CN106622303B - A kind of catalyst for catalyzing the hydrogenation reduction of nitrophenol and its application - Google Patents

Abstract

The invention relates to the technical field of nano-catalysts, in particular to a catalyst for catalyzing the hydrogenation reduction of nitrophenol and its application. The corresponding aminophenols prepared from p-nitrophenol have high catalytic activity and can be used in the reaction of catalytic reduction of nitrophenol to prepare aminophenol instead of precious metal catalysts, thereby reducing the production cost.

Description

A kind of catalyst for catalyzing the hydrogenation reduction of nitrophenol and its application

technical field

The invention relates to the technical field of nano-catalysts, in particular to a catalyst for catalyzing the hydrogenation reduction of nitrophenol and its application.

Background technique

Aminophenol is an important organic synthesis intermediate. It is generally used in the pharmaceutical industry to prepare various analgesic drugs such as paracetamol, vitamin B, antipyretic ice, and phenacetin; in the dye industry, it is generally used to prepare wood products. Colorants and hair dyes. In addition, it can also be used as photographic developer, rubber antioxidant and urea addition reaction inhibitor, etc. It is a widely used chemical raw material. Nitrophenol is a class of highly toxic, refractory, and most difficult to treat compounds. Therefore, the purification of aromatic hydrocarbon waste water is a technical problem in my country and the world. There is a need to develop economical green catalysts to reduce nitrophenols to less toxic aminophenols. Although there are many such reduction methods, only the electrolytic reduction method of nitrophenol and the catalytic hydrogenation method of nitrophenol are widely used in industrial production. The nitrophenol electrolytic reduction method has high technical requirements for the design of the reactor and the control of the process conditions, and the energy consumption is high. The catalytic hydrogenation of nitrophenol has cheap and readily available raw materials, low production cost, few steps, and good reusability. This method generally requires high-efficiency catalysts in the reduction process and can be reused.

With the rapid rise of nanotechnology, it has been widely used in the fields of catalysis, medicine, new energy and environmental protection. Due to the small size and large specific surface area of nanoparticles, the bonding state and electronic state on the surface are different from those in the particle, and the incomplete coordination of surface atoms leads to an increase in the active sites on the surface. Most of the heterogeneous catalysts currently used to catalyze the hydrogenation reduction of nitro compounds are nanocatalysts containing nanoparticles of noble metals (Ag, Au, Pd and Pt and their alloys). Although noble metal nanocatalysts have high catalytic activity, their cost is high, and they are prone to agglomeration or poisoning and deactivation during use, which reduces their catalytic efficiency. Therefore, the development of low-cost and highly efficient non-precious metal catalysts for hydrogenation and reduction of nitrophenol to aminophenol under mild conditions plays an important role in reducing industrial production costs.

SUMMARY OF THE INVENTION

In view of the deficiencies of the prior art, the present invention provides a catalyst for catalyzing the hydrogenation reduction of nitrophenol with low cost and high catalytic activity and its application.

To achieve the above purpose, the present invention is achieved through the following technical solutions:

A catalyst for catalyzing the hydrogenation reduction of nitrophenol, the catalyst is an ultra-thin nanosheet of bismuth oxychloride with a diameter of 60-80 nm, and has high performance for catalyzing reduction of ortho-, meta-, and para-nitrophenols to prepare corresponding aminophenols. catalytic activity.

The preparation method of the catalyst that catalyzes the hydrogenation reduction of nitrophenol, the steps are as follows:

1) Dissolve mannitol and polyvinylpyrrolidone (PVP, K-30) in distilled water, stir and dissolve, and prepare a 0.01mol/L mannitol aqueous solution A containing 0.15-0.20mmol/L polyvinylpyrrolidone;

2) dissolving bismuth nitrate pentahydrate in ethylene glycol, and ultrasonically forming a solution B of 0.2mol/L bismuth nitrate pentahydrate at room temperature;

3) dissolving sodium chloride in ethylene glycol, and ultrasonically forming 0.2mol/L sodium chloride solution C at room temperature;

4) Add solution B and solution C to solution A successively, stir evenly, transfer to a hydrothermal reaction kettle, seal, keep at 160-165°C for 7-8h, and cool to room temperature after the reaction;

5) Centrifuging, washing with distilled water and drying the precipitate generated in the reaction kettle to obtain a bismuth oxychloride ultra-thin nanosheet catalyst.

