NL2028194B1 - Method of preparing modified activated carbon with phenol and rapid ultralow-temperature freezing - Google Patents

Abstract

A method of preparing modified activated carbon with phenol and rapid ultralow-temperature freezing comprises the following steps: weighing crushed shells as raw materials, soaking the crushed shells in a phosphoric acid solution, mixing the soaked crushed shells with the phenol, drying a mixture, and conducting activation for 0.5 - 24 h at a high temperature of 300 - 1100°C in an oxygen-free environment; after activation, rapidly soaking an activated material in liquid nitrogen at a high temperature or brine ice of -20°C or below, conducting sealed oscillation for 2 h, and then taking out a product; and conducting oscillation cleaning on the product with deionized water until neutral, and drying the product to obtain the modified activated carbon. By using the activated carbon preparation method provided by the present invention, compared with activated carbon obtained by activation with a same concentration of phosphoric acid and natural air cooling, the obtained activated carbon has the advantages that phenolic hydroxyl groups and a specific surface area are both obviously increased, and the energy saving effect is obvious.

Description

METHOD OF PREPARING MODIFIED ACTIVATED CARBON WITH PHENOL AND RAPID ULTRALOW-TEMPERATURE FREEZING Technical Field The present invention belongs to the technical field of activated carbon preparation, and particularly relates to a method of preparing modified activated carbon with phenol and rapid ultralow-temperature freezing.

Background Activated carbon is one of common adsorbents and has been widely applied to food hygiene, medical treatment, catalysis, nitrogen production by separating air, coke environment protection and the like.

Strong adsorbability of the activated carbon mainly depends on a large specific surface area, while research results of Fanmin Mei [2010], Guocheng Liu [2014], et al. have shown that selective adsorption to specific components, such as formaldehyde, carbon dioxide, chromium ions, lead ions and mercury ions, depends on a pore structure and surface functional groups of the activated carbon.

Fanmin Mei [2010], et al. have researched the effect of surface acid oxygen-containing functional groups on adsorption of the formaldehyde, and the results showed that phenolic hydroxyl groups can remarkably influence the effect of adsorbing the formaldehyde by the activated carbon.

Chinese invention patent CN201410713305.7 has disclosed a method of preparing activated carbon capable of eliminating formaldehyde by modifying activated carbon with a surfactant, then loading the modified activated carbon by a formaldehyde catching agent and then conducting a normal-temperature freeze drying loading method.

Chinese invention patent CN201610585039.3 has disclosed a method of preparing an activated carbon adsorbing material for removing medium-low concentration by the following steps of sequentially conducting grinding, acid pickling, washing and carbonization on walnut shells as raw materials, and sequentially conducting washing, drying, modification, ultrasonic combination, soaking, washing and drying on prepared activated carbon.

Chinese invention patent CN201610638618.X has disclosed a method for obtaining modified activated carbon by the following steps of oxidizing ferric chloride with potassium permanganate, modifying ferric sulphate, conducting ultrasonic oscillation and finally, conducting calcination.

The activated carbon prepared by the aforementioned methods has a certain adsorption effect to the formaldehyde; however, processes of some methods are complex, original processes of some methods need to be adjusted, and the direct cost or the indirect cost is high.

On the basis of the existing process, activated carbon capable of meeting specific functional demands is modified, so that a novel process with low cost and obvious effect becomes an imperious demand.

The paper of Hongyu Si [2016], as the inventor of the present invention, also has disclosed a method for obtaining activated carbon by conducting ultralow-temperature pre-treatment on coconut shells with liquid nitrogen, conducting activation with rapid heating and preparing the activated carbon at 800°C, wherein the specific surface area exceeds that of the activated carbon prepared without pre-treatment at 800°C and is increased from 1800m?/g to 2300m?/g or above, and a total micropore volume is also increased from 0.67cm3/g to 0.92cm?/g.

This method is proposed based on a principle that the destructive effect on the interior of a material structure with rapid heating exceeds that with a common heating mode, and low-temperature treatment belongs to pre-treatment on the raw materials.

