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Title:
ULTRAPOROUS METAL ORGANIC FRAMEWORK MATERIALS AND METHOD FOR THEIR PRODUCTION
Document Type and Number:
WIPO Patent Application WO/2014/122105
Kind Code:
A1
Abstract:
The present invention refers to a new ultraporous metal-organic framework material with increased surface area, a process for its preparation using an aqueous microemulsion of alkylamines, as well as its use as adsorbent, desiccant, flame retardant, storage material, gas purificator, selective capturer, drug delivery material, depot material for active substances or catalysts.

Inventors:
CASTILLO GARCÍA OSCAR (ES)
BEOBIDE PACHECO GARIKOITZ (ES)
LANCHAS GONZÁLEZ MÓNICA (ES)
LUQUE ARREBOLA ANTONIO (ES)
ROMÁN POLO PASCUAL (ES)
PÉREZ YÁÑEZ SONIA (ES)
Application Number:
PCT/EP2014/052084
Publication Date:
August 14, 2014
Filing Date:
February 04, 2014
Export Citation:
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Assignee:
UNIV DEL PAÍS VASCO (ES)
International Classes:
B01J20/22; B01J20/28; C01B3/00; C07F15/06
Other References:
ZHIFENG XIN ET AL: "Synthesis and Enhanced H2 Adsorption Properties of a Mesoporous Nanocrystal of MOF-5: Controlling Nano-/Mesostructures of MOFs To Improve Their H2 Heat of Adsorption", CHEMISTRY - A EUROPEAN JOURNAL, vol. 16, no. 44, 13 October 2010 (2010-10-13), pages 13049 - 13052, XP055070492, ISSN: 0947-6539, DOI: 10.1002/chem.201001700
OMAR K. FARHA ET AL: "Metal-Organic Framework Materials with Ultrahigh Surface Areas: Is the Sky the Limit?", JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, vol. 134, no. 36, 20 August 2012 (2012-08-20), pages 15016 - 15021, XP055070443, ISSN: 0002-7863, DOI: 10.1021/ja3055639
YUN-QI TIAN ET AL: "Cadmium Imidazolate Frameworks with Polymorphism, High Thermal Stability, and a Large Surface Area", CHEMISTRY - A EUROPEAN JOURNAL, vol. 16, no. 4, 23 December 2009 (2009-12-23), pages 1137 - 1141, XP055070544, ISSN: 0947-6539, DOI: 10.1002/chem.200902729
0. K. FARHA ET AL., JACS, vol. 134, 2012, pages 15016
K. SUMIDA ET AL., CHEM. REV., vol. 112, 2012, pages 724
XIN, Z. ET AL., CHEM. EUR. J., vol. 16, 2010, pages 13049 - 13052
FARHA, O. ET AL., J.A.CS., vol. 134, 2012, pages 15016 - 15021
YUN-QI TIAN ET AL., CHEM. EUR. J., vol. 16, 2010, pages 1137 - 1141
K. M. CHOI ET AL., J. AM. CHEM. SOC., vol. 133, 2011, pages 11920
L. G. QIU ET AL., ANGEW. CHEM., INT. ED., vol. 47, 2008, pages 9487
J. G6RKA ET AL., CHEM. COMMUN., vol. 46, 2010, pages 6798
X. D. DO ET AL., MICROPOROUS MESOPOROUS MATER., vol. 141, 2011, pages 135
X. ROY; M. J. MACLACHLAN, CHEM. EUR. J, vol. 15, 2009, pages 6552
S. PEREZ-YANEZ ET AL., CHEM. COMMUN., vol. 48, 2012, pages 907
PURE APPL. CHEM ., vol. 45, 1976, pages 71 - 79
M. LANCHAS ET AL., CHEM. COMMUN., vol. 48, 2012, pages 9930
Attorney, Agent or Firm:
FERNÁNDEZ ARIZPE, Almudena (S.LEdificio Euromo, Avenida de Burgos 16D Madrid, ES)
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Claims:
A process for the preparation of an ultraporous metal-organic framework material, said process comprising: a) preparing an aqueous microemulsion comprising an alkyl amine of formula (I):

(I)

wherein:

R1 is a substituted or unsubstituted alkyl radical having from 4 to 12 carbon atoms; and

R2 and R3 are each independently a hydrogen atom or an alkyl radical having from 1 to 12 carbon atoms. b) preparing an aqueous solution comprising: b. l .) a precursor of a metal ion, and b.2.) an organic compound having at least two atoms capable of coordinating to metal ions; c) mixing the aqueous microemulsion obtained in step a) and the aqueous solution obtained in step b), thus forming a precipitate containing micelles of alkylamines of formula (I); and d) subjecting the precipitate obtained in step c) to a heating process at a temperature ranging from 50 to 250°C during at least one hour to remove the micelles of alkylamines of formula (I).

The process according to claim 1 , wherein the precursor of the metal ion is an inorganic salt, an oxide, a hydroxide, the salt of an inorganic oxygen-containing acid, an organic salt, optionally in the form of a hydrate or a mixture thereof or the metal in its elemental form..

3. The process according to any one of claims 1 and 2, wherein the organic compound capable of coordinating to metal ions is a heteroaromatic compound having at least two nitrogen atoms, wherein said heteroaromatic compound is unsubst itiited or has one or more substituents independently selected from C1 -6 alkyl, NIT, NH(C, alkyl), N(Ci„6 alkyl)2, Oi l, =0, O-C, (> alkyl, halogen, cyano and nitro.

4. The process according to any one of claims 1 to 3, which further comprises the isolation of the precipitate obtained in step c).

5. The process according to any one of claims 1 to 4, wherein step d) is assisted by vacuum.

6. An ultraporous metal-organic framework material obtainable by the process as defined in any of claims 1 to 5.

7. The ultraporous metal-organic framework material as defined in claim. 6, having a BET surface area higher than 3000 m2/g and micropores with diameters of less than 2 nm, said material comprising repeating units comprising a metal ion and an organic linking moiety, characterized in that said material comprises additional pores resulting from the removal of the micelles of aikylamines of formula (I) in step d), said additional pores being homogeneously distributed within the framework material and having a diameter from 0.5 to 4 nm.

