CN111054417A

CN111054417A - High-efficiency iron monatomic Fenton catalyst, and synthesis method and application thereof

Info

Publication number: CN111054417A
Application number: CN201911304515.XA
Authority: CN
Inventors: 李燕; 张惠智; 王永彬; 王硕; 张爱群; 辛卫东; 卞峰; 牛蔚然; 王瑞琪; 朱国梁; 魏姗姗; 杨伟进; 李一真; 魏嘉萍
Original assignee: Jinan Huizhi Power Technology Co ltd; State Grid Shandong Integrated Energy Service Co ltd
Current assignee: Jinan Huizhi Power Technology Co ltd; State Grid Shandong Integrated Energy Service Co ltd
Priority date: 2019-12-17
Filing date: 2019-12-17
Publication date: 2020-04-24
Anticipated expiration: 2039-12-17
Also published as: CN111054417B

Abstract

The invention relates to a high-efficiency iron monatomic Fenton catalyst, a synthetic method and application thereof. In the catalyst, the iron active substance is anchored on the nitrogen-doped carbon carrier in a single atom form, and the load is 0.3-10 wt%. The preparation method is a prepolymerization-roasting process. The catalyst has the advantages of good dispersibility in water, high catalytic activity, wide pH response and the like. The preparation process has the advantages of wide raw material source, simple and convenient operation, low requirement on equipment and easy realization of industrial production.

Description

High-efficiency iron monatomic Fenton catalyst, and synthesis method and application thereof

Technical Field

The invention belongs to the technical field of preparation of environment-friendly functional materials and catalytic materials, and particularly relates to a high-efficiency iron monatomic Fenton catalyst, a preparation method thereof and application thereof in organic wastewater treatment.

Background

The information in this background section is only for enhancement of understanding of the general background of the invention and is not necessarily to be construed as an admission or any form of suggestion that this information forms the prior art that is already known to a person of ordinary skill in the art.

High-concentration organic wastewater generated by a power generation plant is a technical problem of sewage treatment technology, and the operation and production of equipment of power generation enterprises are seriously influenced by organic pollution of water quality. For example, the heat exchange equipment is one of the common equipments in the process production, the water quality entering the heat exchange equipment is poor, after a period of operation, the organic pollution and the inorganic ions can generate some solid attachments on the heated surface contacted with water to scale, the temperature of the metal pipe wall of the scaling part is too high, the metal strength is reduced, and thus, under the action of the pressure in the pipe, serious accidents such as pipe explosion and the like can occur. The scaling not only harms the safe operation of the heat exchange equipment of the power plant, but also greatly reduces the economical efficiency of industrial production. And water quality pollution can cause corrosion of equipment. If the water quality is poor, metal parts of operating equipment are easy to corrode, the corrosion shortens the service life of the equipment per se and causes economic loss, metal corrosion products fall into water, impurities in the water increase, then scaling on the heating surface with high heat load is aggravated, new scaling continues to accelerate corrosion, and the vicious circle can rapidly cause a pipe explosion event. Organic pollution easily causes the increase of membrane filtration pressure in an ultrafiltration reverse osmosis system, reduces the service life of a membrane and increases the energy consumption of the system, so that the efficient removal of organic pollutants becomes an important subject in zero discharge of power plant wastewater, and the method is an important means for treating high-concentration organic wastewater and an important pretreatment process of ultrafiltration reverse osmosis process water.

The Fenton-like catalytic method based on oxidants such as hydrogen peroxide, ozone and the like is the most important chemical treatment means for treating organic sewage at present. The Fenton reaction mainly utilizes hydrogen peroxide and ozone to generate superoxide radical and hydroxyl radical with high reaction activity under the catalytic action of a catalyst, and the organic matters are mineralized and converted into carbon dioxide and water through the strong oxidizing property of the radical, so that the organic matters which are difficult to degrade and cannot be removed by the traditional water treatment technology are effectively removed. However, the traditional fenton catalytic method has poor catalyst activity, catalytic reaction needs to be carried out under lower pH, and the utilization rate of the oxidant is lower, so that the process operation cost is greatly improved, and secondary pollution such as red mud byproducts is also generated.

