Method for preparing activated carbon from high-silicon biomass and application of obtained activated carbon

Abstract

The invention relates to a method for preparing activated carbon from high-silicon biomass and application of the obtained activated carbon, in particular to the technical field of activated carbon, and the method comprises the following steps: sequentially performing pre-activation, carbonization and alkali treatment on the high-silicon biomass to obtain the activated carbon. According to the method provided by the invention, the high-silicon biomass can be prepared into the activated carbon with a good butane adsorption effect by carrying out a specific treatment process on the high-silicon biomass, the butane adsorption capacity is greater than 0.5 g / g, and meanwhile, the specific surface area of the obtained activated carbon is greater than or equal to 1,500 m < 2 > / g and the mesoporous rate is greater than or equal to 43%.

Description

Technical Field

[0001] The present invention relates to the technical field of activated carbon, and specifically to a method for preparing activated carbon by utilizing high-silicon biomass and uses of the obtained activated carbon, and in particular to a method for preparing activated carbon with high specific surface area and mesoporosity by utilizing rice husk and uses of the obtained activated carbon. Background Art

[0002] The car charcoal canister is an important part of the fuel evaporation control system. It is connected to the fuel tank at one end and the atmosphere at the other end. The charcoal canister is loaded with activated carbon, which can absorb and store the vapor volatilized from the fuel tank; and can be regenerated by back-blowing to return the stored fuel vapor to the fuel tank. Therefore, the charcoal canister can not only improve the efficiency of fuel use, but also control the emission of fuel vapor into the atmosphere. Activated carbon is the core material of the charcoal canister, and its performance will directly affect the working ability of the charcoal canister system.

[0003] For example, CN113753891A discloses a kind of wood activated carbon for vehicle canister and its preparation technology, as follows:

[0004] 1. After mixing and sieving peach shell powder and other wood powders in a certain mass ratio, add phosphoric acid for aging, and then add 5-20wt% of zinc chloride and other pore-enlarging agents for kneading.

[0005] 2. The product is mixed with 1%-10wt% of a binder such as sodium carboxymethyl cellulose and extruded at high temperature.

[0006] 3. The molded product is hardened at 180-250°C for 12-36 hours, and then activated at 450-700°C for 1-4 hours under a protective atmosphere.

[0007] 4. After the activated product is washed, dried and sieved, activated carbon particles can be obtained.

[0008] CN117602620A discloses a kind of automobile carbon canister granular activated carbon and its preparation method and use, the preparation method comprises the following steps:

[0009] (1) mixing a petroleum-based raw material and an activator, and then sequentially grinding, variable diameter fluidized bed activation, washing and drying to obtain a precursor;

[0010] (2) Mixing the precursor and the binder obtained in step (1), and then sequentially performing molding and drying and hardening to obtain automobile carbon canister granular activated carbon.

[0011] However, the activated carbon obtained by the above scheme has a low specific surface area and has the defect of poor butane adsorption capacity. Summary of the invention

[0012] In view of the problems existing in the prior art, the purpose of the present invention is to provide a method for preparing activated carbon using high-silicon biomass, so as to solve the defects of the existing activated carbon for carbon canisters, that is, the low specific surface area and poor adsorption and desorption capacity.

[0013] To achieve this object, the present invention adopts the following technical solutions:

[0014] In a first aspect, the present invention provides a method for preparing activated carbon using high-silicon biomass, the method comprising:

[0015] The high-silicon biomass is sequentially pre-activated, carbonized and treated with alkali to obtain activated carbon.

[0016] The method provided by the present invention can prepare high-silicon biomass into activated carbon with good butane adsorption effect by performing a specific treatment process on high-silicon biomass, and the adsorption amount of butane can reach >0.5g / g, and the specific surface area of ​​the obtained activated carbon is ≥1500m 2 / g and mesoporosity ≥43%.

[0017] As a preferred technical solution of the present invention, the mass percentage of silicon in the high-silicon biomass is ≥17%.

[0018] As a preferred technical solution of the present invention, the pre-activation comprises: mixing the activator with the high-silicon biomass and then performing heat treatment.

[0019] As a preferred technical solution of the present invention, the mass ratio of the activator to the high-silicon biomass in the pre-activation is (0.5-2):1.

[0020] Preferably, the activator comprises phosphoric acid and / or ammonium polyphosphate, preferably phosphoric acid and ammonium polyphosphate in a mass ratio of 1:(0.4-0.6).