Summary A purpose of the present invention is to provide a natural cooling process based on completion of activation of activated carbon.

Because part of pores are blocked by elastic polycondensation and gradual deposition of tar substances, a liquid nitrogen rapid freezing method or a freezing method with brine ice of -20°C or below is employed, and the pores are rapidly shaped at -150°C or below or -20°C or below and a deposit precursor is dissolved.

By employing a preparation method of modified activated carbon provided by the method, compared with activated carbon obtained by activation with a same concentration of phosphoric acid and natural air cooling, the prepared activated carbon has the advantages that phenolic hydroxyl groups and a specific surface area are both obviously increased and the energy saving effect is obvious.

The method is simple, and low in cost.

In order to achieve the purpose, a technical solution of the present invention is as follows: a method of preparing modified activated carbon with phenol and rapid ultralow-temperature freezing comprises the following steps: crushing dry shells, and weighing the crushed shells for standby; preparing a phosphoric acid solution, mixing the weighed shells with the phosphoric acid solution, and conducting still standing and impregnation for 2 h to obtain a mixture A; weighing phenol, mixing the phenol with the mixture A, and putting the mixture into a drying box at 105°C for drying for 12 h to obtain a mixture B; putting the mixture B into a ceramic reactor, introducing nitrogen firstly to clearly purge oxygen, and then turning on a heating switch of the ceramic reactor; raising a temperature of the ceramic reactor to an activation temperature, keeping the temperature for a period of time, and obtaining an activated material C after activation; after the activation time is stopped, rapidly sinking the activated material C in a vessel fully filled with the liquid nitrogen or the brine ice of -20°C or below for rapid cooling, rapidly sealing the vessel, and putting the vessel on an oscillator for oscillation for 2 h to obtain an activated material D; putting the activated material D into a washing vessel for repeatedly boiling with water until neutral; then adding a hydrochloric acid solution with a weight of 2%. of the weight of the activated material D and a mass fraction of 30%, conducting boiling with the water and acid pickling, and finally conducting boiling with the water and acid pickling again until neutral; and conducting drying to obtain an activated carbon product.

The technical solution further has the specific characteristic that the particle size of the crushed dry shells is 0.15-30.00 mm.

The mass fraction of the phosphoric acid solution is 25%-60%, and an impregnation ratio of the shells to the phosphoric acid solution (that is, a mass ratio of the shells to the phosphoric acid solution, similarly hereinafter) is (1 to 1)-(1 to 4). A weight of the phenol is equivalent to 1/20-1/3 of a weight of the mixture A.

The temperature of the ceramic reactor is raised to the activation temperature at a heating rate of 5°C-10°C/min, and the activation temperature is 300-1100 °C and kept unchanged for 0.5- 24 h.

The present invention has the beneficial effects that: by employing the activated carbon preparation method provided by the present invention, for the prepared activated carbon product, the wear resistance strength and the microporosity are equivalent to those of the activated carbon as the raw material, but the specific surface area is increased by 30%-150% compared with the activated carbon without being treated with the liquid nitrogen or the brine ice under the same conditions, a preparation temperature is lowered by 150-350°C, and the phenolic hydroxyl groups are increased by 30%-300%. Furthermore, the method is simple to operate and low in cost and has outstanding advantages at the places with a large cold energy balance, such as liquefied natural gas (LNG) vaporizing station.

Large content of the phenolic hydroxyl groups may meet the application demands on the specific conditions of adsorbing the formaldehyde and the like.

Detailed Description The present invention is further described below in combination with embodiments.

Embodiment 1 Dry shells were crushed until the particle size was 0.15-30.00 mm, and the crushed shells were weighed for standby.

A phosphoric acid solution was prepared with the mass fraction of 25%. The weighed shells were mixed with the phosphoric acid solution according to an impregnation ratio of 1 to 2, and still standing was conducted for 2 h to obtain a mixture A.

Phenol, a weight of which was equivalent to that of 1/10 of the mixture A, was weighed and mixed with the mixture A, and a mixture was put into a drying box at 105°C for drying for 12 h to obtain a mixture B.

