GATTI GIORGIO (IT)
TEI LORENZO (IT)
COSSI MAURIZIO (IT)
MARCHESE LEONARDO (IT)
VALTOLINA DANIELE (IT)
SALERI PARIDE (IT)
OMB SALERI S P A (IT)
EP2450390A1 | 2012-05-09 | |||
US20120270731A1 | 2012-10-25 |
ROBERT DAWSON ET AL: "Microporous organic polymers for carbon dioxide capture-Supplementary Information", ENERGY & ENVIRONMENTAL SCIENCE, 15 August 2011 (2011-08-15), pages 1 - 23, XP055090876, Retrieved from the Internet
BUYI LI ET AL: "A New Strategy to Microporous Polymers: Knitting Rigid Aromatic Building Blocks by External Cross-Linker", MACROMOLECULES, vol. 44, no. 8, 26 April 2011 (2011-04-26), pages 2410 - 2414, XP055090879, ISSN: 0024-9297, DOI: 10.1021/ma200630s
DAWSON R. ET AL., ENERGY ENVIRON. SCI., vol. 4, 2011, pages 4239 - 4245
TENG BEN ET AL., ANGEW. CHEM. INT. ED., vol. 48, 2009, pages 9457 - 9460
TENG BEN ET AL., ANGEW. CHEM. INT. ED., vol. 48, 2009, pages 9457 - 9460
TENG BEN ET AL., ENERGY ENVIRON. SCI., vol. 4, 2011, pages 3991 - 3999
CLAIMS 1. A method of preparing a gas-adsorbing porous organic polymer, comprising reacting a monomer of formula (I): B E A C D formula (I) wherein A is selected from a C atom, a Si atom, a Ge atom,a Sn atom, an adamantane group, an ethane group and an ethene group, and wherein each of B, C, D and E is a 6-membered ring structure selected from the monovalent radicals of the compounds benzene, pyridine, pyran, cyclopentadiene, pyrrole, furan, tiophene and naphtalene, anthracene, phenanthrene, pyrene, optionally having one or more substituents selected from nitro, amino, hydroxyl, sulfonyl, halogen, phenyl, alkyl, haloalkyl, hydroxyalkyl, aminoalkyl, aryl, alkenyl and alkynyl groups, with a Friedel-Crafts catalyst in an aprotic organic solvent and with formaldehyde dimethyl acetal (FDA), characterized in that the monomer of formula(I):FDA molar ratio is comprised within the range of 1 :9 to 1 :30, preferably is of about 1 : 16. 2. The method according to claim 1, wherein the Friedel-Crafts catalyst is selected from the group consisting of BF3, BeCl2, TiCl4, SbCl5, SnCl4, FeCl3, A1C13, Sc(OTf)3, Mo(CO)6, SeCl4, TeCl4, sulfuric acid, hydrofluoric acid and super acids. 3. The method according to claim 1 or 2, wherein the aprotic organic solvent is selected from the group consisting of dichloroethane (DCE), toluene, benzene, nitromethane (CH3N02), carbon disulfide and chlorobenzene. 4. The method according to any of claims 1 to 3, wherein each of B, C, D and E in formula (I) is a monovalent radical of benzene optionally bearing one or more substituents from nitro, amino, hydroxyl, sulfonyl, halogen, phenyl, alkyl, haloalkyl, hydroxyalkyl, aminoalkyl, aryl, alkenyl and alkynyl groups. 5. The method according to any of claims 1 to 4, wherein the monomer of formula (I) is first reacted with the Friedel-Crafts catalyst in the aprotic organic solvent and then FDA is added. 6. The method according to claim 5, comprising the following steps after the addition of FDA: (i) stirring the reaction mixture at about room temperature for at least 20 minutes; (ii) heating the reaction mixture at a temperature comprised between 30°C and reflux temperature and stirring for a time between 12 to 48 hours; (iii) cooling the reaction mixture at about room temperature and diluting with a solvent selected from the group consisting of methanol, ethanol, isopropanol, water and dichloroethane; and (iv) washing with water until the pH becomes neutral and drying. 7. The method according to any of claims 1 to 6, wherein the catalyst is FeCl3. 8. The method according to any of claims 1 to 7, wherein the aprotic organic solvent is dichloroethane (DCE). 9. The method according to any of claims 1 to 8, wherein the monomer of formula (I) is tetraphenylmethane. 10. A gas-adsorbing porous organic polymer having the general formula (II): formula (II) wherein A, B, C, D and E are as defined in claim 1 and n is a integer, characterized in that it comprises ultramicropores having pore size lower than 7 Angstrom (A). 11. The gas-adsorbing porous organic polymer according to claim 10, wherein A is a carbon atom and each of B, C, D and E is a monovalent radical of benzene. 