阅读说明：本技术 一种石墨相氮化碳催化剂的制备方法 (Preparation method of graphite phase carbon nitride catalyst ) 是由 孙剑 贺滨 冯咪 赵丁伟 陈欣妍 张玲 于 2019-10-28 设计创作，主要内容包括：本发明涉及一种采用生物质强化的石墨相氮化碳催化剂制备方法。所述方法包括：1)将前驱体与生物质按照一定的比例加入到水中,磁力搅拌,加热至80℃,直至水分蒸干,得到混合料。2)将步骤(1)所得混合料装入石英坩埚中,用铝箔纸密封,氮气气氛下以加热至500℃～800℃,继续反应2～24h,得到石墨相氮化碳催化剂。该方法使用绿色廉价的可再生生物质原料强化制备石墨相氮化碳催化剂,克服了石墨相氮化碳依靠贵金属沉积、半导体复合、离子掺杂提高其性能,成本高、制备过程复杂、难以大规模制备等缺点。该石墨相氮化碳在用于光催化降解有机污染物时,改进了降解率低、降解速度慢等难题,克服了传统催化剂改进方法中成本高、过程复杂的缺点。(The invention relates to a preparation method of a graphite-phase carbon nitride catalyst strengthened by biomass. The method comprises the following steps: 1) adding the precursor and the biomass into water according to a certain proportion, magnetically stirring, heating to 80 ℃, and evaporating until the water is evaporated to dryness to obtain a mixture. 2) And (2) putting the mixture obtained in the step (1) into a quartz crucible, sealing the quartz crucible by using aluminum foil paper, heating the quartz crucible to 500-800 ℃ under the nitrogen atmosphere, and continuously reacting for 2-24 hours to obtain the graphite-phase carbon nitride catalyst. The method uses the green cheap renewable biomass raw materials to strengthen the preparation of the graphite phase carbon nitride catalyst, and overcomes the defects that the performance of the graphite phase carbon nitride is improved by depending on precious metal deposition, semiconductor compounding and ion doping, the cost is high, the preparation process is complex, the large-scale preparation is difficult, and the like. When the graphite-phase carbon nitride is used for photocatalytic degradation of organic pollutants, the problems of low degradation rate, low degradation speed and the like are solved, and the defects of high cost and complex process in the traditional catalyst improvement method are overcome.)

1. A method for preparing a graphite-phase carbon nitride catalyst, comprising the steps of:

(1) adding the precursor and the biomass into water according to a certain proportion, magnetically stirring, heating to 80 ℃, and evaporating until the water is evaporated to dryness to obtain a mixture;

(2) and (2) putting the mixture obtained in the step (1) into a quartz crucible, sealing the quartz crucible by using aluminum foil paper, heating the quartz crucible to 500-800 ℃ under the nitrogen atmosphere, and continuously reacting for 2-24 hours to obtain the graphite-phase carbon nitride catalyst.

2. The method according to claim 1, wherein the precursor combined with the biomass is selected from any one of urea, melamine, dicyandiamide, thiourea and cyanamide or a combination of at least two thereof.

3. The method of claim 1, wherein the biomass is selected from any one or more of straw, lignin, cellulose, hemicellulose, shrimp shell, crab shell, chitin, starch, alginic acid, wool, silk, and combinations thereof.

4. The method according to claim 1, characterized in that the mass ratio of the precursor to biomass is 100: (0.01-20).

Technical Field

The invention belongs to the field of chemical catalysis, and particularly relates to a preparation method of a graphite phase carbon nitride catalyst.

Background

Graphite phase carbon nitride (g)-C₃N₄) Is a visible light-responsive semiconductor photocatalyst prepared by thermal polymerization of precursors (urea, melamine, dicyandiamide, etc.) in which C, N atoms are sp atoms²The hybrid formation of highly delocalized pi conjugated system has good physical and chemical stability and energy band structure, and has wide application prospect in the fields of photocatalytic degradation of organic pollutants, photolysis of water to produce hydrogen, photo-reduction of carbon dioxide and the like.

