Bamboo charcoal hydrogen storage material and preparation and application thereof

Abstract

The invention belongs to the field of hydrogen storage materials, and particularly relates to a preparation method of a bamboo charcoal hydrogen storage material, which comprises the following steps: carbonizing a bamboo raw material to obtain a carbonized material, mixing the carbonized material with a modifier, and activating to obtain an activated material; and washing and drying the activated material to obtain the bamboo charcoal hydrogen storage material. Wherein at least one of a bamboo raw material before carbonization, a carbonized material before activation, an activated material after activation and a washing material after washing is subjected to liquid-phase microwave pretreatment in advance before the next operation; the modifier comprises an alkaline component. The invention also comprises the material prepared by the preparation method and application of the material in a hydrogen storage material. Bamboo raw materials which are difficult to treat are successfully utilized for the first time in the industry to prepare the material with good hydrogen storage activity.

Description

Technical Field

[0001] The invention belongs to the field of carbon materials, and in particular relates to the field of bamboo charcoal hydrogen storage materials. Background Art

[0002] At present, the importance of hydrogen energy in the global energy system is becoming increasingly prominent, and related technologies in production, transportation, storage and other links are also in urgent need of development. Among them, the development of efficient, safe and low-cost solid hydrogen storage materials is particularly urgent. In recent years, biomass-based carbon materials have been widely reported in the field of solid hydrogen storage due to their wide sources, simple preparation and rich pore structures, and have gradually shown good development potential.

[0003] Existing carbon hydrogen storage materials mainly include pure carbon-based materials and carbon-based materials loaded with active ingredients, among which the active materials are mainly precious metals and some metal oxides.

[0004] For example, the Chinese patent document with publication number CN110835107A discloses a biomass porous carbon material and its preparation method, which specifically describes the preparation method through the steps of drying, crushing, carbonization, activation, pickling and deep cooling. The Chinese patent document with publication number CN101780952A discloses a preparation method of porous carbon loaded with functional oxides, the steps of which are: selecting biomass materials, carbonizing them under vacuum or inert conditions and in a temperature range of 400 to 1000°C; preparing porous carbon by physical activation or chemical activation process according to the requirements of pore structure; impregnating the obtained porous carbon into the precursor solution of element M, washing it with distilled water several times, and drying it; calcining the obtained porous carbon at 300 to 1000°C under vacuum or inert atmosphere to obtain the loaded functional oxide M. x O y For another example, the Chinese patent document with publication number CN118125374A discloses a hydrogen storage material, which includes 3-5% of a main catalyst, 1-2% of a catalyst promoter and the balance MgH; the main catalyst includes porous carbon and Pt and Pd active components adsorbed on the surface of the porous carbon, and the preparation method of the main catalyst includes the following steps: adding porous carbon powder into an activation solution, stirring and immersing it to obtain a modified porous carbon powder, stirring and mixing the modified porous carbon powder with a mixed solution containing chloroplatinic acid and chloropalladic acid to obtain a mixed dispersion, adding a reducing agent and a stabilizer to the mixed dispersion, stirring and dissolving, and then standing to precipitate, separating and washing the precipitate, and then drying to obtain the main catalyst.

[0005] In summary, although the prior art discloses some biomass carbon-based hydrogen storage materials, biomass-based carbon materials still have problems such as lack of hydrogen storage active sites, weak adsorption force, and lack of precise control of microporous structure. The hydrogen storage capacity is still at a relatively low level. Therefore, there is still a lack of highly specific biomass carbon-based efficient hydrogen storage materials, which limits the development of solid-state hydrogen storage technology. In addition, different biomass has different physical and chemical characteristics, and the prior art does not have a solution for how to use the characteristics of bamboo to prepare bamboo-based materials that meet the requirements of hydrogen storage. Summary of the invention

[0006] In view of the technical problem in the industry that there is a lack of development of hydrogen storage materials that meet the characteristics of bamboo raw materials, the first purpose of the present invention is to provide a method for preparing bamboo charcoal hydrogen storage materials, aiming to utilize the characteristics of bamboo to prepare materials that meet the requirements of hydrogen storage applications.