8. The ultraporous framework material according to claim. 7, wherein the BET surface area is higher than 4000 m2/g.

9. The ultraporous framework material according to any one of claims 7 and 8, wherein the additional pores have a diameter from 0.5 to 2.5 nm.

10. The ultraporous framework material according to any one of claims 7 to 9, wherein the metal ion is an ion of an clement selected from Zn, Fe, Mn, Cu, Ni, Al, Be or Co.

1 1 . The ultraporous framework material according to any one of claims 7 to 1 0, wherein the organic linking moiety is a heteroaromat ic compound having at least two nitrogen atoms, wherein said heteroaromatic compound is unsubstituted or has one or more substituents independently selected from Ci_6 alkyl, NH2, NH(C i (, alkyl), N(Ci„6 alkyl)2, OH, =0, O-C'i (, alkyl, halogen, cyano and nitro.

12. A metal-organic framework material having micropores with diameters of less than 2 nm., said material comprising repeating units comprising a metal ion and an organic linking moiety, characterized in that said material further comprises micelles of alkylamines homogeneously distributed within the framework material, wherein said alkylamines have the general formula (I):

(I) wherein:

R 1 is a substituted or unsubstituted, linear or branched, alkyl radical having from 4 to 12 carbon atoms; and

R2 and R3 are each independently a hydrogen atom or a linear or branched alkyl radical hav ing from 1 to 12 carbon atoms.

13. The framework material according to claim 12, wherein the alkylamine of formula (I) is a monoalkylamine of formula NHhR1 , wherein R 1 is an unsubstituted linear alkyl radical hav ing from 4 to 8 carbon atoms.

14. The framework material according to any one of claims 12 to 13, wherein the metal io is an ion of an element selected from Zn, Fe, Mn, Cu, Ni, Al, Be or Co.

15. The framework material according to any one of claims 12 to 14, wherein the organic l inking moiety is a heteroaromatic compound having at least two nitrogen atoms, wherein said heteroaromatic compound is unsubstituted or has one or more substituents independently selected from d_6 alkyl, NH2, NH( i <, alkyl ), N(Ci„6 alkyl)2, Oi l. =0, O-C' i <, alkyl, halogen, cyano and nitro.

16. Use of an uitraporous metal-organic framework material as defined in any of claims 6 to 1 1 as adsorbent, desiccant, flame retardant, storage material, gas purifier, selective capturer, drug delivery material, depot material for active substances or catalysts.

Description:
ULTRA POROUS METAL ORGANIC FRAMEWORK MATERIALS AND METHOD FOR THEIR PRODUCTION

FIELD OF THE INVENTION

The present invention relates to novel ultra porous metal-organic framework materials, process for preparing thereof and their use as adsorbents, desiccants. flame retardant storage materials or depot materials for active substances or catalysts.

BACKGROUND Ultraporous materials (defined as those with surface area above 3000 rrf/g) are of general interest in industrial applications such as gas storage, capture and separation, selective catalysis (size/shape), drug storage and delivery and sensoring. Emerging areas such as the C0 2 capture and valorisation, H 2 and light hydrocarbons storage at mild conditions (pressure and temperature) require the continuous development of new materials with high performance and competitive prices. For instance, nowadays the C0 2 capture is highly demanded for integrated gasification combined cycle centrals (IGCC) and for the purification of the H 2 stream produced by means of the gasification of the biomass or fuels. Related with the latter issue, the removal of poisoning impurities such as CO from the H 2 source is crucial in the fields of catalytic hydrogenation and H 2 fuel-cells. Other relevant aspects concerning the Kyoto requirements are the development of zero-emission hydrogen vehicles and the greenhouse or CFCs gases capture from the industrial emissions.

MOFs (Metal-Organic Frameworks) stand out among the different porous materials because they hold the current surface area record (-7200 m 2 /g, approximately the surface area of one and a half football fields) with a large difference over zeolites or activated carbon [O. K. Farha et al, JACS, 2012, 134, 15016].

Even though the most widely used materials up until today have been zeolites or activated carbon due to their low cost and to the long-standing tradition of using them, new technological needs require more efficient materials. In this aspect, state-of-the-art technological prototypes incorporating these MOFs materials as the core of their operation are emerging today. To mention a unique example, Mercedes-Benz has created a car prototype (F125) equipped with a tank filled with MOFs for storing H 2 (ca. 7.5 kg) necessary for engine operation. Around the same time, BASF has demonstrated an endurance of 45,000 km for a light-weight vehicle prototype equipped with a fuel tank filled with MOFs for storing methane as fuel. On the other hand, MOFs have demonstrated an exceptional applicability for C0 2 capture and sequestration (CCS) technologies, where C0 2 capture in porous materials has greater energy efficiency compared with the methods existing up until now [K. Sumida et al, Chem. Rev. 2012, 112, 724]. MOFs are considered to be porous coordination polymers consisting of a combination of metal ions as nodes and organic bridging ligands as connectors that extends into the three dimensions.

Xin, Z. et al. [Chem. Eur. J, 2010, 16, 13049-13052] describes the synthesis of a mesoporous nanocube of MOF-5 with improved H 2 heat of adsorption and also improved H 2 , C0 2 and CH 4 uptake, having a BET surface area of 3243 cm 2 /g. The structure of this material consists of a combination of zinc as metal ion and benzendicarboxylic acid as organic bridging ligand with mesopores ranging from 1.7 and 300 nm. The process for its preparation includes the mixture of 1,4- benzenedicarboxylic acid and zinc nitrate hexahydrate and requires the use of DMF as solvent which is rather difficult to evacuate.

Farha, O. et al. [J.A.C.S., 2012, 134, 15016-15021] reports the synthesis of metal- organic frameworks having a BET surface area about 7000 m 2 /g with a bimodal pore size distribution, and which are obtained by solvothermal reactions of hexacarboxylated linkers and cupper nitrate using a mixture of DMF ethanol and hydrogen chloride as solvents. In order to remove solvent molecules from the pores without significantly diminishing the porosity, the material is activated with supercritical carbon dioxide.

