Preparation method of lignocellulose-based biomass-derived oxygen-containing functionalized carbon material with adjustable work function

Abstract

The invention discloses a preparation method of a lignocellulose-based biomass-derived oxygen-containing functionalized carbon material with an adjustable work function, and belongs to the technical field of carbon materials. Washing and drying the lignocellulose biomass, mixing the lignocellulose biomass with the hydrogen-rich plastic, pouring the mixture into a crusher, and crushing to prepare powder, so as to obtain mixed powder; the mixed powder is moved into a tubular furnace and then subjected to low-temperature pre-carbonization under inert atmosphere protection, and a low-temperature pre-carbonized solid is obtained; mixing the obtained low-temperature pre-carbonized solid with an activating agent, grinding, transferring into a tubular furnace, carrying out high-temperature carbonization under the protection of an inert atmosphere, cooling, collecting the solid, grinding, crushing, and repeatedly washing with 1-3M diluted hydrochloric acid and ultrapure water, so as to obtain the low-temperature carbonized carbon. And drying to obtain the carbon material, namely the lignocellulose-based biomass derived oxygen-containing functionalized carbon material with the adjustable work function. The lignocellulose-based biomass derived oxygen-containing functionalized carbon material with an adjustable work function can be obtained.

Description

Technical Field

[0001] This invention relates to a method for preparing lignocellulose-based biomass-derived oxygen-functionalized carbon materials with adjustable work function, belonging to the field of carbon materials technology. Background Technology

[0002] Lignocellulose-based biomass possesses a natural aromatic structure and abundant oxygen components, making it a natural material for designing and constructing oxygen-modified functionalized carbon materials (traditional methods, such as concentrated sulfuric acid / nitric acid oxidation, generate waste liquid and pose pollution risks; or oxygen plasma etching, are energy-intensive). Although the carbonization process of lignocellulose-based biomass can retain a certain amount of oxygen components, these components are lost as the temperature increases. Furthermore, the addition of activators (KOH, ZnCl2, etc.) during activation causes a significant loss of oxygen components. Moreover, these traditional direct pyrolysis or activation methods are difficult to adjust the oxygen content on the surface of the derived carbon material; the amount of oxygen retained depends entirely on the temperature and the amount of activator added. Summary of the Invention

[0003] Purpose of the invention: This invention provides a method for preparing lignocellulose-based biomass-derived oxygen-containing functionalized carbon materials with adjustable work function.

[0004] Technical solution: To achieve the above objectives, the technical solution adopted by this invention is as follows: A method for preparing a lignocellulose-based biomass-derived oxygen-containing functionalized carbon material with adjustable work function includes the following steps: Step 1: After washing and drying the lignocellulose biomass, mix it with hydrogen-rich plastic and pour it into a crusher for crushing and grinding to obtain mixed powder.

[0005] Step 2: After the mixed powder is transferred into a tube furnace, it is pre-carbonized at low temperature under an inert atmosphere to obtain a pre-carbonized solid.

[0006] Step 3: The obtained low-temperature pre-carbonized solid is mixed with an activator and then ground. It is then transferred to a tube furnace and carbonized at high temperature under an inert atmosphere. After cooling, the solid is collected, ground and pulverized, and repeatedly washed with 1-3M dilute hydrochloric acid and ultrapure water. After drying, the carbon material obtained is the work function-tunable lignocellulose-based biomass-derived oxygen-containing functionalized carbon material.

[0007] Preferably, the lignocellulose biomass in step 1 is one or a mixture of several of ginkgo leaves, corn stalks, and sugarcane bagasse.

[0008] Preferably, the hydrogen-rich plastic in step 1 is one or a mixture of two of polyethylene (PE) and polypropylene (PP).

[0009] Preferably, the particle size of the mixed powder obtained in step 1 is 200-400 mesh.

[0010] Preferably, the mass ratio of lignocellulose-based biomass to hydrogen-rich plastic in step 1 is 1:10 to 10:1.

[0011] Preferably, the low-temperature pre-carbonization temperature in step 2 is 200–450°C. o C.

[0012] Preferably, the activator in step 3 is one or a mixture of several of KOH, ZnCl2, and MgCl2.

[0013] Preferably, in step 3, the mass ratio of the low-temperature pre-carbonized solid to the activator is 1:5 to 5:1, and the grinding time is 30 to 60 min.