At present, graphite phase carbon nitride (g-C)₃N₄) The main preparation methods comprise a high-temperature high-pressure solid phase method, a vapor deposition method, a solvothermal method and a high-temperature thermal polymerization method. But the currently available g-C₃N₄The problems of small specific surface area, easy combination of photo-generated electrons and vacancies, low visible light absorption utilization rate and the like exist in the photocatalysis process, and the practical application of the photocatalysis material is limited. In the prior published documents, noble metal deposition, ion doping, heterojunction composite construction with other semiconductors and other means are often adopted to modify the noble metal, but the cost is high, the flow is complex and the large-scale preparation is difficult.

Disclosure of Invention

In view of the above problems in the prior art, the present invention aims to provide a graphite phase carbon nitride catalyst, a biomass-enhanced preparation method and uses thereof. The method uses cheap, green and nontoxic biomass to assist in synthesizing the graphite-phase carbon nitride catalyst, can prepare the graphite-phase carbon nitride catalyst in an environment-friendly manner, and can overcome the defects that the performance of the traditional catalyst is enhanced by depending on noble metals and other semiconductors, the cost is high, the flow is complex, the large-scale preparation is difficult, and the like. When the catalyst is used for photocatalytic degradation of organic pollutants, the problems of low degradation rate, slow degradation rate, low utilization rate of visible light and the like in the prior art are improved.

The invention provides a preparation method of graphite phase carbon nitride, which comprises the following steps:

(1) adding the precursor and the biomass into water according to a certain proportion, magnetically stirring, heating to 80 ℃, and evaporating until the water is evaporated to dryness to obtain a mixture.

(2) And (2) putting the mixture obtained in the step (1) into a quartz crucible, sealing the quartz crucible by using aluminum foil paper, heating the quartz crucible to 500-800 ℃ under the nitrogen atmosphere, and continuously reacting for 2-24 hours to obtain the graphite-phase carbon nitride catalyst.

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

(1) the biomass used in the invention can be obtained from nature, and is green, nontoxic and cheap.

(2) The method is a method for preparing graphite-phase carbon nitride by biomass reinforcement, wherein in the method, the biomass can increase the nitrogen content on the surface of a catalyst and increase the crystallinity of an active crystal face in the process of precursor polymerization, and meanwhile, the forbidden bandwidth can be reduced and the absorption of visible light can be increased in the synthesis process. Meanwhile, the biomass can be gradually removed in the thermal polymerization process, and the template agent is used, so that the carbon nitride catalyst with high active sites is obtained.

(3) Compared with the traditional noble metal deposition, the method simplifies the preparation process of the catalyst, has low cost and simple operation, and is suitable for mass preparation.

(4) The method adopts the biomass to enhance and improve the photocatalytic activity of the graphite-phase carbon nitride, overcomes the defects of high cost, ion loss in the using process of the catalyst and the like caused by doping with other ions in the traditional method, meets the development requirement of green chemistry, and greatly improves the degradation rate of the biomass-enhanced carbon nitride catalyst on organic pollutants.

Drawings

FIG. 1 is a scanning electron micrograph of graphite-phase carbon nitride obtained in step (2) of example 1 of the present invention.

FIG. 2 is a scanning electron micrograph of graphite-phase carbon nitride obtained in step (2) of example 2 of the present invention.

FIG. 3 is a scanning electron micrograph of graphite-phase carbon nitride obtained in step (2) of example 3 of the present invention.

FIG. 4 is a scanning mirror image of graphite-phase carbonitride obtained in step (2) of example 4 of the present invention.

FIG. 5 is a scanning mirror image of graphite-phase carbonitride obtained in step (2) of example 5 of the present invention.

FIG. 6 is a scanning mirror image of graphite-phase carbonitride obtained in step (2) of example 6 according to the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail below with reference to the accompanying drawings and 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.

The embodiment of the invention provides a preparation method of graphite-phase carbon nitride, which comprises the following steps:

(1) adding the precursor and the biomass into water according to a certain proportion, magnetically stirring, heating to 80 ℃, and evaporating until the water is evaporated to dryness to obtain a mixture.