[0021] Preferably, the mass concentration of the phosphoric acid is 50-70%.

[0022] As a preferred technical solution of the present invention, the temperature of the heat treatment is 150-200°C.

[0023] Preferably, the heat treatment time is 1-2 hours.

[0024] As a preferred technical solution of the present invention, the carbonization is carried out under an inert atmosphere.

[0025] Preferably, the carbonization temperature is 400-500°C.

[0026] Preferably, the carbonization time is 1-3 hours.

[0027] As a preferred technical solution of the present invention, the alkali treatment includes treating the carbonized material with alkali solution.

[0028] Preferably, the mass ratio of alkali in the alkali solution used for the alkali treatment to high-silicon biomass is (0.3-0.8):1.

[0029] Preferably, the alkali in the alkali solution comprises sodium hydroxide and / or potassium hydroxide.

[0030] Preferably, the concentration of the alkali solution is 50-75 g / L.

[0031] As a preferred technical solution of the present invention, the alkali treatment time is 5-30 minutes.

[0032] As a preferred technical solution of the present invention, the carbonized material is washed until the pH value of the washing liquid is 5-6 before the alkali treatment.

[0033] Preferably, the alkali treatment is followed by solid-liquid separation, and the obtained solid is activated carbon.

[0034] In a second aspect, the present invention provides a use of activated carbon obtained by the method according to the first aspect, the use comprising:

[0035] The activated carbon is used to adsorb organic volatile gases.

[0036] Compared with the prior art solutions, the present invention has the following beneficial effects:

[0037] (1) The preparation method provided by the present invention broadens the application scope of raw materials for high-performance activated carbon, and proposes a method of first constructing micropores and then desiliconizing to construct mesopores, thereby using raw materials with high silicon content to prepare activated carbon with high specific surface area, while producing silicon products as a by-product.

[0038] (2) The present invention provides a simple method for preparing high-performance activated carbon powder, with mild reaction conditions, short process and easy industrialization; at the same time, under the preferred activator formula of phosphoric acid and ammonium polyphosphate with a mass ratio of 1: (0.4-0.6), the adsorption capacity of butane by the prepared activated carbon can reach >1g / g, and the specific surface area of ​​the obtained activated carbon is ≥2000m 2 / g and mesoporosity ≥50%. DETAILED DESCRIPTION

[0039] To better illustrate the present invention and facilitate understanding of the technical solution of the present invention, typical but non-limiting embodiments of the present invention are as follows:

[0040] This embodiment provides a method for preparing activated carbon using high-silicon biomass, the method comprising:

[0041] The high-silicon biomass is sequentially pre-activated, carbonized and treated with alkali to obtain activated carbon.

[0042] Among them, the mass percentage of silicon in the high-silicon biomass is ≥17%, for example, it can be 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27% or 28%, etc., but is not limited to the listed values, and other unlisted values ​​within this range also meet the requirements.

[0043] In the present invention, the high-silicon biomass includes rice husks and other biomass whose silicon content meets the specified requirements in the art.

[0044] Wherein, the pre-activation comprises: mixing an activator with high-silicon biomass and then performing heat treatment.

[0045] Among them, the mass ratio of the activator to the high-silicon biomass in the pre-activation is (0.5-2):1, for example, it can be 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1 or 2:1, but is not limited to the listed values, and other unlisted values ​​within this range also meet the requirements.

[0046] Wherein, the activator includes phosphoric acid and / or ammonium polyphosphate.

[0047] The mass concentration of the phosphoric acid is 50-70%, for example, 50%, 55%, 60%, 65% or 70%, etc., but is not limited to the listed values, and other values ​​not listed within the range also meet the requirements.

[0048] Among them, when the activator is phosphoric acid and ammonium polyphosphate with a mass ratio of 1: (0.4-0.6), the obtained activated carbon has more excellent performance. The adsorption capacity of butane by the prepared activated carbon can reach >1g / g, and the specific surface area of ​​the obtained activated carbon is ≥2000m 2 / g and mesoporosity ≥50%.

[0049] Wherein, the temperature of the heat treatment is 150-200°C, for example, it can be 150°C, 155°C, 160°C, 165°C, 170°C, 175°C, 180°C, 185°C, 190°C, 195°C or 200°C, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0050] The heat treatment time is 1-2h, for example, 1h, 1.2h, 1.4h, 1.6h, 1.8h or 2h, but is not limited to the listed values, and other values ​​not listed within the range also meet the requirements.