[0014] Preferably, the high-temperature carbonization temperature in step 3 is 600–1000 °C. o C.

[0015] Preferably, the inert atmosphere during carbonization in steps 2 and 3 is N2 or Ar.

[0016] Compared with the prior art, the present invention has the following advantages: This invention incorporates PE / PP, which, during pyrolysis, forms a waxy deposit at low temperatures that encapsulates the lignocellulose-based biomass raw material, preventing oxygen loss due to high temperatures and activators. As the temperature rises, the plastic pyrolyzes to create a localized hydrogen-rich atmosphere. Through a synergistic effect, this regulates the types and content of oxygen components on the surface of the char material, thereby achieving the goal of adjusting the work function of the lignocellulose-based biomass char material. Attached Figure Description

[0017] Figure 1 UPS test spectra of sodium lignosulfonate-derived carbon materials obtained with different PE addition amounts, where BindingEnergy (eV) represents binding energy (unit: eV) and Intensity (au) represents strength (unit: au). Figure 1 Figure (a) shows the UPS test spectrum when the mass ratio of sodium lignosulfonate to plastic is 1:0. Figure 1 Figure (b) shows the UPS test spectrum when the mass ratio of sodium lignosulfonate to plastic is 5:1. Figure 1 Figure (c) shows the UPS test spectrum when the mass ratio of sodium lignosulfonate to plastic is 3:1. Figure 1 Figure (d) shows the UPS test spectrum when the mass ratio of sodium lignosulfonate to plastic is 1:1. Detailed Implementation

[0018] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the invention. After reading the present invention, any modifications of the present invention in various equivalent forms by those skilled in the art will fall within the scope defined by the appended claims.

[0019] Example 1 This embodiment provides a method for preparing lignocellulose-based biomass-derived oxygen-containing functionalized carbon materials with adjustable work function, including the following steps: Step 1: After repeatedly washing and drying the lignocellulose biomass (sodium lignosulfonate), mix it with hydrogen-rich plastic (polyethylene PE). The mass ratio of lignocellulose-based biomass to hydrogen-rich plastic is 1:10. Pour the mixture into a crusher for crushing and grinding to obtain a mixed powder with a particle size of 200-400 mesh.

[0020] Step 2: After transferring the mixed powder into a tube furnace, it undergoes low-temperature pre-carbonization under an inert atmosphere. The low-temperature pre-carbonization temperature is 200°C. o C, the inert atmosphere during carbonization is N2, to obtain a low-temperature pre-carbonized solid.

[0021] Step 3: The obtained low-temperature pre-carbonized solid is mixed with the activator KOH and then ground. The mass ratio of the low-temperature pre-carbonized solid to the activator is 5:1, and the grinding time is 30 minutes. Then, it is transferred to a tube furnace for high-temperature carbonization under an inert atmosphere (N2) at a temperature of 600°C. o C. After cooling, the solid is collected, ground and pulverized, and repeatedly washed with 1M dilute hydrochloric acid and ultrapure water. After drying, the carbon material obtained is the lignocellulose-based biomass-derived oxygen-containing functionalized carbon material with adjustable work function.

[0022] Example 1 This embodiment provides a method for preparing lignocellulose-based biomass-derived oxygen-containing functionalized carbon materials with adjustable work function, including the following steps: Step 1: After repeatedly washing and drying the lignocellulosic biomass (bagasse), mix it with hydrogen-rich plastic (polyethylene PE). The mass ratio of lignocellulosic biomass to hydrogen-rich plastic is 1:10. Pour the mixture into a crusher for crushing and grinding to obtain a mixed powder with a particle size of 200-400 mesh.

[0023] Step 2: After transferring the mixed powder into a tube furnace, it undergoes low-temperature pre-carbonization under an inert atmosphere. The low-temperature pre-carbonization temperature is 200°C. o C, the inert atmosphere during carbonization is N2, to obtain a low-temperature pre-carbonized solid.