The mixture B was put into a ceramic reactor, nitrogen was introduced firstly to clearly purge oxygen, and then a heating switch of the ceramic reactor was turned on.

The temperature of the ceramic reactor was raised to 600°C at a heating rate of 10°C/min and was kept for 2 h to obtain an activated material C.

After an activation time was stopped, the activated material C was rapidly sunken in a vessel fully filled with liquid nitrogen, and the vessel was rapidly sealed and then put on an oscillator for oscillation for 2 h to obtain an activated material D.

The activated material D was put into a washing vessel for repeated boiling with water until neutral.

Then a hydrochloric acid solution, a weight of which was 2%. of a weight of the activated material D, was added for boiling with the water and acid pickling, wherein the mass fraction of the hydrochloric acid solution was 30%. Finally, a product was boiled with the water and washed again until neutral, and the product was dried to obtain an activated carbon product.

After the activated carbon was obtained, a JW-BK132F model nitrogen absorption apparatus with a static volumetric method, manufactured by Beijing JWGB Sci & Tech Ltd., was used to determine a specific surface area of the product, and phenolic hydroxyl groups were determined with a Boehm titrimetry. Indexes of the activated carbon product were as follows: the specific surface area was 1327 m?/g, and the content of the phenolic hydroxyl groups was 4.28x 10° mol/g.

Embodiment 2 (reference example) Dry shells were crushed until the particle size was 0.15-30.00 mm, and the crushed shells were weighed for standby. A phosphoric acid solution was prepared with the mass fraction of 25%. The weighed shells were mixed with the phosphoric acid solution according to an impregnation ratio of 1 to 2, and still standing was conducted for 2 h to obtain a mixture A. Phenol, a weight of which was equivalent to that of 1/10 of the mixture A, was weighed and mixed with the mixture A, and a mixture was put into a drying box at 105°C for drying for 12 h to obtain a mixture B. The mixture B was put into a ceramic reactor, nitrogen was introduced firstly to clearly purge oxygen, and then a heating switch of the ceramic reactor was turned on. The temperature of the ceramic reactor was raised to 600°C at a heating rate of 10°C/min and was kept for 2 h to obtain an activated material C. After an activation time was stopped, the activated material C was rapidly sunken in a vessel fully filled with brine ice of -20°C, and the vessel was rapidly sealed and then put on an oscillator for oscillation for 2 h to obtain an activated material D. The activated material D was put into a washing vessel for repeated boiling with water until neutral. Then a hydrochloric acid solution, a weight of which was 2/1000 of a weight of the activated material D, was added for boiling with the water and acid pickling, wherein the mass fraction of the hydrochloric acid solution was 30%. Finally, a product was boiled with the water and washed again until neutral, and the product was dried to obtain an activated carbon product.

After the activated carbon was obtained, a JW-BK132F model nitrogen absorption apparatus with a static volumetric method, manufactured by Beijing JWGB Sci & Tech Ltd., was used to determine a specific surface area of the product, and phenolic hydroxyl groups were determined with a Boehm titrimetry. Indexes of the activated carbon product were as follows: the specific surface area was 933 m?/g, and the content of the phenolic hydroxyl groups was 1.11x 10 mol/g.

Embodiment 3 (reference example) Dry shells were crushed until the particle size was 0.15-30.00 mm, and the crushed shells were weighed for standby. A phosphoric acid solution was prepared with the mass fraction of 25%. The weighed shells were mixed with the phosphoric acid solution according to an impregnation ratio of 1 to 2, and still standing was conducted for 2 h to obtain a mixture A. Phenol, a weight of which was equivalent to that of 1/10 of the mixture A, was weighed and mixed with the mixture A, and a mixture was put into a drying box at 105°C for drying for 12 h to obtain a mixture B.

The mixture B was put into a ceramic reactor, nitrogen was introduced firstly to clearly purge oxygen, and then a heating switch of the ceramic reactor was turned on.

The temperature of the ceramic reactor was raised to 600°C at a heating rate of 10°C/min and was kept for 2 h to 5 obtain an activated material C.