12. The gas-adsorbing porous organic polymer according to claim 10 or 11, comprising a porous volume of ultramicropores of 0.5 to 3 cm /g, the ultramicropores having pore size lower than 7 Angstrom (A). 13. The gas-adsorbing porous organic polymer according to any of claims 10 to 12, further comprising micropores having a pore size of between 7 and 20 Angstrom (A), preferably of about 8, 12 and 16 Angstrom (A). 14. A method of storing a gas,, characterized in that the gas is stored using a gas- adsorbing porous organic polymer according to any of claims 10 to 13. 15. The method according to claim 14, wherein the gas is selected from the group consisting of hydrogen, methane and carbon dioxide. |
The present invention relates to a gas-adsorbing porous organic polymer, particularly hydrogen, methane and carbon dioxide, as well as to the method of preparing thereof and to its use for storing gas.
The continuous increase in world demand for energy which occurred during the last decades, together with concerns about climate changes arising from carbon dioxide emissions associated with the use of coal, determined an acceleration of the efforts to facilitate the development and use of new energy technologies based on alternative sources, such as natural gas and hydrogen. There is therefore a strong interest in the development of new porous materials characterized by appropriate surface area and by micrometer pore size, which would be not only useful for optimal gas storage for energy and environmental applications, but also for applications in different fields such as molecular separations and catalysis.
Gas-adsorbing porous organic polymers are disclosed in the prior art. For example, a carbon dioxide (C0 2 ) -adsorbing microporous polymeric material , which is synthesized by cross-linking tetraphenylmethane with formaldehyde dimethyl acetal (FDA) in the presence of FeCl 3 , is described in Dawson R. et al. Energy Environ. Sci. , 2011, 4, 4239-
4245. The crystalline polymeric material thereby obtained, which in the following will by designated as "Polymer E" - is characterized by the presence of micro- and mesopores with sizes which do not render them particularly suitable for adsorbing hydrogen and methane.
A porous polymeric material capable of adsorbing and storing both carbon dioxide (C0 2 ) and hydrogen (H 2 ) as well as methane (CH 4 ) is the so-called PAF- 1 (porous aromatic frameworks). Its synthesis is described in Teng Ben et al., Angew. Chem. Int. Ed. 2009, 48, 9457-9460. Although also PAF- 1 is synthesized starting from brominated tetraphenylmethane as the monomer, it chemically differs from the above-mentioned
Polymer E in that its aromatic rings are directly linked with each other, while in Polymer E the aromatic rings are linked with each other through methylene groups (-CH 2 -). Although PAF- 1 is provided with optimal hydrogen, methane and carbon dioxide adsorbing properties as well as with a high surface area and good thermal and hydrothermal stability, it has remarkable economical and industrial disadvantages which are due to the fact that its method of synthesis is expensive and difficult to scale-up.
The present invention has the object of overcoming the drawbacks of the prior art.
In particular, one object of the present invention is to provide a porous organic polymer which, on the one hand, is capable of effectively adsorbing and storing gases such as carbon dioxide, hydrogen and methane and, on the other hand, is capable of being prepared by a method which makes use of consumer reagents and which is simple, cost-effective and easy to scale-up.
These and other objects are achieved by the method of preparing a gas-adsorbing porous organic polymer as defined in appended claim 1.
The scope of the present invention also includes the use of the gas-adsorbing porous organic polymer according to the invention in a method of storing gas as defined in appended claim 14. The dependent claims define further features of the method and polymer of the invention and form an integral part of the description.