[0024] Step 3: The obtained low-temperature pre-carbonized solid is mixed with the activator KOH and then ground. The mass ratio of the low-temperature pre-carbonized solid to the activator is 5:1, and the grinding time is 30 minutes. Then, it is transferred to a tube furnace for high-temperature carbonization under an inert atmosphere (N2) at a temperature of 600°C. o C. After cooling, the solid is collected, ground and pulverized, and repeatedly washed with 1M dilute hydrochloric acid and ultrapure water. After drying, the carbon material obtained is the lignocellulose-based biomass-derived oxygen-containing functionalized carbon material with adjustable work function.

[0025] Example 1 This embodiment provides a method for preparing lignocellulose-based biomass-derived oxygen-containing functionalized carbon materials with adjustable work function, including the following steps: Step 1: After repeatedly washing and drying the lignocellulosic biomass (bagasse), mix it with hydrogen-rich plastic (polyethylene PE). The mass ratio of lignocellulosic biomass to hydrogen-rich plastic is 1:10. Pour the mixture into a crusher for crushing and grinding to obtain a mixed powder with a particle size of 200-400 mesh.

[0026] Step 2: After transferring the mixed powder into a tube furnace, it undergoes low-temperature pre-carbonization under an inert atmosphere. The low-temperature pre-carbonization temperature is 200°C. o C, the inert atmosphere during carbonization is N2, to obtain a low-temperature pre-carbonized solid.

[0027] Step 3: The obtained low-temperature pre-carbonized solid is mixed with the activator KOH and then ground. The mass ratio of the low-temperature pre-carbonized solid to the activator is 5:1, and the grinding time is 30 minutes. Then, it is transferred to a tube furnace for high-temperature carbonization under an inert atmosphere (N2) at a temperature of 600°C. o C. After cooling, the solid is collected, ground and pulverized, and repeatedly washed with 1M dilute hydrochloric acid and ultrapure water. After drying, the carbon material obtained is the lignocellulose-based biomass-derived oxygen-containing functionalized carbon material with adjustable work function.

[0028] Example 2 This embodiment provides a method for preparing lignocellulose-based biomass-derived oxygen-containing functionalized carbon materials with adjustable work function, including the following steps: Step 1: After repeatedly washing and drying the lignocellulosic biomass (bagasse), mix it with hydrogen-rich plastic (polyethylene PE). The mass ratio of lignocellulosic biomass to hydrogen-rich plastic is 10:1. Pour the mixture into a crusher for crushing and grinding to obtain a mixed powder with a particle size of 200-400 mesh.

[0029] Step 2: After transferring the mixed powder into a tube furnace, it undergoes low-temperature pre-carbonization under an inert atmosphere. The low-temperature pre-carbonization temperature is 450°C.o C, with Ar as the inert atmosphere during carbonization, yields a low-temperature pre-carbonized solid.

[0030] Step 3: The obtained low-temperature pre-carbonized solid is mixed with the activator ZnCl2 and then ground. The mass ratio of the low-temperature pre-carbonized solid to the activator is 1:5, and the grinding time is 60 minutes. Then, it is transferred to a tube furnace for high-temperature carbonization under an inert atmosphere (N2) at a temperature of 1000°C. o C. After cooling, the solid is collected, ground and pulverized, and repeatedly washed with 3M dilute hydrochloric acid and ultrapure water. After drying, the carbon material obtained is the lignocellulose-based biomass-derived oxygen-containing functionalized carbon material with adjustable work function.

[0031] Example 3 This embodiment provides a method for preparing lignocellulose-based biomass-derived oxygen-containing functionalized carbon materials with adjustable work function, including the following steps: Step 1: After repeatedly washing and drying the lignocellulosic biomass (corn stalks), mix it with hydrogen-rich plastic (polypropylene PP). The mass ratio of lignocellulosic biomass to hydrogen-rich plastic is 5:1. Pour the mixture into a crusher for crushing and grinding to obtain a mixed powder with a particle size of 200-400 mesh.

[0032] Step 2: After transferring the mixed powder into a tube furnace, it undergoes low-temperature pre-carbonization under an inert atmosphere. The low-temperature pre-carbonization temperature is 300°C. o C, the inert atmosphere during carbonization is N2, to obtain a low-temperature pre-carbonized solid.

