Preparation method and application of sugarcane leaf-based biochar with heat and mass combined storage characteristic

Abstract

The invention discloses a preparation method of sugarcane leaf-based biochar with a heat and mass combined storage characteristic. The method comprises the following steps: (1) putting sugarcane leaf powder into a sulfuric acid solution, stirring, pickling, and carrying out suction filtration until the solution is neutral; (2) stirring the pickled sugarcane leaves with a mixture of a high-performance activator and an inert metal salt aqueous solution to obtain loaded sugarcane leaf powder, and then drying the loaded sugarcane leaf powder to remove residual moisture; (3) carrying out second-stage activation on the dried sugarcane leaf powder in a protective atmosphere; and (4) putting the secondarily activated charcoal powder into a sulfuric acid solution, stirring, carrying out suction filtration by using deionized water until the solution is neutral, and drying, so as to obtain the charcoal material with a tandem mesoporous-microporous pore structure with low-defect site compact carbon layer arrangement. According to the invention, an in-plane-out-of-plane composite thermal conductivity mode based on a biochar material is constructed, and heat and mass combined storage of a low-pressure storage part of the novel adsorption and compression carbon dioxide supercritical / transcritical energy storage system is realized.

Description

Technical Field

[0001] The present invention belongs to energy storage and adsorption materials, and relates to a preparation method of biochar, in particular to a preparation method and application of sugarcane leaf-based biochar with characteristics of combined heat and mass storage. Background Art

[0002] With the continuous increase in the installed capacity ratio of wind power and solar energy, the supporting role of large-scale long-term energy storage technology in the safe and stable operation of the power system has become increasingly prominent.

[0003] Compressed gas energy storage has become one of the key technologies to support the large-scale development of renewable energy in China and ensure energy security.

[0004] Compared with traditional compressed gas energy storage technology, the new adsorption compression carbon dioxide super / critical energy storage system has many advantages such as large energy storage density, low economic cost, long operation life, and negative carbon emissions.

[0005] Biochar is regarded as one of the most promising solid CO2 adsorbents due to its wide sources, low cost, high stability, easy regeneration, adjustable pore structure, etc. However, due to the large randomness of the pore structure distribution of biochar, high defect sites and space thermal resistance, it limits the combined heat and mass storage of CO2 by biochar, reduces the cycle efficiency and response time of the new adsorption compression carbon dioxide super / critical energy storage system. Summary of the Invention

[0006] In order to solve the problems of high-capacity storage - rapid response - adsorption heat recovery and reuse of normal-pressure CO2 in the new adsorption compression carbon dioxide super / critical energy storage system, the present invention provides a preparation method and application of sugarcane leaf-based biochar with characteristics of combined heat and mass storage. By systematically analyzing the influence of different carbon sheet layer combinations on the composite thermal conductivity, deeply analyzing the directional step-by-step etching of the pore structure by pyrolysis gas synergistic activator, reasonably regulating the distribution ratio of phonon scattering sites and the gap between layers, and constructing an "in-plane - out-of-plane" synergistic composite thermal conductivity system, the goal of "high-capacity adsorption - rapid adsorption / desorption" coupling "waste heat storage and reuse" of normal-temperature and normal-pressure CO2 is achieved, fundamentally solving the core problem in the new adsorption compression carbon dioxide super / critical energy storage system - high-capacity storage - rapid response - adsorption heat recovery and reuse of normal-pressure CO2.

[0007] The object of the present invention is achieved by the following technical solutions:

[0008] A preparation method of sugarcane leaf-based biochar with characteristics of combined heat and mass storage, comprising the following steps:

[0009] Step (1): Place the sugarcane leaf powder in a sulfuric acid solution, stir, perform pickling, and filter by suction until neutral. Among them: the concentration of the sulfuric acid solution is 0.1 - 0.5 mol / L, and the solid-liquid ratio is 1:5 - 15;

[0010] Step (2): Stir the pickled sugarcane leaves obtained in step (1) with a mixture of a high-performance activator and an inert metal salt aqueous solution to obtain the loaded sugarcane leaf powder, and then dry it to remove the remaining moisture. Among them: the mass ratio of the pickled sugarcane leaves to the high-performance activator is 1:0.5 - 3, and the mass ratio of the high-performance activator to the auxiliary activator is 1:1 - 3; the high-performance activator is one of KOH, K2CO3, and ZnCl2; the inert metal salt is one of KCl, NaCl, and CuCl2; the drying time is 8 - 14 h;

