CN110803687A

CN110803687A - Preparation method of surface-wrinkled carbon nitride material

Info

Publication number: CN110803687A
Application number: CN201810886806.3A
Authority: CN
Inventors: 姜炜; 李东楠; 谈玲华; 郝嘎子; 胡玉冰; 肖磊; 柯香; 黎博; 李蔡伟
Original assignee: Nanjing University of Science and Technology
Current assignee: Nanjing University of Science and Technology
Priority date: 2018-08-06
Filing date: 2018-08-06
Publication date: 2020-02-18

Abstract

The invention discloses a preparation method of a surface-wrinkled carbon nitride material. Said process fully milled g-C₃N₄And (3) dispersing the powder in a sodium hydroxide solution, then stirring and reacting at 60 +/-10 ℃, carrying out intermittent ultrasonic treatment during the reaction, dialyzing to remove excessive sodium hydroxide after the reaction is finished, and centrifuging to obtain the surface-wrinkled carbon nitride material. g-C prepared by the process of the invention₃N₄The modified material has a fold shape, has a larger specific surface area, releases more active sites, shows a better catalytic effect in the thermal decomposition of ammonium perchlorate, and greatly advances the pyrolysis peak of the thermal decomposition of ammonium perchlorate from 443 ℃ to 338 ℃.

Description

Preparation method of surface-wrinkled carbon nitride material

Technical Field

The invention belongs to the technical field of energetic material preparation, and relates to surface-wrinkled carbon nitride (sfg-C)₃N₄) A method for preparing the material.

Background

Graphite phase carbon nitride (g-C)₃N₄) As a novel inorganic non-metal semiconductor, the catalyst has good thermal stability, acid and alkali resistance and chemical stability, and has wide application prospect in the field of catalysis. Furthermore, g-C₃N₄The preparation process is simple, has no metal elements, has low cost and is beneficial to realizing industrial production. However, g-C prepared by conventional thermal polycondensation₃N₄The specific surface area is small and is 8.0m²/g(Wang K,Li Q,Liu B,et al.Sulfur-doped g-C₃N₄withenhanced photocatalytic CO2-reduction performance[J]Applied Catalysis B: Environmental,2015,176: 44-52.). Too low a specific surface area results in fewer exposed active sites and inhibits catalytic activity, so researchers have used a series of modification methods to increase g-C₃N₄And certain achievements are achieved, such as structural modification, morphology control, element doping, semiconductor coupling and the like. Particularly in the aspect of shape control, the shape of the catalyst represents an exposed crystal face, and the size of the specific surface area and the number of active sites are influenced, so that the shape is one of the key factors influencing the catalytic performance of the material. Thus synthesizing g-C with special morphology₃N₄Has great significance in the field of catalysis.

Ammonium Perchlorate (AP) is a commonly used oxidizer in solid composite propellants and also is a high-energy component of the solid composite propellants, the proportion of the Ammonium Perchlorate (AP) in the propellants is about 70 percent, and the thermal decomposition characteristic of the Ammonium Perchlorate (AP) is one of important factors influencing the combustion performance of the propellants. Researches show that most of metal simple substances, metal oxides and compounds thereof have catalytic effect on the thermal decomposition of ammonium perchlorate, and can reduce the activation energy of the decomposition of the ammonium perchlorate and improve the thermal decomposition rate of the ammonium perchlorate. But the environmental-friendly inorganic non-metal catalyst g-C is considered from the aspects of environmental protection and cost reduction₃N₄In the presence of a catalytic amine perchlorateHas attracted extensive attention, wherein g-C with special morphology is synthesized₃N₄It is an important direction to increase the specific surface area and active sites thereof to improve the catalytic effect on ammonium perchlorate.

Disclosure of Invention

The invention aims to provide a preparation method of a carbon nitride material with surface wrinkles. The method takes graphite phase carbon nitride as a raw material, modifies the raw material by sodium hydroxide solution and is assisted by ultrasonic treatment to prepare the surface fold carbon nitride (sfg-C) with larger specific surface area and more active sites₃N₄)。

In order to achieve the purpose, the technical scheme of the invention is as follows:

the preparation method of the surface-wrinkled carbon nitride material comprises the following steps:

and (2) placing the graphite-phase carbon nitride powder in 1-3 mol/L sodium hydroxide solution, stirring and reacting at 60 +/-10 ℃, carrying out intermittent ultrasonic treatment in the reaction process, dialyzing after the reaction is finished, removing the residual sodium hydroxide, adding water for diluting, carrying out ultrasonic dispersion, centrifuging, and drying to obtain the surface-wrinkled carbon nitride material.

Preferably, the reaction time is 6-12 h, the interval time is 2-4 h and the ultrasonic dispersion time is 0.5-1 h in the intermittent ultrasonic treatment process.

Preferably, the ultrasonic dispersion time is 10-20 min.

Preferably, the rotating speed of the centrifugation is 9000-10000 rpm, and the centrifugation time is 10-15 min.

Compared with the prior art, the invention has the following advantages:

using sodium hydroxide solution for g-C₃N₄The modification and the auxiliary ultrasonic treatment are carried out, so that the flat surface of the material becomes wrinkled and the block-shaped material becomes flaky, the material obtains larger specific surface area and more active centers, the effect of catalyzing the thermal decomposition of the ammonium perchlorate is effectively improved, and the pyrolysis peak of the thermal decomposition of the ammonium perchlorate is greatly advanced from 443 ℃ to 338 ℃ and is advanced by 105 ℃.