[0007] The second purpose of the present invention is to provide a bamboo charcoal hydrogen storage material prepared by the preparation method and its application.

[0008] The third object of the present invention is to provide a hydrogen storage device containing the bamboo charcoal hydrogen storage material.

[0009] For gas storage materials, they are different from conventional gas adsorption materials, and the key difficulty lies in how to achieve high-density storage and easy release of gases. In addition, for hydrogen storage, the gas that needs to be confined is hydrogen, which is different from other gases, such as propane, butane, propylene, butene, benzene compounds, etc. Its molecules are small and its weight is light. Storage materials suitable for other gases are difficult to simply transfer to hydrogen systems to achieve similar hydrogen storage effects. Not only that, different biomasses have different physical and chemical characteristics. For example, for bamboo raw materials, its texture is dense, and it is more difficult to construct hydrogen storage materials that are suitable for stable confinement of hydrogen than other biomass. Based on this, bamboo charcoal-based hydrogen storage materials are still a blank in the industry, and there is no technology in the industry on how to overcome the physical and chemical characteristics of bamboo and then construct physical and chemical characteristics suitable for hydrogen storage. In response to this problem, the present invention has been studied in depth and provides the following improvement scheme:

[0010] The preparation method of bamboo charcoal hydrogen storage material comprises the following steps: carbonizing bamboo raw material to obtain carbonized material, mixing the carbonized material with a modifier and activating the mixture to obtain activated material; washing and drying the activated material to obtain the bamboo charcoal hydrogen storage material; wherein at least one of the bamboo raw material before carbonization, the carbonized material before activation, the activated material after activation, and the washed material after washing is pre-treated with liquid phase microwave before the next operation;

[0011] The modifier contains a basic component.

[0012] In view of the difficulty in preparing materials that meet the characteristics of hydrogen storage due to the density of bamboo raw materials, the present invention innovatively adds the liquid phase microwave pretreatment step in the steps of carbonization, before activation and after activation, which unexpectedly helps to adapt to the structural characteristics of bamboo raw materials, and can construct a microstructure that is suitable for hydrogen storage. Not only that, it is also conducive to constructing active sites that are suitable for hydrogen storage on the surface. The present invention is the first in the industry to successfully use bamboo raw materials that are difficult to process to prepare materials with good hydrogen storage activity.

[0013] In the present invention, the bamboo raw material is at least one of bamboo stems and bamboo nodes, and can further be 1.5 to 5 years old bamboo.

[0014] In the present invention, the particle size of the bamboo raw material is 50 to 80 meshes.

[0015] In the present invention, the atmosphere in the carbonization stage is an oxygen-free or low-oxygen atmosphere; for example, it may be at least one of nitrogen and an inert gas.

[0016] In the present invention, the carbonization temperature is 400 to 800°C; further, it can be 500 to 700°C.

[0017] The heating rate in the carbonization stage may be 1 to 10°C / min, and may further be 5 to 8°C / min in consideration of the preparation efficiency.

[0018] In the present invention, the carbonization time is 0.5 to 5 hours, and can further be 1 to 3 hours.

[0019] In the present invention, the modifier includes at least one of potassium hydroxide, sodium hydroxide and zinc chloride.

[0020] Preferably, the weight ratio of the carbonized material to the modifier is 1:1-8, and can further be 1:3-6.

[0021] Preferably, the activation stage is carried out in an oxygen-free or low-oxygen atmosphere.

[0022] Preferably, the temperature in the activation stage is 600-850° C., preferably 650-750° C., and more preferably 690-710° C. The present invention shows that at this preferred temperature, the problem of bamboo raw materials being difficult to prepare for hydrogen storage due to their physical and chemical characteristics can be unexpectedly further solved, and better hydrogen storage performance of bamboo-based materials can be obtained.

