PT106637B - PROCESS OF PRODUCTION OF ACTIVATED CHARCOAL FROM CORK MATERIAL - Google Patents

Abstract

The present invention relates to a process for the production of activated charcoal from cork material by physical activation. The process of the invention comprises a first step of pre-activating the cork material in an atmosphere comprising a water vapor at a temperature of 350 to 400 ° C for a period of time of 15 to 50 minutes; AND A SECOND STEP OF PYROLYSIS / ACTIVATION OF THE PRODUCT OBTAINED IN THE PRE-ACTIVATION STEP IN AN ATMOSPHERE CONSISTING IN NITROGEN AND STEAM WATER, AT A TEMPERATURE OF ABOUT 750 TO 850 ° C, FOR A PERIOD OF TIME OF 30 TO 90 MINUTES, BEING THAT THE TWO STEPS CAN BE PERFORMED CONSECUTIVELY IN THE SAME EQUIPMENT OR IN DIFFERENT MOMENTS AND EQUIPMENT.

Description

ABSTRACT

COAL PRODUCTION PROCESS ACTIVATED FROM CORK MATERIAL

The present invention relates to a process of producing activated carbon from cork material by physical activation. The process of the invention comprises a first step of pre-activating the cork material in an atmosphere comprising water vapor at a temperature of 350 to 400 ° C for a period of 15 to 50 minutes; and a second pyrolysis / activation step of the product obtained in the pre-activation step, in an atmosphere consisting of nitrogen and water vapor, at a temperature of about 750 to 850 ° C for a period of 30 to 90 minutes. The two steps can be performed consecutively on the same equipment or at different times and equipment.

DESCRIPTION

COAL PRODUCTION PROCESS ACTIVATED FROM CORK MATERIAL

FIELD OF INVENTION

The present invention relates to a process of producing activated charcoal from cork materials using physical activation.

BACKGROUND OF THE INVENTION

Activated carbons are porous solids, the adsorbent materials having older applications. Its application has been increasing in recent years, especially in areas related to environmental protection.

Due to their versatility, namely their porous structure, surface chemistry and shape, activated charcoals are used in different areas such as water treatment, wastewater decontamination, gas separation and storage, food and pharmaceutical industry, medicine, petrochemicals. , production of semiconductors or in catalytic processes.

Activated carbons may be prepared from carbon-rich and preferably low ash raw materials. However, since the production process involves the controlled burning of the carbonaceous structure of a precursor, resulting in high mass loss and generally low preparation yield (as low as 5 to 10% for prepared coals). from wood), the use of a low cost starting material has economic advantages.

There are two distinct techniques for producing activated carbon: chemical activation and physical activation.

The chemical activation technique consists of impregnating the selected raw material with chemicals, for example solutions of phosphoric acid, zinc chloride, sodium hydroxide or potassium hydroxide, after which a pyrolysis step is carried out at temperatures generally between 450 and 900 ° C and finally a wash to remove excess chemical followed by drying. This technique is not within the scope of the present invention.

The physical activation technique is traditionally composed of two steps, a first pyrolysis step, which consists of thermally degrading the carbonaceous structure of the raw material in an inert atmosphere and a second activation step, which consists of exposing the carbonized material to gases containing combined oxygen, such as water vapor or carbon dioxide. The two steps may be conducted sequentially on the same or separate equipment and the process may be carried out continuously or discontinuously.

Thus, for example, EP 1289883 Bl, entitled Method for the Production of Molded Activated Charcoal, relates to a continuous process for the production of cast activated carbon in which the raw material is continuously fed into the form of pellets. an indirectly heated rotary kiln divided into a pyrolysis zone and an activation zone with the addition of water vapor to the inert gas stream. The temperature of the product in the pyrolysis zone is about 850-900 ° C and the residence time is 120 to 180 minutes, while the temperature of the product in the activation zone is 910-920 ° C and the residence time of 480-720 minutes.

The production of activated charcoal by physical activation from various raw materials is also documented.

For example, RU 2138442, entitled Method of Production of Activated Carbon, discloses a process of producing charcoal based on charcoal; RU 2104925 entitled Method for Production of Activated Coai, discloses a process of producing activated carbon from plant raw materials and utility model CN 201109713, entitled Environment protection, energy saving, high effect shell active carbon activation furnace, presents the constructive aspects of a reactor for the production of activated carbon by a pyrolysis process and activation with water vapor using fruit peels as raw material.

