A catalyst for catalyzing polymerization of aniline in water and its use

Abstract

The application relates to a catalyst for catalyzing polymerization of aniline in water and application thereof, which is obtained by calcining a mixture of a nitrogen-containing compound, copper oxide, zinc powder and selenium powder. The application has the beneficial effects that: 1, 3-dimethylurea has a unique substitution structure, methyl provides electrons, is beneficial to amino coordination, is beneficial to metal coordination, and metal utilizes the interaction with selenium powder to reduce the volatilization loss of selenium powder at high temperature, so that a unique polymer carbon nitride loaded copper-zinc-selenium catalyst is formed. In the photocatalytic aniline polymerization reaction, the excess carbon carrier in the catalyst is black, visible light absorption is strengthened, so that light energy can be fully utilized, water decomposition is promoted, hydrogen peroxide oxide is generated, aniline polymerization is carried out by oxidation, a non-hazardous polymer is formed, the preparation process of the catalyst material is very simple, the treatment of aniline wastewater is very convenient, and no acid-alkali additives and chemical oxidants are needed, so the application is more green and environment-friendly.

Description

Technical Field

[0001] This invention belongs to the fields of materials chemistry and catalysis chemistry, and specifically relates to a catalyst for catalyzing the polymerization of aniline in water and its application. Background Technology

[0002] Aniline is a toxic organic compound. In the chemical industry, wastewater containing aniline poses a significant threat to the environment and needs to be converted into non-toxic substances. Therefore, developing related technologies for environmental remediation has considerable practical value. Although aniline is toxic, its polymer, polyaniline, is non-toxic. Therefore, converting aniline into polyaniline is a remediation approach. The oxidative polymerization of aniline can produce polyaniline. Since polyaniline is a useful conductive polymer material, related technologies have been widely reported. However, existing literature focuses on the synthesis of polyaniline rather than environmental remediation. This leads to related technologies neglecting environmental requirements and widely using acid-base auxiliaries and chemical oxidants. Developing a catalytic oxidative polymerization technology for aniline that does not require acid-base auxiliaries and chemical oxidants, applicable to aniline wastewater treatment, is a technology currently needed in the chemical industry. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention provides a novel catalyst that can catalyze the oxidative polymerization of aniline in water to produce harmless polyaniline. This catalyst operates under visible light and utilizes water decomposition to generate aniline hydroperoxide, thus eliminating the need for additional chemical oxidants or acid / base additives, and has excellent practicality.

[0004] To achieve the above objectives, the present invention provides the following technical solution:

[0005] A catalyst for catalyzing the polymerization of aniline in water is obtained by calcining a mixture of nitrogen-containing compounds, copper oxide, zinc powder, and selenium powder in a mass ratio of 100:0.5-2.5:0.8-3.2:1-4 at 350-650°C.

[0006] Furthermore, the nitrogen-containing compound is selected from one of 1,3-dimethylurea, urea, thiourea, pyrimidine hydrochloride, pyrrole hydrochloride, benzamide, and 1,3-diethylurea.

[0007] Further, the nitrogen-containing compound is selected from 1,3-dimethylurea, urea, and 1,3-diethylurea; more preferably, the nitrogen-containing compound is 1,3-dimethylurea.

[0008] More preferably, the calcination temperature range is 400–600°C.

[0009] The second objective of this invention is to provide an application of the catalyst described above for the catalytic polymerization of aniline in water to treat aniline wastewater. In an aqueous aniline solution, 0.5 g / L of the catalyst is added and stirred under visible light irradiation for 2–8 h to obtain polyaniline precipitate, thereby completing the treatment of aniline wastewater.

[0010] More preferably, the visible light is an 8W blue LED.

[0011] The beneficial effects of this invention are as follows: This invention prepares a catalyst for the oxidative polymerization of aniline by calcining copper oxide, zinc powder, selenium powder, and nitrogen-containing compounds. During calcination, the nitrogen-containing compounds generate carbon nitride, and the added methyl groups increase the carbon content of the material, forming a light-absorbing carbon-based support (PCN / C). In particular, 1,3-dimethylurea, with its unique 1,3-dimethyl substitution structure (methyl group donates electrons, facilitating amino group coordination), is beneficial for metal coordination. The metal, in turn, utilizes its interaction with selenium powder to reduce the volatilization loss of selenium powder at high temperatures, thus forming a unique polymer carbon nitride-supported copper-zinc-selenium catalyst (CuZnSe@PCN / C). In the photocatalytic polymerization of aniline, the excess carbon-based support in the CuZnSe@PCN / C catalyst is black, enhancing visible light absorption, thereby fully utilizing light energy to promote water decomposition and produce hydroxide peroxide. The synergistic catalytic effect of copper and selenium promotes the polymerization of aniline by hydroxide peroxide, producing polyaniline. While the zinc powder in the catalyst does not directly participate in the catalytic oxidation reaction, it is still essential. The role of zinc powder lies in its combination with copper species, utilizing the galvanic cell effect between the two to enhance the catalytic activity of copper. Catalysts prepared under this design approach have achieved excellent results in treating aniline wastewater, requiring no additional chemical oxidants or acid / base additives, demonstrating great practicality. Attached Figure Description