Drawings

FIG. 1 shows sfg-C prepared in example 1₃N₄And g-C₃N₄XRD profile of (a).

In FIG. 2, g-C₃N₄(a) SEM images of comparative example 1(b), example 1(c), example 2(d), example 3(e) and comparative example 2 (f).

FIG. 3 is g-C₃N₄sfg-C from example 1, comparative example 2₃N₄Thermal decomposition profile of catalytic ammonium perchlorate.

Detailed Description

The invention is further described below with reference to examples and figures. The following examples are only for illustrating the technical solutions of the present invention more clearly, and the protection scope of the present invention is not limited thereby.

Example 1 preparation of surface-wrinkled carbon nitride Material

(1) 0.5g g-C₃N₄Placing the mixture into 20ml of 3mol/L sodium hydroxide solution, stirring the mixture for 12 hours under the condition of 70 ℃ water bath, taking the mixture out every 4 hours for ultrasonic treatment, wherein the ultrasonic treatment lasts for 1 hour.

(2) Taking out the reaction product in the step (1), putting the reaction product in an MD44 dialysis bag (with molecular weight cutoff of 3500), and dialyzing to remove excessive sodium hydroxide until the solution is neutral;

(3) and (3) placing the completely dialyzed product in the step (2) into 80ml of deionized water for ultrasonic dispersion for 20min, and then centrifuging the solution in a high-speed centrifuge at 10000rpm for 15 min.

(4) Putting the precipitate obtained in the step (3) after centrifugation into a freeze dryer for drying to obtain a product sfg-C₃N₄；

sfg-C prepared in example 1₃N₄After scanning the material with an X-ray diffractometer, see FIG. 1, a scanning electron micrograph is shown in FIG. 2 (c).

Example 2 preparation of surface-wrinkled carbon nitride Material

(1) 0.5g g-C₃N₄Placing the mixture into 20ml of 2mol/L sodium hydroxide solution, stirring the mixture for 9 hours under the condition of water bath at the temperature of 60 ℃, taking the mixture out every 3 hours, and carrying out ultrasonic treatment for 1 hour.

(3) and (3) placing the completely dialyzed product in the step (2) into 80ml of deionized water for ultrasonic dispersion for 15min, and then centrifuging the solution in a high-speed centrifuge at 10000rpm for 10 min.

sfg-C prepared as in example 2₃N₄A scanning electron micrograph of the material is shown in FIG. 2 (d).

Example 3 preparation of surface-wrinkled carbon nitride Material

(1) 0.5g g-C₃N₄Placing the mixture into 20ml of 1mol/L sodium hydroxide solution, stirring the mixture for 6 hours under the condition of water bath at the temperature of 50 ℃, taking the mixture out every 2 hours, and carrying out ultrasonic treatment for 0.5 hour.

(3) the product completely dialyzed in step (2) was placed in 80ml of deionized water for 10min by ultrasonic dispersion, and then the above solution was centrifuged at 9000rpm for 15min in a high-speed centrifuge.

sfg-C prepared as in example 3₃N₄A scanning electron micrograph of the material is shown in figure 2 (e).

Comparative example 1

This comparative example is essentially the same as example 1, except that the concentration of the sodium hydroxide solution is 0.2 mol/L. As shown in FIG. 2(b), the treated g-C in the carbon nitride material obtained was observed₃N₄The original block structure is stripped into a lamellar structure, but the concentration of the sodium hydroxide solution is too low, so that the wrinkling phenomenon is not obvious.

Comparative example 2

This comparative example is essentially the same as example 1, except that the concentration of the sodium hydroxide solution is 8 mol/L. The carbon nitride material thus obtained is shown in FIG. 2(f), and it can be seen from the graph that g-C is caused by an excessively high sodium hydroxide concentration₃N₄Are broken down into small particles by excessive reaction.

EXAMPLE 4 use of catalysis of Ammonium Perchlorate (AP) thermal decomposition

Respectively taking g-C₃N₄sfg-C prepared in example 1₃N₄0.02g of the product of comparative example 1 and comparative example 2 and 0.98g of AP are added into ethanol together and stirred, mixed evenly, and after drying, 2-3mg of a sample is taken for DSC test, and the test conditions are as follows: nitrogen atmosphere, flow rate: 50ml/min, heating rate 10 ℃/min, temperature range: 30-500 ℃. The test results are shown in FIG. 3, sfg-C₃N₄The high-temperature decomposition temperature for catalyzing the AP decomposition is 338 ℃, compared with the high-temperature decomposition temperature of 443 ℃ for catalyzing the pure AP thermal decomposition, the high-temperature decomposition catalyst effectively reduces the temperature required by the high-temperature decomposition, has good catalytic performance, and is similar to g-C₃N₄Compared with catalytic performance at 357 ℃, the catalytic performance is also improved to a small extent.

Claims

1. The preparation method of the surface-wrinkled carbon nitride material is characterized by comprising the following steps of:

2. The preparation method according to claim 1, wherein the reaction time is 6-12 h.

3. The preparation method according to claim 1, wherein the interval time is 2-4 h and the ultrasonic dispersion time is 0.5-1 h in the intermittent ultrasonic treatment process.

4. The preparation method according to claim 3, wherein the ultrasonic dispersion time is 10-20 min.

5. The method according to claim 1, wherein the centrifugation is performed at 9000 to 10000rpm for 10 to 15 min.