CN107403698A - A kind of application that the method for activated carbon and its activated carbon of preparation are prepared using biomass - Google Patents

Abstract

The invention discloses a method for preparing active carbon from biomass and the application of the prepared active carbon. The method is to dry and pulverize the biomass, soak it in a certain concentration of acid solution for 1-2h, then place it in an open hydrothermal system, heat it in a muffle furnace to 180-250°C, and keep it warm for 5-8h to obtain Carbon precursor, after natural cooling, the carbon precursor is washed to neutrality, after suction filtration and drying, mixed with a certain proportion of alkaline activator powder, placed in a protective atmosphere for high-temperature activation, after natural cooling to room temperature, washed to neutrality, Dry and serve. The obtained activated carbon material has uniform particle size and large specific surface area, and the prepared supercapacitor has high specific capacity and good cycle stability. The method uses agricultural waste biomass raw materials to prepare carbon electrode materials for supercapacitors through a simple and rapid method, turns waste into wealth, makes full use of resources, reduces environmental pollution, has good economic benefits, and is beneficial to industrial production.

Description

A method of using biomass to prepare activated carbon and the application of the prepared activated carbon

Technical field:

The invention relates to the technical field of preparation of activated carbon materials, in particular to a new method for preparing activated carbon from biomass materials and its application on supercapacitor electrodes.

Background technique:

Global warming and the increasing depletion of fossil fuels are forcing people to vigorously develop sustainable and renewable energy sources. At present, solving the increasingly scarce energy problem is still one of the great challenges facing mankind. In the search for clean, efficient and renewable energy, energy storage cannot be ignored. For example, solar energy and wind energy, which are considered to be the most promising new energy sources, are affected by factors such as time, location, and weather, and cannot work stably. Therefore, it is particularly necessary for an energy storage system to store energy and then utilize it. In recent years, supercapacitors have played an increasingly important role as energy storage devices. Especially with the rapid development of new technologies in the fields of information technology, electronic products, and vehicle energy, people have paid more attention to the research and development of supercapacitors.

Biomass, especially agricultural and forestry waste and food residues, contains extremely high levels of cellulose, hemicellulose and lignin, and these components can be processed at high temperatures to obtain carbon-rich materials. my country is a large agricultural country, and a large amount of agricultural and forestry waste is produced every year. The current cleaning method of these materials is mainly incineration, which not only causes serious pollution to the environment, but also is a great waste of resources. Therefore, how to dispose of biomass waste Harmless treatment and reuse is a key topic that is generally concerned by the scientific research community and the industrial circle. However, because biomass still contains many impurities such as metals, the carbon electrode materials directly prepared from biomass on the market have the disadvantages of impure components and poor performance. Green high-purity carbonization, reuse and development of biomass and then applied to the field of energy storage have great economic value and practical significance.

Invention content:

The object of the present invention is to provide a novel method for preparing activated carbon by utilizing biomass with high fiber content under the action of an acidic environment, and the application of the activated carbon prepared by the method in making supercapacitor electrode materials. The method provided by the invention can not only make effective use of biomass waste resources and alleviate the pressure on the ecological environment, but also the prepared activated carbon has good electrochemical performance and can be used as an electrode material for supercapacitors, which is conducive to promoting new energy field development.

A method for preparing activated carbon from biomass, using biomass as a raw material to carry out an open hydrothermal reaction under the action of an acid solution to prepare a carbon precursor, mixing and grinding the carbon precursor and alkaline activator powder, and activating at high temperature to obtain .

As a further preference, the dried and pulverized biomass is mixed with a certain concentration of acid solution, soaked, placed in an open hydrothermal reaction kettle, and kept at 180-250° C. for 5-8 hours to react to obtain a carbon precursor.

As a further preference, the biomass is dried in a blast oven at 80° C. for 24-48 hours. Crush to 30-50 mesh.

As a further preference, the dried and pulverized biomass is mixed with an acid solution of a certain concentration according to the solid-liquid weight volume ratio of 1g:15-30ml, and the acid solution of a certain concentration is phosphoric acid with a mass concentration of 70-85%. Or 60-80% concentrated sulfuric acid, after soaking for 1-2h, put it in an open hydrothermal reaction kettle, and keep it warm for 5-8h at 180-250°C to react to obtain a carbon precursor.

