METHOD FOR PRODUCING METAL-ORGANIC FRAMEWORKS

Abstract

The present invention relates to a method for the preparation of a metal-organic framework structure compound, the metal-organic framework structure compound being prepared such as well as the use of the metal-organic framework structure compound being prepared such as adsorbent.

Claims

1. A method for the preparation of a metal-organic framework structure compound comprising the steps of: reacting at least one metal salt comprising a metal cation which is selected from the group consisting of the transition metals and Al as well as combinations thereof, with a linker compound, wherein the reaction is conducted at a pressure of less than 1.5 bar in aqueous solution, and wherein the linker compound is an isophthalate or a derivate thereof.

2. The method according to claim 1, wherein the aqueous solution comprises less than 10% by volume of organic solvents.

3. The method according to claim 1, wherein the reaction is conducted at a temperature of 80 to 120 C. or higher.

4. The method according to claim 1, wherein the reaction is conducted over a period of time of 10 hours or less.

5. The method according to claim 1, wherein the linker compounds are structures of the general formula 2: ##STR00002## wherein the groups R1 to R4 are independently from each other selected from hydrogen, hydroxyl, nitro, amino, methyl, ether and halogenide groups as well as combinations thereof.

6. (canceled)

7. The method according to claim 1, wherein the metal salt is selected from the group consisting of iron and aluminum salts.

8. (canceled)

9. The method according to claim 1, wherein to the aqueous solution a base is added.

10-14. (canceled)

15. The method according to claim 1, wherein the reaction is conducted at the boiling point of the reaction medium.

Description

EXAMPLES

[0056] For the samples to be investigated at the beginning of the ageing process being independent on cycles a starting measurement with nitrogen (N.sub.2) at 77 kelvins was conducted on a NOVA 3000e of the company Quantachrome. Via the nitrogen measurement at 77 kelvins information about the change of the pore structure (distribution of the pore radii), pore volumes as well as about the internal surface area (BET) can be gathered. For removing humidity and foreign gases from the samples, before the actual measurement, they were baked out in high vacuum for 24 h at 120 C. Subsequently, the dry weight of the sample was measured by means of an analytical balance of the company Sartorius with the class of accuracy I. Subsequently, complete isotherms in adsorption and desorption were measured and evaluated. The relative pressure range was between p/p0=0.05-0.999 in the case of adsorption and p/p0=0.999-0.1 in the case of desorption. The pore volume was calculated according to the density functional theory (DFT) and according to the model of Dubinin and Astakhov (DA). The internal surface area was calculated according to the model of BrunauerEmmett-Teller (BET) between p/p0=0.05 and 0.15.

Comparative Example

[0057] Synthesis:

[0058] 200 mg of 1,3-isophthalic acid (1,3-H.sub.2BDC, 1.20 mmol), dissolved in 1 mL of N,N-dimethyl formamide (DMF), were mixed with 800 mg of Al.sub.2(SO.sub.4).sub.3*18H.sub.2O, dissolved in 4 mL of H.sub.2O, and treated in a Teflon-lined steel autoclave for 12 hours at 135 C.

[0059] Working-Up:

[0060] After allowing to cool down to room temperature the product was filtrated and washed with water in an ultrasonic bath. The white solid obtained was dried and subsequently activated at 120 C. in vacuum for 24 hours.

[0061] The specific surface area of the product was S.sub.BET=525 m.sup.2/g and the pore volume was 0.27 cm.sup.3/g.

Embodiment Example 1

[0062] Synthesis:

[0063] A solution of 0.75 mol (125 g) of isophthalic acid in 600 ml of DMF and 2400 ml of water and 0.72 mmol (483 g) of Al.sub.2(SO.sub.4).sub.3*18H.sub.2O were heated in a 5000 ml three-necked flask to 135 C.

[0064] In a 5 L flask 483 g (0.72 mol) of Al.sub.2(SO.sub.4).sub.3*18H.sub.2O were completely dissolved in 2.4 L of water. To the aluminum sulfate solution 125 g (0.75 mol) of isophthalic acid, dissolved in 600 mL of DMF, were added in portions.

[0065] The solution was refluxed under stirring for a period of time of 48 h.

[0066] Working-Up:

[0067] The solid formed was filtered off with the help of a fluted filter (5-13 m), resuspended in H.sub.2O and placed in an ultrasonic bath for 30 minutes. This procedure was repeated three times. Subsequently, the white solid was dried for 5 days at 90 C. in the drying oven and for 1 day at 120 C. in the vacuum oven.

[0068] After the purification 156.8 g of a white solid with S.sub.BET=578 m.sup.2/g were obtained. The single crystalline phase was identified by means of X-ray powder diffraction analysis as CAU-10-H. FIG. 6 shows the powder diffractogram of CAU-10-H.

