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

Abstract

The application 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 high-silicon biomass to obtain activated carbon. According to the method, specific treatment processes are performed on the high-silicon biomass, so that the high-silicon biomass can be prepared into activated carbon which has a good adsorption effect on butane, the adsorption amount of butane is greater than 0.5 g / g, and the specific surface area of the obtained activated carbon is greater than or equal to 1500 m 2 / g and the mesopore ratio is greater than or equal to 43%.

Description

Technical Field

[0001] This invention relates to the field of activated carbon technology, specifically to a method for preparing activated carbon using high-silicon biomass and the uses of the obtained activated carbon, and more particularly to a method for preparing activated carbon with high specific surface area and mesoporous content using rice husks and the uses of the obtained activated carbon. Background Technology

[0002] The automotive charcoal canister is a crucial component of the fuel evaporation control system. It connects to the fuel tank at one end and is open to the atmosphere at the other. The canister contains activated carbon, which adsorbs and stores fuel vapors emitted from the fuel tank. It can also be regenerated through backflushing, returning the stored fuel vapors to the fuel tank. Therefore, the charcoal canister not only improves fuel efficiency but also controls fuel vapor emissions into the atmosphere. Activated carbon is the core material of the charcoal canister, and its performance directly affects the system's operational capability.

[0003] For example, CN113753891A discloses a wood-based activated carbon for automotive carbon canisters and its preparation technology, as follows:

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

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

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

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

[0008] CN117602620A discloses a granular activated carbon for automotive canisters, its preparation method, and its uses. The preparation method includes the following steps:

[0009] (1) Mix petroleum-based raw materials and activators, and then grind, activate in a variable-diameter fluidized bed, wash and dry in sequence to obtain a precursor;

[0010] (2) The precursor and binder obtained in step (1) are mixed and then molded and dried in sequence to obtain automotive carbon canister granular activated carbon.

[0011] However, the activated carbon obtained by the above scheme has a low specific surface area and a 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 existing activated carbon for carbon canisters, which still have low specific surface area and poor adsorption and desorption capacity.

[0013] To achieve this objective, the present invention adopts the following technical solution:

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

[0015] High-silicon biomass was subjected to pre-activation, carbonization, and alkali treatment in sequence to obtain activated carbon.

[0016] The method provided by this invention, through a specific treatment process on high-silicon biomass, enables the preparation of activated carbon with good butane adsorption capacity, reaching >0.5 g / g, while the specific surface area of ​​the obtained activated carbon is ≥1500 m². 2 / g and mesoporous content ≥43%.

[0017] As a preferred embodiment of the present invention, the silicon content in the high-silicon biomass is ≥17% by mass.

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

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

[0020] Preferably, the activator comprises phosphoric acid and / or ammonium polyphosphate, and more 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 embodiment of the present invention, the temperature of the heat treatment is 150-200℃.

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

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

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

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

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

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

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

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

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

[0032] As a preferred embodiment of the present invention, the material obtained by carbonization before alkali treatment is washed until the pH value of the washing liquid is 5-6.

[0033] Preferably, after the alkali treatment, solid-liquid separation is performed, and the resulting solid is activated carbon.

[0034] In a second aspect, the present invention provides a use for the activated carbon obtained by the method described in the first aspect, the use including:

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

[0036] Compared with existing technical solutions, the present invention has the following beneficial effects:

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

[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 formulation with a mass ratio of phosphoric acid and ammonium polyphosphate of 1:(0.4-0.6), the activated carbon prepared can adsorb butane at a capacity of >1g / g, and the specific surface area of ​​the obtained activated carbon is ≥2000m². 2 / g and mesoporous content ≥50%. Detailed Implementation

[0039] To better illustrate the present invention and facilitate understanding of its technical solutions, 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] High-silicon biomass was subjected to pre-activation, carbonization, and alkali treatment in sequence to obtain activated carbon.

[0042] Wherein, the silicon mass percentage content 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 this invention, the high-silicon biomass includes biomass such as rice husks that meet the specified silicon content requirements in the art.

[0044] The pre-activation includes: mixing the activator with high-silicon biomass and then subjecting it to heat treatment.

