CN109319765B

CN109319765B - Preparation method and application of graphene synthesized by biomass combustion

Info

Publication number: CN109319765B
Application number: CN201710638066.7A
Authority: CN
Inventors: 王黎东; 费维栋; 苑亦男; 刘兆远
Original assignee: Harbin Institute of Technology
Current assignee: Harbin Institute of Technology
Priority date: 2017-07-31
Filing date: 2017-07-31
Publication date: 2022-06-07
Anticipated expiration: 2037-07-31
Also published as: CN109319765A

Abstract

The invention discloses a preparation method and application of graphene synthesized by biomass combustion, and relates to the field of solid waste treatment and the technical field of chemical synthesis. The method adopts a combustion synthesis method to prepare the graphene by using biomass; the prepared graphene can be used as a supercapacitor material. According to the invention, the graphene is prepared by resource utilization of biomass with low utilization value commonly existing in nature, and the production cost of industrially synthesized graphene is reduced, so that the graphene has important potential application in the fields of catalysts, composite materials, electrochemistry and the like. The method has the advantages of simple process, cheap raw materials, very simple equipment requirement and operation, easy batch production and increase of a reasonable resource utilization method of biomass materials.

Description

Preparation method and application of graphene synthesized by biomass combustion

Technical Field

The invention belongs to the technical field of chemical synthesis; in particular to a preparation method for synthesizing graphene by biomass combustion.

Background

Biomass refers to various organisms formed through photosynthesis, including various animals and plants, microorganisms, agricultural byproducts, and the like. The crop by-product yield is huge every year in China, wherein the amount of wheat, rice, corn straws and the like is as much as five hundred billion tons. The wood dust and sawdust in the forestry byproducts, and the quantity of the fruit shells and the fruit peels in the food industry are increasing day by day. If the agriculture and forestry byproducts and the food wastes are incinerated and directly buried, the environmental pollution and the great waste of resources are undoubtedly caused. Therefore, with the increasing shortage of fossil energy and the increasing increase of environmental pollution, the rational utilization of biomass resources is receiving extensive attention of researchers

If the carbon product can be prepared by processing biomass such as wood, forestry and agricultural wastes, various plants, animal wastes, expired and deteriorated grains and food, urban and industrial wastes and the like, the method is a good solution.

At present, a method for preparing graphene from biomass is mainly a high-temperature carbonization method, the realization steps are simple, mass production is realized, and graphene with good production quality is a research purpose all the time, but the high-temperature carbonization method usually needs gas protection and an activation process, the process is relatively complex, and the cost is relatively high. Compared with the existing combustion synthesis method which utilizes biomass as a carbon source, the existing combustion synthesis method has relatively high cost and increases the cost of large-scale production. The reducing agent is used too singly.

Disclosure of Invention

The invention provides a preparation method for synthesizing graphene by biomass combustion, which solves the technical problems of low resource utilization rate, low relative added value of prepared products and poor economic benefit in the current application of biomass. The invention takes common low-cost agricultural and forestry wastes such as wood chips, straws and the like as raw materials, and adopts a combustion synthesis method to prepare the graphene. The invention avoids burning and burying the agricultural and forestry byproducts, and changes waste into valuable. And the problems of complex preparation process, high cost and the like of the graphene are solved, and important potential application of the graphene in the fields of catalysts, composite materials, energy storage and the like is exerted.

The invention carries out the cost reduction of the carbon source on the existing patent of preparing the graphene by using the carbon source as the raw material, adopts the biomass material which is ubiquitous in the nature and lacks the utilization value as the carbon source, and is beneficial to waste utilization and large-scale production.

In order to solve the technical problems, the preparation method for synthesizing the graphene by biomass combustion comprises the following steps: and after uniformly mixing the biomass powder and a reducing agent, carrying out combustion synthesis reaction under a combustion synthesis atmosphere, and then carrying out acid washing, water washing and drying treatment in sequence to obtain the graphene.

Further limiting, 0.5-5 parts of biomass powder and 1 part of reducing agent are uniformly mixed according to parts by weight.

Further limiting, the biomass powder is one or any combination of plant roots, plant stems, plant leaves, plant peels, plant fruits, plant husks, plant seeds, expired or deteriorated grains, expired or deteriorated foods, fishbones, fish scales, algae, wood chips and waste paper; the combination is carried out according to any ratio;

the stems of the plants are one or any combination of several of straws, wheat straws, bean straws, cotton straws and bagasse, and the combination is carried out according to any ratio;

the leaves of the plants are one or the combination of any several of wheat straw, rice straw and leaves, and the combination is carried out according to any ratio;

the pericarp of the plant is one or any combination of a plurality of rice hulls, shaddock peels, coconut shells, walnut shells, peanut shells, chestnut shells, rice shells and betel nut shells, and the combination is carried out according to any ratio;

the fruits of the plants are one or any combination of several of bananas, apples, pineapples and grapes, and the combination is carried out according to any ratio;

the plant shells are one or any combination of a cherry pit and a sunflower seed shell, and the combination is carried out according to any ratio.