[0023] The heating rate in the activation stage is 1 to 10° C. / min, and can be further 2 to 4° C. / min in consideration of the preparation efficiency.

[0024] Preferably, the holding time at the activation temperature is 1 to 5 hours, and further can be 2 to 3 hours.

[0025] In the present invention, the solvent in the liquid phase microwave pretreatment stage is an aqueous solution, preferably distilled water. In the present invention, based on the liquid phase microwave pretreatment, it is different from conventional microwave carbonization and activation, and its role is to adapt to the characteristics of bamboo raw materials and construct its microstructure. Not only that, it also constructs active sites suitable for hydrogen storage and a stable confined porous structure, thereby solving the problem of difficulty in preparing hydrogen storage materials due to the physicochemical characteristics of bamboo raw materials.

[0026] Preferably, the liquid-to-solid ratio in the liquid-phase microwave pretreatment stage is 5 to 20 mL / g; further, it may be 10 to 15 mL / g.

[0027] There is no particular requirement for the power of the microwaves, and for example, it can be 600 to 800W.

[0028] Preferably, the treatment time of the liquid phase microwave pretreatment stage is 2 to 10 minutes, more preferably 4 to 6 minutes.

[0029] In the present invention, the washing includes acid washing and water washing steps.

[0030] The scheme described in the present invention optionally includes the following four implementation schemes: Scheme A: The bamboo raw material is subjected to the liquid-phase microwave pretreatment in advance, and then the subsequent carbonization, activation, washing and drying treatments are carried out to obtain the bamboo charcoal hydrogen storage material. Scheme B: The bamboo raw material is subjected to carbonization treatment, and the carbonized material is subjected to the liquid-phase microwave pretreatment and then activated, washed and dried. Scheme C: The bamboo raw material is subjected to carbonization and activation treatment, and the activated material is subjected to liquid-phase microwave pretreatment and then washed and dried. Scheme D: The bamboo raw material is subjected to liquid-phase microwave pretreatment after carbonization, activation and washing, and then dried.

[0031] The research of the present invention also shows that the process of the preferred scheme A can unexpectedly further solve the preparation problems caused by the physical and chemical characteristics of bamboo raw materials, and can obtain better hydrogen storage performance of bamboo-based materials.

[0032] In the present invention, the washing process includes an acidic process and a water washing process.

[0033] The present invention also provides a bamboo charcoal hydrogen storage material prepared by the preparation method. The preparation method of the present invention can give the prepared material special physical and chemical characteristics, and the material prepared by the preparation method can unexpectedly adapt to the requirements of hydrogen storage applications, and can obtain excellent bamboo-based material hydrogen storage performance.

[0034] The invention also provides an application of the bamboo charcoal hydrogen storage material prepared by the preparation method, which is used as a hydrogen storage material.

[0035] The present invention also provides a hydrogen storage device, which comprises the bamboo charcoal hydrogen storage material prepared by the preparation method, or is prepared from the bamboo charcoal hydrogen storage material.

[0036] The hydrogen storage device of the present invention, in addition to comprising the bamboo charcoal hydrogen storage material of the present invention, may have conventional components and structural features in addition.

[0037] Beneficial Effects

[0038] The present invention innovatively adds the liquid phase microwave pretreatment step to the carbonization, before activation and after activation steps, which unexpectedly helps to adapt to the structural characteristics of bamboo raw materials, can construct a hydrogen storage-adaptive microstructure, and is also conducive to constructing hydrogen storage-adaptive active sites on the surface. The present invention is the first in the industry to successfully use bamboo raw materials that are difficult to process to prepare materials with good hydrogen storage activity.

[0039] The present invention also shows that the use of the preferred scheme A can further achieve process synergy, which helps to further enhance the hydrogen storage performance of the prepared bamboo-based material. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 It is a nitrogen adsorption-desorption curve diagram of the bamboo-based porous carbon prepared in Examples 1 to 3 and 7.