As it will be illustrated in more detail in the following, the gas-adsorbing porous organic polymer obtainable by the method of the invention contains a remarkable amount of ultramicropores which, thanks to their size, are particularly suitable for adsorbing and storing hydrogen and methane gases, without having a particularly high surface area.
Furthermore, such polymer is obtainable by a preparation method which makes use of consumer solvents and catalysts and which therefore is neither extremely expensive nor particularly difficult to scale-up. Further objectives, features and advantages will become apparent from the following detailed description. However, the detailed description and the specific examples, although indicating preferred embodiments of the invention, are provided by way of illustration only, since after their reading various changes and modifications which are comprised within the spirit and scope of the invention will become apparent to the person skilled in the art. The preparation method of the invention consists essentially in a Friedel-Crafts reaction using a Friedel-Crafts catalyst, a tetrahedral monomer of general formula (I) as defined in the following, and formaldehyde dimethyl acetal (FDA) as the cross-linking agent.
An essential feature of the method of the invention is that the molar ratio of the monomer of formula (I) to FDA should be comprised within the range of from 1 :9 to 1 :30. The present inventors in fact observed that said molar ratio of the monomer of formula (I) to FDA unexpectedly results in a polymeric material which is provided with porosity features (in particular relating to the pore size and pore volume) which make it capable of effectively adsorbing and storing hydrogen and methane in addition to carbon dioxide. A particularly preferred value of the molar ratio of the monomer of formula (I) to FDA is of about 1 : 16.
The tetrahedral monomers which are employed in the preparation method of the invention have the formula (I) illustrated herein below:
B
E A C
formula (I)
wherein A is selected from a C atom, a Si atom, a Ge atom, a Sn atom, an adamantane group, an ethane group and an ethene group,
Adamantane Ethane Ethene and wherein each of B, C, D and E is a 6-membered ring structure selected from the monovalent radicals of the compounds benzene, naphtalene, anthracene, phenanthrene, pyrene, optionally having one or more substituents selected from nitro, amino, hydroxyl, sulfonyl, halogen, phenyl, alkyl, haloalkyl, hydroxyalkyl, aminoalkyl, aryl, alkenyl and alkynyl groups.
In the formula (I) illustrated above, a halogen which is preferred as an optional substituent is fluorine; preferred alkyls as optional substituents are methyl, ethy, propyls, butyls; preferred haloalkyls as optional substituents are chloromethyl, chloroethyl; preferred hydroxyalkyls as optional substituents are hydroxymethyl, hydroxyethyl; preferred aminoalkyls as optional substituents are aminomethyl, aminoethyl; preferred aryls as optional substituents are benzene, toluene, phenol, aniline, acetophenone, benzaldehyde, benzoic acid, o-xylene, m- xylene, p-xylene, benzonitrile, biphenyl; preferred alkenyls as optional substituents are ethenyl, propenyl, 1-methylethenyl, butenyl.
A preferred tetrahedral monomer for use in the method of the invention is a compound of formula (I) wherein each of the ring structures A, B, C, D and E is a monovalent radical of benzene optionally having one or more substituents as defined above. A particularly preferred tetrahedral monomer is tetraphenylmethane, wherein A is a carbon atom and each of A, B, C, D and E is an unsubstituted monovalent radical of benzene, that is to say a phenyl radical.
Examples of Friedel-Crafts catalysts suitable for use in the preparation method of the invention are BF 3 , BeCl 2 , TiCl 4 , SbCl 5 , SnCl 4 , FeCl 3 , A1C1 3 , Sc(OTf) 3 , Mo(CO) 6 , SeCl 4 , TeCl 4 , sulfuric acid, hydrofluoric acid and superacids, such as for example HF SbF or
HS0 3 F SbFs. The most preferred catalyst is FeCl 3 .
