Search

CN-121974339-A - Expanded graphite prepared by microwave field coupling perchloric acid intercalation and preparation method thereof

CN121974339ACN 121974339 ACN121974339 ACN 121974339ACN-121974339-A

Abstract

The invention provides an expanded graphite prepared by microwave field coupling perchloric acid intercalation and a preparation method thereof, wherein the preparation method comprises the steps of mixing graphite with perchloric acid solution to form a homogeneous intercalation precursor, thus obtaining a mixed solution I; and carrying out directional radiation on the mixed solution II in a microwave field to realize directional migration of an intercalation agent and instant expansion of a graphite layer, thereby obtaining the expanded graphite. The preparation method disclosed by the invention can be used for rapidly realizing the expansion of graphite, the expansion effect is obviously improved, the whole process flow is simple, the production energy consumption is low, the reaction process is mild, the process conditions are easy to control, and the expanded graphite with high expansion capacity can be prepared within 5-10 minutes. The expansion volume of the expanded graphite prepared by the invention is 150-800 mL/g, and the expanded graphite has few structural defects, extremely low oxygen-containing functional groups and good electric conductivity.

Inventors

  • LIU BO
  • YANG YANG
  • SUN HONGJUAN
  • XIE JINGXIU
  • ZHANG TAO

Assignees

  • 西南科技大学

Dates

Publication Date
20260505
Application Date
20260127

Claims (10)

  1. 1. A method for preparing expanded graphite by microwave field coupling perchloric acid intercalation, which is characterized by comprising the following steps: (1) Mixing graphite with perchloric acid solution to form a homogeneous intercalation precursor, thus obtaining a mixed solution I; (2) Standing the mixed solution I to finish perchloric acid molecule pre-intercalation to obtain a mixed solution II; (3) And (3) carrying out directional radiation on the mixed solution II in a microwave field to realize the directional migration of the intercalation agent and the instant expansion of the graphite layer, thereby obtaining the expanded graphite.
  2. 2. The method for preparing expanded graphite by microwave field coupling perchloric acid intercalation according to claim 1, wherein the dosage of graphite and perchloric acid solution is 1 g:0.1-4 mL in terms of solid-to-liquid ratio.
  3. 3. The method for preparing expanded graphite by microwave field coupling perchloric acid intercalation according to claim 1, wherein the molar concentration of the perchloric acid solution is 6-12 mol/L.
  4. 4. The method for preparing expanded graphite by microwave field coupling perchloric acid intercalation according to claim 1, wherein the standing temperature in the step (2) is 10-60 ℃.
  5. 5. The method for preparing expanded graphite by microwave field coupling perchloric acid intercalation according to claim 1, wherein the standing time in the step (2) is 10-180 s.
  6. 6. The method for preparing expanded graphite by microwave field coupling perchloric acid intercalation according to claim 1, wherein the power of the directional radiation in the step (3) is 500-1000 w, and the time is 10-180 s.
  7. 7. The method for preparing expanded graphite by microwave field-coupled perchloric acid intercalation according to claim 1, wherein the graphite comprises at least one of flake graphite, microcrystalline graphite and spherical graphite.
  8. 8. The method for preparing expanded graphite by microwave field coupling perchloric acid intercalation according to claim 1, wherein the ash content of the graphite is less than or equal to 0.5wt%.
  9. 9. The method for preparing expanded graphite by microwave field coupling perchloric acid intercalation according to claim 1, wherein the median particle diameter of the graphite is 40-180 meshes, and the specific surface area is 2-8 m 2 /g.
  10. 10. The expanded graphite is characterized by being prepared by the method for preparing the expanded graphite by microwave field coupling perchloric acid intercalation according to any one of claims 1-9, and the expanded volume of the expanded graphite is 150-800 mL/g.