After an activation time was stopped, the heating switch of the ceramic reactor was turned off, natural cooling was conducted until the temperature of the activated material C reached a room temperature, and then nitrogen was closed to obtain an activated material D.

The activated material D was put into a washing vessel for repeated boiling with water until neutral.

Then a hydrochloric acid solution, a weight of which was 2% of a weight of the activated material D, was added for boiling with the water and acid pickling, wherein the mass fraction of the hydrochloric acid solution was 30%. Finally, a product was boiled with the water and washed again until neutral, and the product was dried to obtain an activated carbon product.

After the activated carbon was obtained, a JW-BK132F model nitrogen absorption apparatus with a static volumetric method, manufactured by Beijing JWGB Sci & Tech Ltd., was used to determine a specific surface area of the product, and phenolic hydroxyl groups were determined with a Boehm titrimetry.

Indexes of the activated carbon product were as follows: the specific surface area was 673 m?/g, and the content of the phenolic hydroxyl groups was 0.35x 1073 mol/g.

Embodiment 4 Dry shells were crushed until the particle size was 0.15-30.00 mm, and the crushed shells were weighed for standby.

A phosphoric acid solution was prepared with the mass fraction of 60%. The weighed shells were mixed with the phosphoric acid solution according to an impregnation ratio of 1 to 2, and still standing was conducted for 2 h to obtain a mixture A.

Phenol, a weight of which was equivalent to that of 1/10 of the mixture A, was weighed and mixed with the mixture A, and a mixture was put into a drying box at 105°C for drying for 12 h to obtain a mixture B.

The mixture B was put into a ceramic reactor, nitrogen was introduced firstly to clearly purge oxygen, and then a heating switch of the ceramic reactor was turned on.

The temperature of the ceramic reactor was raised to 300°C at a heating rate of 10°C/min and was kept for 24 h to obtain an activated material C.

After an activation time was stopped, the activated material C was rapidly sunken in a vessel fully filled with liquid nitrogen, and the vessel was rapidly sealed and then put on an oscillator for oscillation for 2 h to obtain an activated material D.

The activated material D was put into a washing vessel for repeated boiling with water until neutral.

Then a hydrochloric acid solution, a weight of which was 2% of a weight of the activated material D, was added for boiling with the water and acid pickling, wherein the mass fraction of the hydrochloric acid solution was 30%. Finally, a product was boiled with the water and washed again until neutral, and the product was dried to obtain an activated carbon product.

After the activated carbon was obtained, a JW-BK132F model nitrogen absorption apparatus with a static volumetric method, manufactured by Beijing JWGB Sci & Tech Ltd., was used to determine a specific surface area of the product, and phenolic hydroxyl groups were determined with a Boehm titrimetry. Indexes of the activated carbon product were as follows: the specific surface area was 1112 m?/g, and the content of the phenolic hydroxyl groups was 38.23x 103 mol/g.

Embodiment 5 (reference example) Dry shells were crushed until the particle size was 0.15-30.00 mm, and the crushed shells were weighed for standby. A phosphoric acid solution was prepared with the mass fraction of 60%. The weighed shells were mixed with the phosphoric acid solution according to an impregnation ratio of 1 to 2, and still standing was conducted for 2 h to obtain a mixture A. Phenol, a weight of which was equivalent to that of 1/10 of the mixture A, was weighed and mixed with the mixture A, and a mixture was put into a drying box at 105°C for drying for 12 h to obtain a mixture B. The mixture B was put into a ceramic reactor, nitrogen was introduced firstly to clearly purge oxygen, and then a heating switch of the ceramic reactor was turned on. The temperature of the ceramic reactor was raised to 300°C at a heating rate of 10°C/min and was kept for 24 h to obtain an activated material C. After an activation time was stopped, the activated material C was rapidly sunken in a vessel fully filled with brine ice of -20°C, and the vessel was rapidly sealed and then put on an oscillator for oscillation for 2 h to obtain an activated material D. The activated material D was put into a washing vessel for repeated boiling with water until neutral. Then a hydrochloric acid solution, a weight of which was 2%. of a weight of the activated material D, was added for boiling with the water and acid pickling, wherein the mass fraction of the hydrochloric acid solution was 30%. Finally, a product was boiled with the water and washed again until neutral, and the product was dried to obtain an activated carbon product.

