Process for preparing a microporous carbon material and its use as absorption product

Abstract

The invention relates a process for preparing a microporous carbon material comprising the following steps: i) providing a cross-linked polymer obtainable by reacting either A1) a maltodextrin deriving from starch comprising amylose in the range from 25 to 50% expressed as dry weight relative to the dry weight of the starch or A2) a cyclodextrin with an organic aromatic dianhydride in a mass ratio of either maltodextrin or cyclodextrin with respect to the organic aromatic dianhydride in the range of 1:0.50 to 1:2, ii) pyrolyzing at a range from 700 to 900 C. with a heating ramp in the range from 5 C./min to 30 C./min in a inert gas flux; and iii) cooling the obtained residue. The microporous carbon material obtainable by the process of the invention consists of micropores having pore size distribution in the range from about 6 to about 16 and is used as absorber for liquids and gases.

Claims

1. A process for preparing a porous carbon material in which the porosity of said material consists only of pores having pore size distribution in the range from about 6 to about 16 , said method comprising the following steps: i) providing a cross-linked polymer selected from: A1) a cross-linked polymer of maltodextrin and an organic aromatic dianhydride, wherein said maltodextrin of the cross-linked polymer is from starch comprising amylose in the range from 25 to 50% expressed as dry weight relative to the dry weight of the starch, and wherein the mass ratio of maltodextrin to organic aromatic dianhydride is in the range of 1.0:0.50 to 1:2; or A2) a cross-linked polymer of cyclodextrin and an organic aromatic dianhydride, wherein the mass ratio of maltodextrin to organic aromatic dianhydride is in the range of 1.0:0.50 to 1:2; ii) pyrolyzing the provided cross-linked polymer at a range from 700 to 900 C. with a heating ramp in the range from 5 C./min to 30 C./min in an inert gas flux; and iii) cooling the residue obtained by said pyrolyzing, thereby preparing the porous carbon material in which the porosity of said material consists only of pores having pore size distribution in the range from about 6 to about 16 .

2. The process according to claim 1, wherein the organic aromatic dianhydride of step i) is selected from the group consisting of pyromellitic dianhydride, NTCDA (1,4,5,8-naphthalene-tetracarboxylic dianhydride), 3,3,4,4-biphenyltetracarboxylic dianhydride, benzophenone-3,3,4,4-tetracarboxylic dianhydride, 4,4-(hexafluoroisopropylidene)diphthalic anhydride.

3. The process according to claim 2, wherein the organic aromatic dianhydride is pyromellitic dianhydride.

4. The process according to claim 1, wherein the cross-linked polymer comprises a ratio of either maltodextrin or cyclodextrin with respect to the organic aromatic dianhydride in the range of 1:0.60 to 1:1.

5. The process according to claim 1, wherein the cross-linked polymer is maltodextrin with the organic aromatic dianhydride in a mass ratio of 1:0.77.

6. The process according to claim 5 wherein the maltodextrin A1) is from leguminous starch.

7. The process according to claim 6, wherein the leguminous starch is from a plant chosen from the group formed by the pea, bean, broad bean, horse bean and their mixtures.

8. The process according to claim 6, wherein the leguminous starch has an amylose content from 30% to 40%, dry weight relative to the dry weight of starch.

9. The process according to claim 6, wherein the leguminous starch has an amylose content from 35% to 40% dry weight relative to the dry weight of starch.

10. The process according to claim 6, wherein the leguminous starch has an amylose content from 35% to 38% dry weight relative to the dry weight of starch.

11. The process according to claim 1, wherein the maltodextrin has a dextrose equivalent (DE) of 17.

12. The process according to claim 1, wherein the cyclodextrin is selected from the group consisting of -cyclodextrin, -cyclodextrin, -cyclodextrin and their derivatives.

13. The process according to claim 12, wherein the derivative of the cyclodextrin is methyl -cyclodextrin or hydroxypropyl--cyclodextrin.

14. The process according to claim 1, wherein the cross-linked polymer is cyclodextrin with the organic aromatic dianhydride in a mass ratio of 1:0.67, wherein the cyclodextrin is -cyclodextrin.

15. The process according to claim 1, wherein the cross-linked polymer is cyclodextrin with the organic aromatic dianhydride in a mass ratio of 1:0.77, wherein the cyclodextrin is -cyclodextrin.

