Method for preparing biomass graphene by using cellulose as raw material

Abstract

A method for preparing biomass graphene by using cellulose as a raw material includes preparing a catalyst solution, carrying out ionic coordination and high-temperature deoxidization on cellulose and a catalyst so as to obtain a precursor, carrying out thermal treatment and pre-carbonization, and carrying out acid treatment and drying to obtain the graphene. The graphene is uniform in morphology with a single-layer or multi-layer two-dimensional layered structure having a dimension of 0.5 m to 2 m, and an electric conductivity of 25000 S/m to 45000 S/m. The graphene can be applied to electrode materials of super capacitors and lithium ion batteries, and can also be added to resin and rubber as an additive so as to improve physical properties of the resin and the rubber.

Claims

1. A method for preparing biomass graphene using cellulose as a raw material, comprising: preparing a catalyst solution, wherein a catalyst is added to distilled water to form a first mixture, the first mixture is stirred for 10 to 30 min to form a catalyst solution, in which the ratio of catalyst to solvent is within 2:100 to 35:100; preparation a precursor, wherein a biomass cellulose is added to the catalyst solution to form a second mixture, the second mixture is stirred for 1 to 4 hours then deoxidized at a high temperature and dried to obtain a precursor, in which the mass ratio of cellulose to solvent is within 3:100 to 40:100; heat-treating the precursor including a pre-carbonization step and a secondary carbonization step, wherein the pre-carbonization step includes heating the precursor to within 220 to 650 C. at 10 to 20 C./min for 1 to 6 hours in an atmosphere including at least one of nitrogen gas, argon gas, and hydrogen gas to obtain a pre-carbonized precursor, and the secondary carbonization step includes heating the pre-carbonized precursor to within 900 to 1650 C. at 5 to 16 C./min for 4 to 15 hours to obtain a heat-treated product; and obtaining graphene, wherein the heat-treated product is acid-treated, centrifuged, washed with distilled water to neutral, and dried at 80-110 C. to obtain graphene.

2. The method of claim 1, wherein the biomass cellulose is at least one of cellulose extracted from corncobs, corn stalks, sorghum stalks, soybean stalks, stems or leaves of cattail, coconut shells, and palm shells.

3. The method of claim 1, wherein the catalyst is at least one of FeCl.sub.2, FeCl.sub.3, K.sub.3[Fe(CN).sub.6], and K.sub.4[Fe(CN).sub.6].

4. The method of claim 1, wherein the first mixture is stirred for 13 to 25 minutes, and the ratio of catalyst to solvent being within 3:100 to 25:100.

5. The method of claim 4, wherein the first mixture is stirred for 15 to 20 minutes, and the ratio of catalyst to solvent being within 4:100 to 15:100.

6. The method of claim 1, wherein the second mixture is stirred for 2 to 3 hours, and the deoxidation is conducted at one of 110 to 205 C. for 6 to 16 hours and 110 to 170 C. for 5 minutes to 2 hours at 3-9 kW in microwave strength.

7. The method of claim 6, wherein the deoxidation is conducted at one of 120 to 180 C. for 8 to 12 hours and 130 to 160 C. for 20 minutes to 1.5 hours at 4 to 7 kW in microwave strength.

8. The method of claim 1, wherein the pre-carbonization step includes heating the precursor to within 300 to 450 C. at 11 to 16 C./min for 2 to 5 hours, and the secondary carbonization step includes heating the pre-carbonized precursor to within 1000 to 1550 C. at 5 to 12 C./min for 5 to 10 hours.

9. The method of claim 8, wherein the pre-carbonization step includes heating the precursor to within 330 to 420 C. at 12 to 16 C./min for 2 to 4 hours, and the secondary carbonization step includes heating the pre-carbonized precursor to within 1050 to 1450 C. at 6 to 12 C./min for 5 to 8 hours.

10. The method of claim 1, wherein acid-treating is performed with acid comprising at least sulfuric acid, perchloric acid, and nitric acid, and drying is performed between 90 to 105 C.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a diagram illustrating a method of preparing graphene, in accordance with various embodiments of the disclosure.