Also the patent PT 103520, Processes for the production of activated charcoal from a lignocellulosic precursor, discloses a process for the production of activated charcoal from a coffee industry residue, using inert atmosphere carbonization and activation in a carbon atmosphere. carbon dioxide or water vapor.

There are also references to processes in which pyrolysis and activation are performed in a single step, such as:

Production of Activated Carbon from Palm-Oil Shell by Pyrolysis and Steam Activation in a Fixed Bed Reactor (ScienceAsia 25 (1999): 211-222) studies the production of activated charcoal from palm bark in a single step by performing pyrolysis and water vapor activation at temperatures ranging from 600 to 700 ° C within a period of 1 to 3 hours;

Evolution of the Active Surface of Carbons Produced from Various Raw Materials by Steam Pyrolisys / Activation (Chem Tech. Biotechnol 58 (1993): 321-330) discloses a one-step activated carbon production process, in this case using shell. of coconut as raw material.

None of the documents referred to above or suggest The use of materials of cork as raw material press to The charcoal production activated. The publication Cork: one new perspective (Magazine in Agrarian Sciences 30 (2007 ): 282 - 289), does reference The

production of activated charcoal from cork, either by physical activation with carbon dioxide or water vapor or by chemical activation with different chemical agents (sodium hydroxide, potassium hydroxide or phosphoric acid).

The physical activation process employed comprises two steps, a first pyrolysis step in a nitrogen atmosphere at temperatures ranging from 600 to 800 ° C for minutes and a second activation step at the same temperature using water vapor or carbon dioxide as an activating agent for an unspecified period of time. The use of water vapor as activating agent and a temperature of 750 ° C enabled an activated carbon with a specific apparent area of 660 m ^{2 to be obtained} . g ” ¹ and a total porous volume around 0.35 cm ³ . g ” ¹ .

This process results in an acceptable quality activated carbon, albeit with a low quality / cost ratio.

Accordingly, there is a need for an activated charcoal production process, not only from cork but also from less noble materials derived from it, resulting from cork's forest production chain and industrial transformation, to obtain high quality activated carbon through a more energy efficient process at a lower cost.

Surprisingly, it has been found that the process of the present invention not only provides activated charcoals with superior physical properties than those disclosed in the prior art documents with cork as a raw material (as shown below), but still results in a faster and more energetic process. more effective (as shown below).

SUMMARY OF THE INVENTION The present invention relates to a process of producing activated carbon from cork material by physical activation, comprising the steps of:

pre-activation of the cork material in an atmosphere comprising steam

400 ° C over a period of water at a temperature of 350 ° C and a time of 15 to 50 minutes; and pyrolysis / activation of the product obtained in the pre-activation step, in an atmosphere consisting of nitrogen and water vapor, at a temperature of 750 to 850 ° C for a time period of 90 minutes.

In one aspect of the present invention, the process comprises a step of cooling the material obtained in the pre-activation step to room temperature.

In another aspect of the present invention the process further comprises a step of cooling the material obtained in the pyrolysis / activation step under inert atmosphere to room temperature.

In yet another aspect of the present invention, the cork material is selected from the group comprising granulated cork, bits, scrap and waste from other industrial processing operations, falk grinding granules and combinations thereof.

In one embodiment of the invention, the temperature of the

In another embodiment of the invention, the pre-activation step takes place within a time period of 19 to 23 minutes.

Still in another form of achievement, in step in pre- activation the relationship between total mass of steam from Water and the mass of cork material be between 1.2 : 1 and

5.5: 1.

In a preferred embodiment, the gaseous atmosphere of the pre-activation step comprises nitrogen and water vapor having a mass ratio of N 2: H 2 O from 2: 1 to 3: 1.

In another preferred embodiment, the temperature of the pyrolysis / activation step is 800 ° C.

In yet another embodiment, the pyrolysis / activation step runs within a time period of 60 to 90 minutes.

In a preferred embodiment, the pyrolysis / activation step runs within a time period of 60 minutes.

In yet another embodiment, the gaseous atmosphere of the pyrolysis / activation step consists of nitrogen and water vapor in a mass ratio of N ₂ : H ₂ O from 2: 1 to 3: 1.

In a preferred embodiment, the gaseous atmosphere of the pyrolysis / activation step consists of nitrogen and water vapor in a mass ratio of 2.7: 1.

In another embodiment, in the pyrolysis / activation step the ratio of total water vapor mass to cork material mass is from 1.5: 1 to 4.8: 1.