16. The process according to claim 1, wherein the inert gas flux is a nitrogen flux, preferably of 100 ml/min.

17. The process according to claim 1, wherein the ramp temperature of the pyrolysis step ii) is 10 C./min.

18. The process according to claim 1, wherein the pyrolysis temperature is 800 C.

19. The process according to claim 1, wherein the cross-linked polymer is cyclodextrin with the organic aromatic dianhydride in a mass ratio of 1:0.90, wherein the cyclodextrin is -cyclodextrin.

Description

DESCRIPTION OF THE FIGURES

(1) FIG. 1 shows the modification in weight percentage of carbon material of example 1 by varying the ramp temperature.

(2) FIG. 2 shows the modification in weight percentage of carbon material of example 2 by varying the ramp temperature.

(3) FIG. 3 shows the modification in weight percentage of carbon material of example 1 by varying the pyrolysis temperature.

(4) FIG. 4 shows the modification in weight percentage of carbon material of example 2 by varying the pyrolysis temperature.

(5) FIGS. 5a and 5b show pictures of optical microscope and SEM microscope (magnification 200) of the carbon materials of example 1.

(6) FIG. 5c shows pictures of SEM microscope of the carbon material of example 1 at magnification of 20.

(7) FIG. 5d shows picture of optical microscope of the carbon material of example 2.

(8) FIGS. 5e and 5f show pictures of SEM microscope of the carbon material of example 2 at magnification of 350 and 500, respectively.

(9) FIG. 6 shows plot of incremental pore volume vs pore width of the porous carbon material of example 1.

(10) FIG. 7 shows plot of incremental pore volume vs pore width of the porous carbon material of example 2.

(11) FIG. 8 shows UV spectra of carbon materials of example 1 and example 2 after absorption of methyl orange solution (10 ppm).

(12) FIG. 9 shows isotherms of the absorption of water of the carbon material of example 2.

(13) FIG. 10 shows isotherms of the absorption of CO.sub.2 of the carbon material of example 1.

(14) FIG. 11 shows isotherms of the absorption of CO.sub.2 of the carbon material of example 2.

(15) FIG. 12 show TGA graphs of the carbon materials of Example 1 and example 2.

(16) FIG. 13 show TGA graphs of the carbon materials of Example 3 and Example 4.

(17) FIG. 14 shows plot of incremental pore volume vs pore width of the porous carbon material of example 3.

(18) FIG. 15 shows plot of incremental pore volume vs pore width of the porous carbon material of example 4.

DETAILED DESCRIPTION OF THE INVENTION

(19) The invention relates to a process for preparing a microporous carbon material comprising the following steps: i) providing a cross-linked polymer obtainable by reacting either A1) a maltodextrin deriving from starch comprising amylose in the range from 25 to 50% expressed as dry weight relative to the dry weight of the starch or A2) a cyclodextrin with an organic aromatic dianhydride in a mass ratio of either maltodextrin or cyclodextrin with respect to the organic aromatic dianhydride in the range of 1:0.50 to 1:2; ii) pyrolyzing at a range from 700 to 900 C. with a heating ramp in the range from 5 C./min to 30 C./min in an inert gas flux; and iii) cooling the obtained residue.

(20) The mass ratio of either maltodextrin or cyclodextrin with respect to the organic aromatic dianhydride is in the range of 1:0.50 to 1:2, preferably 1:0.60 to 1:1.

(21) The organic aromatic dianhydride of step i) is preferably selected from the group consisting of pyromellitic dianhydride, NTCDA (1,4,5,8-naphthalene-tetracarboxylic dianhydride), 3,4,4-biphenyltetracarboxylic dianhydride, benzophenone-3,3,4,4-tetracarboxylic dianhydride, 4,4-(hexafluoroisopropylidene)diphthalic anhydride. More preferably the organic aromatic dianhydride is pyromellitic dianhydride.

(22) According to a first embodiment of the invention the process comprises the step of providing a cross-linked polymer obtainable reacting A1) a maltodextrin deriving from starch comprising amylose in the range from 25 to 50% expressed as dry weight relative to the dry weight of the starch with the organic aromatic dianhydride in a mass ratio of the maltodextrin with respect to the organic aromatic dianhydride in the range of 1:0.50 to 1:2.

