CN111437860A

CN111437860A - Catalyst, preparation method and application thereof

Info

Publication number: CN111437860A
Application number: CN202010224644.4A
Authority: CN
Inventors: 王郁现; 任诺; 席佳欣; 陈春茂
Original assignee: China University of Petroleum Beijing
Current assignee: China University of Petroleum Beijing
Priority date: 2020-03-26
Filing date: 2020-03-26
Publication date: 2020-07-24
Anticipated expiration: 2040-03-26
Also published as: CN111437860B

Abstract

The invention relates to a catalyst and a preparation method and application thereof, wherein the catalyst is a product obtained by roasting, carbonizing and annealing cobalt salt, an amine compound and cyclodextrin which are used as raw materials, and the product is provided with a carbon nano tube carrier, and active ingredients are loaded on the inner surface of the carrier. The catalyst provided by the invention is not easy to dissolve out metals in active components, avoids secondary pollution to the greatest extent, and can maintain good catalytic activity in a catalytic ozone system. In addition, the carrier of the catalyst is relatively firmer, so that the catalyst has better stability and reusability.

Description

Catalyst, preparation method and application thereof

Technical Field

The invention relates to the technical field of sewage treatment, in particular to a catalyst and a preparation method and application thereof.

Background

The important one of the environmental governance is the effective governance aiming at water pollution, industrial wastewater is one of the main pollution sources of water pollution, different from domestic wastewater, the discharged wastewater from various industries contains a plurality of organic matters which are difficult to degrade, such as polycyclic aromatic compounds, heterocyclic compounds and the like, and a targeted technical means is required to be introduced, so that the adverse effects of the organic matters on the living environment and the body health of people are reduced or avoided as much as possible.

For the organic matters which are difficult to degrade, the traditional treatment technology separates the organic matters from the sewage by changing the forms of the organic matters, and the organic matters are enriched and then are treated separately. The problem of such treatment is that firstly, the requirement on the separation means is high, and the cleanliness of the separated water body is still difficult to ensure; and effective degradation treatment is not carried out on organic matters in the wastewater. The currently accepted effective method is a catalytic ozone-oxidation technology, and an ozone oxidation system is characterized in that ozone is catalytically converted into singlet oxygen with stronger oxidation capacity under the action of a catalyst, so that the catalytic oxidation efficiency of ozone is improved, and the degradation of organic matters is accelerated.

At present, the catalysts for catalyzing the ozone decomposition are mainly divided into metal catalysts and non-metal catalysts, and have respective advantages and disadvantages in application. The efficiency of the metal catalyst is relatively high, but metal is easy to dissolve out in the process of catalyzing ozone oxidation, secondary pollution is caused, the service life of the catalyst is also reduced, and the treatment cost is increased. Although the non-metallic catalyst can avoid secondary pollution, the non-metallic catalyst is unstable in the process of degrading organic matters by ozone, is easily oxidized and decomposed by ozone and singlet oxygen, not only influences the catalytic efficiency, but also has the problem that the service life of the catalyst is reduced because the non-metallic catalyst cannot be reused.

Disclosure of Invention

Aiming at the defects of organic matter degradation treatment, the invention provides a catalyst which has good stability and reusability when being used in an ozone oxidation system, and can avoid secondary pollution while providing excellent catalytic efficiency.

The invention also provides a preparation method of the catalyst, and the catalyst meeting the requirements can be prepared through a simple and effective preparation process.

The invention also provides an application of the catalyst in the ozone oxidation degradation of organic matters and a method for realizing effective degradation of organic matters in sewage.

The invention firstly provides a catalyst, which is a product obtained by roasting, carbonizing and annealing cobalt salt, amine compounds and cyclodextrin serving as raw materials and has a carbon nano tube carrier, wherein active ingredients are loaded on the inner surface of the carrier.

In some embodiments, the active ingredient comprises cobalt and/or a cobalt nitride.

In some embodiments, the cobalt salt, the amine compound and the cyclodextrin are prepared from raw materials in a mass ratio of (0.5-2): 5: 1.

in some embodiments, the cyclodextrin is selected from α -cyclodextrin, β -cyclodextrin or gamma-cyclodextrin, the amine compound is selected from at least one of melamine, dicyandiamide, cyanamide and urea, and the cobalt salt is selected from an inorganic acid salt of cobalt.