Compared with the traditional iron ion Fenton catalyst and solid oxide catalyst, the monatomic Fenton catalyst is a new Fenton catalyst, and has the advantages of extremely high catalytic activity, wide pH working range, no by-product and the like. Since the monoatomic catalyst is proposed in 2011, the monoatomic catalyst is widely researched, but the preparation process is relatively complex all the time, and the product yield is low. The patent with the application number of CN201910758076.3 discloses a method for preparing a nickel monatomic catalyst by light deposition, but the single-batch preparation amount is only dozens of milligrams, and the large-scale production is difficult; patent publication No. CN107096536B reports a method for preparing transition metal monoatomic by oxidizing carbon carriers with mixed acid and then reducing and depositing with a reducing agent, but the preparation process flow is longer and the catalyst yield is low; patent with application number CN201910359944.0 reports a method for preparing a transition metal monatomic catalyst by using metallocene and mesoporous carbon as precursors through high-temperature roasting, acid washing and drying, but the cost of raw materials is high, and the method is not suitable for actual production; the activity of a monatomic iron catalyst in Fenton catalytic reaction is reported for the first time by a professor group in the stretch of Dalmatite (J.Am.chem.Soc.2018,140,39,12469 and 12475), but the preparation method is complex, the loading capacity of the prepared catalyst is low, and a large amount of pickling waste liquid is generated.

Disclosure of Invention

The invention aims to overcome the defects of complex preparation process and low load capacity of the existing monatomic, adopts a method with simple process flow, simple and convenient operation and low cost, and directly bakes the iron-doped organic acid-base gel as a precursor to form the high-efficiency iron monatomic Fenton catalyst with good catalytic performance and high load capacity.

In order to achieve the technical purpose, the technical scheme adopted by the invention is as follows:

a high efficiency iron monatomic fenton catalyst comprising:

a nitrogen-doped carbon support;

iron element loaded on the nitrogen-doped carbon carrier;

the iron element is present in a monoatomic form.

Aiming at the defects of the current preparation method of the iron monatomic catalyst, the simple high-load iron monatomic catalyst is developed, so that the performance of the Fenton catalytic reaction can be exerted to the greatest extent, the defects of long process flow and high cost are overcome, the catalytic performance is further improved, and a larger industrial application value is obtained.

In some embodiments, the iron loading in the catalyst is from 0.3 to 10 wt%. The load of the single-atom iron of the high-efficiency iron single-atom Fenton catalyst is higher than that of the traditional single-atom catalyst, and the high-efficiency iron single-atom Fenton catalyst has higher catalytic activity.

In some embodiments, the nitrogen doping amount of the nitrogen-doped carbon carrier is 5-50 wt%, and the size of the carrier is 0.05-20 μm, so that the catalytic performance and activity of the catalyst are improved.

The invention also provides a preparation method of the high-efficiency iron monatomic Fenton catalyst, which comprises the following steps:

dissolving organic acid and organic alkali in water, and mixing uniformly to form gel liquid;

putting an iron source into the gel liquid, heating and refluxing to fully mix the iron source into the gel component, carrying out solid-liquid separation on the refluxed suspension to obtain a pre-polymerized solid product, and freeze-drying to obtain gel powder;

and roasting the gel powder to obtain the high-efficiency iron monatomic Fenton catalyst.

The gel system can effectively disperse and stabilize iron ions, so that a high-load monoatomic state can be maintained in the roasting process.

The specific source of the organic acid is not particularly limited, and in some embodiments, the organic acid is a mono-basic, di-basic, or tri-basic organic acid with a molecular weight of 20 to 500, including but not limited to any one or more of formic acid, acetic acid, oxalic acid, propionic acid, malonic acid, acrylic acid, butyric acid, crotonic acid, butenedioic acid, adipic acid, benzoic acid, and oleic acid;

the specific source of the organic base is not particularly limited, and in some embodiments, the organic base is a mono-basic, di-basic, or tri-basic organic base with a molecular weight of 30 to 800, including but not limited to any one or more of urea, ethylenediamine, benzylamine, propylamine, phenylenediamine, hexamethylenediamine, oleylamine, melamine, dicyandiamide, and trimethylhexadecylammonium bromide.

The specific source of the iron source is not particularly limited, and in some embodiments, the iron source is one or more of ferric sulfate, ferrous sulfate, ferric nitrate, ferrous acetate, ferric acetate, ferrous chloride, ferric acetylacetonate and ferrous acetylacetonate, and by utilizing the characteristics that the active iron component has strong tolerance to acid and alkali and is not easy to dissolve out, the loss of the catalyst in practical application is effectively prevented, and the high efficiency and stability of the catalyst are realized.