Aprotic organic solvents suitable for use in the method of the invention include both polar and non-polar solvents. Specific examples of solvents, provided by way of illustration only, are dichloroethane, toluene, benzene, nitromethane (CH 3 N0 2 ), carbon disulfide and chlorobenzene. The most preferred solvent is dichloroethane. As mentioned above, the present inventors observed that by using a molar ratio of the monomer of formula (I) to FDA comprised within the range of from 1 :9 to 1 :30, a porous polymeric material is obtained which clearly differs from the prior art Polymer E in both the porosity and the structure, although they have the same chemical formula.
Actually, the porous organic polymer of the present invention is characterized in that it has two pore families: the ultramicropore family and the micropore or supermicropore family. Such terms are used in the present description according to the meaning given to them by the IUPAC, which has classified the pores in three main categories based on their size: the macropores, having a pore size higher than 50 nm (500 A); the mesopores, having a pore size from 20 to 500 A; the micropores, having a pore size lower than 20 A. The micropores are in turn classified into two groups, i.e. the ultramicropore s (lower than 7 A) and the supermicropores (from 7 to 20 A). Differently from the porous organic polymer of the present invention, the prior art Polymer E is completely devoid of ultramicropores. As mentioned above, such difference is extremely important for the functionality of the porous organic polymer of the invention, in that thanks to that feature it is particularly suitable to adsorb and store gases such as hydrogen and methane.
A further difference between the porous organic polymer of the invention and the prior art Polymer E is that the former is amorphous in structure while the latter is crystalline.
A more detailed description of the structural features and the porosity of the porous organic polymer of the present invention, made with reference to the preferred embodiment thereof in which the tetrahedral monomer of formula (I) is tetraphenylmethane, is provided in the following example. The example is illustrative only and it does not limit the scope of the invention as defined in the appended claims.
EXAMPLE
All chemicals were purchased either from Sigma Aldrich Co. or from Alfa Aesar GmbH & Co and were used without further purification unless otherwise stated. Synthesis with conventional heating
A gas-adsorbing porous organic polymer falling within the scope of the present invention, wherein the tetrahedral monomer of formula (I) is tetraphenylmethane, was synthesized as follows.
Ferric chloride (25.95 g 0.16 mol) and tetraphenylmethane (TPM 3.20 g, 0.01 mol) were suspended in dichloroethane (DCE, 240 mL). The resulting mixture was vigorously stirred at room temperature to obtain a clear solution, then formaldehyde dimethylacetal (FDA, 12.17 g, 0.16 mol) was added dropwise. The resulting thick gel was stirred at room temperature for 4 hours and then heated to reflux for 17 hours. After cooling to room temperature, the gel was diluted with methanol and washed several times with water until the pH become neutral, and finally dried in an oven at 100 °C overnight. The polymer thereby obtained is designated as "UPO-1".
The same synthetic procedure was used on other precursors, that are reported in Table 1 together with the UPO polymers obtained and the amounts used.
Table 1
The same synthesis procedure was also performed with precursonFDA ratios of 1:9 and 1:30, varying the FeCl 3 :FDA ratio from 1: 10 to 2: 1.
The synthesis of the UPO polymers reported in Table 1 was also performed by using unconventional heating methods, i.e. microwave synthesis, autoclave synthesis, and ultrasonic synthesis.
Microwave synthesis
The same amounts of ferric chloride and precursor in dichloroethane as indicated above were put into a schlenk. The mixture was stirred for 4 minutes and the FDA was added over 4 minutes. Then, the mixture was stirred for 2 minutes, after which the schlenk was put into a microwave oven (80W power) and the reaction was started with stirring and cooling in order to maintain a constant temperature of 80°C. The reaction time was of 60 minutes. Washing was performed as described in the previous paragraph concerning the synthesis with conventional heating s
Equivalent results were obtained by varying the reaction conditions within the ranges indie ated below :
Power: 1-300 W
Temperature: 25- 150°C
Time prior to ramp temperature: 1- 120 minutes
Reaction time: 1-240 minutes
Autoclave synthesis
The same amounts of ferric chloride and precursor in dichloroethane and FDA as indicated above were put into a autoclave under the following conditions: temperature = 120 °C; autogenic pressure; reaction time: 6 hours. The reaction was carried out both with and without a stirring system.