In a more preferred embodiment, the process of the present invention comprises the steps of:

(a) pre-activation of the cork material with water vapor under the conditions of:

• water vapor temperature of 380 ° C;

• contact time of 21 minutes;

• ratio between the total mass of water vapor and the mass of cork material of 4.3: 1;

b) cooling the material obtained in step a) to room temperature;

c) raising the temperature of a reactor with a heating rate of 10 ° C / min to a temperature of 800 ° C;

d) pyrolysis / activation of the product obtained in step b) in an atmosphere consisting of nitrogen and water vapor under the following conditions:

• temperature of 800 ° C;

• 60 minute contact time;

• ratio of nitrogen mass flow to 2.7: 1 water vapor mass flow rate;

• ratio of the total mass of water vapor to the mass of cork material fed in step a) of 3.4: 1

DETAILED DESCRIPTION OF THE INVENTION

Cork is a natural material whose average composition is as follows:

• suberine (45%) - is the main component of the cellular structure of cork;

• lignin (27%);

• polysaccharides (12%) - cell wall components that define the texture of cork;

• tannins (6%);

• ceroids (5%) - hydrophobic compounds that ensure the impermeability of cork.

From the above composition it appears that cork is a low carbon and carbon rich material, so that the by-products of its forest production and industrial transformation process meet the necessary conditions to be considered as a starting material for the production of activated carbon. , thus allowing the recovery of a low economic value waste into a high value added product.

The term cork or simply cork material used in the present description refers to granulated cork with different densities and / or particle size, planks, panels, pieces, scrap and waste from other processing operations.

processing industrial, as well as grainy resulting gives crushing falca (this it is virgin cork, second hand or from pruning) and its combinations. A coal activated can be characterized by your apparent specific area and still through the full volume of

pores and the total volume of the micropores.

The apparent specific area of an activated carbon, measured in m ² .g - ¹ , is generally obtained from gas adsorption determinations, namely nitrogen at 77 K, according to the Brunauer-Emmett-Teller theory and designated by specific BET area, or in short by BET Area.

In general, the higher the apparent specific area, the greater the adsorption capacity of an activated carbon. An acceptable minimum value for the BET apparent specific area of an activated charcoal is considered to be in the order of 500 m ² .g ^-1 and the usual values are in the range of 600 - 1200 m ² . g ~ ² .

The specific area limits the amount of material that can be adsorbed and is directly related to the volume of narrower pores (micropores).

According to the IUPAC classification pores can be classified according to their diameter into:

i. Micropores - diameter less than 2 nm.

ii. Mesoporos - diameter between 2 and 50 nm.

iii. Macropores - diameter greater than 50 nm.

Adsorption occurs predominantly in micropores, with mesopores and macropores important as transport channels.

Total pore volume is determined according to Gurvich's rule, which assumes that at relative pressures close to 1 the adsorbate is in the liquid state. In an activated carbon the total pore volume corresponds to the sum of the volume of micro and mesopores.

The pore diameter distribution determines the most suitable application type for each activated carbon.

Unless otherwise indicated, the ranges of values set forth herein are intended to provide a simplified and technically acceptable way to indicate each individual value within its range. By way of example, the expression 1 to 2 or between 1 and 2 means any value within this range, for example 1.0; 1.1; 1,2; 1.3; 1.4;

1.5; 1.6; 1.7; 1.8; 1.9; 2.0. All values mentioned in the present description should be interpreted as approximate values, for example the reference to 2.0 means about 2.0.

Note that regardless of the explicit presentation of a quantitative expression about X, any X value presented during the present description should be interpreted as an approximate value of the actual X value, since such approximation to the actual value would be reasonably expected by the expert. in the art due to experimental and / or measurement conditions that introduce deviations from the actual value.

The present invention relates to a process of producing activated carbon from a cork material by physical activation, comprising the steps of:

pre-activating the cork material in an atmosphere comprising water vapor at a temperature of 350 to 400 ° C for a period of 15 to 30 minutes; and pyrolysis / activation of the product obtained in the pre-activation step in an atmosphere consisting of nitrogen and water vapor at a temperature of 750 to 850 ° C over a period of 30 to 90 minutes.

The term pyrolysis / activation is used herein since, in the process of the present invention, these two transformations occur simultaneously in the second process step.

In one embodiment, the pre-activation step may be performed by subjecting the cork material to an atmosphere consisting of nitrogen and water vapor, in a mass ratio of N ₂ : H ₂ O from 2: 1 to 3: 1, at a temperature between 350 and 400 ° C, preferably between 360 and 380 ° C, more preferably at 380 ° C for a period of time between 15 and 30 minutes, preferably preferred between 19 and 23 minutes.