In some embodiments, the catalyst is a product obtained by taking cobalt salt, an amine compound and cyclodextrin as raw materials and performing roasting carbonization treatment and annealing treatment, wherein the roasting carbonization treatment refers to drying a dispersion liquid formed by dispersing the cobalt salt, the amine compound and the cyclodextrin in a solvent and then roasting at the temperature of 500-600 ℃ to obtain a carbon material precursor; the annealing treatment refers to that the carbon material precursor is subjected to heat treatment at 600-1100 ℃ in a non-oxygen atmosphere and is cooled to obtain the catalyst.

In some embodiments, the calcination time is from 1 to 4 hours; the heat treatment time is 4-8 h.

The invention also provides a preparation method of the catalyst in any one of the embodiments, which comprises the following steps:

dispersing cobalt salt, amine compound and cyclodextrin in a solvent to form a dispersion liquid, and drying the dispersion liquid to obtain a solid;

roasting the solid at the temperature of 500-600 ℃ to obtain a carbon material precursor;

and carrying out heat treatment on the carbon material precursor at the temperature of 600-1100 ℃ in a non-oxygen atmosphere, and cooling to prepare the catalyst.

In some embodiments, the cyclodextrin is selected from α -cyclodextrin, the amine compound is selected from at least one of melamine, dicyandiamide, cyanamide and urea, and the cobalt salt is selected from cobalt nitrate, cobalt chloride or cobalt sulfate.

The invention also provides a method for degrading organic matters by using ozone oxidation, which comprises catalyzing the ozone oxidation system by using the catalyst in any one of the above embodiments.

The invention also provides a method for treating sewage containing organic matters by utilizing a catalytic ozonation method, and a catalytic ozonation system comprising the catalyst in the embodiment.

The embodiment of the invention has at least the following beneficial effects:

1) the catalyst provided by the invention is not easy to dissolve out metals in active components, avoids secondary pollution to the greatest extent, and can maintain good catalytic activity in a catalytic ozone system. In addition, the carrier of the catalyst is relatively firmer, so that the catalyst has better stability and reusability.

2) According to the preparation method of the catalyst, the cobalt salt, the amine compound and the cyclodextrin are used as raw materials, so that the raw materials are easy to obtain, and the preparation method is simple and convenient to operate.

3) The catalyst provided by the invention is applied to a system for degrading organic matters by ozone, and can improve the degradation efficiency of the organic matters by ozone.

Drawings

FIG. 1 is a Scanning Electron Microscope (SEM) image of a catalyst of example 1 of the present invention.

FIG. 2 is a Transmission Electron Microscope (TEM) image of the catalyst of example 1 of the present invention.

FIG. 3 is a Raman spectrum of the catalysts of examples 1, 3, 8 and 10 of the present invention.

FIG. 4 is a graph showing the degradation effect of the catalyst of example 1 of the present invention in an oxalic acid system degraded by ozone.

FIGS. 5(a) and (b) are X-ray diffraction photoelectron spectroscopy (XPS) charts of the catalyst of example 7 of the present invention.

Fig. 6 is an X-ray diffraction (XRD) pattern of the catalysts of examples 1, 8 and 10 of the present invention.

Fig. 7 is an XPS spectrum of the catalyst after three recycles of example 1, example 11 and example 1 of the present invention.

FIG. 8 is a graph showing the effect of the present invention in test examples 1 to 3 on oxalic acid degradation.

FIG. 9 is a graph showing the effect of degrading oxalic acid according to test examples 1, 4 and 5 of the present invention.

FIG. 10 is a graph showing the effect of degrading p-nitrophenol in test examples 6 to 8 of the present invention.

FIG. 11 is a graph showing the effect of the present invention in test examples 9 to 12 on oxalic acid degradation.

FIG. 12 is a graph showing the Total Organic Carbon (TOC) content in the catalytic ozone decomposition system in test example 13 of the present invention.

Detailed Description

The invention provides a catalyst, which is a product obtained by using cobalt salt, amine compounds and cyclodextrin as raw materials and through roasting, carbonizing and annealing treatment.