Equivalent results were obtained by varying the reaction conditions within the ranges indicated below:
Temperature: 10-240°C
Time: 30 minutes - 7 days As an alternative, FDA can be progressively added over 1-120 minutes to the TPM, FeCl 3 and DCE mixture in autoclave. The reaction is carried out under the same reaction conditions as indicated above. Ultrasonic synthesis
The same amounts of ferric chloride and precursor in dichloroethane as indicated above were put into a flask. The mixture was stirred for 15 minutes and FDA was added over 15 minutes. The resulting mixture was stirred for 4 hours. These stirring times can be varied between 1 and 120 minutes and between 1 minute and 12 hours after the addition of FDA. In order to start the reaction, the flask was placed in a ultrasonic bath or sonicated with a ultrasonic immersion probe and the following reaction conditions were applied: 60 W potency, 40 KHz frequency, 80 °C temperature, 60 minutes reaction time. Washing was performed as described previously.
Equivalent results were obtained by varying the reaction conditions within the ranges indicated below:
Power: 20-150 W
Frequency: 5-60 KHz
Temperature: 25- 150°C
Reaction time: 1-360 minutes
Characterization methodologies N 2 physisorption measurements were carried out at 77K in the relative pressure range from
1 x 10 " to 1 P/Po by using a Quantachrome AutosorblMP/TCD instrument. Prior to analysis, the samples were outgassed at 150 °C for 16 hours (residual pressure lower than 10 "6 Torr). Specific surface areas were determined using the Brunauer-Emmett-Teller (BET) equation, in the relative pressure range from 0.05 to 0.15 P/Po- Pore size distributions were obtained by applying the NLDFT method at the equilibrium and using a carbon kernel based on a slit pore model. Solid-state NMR spectra were acquired on a Bruker Advance III 500 spectrometer
13 equipped with a wide bore 11.7 Tesla magnet and operating at 125.75 MHz for C and at 500.13 MHz for 1H. 1H- 13 C cross polarization magic angle spinning (CP-MAS) experiments were carried out.
Adsorption/desorption of methane were performed between 0 and 10 atm at 273 K with a Micrometrics ASAP 2050 - Xtended Pressure instrument.
Adsorption/desorption of hydrogen were performed between 0 and 100 atm at 77 K with a Gas Reaction Controller-PCI Unit instrument (Advanced Materials Corporation).
X-ray diffractograms (XRD) were recorded on unoriented ground powders with a Thermo ARL 'XTRA-048 diffractometer with a Cu Ka (k = 1.54 A °) radiation. Thermogravimetic analyses were performed on a Setaram SETSYS Evolution instrument under argon (gas flow 20 mL/ min), heating the samples up to 1173 K with a rate of 5 K/min,
SEM images at different magnification were recorded on a Quanta 200 FEI Scanning Electron Microscope equipped with ED AX EDS attachment, using a tungsten filament as the electron source at 20 KeV.
Comparative results By comparing the characterization data of Polymer E which are reported in Dawson R. et al. Energy Environ. Sci. , 2011, 4, 4239-4245 with the characterizations made by the present inventors on the UPO-1 polymer, the following differences which relate to both the porosity and the structure of the materials were detected. First, UPO- 1 is characterized in that it has different pore families (which are the most valued for ¾ and CH 4 storage): the ultramicropore family at 5.5 A (with a differential pore volume of about 2,8 cm /g), which is totally absent from Polymer E, and the 8, 12 and 16 A micropore families, which in Polymer E are shifted at 10, 17 and 22 A. Furthermore, the quantity of micropores is different: UPO-1 has a differential pore volume of about 0.7
3 ° 3 °
cm /g for the micropores at 8 A , about 1.6 cm /g for micropores at 12 A and about 1 cm 3 /g for those at 16 A ° .. Instead, Polymer E is characterized by a maximum of 0.9 cm 3 /g o 3 °
for the 10 A micropores and of 1,1 cm /g for the 17 A micropores.
Table 2. Comparison between the differential pore volume of various pore families in UPO-1 and Polymer E.