(23) The maltodextrin A1) was firstly described in US2010/0196542 wherein the maltodextrin is obtained from a leguminous starch having an amylose content comprised between 25% and 50%, expressed as dry weight relative to the dry weight of starch. As explained in such a document, amylose is organized in helices with a hydrophilic external surface due to the presence of hydroxyl groups and with a hydrophobic internal surface due to the presence of hydrogen atoms. Preferably the maltodextrin of the invention derives from leguminous starch. By leguminous is meant within the meaning of the present invention any plant belonging to the families of the Caesalpiniaceae, Mimosaceae or Papilionaceae and notably any plant belonging to the family of the Papilionaceae such as, for example, pea, bean, broad bean, horse bean, lentil, lucerne, clover or lupin. This definition includes in particular all the plants described in any one of the tables contained in the article by R. HOOVER et al., 1991 (HOOVER R. (1991) Composition, structure, functionality and chemical modification of leguminous starches: a review Can. J. Physiol. Pharmacol., 69, pp.: 79-92). Preferably, the leguminous plant is chosen from the group formed by the pea, bean, broad bean, horse bean and their mixtures. According to a preferred and advantageous embodiment, the leguminous plant is a variety of pea or horse bean, producing seeds containing at least 25%, preferably at least 40%, by weight of starch (dry/dry). More advantageously, said leguminous plant is the pea. The term pea being here considered in its broadest sense and including in particular: all the wild smooth pea varieties and all the mutant smooth pea and wrinkled pea varieties, irrespective of the uses for which said varieties are generally intended (human consumption, animal nutrition and/or other uses).

(24) The leguminous starch of the invention preferably has an amylose content comprised between 30% and 40%, in particular comprised between 35% and 40%, and more preferably between 35% and 38%, these percentages being expressed as dry weight relative to the dry weight of starch. The maltodextrins are conventionally obtained by acid and/or enzymatic hydrolysis of starch. Referring to the regulatory status, the maltodextrins have a dextrose equivalent (DE) of 1 to 20. Preferably in the present invention the maltodextrin has a dextrose equivalent (DE) of 17 and an average molecular weight by weight of about 12000 D.

(25) The cross-linked polymer is hence obtainable from reacting the maltodextrin A1 with the organic aromatic dianhydride in a mass ratio in the range of 1:0.50 to 1:2, preferably 1:0.60 to 1:1. More preferably the mass ratio is about 1:0.77. The cross-linked polymer of A1) of step i) contains a number of helices with bridges deriving from the organic aromatic dianhydride. More preferably the organic aromatic dianhydride is pyromellitic dianhydride.

(26) The cyclodextrin of step i)A2) can be -cyclodextrin, -cyclodextrin, -cyclodextrin or their derivatives. The derivative of the cyclodextrin can be methyl -cyclodextrin or hydroxypropyl--cyclodextrin.

(27) According to a second embodiment of the invention the process comprises the step of providing a cross-linked polymer obtainable reacting A2) -cyclodextrin with the organic aromatic dianhydride in a mass ratio in the range of 1:0.50 to 1:2, preferably 1:0.60 to 1:1. More preferably the mass ratio is about 1:0.77. The molar ratio of the -cyclodextrin with respect to the organic aromatic dianhydride is about 1:4.

(28) The cross-linked polymer of the second embodiment obtainable by reacting A2) as -cyclodextrin with the organic aromatic dianhydride is a polymer of units of -cyclodextrin with cross-linking bridges of the organic aromatic dianhydride covalently linked to the units of -cyclodextrin. More preferably the organic aromatic dianhydride is pyromellitic dianhydride.

(29) According to a third embodiment of the invention the microporous carbon material is obtainable by a cross-linked polymer obtainable by reacting -cyclodextrin and the organic aromatic dianhydride in a mass ratio of the -cyclodextrin with respect to the organic aromatic dianhydride in a ratio in the range of 1:0.50 to 1:2, preferably 1:0.60 to 1:1. More preferably the mass ratio is about 1:0.90. The molar ratio of the -cyclodextrin with respect to the organic aromatic dianhydride is about 1:4.

(30) The cross-linked polymer of the third embodiment obtainable by reacting A2) as -cyclodextrin with the organic aromatic dianhydride is a polymer of units of -cyclodextrin with cross-linking bridges of the organic aromatic dianhydride covalently linked to the units of -cyclodextrin. More preferably the organic aromatic dianhydride is pyromellitic dianhydride.

(31) According to the fourth advantageous embodiment of the invention the microporous carbon material is obtainable by a cross-linked polymer obtainable by reacting -cyclodextrin and the organic aromatic dianhydride in a mass ratio of the -cyclodextrin with respect to the organic aromatic dianhydride in a ratio in the range of 1:0.50 to 1:2, preferably 1:0.60 to 1:1. More preferably the mass ratio is about 1:0.67. The molar ratio of the -cyclodextrin with respect to the organic aromatic dianhydride is about 1:4. The cross-linked polymer of the fourth embodiment obtainable by reacting A2) as -cyclodextrin with the organic aromatic dianhydride is a polymer of units of -cyclodextrin with cross-linking bridges of the organic aromatic dianhydride convalently covalently linked to the units of -cyclodextrin. More preferably the organic aromatic dianhydride is pyromellitic dianhydride.