As described above, the catalyst according to the present invention uses carbon nanotubes as a carrier, and an active ingredient is supported on the inner surface of the carrier. By utilizing the catalyst with the shape and the composition to catalyze the ozone oxidation system, in the reaction process, active sites in active ingredients are not directly exposed to ozone, singlet oxygen and an acid environment, so that metals in the active ingredients are not easy to dissolve out, secondary pollution caused by the dissolution is avoided, and the catalyst can maintain good catalytic activity in the catalytic ozone system. On the other hand, the carbon nano tube carrier obtained by the mutual synergistic action of the cobalt salt, the amine compound and the cyclodextrin has limited structural defects, boundaries and a firm structure, is favorable for preventing the carrier from being damaged by ozone and singlet oxygen in the reaction process, and improves the stability and reusability of the catalyst in an ozone degradation organic system.

The active component of the catalyst is from cobalt and reaction products thereof, and active sites in the active component are also formed in the process of forming the carbon nano tube, wherein the active sites are cobalt-carbon/nitrogen bonds, and the electron transfer is promoted through the active sites, so that the catalytic efficiency of the catalyst is further improved. The cobalt can enable the catalyst to have certain magnetism, the industrial recovery rate of the catalyst can be greatly improved through an external magnetic field, and the problem that the catalyst is difficult to recover in the industry is solved.

In some embodiments of the invention, the mass ratio of the cobalt salt, the amine compound and the cyclodextrin is (0.5-2): 5:1, as 1:5: 1. 0.5: 5:1 and 2: 5: 1.

in some embodiments of the present invention, the cyclodextrin is selected from α -cyclodextrin, β -cyclodextrin and γ -cyclodextrin, and multiple types of cyclodextrin can be used alone or in combination to provide a carbon nanotube carrier to the catalyst, while the carrier is not easily decomposed by ozone and singlet oxygen, and to help to ensure better stability of the catalyst.

The catalyst of the invention takes cobalt salt, amine compound and cyclodextrin as raw materials, and is carbonized by utilizing the property of the cyclodextrin after proper heat treatment, such as roasting and annealing treatment, and finally becomes a carrier of a carbon nano tube structure, and cobalt and nitrogen in the cobalt salt and the amine compound are formed in the tube of the carrier in a form and structure with higher energy in the process and become components for providing catalytic activity. Depending on the choice of raw materials, suitable processing conditions, such as calcination treatment and annealing treatment, can be selected to give the desired carbon nanotube support and catalyst product. The term "annealing" as used herein in the present invention is understood to mean a heat treatment known as a heat treatment through a heating-holding-natural cooling process, such as a heat annealing in the field of polymer technology.

In the specific embodiment of the invention, the roasting treatment may refer to drying a dispersion liquid formed by dispersing cobalt salt, an amine compound and cyclodextrin in a solvent, and then roasting at 500-600 ℃ for 1-4h to obtain a carbon material precursor; the annealing treatment may be to perform heat treatment on the carbon material precursor at 600-1100 ℃ for 4-8h in a non-oxygen atmosphere, and to obtain the catalyst after cooling.

The invention also provides a preparation method of the catalyst, which comprises the following steps:

dispersing cobalt salt, amine compounds and cyclodextrin in water by ultrasonic and stirring to form uniform dispersion liquid, and drying the dispersion liquid to obtain a solid;

The purpose of preparing the dispersion liquid is to ensure that the cobalt salt can be well dispersed with the amine compound and the cyclodextrin, thereby being beneficial to the subsequent carbonization treatment. In some embodiments of the present invention, water may be used as a dispersing solvent to obtain a dispersion of the cobalt salt, the amine compound and the cyclodextrin. In order to disperse the cobalt salt, the amine compound and the cyclodextrin uniformly in water, conventional technical means well known to those skilled in the art, such as ultrasonic and stirring treatment, may be employed. In the specific implementation process of the invention, ultrasonic treatment and stirring treatment are carried out simultaneously, wherein the ultrasonic time is about 30min, the stirring speed is about 300r/min, and the stirring time is maintained for 2-3 h. The process maintains proper heating and is also beneficial to the dissolution and dispersion of the cyclodextrin.

The drying treatment of the dispersion may be carried out by conventional techniques well known to those skilled in the art, such as natural drying and vacuum drying. In a specific embodiment, the drying treatment of the dispersion is high-efficiency and quick through microwave drying, and the moisture in the dispersion can be sufficiently removed within 5min, and the specific drying process is as follows: treating the dispersion in a microwave dryer for 1min, shaking the dispersion, and repeating for 4-5 times to obtain solid with water removed.