Preferably, the volume ratio of the solution A, the solution B, and the solution C is 6:1:1.

The application of the catalyst for catalyzing the hydrogenation reduction of nitrophenol is to ultrasonically disperse the bismuth oxychloride ultra-thin nanosheet catalyst in an aqueous solution of nitrophenol with a concentration of 0.1 mmol/L, then add sodium borohydride, and leave it to react at room temperature for 5 All nitrophenols can be hydrogenated and reduced to aminophenols in -10min. After the reaction, the catalyst can be recovered and reused.

Preferably, the mass/volume/mass ratio (g:L:g) of the catalyst, the aqueous nitrophenol solution and the sodium borohydride is 0.1-0.4:3:0.5.

Compared with the prior art, the present invention has the following beneficial effects:

1. The bismuth oxychloride (BiOCl) ultra-thin nanosheets prepared by the present invention have a diameter of 60-80nm, a thickness of about 5nm, and a specific surface area of up to 39.2m ² /g, which are used for catalytic reduction of ortho, meta, and para nitrates. The corresponding aminophenols can be prepared from aminophenols, all of which have high catalytic activity;

2. The raw materials used in the preparation of BiOCl ultra-thin nanosheets are cheap and easy to obtain, and the preparation conditions are mild and simple;

3. BiOCl ultra-thin nanosheets are used for catalytic reduction of nitrophenol to produce aminophenol. The catalytic reaction conditions are mild, the reaction is performed at room temperature and pressure, and the reaction speed is fast and easy to operate;

4. BiOCl ultra-thin nanosheet catalyst can be recycled and reused, and has good recyclability. It can replace precious metal catalysts in the reaction of catalytic reduction of nitrophenol to aminophenol to reduce costs.

Description of drawings

In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the following briefly introduces the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained according to these drawings without creative efforts.

Fig. 1 is the X-ray diffraction pattern (XRD) of the bismuth oxychloride prepared in Example 1 of the present invention;

Fig. 2 is the scanning electron microscope (SEM) of the bismuth oxychloride prepared by the embodiment of the present invention 1;

Fig. 3 is the transmission electron microscope (TEM) of the bismuth oxychloride prepared by the embodiment of the present invention 1;

4 is an atomic force microscope (AFM) and data analysis of the bismuth oxychloride prepared in Example 1 of the present invention;

5 is the nitrogen adsorption-desorption isotherm curve of bismuth oxychloride prepared in Example 1 of the present invention, and the inset is the corresponding pore size distribution curve.

Fig. 6 is the graph of bismuth oxychloride catalytic reduction of o-nitrophenol prepared in Example 2, wherein Fig. 6a is the ultraviolet-visible absorption curve diagram of catalytic reduction of o-nitrophenol; Fig. 6b is the catalytic reduction of o-nitrophenol system Graph of the change of the concentration of ortho-nitrophenol with time.

Fig. 7 is the graph of bismuth oxychloride catalytic reduction of m-nitrophenol in Example 3, wherein Fig. 7a is the UV-visible absorption curve diagram of catalytic reduction of m-nitrophenol; Fig. 7b is the catalytic reduction of m-nitrophenol system intermediate nitrophenol Graph of the change of phenol concentration with time.

Fig. 8 is the graph of the catalytic reduction of p-nitrophenol by bismuth oxychloride in Example 4, wherein Fig. 8a is the ultraviolet-visible absorption curve diagram of catalytic reduction of p-nitrophenol; Graph of nitrophenol concentration versus time.

Detailed ways

In order to make the purposes, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments These are some embodiments of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

Example 1:

Preparation of bismuth oxychloride (BiOCl) ultrathin nanosheets:

a. Dissolve 0.6 mmol of mannitol and 0.4 g of polyvinylpyrrolidone (PVP, K-30) in 60 mL of distilled water, and stir to dissolve;

b. Dissolve 2.0 mmol of bismuth nitrate pentahydrate in 10 mL of ethylene glycol, and ultrasonically form a solution at room temperature;

c. Dissolve 2.0 mmol of sodium chloride in 10 mL of ethylene glycol, and sonicate to form a solution at room temperature;

d. adding the solutions prepared in step b and step c to the solution in step a successively, and stirring uniformly to obtain a reaction solution;

e. Transfer the reaction solution in step d into a hydrothermal reaction kettle with a volume of 50 mL, then seal the hydrothermal reaction kettle, keep the temperature at 160°C for 8 h, and cool down to room temperature after the reaction is completed. Centrifugal separation, distilled water washing and drying, the BiOCl ultrathin nanosheet catalyst is obtained.