Yun-Qi Tian et al. [Chem. Eur. J, 2010, 16, 1137-1141] discloses a metal-organic framework material with Langmuir surface area of 3010 m 2 /g and pore diameters of 9 and 9.6 A, comprising cadmium ions and 2-nitroimidazole as organic linking moiety, which are obtained by solvothermal reaction using DMF, DMA or NMP as organic solvents. Despite such high surface area values reported in these documents, ultraporous MOFs suffer a series of drawbacks for their industrial-scale production and application:

1. The molecules binding the metallic cores to one another and therefore providing cohesion to the three-dimensional framework are complex, difficult to produce and therefore costly.

2. Complex synthesis making the production thereof more expensive (solvo thermal conditions requiring leak-tight reactors that withstand high temperature and pressure, as well as hazardous organic solvents such as DMF, DEF... which furthermore partially decompose during synthesis, making reusing them difficult).

3. Activating the material, i.e., removing the molecules present in the pores, is complex and these ultraporous materials usually require the use of supercritical drying conditions with C0 2 , which adds additional complexity to the process and makes it more expensive. Different attempts have been made to modify or improve the porosity of MOFs. Today, only a few of these attempts are based on the template effect, a well-known synthesis concept which allows introducing mesoporosity into a material.

For instance, endotemplate pathways are utilized in the synthesis of mesoporous silica phases (MCMs, SB As...), while exotemplates are employed for mesoporous carbons (CMKs, KITs...) and for other ceramics.

The incorporation of micelles during the material forming process is a method that results in new pores after removing the molecules present in these micelles. Only very recently a few examples that extrapolate this methodology to the synthesis of MOFs have began to emerge [K. M. Choi et al, J. Am. Chem. Soc, 2011, 133, 11920; L. G. Qiu et al, Angew. Chem., Int. Ed., 2008, 47, 9487; J. Gorka et al, Chem. Commun., 2010, 46, 6798; X. D. Do et al, Microporous Mesoporous Mater., 2011, 141, 135; X. Roy and M. J. MacLachlan, Chem. Eur. J, 2009, 15, 6552]. However, all these attempts use surfactants with long aliphatic chains which put the resulting micelles, and therefore the pores they generate, within the mesoporous range (> 2 nm), thus lowering the contribution of the microporosity to the total porosity with respect to the starting material and decreasing the accessible total surface area. There is a publication [S. Perez- Yanez et al, Chem. Commun., 2012, 48, 907] where butanoic acid has been used as a surfactant for obtaining small micelles with a diameter less than 2 nm which have enabled converting a barely porous material (210 m 2 /g) into a moderately porous material (428 m 2 /g). This method is limited to the compound in question because butanoic acid is one of the components of the actual MOF so it can be readily incorporated into the synthesis process. In other cases, this method is unworkable since the presence of the acid prevents or hinders the necessary deprotonation of the connecting molecule so that said molecule can bind the metallic cores. In view of the disadvantages conferred by the currently available ultraporous metal organic frameworks materials and the processes for their preparation, it is desirable to develop new ultraporous materials with improved properties, in particular improved porosity, which try to solve the problems mentioned above, and which can be produced by means of a cost-effective procedure.

BRIEF DESCRIPTION OF THE INVENTION

The authors of the present invention have developed a new process for the preparation o ultraporous metal-organic framework materials with an increased porosity and a surface area higher than 3000 m 2 /g, based on the use o aqueous synthetic routes and cheap building blocks with synthesis temperatures ranging from 0 to 80°C, thus providing a procedure economically advantageous, which can be applied at industrial scale.

The key factor for the success of the process of the invention is the use of small alkylamines surfactant molecules that provide stable microemulsions containing micelles when mixed with the water. The incorporation of micelles of alkylamines during the synthesis of the metal-organic framework material and its subsequent activation provides it with additional pores to those presented by the material synthesized in the absence of said alkylamines. In particular, these additional pores have diameters ranging from. 0.5 to 4 nm. Moreover, the incorporation of said alkylamines increases the BET surface area between 1 .5 to 5 times the maximum reported v alue for a material synthesized in the absence of said alkylamines, as well as the theoretical surface area based on the crystal structure of the material, in contrast to the state of the art wherein the incorporation of micelles leads to the loss o surface area.

A.s a consequence of that, the total pore volume of the material is also increased, thus improving the properties of these framework materials to be used in many applications, for example, as adsorbents, desiccants, flame retardants, storage materials or depot materials for active substances or catalysts.

Therefore, a first aspect of the present invention refers to a process for the preparation of an ultraporous metal-organic framework material, said process comprising: a) preparing an aqueous microemulsion comprising an alkylaminc of formula

(I):

(I) wherein:

R 1 is a substituted or unsubstituted aikyl radical having from 4 to 12 carbon atoms; and

R and R 3 are each independently a hydrogen atom or an alky! radical having from 1 to 1 2 carbon atoms. preparing an aqueous solution comprising: b.1.) a precursor of a metal ion, and b.2.) an organic compound having at least two atoms capable of coordinat ing to metal ions: mixing the aqueous microemulsion obtained in step a) and the aqueous solution obtained in step b), thus forming a precipitate containing micelles of alkylamines of formula (I); d) subjecting the precipitate obtained in step c) to a heating process at a temperature ranging from. 50 to 2 0"C during at least one hour to remove the micelles of alkyiamines of formula (I).

In another aspect, the present invent ion refers to an ultra porous metal-organ ic framework material obtainable by the process as defined above.

This material has a BET surface area higher than 3000 m 2 /g and micropores with diameters of less than 2 nm, and comprises repeating units comprising a metal ion and an organic linking moiety, characterized in that said material comprises additional pores resulting from the removal of the micelles of aikyl amines in step d) of the process of the invention, said addit ional pores being homogeneously distributed within the framework material and having a diameter from 0.5 to 4 nm.