(32) In all the embodiments of the invention in the step i) of the preparation of the cross-linked polymer a tertiary amine is preferably used as catalyst, more preferably triethylamine.

(33) Without being bound to any theory the inventors deem that the optimal constant physical features of the final microporous carbon material seemed to be guaranteed by the use of the organic aromatic dianhydride as cross-linking agent and by the specific mass ratio of either maltodextrin or cyclodextrin with respect to the organic aromatic dianhydride in the range of 1.50 to 1:2, preferably 1:60 to 1:1, to achieve the cross-linked polymer between either A1) or A2) and the organic aromatic dianhydride.

(34) In step ii) the cross-linked polymer of step i) is subjected to pyrolysis in the range of 700-900 C. with a ramp in the range from 5 C./min to 30 C./min in an inert gas flux. Preferably, the inert gas flux is of about 100 ml/min, more preferably the inert gas flux is a nitrogen flux. Preferably the ramp is 10 C./min, more preferably in a nitrogen flux. Preferably the temperature of the pyrolysis is 800 C.

(35) In step iii) the carbon mass obtained by step ii) is cooled preferably through inert gas flux in order to avoid any oxidation reaction, more preferably until the samples are below 200 C.

(36) The microporous carbon material of the invention consists of micropores having pore size distribution in the range from about 6 to about 16 .

(37) In the present invention the pore size distributions were characterized by nitrogen adsorption-desorption isotherms obtained with an automatic adsorption instrument (ASAP 2020). This instrument allows the characterization of surface area and pore structure. The basics of the analytical technique is as follows. The sample is degased at 300 C. and then a sample contained in an evacuated sample tube is cooled to nitrogen cryogenic temperature, then it is exposed to nitrogen gas at a series of precisely controlled pressures (from 0 to 1 of nitrogen relative pression). With each incremental pressure increase, the number of gas molecules adsorbed on the surface increases. The pressure at which adsorption equilibrium occurs is measured and the universal gas law is applied to determine the quantity of gas adsorbed. As adsorption proceeds, the thickness of the adsorbed film increases. Any micropores in the surface are quickly filled, then the free surface becomes completely covered, and finally larger pores are filled. The process may continue to the point of bulk condensation of the analysis gas. Then, the desorption process may begin in which pressure systematically is reduced resulting in liberation of the adsorbed molecules.

(38) As with the adsorption process, the changing quantity of gas on the solid surface is quantified. These two sets of data describe the adsorption and desorption isotherms. Analysis of the isotherms yields information about the surface characteristics of the material.

(39) The models used for the surface area was the Langmuir model. The volume and the pore distribution was determined with DFT model.

(40) The microporous carbon material of the first embodiment of the invention, i.e. obtainable by the cross-linked polymer of A1) has pore size distribution in the range from about 7 to about 12

(41) The microporous carbon material of the second embodiment of the invention, i.e. obtainable by the cross-linked polymer of A2), wherein the cyclodextrin is -cyclodextrin has pore size distribution in the range from about 6 to about 16 .

(42) The microporous carbon material of the third embodiment of the invention, i.e. obtainable by the cross-linked polymer of A2) wherein the cyclodextrin is -cyclodextrin, has pore size distribution in the range from about 7 to about 15 .

(43) The microporous carbon material of the fourth embodiment of the invention, i.e. obtainable by the cross-linked polymer of A2), wherein the cyclodextrin is -cyclodextrin has pore size distribution in the range from about 7 to about 15 .

(44) The microporous carbon material of the invention shows a high BET SS area.

(45) The microporous carbon material of the invention shows a high absorption of compound solution and gases. Therefore the microporous carbon material finds applications as drug delivery system showing optimal absorption of drug solution, and as absorber material of CO.sub.2. Advantageously and as it will be evident from the experimental part of the present description the microporous carbon material is capable to absorb CO.sub.2 in amounts higher than the active known carbon material.

(46) The invention will be now described with reference to examples of preparation of the polymer of the invention and examples of absorption.

