阅读说明：本技术 一种磷掺杂微孔、中孔和大孔共存等级孔孔隙结构纳米碳球的制备方法 (Preparation method of phosphorus-doped microporous, mesoporous and macroporous coexisting grade pore structure nano carbon spheres ) 是由 王鹏 易钰富 文阳平 廖圣良 司红燕 罗海 贺璐 杨宇玲 张骥 王宗德 陈尚钘 于 2021-05-12 设计创作，主要内容包括：本发明公开了一种磷掺杂微孔、中孔和大孔共存等级孔孔隙结构纳米碳球的制备方法,属于碳材料制备领域。通过一定质量的木聚糖为碳源,引入一定质量聚乙烯吡咯烷酮为软模板和一定容积的硫酸为促碳化剂,在一定温度下水热反应一定时间得到前置物,使用乙醇和水离心清洗,干燥后的前置物和磷酸按一定比例活化,最后在惰性气体保护下的管式炉中煅烧制备微孔、中孔和大孔共存等级孔隙结构纳米碳球。该制备方法制得的碳球均匀分散、可获得等级孔隙结构和纳米尺度,同时具有成本低廉,工序少、操作简易等优点,且制备的碳球可用于催化剂载体制备高性能催化剂、电极材料工业化生产及吸附领域等。(The invention discloses a preparation method of phosphorus-doped microporous, mesoporous and macroporous coexisting grade pore structure nano carbon spheres, and belongs to the field of carbon material preparation. The method comprises the steps of taking xylan with a certain mass as a carbon source, introducing polyvinylpyrrolidone with a certain mass as a soft template and sulfuric acid with a certain volume as a carbonization promoter, carrying out hydrothermal reaction for a certain time at a certain temperature to obtain a precursor, carrying out centrifugal cleaning by using ethanol and water, activating the dried precursor and phosphoric acid according to a certain proportion, and finally calcining in a tubular furnace under the protection of inert gas to prepare the microporous, mesoporous and macroporous coexisting hierarchical pore structure carbon nanospheres. The carbon spheres prepared by the preparation method are uniformly dispersed, can obtain a hierarchical pore structure and a nanoscale, and simultaneously have the advantages of low cost, few processes, simplicity in operation and the like.)

1. A preparation method of phosphorus-doped microporous, mesoporous and macroporous coexisting hierarchical pore carbon nanospheres is characterized by comprising the following steps of:

step 1: preparation of the precursor

The method comprises the steps of taking xylan with a certain mass as a carbon source, introducing different soft template agents with a certain mass and sulfuric acid with a certain volume, carrying out hydrothermal reaction for a certain time at a certain temperature to obtain a precursor, carrying out centrifugal cleaning by using ethanol and water, and drying to obtain a precursor;

step 2: preparation of carbon nanosphere

And (2) activating the precursor obtained in the step (1) and phosphoric acid according to a certain proportion, and finally calcining in a tubular furnace under the protection of inert gas to prepare the phosphorus-doped microporous, mesoporous and macroporous coexisting hierarchical porous carbon nanospheres.

2. The method for preparing the phosphorus-doped microporous, mesoporous and macroporous coexisting grade porous carbon nanospheres according to claim 1, wherein in the step 1, the soft template agent is different surfactants, preferably polyvinylpyrrolidone.

3. The method for preparing the phosphorus-doped microporous, mesoporous and macroporous coexisting graded-pore carbon nanospheres according to claim 1, wherein in the step 1, the mass of xylan is 0.5-2 g; the mass of the polyvinylpyrrolidone is 0.1-0.5 g; the volume of sulfuric acid was 1 mL.

4. The method for preparing the phosphorus-doped microporous, mesoporous and macroporous coexisting graded-pore carbon nanospheres according to claim 1, wherein the hydrothermal reaction temperature in the step 1 is 160 ℃ and the reaction time is 4 hours.