And roasting the solid at the temperature of 500-600 ℃ to obtain the carbon material precursor, wherein the roasting time is 1-4 h.

The metallic cobalt element derived from the cobalt salt can promote graphitization of the carbon material precursor during the annealing treatment under the inert atmosphere, and as the treatment progresses, the metallic cobalt element is wrapped in the carbon nanotube in a certain form and adheres to the inner surface of the carbon nanotube in the form of a cobalt-carbon/nitrogen bond or the like to become an active site of the catalyst. In embodiments of the invention, the annealing process is typically carried out using a tube furnace operation, with the air being removed from the furnace, followed by a controlled non-oxygen environment for high temperature processing and cooling to produce the catalyst product. For example, the specific steps are as follows: firstly, heating a tubular furnace in which the precursor is placed to 30-50 ℃ at a speed of about 5 ℃/min, and then preserving heat for at least 0.5h to exhaust air in the tubular furnace; then introducing inert gas (such as nitrogen or argon) to enable the carbon material precursor to be in a non-oxygen atmosphere; raising the temperature in the tubular furnace to 600-1100 ℃ at the speed of about 5 ℃/min, then preserving the temperature for 4-8h, and cooling to obtain the catalyst. The catalyst has excellent catalytic activity, and can ensure that ozone has higher degradation efficiency in degrading organic matters.

As mentioned above, in the preparation process of the catalyst, the cobalt salt not only can make the catalyst have a carrier with a tubular structure, but also can form an active component of the catalyst, thereby improving the catalytic efficiency of the catalyst.

Further, in some embodiments of the present invention, the above cobalt salt specifically includes at least one of cobalt nitrate, cobalt chloride and cobalt sulfate, for example, cobalt nitrate, cobalt chloride, cobalt sulfate, a mixture of cobalt nitrate and cobalt chloride, a mixture of cobalt nitrate and cobalt sulfate, and a mixture of three of cobalt nitrate, cobalt chloride and cobalt sulfate. In a particular embodiment, the cobalt salt is selected from cobalt nitrate.

In some embodiments of the invention, the cyclodextrin is selected from the group consisting of α -cyclodextrin, β -cyclodextrin, and γ -cyclodextrin, and the three types of cyclodextrins can be used alone or in combination, and the resulting catalyst forms a carbon nanotube support with better stability.

The inventors have experimentally found that α -cyclodextrin can provide a carbon nanotube support with a relatively small pore size (e.g., referring to the results shown in fig. 1, most tubular supports have a pore size of less than 20nm, and tests by the applicant have also shown that a pore size of 5-14nm can be at least partially achieved), which is more advantageous for tightly packing the active ingredient in the inner wall thereof, and is less likely to allow the metal in the active ingredient to dissolve out, and can also provide a cobalt-nitrogen bond between the packed cobalt atom and the nitrogen atom to serve as a main active site in the active ingredient to improve the catalytic efficiency of the catalyst.

In some embodiments of the present invention, the amine-based compound may be selected from one or more of melamine, dicyandiamide, cyanamide and urea, such as a mixture of melamine and dicyandiamide, a mixture of melamine and cyanamide, a mixture of melamine and urea, and a mixture of melamine, dicyandiamide and cyanamide. In a particular embodiment, the amine based compound is selected from melamine.

According to the preparation method, the cobalt salt, the amine compound and the cyclodextrin are used as raw materials, the raw materials are easy to obtain, and the preparation method is simple and convenient to operate.

The invention also provides a method for degrading organic matters by ozone oxidation, which comprises the step of catalyzing the ozone oxidation system by using the catalyst of any embodiment, so that the degradation effect of the ozone system on the organic matters is effectively improved.

Based on the research, the invention also provides a method for treating the sewage containing the organic matters, which utilizes a catalytic ozonation method and uses a catalytic ozonation system comprising the catalyst. Thereby providing a new means for treating sewage containing various organic matters.