(2) And (2) putting the mixture obtained in the step (1) into a quartz crucible, sealing the quartz crucible by using aluminum foil paper, heating the quartz crucible to 500-600 ℃ in a nitrogen atmosphere, and continuously reacting for 2-24 hours to obtain the graphite-phase carbon nitride catalyst.

In the invention, the biomass material contains C, N, H elements, can be well combined with the precursor, increases the nitrogen content on the surface of the carbon nitride, and is easy to remove after calcination without affecting the crystal structure of the catalyst.

Specifically, the biomass refers to: directly from an organism or an extract of an organism. Mainly comprises any one or more of corn straw, lignin, cellulose, hemicellulose, shrimp shell, crab shell, chitin, starch, alginic acid, silk, wool and wool keratin, for example, the following components: chitin, lignin, cellulose and cellulose, cellulose and hemicellulose, glucose and chitin, etc., preferably chitin.

In the present invention, the method for self-polymerizing the precursor at high temperature to form carbon nitride is the prior art, and the person skilled in the art can refer to the method disclosed in the prior art to prepare the carbon nitride, for example, according to the following method:

and (2) putting the precursor (such as urea) into a quartz crucible, sealing the quartz crucible by using aluminum foil paper, heating the quartz crucible to 500-800 ℃ under the nitrogen atmosphere, and heating and roasting the quartz crucible for 2-24 hours to obtain the graphite-phase carbon nitride catalyst.

As a preferred technical scheme of the method, the mixing mode in the step (1) is as follows: firstly, the biomass is placed in a container, then the mixed liquid of the biomass and water is added, and the ultrasonic treatment is carried out for 60 min.

Preferably, the precursor in step (1) comprises any one of urea, melamine, dicyandiamide, thiourea and monocyanide or a combination of at least two of the two (the formed precursor-biomass mixture is urea-chitin, urea-cellulose, urea-glucose and the like), and preferably urea.

Preferably, the mass ratio of the precursor to the biomass in the step (1) is 100: (0.01-10), for example, 100:0.02, 100:0.06, 100:0.2, 100:0.5, 100:0.7, 100:0.9, 100:1, 100: 10. 100:15, 100:20, etc. If the mass ratio is more than 100:20, the biomass content in the system is too high, the crystallinity of graphite phase carbon nitride is reduced, and the catalytic activity is reduced; if the mass ratio is less than 100:0.02, the biomass content is too low, and the carbon nitride is difficult to be correspondingly regulated and controlled. More preferably, the mass ratio of the precursor to the biomass is 100 (0.06-10).

Preferably, the heating rate in step (2) is 2 ℃/min to 15 ℃/min, such as 2 ℃/min, 5 ℃/min, 7 ℃/min, 10 ℃/min, 12 ℃/min, 15 ℃/min, preferably 10 ℃/min to 15 ℃/min.

Preferably, the heating temperature in step (2) is 500 to 600 ℃, for example, 500 ℃, 520 ℃, 530 ℃, 550 ℃, 560 ℃, 580 ℃, and the like, preferably 550 to 580 ℃.

Preferably, the roasting time in the step (2) is 2h to 12h, such as 2h, 3h, 5h, 6.5h, 7h, 7.5h, 8h and the like.

As a further preferred technical solution of the method of the present invention, the method comprises the steps of:

(1) adding the precursor and the biomass into water according to the proportion of 100 (0.06-10), performing ultrasonic treatment for 1h, performing magnetic stirring, heating to 80 ℃ until the water is evaporated to dryness, and thus obtaining a mixture.

(2) And (2) putting the mixture obtained in the step (1) into a quartz crucible, sealing the quartz crucible by using aluminum foil paper, heating the mixture to 550-580 ℃ at the heating rate of 10-15 ℃/min in the nitrogen atmosphere, and continuously reacting for 2-12 h to obtain the graphite-phase carbon nitride catalyst.

The following examples illustrate the preparation of the carbon nitride catalyst. The compounds in the following examples can be prepared directly according to the existing methods, but of course, in other examples, they can be directly commercially available, and are not limited thereto.