5. The method for preparing phosphorus-doped microporous, mesoporous and macroporous coexisting graded-pore carbon nanospheres according to claim 1, wherein in the step 2, the ratio of the precursor to the phosphoric acid is 1:4, and the inert gas is N₂。

Technical Field

The invention relates to the technical field of carbon material preparation, in particular to a preparation method of phosphorus-doped microporous, mesoporous and macroporous coexisting grade pore structure nano carbon spheres.

Background

Porous Carbon Spheres (PCSs) have received much attention due to their properties of good chemical and thermal stability, adjustable porosity, controllable particle size distribution and excellent electrical conductivity. At present, many examples of PCSs are synthesized by taking phenolic resin, nitrogenous polymer and biomass as carbon sources, and extensive research is carried out on PCSs synthesized by phenolic resin in a controllable manner. Carbon materials with different porosities (micropores, mesopores or hierarchical pores) and different structures (solid spheres, hollow spheres, core-shell spheres or yolk-shell spheres) are obtained by adopting different synthesis methods such as a St baby method, a hard template method, a soft template method, a spray pyrolysis method or microemulsion polymerization. As polyaniline, polypyrrole, polydopamine, polydiaminopyridine and melamine resin have rich N-framework structures, the obtained material contains various N-sites (amino-N, pyrrole-N and pyridine-N) and has good performance in the fields of electrocatalysis and energy storage. Compared with the research work, the inherent non-toxic and renewable characteristics of the biomass and the mild hydrothermal reaction conditions enable the synthesis process of the biomass-derived carbon spheres to be more efficient, economical and environment-friendly. Inspired by the pioneering work of Wang et al (Q Wang, H Li, L Q Chen, X J Huang, Carbon, 2001, 39: 2211-2214), a variety of sugars (glucose, fructose, xylose, and sucrose) have been used to synthesize PCSs. The carbon source is then expanded to furfural, starch, cyclodextrin, chitosan, cellulose and lignocellulose. However, most of PCSs prepared by a direct hydrothermal method are microporous, and the porosity is not developed. Although enhanced by post-activation treatment, some mesopores may even be formed, the resulting material is still predominantly microporous, limiting its range of applications.

In order to realize the structural innovation of the biomass-derived carbon spheres, Titirici et al (M Titirici, A Thomas, M Antonietti, Advanced functional materials, 2007, 17: 1010-1018) first adopted a hard template method. By controlling the hydrophilicity and hydrophobicity of the hard template silica spheres, hollow and mesoporous carbon microspheres are synthesized. In the reports later, the hollow carbon microspheres and the ordered mesoporous carbon nanospheres are prepared by taking the amino-functionalized silica microspheres and the MCM-48 nanospheres as hard templates, or the hollow carbon spheres prepared by taking polystyrene spheres as the hard templates can be directly removed in the high-temperature calcination process, so that the subsequent etching process is avoided. Lu et al (X J Lu, C H Jiang, Y L Hu, H C Zhong, Y ZHao, X C Xu, H Z Liu, Journal of Applied Electrochemistry, 2018, 48: 233-₄)₂Fe(SO4)₂As a pore-foaming agent, the C/FeOx composite ball obtained by acid cleaning can obtain a micro or meso pore structure. Although the method can successfully regulate the structure of the derived biomass PCSs, the mass production and industrialization of the phosphorus-doped carbon spheres are restricted, so that great efforts are still needed to realize a more feasible strategy for controlling the material structure in the hydrothermal process.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provides a preparation method and a preparation method of phosphorus-doped microporous, mesoporous and macroporous coexisting grade pore structure nano carbon spheres, which have the advantages of compact structure, reduced working strength of workers, improved filtrate filtration efficiency, improved medicament component extraction efficiency and simplicity in operation.

The purpose of the invention is realized by the following technical scheme: the method comprises the following steps:

step 1: preparation of the precursor

The method comprises the steps of taking xylan (95%) with a certain mass as a carbon source, introducing a certain mass of surfactants with different properties and a certain volume of sulfuric acid, carrying out hydrothermal reaction for a certain time at a certain temperature to obtain a precursor, carrying out centrifugal cleaning by using ethanol and water, and drying to obtain the precursor.