After the activated carbon was obtained, a JW-BK132F model nitrogen absorption apparatus with a static volumetric method, manufactured by Beijing JWGB Sci & Tech Ltd., was used to determine a specific surface area of the product, and phenolic hydroxyl groups were determined with a Boehm titrimetry. Indexes of the activated carbon product were as follows: the specific surface area was 765 m?/g, and the content of the phenolic hydroxyl groups was 9.84x10 mol/g.

Embodiment 6 (reference example) Dry shells were crushed until the particle size was 0.15-30.00 mm, and the crushed shells were weighed for standby. A phosphoric acid solution was prepared with the mass fraction of 60%. The weighed shells were mixed with the phosphoric acid solution according to an impregnation ratio of 1 to 2, and still standing was conducted for 2 h to obtain a mixture A. Phenol, a weight of which was equivalent to that of 1/10 of the mixture A, was weighed and mixed with the mixture A, and a mixture was put into a drying box at 105°C for drying for 12 h to obtain a mixture B.

The mixture B was put into a ceramic reactor, nitrogen was introduced firstly to clearly purge oxygen, and then a heating switch of the ceramic reactor was turned on.

The temperature of the ceramic reactor was raised to 300°C at a heating rate of 10°C/min and was kept for 24 h to obtain an activated material C.

After an activation time was stopped, the heating switch of the ceramic reactor was turned off, natural cooling was conducted until the temperature of the activated material C reached a room temperature, and then nitrogen was closed to obtain an activated material D.

The activated material D was put into a washing vessel for repeated boiling with water until neutral.

Then a hydrochloric acid solution, a weight of which was 2%. of a weight of the activated material D, was added for boiling with the water and acid pickling, wherein the mass fraction of the hydrochloric acid solution was 30%. Finally, a product was boiled with the water and washed again until neutral, and the product was dried to obtain an activated carbon product.

After the activated carbon was obtained, a JW-BK132F model nitrogen absorption apparatus with a static volumetric method, manufactured by Beijing JWGB Sci & Tech Ltd., was used to determine a specific surface area of the product, and phenolic hydroxyl groups were determined with a Boehm titrimetry.

Indexes of the activated carbon product were as follows: the specific surface area was 222 m?/g, and the content of the phenolic hydroxyl groups was 0.25x 1073 mol/g.

Embodiment 7 Dry shells were crushed until the particle size was 0.15-30.00 mm, and the crushed shells were weighed for standby.

A phosphoric acid solution was prepared with the mass fraction of 45%. The weighed shells were mixed with the phosphoric acid solution according to an impregnation ratio of 1 to 4, and still standing was conducted for 2 h to obtain a mixture A.

Phenol, a weight of which was equivalent to that of 1/3 of the mixture A, was weighed and mixed with the mixture A, and a mixture was put into a drying box at 105°C for drying for 12 h to obtain a mixture B.

The mixture B was put into a ceramic reactor, nitrogen was introduced firstly to clearly purge oxygen, and then a heating switch of the ceramic reactor was turned on.

The temperature of the ceramic reactor was raised to 350°C at a heating rate of 10°C/min and was kept for 24 h to obtain an activated material C.

After an activation time was stopped, the activated material C was rapidly sunken in a vessel fully filled with liquid nitrogen, and the vessel was rapidly sealed and then put on an oscillator for oscillation for 2 h to obtain an activated material D.

The activated material D was put into a washing vessel for repeated boiling with water until neutral.

Then a hydrochloric acid solution, a weight of which was 2%. of a weight of the activated material D, was added for boiling with the water and acid pickling, wherein the mass fraction of the hydrochloric acid solution was 30%. Finally, a product was boiled with the water and washed again until neutral, and the product was dried to obtain an activated carbon product.