[0041] Figure 2 This is a pore size distribution diagram of the bamboo-based porous carbon prepared in Examples 1 to 3 and 7.

[0042] Figure 3 These are scanning electron microscope images of Examples 1 to 5 and Comparative Example 1, wherein a is Example 1, b is Example 2, c is Example 3, d is Example 4, e is Example 5, and f is Comparative Example 2.

[0043] Figure 4 This is the hydrogen adsorption isotherm of the bamboo-based porous carbon prepared in Example 2 at a temperature of 77K. DETAILED DESCRIPTION

[0044] For a better understanding of the present invention, the following examples are further descriptions of the present invention.

[0045] The present invention provides an optional method for preparing a bamboo-based hydrogen storage material, comprising the following steps:

[0046] (1) Microwave treatment: The bamboo is washed and dried, ground into bamboo powder, mixed with deionized water, and subjected to microwave treatment. The powder is then washed, filtered, and dried for later use;

[0047] (2) pyrolysis carbonization: carbonizing the microwaved bamboo powder obtained in step (1) at high temperature under nitrogen-limited oxygen conditions to obtain bamboo-based porous carbon;

[0048] (3) KOH activation: the bamboo-based porous carbon obtained by pyrolysis carbonization in step (2) is mixed with an alkali activator in a certain proportion, ground and mixed evenly in a mortar, and then activated at high temperature in a nitrogen environment for alkali modification;

[0049] (4) Cleaning and drying: The porous carbon modified in step (3) is first cleaned with an acid solution, then washed with deionized water until neutral, and dried to obtain a bamboo-based porous carbon for hydrogen storage.

[0050] In the present invention, microwaves are carried out in an open container.

[0051] The high-temperature carbonization in step (2) and the high-temperature activation in step (3) are both carried out in a high-temperature tube furnace.

[0052] Preferably, the acid solution in step (4) is 5-15% hydrochloric acid.

[0053] In the present invention, the power of the microwave is, for example, 650-700W.

[0054] In the present invention, the bamboo raw material is two-year-old bamboo (bamboo stem) from Changde City, Hunan Province.

[0055] Example 1

[0056] A method for preparing recyclable bamboo-based porous carbon capable of absorbing hydrogen, comprising the following steps:

[0057] (1) Microwave treatment: The bamboo is washed and dried, ground into bamboo powder, passed through an 80-mesh sieve, and mixed with deionized water at a liquid-to-solid ratio of 10-15 ml / g. After microwave treatment for 5 min, the bamboo is washed, filtered, and dried for later use;

[0058] (2) Pyrolysis carbonization: The microwaved bamboo powder obtained in step (1) is placed in a tubular furnace and subjected to high-temperature carbonization in a nitrogen-limited oxygen environment under the following conditions: a heating rate of 5°C / min, a carbonization temperature of 650°C, and a carbonization time of 1 h, to obtain a bamboo-based porous carbon;

[0059] (3) KOH activation: The bamboo-based porous carbon obtained by pyrolysis carbonization in step (2) is mixed with KOH in a weight ratio of 1:4, ground and mixed evenly in a mortar, and activated at high temperature in a nitrogen environment for alkali modification. The activation conditions are: heating rate 3°C / min, activation temperature 600°C, and activation time 2h; then the temperature is lowered to room temperature and washed with 10% hydrochloric acid solution, then washed with deionized water until neutral, and dried to obtain bamboo-based porous carbon for hydrogen storage.

[0060] Example 2

[0061] Compared with Example 1, the only difference is that the activation temperature in step (3) is 700° C., and the other operations and parameters are the same as in Example 1.

[0062] Example 3

[0063] Compared with Example 1, the only difference is that the activation temperature in step (3) is 800° C., and the other operations and parameters are the same as in Example 1.