Embodiment Example 2

[0069] Synthesis:

[0070] 5 L of a 0.5 M sodium isophthalate solution were prepared by making up sodium hydroxide (199.99 g; 5 mol) and isophthalic acid (415.33 g; 2.5 mol) in a graduated volumetric flask with H.sub.2O to a volume of 5000 ml. Furthermore, 2 L of a 0.5 M aluminum sulfate*18H.sub.2O solution (666.15 g; 1 mol) and 2 L of a 0.5 M sodium aluminate solution (81.79 g; 1 mol), each by making up in a graduated volumetric flask with H.sub.2O to a volume of 2000 mL, were prepared each. For the reaction 2.16 L of sodium isophthalate solution (0.5 M) and 180 mL of ethanol were combined and under stirring 810 mL of aluminum sulfate solution (0.5 M) and 540 mL of sodium aluminate solution (0.5 M) were added. Subsequently, the reaction was conducted for 6 h under reflux and stirring.

[0071] Working-Up:

[0072] The solid obtained was filtered off, washed with a plenty of water and ethanol and dried over night at 90 C. 207 g (92% yield) of a white powdery solid (S.sub.BET=580 m.sup.2/g) were obtained, and this was identified as CAU-10-H by means of X-ray powder diffraction analysis. The N.sub.2 sorption isotherm is shown in FIG. 1; filled squares describe the adsorption curve and empty squares describe the desorption curve.

Embodiment Example 3

[0073] Synthesis:

[0074] For the synthesis 100 mL of a 0.5 M sodium isophthalate solution were prepared by making up sodium hydroxide (3.99 g, 0.1 mol) and isophthalic acid (8.30 g; 0.05 mol) in a graduated volumetric flask with H.sub.2O to a volume of 100 ml. Furthermore, 100 mL of a 0.5 M aluminum sulfate*18H.sub.2O solution (33.308 g; 0.05 mol) and 100 mL of a 2 M sodium hydroxide solution (7.99 g; 0.2 mol), each by making up in a graduated volumetric flask with H.sub.2O to a volume of 100 mL, were prepared each. For the reaction 127.5 mL of H.sub.2O, 7.5 mL of ethanol and 90 mL of sodium isophthalate solution were combined and under stirring 45 mL of aluminum sulfate solution and 22.5 mL of sodium hydroxide solution were added. Subsequently, the reaction was conducted for 6 h under reflux and stirring.

[0075] Working-Up: The solid obtained was filtered off, washed with a plenty of water and ethanol and dried over night at 100 C. A powdery solid (S.sub.BET=573 m.sup.2/g) was obtained which was identified by means of X-ray powder diffraction analysis as CAU-10-H. Furthermore, the reaction product contained a minor phase (sodium alunite, NaAl.sub.3(OH).sub.6(SO.sub.4).sub.2; #(ICSD)=44626). The N.sub.2 sorption isotherm is shown in FIG. 2; filled squares describe the adsorption curve and empty squares describe the desorption curve.

Embodiment Example 4

[0076] Synthesis:

[0077] 5.25 mL of a 0.5 M sodium isophthalate solution was stirred up with 4.5 mL of water. Under stirring 5.25 mL of a 0.5 M FeCl.sub.3 solution were added. Subsequently, the reaction was conducted for 6 h at 95 C. in the microwave under stirring.

[0078] Working-Up:

[0079] The solid obtained was filtered off, washed with a plenty of water and ethanol and dried over night at 90 C. It was possible to identify it as Fe-MIL-59. FIG. 3 shows the water sorption isotherm obtained with this substance.

Embodiment Example 5

[0080] For a further synthesis of Fe-MIL-59 100 mL of m-Na.sub.2-BDC solution (0.5 M) and 50 mL of water were combined and under stirring 100 mL of FeCl.sub.3 solution (0.5 M) were added. The reaction was conducted under vigorous stirring and reflux for 6 hours. The solid obtained was filtered off by means of a very fine filter and the solid was washed thoroughly with water. The product was dried in the drying oven (90 C.) for 3 days. An orange-brown solid was obtained. The yield was 12.55 g (max. 12.8 g, 98%). The powder diffractogram measured is shown in FIG. 4. As a comparison the diffractogram of vanadium MIL-59 which is isostructural is shown.

Embodiment Example 6

[0081] 7.5 mL of Na.sub.2TDC solution (0.5 M) were provided, and under stirring 5.625 mL of AlCl.sub.3 solution (0.5 M) and 1.875 mL of NaAlO.sub.2 solution (0.5 M) were added. The reaction was conducted for 3 h at 95 C. under stirring in the microwave. The solid obtained was filtrated and washed with water and ethanol. An analysis resulted in a surface area (BET) of 1024 m.sup.2/g and a pore volume=0.4381 cm.sup.3/g. FIG. 5 shows the N.sub.2 sorption isotherm.

[0082] A synopsis of the comparative example and the embodiment example 1 results in the finding that the synthesis method according to the present invention in comparison to common methods which are conducted in the presence of an increased pressure results in metal-organic framework structure compounds with larger specific surface area.

[0083] From the comparison of embodiment example 1 and the embodiment examples 2 and 3 it is obvious that the use of isophthalates in aqueous reaction media substantially reduces the reaction time.

[0084] Embodiment example 4 shows that the reaction does not only work with aluminum as the metal component.

[0085] Embodiment example 6 shows that the reaction can analogously be conducted with other aromatic dicarboxylic acids.