RU2023661C1 - Method of activated carbon producing - Google Patents

Abstract

FIELD: chemical technology. SUBSTANCE: carbon-containing material is carbonized at 400-600 C, heated without gaseous reagents up to 800-850 C at the rate of temperature increase 50-100 C/h, activated by steam at the mass ratio of carbon-containing material and steam = 1:5-10 and milled. EFFECT: improved method of activated carbon making. 1 tbl

Description

 The invention relates to the production of powdered activated carbon (a.u.) with increased adsorption capacity for high molecular weight organic compounds.

A method of producing activated carbon which comprises treating raw charcoal (main fraction 2-5 mm) in air at 280-420 ^{° C,} subsequent cooling ^to 40 ° C and the activation by steam at 800-900 ^{° C} at a rate of 3 kg of steam per 1 kg of raw coal, the total yield of the finished product from the feedstock is 18-20 wt.% (ed. St. USSR N 1401277, 1988).

The disadvantage of this method is the complexity of the process and high requirements and fire safety, since at 200 ^about With possible spontaneous combustion of raw coal in air.

The closest to the proposed technical essence and the achieved result is a method of producing powdered activated carbon, including grinding coal to a particle size of less than 0.5 mm, and heating to 1000-1200 ^about With subsequent activation at this temperature in a vortex furnace with an activating agent, containing water vapor (ed. St. USSR N 1567515, 1990).

 The disadvantage of this method is the low adsorption capacity of the resulting a. at. for high molecular weight organic compounds in the liquid phase, as well as a low overall yield of the finished product (20-23%).

 The aim of the invention is to increase the adsorption capacity of the resulting activated carbon for high molecular weight organic compounds in the liquid phase and increase the overall yield of the finished product.

The goal is achieved by a method comprising the carbonization of the carbonaceous material at 400-650 ^{° C,} heating the carbonized product without access of gaseous reactants to 800-850 ^{° C} with a temperature elevation rate of ^about 50-100 C / hr and activation with steam at a weight ratio of the carbonized product and water vapor 1: 5-10, and after activation, grinding of coal is carried out.

 The essence of the proposed method is as follows.

 The stage of heating the carbonized product to an activation temperature is crucial for the formation of the a.u. and therefore its adsorption properties. Numerous experiments have shown that in order to obtain the necessary porous structure, it is important both to withstand at this stage a certain rate of temperature rise and to prevent the presence of oxidizing gaseous reagents.

 For efficient adsorption of high molecular weight organic compounds from the liquid phase, it is important to achieve the development of the maximum volume of large micropores in the adsorbent with a width of 2-3 mm. It has been experimentally established that during the activation process, the efficient opening of micropore nuclei occurs at a certain ratio of carbonized product to water vapor. With a decrease in the amount of water vapor, the stoichiometry of the carbon oxidation reaction is violated, and with an increase in it, surface burning of particles occurs, which reduces the adsorption properties of the a.u. and product yield.

 The implementation of particle grinding a.u. after activation, it allows to increase the adsorption properties and yield of the finished product. On the other hand, upon activation of a powdery carbon-containing material, small particles generally burn out rather than activate.

 The method is as follows.

Take carbonaceous material (wood, lignin, tsellolignin, coal, char, etc.) or formed from these pellets and carbonation is carried out in the reactor or in a rotary kiln with a temperature elevation rate of 15-40 ^C / min to ^about 400-650 C in an atmosphere of carbon dioxide or flue gases.

Conducting carbonization at a temperature below 400 ^{° C} does not ensure removal of all volatiles amount that gives the formation of microporous structure when activated coal. On the other hand, when carbonizing temperature above 650 ^{° C} does not provide the necessary structure of the carbonized product.

Then, the carbonized product was discharged, cooled, fed to another reactor or furnace, and heating is carried out without access of gaseous reactants to 800-850 ^{° C} with a temperature elevation rate of ^about 50-100 C / hr.

Heating the product in the second stage below 800 ^{° C} does not lead to formation of a large amount of the microcrystalline carbon, which ensures the development of a large micropore volume.

Heating above 850 ^{° C} leads to the formation of large crystallites and carbon develop low micropore volume.

After completion of the heating operation is performed without cooling the product of its activation, for which start fed to the reactor (furnace) steam at a ratio of water vapor to coal 5-10: 1, while establishing the temperature ^of 850-950 C at which the activation process and lead. Activation at temperatures below 850 ^{° C} is characterized by low rate of carbon oxidation reactions. At the same time the activation at a temperature above 950 ^{° C} is accompanied by surface ablation and coal ashing.

 Upon reaching a certain total pore volume of coal (controlled by moisture capacity), it is discharged from the reactor (furnace) and cooled to room temperature. Then carry out the grinding of active particles (granules) in a mill of any type to particle sizes less than 100 microns.