As a further preference, the dried and pulverized biomass is mixed with an acid solution of a certain concentration, soaked, placed in an open hydrothermal reaction kettle, heated in a muffle furnace, and kept warm to obtain a carbon precursor.

As a further preference, the volume of the open hydrothermal reactor is 50-300ml, and the volume of the reaction solution is 60-70% of the volume of the reactor.

As a further preference, the open hydrothermal reactor system is a high-temperature-resistant polytetrafluoroethylene liner with a flange-type movable steel sleeve.

In the method for preparing activated carbon from biomass, the carbon precursor is naturally cooled, washed to neutrality, filtered and dried, mixed with a certain proportion of alkaline activator and ground, and the alkaline activator is preferably KOH, _NaOH , K2 One or more of CO ₃ , Na ₂ CO ₃ , NaHCO ₃ ; placed in a protective atmosphere for high-temperature activation, naturally cooled to room temperature, washed until neutral, and dried.

As a further preference, after natural cooling, the carbon precursor is washed with water until it is neutral, and after suction filtration and drying, the ratio of the carbon precursor to the alkaline activator is 1:1-5, mixed and ground, and placed at 700°C under the protection of a nitrogen atmosphere. Insulate in a tubular high-temperature muffle furnace at -1200°C for 1-8h, cool to room temperature naturally, wash with deionized water and 1M HCl solution respectively, then wash with deionized water until neutral, vacuum filter and dry at 80°C 12h, that is.

The nitrogen atmosphere is nitrogen with a purity of more than 99%; the flow rate of the nitrogen atmosphere is 3-8ml/min; the heating rate of the tubular high-temperature muffle furnace is 3-10°C/min.

In the method for preparing activated carbon from biomass, the biomass has agricultural and forestry wastes and food residues with high cellulose content, including one or more of straw, miscanthus, vines, and fruit peels.

Take by weighing 0.8g of the above-mentioned activated carbon material after grinding, mix it with acetylene black in a weight ratio of 8:1 and grind and mix evenly, then add a small amount of polytetrafluoroethylene aqueous solution with a concentration of 10%, wherein, activated carbon: acetylene black: Polytetrafluoroethylene = 8:1:1 (mass ratio), add a small amount of alcohol as a solvent, mix well, continue grinding and rolling to prepare carbon electrode materials. The prepared carbon electrode sheet was pressed onto a stainless steel current collector, and then vacuum-dried at 110°C for 12 hours, then assembled into a supercapacitor with 6 mol/L KOH aqueous solution as the electrolyte, and the electrochemical performance was tested.

The particle size of the activated carbon material obtained by the method of the present invention is uniform, and the specific surface area is about ^875m2 /g. After the electrode is assembled into a supercapacitor, the discharge specific capacity is 405.34F/g, which has good cycle stability and can be used for energy storage. field. The method uses industrial waste carbon felt leftovers to prepare carbon electrode materials for supercapacitors in a simple and rapid method, turns waste into treasure, fully utilizes resources, reduces environmental pollution, has good economic benefits, and is beneficial to industrial production.

Description of drawings:

Fig. 1: adopt the scanning electron micrograph of the activated carbon for supercapacitor prepared by the embodiment of the present invention 2;

Fig. 2: the cyclic voltammogram at a scan rate of 100mV/s after the activated carbon prepared in Example 2 of the present invention is assembled into a supercapacitor;

Fig. 3: The charge-discharge curve diagram under the current density of 1A/g after the activated carbon prepared by the embodiment 2 of the present invention is assembled into a supercapacitor;

Figure 4: The cycle stability of the activated carbon prepared in Example 2 of the present invention assembled into a supercapacitor under the charge-discharge condition of a current density of 10A/g.

detailed description:

The features of the present invention are described below, and the examples given are only for explaining the present invention, and are not intended to limit the scope of the present invention. Those skilled in the art should understand that equivalent replacements or corresponding improvements to the technical features of the content of the present invention still fall within the protection scope of the present invention.