[0011] Step (3): Perform two-stage activation on the dried sugarcane leaf powder obtained in step (2) under a protective atmosphere. Among them: the temperature of the first-stage activation is 300 - 500 °C to preliminarily carbonize and construct a pyrolysis gas release path, the temperature of the second-stage activation is 700 - 900 °C to sufficiently reduce the content of defect sites in the carbon material, the flow rate of the protective atmosphere is 0.5 - 3 L / min, the heating rate is 5 - 10 °C / min, and the insulation time for both stages of activation is 1 - 2 h. The protective atmosphere is one of nitrogen, argon, carbon dioxide, and water vapor;

[0012] Step (4): Place the biochar powder after secondary activation in step (3) in a sulfuric acid solution, stir, and filter by suction with deionized water until neutral, and then dry to obtain a biochar material with a tandem "meso-micro" pore structure with a dense carbon layer arrangement with low defect sites. Among them: the solid-liquid ratio is 1:5 - 15, the concentration of the sulfuric acid solution is 0.1 - 0.5 mol / L, and the drying time is 8 - 14 h.

[0013] The biochar with a tandem "meso-micro" pore structure with a dense carbon layer arrangement with low defect sites constructed by the above method can be used as an adsorption and adsorption heat reuse material for the internal of the low-pressure storage CO2 equipment of a new adsorption compression carbon dioxide super / critical energy storage system.

[0014] Compared with the prior art, the present invention has the following advantages:

[0015] (1) The present invention uses a multi-metal molten salt coupled with a high-performance activator to achieve the directional layer-by-layer and step-by-step etching of biochar by the high-performance activator-pyrolysis gas, and realizes the construction of a tandem "meso-micro" pore structure with "in-plane-out-of-plane" composite thermal conductivity.

[0016] (2) The present invention adopts a two-stage activation mode. The first-stage activation constructs a pyrolysis gas path, and effectively reduces the broadening effect of pyrolysis gas blockage on the carbon sheet layer spacing during the high-temperature deep activation process.

[0017] (3) The present invention has developed a biochar material with a tandem "meso-micro" pore structure having a dense carbon layer arrangement with low defect sites, constructed a "in-plane - out-of-plane" composite thermal conductivity mode based on the biochar material, and realized the thermal and mass co-storage in the low-pressure storage part of a novel adsorption compression carbon dioxide super / transcritical energy storage system. Description of the Drawings

[0018] Figure 1 Schematic diagram of a tandem "meso-micro" pore with "in-plane - out-of-plane" composite thermal conductivity. Detailed Embodiments

[0019] The technical solutions of the present invention will be further described below in conjunction with embodiments, but are not limited thereto. Any modification or equivalent replacement of the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention shall be covered within the protection scope of the present invention.

[0020] Example 1:

[0021] 3.0 g of pickled sugarcane leaves, 1.0 g of K2CO3, and 2.0 g of CuCl2 were added to 80 ml of an aqueous solution. The resulting mixture was magnetically stirred at 50 °C for 6 h to obtain a uniform viscous solution, which was then transferred to a forced-air drying oven and dried at 105 °C for 12 h. Then, the sugarcane leaf powder was transferred to a horizontal tube furnace. Under a nitrogen atmosphere, it was heated to 400 °C at a heating rate of 5 °C / min, held for 1 h, and then heated to 750 °C at a heating rate of 5 °C / min and held for 1 h. When it cooled to room temperature, the black powder was taken out. After mixing it with an excessive amount of sulfuric acid solution and placing it in a water bath for magnetic stirring at room temperature for 12 h to wash away the residual alkali and salts, after suction filtration to neutrality, the obtained carbon powder was placed in a forced-air drying oven and dried at 105 °C for 12 h to obtain dry carbon powder.

[0022] Example 2:

[0023] 3.0 g of pickled sugarcane leaves, 2.0 g of ZnCl2, and 2.0 g of KCl were added to 80 ml of an aqueous solution. The resulting mixture was magnetically stirred at 60 °C for 6 h to obtain a uniform viscous solution, which was then transferred to a forced-air drying oven and dried at 105 °C for 12 h. Then, the sugarcane leaf powder was transferred to a horizontal tube furnace. Under an argon atmosphere, it was heated to 350 °C at a heating rate of 5 °C / min, held for 1 h, and then heated to 800 °C at a heating rate of 5 °C / min and held for 1 h. When it cooled to room temperature, the black powder was taken out. After mixing it with an excessive amount of sulfuric acid solution and placing it in a water bath for magnetic stirring at room temperature for 12 h to wash away the residual alkali and salts, after suction filtration to neutrality, the obtained carbon powder was placed in a forced-air drying oven and dried at 105 °C for 12 h to obtain dry carbon powder.