-

-) с молекулярной массой 20000, равную 127-152 мг/г и по диизопропиловому эфиру фторфосфорной кислоты. (СН₃)₂-СНО-Р= 0 с молекулярной массой 184, равную (СН₃)₂-СНО 215-237 мг/г. Общий выход готового продукта составил 30-35 мас.%.Powdered activated carbon obtained in this way has an adsorption capacity for polyethylene glycol (-

-

-) with a molecular weight of 20,000, equal to 127-152 mg / g and diisopropyl ether of phosphoric acid. (CH ₃ ) ₂ —CHO — P = 0 with a molecular weight of 184 equal to (CH ₃ ) ₂ —CHO 215–237 mg / g. The total yield of the finished product was 30-35 wt.%.

PRI me R 1. Take 10 kg of coal tar granules obtained by molding a paste consisting of 6.5 kg of crushed coal grade SS and 3.5 kg of prepared wood chemical resin and carry out their carbonization at a rate of temperature rise of 30 ^about C / min to a temperature ^of 500 C in a carbon dioxide atmosphere, a flow rate of 12 l / min. Then, the carbonized product was discharged, cooled to room temperature and fed into an electric furnace where it is heated without access of gaseous reactants to ^about 850 C at a temperature elevation rate of 100 ^C / h. After completion of the activation heating is carried out, which is fed to the electric furnace at a ratio of steam heated product to steam 1:10, and the temperature was raised to 900 ° ^C. The activation is carried out to achieve a total pore volume of 1.0 cm ³ / g. Then the activated carbon is discharged from the electric furnace, cooled to room temperature and ground in a ball mill to particle sizes less than 100 microns.

 The obtained powdered activated carbon has an adsorption capacity of 143 mg / g for polyethylene glycol and 222 mg / g for diisopropyl ether of fluorophosphoric acid. The total yield of the finished product was 33.4%.

EXAMPLE 2. EXAMPLE birch wood is carbonized at a temperature rise rate of 30 ^C / min to T = 550 ^o C; yield 30 wt.%.

Take 10 kg birch raw coal and carry it into the heating furnace without access of gaseous reactants at a rate of temperature rise of 50 ^C / min to a temperature of 800 ° ^C. After completion of the activation heating is carried out at a temperature of 900 ^C and a ratio of the heated product to water vapor 1 : 5 until a total pore volume of 1.6 cm ³ / g is reached. Then the activated carbon is discharged from the electric furnace, cooled to room temperature and ground in a ball mill to particle sizes less than 100 microns.

 The obtained powdered activated carbon has a polyethylene glycol adsorption capacity of 129 mg / g and a fluorophosphoric acid diisopropyl ester of 218 mg / g. The total yield of the finished product was 29.1%.

EXAMPLE 3. EXAMPLE Tselloligninovye granules are carbonized at a temperature rise rate of 50 ^C / min to T = 600 ^{° C;} yield 26%.

Take 10kg tselloligninovyh carbonized granules is carried out in an electric heating them without access of gaseous reactants at a rate of temperature rise of ^{70 °} C / hr to a temperature of 820 ° ^C. After completion of the activation heating is carried out at a temperature of 870 ^C and a ratio of the heated product to steam of 1: 7 to achieve a total pore volume of 1.2 cm ³ / g Then the activated carbon is discharged from the electric furnace, cooled to room temperature and ground in a ball mill to particle sizes less than 100 microns.

 The obtained powdered activated carbon has an adsorption capacity of 137 mg / g for polyethylene glycol and 232 mg / g for diisopropyl ester of fluorophosphoric acid. The total yield of the finished product amounted to 31.7%.

 The table presents examples 4-13, obtained analogously to the example on the influence of heating and activation modes on the adsorption capacity and overall yield of powdered activated carbon.

Test conditions: concentration in water: polyethylene glycol 120 mg / l; phosphoric acid diisopropyl ester 200 mg / g; temperature 20 ^o C.

As follows from the data obtained, when heated at a rate of temperature rise of 50-100 ^о С / h to a temperature of 800-850 ^о С without access of gaseous reagents and activation with a mass ratio of carbonized product and water vapor equal to 1: 5-10, followed by grinding of the finished product achieves an increase in the adsorption capacity in the liquid phase by 7-50% upon extraction of high molecular weight organic compounds and a simultaneous increase in the total yield of the finished product by 10-15%.

When the temperature rise rate of lower than 50 ^{° C} / h - formed fine micropores with a size of less than 0.5 mm, and when the lifting speed above 100 ° ^C / hr formed mainly transport pores, which reduces the adsorption capacity for large molecules.

 On the other hand, when the mass ratio of the heated product and water vapor is 1: 4, the porous structure is not fully opened, and when the mass ratio is 1:11, intense surface burning occurs, which also worsens the properties of the powdery a.u. during sorption from solutions and its output.

Claims (1)

METHOD FOR PRODUCING ACTIVE COAL, including grinding a carbon-containing material, heating and activating with an agent containing water vapor, characterized in that before heating, carbonization is carried out at 400 - 600 ^o С, heating is carried out without access of gaseous reagents to 800 - 850 ^o С at a rate of temperature rise 50 - 100 ^o C / h, and activation with water vapor at a mass ratio of carbon-containing material and water vapor 1: 5 - 10, and grinding is carried out after activation.

Images