EXPERIMENTAL PART

Example 1: Preparation of Microporous Carbon Material According to the First Embodiment of the Invention

(47) Step i) Preparation of the cross-linked polymer by reacting A1) a maltodextrin deriving from starch comprising amylose in the range from 25 to 50% expressed as dry weight relative to the dry weight of the starch and pyromellitic dianhydride as cross-linking agent.

(48) 4.89 g of maltodextrin sold as Kleptose Linecaps 17 from Roquette Italia SpA, having DE of 17 (dried in stove at 100-120 C. for at least one night) were solubilized under continued stirring in 20 ml of dimethyl sulfoxide in a 100 ml flask. 5 ml of triethylamine were then added and, after a few minutes, 3.76 g of pyromellitic dianhydride were added. The mass a ratio of the maltodextrin with respect to pyromellitic dianhydride was 1:0.77. The molar ratio between the initial maltodextrin and pyromellitic dianhydride was 1:0.57 expressed as molar ratio of one mole of glucose of the maltodextrin with respect to 0.57 moles of pyromellitic dianhydride (Molar mass of the glucose unit of 162.145 g/ml). After a short time, the reticulation process blocked the stir bar. After 24 hours the reaction was considered complete. In the following days, the polymer was ground in a mortar and washed with deionized water in a Buchner funnel with water jet pump. After the air drying, the polymer was purified in a Soxhlet extractor with acetone for a total time of about 14 hours.

(49) Step ii) and iii) Pyrolysis of the Cross-Linked Polymer and Consequent Cooling

(50) The cross-linked polymer so obtained was subjected to pyrolysis in a single step. The cross-linked polymer was heated to 800 C. with a temperature ramp of 10 C./min in nitrogen flux (100 ml/min). Specifically, 15 mg of the cross-linked polymer obtained by step I) were placed in a alumina plate for TGA and then placed in a furnace under nitrogen flux at 30 C. and subjected to a planned heating of 10 C. per min until reaching 800 C. The mass so obtained was then cooled and the carbon material was recovered. 5.25 mg of carbon material were obtained (yield 35%). The pyrolysis process was followed with TGA analysis.

Example 2: Preparation of Microporous Carbon Material According to the Second Embodiment of the Invention

(51) Step i) 4 ml of dimethyl sulfoxide (DMSO) and 0.9772 g of -cyclodextrin are added in a glass vial under stirring until they were solubilized. 1 ml of triethylamine as catalyst was then added.

(52) After a few minutes 0.7512 g of pyromellitic dianhydride were added. The mass ratio of the -cyclodextrin with respect to pyromellitic dianhydride was 1:0.77. The molar ratio between the initial -cyclodextrin and pyromellitic dianhydride was 1:4. After 24 hours the reaction was considered complete and the mass was washed with deionized water in a Buchner funnel and then with acetone, thus allowing to dry for a day.

(53) The next step was the purification of Soxhlet funnel with acetone. The extraction lasted 20 hours. The cross-linked polymer so obtained was allowed to dry.

(54) Step ii) and iii) Pyrolysis of the Cross-Linked Polymer and Consequent Cooling

(55) The cross-linked polymer so obtained was subjected to pyrolysis in a single step. The cross-linked polymer was heated to 800 C. with a temperature ramp of 10 C./min in nitrogen flux (60 ml/min). Specifically, 15 mg of the cross-linked polymer obtained by step i) were placed in a alumina plate for TGA and then placed in a furnace under nitrogen flux at 30 C. and subjected to a planned heating of 10 C. per min until reaching 800 C. The mass so obtained was then cooled and the carbon material was recovered. 4.35 mg of carbon material were obtained (yield 29%). The pyrolysis process was followed with TGA analysis.

Example 3: Preparation of Microporous Carbon Material According to the Third Embodiment of the Invention

(56) Step i) 20 ml of dimethyl sulfoxide (DMSO) and 4.8860 g of -cyclodextrin are added in a glass vial under stirring until they were solubilized. 5 ml of triethylamine as catalyst was then added.

(57) After a few minutes 4.3820 g of pyromellitic dianhydride were added. The mass ratio of the -cyclodextrin with respect to pyromellitic dianhydride was 1:0.90. The molar ratio between the initial maltodextrin and pyromellitic dianhydride was 1:4. After 24 hours the reaction was considered complete and the mass was washed with deionized water in a Buchner funnel and then with acetone, thus allowing to dry for a day.

(58) The next step was the purification of Soxhlet funnel with acetone. The extraction lasted 14 hours. The cross-linked polymer so obtained was allowed to dry.