Further limiting, the reducing agent is one or any combination of several of metal magnesium, metal aluminum and metal calcium, and the combination is carried out according to any ratio;

further limiting, the combustion synthesis atmosphere is one or a mixture of any of argon, helium, carbon dioxide, nitrogen and air, and the air pressure is controlled to be 0.001 Pa-20 Mpa;

wherein, under the condition that the combustion synthesis atmosphere contains oxygen but does not contain carbon dioxide, the volume of the oxygen accounts for 5 to 21 percent of the total volume of the combustion synthesis atmosphere gas, and the total mole number of the oxygen accounts for 40 to 50 percent of the total mole number of the metal of the reducing agent;

under the condition that the combustion synthesis atmosphere contains oxygen and carbon dioxide at the same time, the total volume of the oxygen accounts for 0.001-21% of the total volume of the combustion synthesis atmosphere gas, the sum of the mole numbers of the oxygen and the carbon dioxide accounts for 40-60% of the total mole number of the reducing agent metal, and the rest is carried out according to any ratio.

Further limited, the pickling is to soak the pickling solution with hydrochloric acid with the mass percentage of 5-37% until the pH value of the pickling solution is less than 5 and is kept unchanged.

Further defined, the reducing agent has a purity of 95 to 99.999 mass percent; the average particle diameter is 0.01mm-5 mm.

Further defined, the biomass powder has an average particle size of 0.01mm to 5 mm.

Further limiting, the powder mixing is carried out in a powder mixing machine, the stirring speed of the powder mixing machine is controlled to be 100 rpm-10000 rpm, the powder is fully stirred until the powder is uniform, and the time for mixing the powder is generally 0.01h-4 h.

Further limiting, the combustion synthesis reaction is a high-pressure combustion synthesis reaction or a normal-pressure combustion synthesis reaction, and the pressure of the combustion synthesis reaction is 0.01 Pa-20 MPa, and a local electric heating ignition or ignition agent ignition mode is adopted.

Further defined, drying or freeze-drying is carried out under normal pressure or in vacuum.

The graphene prepared by the method is applied as a supercapacitor material.

The invention provides a preparation method for synthesizing graphene powder by combusting biomass materials. Firstly, uniformly mixing a reducing agent and a biomass material, then igniting mixed powder in air, wherein the reducing agent firstly reacts with the gas, the combustion reaction transfers heat to the surrounding biomass material in a combustion wave mode, and the speed of the combustion wave is 0.1-25ms^-1The velocity of the combustion wave is not equal and the driving force for the combustion wave is the release of thermal energy to form the combustion reaction, and no further heat supply is required after initiation. Then the biomass material absorbs the heat released by combustion to decompose carbon dioxide, the carbon dioxide and the reducing agent continuously react to generate a combustion synthesis crude product, the generated heat further decomposes the adjacent biomass material, and the reaction is continuously carried out until the reducing agent in the reaction system completely reacts. Because a large amount of heat is violently released by the combustion reaction, a large amount of gas generated by the decomposition of the biomass is sprayed out in the reaction process to leave a large amount of pore structures, and thus the high-quality graphene with a three-dimensional structure can be prepared. The atmosphere may contain oxygen, which functions as: (1) reacting with magnesium to release heat and promote the graphitization of the organic matter; (2) reacts with organic matter to produce carbon dioxide, which can react with magnesium to produce graphene.

The invention adopts biomass as raw material, avoids pollution caused by waste incineration and direct landfill, changes waste into valuable, has low price and provides a method for resource utilization of biomass material.

The combustion synthesis process has the advantages of simple equipment and operation, no need of introducing special gas, short reaction time and easy batch production, and avoids large energy consumption caused by heating of the tubular furnace by using the energy released by the combustion reaction.

According to the invention, carbon in the biomass material is effectively utilized as a carbon source, the biomass material is instantaneously decomposed to release gas, and the prepared graphene has a good micro-porous structure.

According to the graphene prepared by the method disclosed by the invention, a scanning electron microscope photo of a product prepared by an embodiment shows that the surface of the graphene has a spatial three-dimensional structure and is rich in wrinkles, and the surface of the graphene prepared by wood chips has a spatial three-dimensional structure and is rich in wrinkles, and the graphene has flaky graphene with large size and a multi-level hole structure. Some of the graphene prepared by adopting the straws have large-size lamellar structures, the graphene sheets are thin, and some of the graphene sheets also have microcosmic graphene frameworks with dense frameworks. Meanwhile, a peak diagram obtained by the Raman spectrum shows that the graphene prepared by the method has fewer defects and is graphene with better quality.