[0045] The mass ratio of activator to high-silicon biomass in the pre-activation process 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, etc., but is not limited to the listed values. Other unlisted values ​​within this range also meet the requirements.

[0046] The activator includes phosphoric acid and / or ammonium polyphosphate.

[0047] The mass concentration of phosphoric acid is 50-70%, for example, it can be 50%, 55%, 60%, 65% or 70%, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0048] Among them, the activated carbon obtained when the activating agent is phosphoric acid and ammonium polyphosphate in a mass ratio of 1:(0.4-0.6) exhibits superior performance. The activated carbon prepared with this method can adsorb butane at a capacity of >1 g / g, and the specific surface area of ​​the obtained activated carbon is ≥2000 m². 2 / g and mesoporous content ≥50%.

[0049] The heat treatment temperature is 150-200℃, for example, it can be 150℃, 155℃, 160℃, 165℃, 170℃, 175℃, 180℃, 185℃, 190℃, 195℃ or 200℃, but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0050] The heat treatment time is 1-2 hours, for example, it can be 1 hour, 1.2 hours, 1.4 hours, 1.6 hours, 1.8 hours or 2 hours, but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0051] The carbonization is carried out under an inert atmosphere.

[0052] In this 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 carbonization, such as nitrogen, helium, neon, or argon.

[0053] The carbonization temperature is 400-500℃, for example, it can be 400℃, 410℃, 420℃, 430℃, 440℃, 450℃, 460℃, 470℃, 480℃, 490℃ or 500℃, but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0054] The carbonization time is 1-3 hours, for example, it can be 1 hour, 1.2 hours, 1.4 hours, 1.6 hours, 1.8 hours, 2 hours, 2.2 hours, 2.4 hours, 2.6 hours, 2.8 hours or 3 hours, but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0055] The alkaline treatment includes treating the carbonized material with an alkaline solution.

[0056] The mass ratio of alkali to high-silica biomass in the alkali solution used for alkali treatment 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. Other unlisted values ​​within this range also meet the requirements.

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

[0058] The concentration of the alkaline 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 unlisted values ​​within this range are also acceptable.

[0059] The alkali treatment time is 5-30 minutes, for example, it can be 5 minutes, 10 minutes, 15 minutes, 20 minutes, 25 minutes or 30 minutes, but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0060] The material obtained from carbonization before alkali treatment is washed until the pH value of the washing liquid is 5-6, such as 5, 5.2, 5.4, 5.6, 5.8 or 6, but not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

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

[0062] In this invention, the filtrate obtained from solid-liquid separation can be used to prepare sodium silicate solid or silica.

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

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

[0065] For example, the activated carbon may be used to adsorb automotive fuel vapors, or to adsorb butane, or to adsorb isopentane, or to adsorb indoor odors such as formaldehyde and / or VOCs.

[0066] Furthermore, to illustrate the excellent gaseous pollutant removal effect of the activated carbon prepared by this invention, the following practical example is provided for illustrative purposes:

[0067] Example 1

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

[0069] High-silicon biomass was subjected to pre-activation, carbonization and alkali treatment in sequence to obtain activated carbon;

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

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

[0072] The carbonization was carried out in an inert atmosphere (helium) at a temperature of 500°C for 2 hours.

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

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

[0075] Example 2

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

[0077] High-silicon biomass was subjected to pre-activation, carbonization and alkali treatment in sequence to obtain activated carbon;

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

[0079] The pre-activation includes: mixing an activator with high-silica biomass and then subjecting it to heat treatment. The mass ratio of the activator to the high-silica biomass in the pre-activation is 1:1. The activator is phosphoric acid with a mass concentration of 60%. The heat treatment temperature is 160°C and the time is 2 hours.

[0080] The carbonization was carried out in an inert atmosphere (neon) at a temperature of 500°C for 2 hours.

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

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

[0083] Example 3

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

[0085] High-silicon biomass was subjected to pre-activation, carbonization and alkali treatment in sequence to obtain activated carbon;

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

[0087] The pre-activation includes: mixing an activator with high-silica biomass and then subjecting it to heat treatment. The mass ratio of the activator to the high-silica biomass in the pre-activation is 1.5:1. The activator is phosphoric acid with a mass concentration of 70%. The heat treatment temperature is 150°C and the time is 2 hours.