[0012] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0013] Figure 1 To examine the treatment effect of aniline wastewater at different reaction times using ultraviolet-visible spectroscopy. Detailed Implementation

[0014] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0015] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0016] Example 1:

[0017] Preparation of catalyst materials:

[0018] 10 g of 1,3-dimethylurea (CAS No.: 96-31-1, purity 98%), 0.15 g of copper oxide (analytical grade), 0.2 g of zinc powder (analytical grade), and 0.25 g of selenium powder (analytical grade) were mixed evenly and then ground evenly in a large mortar to obtain a pre-calcined material. The pre-calcined material was placed in a porcelain boat in a tube furnace. Under nitrogen protection, it was heated to 500°C. After calcining at this temperature for 4 hours, it was cooled to obtain a black block. The block was ground into CuZnSe@PCN / C powder, which is the catalyst material.

[0019] application:

[0020] An aqueous solution with an aniline content of 0.01 mol / L was prepared to simulate aniline wastewater.

[0021] Add 50 mg of CuZnSe@PCN / C powder to 100 mL of aniline aqueous solution, and irradiate with 8 W LED blue light while stirring. Samples were taken at the initial reaction (0 h), 2 h, 4 h, 6 h, and 8 h for UV-Vis spectroscopy analysis. Figure 1 The degradation rate of aniline was estimated using the characteristic peak of aniline at 280 nm. By comparing the peak area with that at the beginning of the reaction, it can be deduced that approximately 83% of the aniline had polymerized after 8 hours (i.e., the aniline clearance rate was 83% after 8 hours).

[0022] Example 2:

[0023] Other conditions were the same as in Example 1, except that the amount of copper oxide added during the preparation of CuZnSe@PCN / C was changed, and the aniline removal rate was recorded after 8 hours. The experimental results are shown in Table 1.

[0024] Table 1

[0025] serial number Copper oxide dosage 8h aniline removal rate 1 0 12％ 2 0.05g 48％ 3 0.1g 70％ 4 0.15g (Example 1) 83％ 5 0.2g 74％ 6 0.25g 64％ 7 0.3g 50％

[0026] The results above show that low copper oxide content results in insufficient catalytic centers, leading to decreased catalyst activity. Excessive copper oxide content, on the other hand, can mask selenium catalytic sites, preventing the formation of a synergistic catalytic mechanism and also causing a decrease in catalyst activity. The material prepared with 1.5% copper oxide as the concentration of 1,3-dimethylurea exhibits the highest catalytic activity and best performance.

[0027] Example 3:

[0028] Other conditions were the same as in Example 1, except that the amount of zinc powder added during the preparation of CuZnSe@PCN / C was changed, and the aniline removal rate was recorded after 8 hours. The experimental results are shown in Table 2.

[0029] Table 2

[0030] serial number Zinc powder dosage 8h aniline removal rate 1 0 22％ 2 0.08g 47％ 3 0.12g 58％ 4 0.16g 76％ 5 0.2g (Example 1) 83％ 6 0.24g 78％ 7 0.28g 72％ 8 0.32g 67％ 9 0.36g 58％

[0031] The role of zinc powder is to combine with copper species, utilizing the galvanic cell effect between them to enhance the catalytic activity of copper. The results show that the optimal zinc powder concentration (2.0% of 1,3-dimethylurea) yields the best results. At this ratio, the interaction between zinc powder and copper species promotes the catalytic activity of copper. Lower concentrations are less effective, while higher concentrations result in excessively strong reducing properties, causing all copper oxide to be reduced to elemental form, thus losing its catalytic activity.

[0032] Example 4:

[0033] Other conditions were the same as in Example 1, except that the amount of selenium powder added during the preparation of CuZnSe@PCN / C was changed, and the aniline removal rate was recorded after 8 hours. The experimental results are shown in Table 3.