[0024] Example 3:

[0025] Add 3.0 g of pickled sugarcane leaves, 2.0 g of KOH, and 2.0 g of KCl to 80 ml of aqueous solution. Magnetically stir the resulting mixture at 60 °C for 6 h to obtain a uniform viscous solution, and then transfer it to a forced-air drying oven to dry at 105 °C for 12 h. Then transfer the sugarcane leaf powder to a horizontal tube furnace, heat it to 350 °C at a heating rate of 5 °C / min under a nitrogen atmosphere, hold for 1 h, and then heat it to 700 °C at a heating rate of 5 °C / min and hold for 1 h. When it cools to room temperature, take out the black powder, mix it with an excessive amount of sulfuric acid solution, place it in a water bath, and magnetically stir it at room temperature for 12 h to wash away the residual alkali and salt. After suction filtration until neutral, place the obtained carbon powder in a forced-air drying oven and dry it at 105 °C for 12 h to obtain dry carbon powder.

Claims

1. A preparation method of sugarcane leaf-based biochar with characteristics of combined heat and mass storage, characterized in that The method includes the following steps: Step (1): Place the sugarcane leaf powder in a sulfuric acid solution, stir, carry out pickling, and filter by suction until neutral; Step (2): Stir the pickled sugarcane leaves obtained in step (1) with a mixture of a high-performance activator and an inert metal salt aqueous solution to obtain the loaded sugarcane leaf powder, and then dry it to remove the remaining moisture; Step (3): Carry out two-stage activation on the dried sugarcane leaf powder obtained in step (2) under a protective atmosphere; Step (4): Place the biochar powder after secondary activation in step (3) in a sulfuric acid solution, stir, filter by suction with deionized water until neutral, and dry to obtain a biochar material with a tandem "meso-micro" pore structure with a dense carbon layer arrangement at low defect sites.

2. The preparation method of sugarcane leaf-based biochar with thermo-mass combined storage characteristics according to claim 1, characterized in that In step (1), the concentration of the sulfuric acid solution is 0.1 - 0.5 mol / L, and the solid-liquid ratio is 1:5 - 15.

3. The preparation method of the sugarcane leaf-based biochar with the characteristics of combined heat and mass storage according to claim 1, characterized in that In step (2), the mass ratio of the pickled sugarcane leaves to the high-performance activator is 1:0.5 - 3, and the mass ratio of the high-performance activator to the auxiliary activator is 1:1 - 3.

4. The preparation method of sugarcane leaf-based biochar with the characteristics of combined heat and mass storage according to claim 1 or 3, characterized in that The high-performance activator is one of KOH, K2CO3, and ZnCl2; the inert metal salt is one of KCl, NaCl, and CuCl2.

5. The preparation method of sugarcane leaf-based biochar with thermo-mass combined storage characteristics according to claim 1, characterized in that In step (2), the drying time is 8 - 14 h.

6. The preparation method of the sugarcane leaf-based biochar with the characteristics of combined heat and mass storage according to claim 1, characterized in that In step (3), the temperature of the first-stage activation is 300 - 500 °C, the temperature of the second-stage activation is 700 - 900 °C, the heating rate is 5 - 10 °C / min, and the holding time for both stages of activation is 1 - 2 h.

7. The preparation method of sugarcane leaf-based biochar with the characteristics of combined heat and mass storage according to claim 1, characterized in that In step (3), the flow rate of the protective atmosphere is 0.5 - 3 L / min, and the protective atmosphere is one of nitrogen, argon, carbon dioxide, and water vapor.

8. The preparation method of sugarcane leaf-based biochar with the characteristics of combined heat and mass storage according to claim 1, characterized in that In step (4), the solid-liquid ratio is 1:5 - 15, and the concentration of the sulfuric acid solution is 0.1 - 0.5 mol / L.

9. The preparation method of the sugarcane leaf-based biochar with the characteristics of combined heat and mass storage according to claim 1, characterized in that In step (4), the drying time is 8 - 14 h.

10. Application of a biochar with a tandem "meso-micro" pore structure with a dense carbon layer arrangement at low defect sites constructed by the method according to any one of claims 1 - 9 as an adsorption and adsorption heat reuse material inside a low-pressure CO2 storage device in an adsorption compression carbon dioxide super / critical energy storage system.

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