Another aspect of the invention refers to an intermediate in the synthesis of the uitraporous metal-organic framework of the invention and which corresponds to the precipitate obtained after conducting step c) of the process of the invention. This precipitates is also a metal organic framework material having micropores with diameters of less than 2 nm, said material comprising repeating units comprising a metal ion and an organic linking moiety, characterized in that said material further comprises micelles of alkyiamines homogeneously distributed within the framework material, wherein said alkyiamines have the general formula (I):

(I) wherein:

R 1 is a substituted or unsubstituted, linear or branched, alkyl radical having from 4 to

12 carbon atoms; and

R 2 and R 3 are each independent ly a hydrogen atom or a linear or branched alkyl radical having from 1 to 12 carbon atoms. Finally, another aspect of the invention relates to the use of an ultraporous metal- organic framework material as defined above as adsorbent, desiccant, flame retardant, storage material or depot material for active substances or catalysts.

DETAILED DESCRIPTION OF THE INVENTION

As used herein and in the appended claims, the singular forms "a," and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "a pore" includes a plurality of such pore and reference to "the metal" includes reference to one or more metals known to those skilled in the art, and so forth. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which this disclosure belongs. Although methods and materials similar or equivalent to those described herein can be used in the pract ice of the disclosed methods and composit ions, the exemplary methods, devices and materials are described herein. In the context of the present invention, the term "metal-organic framework" should be understood as a structure having repeating units comprising a metal ion and an organic linking moiety that extends into three dimensions. Therefore, a plural ity of said units l inked together defines the framework wherein the metal ion and the organic linking moiety are coordinat ively bound. Other terms usually employed in the scientific terminology to name metal-organic frameworks are: porous coordinated polymers, open-framework coordination polymers or complexes.

The term "ultraporous metal-organic framework material" refers to a metal-organic framework material as defined above having a BET surface area higher than 3000 m 2 /g. For the purpose of the present invention, the term "micropores" refers to pores hav ing a diameter of 2 nm or below in accordance with the definition in Pure Appl. Chem., 1976, 45, 71-79. The presence of micropores can be seen from the sorption measurements for determining the nitrogen uptake capacity of the metal-organic framework material at 77K. Hence, the typical isotherm, having the type I shape indicates the presence of micropores. A first aspect of the present invention refers to a process for the preparation of an ultraporous metal-organic framework material, said process comprising: a) preparing an aqueous microemulsion comprising an alkylamine of formula (I):

(I)

wherein:

R 1 is a substituted or unsubstituted a Iky I radical having from 4 to 12 carbon atoms; and

R : and R 3 are each independent ly a hydrogen atom or an a Iky I radical having from 1 to 12 carbon atoms. b) preparing an aqueous solut ion comprising: b.1.) a precursor of a metal ion, and b.2.) an organic compound hav ing at least two atoms capable of coordinating to metal ions; c) mixing the aqueous microemulsion obtained in step a) and the aqueous solution obtained in step b), thus forming a precipitate containing micelles of alkylamines of formula (I); d) subjecting the precipitate obtained in step c) to a heating process at a temperature ranging from 50 to 250"C during at least one hour to remove the micelles of alkylamines of formula (I).

In step a) of the process of the invention, a microemulsion comprising an alkylamine of formula (I) is prepared. Said microemulsion can be prepared by adding to an aqueous solvent an alkylamine of formula (I), this alkylamine acting as surfactant.

For the purpose of the present invention, an aqueous solvent means water or a mixture comprising at least 40% by weight of water, preferably at least 50% by weight, more preferably more than 50% by weight, based on the total amount of solvent. This aqueous solution is preferably a solution containing 100% of water as solvent.

In a preferred embodiment, R 1 in the alky lam ine of formula (I) is an unsubstituted linear alkyl radical having from 4 to 8 carbon atoms, such as, butyl, pentyi, hexyl, heptyl or octyl.

In another preferred embodiment, at least one of R and R 3 in the alkylamine of formula (I) is hydrogen, even more preferably both R and R 3 are hydrogen.

In a preferred embodiment, the alkylamine of formula (I) is a monoalky!amine of formula NH 2 R 1 , wherein R 1 is an unsubstituted linear alkyl radical having from 4 to 8 carbon atoms.

This step a) provides a microcmulsion comprising micelles of alkylamines dispersed in the aqueous solution, being the hydrophiiic part of the alkyl amine (amine group) in contact with the surrounding water, sequestering the hydrophobic tail regions (alkyl groups) in the centre of the micelle. In step b) of the process of the invention, an aqueous solution comprising a precursor of a metal ion and an organic compound having at least two atoms capable of coordinating to metal ions is prepared.

The solvent used in step b) is water or a mixture comprising at least 40% by weight of water, preferably at least 50% by weight, more preferably more than 50% by weight. based on the total amount of solvent. This aqueous solution is preferably a solution containing 100% of water as solvent.

In a part icular embodiment, when a mixture comprising at least 40% by weight of water is used, the other component is a solvent having unlimited miscibiiity with water, e.g. an alcohol. The precursor of the metal ion is preferably an inorganic salt, an oxide, a hydroxide, the salt of an inorganic oxygen-containing acid, an organic salt, optionally in the form of a hydrate or a mixture thereof. As a precursor of the metal ion, the metal in its elemental form can also be used.

Preferred inorganic salts are haiides and sulphides. A halidc is, for example, chloride, bromide or iodide. Preferably is chloride.

An inorganic oxygen-con tai n i ng acid is, for example, sulphuric acid, sulphurous acid, phosphoric acid, perchloric acid or nitric acid.

An organic salt is preferably an acetate, acetylacetonate. citrate or oxalate. The organic compound capable of coordinating to metal ions is a compound prov iding the organic linking moiety to the framework material .

This organic compound is an at least bidentate organic compound, understanding as such an organic compound having at least two atoms which are capable to form coordination bonds w ith the metal ions constitutive of the framework material. The referred atoms can form coordination bonds to a given metal ion or each atom can form a coordination bond with one of the metal ions constitutiv e of the framework material.