Step 2: preparation of carbon nanosphere

And (2) activating the precursor obtained in the step (1) and phosphoric acid according to a certain proportion, and finally calcining in a tubular furnace under the protection of inert gas to prepare the phosphorus-doped microporous, mesoporous and macroporous coexisting hierarchical porous carbon nanospheres.

2. The method for preparing the phosphorus-doped microporous, mesoporous and macroporous coexisting grade porous carbon nanospheres according to claim 1, wherein in the step 1, the soft template agent is a different kind of surfactant, preferably polyvinylpyrrolidone.

3. In the step 1, the mass of xylan (95%) is 0.5-2 g; the mass of the polyvinylpyrrolidone is 0.1-0.5 g; the volume of sulfuric acid was 1 mL.

4. In the step 1, the hydrothermal reaction temperature is 433K, and the reaction time is 4 h.

5. In the step 2, the ratio of the precursor to the phosphoric acid is 1:4, and the inert gas is N₂。

In the preparation method of the phosphorus-doped microporous, mesoporous and macroporous coexisting graded-pore carbon nanospheres, xylan (95%) is used as a carbon source, phosphoric acid is simultaneously used as an activating agent and a doping agent, polyvinylpyrrolidone is introduced to obtain microporous, mesoporous and macroporous coexisting graded pore structures and nanoscale carbon spheres, and surfactants such as: f127, P123, thiobetaine 12, sodium dodecyl sulfate and dodecyl trimethyl ammonium chloride can regulate and control the particle size and the pore structure of the carbon spheres.

The invention has the following advantages:

1. the carbon source adopted by the invention is xylan (95%) which comes from natural plants and has strong reproducibility, the preparation cost is low, and the process is simple.

2. The phosphorus-doped carbon spheres prepared by the method have a porous structure with coexisting micropores, mesopores and macropores, and have high dispersibility and nanoscale.

3. The phosphorus-doped hierarchical porous carbon nanospheres prepared by the invention can regulate the particle size and the pore structure by introducing different surfactants, and simultaneously expand the preparation method of biomass-derived porous carbon spheres.

Drawings

FIG. 1 is a phosphorus-doped microporous, mesoporous and macroporous coexisting hierarchical pore structure carbon nanosphere prepared by using polyvinylpyrrolidone as a soft template;

FIG. 2 is a phosphorus-doped carbon microsphere prepared by using F127 as a soft template;

FIG. 3 is a phosphorus-doped carbon microsphere prepared by using P123 as a soft template;

FIG. 4 is a phosphorus-doped carbon microsphere prepared by using sodium dodecyl sulfate as a soft template;

FIG. 5 is a phosphorus-doped carbon microsphere prepared by using sodium dodecyl sulfate as a soft template;

FIG. 6 is a phosphorus-doped carbon microsphere prepared using thiobetaine 12 as a soft template;

FIG. 7 is a phosphorus-doped carbon microsphere prepared by using dodecyl trimethyl ammonium chloride as a soft template.

Detailed Description

The invention will be further described with reference to the accompanying drawings, without limiting the scope of the invention to the following:

example 1

1 g of xylan (95%), 0.3 g of polyvinylpyrrolidone and 1mL of sulfuric acid were dissolved in 60 mL of ultrapure water, and after ultrasonic dissolution, the resulting solution was transferred to a 100 mL polytetrafluoroethylene-lined stainless steel autoclave and subjected to hydrothermal treatment at 433K for 4 hours. Naturally cooling to room temperature, filtering the obtained brown mixture to remove impurities, centrifuging at high speed with ultrapure water and ethanol, repeatedly cleaning to obtain a precursor,dried in a 343K oven. Mixing the precursor and phosphoric acid (the mass ratio is phosphoric acid (85%): precursor = 4: 1), putting the mixture into an oven, drying the mixture at 373K, and finally drying the mixture by using N₂Calcining at 1073K for 4h at 278K/min in a protected tubular furnace to obtain the phosphorus-doped microporous, mesoporous and macroporous coexisting hierarchical pore carbon nanospheres. As shown in fig. 1 and table 1, the prepared carbon spheres have high dispersibility, nanoscale (50-150 nm), spherical morphology, and hierarchical pore structure in which micropores, mesopores, and macropores coexist.