In a preferred embodiment, the preactivation step may be carried out by subjecting the cork material to a water vapor atmosphere at a temperature between 350 and 400 ° C, preferably between 360 and 380 ° C. C is more preferably at 380 ° C for a period of time between 15 and 50 minutes, preferably between 19 and 23 minutes.

In the pre-activation step of the invention, the ratio between the total water vapor mass (to which the cork material is exposed) and the cork material mass is from 1.2: 1 to 5.5: 1.

The next pyrolysis / activation step may take place immediately following the pre-activation step using the same device or at a later time and on a separate device.

When the pyrolysis / activation step proceeds immediately following the pre-activation step and in the same equipment, the material is subjected to a heating ramp from 350 to 400 ° C to 750 to 850 ° C at a constant rate of 8 to 10 ° C / min, preferably at 10 ° C / min, under nitrogen flow and water vapor.

Then, when the temperature of 750 to 850 ° C is reached, the pyrolysis / activation step is initiated, in which the product resulting from the pre-activation step is subjected to an atmosphere comprising nitrogen and water vapor, in a proportion in mass of

N ₂ : H ₂ O from 2: 1

3: 1, preferably 2.7: 1. This step is preferably performed at 800 ° C for a period of 30 to preferably 60 to 90 minutes, minutes,

more preferred 60 minutes In this step in pyrolysis / activation, the relationship between mass total of steam in water and the mass of material of cork fed on step in

pre-activation is

After the pyrolysis / activation step, the resulting material is cooled to room temperature in an inert atmosphere.

The product obtained in accordance with the present invention has a BET Area significantly greater than that disclosed in the 2007 publication, ie, about 800-820 m ² . g- ¹ versus 660 m ² .g- ¹ , as well as a much higher total pore volume of 0.50 cm ³ . g ~ ² versus 0.35 cm ³ . g ~ ² .

This result is totally unexpected, since the skilled artisan would have no reason to use a first pre-activation step at a temperature significantly below the temperature range commonly used in the physical activation processes and even less expect the process resulted in a product with the physical properties found in the activated carbon of the present invention.

Also the energy cost involved in the process of the present invention is lower than that associated with the process disclosed in said 2007 publication, since the latter involves a first inert atmosphere pyrolysis step followed by an activation step, both performed at temperatures of the order 600 to 800 ° C, whereas in the present invention the pyrolysis step is replaced by a pre-activation of cork in an atmosphere comprising water vapor at significantly lower temperatures (350 to 400 ° C) and for less time, which implies, necessarily an energy gain.

The product resulting from the pre-activation step may further be used as a raw material for the production of chemically activated activated carbon. In this case, the product resulting from the pre-activation step is stirred together with a solution of the activating agent for a certain period of time, after which excess liquid is removed by drying at 110 ° C, followed by pyrolysis of samples impregnated at a given temperature. Finally, it is necessary to grind the activated carbon thus obtained, to wash to remove excess activating agent and its soluble degradation products, and finally to dry the final product thus obtained. The experimental procedure used is described in example 5 below.

For a better understanding of the invention, illustrative and non-limiting examples of the application of the process of the present invention are described below.

EXAMPLES

Example 1

In a thermostated quartz reactor with an internal diameter of 25 mm and a length of 230 mm, 8.5 g of cork granules of 1 to 2 mm were placed.

A nitrogen flow rate of 28.8 L / hour and a water flow rate of 12.5 g / hour were added to the reactor throughout the process, the mass ratio of nitrogen to water being 2.7: 1.

In the pre-activation step, the reactor temperature was raised at a constant rate of 10 ° C / min from room temperature to 380 ° C and the reactor was kept at this temperature for a further 20 minutes.

In this pre-activation step, the ratio between the water mass and the cork mass fed to the reactor was 1.4: 1.

In the second pyrolysis / activation step, the material resulting from the first pre-activation step was heated at a rate of 10 ° C / min to 800 ° C and then kept at 800 ° C for a further 60 minutes.

In this second pyrolysis / activation step, the ratio of water mass to cork mass initially fed to the reactor was 2.5: 1.

The total process time was 158 minutes.

After pyrolysis / activation, the activated carbon was cooled under an inert nitrogen atmosphere to room temperature.