[0033] Step 3: The obtained low-temperature pre-carbonized solid is mixed with the activator ZnCl2 and then ground. The mass ratio of the low-temperature pre-carbonized solid to the activator is 3:1, and the grinding time is 40 minutes. Then, it is transferred to a tube furnace for high-temperature carbonization under an inert atmosphere (Ar) at a temperature of 800°C. o C. After cooling, the solid is collected, ground and pulverized, and repeatedly washed with 2M dilute hydrochloric acid and ultrapure water. After drying, the carbon material obtained is the lignocellulose-based biomass-derived oxygen-containing functionalized carbon material with adjustable work function.

[0034] Example 4 This embodiment provides a method for preparing lignocellulose-based biomass-derived oxygen-containing functionalized carbon materials with adjustable work function, including the following steps: Step 1: The lignocellulose biomass (a mixture of ginkgo leaves, corn stalks, and sugarcane bagasse), in one embodiment, a mixture of ginkgo leaves and corn stalks, a mixture of corn stalks and sugarcane bagasse, and a mixture of ginkgo leaves and sugarcane bagasse, is repeatedly washed and dried, then mixed with hydrogen-rich plastic. The hydrogen-rich plastic is a mixture of polyethylene (PE) and polypropylene (PP), with a mass ratio of lignocellulose-based biomass to hydrogen-rich plastic of 5:1. The mixture is then fed into a crusher for crushing and grinding to obtain a mixed powder with a particle size of 200-400 mesh.

[0035] Step 2: After transferring the mixed powder into a tube furnace, it undergoes low-temperature pre-carbonization under an inert atmosphere. The low-temperature pre-carbonization temperature is 300°C. o C, the inert atmosphere during carbonization is N2, to obtain a low-temperature pre-carbonized solid.

[0036] Step 3: The obtained low-temperature pre-carbonized solid is mixed with an activator and then ground. The activator is a mixture of KOH, ZnCl2, and MgCl2. In another embodiment, the activator is a mixture of ZnCl2 and MgCl2. In yet another embodiment, the activator is a mixture of KOH and MgCl2. In yet another embodiment, the activator is a mixture of KOH and ZnCl2. The mass ratio of the low-temperature pre-carbonized solid to the activator is 3:1, and the grinding time is 40 minutes. Then, it is transferred to a tube furnace for high-temperature carbonization under an inert atmosphere. The inert atmosphere during carbonization is Ar, and the high-temperature carbonization temperature is 800°C. o C. After cooling, the solid is collected, ground and pulverized, and repeatedly washed with 2M dilute hydrochloric acid and ultrapure water. After drying, the carbon material obtained is the lignocellulose-based biomass-derived oxygen-containing functionalized carbon material with adjustable work function.

[0037] like Figure 1 As shown, the work function is calculated as follows:

[0038] in, Represents the work function. hv The photoelectron energy of the helium lamp ultraviolet light is 21.22 eV. This indicates the secondary electron cutoff edge.

[0039] Table 1. Work function values ​​of sodium lignosulfonate-derived carbon materials obtained with different PE addition amounts.

[0040] Methods for preparing carbon materials by blending biomass with polyethylene (PE) or polypropylene (PP) and then pyrolyzing them have been established. Research in these methods typically focuses on improving the physical and structural properties of the carbon materials, such as specific surface area, pore structure, and carbon yield. The blended plastics are often considered as hydrogen sources or pyrolysis reaction modulators, with less attention paid to the regulation of oxygen-containing functional groups and their electronic properties on the carbon material surface. During the aforementioned blending pyrolysis process, PE or PP easily forms a deposited carbon layer on the carbon material surface after high-temperature pyrolysis. This deposited layer can alter the surface chemical environment of the carbon material to some extent. However, when the coating effect is too strong, it may lead to the shielding or solidification of oxygen-containing functional groups on the pyrolyzed carbon surface, which is detrimental to further regulation of the electronic properties of the carbon material surface, especially the work function.