(59) Step ii) and iii) Pyrolysis of the Cross-Linked Polymer and Consequent Cooling

(60) The cross-linked polymer so obtained was subjected to pyrolysis in a single step. The cross-linked polymer was heated to 800 C. with a temperature ramp of 10 C./min in nitrogen flux (100 ml/min). Specifically, 15 mg of the cross-linked polymer obtained by step i) were placed in a alumina plate for TGA and then placed in a furnace under nitrogen flux at 30 C. and subjected to a planned heating of 10 C. per min until reaching 800 C. The mass so obtained was then cooled and the carbon material was recovered. 4.2 mg of carbon material were obtained (yield 28%). The pyrolysis process was followed with TGA analysis.

Example 4: Preparation of Microporous Carbon Material According to the Fourth Embodiment of the Invention. (gamma)

(61) Step i) 20 ml of dimethyl sulfoxide (DMSO) and 4.8860 g of -cyclodextrin are added in a glass vial under stirring until they were solubilized. 5 ml of triethylamine as catalyst was then added.

(62) After a few minutes 3.2865 g of pyromellitic dianhydride were added. The mass ratio of the -cyclodextrin with respect to pyromellitic dianhydride was 1:0.67. The molar ratio between the initial maltodextrin and pyromellitic dianhydride was 1:4. After 24 hours the reaction was considered complete and the mass was washed with deionized water in a Buchner funnel and then with acetone, thus allowing to dry for a day.

(63) The next step was the purification of Soxhlet funnel with acetone. The extraction lasted 14 hours. The cross-linked polymer so obtained was allowed to dry.

(64) Step ii) and iii) Pyrolysis of the Cross-Linked Polymer and Consequent Cooling

(65) The cross-linked polymer so obtained was subjected to pyrolysis in a single step. The cross-linked polymer was heated to 800 C. with a temperature ramp of 10 C./min in nitrogen flux (100 ml/min). Specifically, 15 mg of the cross-linked polymer obtained by step i) were placed in a alumina plate for TGA and then placed in a furnace under nitrogen flux at 30 C. and subjected to a planned heating of 10 C. per min until reaching 800 C. The mass so obtained was then cooled and the carbon material was recovered. 4.43 mg of carbon material were obtained (yield 29.5%). The pyrolysis process was followed with TGA analysis.

Example 5: Effect of Ramp Temperature on the Final Carbon Materials

(66) The same ingredients and the same procedures as stated in example 1 for the first embodiment of the invention and in the example 2 for the second embodiment of the invention were repeated using a different ramp of temperatures, i.e. 5 C./min, 20 C./min and 30 C./min during step ii).

(67) The results are shown in FIG. 1 and in FIG. 2, respectively.

(68) As it is evident from FIGS. 1 and 2 both the crosslinked polymers do not show modifications in the amount of carbon residue by varying the ramp of temperature.

Example 6: Effect of Pyrolysis on the Final Carbon Materials

(69) The same ingredients and the same procedures as stated in example 1 for the first embodiment of the invention and in the example 2 for the second embodiment of the invention were repeated using 700, 800 C. and 900 C. as pyrolysis temperature of step ii). The results are shown in FIG. 3 and in FIG. 4, respectively.

(70) As it is evident form the FIGS. 3 and 4, both the crosslinked polymers do not show losses of weight when 900 C. was reached and the amount of carbon material at 700 C. and 800 C. was very similar.

(71) From FIGS. 3-4 hence it was evident that the pyrolysis could occur at a temperature in the range 700-900 C.

Example 7: Analysis of the Carbon Materials Obtained by Example 1 and Example 2

(72) The elemental analysis of the cross-linked polymer with A1) of example 1 was: 2.755% of nitrogen, 50.204% of carbon, 6.328% of hydrogen and 0.00% of Sulfur, being the oxygen percentage the remaining to 100%.

(73) The elemental analysis of cross-linked polymer with A2) of example 2 (with -cyclodextrin) was: 3.089% of nitrogen, 48.941% of Carbon, 6.178% of hydrogen and 0.00% of Sulfur, being the oxygen percentage the remaining to 100%.

(74) The elemental analysis of cross-linked polymer with A1) of example 1 after pyrolysis at 800 C. shows: 1.41% of nitrogen, 60.24% of carbon, 0.94% of hydrogen and 0.00% of Sulfur, being the oxygen percentage the remaining to 100%.

(75) The elemental analysis of cross-linked polymer with A2) of example 2 (with -cyclodextrin) after pyrolysis at 800 C. was 1.546% of nitrogen, 87.270% of carbon, 0.732% of hydrogen and 0.00% of Sulfur, being the oxygen percentage the remaining to 100%.