All organic compounds w hich are suitable for this purpose and which fulfil the abov e requirement of being at least bidentate may be used.

Depending on the metal ion, its charge and oxidat ion state, a skilled person would know which organic compound can be used for the purposes of the inv ent ion. in a preferred embodiment, the bidentate organic compound is a heteroaromat ic compound having at least two nitrogen atoms. The heteroaromatic compound can have one or more rings, for example, two, three, four or five rings, with the rings being able to be present separately from one another and/or at least two rings being able to be present in fused form.

As mentioned abov e, the heteroaromatic compound has at least two nitrogen atoms which can be in the same or different ring. Preference is given to the at least two nitrogen atoms being present in the same ring of the heteroaromatic compound.

Preferably, the heteroaromatic compound has one or two fused rings, being particularly preferred 5- or 6-membered rings.

The heteroaromatic compound has a nitrogen atom from which a hydrogen has been eliminated. This forms a negative charge which can at least partial ly compensate the positive charge of the metal ion. Said aromatic compound is unsubstituted or has one or more substituents independently selected from Ci„ 6 alkyl, NH 2 , NH( C, ( , alkyl), N(Ci„ 6 alkyl) 2 , OH, =0, 0-C M , alkyl, halogen, cyano or nitro.

For the purpose of the present invent ion, the term alkyl" refers to a linear or branched alkyl group having from 1 to 6 carbon atoms. Examples are methyl, ethyl, n- propyl, i-propyl, n-buty!, i-butyl, sec-butyl, t-butyi, n-pentyl, n-hexy!. Preferred radicals are methyl or ethyl.

Furthermore, the term "halogen" refers to fluorine, chlorine, bromine or iodine. Preference is given to fluorine or chlorine. Preferred substituents of the heteroaromatic compound are C 1-6 alkyl, NH 2 and OH. Further preference is given to Ci_6 alkyl and NH 2 . Particular preference is given to C 1-6 alkyl.

In a further preferred embodiment, the heteroaromatic compound is selected from the group consisting of:

and combinations thereof, wherein, these preferred heteroaromat ic com ounds can also be unsubstituted or can have one or more siibstituents independently selected from d_6 alkyl, NH 2 , NH(Cu, alkyl ). N(C 1-6 alkyl)?- Oi l, =0, O-C , alkyl. halogen, cyano or nitro. In a more preferred embodiment, the heteroaromatic compound is selected from the group consisting of:

and combinations thereof, wherein, these preferred heteroaromatic compounds can also be unsubstituted or can have one or more substituents independently selected from Ci_6 alkyi, NH 2 , NH(Cu, alkyi), (Ci_6 alkyl) 2 , OH, =0, 0-Ci <, alkyi, halogen, cyano or nitro.

Preferred substituents of the heteroaromatic compound are C 1-6 alkyi, NH 2 and OH. Further preference is given to C 1-6 alkyi and NH 2 . Particular preference is given to C 1-6 alley 1.

In an even more preferred embodiment, the heteroaromatic compound is an imidazole optionally substituted with one or more substituents independently selected from Ci_6 alkyi, NH 2 , NH(C, ( , alkyi), N(Ci_ 6 alkyl) 2 , OH, =0, O-C, /, alkyi, halogen, cyano or nitro. Preferred substituents of the imidazole are C 1-6 alkyi, NH 2 and 01 1. Further preference is given to C 1-6 alkyi and NI K Particular preference is given to C 1-6 alkyi.

The molar ratio of the precursor of the metal ion to organic compound in the aqueous solution of step b) is preferably in the range from 1 :5 to 1 : 1. More preference is given to a range from 1 :4 to 1 : 1.2, more preferably from 1 :3 to 1 : 1.5, even more preferably from

1 :2.5 to 1 : 1.75, in particular 1 :2. In order to obtain a framework material in which the metal ion and the organic compound are coordinate! y bound, the organic compound must be deprotonated to coordinate metal centre. Accordingly, the reaction of the metal precursor and the organic compound in the aqueous solution to form the metal-organic framework material requires the presence of a base. In the process of the invention, the alkylamines of formula (I) comprised in the microemulsion obtained in step a) provide the required base in the form of small micelles for the reaction to take place. Therefore, in step c) the aqueous solution prepared in step b) is mixed with the microemulsion prepared in step a). This mixing step ca be carried out by convent ional methods, for example, by stirring, shaking, circulation or pumped circulation. In a preferred embodiment, the referred mixture is conducted by stirring during at least one hour.

The molar proportion of alkylamines of formula (I) to metal ion after the mixture step is preferably in the range from 2: 1 to 100: 1. More preference is given in the range from 2: 1 to 30: 1 , even more preferably from 5 : 1 to 20 : 1.

In a particular embodiment, the mixture is carried out at a temperature in the range from 0°C to 80°C, more preferably from 2°C to 30°C, even more preferably at about 4°C.

The reaction between the metal precursor and the organic compound takes place at atmospheric pressure. However, slightly superatmospheric or subatmospheric pressures can occur due to the apparatus where the reaction takes place.

The ability of the alkylamines to coordinate the metal centre also ensures the encapsulation of the micelles of alkylamines during the coordination polymer grow process, as they are prone to behave as nucleating centre.

Upon mixture of the microemulsion of alkylamines and the aqueous solution of step b), there is prov ided a suspension containing a precipitate consist ing of a metal-organic framework material having micropores with diameters of less than 2 nm, and comprising repeating units comprising a metal ion and an organic linking moiety, wherein said framework material also contains micelles of alkylamines of formula (I) homogeneously distributed therein. Step c) is preferably followed by isolation of the metal-organic framework formed. This step is effected by conventional techniques, such as solid-liquid separations, centrifugation, extraction, filtration, membrane filtration, cross-flow filtration, flocculat ion using floeculat ion adjuvants ( non-ionic, cation ic and anionic adjuvants), by flotation, spray-drying or spray granulation. The isolation step is preferably carried out by filtration with optional subsequent washing. The metal-organic framework material obtained can be subjected to drying. Spray drying is also possible.