Drawings

FIG. 1 shows the surface morphology of the powder obtained in examples 1, 2 and 3.

FIG. 2 shows the Raman spectra of the product powders obtained in examples 1, 2 and 3.

Fig. 3 shows XRD characterization results of the product powders obtained in examples 1, 2 and 3.

FIG. 4 shows the results of the specific surface area of the product powders obtained in examples 1, 2 and 3.

FIG. 5 is a summary chart of electrochemical test results of the product powders obtained in examples 1, 2, and 3, wherein the results are (a) cyclic voltammetry curves at 5mV/s sweep rate, (b) rate capability at different sweep rates, (c) constant current charge and discharge curves at 0.1A/g current density, and (d) specific capacitance at different current densities.

Detailed Description

Example 1: the preparation method for synthesizing graphene by biomass combustion in the embodiment is as follows:

weighing 1.5 parts of wood chips and 1 part of magnesium powder according to the mass parts, uniformly mixing, placing the mixed powder in a crucible combustion synthesis device, controlling the combustion synthesis atmosphere to be air and the air pressure to be 1.01Mpa, heating and igniting the powder mixed by the wood chips and the magnesium powder by using a resistance wire in the atmosphere, cooling a combustion product to room temperature, then pickling the combustion product by using 20% hydrochloric acid until the pH value of a pickling solution is less than 5 and keeps unchanged, then filtering and washing the product until the washing solution is neutral, and drying the washing solution in a vacuum oven at 120 ℃ for 12 hours.

Fig. 1 shows that when the graphene powder prepared as described above is observed under an electron scanning microscope, the form of the graphene powder is as shown in fig. 1 (a). As can be seen from fig. 1(a), the graphene prepared by the method has a spatial three-dimensional structure on the surface, is rich in wrinkles on the surface, has a plurality of flake-like graphenes with large sizes, and has a multi-level pore structure.

Fig. 2 shows that Raman spectroscopy was performed on the graphene powder obtained as described above, and the results are shown in fig. 2. As can be seen from FIG. 2, the prepared graphene powder is few-layer graphene, and the 2D peak of the Raman spectrum is 2692cm^-1Peak position 2730 cm relative to graphite^-1Obviously move to a low wave band; its D peak (1343 cm)^-1) Peak to G (1583 cm)^-1) The graphene has low strength and fewer surface defects, and is graphene with better quality.

Fig. 3 shows that XRD characterization of the obtained graphene powder showed the result shown in fig. 3. As can be seen from fig. 3, a broadened peak near 23 to 26 ° corresponds to the (002) crystal plane of graphene, a small amount of graphite with good crystallization is doped, and 42.5 ° corresponds to the (100) crystal plane of graphene, so that the prepared powder is graphene. The other hetero-peaks are peaks of MgO coated in graphene sheets.

As shown in fig. 4, the specific surface area of the graphene powder obtained as described above was measured, and as a result, it can be seen from fig. 4(a) that the product was an IV isothermal adsorption curve. The specific surface of the product was 353.98m²Per g, pore volume of 0.7932cm^3/g, the average pore diameter is 8.9635nm, which shows that the graphene prepared by the lignin combustion synthesis method has very high performanceHigh specific surface area, and is an ideal material for application of supercapacitors and the like.

As can be seen from FIG. 5, the specific capacitance of the graphene powder obtained as described above was measured to be 92.1F/g at a current density of 0.1A/g, as measured by an electrochemical test.

Example 2: the preparation method for synthesizing graphene by biomass combustion in the embodiment is as follows:

taking 1.35 parts of straw core and 1 part of magnesium powder according to the mass parts, uniformly mixing, placing the mixed powder in a combustion synthesis device, controlling the combustion synthesis atmosphere to be air and the air pressure to be 1.01Mpa, heating and igniting the mixed powder of the straw core and the magnesium powder by using a resistance wire in the atmosphere, cooling a combustion product to room temperature, then pickling the combustion product by using 20% hydrochloric acid until the pH value of a pickling solution is less than 5 and keeps unchanged, then filtering and washing the product until a washing liquid is neutral, and drying for 12 hours in a vacuum oven at 120 ℃.

Fig. 1 shows that when the graphene powder prepared as described above is observed under an electron scanning microscope, the form of the graphene powder is as shown in fig. 1 (b). As can be seen from fig. 1(b), the graphene prepared by this method has a spatial three-dimensional structure on the surface, and the surface is rich in wrinkles, and has some flake graphene with a large size.

Fig. 2 shows that Raman spectroscopy was performed on the graphene powder obtained as described above, and the results are shown in fig. 2. As can be seen from FIG. 2, the prepared graphene powder is few-layer graphene, and the 2D peak of the Raman spectrum is 2675cm^-1Peak position 2730 cm relative to graphite^-1Obviously move to a low wave band; its D peak (1348 cm)^-1) And peak G (1585 cm)^-1) The strength is equivalent, which indicates that graphene is prepared.

