper solid particle catalyst with a certain arrangement order.

Specifically, in step 1, the pH value of the mixed solution is adjusted to 6-7 by adding a strong base; the strong base is an existing conventional hydroxide, such as sodium hydroxide solution.

In another embodiment, step 2 further includes collecting the solvent of the mixed solution by condensation and reflux; removing the solvent of the mixed solution by heating and evaporation, and then collecting the solvent of the mixed solution by condensation and reflux.

Specifically, the temperature of the heating and evaporation is 60-100°C.

Specifically, the solvent evaporated and removed in step 2 of the present application is collected by condensation and reflux, and can be used to prepare the electroplating solution for recycling.

In another embodiment, step 2 further includes drying the mixture for calcination; the drying temperature is 40-100° C., and the drying time is 1-5 h.

In another embodiment, the drying temperature is 50° C. and the drying time is 2 h.

In another embodiment, the protective gas in step 3 is nitrogen with a purity of 99.99% and above.

A second aspect of the present application provides a method for preparing the heterogeneous nano-copper catalyst, including:

Step 1. Mix the complex copper waste water with the adsorption carrier, and then adjust the pH value of the complex copper waste water to 6-7 to obtain a mixed solution;

Step 2, remove the solvent of the mixed solution, and obtain a mixture after drying;

Step 3, calcining the mixture under protective gas conditions to prepare a heterogeneous nano-copper catalyst.

The third aspect of the present application discloses the application of the heterogeneous nano-copper catalyst in synthetic organic matter.

In another embodiment, the heterogeneous nano-copper catalyst can participate in Cham-Lam reaction, Ullmann reaction, etc., used to realize C-X bond coupling, the reaction of synthesizing drug intermediates and pesticides, and can also be applied to copper-catalyzed coupling. in combination and reduction reactions.

When the heterogeneous nano-copper catalyst is obtained in the present application, the metal copper and ammonia nitrogen in the PCB complex copper wastewater can be fully recycled, and a cheap and easily available adsorption carrier (such as activated carbon) is used as the carrier to adsorb the copper complex therein. The copper ions are agglomerated at high temperature to prepare high value-added nano-copper catalysts, which greatly saves the cost of treating the wastewater; to a certain extent, it reduces the copper complexing produced by the PCB industry when processing printed circuit boards. The difficulty of waste water; the complex copper waste water is processed into a heterogeneous nano-copper catalyst with high added value and sold, and the solvent water of the complex copper waste water is evaporated and reused, turning waste into treasure and reducing environmental protection pressure for enterprises; The copper nano-catalyst has an adjustable loading capacity, simple operation, short steps, and saves manpower and material resources.

To sum up, the present application can recycle metal copper and ammonia nitrogen in PCB complex wastewater. On the one hand, it solves the problem of complex copper that is difficult to recover in the PCB production process, and on the other hand, it solves the problem of ammonia nitrogen treatment in this process. compliance issues.

Description of drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the accompanying drawings that are required to be used in the description of the embodiments or the prior art.

Fig. 1 is the reaction schematic diagram of step 1 in the preparation method of heterogeneous nano-copper catalyst provided by the application;

Fig. 2 is the reaction schematic diagram of step 2 in the preparation method of heterogeneous nano-copper catalyst provided by the application;

Figure 3 is the XRD characterization of the 5.0wt% PCB-Cu-C catalyst prepared in Example 2 of the application;

4 is a transmission electron microscope image of the 1.0wt% PCB-Cu-C catalyst prepared in Example 1 of the application under different magnification conditions;

5 is a transmission electron microscope image of the 1.0wt% PCB-Cu-C catalyst prepared in Example 1 of the application under different magnification conditions;

Fig. 6 is the reaction scheme of 4-methoxydiphenyl sulfide 1a provided in the embodiment of this application.

Detailed ways

The present application provides a heterogeneous nano-copper catalyst and a preparation method and application thereof, which are used to solve the technical defects of difficult to recover complex copper and substandard ammonia nitrogen treatment in the process of processing printed circuit board waste liquid in the prior art.