After the activated carbon was obtained, a JW-BK132F model nitrogen absorption apparatus with a static volumetric method, manufactured by Beijing JWGB Sci & Tech Ltd., was used to determine a specific surface area of the product, and phenolic hydroxyl groups were determined with a Boehm titrimetry. Indexes of the activated carbon product were as follows: the specific surface area was 2512 m?/g, and the content of the phenolic hydroxyl groups was 24.77x10°3 mol/g.

Embodiment 8 (reference example) Dry shells were crushed until the particle size was 0.15-30.00 mm, and the crushed shells were weighed for standby. A phosphoric acid solution was prepared with the mass fraction of 45%. The weighed shells were mixed with the phosphoric acid solution according to an impregnation ratio of 1 to 4, and still standing was conducted for 2 h to obtain a mixture A. Phenol, a weight of which was equivalent to that of 1/3 of the mixture A, was weighed and mixed with the mixture A, and a mixture was put into a drying box at 105°C for drying for 12 h to obtain a mixture B. The mixture B was put into a ceramic reactor, nitrogen was introduced firstly to clearly purge oxygen, and then a heating switch of the ceramic reactor was turned on. The temperature of the ceramic reactor was raised to 350°C at a heating rate of 10°C/min and was kept for 24 h to obtain an activated material C. After an activation time was stopped, the activated material C was rapidly sunken in a vessel fully filled with brine ice of -20°C, and the vessel was rapidly sealed and then put on an oscillator for oscillation for 2 h to obtain an activated material D. The activated material D was put into a washing vessel for repeated boiling with water until neutral. Then a hydrochloric acid solution, a weight of which was 2%. of a weight of the activated material D, was added for boiling with the water and acid pickling, wherein the mass fraction of the hydrochloric acid solution was 30%. Finally, a product was boiled with the water and washed again until neutral, and the product was dried to obtain an activated carbon product.

After the activated carbon was obtained, a JW-BK132F model nitrogen absorption apparatus with a static volumetric method, manufactured by Beijing JWGB Sci & Tech Ltd., was used to determine a specific surface area of the product, and phenolic hydroxyl groups were determined with a Boehm titrimetry. Indexes of the activated carbon product were as follows: the specific surface area was 1395 m?/g, and the content of the phenolic hydroxyl groups was 45.39x10°3 mol/g.

Embodiment 9 (reference example) Dry shells were crushed until the particle size was 0.15-30.00 mm, and the crushed shells were weighed for standby. A phosphoric acid solution was prepared with the mass fraction of 45%. The weighed shells were mixed with the phosphoric acid solution according to an impregnation ratio of 1 to 4, and still standing was conducted for 2 h to obtain a mixture A. Phenol, a weight of which was equivalent to that of 1/3 of the mixture A, was weighed and mixed with the mixture A, and a mixture was put into a drying box at 105°C for drying for 12 h to obtain a mixture B. The mixture B was put into a ceramic reactor, nitrogen was introduced firstly to clearly purge oxygen, and then a heating switch of the ceramic reactor was turned on.

The temperature of the ceramic reactor was raised to 350°C at a heating rate of 10°C/min and was kept for 24 h to obtain an activated material C.

After an activation time was stopped, the heating switch of the ceramic reactor was turned off, natural cooling was conducted until the temperature of the activated material C reached a room temperature, and then nitrogen was closed to obtain an activated material D.

The activated material D was put into a washing vessel for repeated boiling with water until neutral.

Then a hydrochloric acid solution, a weight of which was 2%. of a weight of the activated material D, was added for boiling with the water and acid pickling, wherein the mass fraction of the hydrochloric acid solution was 30%. Finally, a product was boiled with the water and washed again until neutral, and the product was dried to obtain an activated carbon product.

After the activated carbon was obtained, a JW-BK132F model nitrogen absorption apparatus with a static volumetric method, manufactured by Beijing JWGB Sci & Tech Ltd., was used to determine a specific surface area of the product, and phenolic hydroxyl groups were determined with a Boehm titrimetry.

