CN108439367B

CN108439367B - Method for preparing nano graphite fluoride at low temperature

Info

Publication number: CN108439367B
Application number: CN201810650226.4A
Authority: CN
Inventors: 谢学归; 谢子卓; 张雨寒; 于铉; 谢洁珊
Original assignee: Hubei Zhuoxi Fluorochemical Co ltd
Current assignee: Hubei Zhuoxi Fluorochemical Co ltd
Priority date: 2018-06-22
Filing date: 2018-06-22
Publication date: 2021-09-07
Anticipated expiration: 2038-06-22
Also published as: CN108439367A

Abstract

The invention discloses a method for preparing nano graphite fluoride at low temperature, which comprises the following steps: (1) uniformly mixing nano graphite, citric acid and absolute ethyl alcohol, activating at 120-130 ℃ for 3-5 hours, cooling the temperature of the mixed solution to normal temperature, adding silver fluoride and iodine pentafluoride into the mixed solution, and reacting the mixed solution at 37-52 ℃ for 1.5-2 hours to obtain a reaction product; (2) vacuum-filtering the reaction product to obtain a solid product, adding the solid product into a potassium iodide solution, stirring and filtering, and treating the obtained filter residue to obtain pretreated nano-graphite; (3) and introducing mixed gas of fluorine and nitrogen into the pretreated nano graphite, and reacting at 200-240 ℃ for 1.5-2.5 h to obtain a finished product. Compared with the high-temperature gas phase synthesis method, the method has the advantages that the activity of the graphite intercalation compound is higher than that of graphite, the graphite intercalation compound can react with fluorine gas more easily, the content of the fluorine gas is higher, the reaction temperature is lower, and the safety is higher.

Description

Method for preparing nano graphite fluoride at low temperature

Technical Field

The invention relates to the technical field of non-metallic materials, in particular to a method for preparing nano graphite fluoride at low temperature.

Background

Graphite fluoride is a new material with unique performance, the structure of the graphite fluoride is similar to that of graphene, excellent insulator or semiconductor characteristics are shown, and the control of the band gap of the graphite fluoride can be realized by controlling the size of a graphite fluoride sheet layer. Meanwhile, similar to two-dimensional isotactic polytetrafluoroethylene, the graphite fluoride has a series of unique physicochemical properties such as low surface energy and interlayer energy, high electric polarity, good lubricity, small thermal neutron absorption cross section and the like by introducing fluorine modification, and is increasingly widely applied to the aspects of batteries, nuclear reactors, lubrication, oil removal, pollution prevention, water prevention and the like.

The graphite fluoride synthesis method comprises a high-temperature gas-phase synthesis method, a low-temperature catalytic synthesis method, a solid-phase synthesis method and an electrolysis method, and at present, the domestic method for preparing graphite fluoride mainly adopts the high-temperature gas-phase synthesis method. In the high temperature gas phase method, natural graphite is generally placed in a specific reactor, the graphite needs to be activated at a high temperature before fluorination, nitrogen is introduced for a certain time to ensure a nitrogen atmosphere to remove impurities, and then fluorine-containing gas (such as mixed gas containing fluorine gas or hydrogen fluoride) is introduced to react at 300-600 ℃ for 1-200 hours to obtain the target product. The method is the most mature technology at present, the reaction efficiency is high, and the synthesis process is simple; however, the gas-solid fluorination reaction temperature is high, the reaction is violent, the reaction process is not easy to control, and the heat generated by fluorination can cause local temperature overheating, so that the graphite fluoride is rapidly decomposed and even explodes, and the reaction risk is high.

Disclosure of Invention

The invention aims to overcome the technical defects and provides a preparation method of nano graphite fluoride, which has lower reaction temperature and higher safety.