Embodiment 1: adopt biomass waste material to prepare the preparation method of the active carbon material that can be used for super capacitor electrode comprise the following steps:

Dry the straw in a blast oven to constant weight and then pulverize it, mix it with 75% sulfuric acid solution at a solid-to-liquid weight-volume ratio of 1g:30ml, soak it for 1h, and place it in an improved open hydrothermal reaction kettle system. Heated to 220°C in the air in a muffle furnace, and kept warm for 5 hours to react to obtain a carbon precursor. After natural cooling, it was washed with water until it was neutral. After suction filtration and drying, it was mixed and ground with KOH powder at a ratio of 1:1, and placed in a nitrogen atmosphere for protection. Insulate in a tube-type high-temperature muffle furnace at 800°C for 2h, cool to room temperature naturally, wash with deionized water and 1M HCl solution respectively, then wash with deionized water until neutral, vacuum filter and dry at 80°C for 12h , after grinding, an activated carbon material with good electrochemical performance and which can be used as an electrode material for a supercapacitor can be obtained.

Embodiment 2: adopt biomass waste material to prepare the preparation method of the active carbon material that can be used for supercapacitor electrode comprise the following steps:

Dry Miscanthus in a blast oven to constant weight and pulverize it, mix it with 85% phosphoric acid solution according to the solid-to-liquid weight volume ratio of 1g:20ml, soak it for 1h and place it in the improved open hydrothermal reaction kettle system. Heated to 200°C in the air in a muffle furnace, and kept warm for 5 hours to react to obtain a carbon precursor. After natural cooling, it was washed with water until it was neutral. After suction filtration and drying, it was mixed and ground with KOH powder at a ratio of 1:1, and placed in a nitrogen atmosphere for protection. Insulate in a tube-type high-temperature muffle furnace at 800°C for 2h, cool to room temperature naturally, wash with deionized water and 1M HCl solution respectively, then wash with deionized water until neutral, vacuum filter and dry at 80°C for 12h , after grinding, an activated carbon material with good electrochemical performance and which can be used as an electrode material for a supercapacitor can be obtained.

Embodiment 3: adopt biomass waste material to prepare the preparation method of the active carbon material that can be used for supercapacitor electrode comprise the following steps:

Dried the pericarp in a blast oven to constant weight and pulverized it, mixed it with 75% sulfuric acid solution at a solid-to-liquid weight-volume ratio of 1g:30ml, soaked it for 1h and placed it in an improved open hydrothermal reaction kettle system. Heated to 220°C in the air in a muffle furnace, and kept warm for 8 hours to react to obtain a carbon precursor. After natural cooling, it was washed with water until neutral. After suction filtration and drying, it was mixed and ground with KOH powder at a ratio of 1:1, and placed in a nitrogen atmosphere for protection. Insulate in a tubular high-temperature muffle furnace at 700°C for 2h, cool to room temperature naturally, wash with deionized water and 1M HCl solution, then wash with deionized water until neutral, vacuum filter and dry at 80°C for 12h , after grinding, an activated carbon material with good electrochemical performance and which can be used as an electrode material for a supercapacitor can be obtained.

Comparative example:

Take the pericarp and dry it in a blast oven to constant weight, then pulverize it, mix it with 75% sulfuric acid solution according to the solid-to-liquid weight volume ratio of 1g:30ml, soak it for 1h, place it in a common closed hydrothermal reaction system, and place it in a horse Heated to 220°C in the air in a Furnace, and kept warm for 8 hours to react to obtain a carbon precursor. After natural cooling, it was washed with water until it was neutral. After suction filtration and drying, it was mixed and ground with KOH powder at a ratio of 1:1, and placed in a nitrogen atmosphere. Incubate in a tubular high-temperature muffle furnace at 700°C for 2 hours, cool to room temperature naturally, wash with deionized water and 1M HCl solution respectively, then wash with deionized water until neutral, vacuum filter and dry at 80°C for 12 hours to obtain The carbon material is prepared in the same way as the electrode sheet, and tested in a capacitor device. Its electrochemical performance is far inferior to that of the activated carbon product treated by this method.