The material obtained was then characterized and the following results were obtained:

BET surface area: 827 m ² . g ^_1

Total pore volume: 0.50 cm ³ . g ~ ²

Micropore volume: 0.33 cm ³ . g ~ ²

Yield: 10.8%.

Comparative Example 1 (Prior Art)

In the same reactor as in the previous example, 8.5 g of cork granules were placed with a particle size between 1 and 2 mm, as in the previous example.

A first pyrolysis step was carried out and a 28.8 L / hour nitrogen flow rate

temperature of reactor been raised to a constant rate in 10 ° C / min up until reach 800 ° C and, after, kept at 800 ° c, for more 60 minutes (such as usually made we

prior art processes).

A 28.8 L / hour nitrogen flow rate and a 12.5 g / hour water flow rate were then introduced into the reactor, with the mass ratio of nitrogen to water being about 2.7: 1, as in the previous example.

The activation step was carried out for 60 minutes at 800 ° C.

The total process time was 198 minutes.

After activation the activated carbon was cooled under an inert nitrogen atmosphere to room temperature.

The material obtained was characterized and the following results were obtained:

BET surface area: 782 m ² . g ^_1

Total porous volume: 0.48 cm ³ . g ~ ²

Micropore volume: 0.32 cm ³ . g ~ ²

Yield: 10.6%

Comparing the present results with those obtained in Example 1, it is found that, to obtain an activated carbon with a BET area and a slightly lower total pore volume, the energy cost is necessarily higher due to its longer lifetime and higher temperatures from your first step.

Example 2

The same procedure as in Example 1 above was used, except that the pyrolysis / activation step was conducted at 800 ° C for 90 minutes.

Consequently, in the pyrolysis / activation step, the ratio of water mass to cork mass initially fed to the reactor was 3.2: 1.

The total process time was 188 minutes.

The material obtained was then characterized and the following results were obtained:

BET surface area: 886 m ² . g ^_1

Total pore volume: 0.57 cm ³ . g ~ ³

Micropore volume: 0.34 cm ³ . g ~ ³

Yield: 5.7%

Example 3

The cork material used was the hawk crushing granulate.

In the first pre-activation step, water vapor at 380 ° C was applied to the cork material for 21 minutes, with the ratio of total water mass to cork material being 4.3. :1.

Upon completion of this first step, the product was cooled to room temperature.

One week later, the product from the pre-activation step was introduced into the reactor described in the previous examples and the pyrolysis / activation step was carried out by subjecting said product to a mixture of nitrogen and water vapor, in the proportions and flow rates of the particles. previous examples, the reactor temperature having been raised from room temperature to 800 ° C with a heating rate of 10 ° C / min and then at 800 ° C for a further 60 minutes.

In this pyrolysis / activation step, the ratio of the total water vapor mass to the mass of cork material fed in the pre-activation step was 3.4: 1.

Following this pyrolysis / activation step, the activated charcoal was cooled under an inert nitrogen atmosphere to room temperature.

The material obtained was then characterized and the following results were obtained:

BET surface area: 801 m ² . g ” ¹

Total pore volume: 0.54 cm ³ . g ” ¹

Micropore volume: 0.30 cm ³ . g ” ¹

Yield: 10.4%

Example 4

Using the same procedure as in example 3 above, several assays were performed by varying the temperature (T _pa ) and duration time (t _pa ) of the second pyrolysis / activation step.

The results obtained are presented in table 1, which also included, for ease of reading and comparison of results, the data related to example 3.

Table 1 - Characterization of activated carbons ^**

Test No. T _pa (° C) -1- * * ^L pa (min) BET area (m ² .g ^_1 ) Porous volume (cm ^3. G ~ ² ) Micropore volume (cm ^3. G ~ ² ) Yield (%) 1 700 60 475 0.27 0.20 17.2 2 750 60 633 0.41 0.24 19.0 3 800 30 515 0.28 0.22 12.4 4 (Ex.3) 800 60 801 0.54 0.30 10, 4 5th 800 90 810 0.56 0.29 6.5 6th 850 60 496 0.33 0.19 2,3 7th 900 60 ___ * ___ * ___ * 0.0

* - only ash obtained ** - does not include heating ramp to final pyrolysis / activation step temperature.

Example 5 Material resulting from the first step described in Example 3 was stirred for a time (t _a ) in contact with an aqueous solution of the activating agent.