In order to test and prove the catalytic effect of the catalyst, oxalic acid and p-nitrophenol are respectively selected as degradation objects to carry out catalytic ozone oxidation experiments, and the results show that the catalyst can catalyze ozone to completely degrade oxalic acid within 15min and can catalyze ozone to completely degrade p-nitrophenol within 30 min. It is believed that the use of the catalyst of the present invention to catalyze ozone oxidation for organic degradation treatment (nitrophenol is the major contaminant in most cases) of, for example, petrochemical and pharmaceutical wastewater, provides excellent degradation effects.

In addition, the applicant studied the route of ozone degradation of organic matter through the above application. Compared with the current accepted research conclusion, the path of ozone degradation of organic matters is basically a free radical degradation path, namely ozone is oxidized and decomposed into singlet oxygen, and the singlet oxygen is used for oxidizing and decomposing the organic matters in the sewage into carbon dioxide and water. The catalyst is applied to a system for degrading organic matters by ozone, and degradation experiments and experiments of quenching free radicals show that the organic matters can be further degraded after singlet oxygen in the system is quenched, so that a non-free radical degradation path exists in addition to the free radical degradation path. The applicant believes that the research on the degradation path can be further enhanced, and can provide referential value for the degradation mechanism of the ozone on the organic matters in the sewage.

In order to make the objects, 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 drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

The preparation method of the catalyst comprises the following steps:

(1) dispersing 1g of cobalt nitrate, 5g of melamine and 1g of α -cyclodextrin in 100m L of water by ultrasonic wave for 30min, maintaining stirring by a magnetic stirrer to obtain a uniform dispersion liquid, setting the rotation speed of the stirrer to be 300r/min, maintaining stirring for 2-3h, continuously heating to about 80 ℃, and then evaporating the dispersion liquid by a microwave method to obtain a solid, wherein the specific process of evaporating by the microwave method comprises the steps of treating the dispersion liquid in a microwave dryer for about 1min, shaking the dispersion liquid, continuously treating, and repeating for 5 times.

(2) Grinding the solid, pouring the ground solid into a crucible, and roasting the solid in a muffle furnace to obtain an intermediate product, namely a carbon material precursor, wherein the roasting procedure is as follows: the temperature was raised to 550 ℃ at a rate of about 5 ℃/min and maintained at 550 ℃ for about 3 hours.

(3) Placing the quartz boat containing the carbon material precursors in a tube furnace to carry out annealing treatment, heating to 40 ℃ at the speed of 5 ℃/min, and keeping the temperature for 1h to exhaust air; and then introducing argon, maintaining the non-oxygen atmosphere, continuously heating at 5 ℃/min to 1100 ℃, roasting and keeping for 6 hours, naturally cooling to obtain the catalyst, wherein the name is 1:5:1-1100, Ar.

Fig. 1 is an SEM image of the catalyst of this example, and it can be seen from fig. 1 that the catalyst has a tubular structure, and based on fig. 1, it can be seen by visual inspection that the pore diameter of the catalyst of the tubular structure is less than 20 nm.

Fig. 2 is a TEM image of the catalyst of this example, and it can be seen from fig. 2 that the carrier contains the (111) crystal plane of Co, and therefore the carrier of the catalyst contains cobalt as an active component.

In the Raman spectrum curve of FIG. 3, the curve indicated by Ar is a Raman spectrum curve of the catalyst of this example at 1:5:1-1100, and as can be seen from FIG. 3, has a length of 1336cm^-1And 1581cm^-1And (3) nearby free vibration respiration peaks which are characteristic peaks of the carbon nano tube.

As can be confirmed by referring to fig. 1 to 3, the catalyst prepared in example 1 is a product of the structure of carbon nanotubes, and cobalt is attached as an active component to the inner wall surface.

The same characterization methods are used for the catalysts prepared in the subsequent examples, and the same results can be obtained, namely, the prepared catalysts are products with carbon nanotube structures, and cobalt is used as an active ingredient and is attached to the inner wall surface of the tubular structure.

The catalyst prepared in this example was subjected to a recycling experiment to detect the degradation efficiency of oxalic acid, and the degradation efficiencies detected at different times were plotted as curves, respectively, to form fig. 4.