Adopt the method of the present invention to prepare gained activated carbon with biomass waste material, be prepared into electrode sheet and pack in the supercapacitor device and test, wherein the scanning electron microscope picture of the supercapacitor electrode activated carbon obtained in embodiment 2 is as shown in Figure 1 , the electrochemical properties are shown in Figures 2, 3, and 4, and the experimental test results of Examples 1-3 and Comparative Examples are shown in Table 1. From the experimental results, the activated carbon material obtained in Example 2 has a uniform particle size and a specific surface area of 875m ² /g, and the prepared supercapacitor has a discharge specific capacity of 405.34F/g, and has good cycle stability .

Table 1

In summary, using the method provided by the present invention to immerse the biomass waste in an acid solution and react in an open system with solvothermal reaction: on the one hand, the biomass waste is used as the processing object to realize the recycling of resources, effectively Reduce environmental pollution and reduce production costs; on the other hand, the preparation process is simple, the process is simple, and the cost is low, and the obtained activated carbon product has good electrochemical properties and can be used in the field of energy storage; the source of raw materials is wide, the production process is simple, and it is suitable for Industrial promotion and application.

Claims (10)

1. A kind of 1. method that activated carbon is prepared using biomass, it is characterised in that acted on using biomass for raw material in acid solution It is lower to carry out open hydro-thermal reaction and prepare carbon matrix precursor, carbon matrix precursor and alkali activator powder mixed grinding, high-temperature activation, Produce.
2. 2. the method according to claim 1 that activated carbon is prepared using biomass, it is characterised in that after drying and crushing Biomass mixes with certain density acid solution, after immersion, is placed in unlimited hydrothermal reaction kettle, at 180-250 DEG C, is incubated 5- 8h reacts to obtain carbon matrix precursor.
3. 3. the method according to claim 2 that activated carbon is prepared using biomass, it is characterised in that after drying and crushing Biomass is 1g by solid-liquid w/v with certain density acid solution:15-30ml is mixed, and described certain density acid is molten Liquid is the phosphoric acid that mass concentration is 70-85% or the 60-80% concentrated sulfuric acid, after soaking 1-2h, is placed in unlimited hydrothermal reaction kettle In, at 180-250 DEG C, insulation 5-8h reacts to obtain carbon matrix precursor.
4. 4. the method according to claim 2 that activated carbon is prepared using biomass, it is characterised in that after drying and crushing Biomass mixes with certain density acid solution, is placed in after immersion in the hydrothermal reaction kettle of open type, is placed in Muffle furnace and heats, Insulation reaction obtains carbon matrix precursor.
5. 5. the method according to claim 1 that activated carbon is prepared using biomass, it is characterised in that open hydrothermal reaction kettle Volume is 50-300ml, and liquid amount is the 60-70% of reactor volume during reaction.
6. 6. the method according to claim 1 that activated carbon is prepared using biomass, it is characterised in that carbon matrix precursor is naturally cold But wash afterwards to neutrality, filter after drying with a certain proportion of alkali activator powder mixed grinding, alkali activator KOH, NaOH、K₂CO₃、Na₂CO₃、NaHCO₃In one or more；High-temperature activation under protective atmosphere is placed in, after naturally cooling to room temperature, Washing is dried, produced to neutrality.
7. 7. the method according to claim 6 that activated carbon is prepared using biomass, it is characterised in that carbon matrix precursor is naturally cold But afterwards using washing until neutral, after suction filtration is dried, the ratio of carbon matrix precursor and alkali activator is 1：1-5 mixed grindings, put 1-8h is incubated in 700 DEG C -1200 DEG C of the tubular type high temperature Muffle furnace under nitrogen atmosphere protection, after naturally cooling to room temperature, is adopted Washed, be then washed with deionized to neutrality respectively with deionized water, 1MHCl solution, is filtered by vacuum after 80 DEG C of dryings 12h, produce.
8. 8. the method according to claim 1 that activated carbon is prepared using biomass, it is characterised in that biomass has fiber The agriculture and forestry organic waste material and food residue thing of plain high content, including：One or more in stalk, Chinese silvergrass, tendril, pericarp.
9. 9. activated carbon prepared by the method described in claim any one of 1-8.
10. 10. the application of the activated carbon described in claim 9, it is characterised in that for preparing ultracapacitor active carbon electrode Material.