After removal of excess liquid by drying at 110 ° C, the resulting impregnated material was subjected to a pyrolysis step with a take-up ramp (T _x ) until reaching a temperature (T _a ) which then remained constant over time (t _a ) ·

The resulting material was milled, washed with water to remove excess activating agent, and dried at a temperature of 110 ° C. Table 2 specifies the experimental conditions used and the results obtained are presented in table 3.

Table 2 - chemical activation - experimental conditions

Test No. Activating Agent Precursor mass portion: activator you (hours) T * - ¹ - X (° C / min) T _a (° C) t _a (hours) 1 K ₂ CO ₃ 1: 1 24 10 700 1 2 K2CO3 1: 2 24 10 700 1 3 K2CO3 1: 1 24 10 800 1 4 KOH 1: 1 2 10 700 1 5th KOH 1: 2 2 10 700 1 6th KOH 1: 1 2 10 800 1

* - T _x : heat up rate until reaching temperature T _a

Table 3 - chemical activation - characterization of the obtained coals

Test No. BET area (m ² .g ^_1 ) Porous volume (cm ^3. G ~ ² ) Micropore volume (cm ^3. G ~ ² ) Yield (%) 1 617 0.29 0.27 35.2 2 604 0.30 0.26 34.6 3 907 0.42 0.40 27.5 4 729 0.35 0.32 22.9 5th 874 0.41 0.38 5.9 6th 948 0.47 0.41 24.5

The resulting activated carbon has been found to have textural properties similar to those obtained by directly subjecting cork to a chemical activation process.

Lisbon, November 13, 2012

Claims (12)

1. Process of producing activated carbon from cork material by physical activation, comprising the steps of: pre-activating the cork material in an atmosphere comprising water vapor at a temperature of 350 to 400 ° C for a period of 15 to 50 minutes; and pyrolysis / activation of the product obtained in the pre-activation step in an atmosphere consisting of nitrogen and water vapor at a temperature of 750 to 850 ° C over a period of 30 to 90 minutes. Process of wake up with the claim 1, characterized by understand still one cooling step of material obtained in step in pre-activation to the temperature environment. 3 Process according to claim 1 or 2, further comprising a step of cooling the material obtained in the pyrolysis / activation step under inert atmosphere to room temperature. 4 Process according to claim 1, characterized in that the cork material is selected from the group comprising granulated cork, bits, scrap and waste from other industrial processing operations, granules resulting from the crushing of the falk and combinations thereof. Process according to Claim 1, characterized in that the temperature of the pre-activation step is 380 ° C. Process according to Claim 1, characterized in that the pre-activation step takes place within a period of 19 to 23 minutes. Process according to Claim 1, characterized in that in the pre-activation step the ratio of the total water vapor mass to the cork material mass is between 1.2: 1 and 5.5: 1. Process according to Claim 1, characterized in that the gaseous atmosphere of the pre-activation step comprises nitrogen and water vapor having a mass ratio of N 2: H 2 O from 2: 1 to 3: 1. Process according to Claim 1, characterized in that the temperature of the pyrolysis / activation step is 800 ° C. Process according to Claim 1, characterized in that the pyrolysis / activation step takes place within 60 to 90 minutes. Process according to the preceding claim, characterized in that the pyrolysis / activation step takes place within 60 minutes. Process according to Claim 1, characterized in that the gaseous atmosphere of the pyrolysis / activation step consists of in nitrogen and steam from 2: 1 to 3: 1. Water in a mass ratio of N ₂ : H ₂ O of 13. Process of wake up with the claim previous, featured per The atmosphere gaseous step of pyrolysis / activation consists of nitrogen and water vapor in a mass ratio of 2.7: 1. Process according to Claim 1, characterized in that in the pyrolysis / activation step the ratio between the total water vapor mass and the cork material mass is between 1.5: 1 and 4.8: 1. Process according to Claim 1, characterized in that it comprises the steps of: (a) pre-activation of the cork material with water vapor under the conditions of: • water vapor temperature of 380 ° C; • contact time of 21 minutes; • ratio between the total mass of water vapor and the mass of cork material of 4.3: 1; b) cooling the material obtained in step a) to room temperature; c) temperature rise with a heating rate of 10 ° C / min to a temperature of 800 ° C; d) pyrolysis / activation of the product obtained in step b) in an atmosphere consisting of nitrogen and water vapor under the following conditions: • temperature of 800 ° C; • 60 minute contact time; • ratio of nitrogen mass flow to 2.7: 1 water vapor mass flow rate; • ratio of the total mass of water vapor to the mass of cork material fed in step a) of 3.4: 1.