[0051] Wherein, the carbonization is carried out under an inert atmosphere.

[0052] In the present invention, the inert atmosphere includes one or a combination of at least two of the gases commonly used in the art that do not affect the carbonization process, such as nitrogen, helium, neon or argon.

[0053] Wherein, the carbonization temperature is 400-500°C, for example, it can be 400°C, 410°C, 420°C, 430°C, 440°C, 450°C, 460°C, 470°C, 480°C, 490°C or 500°C, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0054] The carbonization time is 1-3h, for example, 1h, 1.2h, 1.4h, 1.6h, 1.8h, 2h, 2.2h, 2.4h, 2.6h, 2.8h or 3h, but is not limited to the listed values, and other values ​​not listed within the range also meet the requirements.

[0055] Wherein, the alkali treatment includes treating the carbonized material with alkali solution.

[0056] Among them, the mass ratio of alkali in the alkali solution used for the alkali treatment to high-silicon biomass is (0.3-0.8):1, for example, it can be 0.3:1, 0.35:1, 0.4:1, 0.45:1, 0.5:1, 0.55:1, 0.6:1, 0.65:1, 0.7:1, 0.75:1 or 0.8:1, but is not limited to the listed values, and other unlisted values ​​within this range also meet the requirements.

[0057] The alkali in the alkali solution includes sodium hydroxide and / or potassium hydroxide, and further sodium bicarbonate or the like may also be used.

[0058] The concentration of the alkali solution is 50-75 g / L, for example, it can be 50 g / L, 55 g / L, 60 g / L, 65 g / L, 70 g / L or 75 g / L, but is not limited to the listed values. Other values ​​not listed within the range also meet the requirements.

[0059] The alkali treatment time is 5-30 min, for example, 5 min, 10 min, 15 min, 20 min, 25 min or 30 min, but is not limited to the listed values, and other values ​​not listed within the range also meet the requirements.

[0060] Wherein, before the alkali treatment, the carbonized material is washed until the pH value of the washing liquid is 5-6, for example, it can be 5, 5.2, 5.4, 5.6, 5.8 or 6, but is not limited to the listed values, and other values ​​not listed within the range also meet the requirements.

[0061] Wherein, solid-liquid separation is performed after the alkali treatment, and the obtained solid is activated carbon.

[0062] In the present invention, the filtrate obtained by solid-liquid separation can be used to prepare sodium silicate solid or white carbon black.

[0063] Furthermore, the uses of the activated carbon obtained above in the present invention include:

[0064] The activated carbon is used to adsorb organic volatile gases.

[0065] For example, the activated carbon is used to adsorb automobile fuel vapor, or the activated carbon is used to adsorb butane, or the activated carbon is used to adsorb isopentane, or the activated carbon is used to adsorb indoor odors such as formaldehyde and / or VOCs.

[0066] Further, in order to illustrate that the activated carbon prepared by the present invention can achieve good gaseous pollutant removal effect, the following actual example is used for exemplary description, as follows:

[0067] Example 1

[0068] This embodiment provides a method for preparing activated carbon using high-silicon biomass, comprising:

[0069] The high-silicon biomass is sequentially pre-activated, carbonized and treated with alkali to obtain activated carbon;

[0070] The high-silicon biomass is rice husk;

[0071] The pre-activation comprises: mixing an activator with high-silicon biomass and then performing heat treatment; in the pre-activation, the mass ratio of the activator to the high-silicon biomass is 1.5:1, the activator is phosphoric acid, the mass concentration of the phosphoric acid is 70%, the heat treatment temperature is 180°C, and the time is 2 hours;

[0072] The carbonization is carried out under an inert atmosphere (helium), the carbonization temperature is 500° C., and the carbonization time is 2 h;

[0073] The alkali treatment includes treating the carbonized material with alkali solution, the mass ratio of alkali in the alkali solution used for the alkali treatment to high-silicon biomass is 0.5:1, the alkali in the alkali solution is sodium hydroxide, the concentration of the alkali solution is 50g / L, and the alkali treatment time is 20min; before the alkali treatment, the carbonized material is washed until the pH value of the washing solution is 6;

[0074] After the alkali treatment, solid-liquid separation is performed, and the obtained solid is activated carbon.

