阅读说明：本技术 一种mof-5基微孔碳催化剂的制备方法及用途 (Preparation method and application of MOF-5-based microporous carbon catalyst ) 是由 向柏霖 李元祥 陈桂 王飘 于 2019-11-21 设计创作，主要内容包括：本发明公开了一种MOF-5基微孔碳催化剂的制备方法及用途,本发明以MOF-5为模板,通过在氮气氛围下高温碳化后得到含氧化锌的多孔碳,再经酸洗除去氧化锌,得到微孔碳,再将催化活性位负载到多孔碳上,得到催化剂,用于苯酚羟基化反应,制作简单且产量高。(The invention discloses a preparation method and application of an MOF-5-based microporous carbon catalyst, wherein MOF-5 is used as a template, porous carbon containing zinc oxide is obtained by high-temperature carbonization in a nitrogen atmosphere, then the zinc oxide is removed by acid washing to obtain microporous carbon, and a catalytic active site is loaded on the porous carbon to obtain the catalyst for a phenol hydroxylation reaction, so that the catalyst is simple to prepare and high in yield.)

1. A preparation method of the MOF-5-based microporous carbon catalyst is characterized by comprising the following steps:

step one, taking Zn (NO)₃)₂·6H₂Adding O and terephthalic acid into DMF (dimethyl formamide), stirring at room temperature to dissolve to obtain a clear solution, then dropwise adding triethylamine under stirring, gradually becoming turbid, continuously stirring for 1-3h after dropwise adding, vacuumizing and filtering to obtain a filter cake, washing the filter cake with DMF, and then drying at high temperature to obtain an MOF-5 carrier;

step two, putting the MOF-5 carrier into a tube furnace, heating to 500-800 ℃ in a nitrogen atmosphere, then preserving heat for 1-4 hours, and cooling to room temperature to obtain a product 1; then, the product 1 is subjected to acid washing and pure water washing, zinc oxide is removed through dissolution, a generated carbon sample is dried, and the microporous carbon material MDPC-600 is obtained;

step three, weighing MDPC-600, and then weighing a transition metal ion salt, wherein the transition metal ion accounts for 0.5% -8% of the mass of the MDPC-600; adding the weighed transition metal ion salt into absolute ethyl alcohol, then adding MDPC-600 powder, and completely soaking the added MDPC-600 powder by an ethanol solvent; fully mixing and drying to obtain the MOF-5 based microporous carbon catalyst.

2. The method of making a MOF-5 based microporous carbon catalyst of claim 1, wherein in step one, Zn (NO)₃)₂·6H₂The mass ratio of O to terephthalic acid is 1:0.2-1: 1; zn (NO)₃)₂·6H₂The mass ratio of O to DMF is 1:30-1: 60; zn (NO)₃)₂·6H₂The mass ratio of O to triethylamine is 1:0.5-1: 2; in the first step, the filter cake is washed with DMF for 2 times, and the MOF-5 carrier is obtained after drying at 120 ℃.

3. The method of making a MOF-5 based microporous carbon catalyst of claim 1, wherein the metal ion is Fe³⁺(ii) a The MOF-5-based microporous carbon catalyst is an Fe (III)/MDPC-600 catalyst.

4. The method for preparing the MOF-5 based microporous carbon catalyst according to claim 1, wherein in the second step, the heating rate is 6-12 ℃/min, and the nitrogen flow rate is 100-200 mL/min.

5. The method of making a MOF-5 based microporous carbon catalyst according to claim 1, wherein in step two, the acid is washed three times and the pure water is washed two times; the acid solution used for acid washing is dilute hydrochloric acid, dilute nitric acid or dilute sulfuric acid.

6. A method of making a MOF-5 based microporous carbon catalyst according to claim 1, wherein in step two, the temperature at which the carbon sample is dried is 120 ℃.

7. The method of making a MOF-5 based microporous carbon catalyst of claim 1, wherein in step three, the absolute ethanol is the same volume as MDPC-600; and dried at 90 ℃ for 2h to obtain the Fe (III)/MDPC-600 catalyst.

8. Use of a MOF-5 based microporous carbon catalyst according to any one of claims 1 to 7 for hydroxylation of phenol.

9. Use of a MOF-5 based microporous carbon catalyst according to claim 8, by the following method:

weighing an MOF-5-based microporous carbon catalyst, phenol, 30% hydrogen peroxide and deionized water, mixing in a round-bottom flask, reacting for 1-4h under the condition of magnetic stirring at the temperature of 70-90 ℃, filtering after the reaction is finished, extracting the filtrate for three times by using an extraction solvent, and analyzing the content of phenol and benzenediol in the extract by using a gas chromatograph-mass spectrometer; the mass ratio of the MOF-5-based microporous carbon catalyst to the phenol is 1:10-1: 50; the volume ratio of the phenol to the hydrogen peroxide is 1:1-1: 20; the volume ratio of the phenol to the deionized water is 1:20-1: 60.

10. Use of a MOF-5 based microporous carbon catalyst according to claim 8 wherein the extraction solvent is at least one of ethyl acetate, chloroform and carbon tetrachloride.

The technical field is as follows:

the invention relates to the field of chemistry, in particular to a preparation method and application of an MOF-5-based microporous carbon catalyst.

Background art:

carbon materials have been found to be useful in heterogeneous catalysis. They can be used both as catalysts and as supports for other catalytically active phases. The surface chemistry of carbon materials can be ascribed to surface oxygen-containing groups, which can be acidic, basic or neutral. The interaction between the surface groups and the active phase also produces a synergistic effect on the catalytic activity of these materials. However, if the surface area and porosity of the carbon material are increased, it is helpful to improve the dispersibility of the active phase in the carbon material, thereby improving its catalytic activity.