In some embodiments, the molar ratio of the organic acid to the organic base is from 1:0.1 to 1: 10;

in some embodiments, the iron source is used in an amount of 0.1% to 50% of the total mass of the organic acid and the organic base.

In some embodiments, the reflux temperature is 60-110 ℃, and the reflux reaction time is 2-24 h;

in some embodiments, the roasting temperature is 400-1000 ℃, the roasting time is 0.5-6 h, and the roasting atmosphere is nitrogen, argon or a mixed gas atmosphere of the nitrogen and the argon.

The invention also provides a high-efficiency iron monatomic Fenton catalyst prepared by any one of the methods.

The invention also provides application of any one of the high-efficiency iron monatomic Fenton catalysts in sewage treatment.

The invention has the beneficial effects that:

(1) the load of the single-atom iron of the high-efficiency iron single-atom Fenton catalyst is higher than that of the traditional single-atom catalyst, and the high-efficiency iron single-atom Fenton catalyst has higher catalytic activity.

(2) The high-efficiency iron monatomic Fenton catalyst is prepared from cheap industrial raw materials, and is simple in preparation process, low in cost and easy to prepare in a large scale.

(3) According to the high-efficiency iron monatomic Fenton catalyst, the active iron component has strong tolerance to acid and alkali, is not easy to dissolve and separate out, effectively prevents the loss of the catalyst in practical application, and realizes high efficiency and stability of the catalyst.

(4) The high-efficiency iron monatomic Fenton catalyst has good catalytic activity on hydrogen peroxide and ozone serving as oxidants, greatly improves the utilization rate of the oxidants, and reduces the water treatment cost.

(5) The operation method is simple, low in cost, universal and easy for large-scale production.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the application and, together with the description, serve to explain the application and are not intended to limit the application.

FIG. 1: example 1 scanning electron micrographs of a high efficiency iron monatin catalyst;

FIG. 2: comparative example 1 scanning electron microscopy of nitrogen doped carbon.

Detailed Description

It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.

As introduced in the background art, the method aims at solving the problems that the existing preparation method of the iron monatomic catalyst is complex, the prepared catalyst has low loading capacity and generates a large amount of pickling waste liquid. Therefore, the invention provides a high-efficiency iron single-atom Fenton catalyst, which comprises an active iron element and a nitrogen-doped carbon carrier. The gel system can effectively disperse and stabilize iron ions, so that a high-load monoatomic state is maintained in the roasting process, and the preparation method is simple, low in cost and high in efficiency.

In a preferred embodiment of the first aspect of the present invention, the iron loading in the catalyst is 0.3 to 10 wt%, and the active iron element is loaded in a single atom form on the nitrogen-doped carbon support in which the nitrogen doping amount is 5 to 50 wt% and the support size is 0.05 to 20 μm, without forming nanoclusters or particles.

The second aspect of the present invention provides a prepolymerization-calcination synthesis method of the high efficiency iron monatomic fenton catalyst, comprising the following steps:

(1) dissolving organic acid and organic base in water, stirring and mixing to form gel liquid.

(2) And (2) putting iron salt into the gel liquid obtained in the step (1), heating and refluxing to fully mix an iron source into the gel component, carrying out solid-liquid separation on the refluxed suspension, and freeze-drying the obtained prepolymerization solid product to remove water to obtain gel powder.

(3) And (3) roasting the gel powder obtained in the step (2) in an inert atmosphere, and cooling to room temperature to obtain the high-efficiency iron monatomic Fenton catalyst.

Preferably, the organic acid is a mono-element, di-element or tri-element organic acid with the molecular weight of 20-500, and includes but is not limited to any one or more of formic acid, acetic acid, oxalic acid, propionic acid, malonic acid, acrylic acid, butyric acid, crotonic acid, butenedioic acid, adipic acid, benzoic acid, benzenedicarboxylic acid and oleic acid.

Preferably, the organic base is a monobasic, dibasic or tribasic organic base with the molecular weight of 30-800, and includes but is not limited to any one or more of urea, ethylenediamine, benzylamine, propylamine, phenylenediamine, hexamethylenediamine, oleylamine, melamine, dicyandiamide and trimethylhexadecylammonium bromide.

Preferably, the molar ratio of the organic acid to the organic base is 1:0.1 to 1: 10.