The different pore size distribution and the different N 2 adsorption/desorption properties are illustrated in figure 1. The upper panels show the N 2 adsorption/desorption isotherms at 77K, and the lower panels show the pore size NL-DFT distributions, with reference to both the prior art Polymer E (left) and the UPO-1 polymer of the invention (right).
Another characterization which clearly distinguishes the UPO-1 polymer from Polymer E is the X-ray powder diffraction (XRD) analysis. The XRD data indicate that UPO-1 is totally amorphous (figure 2, right panel), while Polymer E has a crystalline structure (figure 2, left panel).
Nitrogen physisorption isotherms and powder diffraction XRD analysis were also made for UPO polymers reported in Table 1 (Figure 3).
In Figure 3, the upper panels show the adsorption isotherms (right) and the pore distributions (left). The adsorption/desorption isotherms have different form and hysteresis loops due to the different geometries of pores obtained from different precursors. The apparent BET surface areas for the networks are shown in Table 3. The pore size distributions are also different, nevertheless all the materials show the presence of a family of ultramicropores centered at about 5.5 A and micropores between 12 and 14 A.
Table 3. BET surface areas of the synthesized UPO polymers
The Powder X-ray diffraction of the UPO samples reported in Figure 3 (lower panel) confirms the formation of amorphous materials, showing the absence of long-range structural order for all the samples and no evidence for characteristic reflections from a crystalline phase. The X-Ray pattern diffraction of the UPO-4 material shows some signal reflections on the amorphous band, due to the adamantane "cage" that is maintained in the polymeric structure; the comparison between the tetraphenyladamantane monomer and the UPO-4 polymer is reported in Figure 4 to highlight that the reflections present in the polymer are due to the presence of the adamantane group.
CH4 and F storage: comparison between UPO-1 and PAF-1
The two tables which are provided herein below show the comparison between the hydrogen and methane storage abilities of the UPO-1 polymer of the present invention and one of the prior art polymers having the highest surface area, i.e. the PAF-1 polymer, in which the aromatic rings of tetraphenylmethane are directly linked with each other.
Table 4. Comparison between the H 2 storage ability of UPO-1 and PAF-1 at high pressures Polymer SSA (m 2 /g) T (K) P (bar) Wt% Kg/L
UPO-1 (d= 0.6 g/mL) 1320 77 48 4.08 0.0245
PAF-1 (d= 0.3 g/mL) 5600 77 48 10.70 0.0321
The data relating to PAF- 1 reported in Table 4 are taken from Teng Ben et al., Angew. Chem. Int. Ed. 2009, 48, 9457 -9460.
Table 5. Comparison between the CH 4 storage ability of UPO-1 and PAF- 1 at low pressures
The data relating to PAF- 1 reported in Table 5 are taken from Teng Ben et al. Energy Environ. Sci. 2011, 4, 3991-3999.
As can be seen in the tables 4 and 5,UPO-l has a high pressure hydrogen storage ability and low pressure methane storage ability which are substantially comparable to those of PAF- 1. This is an unexpected result, in that the surface area (SSA) of UPO-1 is 1321 m7g while the surface area of PAF- 1 is 5600 m7g.
This result is related to the presence of ultramicropores in UPO- 1 material, subject of this claim. The comparison of the volumetric capacities (Kg/L) of methane storage (column 6 of Table 5) is particularly interesting as these values are much higher (about 2.4 times) in UPO-1 than in PAF- 1 because of the greater density of UPO-1. This result is particularly relevant for gas storage technological applications.
Table 6. H 2 and CH 4 storage ability of UPO- 1 at high pressures and room temperature (for H 2 also a 77 K). T (K) P [bar] wt% Kg/L
H 2 298 100 1.5 0.0090
H 2 77 100 6.0 0.0360
5
CH 4 298 100 18.65 0.1119
These H 2 and CH 4 storage data of UPO-1 at 100 bar (Table 6) cannot be compared with PAF-1 because of the absence of corresponding values at these temperature and pressure conditions. The values obtained with UPO-1 confirm its high H 2 and CH 4 storage ability also at room temperature.
Next Patent: PROVISIONING PAYMENT CREDENTIALS TO A CONSUMER