CN-121534770-B - High-dispersion cobalt-based catalyst and preparation method and application thereof

Abstract

The invention discloses a high-dispersion cobalt-based catalyst and a preparation method and application thereof, belonging to the technical field of cobalt-based catalysts, wherein the invention takes tetracarboxyl cobalt phthalocyanine and nitrogen-defective carbon nanotubes as raw materials, forms a pre-assembled compound through molecular self-assembly in an organic solvent, then carries out programmed microwave heating on the pre-assembled compound to obtain the high-dispersion cobalt-based catalyst, the invention utilizes the means of combining specific molecular precursors with carrier defect engineering, constructs a 'molecular anchor-anchor positioning' pre-connection system through liquid phase pre-assembly, and is aided by the principle of accurate input of programmed microwave energy, thereby successfully solving the key technical problems of easy agglomeration of metal atoms, uncontrollable active site structure, mediocre catalytic performance and the like existing in the preparation of the cobalt-based catalyst by the existing microwave method.

Inventors

• WANG XUNLIANG
• XIE BAOLONG
• XIE DONGCHANG
• MA YUHUI
• CAO JUNRUI
• CHENG YU
• ZHAO JIN
• JIANG TIANXIANG
• ZHANG AIJUN

Assignees

• 自然资源部天津海水淡化与综合利用研究所

Dates

Publication Date

20260508

Application Date

20260115

Claims (7)

1. 1. The preparation method of the high-dispersion cobalt-based catalyst is characterized in that cobalt tetra-carboxyl phthalocyanine and nitrogen-deficient carbon nanotubes are used as raw materials, a pre-assembled compound is formed by molecular self-assembly in an organic solvent, and then the pre-assembled compound is subjected to programmed microwave heating to obtain the high-dispersion cobalt-based catalyst; the programmed microwave heating is divided into three stages of heating, the power of the second stage heating is larger than that of the first stage heating, and the power of the third stage heating is larger than that of the second stage heating; the specific steps of the programmed microwave heating are that the pre-assembled compound is put into a microwave reactor, inert gas is introduced to replace air, and three-stage heating is carried out: The first stage, heating for 5-8min with 300-400W power to raise the temperature to 250-300 deg.C; the second stage, switching to 500-600W power, heating for 10-15min, and maintaining the temperature at 350-400 ℃; A third stage of switching to 700-800W power, heating for 15-30s, raising the temperature to 600-700 ℃ instantaneously, then closing the microwave reactor for 15-30s, and repeating the on-off cycle for 2-5 times; the whole programmed microwave heating process is carried out under the atmosphere of inert gas.
2. 2. The preparation method of the high-dispersion cobalt-based catalyst according to claim 1, which is characterized by comprising the steps of placing multi-wall carbon nanotubes in mixed acid consisting of nitric acid and sulfuric acid, carrying out reflux reaction under heating, cooling, carrying out suction filtration, washing to neutrality, carrying out vacuum drying to obtain carbon oxide nanotubes, calcining the carbon oxide nanotubes under NH 3 atmosphere, naturally cooling, calcining under inert gas atmosphere, and naturally cooling again to obtain the nitrogen-defect carbon nanotubes.
3. 3. The method for preparing a highly dispersed cobalt-based catalyst according to claim 2, wherein the volume ratio of nitric acid to sulfuric acid is 1 (2-3); and/or the temperature of the reflux reaction is 70-80 ℃ and the time is 4-6h.
4. 4. The method for preparing a highly dispersed cobalt-based catalyst according to claim 2, wherein when the carbon oxide nanotubes are calcined under an NH 3 atmosphere, the flow rate of NH 3 gas is 200 mL/min, the calcination temperature is 500 ℃, the incubation time is 2h, and the temperature rise rate is 5 ℃/min; and/or when the calcination is carried out under the inert gas atmosphere, the flow rate of the inert gas is 200 mL/min, the calcination temperature is 800-900 ℃, the heat preservation time is 1h, and the temperature rising rate is 5 ℃/min.
5. 5. The method for preparing the high-dispersion cobalt-based catalyst according to claim 1, wherein the step of forming the pre-assembled composite by molecular self-assembly in an organic solvent comprises the steps of dissolving the nitrogen-deficient carbon nanotubes and the cobalt tetra-carboxyl phthalocyanine in an organic solvent according to a mass ratio of 1 (1.2-1.8), performing ultrasonic dispersion, magnetically stirring, and rotationally evaporating to remove the organic solvent to obtain the pre-assembled composite.
6. 6. A highly dispersed cobalt-based catalyst prepared according to the preparation method of any one of claims 1 to 5.
7. 7. Use of the highly dispersed cobalt-based catalyst according to claim 6 for the treatment of organic waste water difficult to degrade by advanced oxidation treatment, wherein the organic waste water difficult to degrade by advanced oxidation treatment is selected from waste water containing lomefloxacin hydrochloride, waste water containing tetracycline hydrochloride and/or waste water containing dye-based organic matters.