Preferably, the gel liquid has a solid content of 5g/L to 200 g/L.

Preferably, the iron source is one or more of ferric sulfate, ferrous sulfate, ferric nitrate, ferrous acetate, ferric acetate, ferrous chloride, ferric acetylacetonate and ferrous acetylacetonate.

Preferably, the total mass ratio of the iron source to the organic acid-base is 0.001: 1-0.500: 1.

Preferably, the reflux temperature is 60-110 ℃, and the reflux reaction time is 2-24 h.

Preferably, the roasting temperature is 400-1000 ℃, the roasting time is 0.5-6 h, and the roasting atmosphere is nitrogen, argon or a mixed gas atmosphere of the nitrogen and the argon.

The present invention is described in further detail below with reference to specific examples, which are intended to be illustrative of the invention and not limiting.

Example 1:

5.00g of dicyandiamide, 3.00g of butenedioic acid and 100mL of water were mixed and stirred uniformly to obtain a gel solution. 0.200g of ferric sulfate is weighed into the gel solution and stirred and refluxed for 12h at 90 ℃. After the reaction is finished, cooling the gel liquid to room temperature, centrifuging to obtain gel, and freeze-drying to obtain gel powder. Placing the powder in a square boat, heating at a rate of 10 ℃/min under the protection of nitrogen atmosphere in a tubular atmosphere furnace, and roasting at 700 ℃ for 2 h. And cooling to room temperature to obtain the high-efficiency iron monatomic Fenton catalyst. Fig. 1 is an SEM picture of the catalyst of example 1, and it can be seen that the catalyst is a carbon nanotube structure, which is more favorable for fully exposing active sites and improving catalytic degradation activity; the catalyst has no obvious iron compound particles, and the monoatomic dispersion state of the catalyst is proved.

Example 2:

a gel solution was obtained by mixing 4.00g of hexamethylenediamine, 2.00g of phthalic acid and 100mL of water and stirring them uniformly. 0.150g of ferric acetate is weighed into the gel solution and stirred and refluxed for 6h at 100 ℃. After the reaction is finished, cooling the gel liquid to room temperature, centrifuging to obtain gel, and freeze-drying to obtain gel powder. Placing the powder in a square boat, heating at a rate of 5 ℃/min under the protection of nitrogen atmosphere in a tubular atmosphere furnace, and roasting at 900 ℃ for 0.5 h. And cooling to room temperature to obtain the high-efficiency iron monatomic Fenton catalyst.

Example 3:

3.00g of p-phenylenediamine, 3.00g of succinic acid and 100mL of water are mixed and stirred uniformly to obtain gel liquid. 0.100g of ferric sulfate was weighed into the above gel solution, and stirred and refluxed at 75 ℃ for 12 hours. After the reaction is finished, cooling the gel liquid to room temperature, centrifuging to obtain gel, and freeze-drying to obtain gel powder. Placing the powder in a square boat, heating at a rate of 10 ℃/min under the protection of nitrogen atmosphere in a tubular atmosphere furnace, and roasting at 800 ℃ for 2 h. And cooling to room temperature to obtain the high-efficiency iron monatomic Fenton catalyst.

Example 4:

5.00g of aniline, 3.00g of oxalic acid and 100mL of water were mixed and stirred uniformly to obtain a gel solution. 0.200g of ferric nitrate was weighed into the above gel solution, and stirred and refluxed at 80 ℃ for 9 hours. After the reaction is finished, cooling the gel liquid to room temperature, centrifuging to obtain gel, and freeze-drying to obtain gel powder. Placing the powder in a square boat, heating at a rate of 10 ℃/min under the protection of nitrogen atmosphere in a tubular atmosphere furnace, and roasting at 700 ℃ for 6 h. And cooling to room temperature to obtain the high-efficiency iron monatomic Fenton catalyst.

Example 5:

10.00g of urea, 10.00g of oxalic acid and 100mL of water were mixed and stirred uniformly to obtain a gel solution. 0.170g of ferric sulfate was weighed into the gel solution and stirred under reflux at 60 ℃ for 12 h. After the reaction is finished, cooling the gel liquid to room temperature, centrifuging to obtain gel, and freeze-drying to obtain gel powder. Placing the powder in a square boat, heating at a rate of 10 ℃/min under the protection of nitrogen atmosphere in a tubular atmosphere furnace, and roasting at 750 ℃ for 2 h. And cooling to room temperature to obtain the high-efficiency iron monatomic Fenton catalyst.