The technical solutions in the embodiments of the present application will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

Wherein, the reagents or raw materials used in the following examples are commercially available or homemade.

The methods of the following embodiments include:

(1) The PCB complex copper wastewater is introduced into the stirring evaporation pond, and activated carbon is added to it (the amount of activated carbon is changed according to the required heterogeneous nano-copper catalysts of different mass ratios), and the pH of the complex copper wastewater is adjusted to be 6-7, stir at room temperature for 3h (the amount of complex copper wastewater treatment increases, the stirring time also needs to be increased), so that the metal complex is fully adsorbed on the activated carbon, as shown in Figure 1;

After the stirring operation at normal temperature, the solvent is removed by heating and stirring (the solvent of the complex copper wastewater is mainly water), and the evaporated solvent is collected by condensation and reflux, which can be used to prepare an electroplating solution. drying it further;

(2) The dried mixture is placed in an inert gas atmosphere, and calcined at 500 to 800 ° C to pyrolyze the ligand skeleton in the complex wastewater to obtain a heterogeneous nano-copper catalyst (which is carbon with a certain arrangement order). immobilized nano-copper solid particles), as shown in Figure 2.

The pre-preparation method of the used PCB complex wastewater in the following examples includes:

Take the PCB complex wastewater produced by the PCB enterprise in a beaker, add 2mol/L NaOH solution dropwise to it, adjust the pH value of the solution to about 6, and the obtained solution is the PCB complex wastewater; wherein, the pre-prepared PCB complex wastewater The copper content is 80mg/L.

The heterogeneous nano-copper catalyst of the present application is abbreviated as PCB-Cu-C catalyst.

Example 1

The examples of this application provide a method for preparing a 1.0wt% PCB-Cu-C catalyst, which specifically includes:

Add 20 mL of PCB complex wastewater (copper content: 80 mg/L) and 160 mg of activated carbon into a 50 mL beaker, stir magnetically at room temperature for 30 min, and then raise the temperature to 100 °C, and remove the solvent water under magnetic stirring. After the solvent was evaporated to dryness, the catalyst was moved to a blast dryer and dried at 50°C for 2h. Then, the dried catalyst was taken out, moved to a tube furnace, and calcined under N ₂ atmosphere. The calcination conditions were: initial temperature of 30 °C, heating rate of 7 °C/min, heating to 800 °C, holding at 800 °C for 2 hours, and then cooling down. . After calcination, 152 mg of black solid powder was obtained, and a PCB-Cu-C catalyst with a mass percentage of metallic copper of 1.0 wt % was prepared.

Example 2

The examples of this application provide a method for preparing a 5.0wt% PCB-Cu-C catalyst, which specifically includes:

Add 200mL PCB complex wastewater (copper content is 80mg/L) and 320mg activated carbon into a 500mL beaker, stir magnetically at room temperature for 30min, then heat up to 100°C, and remove solvent water under magnetic stirring. After the solvent was evaporated to dryness, the catalyst was moved to a blast dryer and dried at 50°C for 2h. Then, the dried catalyst was taken out, moved to a tube furnace, and calcined under N ₂ atmosphere. . After calcination, 369 mg of black solid powder was obtained, and a PCB-Cu-C catalyst with a mass percentage of metallic copper of 5.0 wt % was prepared.

Example 3

The examples of this application provide a method for preparing a 10.0wt% PCB-Cu-C catalyst, which specifically includes:

Add 200mL PCB complex wastewater (copper content is 80mg/L) and 160mg activated carbon into a 500mL beaker, stir magnetically at room temperature for 30min, then heat up to 100°C, and remove solvent water under magnetic stirring. After the solvent was evaporated to dryness, the catalyst was moved to a blast dryer and dried at 50°C for 2h. Then, the dried catalyst was taken out, moved to a tube furnace, and calcined under N ₂ atmosphere. The calcination conditions were: initial temperature of 30 °C, heating rate of 7 °C/min, heating to 800 °C, holding at 800 °C for 2 hours, and then cooling down. . After calcination, 187 mg of black solid powder was obtained, and a PCB-Cu-C catalyst with a mass percentage of metallic copper of 10.0 wt % was prepared.