(2) FIG. 2 is a transmission electron micrograph of graphene prepared according to Example 12.

(3) FIG. 3 is a Raman spectrum of graphene prepared according to Example 12.

DESCRIPTION

(4) Examples in accordance with the present disclosure will be described in detail below with reference to the accompanying drawings. It should be noted that technical features described in the following examples or combinations thereof should not be considered to be isolated, and instead they can be combined with each other to achieve the desired technical effects.

(5) FIG. 1 is a diagram illustrating a method of preparing graphene, in accordance with various embodiments of the disclosure, comprises the following steps: S1 preparing a catalyst solution; S2: carrying out ionic coordination of cellulose and catalyst, and high-temperature deoxidization, so as to obtain a precursor; S3: carrying out thermal treatment; S4: carrying out acid treatment and drying; and S5: obtaining graphene.

Example 1

(6) The present example for preparing biomass graphene using cellulose as a raw material is carried out by the following steps:

(7) Step 1: Preparation of a catalyst solution: 18 g of FeCl.sub.2 (solute) is added to 100 ml of distilled water (solvent) and the mixture is stirred for 25 min to obtain a homogeneous catalyst solution, in which the ratio of solute to solvent is 18:100;

(8) Step 2: Preparation of a precursor: cellulose is added to the catalyst solution obtained in step 1, and the mixture is stirred for 2 h and then reacted for 10 h at a temperature of 140 C., then the mixture is deoxidized and dried to obtain a precursor, in which the mass ratio of cellulose to solvent is 26:100;

(9) Step 3: Heat treatment: To pre-carbonize, the precursor obtained in step 2 is heated to 280 C. at a heating rate of 10 C./min in a nitrogen gas, argon gas or hydrogen gas atmosphere to be pre-carbonized for 3 h; To carry out secondary carbonization, the pre-carbonized product is heated to 1050 C. at a heating rate of 8 C./min for heat treatment for 6 h;

(10) Step 4: Acid treatment, water-washing and drying: the product obtained in step 3 is acid-treated, centrifuged and then washed with distilled water to neutral, and then dried at 105 C. to obtain graphene.

(11) The transmission electron micrograph of the graphene prepared in the present Example 1 is similar to that of Example 12, as shown in FIG. 2. The Raman spectrum of the graphene prepared in Example 1 is similar to that of the graphene prepared in Example 12, as shown in FIG. 3.

(12) Graphene prepared by the present example has a uniform size, a single layer or multi-layer two-dimensional layered structure, a size of 0.5-2 m, and a conductivity of above 25000-45000 S/cm. The yield of graphene in this example is above 99.9%.

Example 2

(13) This example differs from Example 1 in that the cellulose described in step 1 is cellulose extracted from soybean straw biomass.

(14) The transmission electron micrograph of the graphene prepared in the present Example 2 is similar to that of Example 12, as shown in FIG. 2. The Raman spectrum of the graphene prepared in the present Example 2 is similar to that of the graphene prepared in Example 12, as shown in FIG. 3.

(15) Graphene prepared by the present example has a uniform size, a single layer or multi-layer two-dimensional layered structure, a size of 0.5-2 m, and a conductivity of above 25000-45000 S/cm. The yield of graphene in this example is above 99.9%.

Example 3

(16) This example differs from Example 2 in that the catalyst described in step 1 is a mixture of FeCl.sub.2 and FeCl.sub.3.

(17) The transmission electron micrograph of the graphene prepared in the present Example 3 is similar to that of Example 12, as shown in FIG. 2. The Raman spectrum of the graphene prepared in the present Example 3 is similar to that of the graphene prepared in Example 12, as shown in FIG. 3.

(18) Graphene prepared by the present example has a uniform size, a single layer or multi-layer two-dimensional layered structure, a size of 0.5-2 m, and a conductivity of above 25000-45000 S/cm. The yield of graphene in this example is above 99.9%.