Description

High-dispersion cobalt-based catalyst and preparation method and application thereof Technical Field The invention belongs to the technical field of cobalt-based catalysts, and particularly relates to a high-dispersion cobalt-based catalyst, and a preparation method and application thereof. Background Currently, common methods for preparing highly dispersed cobalt-based catalysts (Co-Cat) include wet impregnation-pyrolysis, chemical vapor deposition, electrochemical displacement, and the like. In recent years, research has been initiated to explore the application of microwave heating methods in the preparation of monoatomic catalysts (SACs), for example, literature （Single-Atom Cobalt Supported on NCNTs as Bifunctional Electrocatalysts Synthesized by Microwave-Assisted Treatment for Zn-Air Batteries,Industrial & Engineering Chemistry Research,2023,62（35）,13848-13854） reports that monoatomic cobalt catalysts can be prepared on nitrogen-doped carbon nanotubes only in 90 seconds by microwave-assisted treatment of cobalt porphyrin and nitrogen-doped carbon nanotubes. The method aims at realizing the dispersion of metal atoms by utilizing the characteristics of rapidness, uniformity and energy conservation of microwave heating. Although the above microwave method exhibits a certain potential, it has significant drawbacks when used for preparing high-performance highly dispersed cobalt-based catalysts, particularly for the treatment of refractory antibiotic wastewater: (1) The metal atoms are easy to agglomerate, the reduction rate of inorganic cobalt salt (such as cobalt nitrate) in a microwave field is extremely high, but the synergy of the reduction and the anchoring process is difficult to accurately control, so that the probability of metal atoms migration and agglomeration into nano particles is high, and the formation rate of dispersed sites is low. (2) The interaction between the precursor and the carrier is weak, and the simple physical mixing is difficult to ensure that the metal precursor and the carbon carrier have strong interaction at the molecular level. During microwave rapid heating, cobalt species that are not firmly immobilized will first be reduced and have high mobility, which is one of the root causes of agglomeration. (3) The active site has a single structure and is ambiguous that the coordination environment of the finally formed cobalt active center (such as Co-N 4) is highly dependent on the inherent nitrogen species on the surface of the carrier by using an inorganic salt precursor, so that the precise regulation and optimization are difficult, and the catalytic activity and selectivity of the catalyst to specific pollutants (such as lomefloxacin hydrochloride) are not ideal. (4) Although the method has high universality and mediocre performance, the conventional microwave preparation method is simple, but the key problems cannot be solved, so that the performance of the prepared catalyst is often inferior to that of the catalyst prepared by a complex pyrolysis method, the advantages of the catalyst are limited to 'quick', the 'high efficiency' is difficult to realize, and the practical application value of the catalyst is limited. The reason for these problems is that the nature of microwave heating is bulk heating, which is global to the activation of reactants, lacking the control of serialization and regionalization of the critical step of "anchor-reduction" of the metal precursor. Disclosure of Invention In order to solve the technical problems, the invention provides a high-dispersion cobalt-based catalyst and a preparation method and application thereof. In order to achieve the above purpose, the present invention provides the following technical solutions: The invention provides a preparation method of a high-dispersion cobalt-based catalyst, which takes cobalt tetra-carboxyl phthalocyanine (CoPc-COOH) and nitrogen-defect carbon nanotubes (ND-CNTs) as raw materials, forms a pre-assembled compound through molecular self-assembly in an organic solvent, and then carries out programmed microwave heating on the pre-assembled compound to obtain the high-dispersion cobalt-based catalyst; the programmed microwave heating is divided into three stages of heating, the power of the second stage heating is larger than that of the first stage heating, and the power of the third stage heating is larger than that of the second stage heating. How to create enough and uniformly distributed anchor points on the carrier in advance during the rapid course of microwave heating has been a challenge to those skilled in the art. In order to solve the problems, the invention provides a cobalt organometallic precursor (cobalt tetra-carboxyl phthalocyanine), the molecular structure of which has excellent microwave absorption characteristics and preset anchoring sites. According to the invention, through controllable oxidation and subsequent treatment, an anchoring site rich in specific nitrogen defects i