Example 2

1 g of xylan (95%), 0.3 g F127 and 1mL of sulfuric acid were dissolved in 60 mL of ultrapure water, and after ultrasonic dissolution, the resulting solution was transferred to a 100 mL polytetrafluoroethylene-lined stainless steel autoclave and subjected to hydrothermal treatment at 433K for 4 hours. Naturally cooling to room temperature, filtering the obtained brown mixture to remove impurities, centrifuging at high speed by using ultrapure water and ethanol, repeatedly cleaning to obtain a precursor, and drying in a 343K oven. Mixing the precursor and phosphoric acid (the mass ratio is phosphoric acid (85%): precursor = 4: 1), putting the mixture into an oven, drying the mixture at 373K, and finally drying the mixture by using N₂Calcining at 1073K for 4h at 278K/min in a protected tubular furnace to obtain the phosphorus-doped carbon spheres. As shown in fig. 2 and table 1, it can be found that the phosphorus-doped carbon spheres do not have a hierarchical pore structure in which nano-scale and micro-pore, meso-pore and macro-pore coexist, but have a hierarchical pore structure in which micro-pore and meso-pore coexist, and have a micro-scale (0.5-2 μm).

Example 3

1 g of xylan (95%), 0.3 g P123 and 1mL of sulfuric acid were dissolved in 60 mL of ultrapure water, and after ultrasonic dissolution, the resulting solution was transferred to a 100 mL polytetrafluoroethylene-lined stainless steel autoclave and subjected to hydrothermal treatment at 433K for 4 hours. Naturally cooling to room temperature, filtering the obtained brown mixture to remove impurities, centrifuging at high speed by using ultrapure water and ethanol, repeatedly cleaning to obtain a precursor, and drying in a 343K oven. Mixing the precursor and phosphoric acid (the mass ratio is phosphoric acid (85%): precursor = 4: 1), putting the mixture into an oven, drying the mixture at 373K, and finally drying the mixture by using N₂Calcining at 1073K for 4h at 278K/min in a protected tubular furnace to obtain the phosphorus-doped carbon spheres. As shown in fig. 3 and table 1, it can be found that the phosphorus-doped carbon spheres also do not have the nano-scale sumThe hierarchical pore structure where micropores, mesopores and macropores coexist, but the microporous structure as well as the micrometer scale (0.5 to 3 μm).

Example 4

1 g of xylan (95%), 0.3 g of sodium dodecyl sulfate and 1mL of sulfuric acid were dissolved in 60 mL of ultrapure water, and after ultrasonic dissolution, the resulting solution was transferred to a 100 mL polytetrafluoroethylene-lined stainless steel autoclave and subjected to hydrothermal treatment at 433K for 4 hours. Naturally cooling to room temperature, filtering the obtained brown mixture to remove impurities, centrifuging at high speed by using ultrapure water and ethanol, repeatedly cleaning to obtain a precursor, and drying in a 343K oven. Mixing the precursor and phosphoric acid (the mass ratio is phosphoric acid (85%): precursor = 4: 1), putting the mixture into an oven, drying the mixture at 373K, and finally drying the mixture by using N₂Calcining at 1073K for 4h at 278K/min in a protected tubular furnace to obtain the phosphorus-doped carbon spheres. As shown in FIG. 4 and Table 1, it can be found that the phosphorus-doped carbon spheres also do not have a hierarchical pore structure in which nano-scale and micro-and meso-and macro-pores coexist, but have a micro-pore structure and a wider micro-scale (1-6 μm)