The specific steps of the catalyst recycling experiment comprise:

1) 500m L was taken at a concentration of 50ppm (initial concentration C)₀) Putting oxalic acid as a detection sample in a reactor, adding 0.05g of catalyst, and performing ultrasonic treatment for 1 min;

2) putting the reactor into a water bath kettle, heating while starting magnetic stirring, wherein the rotating speed of magnetons is 200-;

3) introducing inert gas containing ozone into the reactor, wherein the ozone content is 25g/m³Controlling the flow rate to be 100m L/min, sampling after reacting for a period of time, wherein the sample is a solution after degradation reaction, and determining the concentration C of oxalic acid in the solution by a liquid chromatograph, which is equal to the initial concentration C of the sample₀Ratio of (C/C)₀) Which reflects the effect of the degradation of oxalic acid, i.e., the decrease of the ratio with the reaction time, can also be used to evaluate the degradation efficiency, e.g., the degradation efficiency approaches 100% when the ratio approaches 0, so that the applicant plotted the change curve in FIG. 4 according to which (C/C) is₀) As an index of degradation efficiency;

4) the catalyst was recovered for the next experiment and the results obtained are plotted in figure 4 by developing a degradation efficiency curve.

In FIG. 4, "Fresh" represents the degradation efficiency curves, "2 nd", "3 rd", "4 nd", of the first use of Fresh catalyst^th"represents degradation efficiency curves of the catalyst used repeatedly two to four times, respectively; "Regeneration" represents the degradation efficiency curve of the catalyst used after Regeneration.

As shown in fig. 4, in addition to the fresh catalyst, more than 90% of the oxalic acid was degraded in 20min during the second and third recycling of the catalyst, and the remaining oxalic acid was completely degraded as the reaction time increased. For the fourth recycle, 80% of the oxalic acid was degraded after 20min, and the remaining oxalic acid was completely degraded as the reaction time increased. It can be seen that the catalyst of the present embodiment has good catalytic efficiency and reusability, and the catalyst still has good catalytic performance after regeneration.

Examples 2 to 6

Examples 2-6 were prepared in substantially the same manner as in example 1, except for the firing temperature of the annealing treatment.

The temperature of the annealing calcination in example 2 was 1000 ℃, and the catalyst prepared was named 1:5: 1-1000, Ar.

The temperature of the annealing calcination in example 3 was 900 ℃, and the catalyst prepared was named 1:5: 1-900, Ar, reference example 1, the raman spectrum of the catalyst is 1:5: 1-900, Ar, with a characteristic peak of carbon nanotubes in the curve.

The temperature of the annealing calcination in example 4 was 800 ℃, and the catalyst prepared was named 1:5: 1-800, Ar.

The temperature of the annealing calcination in example 5 was 700 ℃, and the catalyst prepared was named 1:5: 1-700, Ar.

The temperature of the annealing calcination in example 6 was 600 ℃, and the catalyst prepared was named 1:5: 1-600, Ar.

Example 7

The preparation method of this example is substantially the same as that of example 1, except that: the mass of the cobalt nitrate is 0.5g, the annealing and roasting temperature is 900 ℃, and the prepared catalyst is named as 0.5: 5: 1-900 and Ar.

Fig. 5(a) and 5(b) are XPS charts of the catalyst of the present example, from which it can be determined that the elements cobalt and nitrogen exist in different valence states and morphologies in the catalyst and the respective contents thereof, which the inventors have listed in table 1 for the sake of more clarity. It was confirmed that the catalyst carrier contained cobalt and nitrogen in different forms, and that nitrogen atoms and cobalt atoms were capable of forming Co-N_xThe activity of the catalyst should be derived from the metallic cobalt and the cobalt nitrogen bond in the cobalt nitrogen compound.

TABLE 1

Co⁰(at％)	14.7
		Co 2p(at％)	30.6
Co-N_x(at％)	16.8
		Co 2p 3/2satellite(at％)	9.3
Co ⁰ 2p 1/2(at％)	8.3
		Co 2p 1/2(at％)	11.8
Co 2p 1/2satellite(at％)	8.6
		Pyridine nitrogen/Co-N_x(at％)	21.3
Pyrrole nitrogen (at%)	29.3
		Graphite Nitrogen (at%)	37.4
Nitrogen oxide (at%)	12.0

Example 8

The preparation method of this example is substantially the same as that of example 7, except that: the temperature of annealing and roasting is 1100 ℃, and the prepared catalyst is named as 0.5: 5:1-1100, Ar. The raman spectrum produced by the same method is shown as 0.5 in fig. 3: 5:1-1100, Ar, with a characteristic peak of carbon nanotubes in the curve.