FIG. 4 shows that the graphene powder obtained as described above was measuredThe results are shown in FIG. 4, and it can be seen from FIG. 4(a) that the product is an IV isothermal adsorption curve. The specific surface of the product was 349.09m²Per g, pore volume of 0.831cm³The average pore diameter is 9.5221nm, which shows that the graphene prepared by the lignin combustion synthesis method has high specific surface area and is an ideal material for application such as super capacitors.

As can be seen from FIG. 5, the specific capacitance of the graphene powder measured by the electrochemical test was 53.87F/g at a current density of 0.1A/g at the maximum.

Example 3: the preparation method for synthesizing graphene by biomass combustion in the embodiment is as follows:

taking 1.5 parts of straw bark and 1 part of magnesium powder according to the mass parts, uniformly mixing, placing the mixed powder in a combustion synthesis device of the combustion synthesis device, wherein the combustion synthesis atmosphere is air, the air pressure is controlled to be 1.01Mpa, heating and igniting the powder mixed by lignin and the magnesium powder by using a resistance wire in the atmosphere, cooling a combustion product to room temperature, then pickling the combustion product by using 20% hydrochloric acid until the pH value of a pickling solution is less than 5 and keeps unchanged, then filtering and washing the product until a washing solution is neutral, and drying for 12 hours in a vacuum oven at 120 ℃.

Fig. 1 shows that when the graphene powder prepared as described above is observed under an electron scanning microscope, the form of the graphene powder is as shown in fig. 1 (c). As can be seen from fig. 1(c), the graphene prepared by this method has a spatial three-dimensional structure on the surface, and the surface is rich in wrinkles, and has some flake graphene with a large size.

Fig. 2 shows that Raman spectroscopy was performed on the graphene powder obtained as described above, and the results are shown in fig. 2. As can be seen from FIG. 2, the prepared graphene powder is few-layer graphene, and the 2D peak of the Raman spectrum is 2685cm^-1Peak position 2730 cm relative to graphite^-1Obviously move to a low wave band; its D peak (1335 cm)^-1) And peak G (1589 cm)^-1) The strength is equivalent, and the graphene is good in quality.

Fig. 3 shows that XRD characterization of the obtained graphene powder showed the result shown in fig. 3. As can be seen from fig. 3, a broadened peak near 23 to 26 ° corresponds to the (002) crystal plane of graphene, a small amount of graphite with good crystallization is doped, and 42.5 ° corresponds to the (100) crystal plane of graphene, so that the prepared powder is graphene. The other miscellaneous peaks are peaks of MgO coated in graphene sheets.

As shown in fig. 4, the specific surface area of the graphene powder obtained as described above was measured, and as a result, it can be seen from fig. 4(a) that the product was an IV isothermal adsorption curve. The specific surface of the product was 342.65m²Per g, pore volume of 0.6967cm³The average pore diameter is 8.133nm, which shows that the graphene prepared by the lignin combustion synthesis method has high specific surface area and is an ideal material for application of supercapacitors and the like.

As can be seen from FIG. 5, the specific capacitance of the graphene powder obtained as described above was 117.3F/g at a current density of 0.1A/g, as measured by an electrochemical test.

Claims

1. The preparation method for synthesizing graphene by biomass combustion is characterized by comprising the following steps:

uniformly mixing biomass powder and a reducing agent, carrying out combustion synthesis reaction under a certain atmosphere condition, and carrying out acid washing, water washing and drying treatment in sequence to obtain graphene; the atmosphere synthesized by combustion is air;

wherein the biomass powder is wood chips or straws;

uniformly mixing 1.35-1.5 parts of biomass powder and 1 part of reducing agent in parts by weight;

the reducing agent is metal magnesium;

the pressure of the atmosphere synthesized by combustion is controlled to be 1.01 MPa.

2. The preparation method of graphene synthesized by burning biomass according to claim 1, wherein the acid washing is performed by soaking the acid washing solution with hydrochloric acid with the mass percentage of 5% -37% until the pH value of the acid washing solution is less than 5 and is kept unchanged.

3. The preparation method of graphene synthesized by combusting biomass according to claim 1, wherein the mass purity of the reducing agent is 95-99.999%.

4. The preparation method of graphene synthesized by combusting biomass according to claim 3, wherein the average particle diameter of the reducing agent is 0.01-5 mm.

5. The preparation method of graphene synthesized by combusting biomass according to claim 1, wherein the average particle size of the biomass powder is 0.01mm-5 mm.

6. Use of the graphene prepared by the method of any one of claims 1 to 5 as a supercapacitor material.