(76) The carbon materials obtained in examples 1 and 2 were analyzed with optical microscope and through scanning electron microscope (SEM). The pictures are shown in FIGS. 5a-5f. The carbon material obtained had spherical shapes.

(77) The carbon materials were further analyzed in order to determine the size of the pores and the surface area.

(78) Specifically, the carbon material prepared according to example 1 and example 2 showed mono-dimensional micropores.

(79) As stated above the pore size distributions were characterized by nitrogen adsorption-desorption isotherms obtained with an automatic adsorption instrument (ASAP 2020). The details for the instrument and the technique are above reported. As above indicated the models used for the surface area is the Langmuir model. The volume and the pore distribution is determined with DFT model

(80) The results for the microporous carbon material according to example 1 are represented in FIG. 6. As it is evident the pore size distribution of the micropores of the carbon material according to the first embodiment of the invention fall in the range of 7-8 {acute over ()} and in the range of 10-12 {acute over ()}.

(81) The results for the microporous carbon material according to example 1 are represented in FIG. 7. As it is evident the pore size distribution of the micropores of the carbon material according to the first embodiment of the invention fall in the range of 6-16 {acute over ()}.

(82) The porous carbon materials obtained according to the invention were then classified as microporous material according to the IUPAC definition.

(83) The carbon materials according to example 1 and example 2 were also tested to calculate the BET SS area with the same instrument used for the measurement of the pore size distribution as above explained and the results are reported in the table 1 below.

Example 8: Analysis of the Carbon Materials Obtained by Example 3 and Example 4

(84) The carbon materials obtained in examples 3 and 4 were analyzed with optical microscope and through scanning electron microscope (SEM). The carbon material obtained had spherical shapes.

(85) The carbon materials were further analyzed in order to determine the size of the pores and the surface area.

(86) Specifically, the carbon material prepared according to example 3 and example 4 showed mono-dimensional micropores

(87) As stated above the pore size distributions were characterized by nitrogen adsorption-desorption isotherms obtained with an automatic adsorption instrument (ASAP 2020). The details for the instrument and the technique are above reported.

(88) As above indicated the models used for the surface area is the Langmuir model. The volume and the pore distribution is determined with DFT model.

(89) The results for the microporous carbon material according to example 3 are represented in FIG. 14. As it is evident the pore size distribution of the micropores of the carbon material according to the third embodiment of the invention fall in the range of 7-15 {acute over ()}.

(90) The results for the microporous carbon material according to example 4 are represented in FIG. 15. As it is evident the pore size distribution of the micropores of the carbon material according to the first embodiment of the invention fall in the range of 7-15 {acute over ()}.

(91) The porous carbon materials obtained according to the invention were then classified as microporous material according to the IUPAC definition.

(92) The carbon materials according to example 3 and example 4 were also tested to calculate the BET SS area with the same instrument used for the measurement of the pore size distribution as above explained and the results are reported in the table 1 below.

(93) TABLE-US-00001 TABLE 1 Surface Area Pore size Sample (m.sup.2/g) distribution ({acute over ()}) Carbon Material of 234 6-16 example 1 (I batch of synthesis) Carbon Material of 560 8-15 example 1 (II batch of synthesis) Carbon Material of 188 7-8 10-12 example 2 (I batch of synthesis) Carbon Material of 124 7-8 10-15 example 2 (II batch of synthesis) Carbon Material of 424 7-8 10-15 example 3 Carbon Material of 350 7-8 10-15 example 4

Example 9: Absorption Feature

(94) The absorption feature of the carbon materials obtained according to example 2 was verified with 10 ppm methyl orange solution.

(95) The absorption was evaluated with UV Spectra at different times.

(96) The absorption of methyl orange was evaluated. The absorption was evaluated by adding 50 mg of carbon materials of example 2 to a 5 ml of a solution of methyl orange (10 ppm) through the UV-Vis analysis (PerkinElmer lambda 15, =200-650 nm) of the concentration of methyl orange (peak at 464 nm) in time. The results are graphically shown in FIG. 8. As it is evident in FIG. 8, for the materials of the invention the absorption of methyl orange after 7 h was almost complete. Normalizing to 1 g of carbon material for simplicity added to 1 mg of methyl orange in 100 ml of water was able to absorb 0.79 mg of methyl orange after 1 h, 0.93 mg after 3 hours. All of methyl orange was absorbed after 7 hours.