[0034] Table 3

[0035]

[0036]

[0037] The results above show that the optimal effect is achieved when the selenium powder content is 2.5% of 1,3-dimethylurea. Theoretically, the molar ratio of selenium to copper for synergistic catalysis should be 1:1. Copper oxide has a molecular weight of 80, while selenium has 79, which are comparable. Therefore, theoretically, the best result is when the selenium powder mass is the same as that of copper. However, since selenium is lost through volatilization during calcination, the dosage needs to be increased. Therefore, the optimal selenium powder content (2.5%) is slightly higher than that of copper oxide (1.5%).

[0038] Example 5:

[0039] Other conditions were the same as in Example 1, except that the calcination temperature was changed and the aniline removal rate was recorded after 8 hours. The experimental results are shown in Table 4.

[0040] Table 4

[0041] serial number Calcination temperature 8h aniline removal rate 1 350℃ 43％ 2 400℃ 70％ 3 450℃ 80％ 4 500℃ (Example 1) 83％ 5 550℃ 78％ 6 600℃ 67％ 7 650℃ 22％

[0042] As shown in the table above, the optimal calcination temperature is 500℃. At this temperature, the active components can be fully melted, while avoiding the loss of active species due to excessively high temperatures.

[0043] Example 6:

[0044] With other conditions unchanged, other nitrogen-containing compounds were used to replace 1,3-dimethylurea to prepare the material, and the scavenging rate of aniline was recorded after 8 hours. The results are shown in Table 5.

[0045] Table 5

[0046] serial number Nitrogen compounds 8h aniline removal rate 1 1,3-Dimethylurea (Example 1) 83％ 2 urea 51％ 3 Thiourea 35％ 4 Pyrimidine (hydrochloride) 32％ 5 Pyrrole (hydrochloride) 24％ 6 benzamide <10％ 7 1,3-Diethylurea 65％

[0047] As mentioned above, when using other nitrogen-containing compounds to prepare materials, the catalyst materials prepared from urea and 1,3-diethylurea can achieve a removal rate of over 50% for aniline after 8 hours. Relatively speaking, 1,3-dimethylurea achieves the most satisfactory effect, which is related to its unique structure. During calcination, 1,3-dimethylurea regenerates carbon nitride, and the added methyl groups can increase the carbon content in the material, forming a light-absorbing carbon-based support (PCN / C). Furthermore, its unique 1,3-dimethyl substitution structure (methyl groups donate electrons, facilitating amino group coordination) is beneficial for metal coordination. In addition, it is worth mentioning that the inventors discovered in numerous experiments that direct calcination of selenium powder and zinc powder is prone to explosion. However, after incorporating 1,3-dimethylurea, the coordination force between this substance and zinc weakens the activity of zinc powder, making its reaction with selenium powder less violent and reducing the risk of explosion.

[0048] In summary, after extensive experimental verification, this application found that a catalyst material for the polymerization of aniline in water to form a non-toxic polymer can be obtained by calcining a mixture of 1,3-dimethylurea, copper oxide, zinc powder, and selenium powder. The process of preparing the catalyst material is very simple, the treatment of aniline wastewater is also very convenient, and no acid or alkali additives or chemical oxidants are required, making it more green and environmentally friendly.

[0049] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A catalyst for catalyzing the polymerization of aniline in water, characterized in that, It is obtained by calcining a mixture of nitrogen-containing compound, copper oxide, zinc powder and selenium powder in a mass ratio of 100:0.5~2.5:0.8~3.2:1~4 at 350~650℃; the nitrogen-containing compound is selected from one of 1,3-dimethylurea, urea, thiourea, pyrimidine hydrochloride, pyrrole hydrochloride and 1,3-diethylurea.

2. The catalyst for catalyzing the polymerization of aniline in water according to claim 1, characterized in that, The nitrogen-containing compound is 1,3-dimethylurea.

3. The catalyst for catalyzing the polymerization of aniline in water according to claim 1, characterized in that, The calcination temperature range is 400~600℃.

4. The application of the catalyst according to any one of claims 1 to 3 in catalyzing the polymerization of aniline in water to treat aniline wastewater, characterized in that, Add 0.5 g / L of catalyst to an aqueous aniline solution and stir under visible light for 2-8 hours to obtain polyaniline precipitate, thus completing the treatment of aniline wastewater.

5. The application according to claim 4, characterized in that, The visible light source is an 8W blue LED.

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