Metal-organic frameworks (MOFs) are crystalline porous materials obtained by coordination of metal ions and organic ligands, have a regular structure and adjustable pore size, and have been widely used in research in the fields of gas separation, heterogeneous catalysis, sensing, drug delivery and the like for nearly 20 years due to their excellent physicochemical properties, and are considered to be very potential catalyst materials particularly due to their porosity and good dispersibility. In recent years, as the MOFs have various structures and the pore size can be adjusted by design, the MOFs are widely used as template materials to prepare porous materials or porous carbon materials rich in metal oxides or simple substances, and a series of porous materials with special structures and properties are obtained. Of particular interest is the carbonization of MOFs, which contain organic ligands and do not require additional major carbon sources. According to the selected metal and organic linking agent, networks with various pore diameters, shapes and volumes can be controlled and synthesized, porous carbon obtained from the MOFs without any modification has uniform porosity, and therefore, the MOFs are carbonized to obtain microporous carbon Materials (MDPC) with huge specific surface areas. The microporous carbon material has great specific surface area, low solubility and high chemical stability, so that the microporous carbon material is a promising catalyst carrier material and is widely used for preparing various catalysts.

The invention content is as follows:

the invention aims to provide a preparation method and application of an MOF-5-based microporous carbon catalyst, wherein MOF-5 is used as a template, porous carbon containing zinc oxide is obtained by high-temperature carbonization in a nitrogen atmosphere, then the zinc oxide is removed by acid washing to obtain microporous carbon, and a catalytic active site is loaded on the porous carbon to obtain the catalyst for a phenol hydroxylation reaction.

In order to solve the problems, the technical scheme of the invention is as follows:

a preparation method of the MOF-5-based microporous carbon catalyst comprises the following steps:

step one, taking Zn (NO)₃)₂·6H₂Adding O and terephthalic acid into DMF (dimethyl formamide), stirring at room temperature to dissolve to obtain a clear solution, then dropwise adding triethylamine under stirring, gradually becoming turbid, continuously stirring for 1-3h after dropwise adding, vacuumizing and filtering to obtain a filter cake, washing the filter cake with DMF, and then drying at high temperature to obtain an MOF-5 carrier;

step two, putting the MOF-5 carrier into a tube furnace, heating to 500-800 ℃ in a nitrogen atmosphere, then preserving heat for 1-4 hours, and cooling to room temperature to obtain a product 1; then, the product 1 is subjected to acid washing and pure water washing, zinc oxide is removed through dissolution, a generated carbon sample is dried, and the microporous carbon material MDPC-600 is obtained;

step three, weighing MDPC-600, and then weighing a transition metal ion salt, wherein the transition metal ion accounts for 0.5% -8% of the mass of the MDPC-600; adding the weighed transition metal ion salt into absolute ethyl alcohol, then adding MDPC-600 powder, and completely soaking the added MDPC-600 powder by an ethanol solvent; fully mixing and drying to obtain the MOF-5 based microporous carbon catalyst.

In a further improvement, in step one, Zn (NO)₃)₂·6H₂The mass ratio of O to terephthalic acid is 1:0.2-1: 1; zn (NO)₃)₂·6H₂The mass ratio of O to DMF is 1:30-1: 60; zn (NO)₃)₂·6H₂The mass ratio of O to triethylamine is 1:0.5-1: 2; in the first step, the filter cake is washed with DMF for 2 times, and the MOF-5 carrier is obtained after drying at 120 ℃.

In a further improvement, the metal ion is Fe³⁺(ii) a The MOF-5-based microporous carbon catalyst is an Fe (III)/MDPC-600 catalyst.

In the step one, the filter cake is washed 2 times by DMF, and the MOF-5 carrier is obtained after drying at 120 ℃.

In the second step, the heating speed is 6-12 ℃/min, and the nitrogen flow is 100-200 mL/min.

In the second step, acid washing is carried out for three times, and pure water washing is carried out for two times; the acid solution used for acid washing is dilute hydrochloric acid, dilute nitric acid or dilute sulfuric acid.

In a further improvement, in the second step, the temperature for drying the carbon sample is 120 ℃.

In a further improvement, in the third step, the volume of the absolute ethyl alcohol is the same as that of the MDPC-600; and dried at 90 ℃ for 2h to obtain the Fe (III)/MDPC-600 catalyst.

The MOF-5-based microporous carbon catalyst is used for phenol hydroxylation reaction.

Further improvement, the using method is as follows:

weighing Fe (III)/MDPC-600 catalyst, phenol, 30% hydrogen peroxide and deionized water, mixing in a round-bottom flask, reacting for 1-4h under the condition of magnetic stirring at the temperature of 70-90 ℃, filtering after the reaction is finished, extracting the filtrate for three times by using an extraction solvent, and analyzing the content of phenol and benzenediol in the extract by using a gas chromatograph-mass spectrometer; the mass ratio of the Fe (III)/MDPC-600 catalyst to the phenol is 1:10-1: 50; the volume ratio of the phenol to the hydrogen peroxide is 1:1-1: 20; the volume ratio of the phenol to the deionized water is 1:20-1: 60.

In a further refinement, the extraction solvent is at least one of ethyl acetate, chloroform, and carbon tetrachloride.

Drawings

FIG. 1 XRD spectra before and after acid pickling of MDPC-600;

FIG. 2 XRD spectrum of Fe (III)/MDPC-600;

FIG. 3 is an SEM image of sample A and MDPC-600;

FIG. 4 is an elemental distribution diagram of Fe (III)/MDPC-600 (2% Wt of Fe);

FIG. 5MDPC-600 has N2 adsorption/desorption isotherms and pore size distributions.

The specific implementation mode is as follows:

in order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below.