Indexes of the activated carbon product were as follows: the specific surface area was 351 m?/g, and the content of the phenolic hydroxyl groups was 1.32x 103 mol/g.

Embodiment 10

Dry shells were crushed until the particle size was 0.15-30.00 mm, and the crushed shells were weighed for standby.

A phosphoric acid solution was prepared with the mass fraction of 45%. The weighed shells were mixed with the phosphoric acid solution according to an impregnation ratio of 1 to 3, and still standing was conducted for 2 h to obtain a mixture A.

Phenol, a weight of which was equivalent to that of 1/5 of the mixture A, was weighed and mixed with the mixture A, and a mixture was put into a drying box at 105°C for drying for 12 h to obtain a mixture B.

The mixture B was put into a ceramic reactor, nitrogen was introduced firstly to clearly purge oxygen, and then a heating switch of the ceramic reactor was turned on.

The temperature of the ceramic reactor was raised to 1100°C at a heating rate of 10°C/min and was kept for 0.5 h to obtain an activated material C.

After an activation time was stopped, the activated material C was rapidly sunken in a vessel fully filled with liquid nitrogen, and the vessel was rapidly sealed and then put on an oscillator for oscillation for 2 h to obtain an activated material D.

The activated material D was put into a washing vessel for repeated boiling with water until neutral.

Then a hydrochloric acid solution, a weight of which was 2%. of a weight of the activated material D, was added for boiling with the water and acid pickling, wherein the mass fraction of the hydrochloric acid solution was 30%. Finally, a product was boiled with the water and washed again until neutral, and the product was dried to obtain an activated carbon product.

After the activated carbon was obtained, a JW-BK132F model nitrogen absorption apparatus with a static volumetric method, manufactured by Beijing JWGB Sci & Tech Ltd., was used to determine a specific surface area of the product, and phenolic hydroxyl groups were determined with a Boehm titrimetry. Indexes of the activated carbon product were as follows: the specific surface area was 1724 m?/g, and the content of the phenolic hydroxyl groups was 0.25% 103 mol/g.

Embodiment 11 (reference example) Dry shells were crushed until the particle size was 0.15-30.00 mm, and the crushed shells were weighed for standby. A phosphoric acid solution was prepared with the mass fraction of 45%. The weighed shells were mixed with the phosphoric acid solution according to an impregnation ratio of 1 to 3, and still standing was conducted for 2 h to obtain a mixture A. Phenol, a weight of which was equivalent to that of 1/5 of the mixture A, was weighed and mixed with the mixture A, and a mixture was put into a drying box at 105°C for drying for 12 h to obtain a mixture B. The mixture B was put into a ceramic reactor, nitrogen was introduced firstly to clearly purge oxygen, and then a heating switch of the ceramic reactor was turned on. The temperature of the ceramic reactor was raised to 1100°C at a heating rate of 10°C/min and was kept for 0.5 h to obtain an activated material C. After an activation time was stopped, the activated material C was rapidly sunken in a vessel fully filled with brine ice of -20°C, and the vessel was rapidly sealed and then put on an oscillator for oscillation for 2 h to obtain an activated material D. The activated material D was put into a washing vessel for repeated boiling with water until neutral. Then a hydrochloric acid solution, a weight of which was 2% of a weight of the activated material D, was added for boiling with the water and acid pickling, wherein the mass fraction of the hydrochloric acid solution was 30%. Finally, a product was boiled with the water and washed again until neutral, and the product was dried to obtain an activated carbon product.

After the activated carbon was obtained, a JW-BK132F model nitrogen absorption apparatus with a static volumetric method, manufactured by Beijing JWGB Sci & Tech Ltd., was used to determine a specific surface area of the product, and phenolic hydroxyl groups were determined with a Boehm titrimetry. Indexes of the activated carbon product were as follows: the specific surface area was 1185 m?/g, and the content of the phenolic hydroxyl groups was 1.38x 10° mol/g.