[0075] Example 2

[0076] This embodiment provides a method for preparing activated carbon using high-silicon biomass, comprising:

[0077] The high-silicon biomass is sequentially pre-activated, carbonized and treated with alkali to obtain activated carbon;

[0078] The high-silicon biomass is rice husk;

[0079] The pre-activation comprises: mixing an activator with high-silicon biomass and then performing heat treatment, wherein the mass ratio of the activator to the high-silicon biomass in the pre-activation is 1:1, the activator is phosphoric acid, the mass concentration of the phosphoric acid is 60%, the heat treatment temperature is 160°C, and the time is 2 hours;

[0080] The carbonization is carried out under an inert atmosphere (neon gas) at a temperature of 500° C. for 2 h.

[0081] The alkali treatment includes treating the carbonized material with alkali solution, the mass ratio of alkali in the alkali solution used for the alkali treatment to high-silicon biomass is 0.5:1, the alkali in the alkali solution is sodium hydroxide, the concentration of the alkali solution is 50g / L, and the alkali treatment time is 30min; before the alkali treatment, the carbonized material is washed until the pH value of the washing solution is 5;

[0082] After the alkali treatment, solid-liquid separation is performed, and the obtained solid is activated carbon.

[0083] Example 3

[0084] This embodiment provides a method for preparing activated carbon using high-silicon biomass, comprising:

[0085] The high-silicon biomass is sequentially pre-activated, carbonized and treated with alkali to obtain activated carbon;

[0086] The high-silicon biomass is rice husk;

[0087] The pre-activation comprises: mixing an activator with high-silicon biomass and then performing heat treatment, wherein the mass ratio of the activator to the high-silicon biomass in the pre-activation is 1.5:1, the activator is phosphoric acid, the mass concentration of the phosphoric acid is 70%, the heat treatment temperature is 150° C., and the time is 2 hours;

[0088] The carbonization was carried out under an inert atmosphere (nitrogen), the carbonization temperature was 450° C., and the carbonization time was 3 h;

[0089] The alkali treatment includes treating the carbonized material with alkali solution, the mass ratio of alkali in the alkali solution used for the alkali treatment to high-silicon biomass is 0.5:1, the alkali in the alkali solution is potassium hydroxide, the concentration of the alkali solution is 50g / L, and the alkali treatment time is 20min; before the alkali treatment, the carbonized material is washed until the pH value of the washing solution is 5;

[0090] After the alkali treatment, solid-liquid separation is performed, and the obtained solid is activated carbon.

[0091] Example 4

[0092] This embodiment provides a method for preparing activated carbon using high-silicon biomass, comprising:

[0093] The high-silicon biomass is sequentially pre-activated, carbonized and treated with alkali to obtain activated carbon;

[0094] The high-silicon biomass is rice husk;

[0095] The pre-activation comprises: mixing an activator with high-silicon biomass and then performing heat treatment; in the pre-activation, the mass ratio of the activator to the high-silicon biomass is 0.5:1, the activator is phosphoric acid, the mass concentration of the phosphoric acid is 50%, the heat treatment temperature is 200°C, and the time is 1 hour;

[0096] The carbonization is carried out under an inert atmosphere (helium) at a temperature of 400° C. for 3 h.

[0097] The alkali treatment includes treating the carbonized material with alkali solution, the mass ratio of alkali in the alkali solution used for the alkali treatment to high-silicon biomass is 0.8:1, the alkali in the alkali solution is sodium hydroxide, the concentration of the alkali solution is 70g / L, and the alkali treatment time is 30min; before the alkali treatment, the carbonized material is washed until the pH value of the washing solution is 6;

[0098] After the alkali treatment, solid-liquid separation is performed, and the obtained solid is activated carbon.

[0099] Example 5

[0100] The only difference from Example 1 is that phosphoric acid is replaced by an equal amount of ammonium polyphosphate.

[0101] Example 6

[0102] The only difference from Example 2 is that phosphoric acid is replaced by an equal amount of ammonium polyphosphate.

[0103] Example 7

[0104] The only difference from Example 3 is that phosphoric acid is replaced by an equal amount of ammonium polyphosphate.

[0105] Example 8

[0106] The only difference from Example 4 is that phosphoric acid is replaced by an equal amount of ammonium polyphosphate.

[0107] Example 9

[0108] The only difference from Example 1 is that phosphoric acid is replaced by equal amounts of phosphoric acid and ammonium polyphosphate in a mass ratio of 1:0.5.

[0109] Example 10

[0110] The only difference from Example 2 is that phosphoric acid is replaced by equal amounts of phosphoric acid and ammonium polyphosphate in a mass ratio of 1:0.4.