Accordingly, in a particular embodiment, the isolation process is followed by a drying step. Said step is preferably carried out at room temperature. The metal-organic framework material obtained after conducting step c), or after isolat ion and drying, is also an invent iv e aspect of the present invention and const itutes an intermediate material in the process of the inv ent ion. The features of this intermediate material will be discussed herein below .

The synthesis of metal-organic framework material in a mieroemulsion of alkylamines of formula (I) in an aqueous solut ion results in the incorporation of alkylamine micelles which can subsequently be remov ed by heating, more preferably under vacuum, generat ing new pores inside the material.

Therefore, the process of the invent ion further comprises a step wherein the metal- organic framework material obtained following the process described abov e is subjected to a heating process at a temperature ranging from 50 to 250°C during at least 1 hour. This step causes the act iv at ion of the framework material by removing the micel les of alkylamines.

The act iv ation process can be speeded up applying vacuum. Alternativ e activ at ion processes such as solv ent exchange and supercrit ical drying can be also applied. The incorporation of micelles of alkylamines of formula (I) during the synthesis of the metal-organic framework material and its subsequent act ivat ion, prov ides addit ional pores to those presented by the material synthesized in the absence of alkylamines of formula (I), with diameters ranging from 0.5 nm to 4 nm, more preferably from 0.5 to 3 nm, ev en more preferably between 0.5 and 2.5 nm, in particular between 0.5 and 2.0 nm.

Furthermore, the incorporation of micelles of alkylamines of formula (I) during the synthesis, and its subsequent activ at ion, also increases the BET surface area of the metal-organic framework material betw een 1 .5 to 5 times the maximum reported v alue for a material synthesized in the absence of said alkylamines, as wel l as the theoretical surface area based on the crystal structure of the material. In part icular with values higher than 3000 m 2 /g, more particularly a surface area comprised between 3200-5600 m 2 /g.

Accordingly, this step yields an ultraporous metal-organic framework material having a BET surface area higher than 3000 m 2 /g and micropores with diameters of less than 2 nm, with additional pores resulting from the removal of the micelles of alkylamines of formula (I) in step d) of the process of the invent ion, said addit ional pores being homogeneously distributed within the framework material and having a diameter from 0.5 to 4 nm.

As a consequence of that, the total pore volume of the material is also increased, thus improving the properties of these framework materials to be used in many applicat ions.

The synthesis methodology using the microemulsion of alkylamines also allows controlling the added porosity through the micel le concentration of the react ion medi m as well as the dimensions of the new pores incorporated in this case through the length of the corresponding amine. All these compounds show additional mass loss stage or stages, belonging to the release of the corresponding alkylamines of formula (I), below 3 ()()"(' compared to the material synthesized in absence of said alkylamines.

Thus, this method provides a way to surpass the limits imposed by the crystal structure of the coordination polymers obtained in absence of the alkylamines of formula (I). With this method, it is provided a qualitative breakthrough in the strategy of introducing addit ional porosity, allowing it to be of more general application to other porous coordination polymers.

It must be emphasized that these new ultraporous materials are obtained at a low cost in terms of both the raw materials and the production and activation methods. Likewise, the alkylamines used as surfactants are susceptible to recovery and reuse, an aspect which would lead to a further reduction in their production cost.

Therefore, a further aspect of the present invention refers to an ultraporous metal- organic framework material obtainable by the process as described above.

This ultraporous metal-organic framework material has a BET surface area higher than 3000 m 2 /g and micropores with diameters of less than 2 nm, said material comprising repeating units comprising a metal ion and an organic linking moiety, characterized in that said material comprises additional pores resulting from the removal of the micel les of alky!amines in step d) of the process of the invention, said additional pores being homogeneously distributed within the framework material and hav ing a diameter from 0.5 to 4 nm. in a preferred embodiment, the diameter of these homogeneously distributed additional pores ranges from 0.5 to 3 nm, even more preferably from 0.5 to 2.5 nm, in part icular from 0.5 to 2.0 nm.

The calculated specific surface areas according to Brunauer-Emmett-Tcller model (DIN 66131) are above 3000 m 2 /g, in particular above 3500 m 2 /g, more particular above 4000 m 2 /g, even more particular abov e 5000 m 2 /g. in another particular embodiment, as the metal component within the framework material, particularly to be mentioned are metal ions of elements of the following group:

Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr. Nb, Mo, Tc, Ru. Rh, Pd, Ag, Cd, Lu, Hf, Ta, W, Re, Os, Ir, Pt, Au, Hg, Al, Be, more preferably Zn, Fe, Mn, Cu, Ni, Al, Be or Co, even more preferably Zn or Co.

As metal ions of these elements, particularly to be mentioned are: Sc 3+ , Ti 4+ , V 5+ , V 4+ , V 3+ , V 2+ , Cr 3+ , Mn 3+ , Mn 2+ , Fe 3+ , Fe 2+ , Co 3+ , Co 2+ , Ni 3+ , Ni 2+ , Cu 2+ , Cu + , Zn 2+ , Y 3+ , Zr* ' . Nb 3+ , Mo 3+ , Ru 3+ , Ru 2+ , Rh ' . Rh + , Pd 2+ , Pd + , Ag 4 , Cd 2+ , U Ta 3+ , W 3+ , Re 3+ , Re 2+ , Os 3+ , Os 2+ , Ir 2 \ Ir + , Pt ' , Pt , Au + , Hg 2+ , Ai 3+ , Be 2+ .

As for the organic linking moiety, it is particularly preferred a heteroaromatic compound having at least two nitrogen atoms. The heteroaromatic compound can have one or more rings, for example, two, three, four or five rings, with the rings being able to be present separately from one another and/or at least two rings being able to be present in fused form.

As mentioned above, the heteroaromatic compound has at least two nitrogen atoms which can be in the same or different ring. Preference is given to the at least two nitrogen atoms being present in the same ring of the heteroaromatic compound.