Example 4

(19) This example differs from Example 3 in that the deoxidation at a high temperature in step 2 is conducted at a temperature of 175 C. for 7 h or at a microwave strength of 4.5 kW and a temperature of 150 C. for 1 h.

(20) The transmission electron micrograph of the graphene prepared in the present Example 4 is similar to that of Example 12, as shown in FIG. 2. The Raman spectrum of the graphene prepared in the present Example 4 is similar to that of the graphene prepared in Example 12, as shown in FIG. 3.

(21) Graphene prepared by the present example has a uniform size, a single layer or multi-layer two-dimensional layered structure, a size of 0.5-2 m, and a conductivity of above 25000-45000 S/cm. The yield of graphene in this example is above 99.9%.

Example 5

(22) This example differs from Example 4 in that the cellulose described in step 1 is cellulose extracted from sorghum stalk biomass.

(23) The transmission electron micrograph of the graphene prepared in the present Example 5 is similar to that of Example 12, as shown in FIG. 2. The Raman spectrum of the graphene prepared in the present Example 5 is similar to that of the graphene prepared in Example 12, as shown in FIG. 3.

(24) Graphene prepared by the present example has a uniform size, a single layer or multi-layer two-dimensional layered structure, a size of 0.5-2 m, and a conductivity of above 25000-45000 S/cm. The yield of graphene in this example is above 99.9%.

Example 6

(25) This example differs from Example 5 in that the cellulose described in step 1 is cellulose extracted from the stems or leaves of cattail biomass.

(26) The transmission electron micrograph of the graphene prepared in the present Example 6 is similar to that of Example 12, as shown in FIG. 2. The Raman spectrum of the graphene prepared in the present Example 6 is similar to that of the graphene prepared in Example 12, as shown in FIG. 3.

(27) Graphene prepared by the present example has a uniform size, a single layer or multi-layer two-dimensional layered structure, a size of 0.5-2 m, and a conductivity of above 25000-45000 S/cm. The yield of graphene in this example is above 99.9%.

Example 7

(28) This example differs from Example 6 in that the catalyst described in step 1 is K.sub.3[Fe(CN).sub.6].

(29) The transmission electron micrograph of the graphene prepared in the present Example 7 is similar to that of Example 12, as shown in FIG. 2. The Raman spectrum of the graphene prepared in the present Example 7 is similar to that of the graphene prepared in Example 12, as shown in FIG. 3.

(30) Graphene prepared by the present example has a uniform size, a single layer or multi-layer two-dimensional layered structure, a size of 0.5-2 m, and a conductivity of above 25000-45000 S/cm. The yield of graphene in this example is above 99.9%.

Example 8

(31) This example differs from Example 7 in that the catalyst described in step 1 is K.sub.4[Fe(CN).sub.6].

(32) The transmission electron micrograph of the graphene prepared in the present Example 8 is similar to that of Example 12, as shown in FIG. 2. The Raman spectrum of the graphene prepared in the present Example 8 is similar to that of the graphene prepared in Example 12, as shown in FIG. 3.

(33) Graphene prepared by the present example has a uniform size, a single layer or multi-layer two-dimensional layered structure, a size of 0.5-2 m, and a conductivity of above 25000-45000 S/cm. The yield of graphene in this example is above 99.9%.

Example 9

(34) This example differs from Example 8 in that the catalyst described in step 1 is FeCl.sub.2.

(35) The transmission electron micrograph of the graphene prepared in the present Example 9 is similar to that of Example 12, as shown in FIG. 2. The Raman spectrum of the graphene prepared in the present Example 9 is similar to that of the graphene prepared in Example 12, as shown in FIG. 3.

(36) Graphene prepared by the present example has a uniform size, a single layer or multi-layer two-dimensional layered structure, a size of 0.5-2 m, and a conductivity of above 25000-45000 S/cm. The yield of graphene in this example is above 99.9%.

Example 10

(37) This example differs from Example 9 in that the deoxidation at a high temperature in step 2 is conducted at a temperature of 160 C. for 9 h.