(97) The test was repeated with a water solution of doxorubicin to evaluate the absorption. 4 mg of carbon material obtained according to the example 2 were suspended in 2 mg/ml water solution of doxorubicin. The loading capacity was of 75.29%

Example 10: Absorption Feature of Gases

(98) The evaluation of gases absorption was carried out through a microcalorimeter and the final measurements were carried out at a temperature of 30 C.

(99) During the analysis the initial pressure (pi) and the external temperature (Ti) were measured. When the equilibrium was reached the equilibrium pressure (pe) and the equilibrium temperature (Te) were measured.

(100) For each sample the absorbed amount (Na) was calculated through the gas equation (PV=nRT).

(101) The obtained results were plotted: Na vs pe. Absorption isotherms of the absorbed amount per gram vs equilibrium pressure were obtained.

(102) From this plot it was possible to evaluate the kind of absorption, thus evaluating whether it is either reversible or irreversible.

(103) In order to understand if either a part or the total absorption is irreversible, after the first step of absorption (first absorption) a degassing step was carried out.

(104) Subsequently, a second absorption step (second absorption) was carried out.

(105) When the two obtained absorption isotherms are overlapped, then the process is totally reversible.

(106) When the two obtained absorption isotherms are different, then the process is partially irreversible.

Example 10a: Absorption of Water with the Carbon Material of First Embodiment of the Invention

(107) The isotherms obtained for the carbon material of example 2 is represented in FIG. 9.

(108) As it is evident from FIG. 9 the first isotherm and the second isotherm for the carbon material of example 2 were overlapped, hence the absorption of the water was reversible.

Example 10b: Absorption of CO2 with the Carbon Material of First Embodiment of the Invention

(109) The isotherms obtained for the carbon material of example 1 are represented in FIG. 10.

(110) As it is evident from FIG. 10 the first isotherm, the second isotherm and the third isotherm for the carbon material of example 1 were not overlapped, hence the absorption of the CO.sub.2 was irreversible.

(111) The maximum absorption for the first absorption of CO.sub.2 was 1287 mol/g.sub.sample which correspond to 56.6 mg/g.sub.sample at a pressure of 461 mbar. According to the literature, the best active carbon is capable to absorb about 60 mg/g of CO.sub.2 at atmospheric pressure or higher.

(112) As to the maximum absorbed amount for the other two immissions of CO.sub.2, the following were retrieved: second absorption: 39.05 mg/g.sub.sample at pressure of 355 mbar. third absorption: 39.39 mg/g.sub.sample at pressure of 401 mbar.

(113) The test was repeated by using also nitrogen: the carbon material of the invention did not absorb the gas and it was not possible to draw the isotherm. Therefore the carbon materials of the invention absorbed selectively CO.sub.2 and did not have interaction with N.sub.2.

Example 10c: Absorption of CO2 of the Carbon Material of the Second Embodiment of the Invention

(114) The isotherms obtained for the carbon material of example 2 are represented in FIG. 11.

(115) As it is evident from FIG. 11 the first isotherm, the second isotherm and the third isotherm for the carbon material of example 2 were overlapped, hence the absorption of the CO2 was reversible.

(116) The maximum absorption for the first absorption of CO.sub.2 was 45.23 mg/g.sub.sample at a pressure of 370 mbar.

(117) As to the maximum absorbed amount for the other two immissions of CO.sub.2, the following were retrieved: second absorption: 45.45 mg/g.sub.sample at pressure of 345 mbar. third absorption: 50.07 mg/g.sub.sample at pressure of 658 mbar.

Example 11: Stability of the Microporous Carbon Material of the Invention

(118) The carbon materials obtained by the Example 1 and Example 2 were heated under nitrogen for TGA analysis.

(119) The TGA for the both materials is reported in FIG. 12.

(120) As it is seen from FIG. 12, the carbon material of Example 2 started the degradation at 650 C., while that of Example 1 at 400 C. The losses of weight for both materials were low: 2% for the carbon material of Example 2 and 13% for the carbon material of example 1.

Example 12: Stability of the Microporous Carbon Material of the Invention

(121) The carbon materials obtained by the Example 3 and Example 4 were heated under nitrogen for TGA analysis.

(122) The TGA for the both materials is reported in FIG. 13.

(123) As it is seen from FIG. 13, the carbon material of Example 3 started the degradation at 250 C., while that of Example 4 at 245 C. The losses of weight for both materials were low: 28% for the carbon material of Example 3 and 29% for the carbon material of example 4.