[0064] Example 4

[0065] Compared with Example 2, the only difference is that Scheme B performs microwave liquid phase pretreatment on the carbonized material, that is, carbonization is performed in advance, and the carbonized material is subjected to microwave liquid phase pretreatment and then subjected to subsequent activation treatment, and the steps are:

[0066] (1) Pyrolysis carbonization: The bamboo was cleaned and dried, ground into bamboo powder, passed through an 80-mesh sieve, and placed in a tubular furnace for high-temperature carbonization under a nitrogen-limited oxygen environment at a heating rate of 5°C / min, a carbonization temperature of 650°C, and a carbonization time of 1 h to obtain bamboo-based porous carbon;

[0067] (2) Microwave treatment: the bamboo-based porous carbon obtained in step (1) was mixed with deionized water (the amount was the same as in Example 1), and the mixture was treated with microwaves (the microwave power was the same as in Example 1) for 5 min, and then the mixture was washed, filtered, and dried for later use;

[0068] (3) KOH activation: The bamboo-based porous carbon after microwave treatment in step (2) is mixed with KOH in a weight ratio of 1:4, ground and mixed evenly in a mortar, and activated at high temperature in a nitrogen environment for alkali modification. The activation conditions are: heating rate 3°C / min, activation temperature 700°C, and activation time 2h; then cooled to room temperature and washed with 10% hydrochloric acid solution, then washed with deionized water until neutral, and dried to obtain bamboo-based porous carbon for hydrogen storage.

[0069] Example 5

[0070] Compared with Example 2, the only difference is that Scheme D performs microwave liquid phase pretreatment on the activated material, that is, carbonization and activation are performed in advance, and then the activated material is washed and then subjected to microwave liquid phase pretreatment, and the steps are:

[0071] (1) Pyrolysis carbonization: The bamboo was cleaned and dried, ground into bamboo powder, passed through an 80-mesh sieve, and placed in a tubular furnace for high-temperature carbonization under a nitrogen-limited oxygen environment at a heating rate of 5°C / min, a carbonization temperature of 650°C, and a carbonization time of 1 h to obtain bamboo-based porous carbon;

[0072] (2) KOH activation: The bamboo-based porous carbon obtained by carbonization in step (1) was mixed with KOH in a mass ratio of 1:4, ground and mixed evenly in a mortar, and activated at high temperature in a nitrogen environment for alkali modification. The activation conditions were: a heating rate of 3°C / min, an activation temperature of 700°C, an activation time of 2h, and after cooling to room temperature, the mixture was washed with a 10% hydrochloric acid solution, and then washed with deionized water until neutral for use.

[0073] (3) Microwave treatment: The porous carbon obtained in step (2) was mixed with deionized water in a ratio of 1:10, and microwaved for 5 min. The mixture was then washed, filtered, and dried to obtain bamboo-based porous carbon for hydrogen storage.

[0074] Example 6

[0075] Compared with Example 2, the only difference is that the microwave time in step (2) is:

[0076] A: The microwave time is 2 min, and other operations and parameters are the same as in Example 2.

[0077] B: The microwave time is 10 min, and other operations and parameters are the same as those in Example 2.

[0078] Example 7

[0079] Compared with Example 2, the only difference is that the heating rate during the activation process of step (3) is:

[0080] A: The heating rate is 5°C / min, and other operations and parameters are the same as those in Example 2.

[0081] B: The heating rate is 10°C / min, and other operations and parameters are the same as those in Example 2.

[0082] Comparative Example 1

[0083] Compared with Example 1, the only difference is that in step 1, microwave treatment is not performed, and other operations and parameters are the same as in Example 1.

[0084] Comparative Example 2

[0085] Compared with Example 2, the only difference is that in step 1, microwave treatment is not performed, and other operations and parameters are the same as in Example 2.

[0086] Comparative Example 3

[0087] Compared with Example 2, the only difference is that in step 1, liquid phase microwave-assisted treatment is not used, that is, the bamboo powder is directly subjected to microwave treatment under nitrogen, and other operations and parameters are the same as those in Example 2.