Embodiment 12 (reference example) Dry shells were crushed until the particle size was 0.15-30.00 mm, and the crushed shells were weighed for standby. A phosphoric acid solution was prepared with the mass fraction of 45%. The weighed shells were mixed with the phosphoric acid solution according to an impregnation ratio of 1 to 3, and still standing was conducted for 2 h to obtain a mixture A. Phenol, a weight of which was equivalent to that of 1/5 of the mixture A, was weighed and mixed with the mixture A, and a mixture was put into a drying box at 105°C for drying for 12 h to obtain a mixture B. The mixture B was put into a ceramic reactor, nitrogen was introduced firstly to clearly purge oxygen, and then a heating switch of the ceramic reactor was turned on. The temperature of the ceramic reactor was raised to 1100°C at a heating rate of 10°C/min and was kept for 0.5 h to obtain an activated material C. After an activation time was stopped, the heating switch of the ceramic reactor was turned off, natural cooling was conducted until the temperature of the activated material C reached a room temperature, and then nitrogen was closed to obtain an activated material D.

The activated material D was put into a washing vessel for repeated boiling with water until neutral.

Then a hydrochloric acid solution, a weight of which was 2%. of a weight of the activated material D, was added for boiling with the water and acid pickling, wherein the mass fraction of the hydrochloric acid solution was 30%. Finally, a product was boiled with the water and washed again until neutral, and the product was dried to obtain an activated carbon product.

After the activated carbon was obtained, a JW-BK132F model nitrogen absorption apparatus with a static volumetric method, manufactured by Beijing JWGB Sci & Tech Ltd., was used to determine a specific surface area of the product, and phenolic hydroxyl groups were determined with a Boehm titrimetry.

Indexes of the activated carbon product were as follows: the specific surface area was 549 m?/g, and the content of the phenolic hydroxyl groups was 0.04x 1073 mol/g.

Claims (5)

CONCLUSIONS A process for preparing modified activated carbon with phenol and ultra-low temperature rapid freezing, the process comprising the steps of: — crushing dry shells, and weighing the crushed shells to prepare them; — preparing a phosphoric acid solution, mixing the weighed shells with the phosphoric acid solution, and impregnating by standing for 2 hours to obtain a mixture A; — weighing phenol, mixing phenol with mixture A, and placing the mixture in a drying cabinet at 105°C to dry for 12 hours to obtain mixture B; - placing the mixture B in a ceramic reactor, introducing nitrogen to remove the oxygen, and then turning on a heating switch of the ceramic reactor; - increasing the temperature of the ceramic reactor to an activation temperature, maintaining the temperature for a certain time, and obtaining an activated material C after activation; — after the activation time has elapsed, rapidly settling the activated material C in a vessel completely filled with liquid nitrogen or brine ice at -20°C or below for rapid cooling, quickly sealing the vessel and placing it on an oscillator placing the vessel for oscillation for 2 hours to obtain an activated material D; - placing the activated material D in a washing vessel to repeatedly boil it with water until it is neutral; — then adding a hydrochloric acid solution weighing 2%. by weight of the activated material D and a mass fraction of 30%, boiling with the water and acid, and finally boiling again with water and acid until neutral, and drying to obtain an activated carbon product. The process for preparing modified activated carbon with phenol and ultra-low temperature flash freezing according to claim 1, wherein the particle size of the crushed dry shells is 0.15 - 30.00 mm. The process for preparing modified activated carbon with phenol and ultra-low temperature rapid freezing according to claim 1, wherein the mass fraction of the phosphoric acid solution is 25% - 60%, and an impregnation ratio of the shells to the phosphoric acid solution (1 to 1) - (1 to 4). The process for preparing modified activated carbon with phenol and ultra-low temperature flash freezing according to claim 1, wherein the weight of the phenol is equal to 1/20 - 1/3 of the weight of the mixture A. The process for producing modified activated carbon with phenol and ultra-low temperature rapid freezing according to claim 1, wherein the temperature of the ceramic reactor is increased to the activation temperature at a heating rate of 5°C - 10°C/min, and the activation temperature is 300-1100°C and is kept unchanged for 0.5-24 hours.