[0041] This invention introduces a staged pyrolysis process and a synergistic KOH activation process into a biomass-PE / PP blend system, allowing each component to exert differentiated effects within different temperature ranges. In the low-temperature pre-carbonization stage, PE / PP easily forms a molten state, providing physical coating and slow-release protection to the surface of the biomass pyrolysis char, thereby inhibiting the disorderly loss of oxygen-containing components. In the heating and high-temperature stages, the hydrogen-rich atmosphere generated by PE / PP pyrolysis alters the reaction microenvironment in the traditional activation process, while the chemical etching effect of KOH on the carbon material at high temperatures can regulate and partially remove the deposited char layer formed by PE pyrolysis, allowing the char material surface to be re-exposed and participate in the reaction. Through the synergistic effect of PE pyrolysis and KOH activation etching, excessive coating of oxygen-containing functional groups by the deposited char is avoided, while the regulatory effect of the hydrogen-rich atmosphere on the evolution path of oxygen-containing functional groups is preserved. This allows for the staged and controllable regulation of the type, distribution, and stability of oxygen-containing functional groups on the char material surface. Figure 1 Table 1 shows that the work function can be flexibly adjusted by controlling the amount of activator, plastic added, and temperature. However, if relying solely on a single variable, especially the activator or temperature, often results in a smaller work function due to more intensive addition and higher temperature, leading to more severe deoxidation of the carbon material. Therefore, the triple synergistic mechanism of low-temperature melting protection, high-temperature hydrogen-rich atmosphere control, and chemical activation etching provides a new technical approach for controlling the electronic structure of biomass-derived carbon materials, thereby achieving an adjustable work function.

[0042] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a lignocellulose-based biomass-derived oxygen-containing functionalized carbon material with adjustable work function, characterized in that, Includes the following steps: Step 1: After washing and drying the lignocellulose biomass, mix it with hydrogen-rich plastic and pour it into a crusher for crushing and grinding to obtain mixed powder; Step 2: After the mixed powder is transferred into a tube furnace, it is pre-carbonized at low temperature under an inert atmosphere to obtain a pre-carbonized solid at low temperature; Step 3: The obtained low-temperature pre-carbonized solid is mixed with an activator and then ground. It is then transferred to a tube furnace and carbonized at high temperature under an inert atmosphere. After cooling, the solid is collected, ground and pulverized, and repeatedly washed with 1-3M dilute hydrochloric acid and ultrapure water. After drying, the carbon material obtained is the work function-tunable lignocellulose-based biomass-derived oxygen-containing functionalized carbon material.

2. The method for preparing the lignocellulose-based biomass-derived oxygen-containing functionalized carbon material with adjustable work function according to claim 1, characterized in that: The lignocellulose biomass in step 1 is one or a mixture of several of the following: ginkgo leaves, corn stalks, and sugarcane bagasse.

3. The method for preparing the lignocellulose-based biomass-derived oxygen-containing functionalized carbon material with adjustable work function according to claim 2, characterized in that: In step 1, the hydrogen-rich plastic is one or a mixture of two of polyethylene (PE) and polypropylene (PP).

4. The method for preparing the lignocellulose-based biomass-derived oxygen-containing functionalized carbon material with adjustable work function according to claim 3, characterized in that: The particle size of the mixed powder obtained in step 1 is 200-400 mesh.

5. The method for preparing the lignocellulose-based biomass-derived oxygen-containing functionalized carbon material with adjustable work function according to claim 4, characterized in that: In step 1, the mass ratio of lignocellulose-based biomass to hydrogen-rich plastic is 1:10 to 10:

1.

6. The method for preparing the lignocellulose-based biomass-derived oxygen-containing functionalized carbon material with adjustable work function according to claim 5, characterized in that: The low-temperature pre-carbonization temperature in step 2 is 200–450°C. o C.

7. The method for preparing the lignocellulose-based biomass-derived oxygen-containing functionalized carbon material with adjustable work function according to claim 6, characterized in that: In step 3, the activator is one or a mixture of several of KOH, ZnCl2, and MgCl2.

8. The method for preparing the lignocellulose-based biomass-derived oxygen-containing functionalized carbon material with adjustable work function according to claim 7, characterized in that: In step 3, the mass ratio of low-temperature pre-carbonized solid to activator is 1:5 to 5:1, and the grinding time is 30 to 60 min.

9. The method for preparing the lignocellulose-based biomass-derived oxygen-containing functionalized carbon material with adjustable work function according to claim 8, characterized in that: The high-temperature carbonization temperature in step 3 is 600–1000 °C. o C.

10. The method for preparing the lignocellulose-based biomass-derived oxygen-containing functionalized carbon material with adjustable work function according to claim 9, characterized in that: The inert atmosphere during carbonization in steps 2 and 3 is N2 or Ar.

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