In order to achieve the technical purpose, the technical scheme of the invention provides a method for preparing nano graphite fluoride at low temperature, which comprises the following steps:

s1, uniformly mixing nano graphite, citric acid and absolute ethyl alcohol, activating the mixed solution at 120-130 ℃ for 3-5 hours in an inert gas atmosphere, cooling the mixed solution to normal temperature, adding silver fluoride and iodine pentafluoride into the mixed solution, heating the mixed solution to 37-52 ℃, and reacting for 1.5-2 hours to obtain a reaction product;

s2, carrying out vacuum filtration on the reaction product to obtain a solid product, adding the solid product into a potassium iodide solution, stirring, filtering the mixed solution, and washing, carrying out suction filtration and vacuum drying on the obtained filter residue to obtain pretreated nano-graphite;

and S3, introducing mixed gas of fluorine and nitrogen into the pretreated nano graphite in an inert gas atmosphere, and reacting at 200-240 ℃ for 1.5-2.5 h to obtain a finished product.

Compared with the prior art, the invention has the beneficial effects that:

1. according to the preparation method of the nano graphite fluoride, citric acid is used as an activating agent, and the nano graphite is activated firstly, so that the nano graphite has more active sites, and the activity of subsequent reaction with fluoride is improved;

2. taking silver fluoride as a catalyst, reacting the nano graphite with iodine pentafluoride at low temperature to obtain pretreated nano graphite, and reacting the pretreated nano graphite with fluorine gas in a fluorine-nitrogen mixed gas to generate graphite fluoride with higher fluorine content;

3. the citric acid is dissolved in the ethanol, so that the nano graphite can be activated, Ag + and I-can be complexed, more fluorine can participate in the reaction, the fluorine content is improved, the nano graphite can be dispersed more uniformly, and the contact area between the nano graphite and the fluorine is increased;

4. compared with a high-temperature gas-phase synthesis method, the nitrogen gas is used for dispersing the fluorine gas more uniformly, so that the concentration of the fluorine gas in unit volume is reduced, the fluorine gas is prevented from reacting with the pretreated nano-graphite seriously locally, and the reaction safety is improved;

5. compared with the high-temperature gas-phase synthesis method, the method has the advantages that the pretreated nano graphite has higher activity than graphite, is easier to react with fluorine gas, and has higher fluorine gas content and lower reaction temperature.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

Example 1:

(1) drying 100g of nano graphite, 2g of silver fluoride and 50g of citric acid at 90 ℃ for 3h, adding the nano graphite and the citric acid into a dried reactor, adding 500ml of absolute ethyl alcohol into the reactor, uniformly stirring and mixing substances in the reactor, introducing nitrogen to exhaust air in the reactor, raising the temperature of a mixed solution in the reactor to 130 ℃, preserving heat for 3.5h, reducing the temperature of the mixed solution in the reactor to normal temperature, adding the silver fluoride and 150g of iodine pentafluoride into the reactor, and stirring and reacting at 40 ℃ for 1.5 h;

(2) carrying out vacuum filtration on the reaction product in the step (1) to obtain a solid substance, adding the solid substance into 100ml of a potassium iodide solution, stirring uniformly, filtering, repeatedly washing filter residues with pure water until the pH value of a washing liquid is 7, carrying out suction filtration, and carrying out vacuum drying on the filter residues to obtain pretreated nano-graphite;

(3) and (3) putting the pretreated nano graphite obtained in the step (2) into a dry reactor, introducing nitrogen into the reactor until air in the reactor is exhausted, introducing a fluorine-nitrogen mixed gas with the fluorine volume concentration of 55% into the reactor, raising the temperature of the reactor to 220 ℃, reacting for 1.5h, stopping heating, and cooling substances in the reactor to obtain the graphite fluoride. The fluorine content in the obtained graphite fluoride was 37.5%.

Example 2:

(1) drying 100g of nano graphite, 2.5g of silver fluoride and 30g of citric acid at 100 ℃ for 2.5h, adding the nano graphite and the citric acid into a dried reactor, adding 500ml of absolute ethyl alcohol into the reactor, uniformly stirring and mixing substances in the reactor, introducing argon to exhaust air in the reactor, raising the temperature of a mixed solution in the reactor to 120 ℃, preserving heat for 3h, reducing the temperature of the mixed solution in the reactor to normal temperature, adding the silver fluoride and 180g of iodine pentafluoride into the reactor, and stirring and reacting at 37 ℃ for 2 h;

(3) and (3) putting the pretreated nano graphite obtained in the step (2) into a dry reactor, introducing argon into the reactor until air in the reactor is exhausted, introducing a fluorine-nitrogen mixed gas with the fluorine volume concentration of 60% into the reactor, raising the temperature of the reactor to 200 ℃, stopping heating after reacting for 2 hours, and cooling substances in the reactor to obtain graphite fluoride. The fluorine content in the obtained graphite fluoride was 42.86%.