Example 4

The examples of this application are to carry out XRD characterization, electron microscope observation and functional verification of the PCB-Cu-C catalyst prepared above, including:

1. The PCB-Cu-C catalyst prepared in Example 2 was characterized by XRD. The results are shown in Figure 3. It can be seen from Figure 3 that the PCB-Cu-C catalyst prepared in the present application contains copper.

2. Electron microscope observation was carried out on the PCB-Cu-C catalyst prepared in Example 1, and the results are shown in Figures 4-5. It can be seen from Figures 4-5 that the metal complexes in the PCB-Cu-C catalyst prepared in this application are The compound was fully adsorbed on the activated carbon.

3. A functional verification test was performed on the PCB-Cu-C catalyst prepared in Example 3, including:

According to the reaction scheme of Figure 6, take a 50mL round-bottomed flask and add 0.028mg (0.2mmol) of 4-methoxythiophenol, 0.024mg (0.2mmol) of phenylboronic acid, and 0.048mg (0.4mmol) of tert-butanol to it. Potassium, 44 mg of 10 wt% PCB-Cu-C catalyst and 2 mL of DMF were used as solvents. The round-bottomed flask was moved to a magnetic stirrer and reacted at 80 °C for 12 h to obtain the product in a yield of 78.12%. The product was subjected to 1HNMR analysis and proved to be the target product 4-methoxydiphenyl sulfide 1a, the target product 4 -The 1HNMR data of methoxydiphenyl sulfide 1a are as follows:

1HNMR (400MHz, CDCl ₃ ) δ 7.42 (d, J=8.8Hz, 2H, Ar-H), 7.22 (d, J=7.4Hz, 2H, Ar-H), 7.15 (dd, J=16.0, 7.5 Hz, 3H, Ar-H), 6.90 (d, J=8.8 Hz, 2H, Ar-H), 3.82 (s, 3H, OCH ₃ ); 13C NMR (100 MHz, CDCl ₃ ) δ 135.35, 128.91, 128.21, 125.75 , 114.98, 77.32, 77.00, 76.68, 55.36, 29.69.

It can be seen that the PCB-Cu-C catalyst prepared in the examples of the present application can participate in the copper catalytic reaction.

The above are only the preferred embodiments of the present application. It should be pointed out that for those skilled in the art, without departing from the principles of the present application, several improvements and modifications can also be made. It should be regarded as the protection scope of this application.

Claims (4)

1. a preparation method of heterogeneous nano-copper catalyst, is characterized in that, comprises: Step 1. Mix the complex copper waste water with the adsorption carrier, and then adjust the pH value of the complex copper waste water to 6 to 7 to obtain a mixed solution; Step 2, remove the solvent of the mixed solution, and obtain a mixture after drying; Step 3, calcining the mixture under protective gas conditions to prepare a heterogeneous nano-copper catalyst; The protective gas is nitrogen; The calcination temperature is 500~800°C; the calcination time is 1~4h; The adsorption carrier is selected from activated carbon; The complex copper waste water is derived from waste water produced by processing printed circuit board waste liquid. 2. the preparation method of heterogeneous nano-copper catalyst according to claim 1, is characterized in that, the copper content of described complex copper waste water is not less than 20 mg/L; The pH value of described complex copper waste water is less than equals 5. 3. The preparation method of heterogeneous nano-copper catalyst according to claim 1, is characterized in that, the consumption of described activated carbon is 0.5～8.0g/L. 4. The method for preparing a heterogeneous nano-copper catalyst according to claim 1, characterized in that, in step 2, further comprising: collecting the solvent of the mixed solution by condensing and refluxing: removing the solvent of the mixed solution by heating and evaporating, The solvent of the mixture is then collected by condensing reflux.

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