Description

Expanded graphite prepared by microwave field coupling perchloric acid intercalation and preparation method thereof Technical Field The invention relates to the technical field of graphite deep processing, in particular to expanded graphite prepared by microwave field coupling perchloric acid intercalation and a preparation method thereof. Background Under the background of the current technological progress, graphite and its derivatives show wide application prospects in various fields of energy storage, catalytic carriers, environmental protection and the like due to their excellent physical and chemical characteristics. In particular to expanded graphite, which has great potential in the application of high-performance electrode materials such as super capacitors, lithium ion batteries and the like by virtue of excellent conductivity, thermal stability and chemical stability. With the rapid development of the graphene industry, the expanded graphite is used as a key precursor for graphene production, and the efficient preparation technology of the expanded graphite has become a focus of attention in the industry. However, the conventional preparation method of the expanded graphite mainly depends on a sulfuric acid and nitric acid system, and has inherent defects that (1) sulfur residues release SO x pollutants in a high-temperature application process, (2) a heavy metal-containing oxidant such as KMnO 4、K2Cr2O7 needs to be introduced in the preparation process to generate toxic byproducts such as Cr 6+、Mn7+, (3) intercalation reaction needs to be carried out at a high temperature of 60-120 ℃ for 6-24 hours and then puffing treatment is carried out at a high temperature of 900-1200 ℃, and (4) a large amount of acid waste water is generated in a multi-step water washing process, SO that the environment is burdened. In order to solve the problems, the prior art attempts to adopt a chlorine intercalation system to improve and replace sulfuric acid with perchloric acid, thereby realizing the preparation of sulfur-free expanded graphite. The Chinese patent with the application number 03122338.9 discloses a preparation method of sulfur-free low-ash high-purity expanded graphite, which comprises the steps of mixing natural crystalline flake graphite, nitric acid, acetic anhydride and perchloric acid according to the mass ratio of the natural crystalline flake graphite to the nitric acid to the acetic anhydride, wherein the perchloric acid=1:0.5-1.0:1-2:3-7, reacting for 30-120 minutes at the reaction temperature of 30-50 ℃, preparing the acidified graphite, washing with water, drying, dipping with mixed acid of hydrochloric acid and hydrofluoric acid, deacidifying, drying again, and puffing at 900-1100 ℃ to obtain the sulfur-free low-ash high-purity expanded graphite. Although the method can prepare high-quality expanded graphite, the solid-liquid ratio is as high as 1:3.5-10, and hydrochloric acid/hydrofluoric acid secondary purification is needed to be matched, so that the problem of acid pollutant treatment is still faced. Chinese patent application number 201610964766.0 discloses a microwave chemical preparation method of micro-scale sulfur-free expanded graphite. The method comprises the steps of mixing graphite with a composite oxidant and an intercalation agent, reacting for 10-100 minutes at 20-100 ℃, flushing with deionized water until the pH is neutral, drying, and carrying out microwave treatment for 5-60 seconds at the power of 500-1200W to obtain the sulfur-free expanded graphite with the expansion volume of 24 mL/g. The method simplifies the puffing process by introducing microwave technology, but has relatively small expansion volume which is far lower than the 200mL/g standard required by high-end application. The Chinese patent with the application number 201911400932.4 discloses a preparation method of low-temperature sulfur-free and heavy metal-free expandable graphite. The method comprises the steps of mixing flake graphite with perchloric acid solution at the temperature of-25 ℃ to 30 ℃ to obtain primary expandable graphite, adding alcohol into the primary expandable graphite, and uniformly stirring to obtain the expandable graphite. Puffing at 420-1100 ℃ to obtain the sulfur-free and heavy metal-free expanded graphite, wherein the volume of the expanded graphite is 280-800 mL/g. According to the method, the puffing volume is increased to 280-800 mL/g, but a large amount of organic solvent is required, the preparation time is long, the puffing temperature is high and is required to be 420-1100 ℃, and double pressure of solvent recovery and energy consumption exists. Chinese patent application number 201510992663.0 discloses a low temperature preparation method of sulfur-free expandable graphite. According to the method, natural crystalline flake graphite is mixed with potassium permanganate according to the mass percentage of the natural crystalline flake graphite, wherein the ratio of the