Example 3:

(1) drying 100g of nano graphite, 3g of silver fluoride and 45g of citric acid at 100 ℃ for 2.5h, adding the nano graphite and the citric acid into a dried reactor, adding 500ml of absolute ethyl alcohol into the reactor, uniformly stirring and mixing substances in the reactor, introducing argon to exhaust air in the reactor, raising the temperature of a mixed solution in the reactor to 125 ℃, preserving the heat for 4h, reducing the temperature of the mixed solution in the reactor to the normal temperature, adding the silver fluoride and 200g of iodine pentafluoride into the reactor, and stirring and reacting at 45 ℃ for 2 h;

(3) and (3) putting the pretreated nano graphite obtained in the step (2) into a dry reactor, introducing argon into the reactor until the air in the reactor is exhausted, introducing a fluorine-nitrogen mixed gas with the fluorine volume concentration of 65% into the reactor, raising the temperature of the reactor to 230 ℃, stopping heating after reacting for 2 hours, and cooling the substances in the reactor to obtain the graphite fluoride. The fluorine content in the obtained graphite fluoride was 51.22%.

Example 4:

(1) drying 100g of nano graphite, 4g of silver fluoride and 60g of citric acid at 110 ℃ for 2h, adding the nano graphite and the citric acid into a dried reactor, adding 500ml of absolute ethyl alcohol into the reactor, uniformly stirring and mixing substances in the reactor, introducing helium to exhaust air in the reactor, raising the temperature of mixed liquid in the reactor to 120 ℃, preserving the heat for 5h, reducing the temperature of the mixed liquid in the reactor to the normal temperature, adding the silver fluoride and 220g of iodine pentafluoride into the reactor, and stirring and reacting at 52 ℃ for 1.5 h;

(3) and (3) putting the pretreated nano graphite obtained in the step (2) into a dry reactor, introducing helium into the reactor until air in the reactor is exhausted, introducing a fluorine-nitrogen mixed gas with the fluorine volume concentration of 70% into the reactor, raising the temperature of the reactor to 240 ℃, stopping heating after reacting for 2.5 hours, and cooling substances in the reactor to obtain the graphite fluoride. The fluorine content in the obtained graphite fluoride was 49.37%.

The above-described embodiments of the present invention should not be construed as limiting the scope of the present invention. Any other corresponding changes and modifications made according to the technical idea of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A method for preparing nano graphite fluoride at low temperature is characterized by comprising the following steps:

2. The method for preparing nano graphite fluoride at low temperature according to claim 1, wherein the mass ratio of the nano graphite to the silver fluoride to the citric acid to the iodine pentafluoride in the step S1 is 1: 0.02-0.04: 0.3-0.6: 1.5 to 2.2.

3. The method for preparing nano graphite fluoride at low temperature according to claim 2, wherein the mass ratio of the nano graphite to the silver fluoride to the citric acid to the iodine pentafluoride in the step S1 is 1: 0.03: 0.45: 2.0.

4. the method for preparing nano graphite fluoride at low temperature according to claim 1, wherein the step S1 is preceded by drying the nano graphite, the citric acid and the silver fluoride at 90-110 ℃ for 2-3 h.

5. The method for preparing nano graphite fluoride at low temperature according to claim 1, wherein the filter residue is washed in step S2 until the pH of the washing solution is 7.

6. The method for preparing nano graphite fluoride at low temperature according to claim 1, wherein the volume concentration of the fluorine gas in the mixed gas of fluorine and nitrogen in the step S3 is 55-70%.