(38) The transmission electron micrograph of the graphene prepared in the present Example 10 is similar to that of Example 12, as shown in FIG. 2. The Raman spectrum of the graphene prepared in the present Example 10 is similar to that of the graphene prepared in Example 12, as shown in FIG. 3.

(39) Graphene prepared by the present example has a uniform size, a single layer or multi-layer two-dimensional layered structure, a size of 0.5-2 m, and a conductivity of above 25000-45000 S/cm. The yield of graphene in this example is above 99.9%.

Example 11

(40) This example differs from Example 10 in that the deoxidation at a high temperature in step 2 is conducted at a microwave strength of 6 kW and a temperature of 135 C. for 0.5 h.

(41) The transmission electron micrograph of the graphene prepared in the present Example 11 is similar to that of Example 12, as shown in FIG. 2. The Raman spectrum of the graphene prepared in the present Example 11 is similar to that of the graphene prepared in Example 12, as shown in FIG. 3.

(42) Graphene prepared by the present example has a uniform size, a single layer or multi-layer two-dimensional layered structure, a size of 0.5-2 m, and a conductivity of above 25000-45000 S/cm. The yield of graphene in this example is above 99.9%.

Example 12

(43) The present example for preparing biomass graphene using cellulose as a raw material is carried out by the following steps:

(44) Step 1: Preparation of a catalyst solution: 8 g of K.sub.3[Fe(CN).sub.6] catalyst is added to 125 g of distilled water and the mixture is stirred for 15 min to obtain a homogeneous catalyst solution;

(45) Step 2: Preparation of a precursor: 17 g of cellulose extracted from sorghum stalks is added to the catalyst solution obtained in step 1, and the mixture is stirred for 3 h and then deoxidated at a microwave strength of 6 kW and a temperature of 140 C., and then dried to obtain a precursor;

(46) Step 3: Heat treatment: To pre-carbonize, the precursor obtained in step 2 is heated to 350 C. at a heating rate of 12 C./min in a nitrogen gas atmosphere to be pre-carbonized for 2 h; For secondary carbonization, the pre-carbonized product is heated to 1050 C. at a heating rate of 6 C./min for heat treatment for 5 h;

(47) Step 4: Acid treatment, water-washing and drying: the product obtained in step 3 is treated with nitric acid, centrifuged and then washed with distilled water to neutral, and then dried at 90 C. to obtain graphene.

(48) FIG. 2 is a transmission electron micrograph of graphene prepared according to Example 12. It can be seen from the figure that the prepared product has a microstructure of two-dimensional layered shape and a size of about 700 nm. FIG. 3 is a Raman spectrum of graphene prepared according to Example 12, in which the G peak is higher than the D peak, the intensity ratio of the two peaks IG/ID=6.4, and a sharp 2D peak appears simultaneously, which further confirms the formation of graphene structure. The conductivity of the product is 32700 S/m, indicating that the graphene prepared by this method has good conductivity.

(49) As can be seen from the above examples, cellulose extracted from biomass from a wide range of sources can be utilized inexpensively as a carbon source to produce graphene, and thus reduces production cost while increasing production. The yield of graphene is above 99%. Graphene with different properties can be obtained by changing the types of cellulose and catalyst and reaction conditions. Graphene prepared by the method of the present disclosure has a uniform size, a single layer or multi-layer two-dimensional layered structure, a size of 0.5-2 m, and a conductivity of 25000-45000 S/m, and can be used in a wider applications; it can be applied to fuel cell, oversized capacitors, fuel cells and other fields, and can also be used as additives for resin, rubber and others. In the present disclosure, the raw materials used are green and non-toxic, the reaction condition is mild, the production safety is high, and the industrial production is easy to be realized.

(50) Although some examples of the present disclosure have been presented herein, it will be understood by those skilled in the art that changes may be made in these examples without departing from the spirit of the disclosure. The above examples are illustrative only and should not be construed as limiting the claimed scope of the present disclosure.