Preferably, the heteroaromat ic compound has one or two fused rings, being particularly preferred 5- or 6-membered rings. The heteroaromatic compound has a nitrogen atom from which a hydrogen has been eliminated. This forms a negat ive charge which can at least partially compensate the positive charge of the metal ion.

Said heteroaromatic compound is unsubstituted or has one or more substituents independently selected from Ci_ 6 alkyl, NH 2 , NH(C, 6 alkyl), N(Ci_ 6 alkyl) 2 , OH, =0, O- Ci-6 alkyl, halogen, cyano or nitro.

For the purpose of the present invention, the term "Ci_6 alkyl" refers to a linear or branched alkyl group having from 1 to 6 carbon atoms. Examples are methyl, ethyl, n- propyl, i-propyl, n-butyl, i- butyl, sec-butyl, t-butyl, n-pentyl, n-hexyl. Preferred radical are methyl or ethyl.

Furthermore, the term "halogen" refers to fluorine, chlorine, bromine or iodine.

Preference is given to fluorine or chlorine.

Preferred substituents of the heteroaromatic compound are C 1-6 alkyl, Nlf and OH. Further preference is given to Ci_e alkyl and NH 2 . Particular preference is given to d-6 alkyl.

In a further preferred embodiment, the heteroaromatic compound is selected from the group consisting of:

and combinations thereof, wherein, these preferred heteroaromat ic com ounds can also be unsubstituted or can have one o more subst ituents independent ly selected from C 1-6 alkyl, H 2 , NH(Cu, alkyl), N(Ci_6 alkyl ) 2 , OH, O-C, 6 alkyl, halogen, cyano or nitro. In a more preferred embodiment, the heteroaromatic compound is selected from the group consisting of:

and combinations thereof, wherein, these preferred heteroaromatic compounds can also be unsubstituted or can have one or more substituents independently selected from aikyl, NH >, NH(Ci (> alkyl ), alkyl) 2 , OH, O-Cu, alky I, halogen, cyano or nitro.

Preferred substituents of the heteroaromatic compound are C 1-6 alkyl, NH 2 and OH. Further preference is given to C 1-6 alkyl and NH 2 . Particular preference is given to d_6 alkyl.

In an even more preferred embodiment, the heteroaromatic compound is an imidazole optionally substituted with one or more substituents independently selected from d_6 alkyl, NH 2 , NH( C, alkyl), N(d„ 6 alkyl) 2 , OH, O-d aikyl, halogen, cyano or nitro. Preferred substituents of the imidazole are d-6 alkyl, NH 2 and OH. Further preference is given to d-6 alkyl and NH 2 . Particular preference is given to d-6 alkyl.

In another preferred embodiment, the metal-organic framework material comprises repeating units comprising a zinc or cobalt ion and 2-methyl imidazole.

The micropore size of the ultraporous metal-organic framework can be control led by selection of the suitable organic iigand. In general, the larger the organic compound, the larger the pore size. The micropore size is less than 2 nm, preferably from 0. 1 to less than 2 nm, based on the crystalline material.

A.s mentioned above, a further aspect of the present invention refers to an intermediate material obtainable after conducting step c) of the process of the invention and which is a metal-organic framework material. This material has micropores with diameters of less than 2 nm, and comprises repeating units comprising a metal ion and an organic linking moiety, characterized in that said material further comprises micelles of alkylamines homogeneously distributed within the framework material, wherein said alkylamines have the general formula (I):

(I) wherein:

R 1 is a substituted or unsubstituted, linear or branched, alkyl radical having from 4 to

12 carbon atoms; and R 2 and R 3 are each independently a hydrogen atom or a l inear or branched alkyl radical having from 1 to 12 carbon atoms.

By the term "micelle of alkylamines" should be understood an aggregate of alkylamines dispersed in aqueous solution, wherein the hydrophiiic part of the alkyl amine (amine group) is in contact with the surrounding water, sequestering the hydrophobic tail regions (alkyl groups) in the centre of the aggregate.

These micelles are homogeneously distributed within the framework material.

In a preferred embodiment, R 1 is an unsubstituted linear alkyl radical hav ing from 4 to 8 carbon atoms, such as, butyl, pentyl, hexyl, heptyl or octyl.

In another preferred embodiment, at least one of R and R 3 is hydrogen, even more preferably both R and R 3 are hydrogen.

In a preferred embodiment, the alkylamine of formula (I) is a monoaikylamine of formula NH 2 R 1 , wherein R 1 is an unsubstituted linear alkyl radical having from 4 to 8 carbon atoms.

In another preferred embodiment, the metal ions and organic linking moieties are those as mentioned previously for the ultraporous metal-organic framework of the present invention. The ultraporous metal-organic framework material of the present invention may be compounded, extruded, co-extruded, pressed, spinned, foamed and granulated according to processes known by a skilled person.

Depending on the application, the ultraporous metal-organic framework material of the present invention can be used in powder form or shape into extrudates, pellets, granules, rings, films, etc., or can be applied to supports, for instance as coatings on distillation packing or honeycombs and knitted meshes made of metal or polymers. Furthermore, the above methods allow preparing various further and different geometries and shapes, which are necessary for the widespread application areas of said materials. The reactions can, depending on the application, be carried out in a liquid, gaseous or supercritical phase.

As a result of the high surface area of the ultraporous metal-organic framework material of the invention and its porosity, it can be used as adsorbent, desiccant, flame retardant, storage materials and depot materials for sustained release of active ingredients. Furthermore, these materials can, owing to their high porosity and surface area, be used as sensors or in sensors for. for example, gas detection or in applicat ion areas such as "chemistry on a chip"

The ultraporous metal-organic framework material can also be employed in or as electronic component or functional material . In a preferred embodiment, the ultraporous metal-organic framework material of the invention is used as gas storage material and/or gas release material. As the gases to be storage and/or released, particularly mentioned are hydrocarbons, alcohols, hydrogen, nitrogen, noble gases, CO, ( ' ().% natural gases, synthesis gas, compounds generating and/or delivering these gases and mixtures of two or more thereof. Particularly preferred are hydrogen, a hydrogen containing gas mixture, a hydrogen generating or delivering substance, a gas mixture comprising at least one hydrogen generat ing and/or delivering substance.