The phase of the prepared bismuth oxychloride sample was characterized by XRD. It can be seen from Figure 1 that the phase of the obtained sample is very pure and is pure tetragonal BiOCl. The morphology of the sample was characterized by SEM, TEM and AFM. It can be seen from Figure 2, Figure 3 and Figure 4 that the microscopic morphology of the prepared bismuth oxychloride is an ultra-thin nanosheet with a diameter of 50-80 nm and a thickness of about 5 nm, and the morphology and distribution are uniform.

The prepared bismuth oxychloride was tested for specific surface area and micropore distribution. It can be calculated from Figure 5 that the specific surface area of bismuth oxychloride was 39.2 m ² /g. The large specific surface area and the existence of micropores made the sample more Large adsorption and catalytic capacity.

Example 2:

Catalytic reduction of o-nitrophenol to produce o-aminophenol

a. Weigh 10 mg of bismuth oxychloride ultrathin nanosheets and disperse them in 10 mL of distilled water by ultrasonic;

b. Pipette 0.1 mL of the suspension prepared in step a and add it to 2.7 mL of o-nitrophenol aqueous solution (concentration is 0.1 mM);

c. Weigh 0.1134g of sodium borohydride and dissolve it in 10ml of ice water, pipette 0.4ml into the solution obtained in step b, mix quickly and evenly, the reaction starts;

d. Detect the absorption spectrum of the reaction solution in step c with an ultraviolet-visible spectrophotometer every 1 min, and detect the reaction process in real time until the peak at about 400 nm no longer changes significantly.

It can be seen from Figure 6a that the characteristic absorption peak of o-nitrophenol itself is at 351 nm, but after the addition of sodium borohydride, the characteristic absorption peak is red-shifted to 415 nm due to the formation of o-nitrophenolate ions under alkaline conditions , as the catalytic reaction progresses and continues, the characteristic absorption peak at 415nm gradually decreases, while a new absorption peak is generated in the range of 265-320nm and the intensity gradually increases, which is due to the conversion of o-nitrophenol ion into o-aminophenol , until the final complete conversion; Fig. 6b is the variation curve of the concentration of o-nitrophenol with time in the catalytic reaction system of Example 2, and the o-nitrophenol in the solution can be almost completely converted into o-aminophenol in only 7 minutes, reducing rate reached 95%.

Example 3:

Catalytic reduction of m-nitrophenol to m-aminophenol

a. Weigh 10 mg of bismuth oxychloride ultrathin nanosheets and disperse them in 10 mL of distilled water by ultrasonic;

b. Pipette 0.1 mL of the suspension prepared in step a and add it to 2.7 mL of m-nitrophenol aqueous solution (concentration is 0.1 mM);

c. Weigh 0.1134g of sodium borohydride and dissolve it in 10ml of ice water, pipette 0.4ml into the solution obtained in step b, mix quickly and evenly, the reaction starts;

d. Detecting the absorption spectrum of the reaction solution in step c with an ultraviolet-visible spectrophotometer, the reaction process can be detected in real time.

Fig. 7a is the ultraviolet-visible absorption spectrogram of the reaction solution in the process of catalytic reduction of m-nitrophenol to generate m-aminophenol in Example 3, the characteristic absorption peak of m-nitrophenol itself is at 350 nm, but after adding sodium borohydride, because in Under alkaline conditions, m-nitrophenate ions are formed, and the characteristic absorption peak is red-shifted to 400 nm. As the catalytic reaction progresses and continues, the characteristic absorption peak at 400 nm gradually decreases, and a new absorption peak is generated at about 300 nm and the intensity Gradually increase, this is due to the conversion of m-nitrophenol ion into m-aminophenol, until the final complete conversion; Figure 7b is the curve of the change of the concentration of intermediate nitrophenol in the catalytic reaction system of Example 3 with time, it can be seen that it only takes 2.5 minutes The m-nitrophenol in the solution can be completely converted into m-aminophenol, and the reduction rate reaches 100%.

