CN-118106012-B - Monoatomic and nanoparticle composite catalyst, preparation and application

Abstract

The invention relates to a metal monoatomic and nanoparticle composite catalyst and a preparation method thereof. The metal salt, dicyandiamide and urea are reasonably proportioned, and the simple two-step pyrolysis method is adopted to prepare the high-load single-atom and nano-particle composite catalyst. The single-atom and nano-particle composite catalyst obtained by the invention can construct a large number of active sites, remarkably improves the catalytic activity and stability of the catalyst, is used for degrading sulfonamide organic pollutants, quinolone organic pollutants and tetracycline organic pollutants or depolymerizing lignin, has excellent catalytic activity, and has higher degradation or depolymerization effects than the catalysts reported at present.

Inventors

• LV YUANCAI
• HU YIHUI
• ZENG QIBIN
• GUO HONG
• LIU YIFAN

Assignees

• 福州大学

Dates

Publication Date

20260508

Application Date

20240307

Claims (7)

1. 1. A method for preparing a monoatomic and nanoparticle composite catalyst, which is characterized by comprising the following steps: Preparing a metal compound, namely dissolving 0.1-2 mmol of metal salt, 1-8 mmol of dicyandiamide and 0.1-10 mmol of urea in ultrapure water according to the mass amount, and carrying out heat treatment after fully mixing, wherein the temperature of the heat treatment is 100-400 ℃ and the time of the heat treatment is 1-6 hours to obtain the metal compound; And preparing the monoatomic and nanoparticle composite catalyst, namely fully grinding the metal composite, calcining the metal composite, wherein the calcining is performed in a hydrogen atmosphere, the calcining temperature is 300-800 ℃, the calcining time is 2-6 h, and naturally cooling to obtain the monoatomic and nanoparticle composite catalyst.
2. 2. The method of claim 1, wherein the metal salt is at least one metal of cobalt, copper, nickel, iron, and manganese in the form of at least one salt of nitrate, sulfate, hydrochloride, and acetate.
3. 3. The method according to claim 1, wherein the temperature is raised to 300-800 ℃ at a rate of 1-10 ℃ min -1 during the calcination.
4. 4. A monoatomic and nanoparticle composite catalyst prepared by the method of any one of claims 1 to 3.
5. 5. A method for oxidative degradation of organic pollutants using the single-atom and nanoparticle composite catalyst prepared by the preparation method of any one of claims 1 to 3.
6. 6. The method of claim 5, wherein the organic contaminants comprise sulfonamide organic contaminants, quinolone organic contaminants, and/or tetracycline organic contaminants.
7. 7. A method of using the monoatomic and nanoparticle composite catalyst prepared by the preparation method of any one of claims 1 to 3 for lignin catalytic depolymerization.

Description

Monoatomic and nanoparticle composite catalyst, preparation and application Technical Field The invention belongs to the technical field of catalyst preparation, and particularly relates to a metal single-atom and nanoparticle composite catalyst and a preparation method thereof. Background The catalyst plays a vital role in chemical reaction, and can obviously improve the reaction rate and reduce the reaction activation energy, thereby realizing more efficient energy utilization and material conversion. The most practical and common metal supported catalysts, in which the size of metal particles has a significant influence on the catalyst performance, have atomic active centers uniformly dispersed on a carrier in a chemically bonded manner as the size of metal particles is reduced to an atomic level, can maximally utilize metal atoms and ensure stability under many severe reaction conditions, and can enhance the selectivity and reactivity of the catalyst. However, single-atom catalysts also have certain limitations in that they contain only one specific type of active site, and when the reaction involves a multi-step reaction with multiple intermediates, it is difficult for the single-atom catalyst to break the linear scale relationship between the different intermediates. In addition, to maintain a single atom configuration, the loading of metal sites on the single atom catalyst must be limited to prevent spatial agglomeration, which may result in a sacrifice in the overall catalytic performance of the catalyst despite the higher activity of the single atoms. Recently, single-atom catalysts modified with nanoscale metal particles (e.g., nanoparticles or nanoclusters) have become one potential solution to break through the above limitations, particularly in reactions requiring multiple metal atom active sites. The monoatomic and nanoparticle composite catalysts exhibit different electronic and geometric structures compared to monoatomic catalysts. Notably, when supported on a carrier, the single-atom and nanoparticle composite catalysts generally exhibit irregular polyhedral shapes, with different coordination environments of atoms at these positions, resulting in different adsorption strengths of reactants. Meanwhile, the metal monoatomic catalyst has extremely high atom utilization rate due to high dispersion of metal atoms, unique electronic structure and surface property, and excellent catalytic activity, and the nanoparticle catalyst has larger specific surface area and rich active sites, so that the catalytic reaction can be efficiently carried out on the nanoscale. The existing preparation method of the metal monoatomic and nanoparticle composite catalyst mainly comprises a physical synthesis method, a chemical synthesis method, a biological synthesis method and the like, and the problems of complex operation, high cost, poor catalyst stability and the like often exist. Among these methods, the physical synthesis method generally requires high temperature and high pressure conditions, and the chemical synthesis method has problems of complicated synthesis steps and complex residues, and the biological synthesis method is environment-friendly but the preparation process is time-consuming and difficult to control. In addition, the literature reports that the problems of aggregation, inactivation and the like of the metal single-atom and nano-particle composite catalyst prepared by the prior method are easy to occur in the reaction process, and the long-term stability and the catalytic performance of the catalyst are reduced. For example, some processes require the use of expensive equipment and high purity starting materials, which increases the cost of the preparation, while others require high temperatures or pressures, which not only increase the difficulty of operation, but can also affect the structure and performance of the catalyst. In addition, due to the special properties of metal monoatoms and nanoparticles, they are susceptible to agglomeration or loss during the preparation process, resulting in reduced activity of the catalyst. Therefore, the development of a novel method for preparing the composite catalyst of the metal monoatoms and the nano particles, which is simple and convenient to operate and low in cost, can prepare the composite catalyst with high stability and high activity, and has important significance for promoting the development of catalyst technology and improving the efficiency of catalytic reaction. Disclosure of Invention In view of the technical problems, the application provides a single-atom and nanoparticle composite catalyst to solve the problems of high preparation cost, unstable catalytic activity, poor catalytic performance, low carrier loading capacity and the like in the prior art. The preparation method of the single-atom and nano-particle composite catalyst provided by the application has the characteristics of simple operation steps, conventional equipment