Example 9

The preparation method of this example is substantially the same as that of example 1, except that: the mass of the cobalt nitrate is 2g, the annealing and roasting temperature is 900 ℃, and the prepared catalyst is named as 2: 5: 1-900 and Ar.

Example 10

The preparation method of this example is substantially the same as that of example 9, except that: the temperature of annealing and roasting is 1100 ℃, and the prepared catalyst is named as 2: 5:1-1100, Ar. The raman spectrum made by the same method is 2 in fig. 3: 5:1-1100, Ar, with a characteristic peak of carbon nanotubes in the curve.

Test examples 1 to 3: effect of cobalt salt content on catalytic Activity

The test method is as follows:

3) introducing inert gas containing ozone into the reactor, wherein the ozone content is 25g/m³Controlling the flow rate to be 100m L/min, sampling after reacting for a period of time, determining the concentration C of oxalic acid in the solution by a liquid chromatograph, and the initial concentration C of the oxalic acid and the initial concentration C of the sample₀Ratio of (C/C)₀) Can reflect the degradation effect on oxalic acid.

In test example 1, the catalyst 1 of example 1 was used: 5:1-1100, Ar, the resulting degradation efficiency curves over different times are 1 in fig. 8: 5:1-1100, curve indicated by Ar.

In test example 2, the catalyst of example 8 was used in a ratio of 0.5: 5:1-1100, Ar, the resulting degradation efficiency curves over time are 0.5 in fig. 8: 5:1-1100, curve indicated by Ar.

In test example 3, catalyst 2 of example 10 was used: 5: 1-900, Ar, the resulting degradation efficiency curves over different times are 2 in fig. 8: 5: 1-900, curve indicated by Ar.

The degradation efficiency at different times was determined by test examples 1, 2 and 3, as shown in fig. 8. It can be seen that the catalysts prepared in examples 1, 8 and 10 all have better catalytic efficiency.

Test examples 4 to 5: modification of the Oxidation System

See test examples 1-3 for the following differences:

test example 4 ozone was not introduced.

Test example 5 no catalyst was added.

Test examples 1, 4 and 5, in which the effect of degradation of oxalic acid was tested by different methods, are shown in FIG. 9, respectively, and the curves of the degradation efficiency with time are shown in FIG. 4, in which test example 4 passed only the adsorption of the catalyst (labeled as 1:5:1-1100 in the figure, Ar adsorption), and in which test example 5 passed only the oxidation of ozone without using the catalyst (labeled as O in the figure)₃Alone), test example 1 catalyzes the action of ozone oxidation by a catalyst (identified as 1:5:1-1100, Ar in the figure). It can be clearly shown that the catalyst catalyzes the ozone oxidation to realize the degradation of the oxalic acid.

Test examples 6 to 8: p-nitrophenol degradation test

See test examples 1-3, but the degraded organics changed oxalic acid to p-nitrophenol and:

test example 6 using catalyst 1:5:1-1100, Ar, and introducing ozone.

In test example 7, ozone was not introduced.

No catalyst was added in test example 8.

With reference to the foregoing experimental examples 1,4 and 5, the degradation efficiency curves of test examples 6, 7 and 8 with respect to time are shown in FIG. 10, and it can be seen that for the degradation of p-nitrophenol, ozone oxidation (in the figure, "O" is used) is directly used, depending on the fact that the catalyst is ineffective (in the figure, "adsorption" curve), and₃alone) has shown some effect, there is a clear advantage over catalytic ozonation ("1: 5:1100, Ar catalyzed ozonation" as shown in the figure).

Test examples 9 to 12: quencher assay

The test method is shown in test examples 1-3, except that different quenchers are added in step 1), specifically, oxalic acid with the concentration of 50ppm and 500m L is taken as a detection sample, the detection sample is placed in a reactor, the quenchers are added to obtain a mixed solution, the pH of the mixed solution is adjusted to 3, then 0.05g of catalyst is added, and the results of ultrasonic treatment for 1min and degradation efficiency are shown in FIG. 11.

In test example 9, 4mM methanol was added as a quenching agent, and the methanol quenches the hydroxyl radical in the solution (1:5:1-1100, Ar +4mM methanol).