[0088] The carbonization is carried out under an inert atmosphere (nitrogen) at a temperature of 450°C for 3 hours.

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

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

[0091] Example 4

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

[0093] High-silicon biomass was subjected to pre-activation, carbonization and alkali treatment in sequence to obtain activated carbon;

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

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

[0096] The carbonization was carried out in an inert atmosphere (helium) at a temperature of 400°C for 3 hours.

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

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

[0099] Example 5

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

[0101] Example 6

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

[0103] Example 7

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

[0105] Example 8

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

[0107] Example 9

[0108] The only difference from Example 1 is that phosphoric acid is replaced with 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 with equal amounts of phosphoric acid and ammonium polyphosphate in a mass ratio of 1:0.4.

[0111] Example 11

[0112] The only difference from Example 3 is that phosphoric acid is replaced with 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 with equal amounts of phosphoric acid and ammonium polyphosphate in a mass ratio of 1:0.55.

[0115] Example 13

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

[0117] Example 14

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

[0119] Example 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 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 subjected to carbonization, alkali treatment and pre-activation in sequence.

[0125] Comparative Example 2

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

[0127] Comparative Example 3

[0128] The only difference from Example 1 is that no pre-activation is performed.

[0129] Comparative Example 4

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

[0131] The activated carbon obtained in the examples was subjected to performance testing. The specific test was conducted according to the national standard GB / T20449-2006 to determine the butane adsorption capacity to evaluate the performance of the activated carbon. The specific surface area and mesoporous content were calculated based on the HK model and the BJH model.

[0132] Table 1

[0133]

[0134]

[0135] As shown in Table 1, this invention utilizes 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. Then, mesopores are created through etching, ultimately obtaining a carbon material with high mesopore rate and high specific surface area. This material was then used for butane adsorption, achieving good adsorption results.

[0136] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within 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 describe the various possible combinations separately.

[0138] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A method for preparing activated carbon using high-silicon biomass, characterized in that, The method includes: Rice husks are subjected to pre-activation, carbonization and alkali treatment in sequence to obtain activated carbon; The pre-activation includes: mixing the activator with high-silicon biomass and then subjecting it to heat treatment; The activator comprises: phosphoric acid and ammonium polyphosphate in a mass ratio of 1:(0.4-0.6); The carbonization is carried out under an inert atmosphere; the carbonization temperature is 400-500℃.

2. The method as described in claim 1, characterized in that, In the pre-activation process, the mass ratio of activator to high-silicon biomass is (0.5-2):

1.

3. The method as described in claim 1, characterized in that, The mass concentration of the phosphoric acid is 50-70%.

4. The method as described in claim 1, characterized in that, The heat treatment temperature is 150-200℃.

5. The method as described in claim 1, characterized in that, The heat treatment time is 1-2 hours.

6. The method as described in claim 1, characterized in that, The carbonization time is 1-3 hours.

7. The method as described in claim 1, characterized in that, The alkaline treatment includes treating the carbonized material with an alkaline solution.

8. The method as described in claim 7, characterized in that, The mass ratio of alkali to high-silica biomass in the alkali solution used for alkali treatment is (0.3-0.8):

1.

9. The method as described in claim 7, characterized in that, The alkali in the alkaline solution includes sodium hydroxide and / or potassium hydroxide.

10. The method as described in claim 7, characterized in that, The concentration of the alkaline solution is 50-75 g / L.

11. The method as described in claim 1, characterized in that, The alkali treatment time is 5-30 minutes.

12. The method as described in claim 1, characterized in that, The material obtained from carbonization before alkali treatment is washed until the pH of the washing solution is 5-6.

13. The method as described in claim 1, characterized in that, After alkali treatment, solid-liquid separation is performed, and the resulting solid is activated carbon.

14. Use of activated carbon obtained by the method according to any one of claims 1-13, characterized in that, The uses include: The activated carbon is used to adsorb volatile organic gases.

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