Example 4:

Catalytic reduction of p-nitrophenol to p-aminophenol

a. Weigh 10 mg of bismuth oxychloride ultrathin nanosheets and disperse them in 10 mL of distilled water by ultrasonic;

b. Pipette 0.1 mL of the suspension prepared in step a and add it to 3.0 mL of p-nitrophenol aqueous solution (concentration is 0.1 mM);

c. Weigh 0.1134g of sodium borohydride and dissolve it in 10ml of ice water, pipette 0.4ml into the solution obtained in step b, mix quickly and evenly, the reaction starts;

d. Detecting the absorption spectrum of the reaction solution in step c with an ultraviolet-visible spectrophotometer, the reaction process can be detected in real time.

Figure 8a is the UV-Vis absorption spectrum of the reaction solution in the process of catalytic reduction of p-nitrophenol to p-aminophenol in Example 4. The characteristic absorption peak of p-nitrophenol itself is at 317 nm, but after sodium borohydride is added, it is Under alkaline conditions, p-nitrophenate ion is formed, and the characteristic absorption peak is red-shifted to 400 nm. As the catalytic reaction progresses and continues, the characteristic absorption peak at 400 nm gradually decreases, and two new absorption peaks are generated at around 233 nm and 300 nm. The absorption peak and the intensity gradually increased, which was due to the conversion of p-nitrophenol ions into p-aminophenol until the final complete conversion; Figure 8b is the curve of the change of the concentration of p-nitrophenol over time in the catalytic reaction system of Example 4. It can be seen that The p-nitrophenol in the solution can be completely converted into p-aminophenol in only 7 minutes, and the reduction rate reaches 100%.

It should be noted that, in this document, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any relationship between these entities or operations. any such actual relationship or sequence exists. Moreover, the terms "comprising", "comprising" or any other variation thereof are intended to encompass a non-exclusive inclusion such that a process, method, article or device that includes a list of elements includes not only those elements, but also includes not explicitly listed or other elements inherent to such a process, method, article or apparatus. Without further limitation, an element qualified by the phrase "comprising a..." does not preclude the presence of additional identical elements in a process, method, article or apparatus that includes the element.

The above embodiments are only used to illustrate the technical solutions of the present invention, but not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: The recorded technical solutions are modified, or some technical features thereof are equivalently replaced; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims (3)

1. the application of a catalyzer of catalyzing the hydrogenation reduction of nitrophenol, is characterized in that, described catalyzer is the bismuth oxychloride ultrathin nano-sheet of diameter at 60-80nm, to catalyzed reduction ortho, meta, p-nitrophenol system corresponding The aminophenols of bismuth oxychloride have high catalytic activity, and the catalyst is used to catalyze the reduction of o-, m-, and p-nitrophenols to prepare the corresponding aminophenols. In the nitrophenol aqueous solution of mmol/L, sodium borohydride is then added, and the reaction is allowed to stand at room temperature. All nitrophenol can be hydrogenated and reduced to aminophenol in 5-10 min. After the reaction, the catalyst can be recovered and reused. , the mass/volume/mass ratio of the aqueous solution of nitrophenol and sodium borohydride is 0.1g-0.4g: 3L: 0.5g. 2. the application of the catalyst of a kind of catalyzed nitrophenol hydrogenation reduction as claimed in claim 1, is characterized in that, the preparation method step of this catalyzer is as follows: 1) Dissolving mannitol and polyvinylpyrrolidone in distilled water, stirring and dissolving, preparing a 0.01mol/L mannitol aqueous solution A containing 0.15-0.20mmol/L polyvinylpyrrolidone; 2) dissolving bismuth nitrate pentahydrate in ethylene glycol, and ultrasonically forming a solution B of 0.2mol/L bismuth nitrate pentahydrate at room temperature; 3) dissolving sodium chloride in ethylene glycol, and ultrasonically forming 0.2mol/L sodium chloride solution C at room temperature; 4) Add solution B and solution C to solution A successively, stir evenly, transfer to a hydrothermal reaction kettle, seal, keep at 160-165°C for 7-8h, and cool to room temperature after the reaction; 5) Centrifuging, washing with distilled water and drying the precipitate generated in the reaction kettle to obtain a bismuth oxychloride ultra-thin nanosheet catalyst. 3. the application of the catalyst of a kind of catalyzing nitrophenol hydrogenation reduction as claimed in claim 2 is characterized in that, in the preparation method of this catalyzer, the volume ratio of described solution A, solution B, solution C is 6:1 :1.