In Experimental example 10, 4mM furfuryl alcohol (FFA) quencher was added, which quenches singlet oxygen from the solution and from the catalyst (1:5:1-1100, Ar +4mM FFA).

In test example 11, 2mM NaN was added₃A quenching agent capable of quenching singlet oxygen (1:5:1-1100, Ar +2mM NaN) in solution and in the catalyst₃)。

Test example 12 is a control test, i.e., the procedure was the same as in test example 1 without adding any quencher (1:5:1-1100, Ar).

In the test example 9, methanol for quenching hydroxyl radicals is added, and compared with the control test of the test example 12, the result shows that the catalytic ozonation system contains hydroxyl radicals, and the hydroxyl radicals can improve the degradation efficiency of oxalic acid; in test examples 10 and 11, quenchers for quenching singlet oxygen were added, respectively, and compared with the degradation efficiency obtained in test example 12, it can be shown that when singlet oxygen (i.e., free radicals) is quenched by the quenchers, oxalic acid can still be degraded, but the degradation efficiency is low. From the above, it is considered that the catalyst provided by the present invention is applied to a system in which ozone degrades an organic substance, and a non-radical degradation pathway is present in addition to a radical degradation pathway.

Test example 13: total Organic Carbon (TOC) content test

See test examples 1-3 for test methods with the following differences: substitution of oxalic acid with ultrapure water and the reaction of catalyst 1 prepared in example 1:5:1-1100, putting the solution obtained after the catalytic reaction of Ar and ozone into a TOC measuring instrument to measure the TOC content in the solution.

FIG. 12 is a graph showing the TOC content of the measured solution as a function of the ozone contact time, from which it can be seen that the catalyst 1 prepared in example 1:5:1-1100, the TOC increment in the solution obtained after the catalytic reaction of Ar and ozone is not obvious, thereby further showing that the carrier of the catalyst stably exists in the solution after the catalytic reaction, and basically no carbon is released, namely the carrier is not easily damaged by ozone or singlet oxygen.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. The catalyst is characterized in that the catalyst is a product obtained by using cobalt salt, amine compounds and cyclodextrin as raw materials and through roasting, carbonizing and annealing treatment, and the product is provided with a carbon nano tube carrier, wherein an active component is loaded on the inner surface of the carrier.

2. The catalyst according to claim 1, wherein the active component contains cobalt and/or a cobalt nitride.

3. The catalyst according to claim 1 or 2, characterized in that the cobalt salt, the amine compound and the cyclodextrin are prepared from raw materials in a mass ratio of (0.5-2): 5: 1.

4. the catalyst of claim 3, wherein the cyclodextrin is selected from α -cyclodextrin, β -cyclodextrin or gamma-cyclodextrin, the amine compound is at least one selected from melamine, dicyandiamide, cyanamide and urea, and the cobalt salt is selected from inorganic acid salts of cobalt.

5. The catalyst according to any one of claims 1 to 4, wherein the catalyst is a product obtained by performing calcination carbonization treatment and annealing treatment on a cobalt salt, an amine compound and cyclodextrin as raw materials, wherein the calcination carbonization treatment is to dry a dispersion liquid formed by dispersing the cobalt salt, the amine compound and the cyclodextrin in a solvent and then perform calcination at 600 ℃ to obtain a carbon material precursor; the annealing treatment refers to that the carbon material precursor is subjected to heat treatment at 600-1100 ℃ in a non-oxygen atmosphere and is cooled to obtain the catalyst.

6. The catalyst of claim 5, wherein the calcination time is 1-4 hours; the heat treatment time is 4-8 h.

7. A process for preparing a catalyst as claimed in any one of claims 1 to 6, characterized by comprising the steps of:

8. The preparation method according to claim 7, wherein the cyclodextrin is α -cyclodextrin, the amine compound is at least one selected from melamine, dicyandiamide, cyanamide and urea, and the cobalt salt is cobalt nitrate, cobalt chloride or cobalt sulfate.

9. A method for degrading organic substances by ozone oxidation, comprising catalyzing the ozone oxidation system with the catalyst according to any one of claims 1 to 6.

10. A method for treating organic matter-containing waste water, characterized by using a catalytic ozonation method using a catalytic ozonation system comprising the catalyst according to any one of claims 1 to 6.