[0088] Comparative Example 4

[0089] Compared with Example 2, the only difference is that microwave treatment is not performed in step 1, but microwaves are used as a heating source to assist activation treatment in step 3. Other operations and parameters are the same as in Example 2.

[0090] Table 1 Specific surface area, pore volume, pore size and yield of biochar prepared in Examples 1 to 5, Example 7 and Comparative Examples 1 to 4

[0091]

[0092]

[0093] The typical case biochar was subjected to hydrogen adsorption efficiency experiments, and the hydrogen adsorption capacity at normal pressure was determined as shown in Table 2;

[0094] Table 2 Hydrogen adsorption efficiency

[0095]

[0096] It can be seen from Table 2 that by adopting Scheme A and following the conditions of Example 2, better hydrogen storage performance can be obtained.

Claims

1. A method for preparing a bamboo charcoal hydrogen storage material, comprising: carbonizing a bamboo raw material to obtain a carbonized material, and then mixing the carbonized material with a modifier and activating the mixture to obtain an activated material; washing and drying the activated material to obtain the bamboo charcoal hydrogen storage material; characterized in that: in, At least one of the bamboo raw material before carbonization, the carbonized material before activation, the activated material after activation, and the washed material after washing is pre-treated with liquid phase microwave before the next operation; The modifier contains a basic component.

2. The method for preparing the bamboo charcoal hydrogen storage material according to claim 1, characterized in that: The bamboo raw material is at least one of bamboo stems and bamboo nodes; Preferably, the particle size of the bamboo raw material is 50 to 80 meshes.

3. The method for preparing the bamboo charcoal hydrogen storage material according to claim 1, characterized in that: The atmosphere during the carbonization stage is an oxygen-free or low-oxygen atmosphere; Preferably, the carbonization temperature is 400-800°C; Preferably, the carbonization time is 0.5 to 5 hours.

4. The method for preparing the bamboo charcoal hydrogen storage material according to claim 1, characterized in that: The modifier includes at least one of potassium hydroxide, sodium hydroxide and zinc chloride; Preferably, the weight ratio of the carbonized material to the modifier is 1:1-8.

5. The method for preparing the bamboo charcoal hydrogen storage material according to claim 1, characterized in that: The activation stage is carried out in an oxygen-free or low-oxygen atmosphere; Preferably, the temperature in the activation stage is 600-850°C; preferably 650-750°C, more preferably 690-710°C; Preferably, the holding time at the activation temperature is 1 to 5 hours.

6. The method for preparing the bamboo charcoal hydrogen storage material according to any one of claims 1 to 5, characterized in that: The solvent in the liquid phase microwave pretreatment stage is an aqueous solution, preferably distilled water; Preferably, the liquid-to-solid ratio in the liquid-phase microwave pretreatment stage is 5 to 20 mL / g.

7. The method for preparing the bamboo charcoal hydrogen storage material according to claim 6, characterized in that: The power of microwave is 600-800W; Preferably, the treatment time of the liquid phase microwave pretreatment stage is 2 to 10 minutes; Preferably, the bamboo raw material is subjected to the liquid phase microwave pretreatment in advance, and then subjected to subsequent carbonization, activation, washing and drying treatments to obtain the bamboo charcoal hydrogen storage material; Preferably, the washing process includes an acidic process and a water washing process.

8. A bamboo charcoal hydrogen storage material prepared by the preparation method according to any one of claims 1 to 7.

9. An application of the bamboo charcoal hydrogen storage material prepared by the preparation method according to any one of claims 1 to 7, characterized in that: It is used as a hydrogen storage material.

10. A hydrogen storage device, characterized in that: The invention comprises a bamboo charcoal hydrogen storage material prepared by the preparation method according to any one of claims 1 to 7, or is prepared from the bamboo charcoal hydrogen storage material.

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