EXAMPLES Example 1. Preparation of Co (2-methylim.idazolate)?(n-pentylam.ine)o.48(H70)o.33 A mixture of 20 mL of water and 5.9 mL (50 mmol) of n-pentylamine was stirred for several minutes. The solution was mixed under vigorous stirring with an aqueous solution (30 mL) containing 1.188 g (4.0 mmoi) of Co(N0 3 ) 2 and 0.663 g (8.0 mmoi) of 2-methylimidazoie. The reaction mixture was left stirring for one hour at 4°C. Thereafter, the precipitate was filtered out, thoroughly washed with water and allowed to dry at room temperature. Prior to gas adsorption measurements the material was activated at 150 °C during 12 h under an applied vacuum of 10 5 atm. In order to analyze the permanent porosity of the material N 2 adsorption isotherms were collected at 77 K. The surface area of the material was 3582 m 2 /g according to the BET analysis o the N 2 isotherm. T- iot analysis yielded micropore surface area of 3425 m 2 /g, mesopore (external) surface area of 157 m 2 /g and micropore volume of 1.375 cm 3 /g. The total pore volume of the material estimated at P/Po ca. 0.96 is 1.535 cm 3 /g. According to the state of the art, the maximum BET surface area obtained for cobait(II) 2- methylimidazo lates synthesised in absence of alkylamines of general formula (I) is 2070 m 2 /g, see article: M. Lanchas et al., Chem. Commun. 2012, 48, 9930.

Example 2. Preparation of Co (2-methylimidazolate)7(n-hexylamine)o.44(H Q)5.2i

A mixture of 10 ml. o water and 2.7 ml. (20 mmol ) of n-hexylamine was stirred for several minutes. The solution was mixed under vigorous stirring with an aqueous solution (30 ml. ) containing 1.188 g (4.0 mmol ) of Co(N0 3 ) 2 and 0.663 g (8.0 mmol ) of 2-methylimidazoie. The reaction mixture was left stirring for one hour at 4°C. Thereafter, the precipitate was filtered out, thoroughly washed with water and allowed to dry at room temperature. Prior to gas adsorption measurements the material was activated at 1 50 °C during 12 h under an applied vacuum of 10° atm. In order to analyze the permanent porosity of the material N 2 adsorption isotherms were collected at 77 K. The surface area of the material was 3222 m 2 /g according to the BET analysis o the N 2 isotherm. T- lot analysis yielded micropore surface area o 3005 m 2 /g, mesopore (external) surface area of 216 m 2 /g and micropore volume o 1 .2 1 5 cm 3 /g. The total pore volume of the material estimated at P P 0 ca. 0.96 is 1.370 cmVg. According to the state of the art, the maximum BET surface area obtained for cobait(II) 2- me thy limidazo lates synthesised in absence of alkylamines of general formula (I) is 2070 m 2 /g, see article: M. Lanchas et al, Chem. Commun. 2012, 48, 9930. Example 3. Preparation of Co i (2-mcthylimidazolatc) (n-hcxylaminc)o.55( lI ·0)ο.

A mixture of 10 ml. of water and 5.4 ml, (40 mmol) of n-hexylamine was stirred for several minutes. The solution was mixed under vigorous stirring with an aqueous solutio (30 ml . ) containing 1.188 g (4.0 mmol) of Co(N0 3 ) 2 and 0.663 g (8.0 mmoi) of 2 - met h y ! i mid azo 1 e . The reaction mixture was left stirring for one hour at 4°C. Thereafter, the precipitate was filtered out. thoroughly washed ith water and allowed to dry at room temperature. Prior to gas adsorption measurements the material was activated at 150 °C during 12 h under an applied vacuum of 1 0 atm. In order to analyze the permanent porosity of the material N 2 adsorption isotherms were collected at 77 K. The surface area of the material was 4650 m 2 /g according to the BET analysis of the N 2 isotherm. T-plot analysis yielded micropore surface area of 4305 m 2 /g, mesoporc (external) surface area of 344 m 2 /g and micropore volume of 1.731 cm 3 /g. The total pore volume of the material est imated at P/Po ca. 0.96 is 2. 132 cffiVg. According to the state of the art, the maximum BET surface area obtained for cobalt(II) 2- methyiimidazoiates synthesised in absence of alkylamines of general formula (I) is 2070 m 2 /g, see article: M. Lanchas et al., ( " hem. Commun. 2012, 48, 9930.

Example 4. Preparation of Co (2-methylimidazolate)2:(n-heptylam.ine)o.55(H70)o.35

A mixture of 20 ml. of water and 3.0 ml. ( 20 mmol ) of n-heptylamine was st irred for several minutes. The solution was mixed under vigorous stirring with an aqueous solution (30 ml . ) containing 1 . 1 8 g (4.0 mmol ) of Co(N0 3 ) 2 and 0.663 g (8.0 mmol) of 2-mcthyl imidazole. The react ion mixture was left stirring for one hour at 4°C. Thereafter, the precipitate was filtered out, thoroughly washed ith water and allowed to dry at room, temperature. Prior to gas adsorption measurements the material was activated at 1 50 °C during 12 h under an applied vacuum of 1 0 atm. In order to analyze the permanent porosity of the material N 2 adsorption isotherms were collected at 77 K. The surface area of the material was 55 1 m 2 /g according to the BET analysis of the N 2 isotherm. T-plot analysis yielded micropore surface area of 51 16 m 2 /g, m.esopore (external) surface area of 474 m 2 /g and micropore volume of 2.060 cmVg. The total pore volume of the material estimated at P/Po ca. 0.96 is 2.690 cmVg. According to the state of the art, the maxim m BET surface area obtained for cobait(II) 2- m et hy limid azo I at cs synthesised in absence of alky lam ines of general formula (I) is 2070 m 2 /g, see article: M. Lanchas et al, Chem. Commun. 2012, 48, 9930.