Comparative example 1:

5.00g of dicyandiamide, 3.00g of butenedioic acid and 100mL of water are mixed, and the obtained gel solution is stirred uniformly and refluxed for 12 hours at 90 ℃. After the reaction is finished, cooling the gel liquid to room temperature, centrifuging to obtain gel, and freeze-drying to obtain gel powder. Placing the powder in a square boat, heating at a rate of 10 ℃/min under the protection of nitrogen atmosphere in a tubular atmosphere furnace, and roasting at 700 ℃ for 2 h. After cooling to room temperature, the nitrogen-doped carbon catalyst was obtained as shown in fig. 2.

As can be seen from table one, compared to comparative example 1, the high efficiency fe monatomic fenton catalysts in examples 1 to 5 have a high degradation rate for pollutants in simulated organic wastewater, can effectively degrade organic pollutants within 30 minutes of reaction time, and show high degradation activity under the conditions of hydrogen peroxide and ozone as oxidants, and have high efficiency and wide applicability.

TABLE-degradation rate of synthetic catalyst for 30 min of different simulated wastewaters

It should be noted that the above-mentioned embodiments are only preferred embodiments of the present invention, and the present invention is not limited thereto, and although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that modifications and equivalents can be made in the technical solutions described in the foregoing embodiments, or equivalents thereof. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention. Although the embodiments of the present invention have been described with reference to the accompanying drawings, it is not intended to limit the scope of the present invention, and it should be understood by those skilled in the art that various modifications and variations can be made without inventive efforts by those skilled in the art based on the technical solution of the present invention.

Claims

1. A high efficiency iron monatomic fenton catalyst, comprising:

a nitrogen-doped carbon support;

iron element loaded on the nitrogen-doped carbon carrier;

the iron element is present in a monoatomic form.

2. The high efficiency iron monatin catalyst according to claim 1, wherein the iron loading in said catalyst is 0.3 to 10 wt%.

3. The high efficiency Fe-monatomic Fenton catalyst according to claim 1, wherein the amount of nitrogen doped in the nitrogen-doped carbon carrier is 5 to 50 wt%, and the size of the carrier is 0.05 to 20 μm.

4. A preparation method of a high-efficiency iron monatomic Fenton catalyst is characterized by comprising the following steps:

5. The preparation method of the high efficiency Fe-monatomic Fenton catalyst according to claim 4, wherein the organic acid is a mono-organic acid, a di-organic acid or a tri-organic acid with a molecular weight of 20 to 500, and the organic acid includes but is not limited to any one or more of formic acid, acetic acid, oxalic acid, propionic acid, malonic acid, acrylic acid, butyric acid, crotonic acid, butenedioic acid, adipic acid, benzoic acid and oleic acid;

or the organic base is a monobasic, dibasic or tribasic organic base with the molecular weight of 30-800, and comprises any one or more of urea, ethylenediamine, benzylamine, propylamine, phenylenediamine, hexamethylenediamine, oleylamine, melamine, dicyandiamide and trimethyl hexadecyl ammonium bromide.

6. The method for preparing a high efficiency Fe-monatin catalyst according to claim 4, wherein the iron source is one or more selected from the group consisting of ferric sulfate, ferrous sulfate, ferric nitrate, ferrous acetate, ferric acetate, ferrous chloride, ferric acetylacetonate, and ferrous acetylacetonate.

7. The method for preparing a high efficiency Fe-monatin catalyst according to claim 4, wherein the molar ratio of the organic acid to the organic base is 1:0.1 to 1: 10;

or the dosage of the iron source is 0.1-50% of the total mass of the organic acid and the organic alkali.

8. The method for preparing the high-efficiency Fe-monatin catalyst according to claim 4, wherein the reflux temperature is 60-110 ℃, and the reflux reaction time is 2-24 h;

or the roasting temperature is 400-1000 ℃, the roasting time is 0.5-6 h, and the roasting atmosphere is nitrogen, argon or a mixed gas atmosphere of the nitrogen and the argon.

9. A high efficiency iron monatin catalyst produced by the method of any one of claims 4-8.

10. Use of the high efficiency iron monatin catalyst according to any one of claims 1 to 3 or 9 for sewage treatment.