[0111] Embodiment 11

[0112] The only difference from Example 3 is that phosphoric acid is replaced by equal amounts of phosphoric acid and ammonium polyphosphate in a mass ratio of 1:0.6.

[0113] Example 12

[0114] The only difference from Example 4 is that phosphoric acid is replaced by equal amounts of phosphoric acid and ammonium polyphosphate in a mass ratio of 1:0.55.

[0115] Embodiment 13

[0116] The only difference from Example 1 is that phosphoric acid is replaced by equal amounts of phosphoric acid and ammonium polyphosphate in a mass ratio of 0.5:1.

[0117] Embodiment 14

[0118] The only difference from Example 1 is that phosphoric acid is replaced by equal amounts of sulfuric acid and ammonium polyphosphate in a mass ratio of 1:0.5.

[0119] Embodiment 15

[0120] The only difference from Example 1 is that the carbonization temperature is 200°C.

[0121] Example 16

[0122] The only difference from Example 1 is that the carbonization is carried out in an air atmosphere instead of an inert atmosphere.

[0123] Comparative Example 1

[0124] The only difference from Example 1 is that the high-silicon biomass is carbonized, alkali treated and pre-activated in sequence.

[0125] Comparative Example 2

[0126] The only difference from Example 1 is that the rice husk is replaced by an equal amount of straw.

[0127] Comparative Example 3

[0128] The only difference from Example 1 is that no preactivation was performed.

[0129] Comparative Example 4

[0130] The only difference from Example 1 is that no alkali treatment was performed.

[0131] The activated carbon obtained in the example was subjected to performance testing. Specifically, the performance of the activated carbon was evaluated by measuring the butane adsorption amount according to the national standard GB / T20449-2006, and the specific surface area and mesoporosity were calculated according to the HK model and the BJH model.

[0132] Table 1

[0133]

[0134]

[0135] As can be seen from Table 1, the present invention uses the interaction between carbon and silicon elements in high-silicon biomass through pre-activation, carbonization and alkali treatment processes to pre-generate a material with a high specific surface area, and then creates mesopores by etching, ultimately obtaining a carbon material with high mesoporosity and high specific surface area, and using it for butane adsorption to achieve good adsorption effects.

[0136] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0137] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0138] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A method for preparing activated carbon using high-silicon biomass, characterized in that: The method comprises: The high-silicon biomass is sequentially pre-activated, carbonized and treated with alkali to obtain activated carbon.

2. The method according to claim 1, characterized in that The mass percentage of silicon in the high-silicon biomass is ≥17%.

3. The method according to claim 1 or 2, characterized in that The pre-activation comprises: mixing an activator with high-silicon biomass and then performing heat treatment.

4. The method according to claim 3, characterized in that The mass ratio of the activator to the high-silicon biomass in the pre-activation is (0.5-2):1; Preferably, the activator comprises phosphoric acid and / or ammonium polyphosphate, preferably phosphoric acid and ammonium polyphosphate in a mass ratio of 1:(0.4-0.6); Preferably, the mass concentration of the phosphoric acid is 50-70%.

5. The method according to claim 3 or 4, characterized in that The temperature of the heat treatment is 150-200°C; Preferably, the heat treatment time is 1-2 hours.

6. The method according to any one of claims 1 to 5, characterized in that: The carbonization is carried out under an inert atmosphere; Preferably, the carbonization temperature is 400-500°C; Preferably, the carbonization time is 1-3 hours.

7. The method according to any one of claims 1 to 6, characterized in that: The alkali treatment includes treating the carbonized material with alkali solution; Preferably, the mass ratio of alkali in the alkali solution used for the alkali treatment to high-silicon biomass is (0.3-0.8):1; Preferably, the alkali in the alkali solution comprises sodium hydroxide and / or potassium hydroxide; Preferably, the concentration of the alkali solution is 50-75 g / L.

8. The method according to any one of claims 1 to 7, characterized in that: The alkali treatment time is 5-30 minutes.

9. The method according to any one of claims 1 to 8, characterized in that The carbonized material is washed before the alkali treatment until the pH value of the washing liquid is 5-6; Preferably, the alkali treatment is followed by solid-liquid separation, and the obtained solid is activated carbon.

10. Use of activated carbon obtained by the method according to any one of claims 1 to 9, characterized in that: The uses include: The activated carbon is used to adsorb organic volatile gases.

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