Example 5

1 g of xylan (95%), 0.3 g of sodium dodecyl sulfate and 1mL of sulfuric acid were dissolved in 60 mL of ultrapure water, and after ultrasonic dissolution, the resulting solution was transferred to a 100 mL polytetrafluoroethylene-lined stainless steel autoclave and subjected to hydrothermal treatment at 433K for 4 hours. Naturally cooling to room temperature, filtering the obtained brown mixture to remove impurities, centrifuging at high speed by using ultrapure water and ethanol, repeatedly cleaning to obtain a precursor, and drying in a 343K oven. Mixing the precursor and phosphoric acid (the mass ratio is phosphoric acid (85%): precursor = 4: 1), putting the mixture into an oven, drying the mixture at 373K, and finally drying the mixture by using N₂Calcining at 1073K for 4h at 278K/min in a protected tubular furnace to obtain the phosphorus-doped carbon spheres. As shown in FIG. 5 and Table 1, it can be found that the phosphorus-doped carbon spheres also do not have a hierarchical pore structure in which nano-scale and micro-and meso-and macro-pores coexist, but have a micro-pore structure and a wider micro-scale (1-6 μm)

Example 6

Dissolving 1 g of xylan (95%), 0.3 g of thiobetaine 12 and 1mL of sulfuric acid in 60 mL of ultrapure water, dissolving the solution by ultrasonic wave, and transferring the obtained solution to a containerThe reaction mixture was transferred to a 100 mL stainless steel autoclave lined with Teflon and subjected to hydrothermal treatment at 433K for 4 hours. Naturally cooling to room temperature, filtering the obtained brown mixture to remove impurities, centrifuging at high speed by using ultrapure water and ethanol, repeatedly cleaning to obtain a precursor, and drying in a 343K oven. Mixing the precursor and phosphoric acid (the mass ratio is phosphoric acid (85%): precursor = 4: 1), putting the mixture into an oven, drying the mixture at 373K, and finally drying the mixture by using N₂Calcining at 1073K for 4h at 278K/min in a protected tubular furnace to obtain the phosphorus-doped carbon spheres. As shown in fig. 6 and table 1, it can be found that the phosphorus-doped carbon spheres also do not have a hierarchical pore structure in which nano-scale and micro-and meso-and macro-pores coexist, but a micro-pore structure and a wider micro-scale (1-6 μm).

TABLE 1

Example 7

1 g of xylan (95%), 0.3 g of dodecyltrimethylammonium chloride and 1mL of sulfuric acid were dissolved in 60 mL of ultrapure water, and after ultrasonic dissolution, the resulting solution was transferred to a 100 mL polytetrafluoroethylene-lined stainless steel autoclave and subjected to hydrothermal treatment at 433K for 4 hours. Naturally cooling to room temperature, filtering the obtained brown mixture to remove impurities, centrifuging at high speed by using ultrapure water and ethanol, repeatedly cleaning to obtain a precursor, and drying in a 343K oven. Mixing the precursor and phosphoric acid (the mass ratio is phosphoric acid (85%): precursor = 4: 1), putting the mixture into an oven, drying the mixture at 373K, and finally drying the mixture by using N₂Calcining at 1073K for 4h at 278K/min in a protected tubular furnace to obtain the phosphorus-doped carbon spheres. As shown in fig. 7 and table 1, it can be found that the phosphorus-doped carbon spheres also do not have a hierarchical pore structure in which nano-scale and micro-pore, meso-pore and macro-pore coexist, but a microporous structure and a larger micro-scale (2-6 μm) are found in that the phosphorus-doped carbon spheres also do not have a hierarchical pore structure in which nano-scale and micro-pore, meso-pore and macro-pore coexist.

The phosphorus-doped carbon spheres prepared in the embodiments 1 to 7 have controllable particle size and pore structure, simple preparation process, low cost and environmental friendliness.

Finally, it should be noted that: 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 changes may be made in the embodiments and/or equivalents thereof without departing from the spirit and scope of the invention. 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.