PROCESS FOR PREPARING METAL ORGANIC FRAMEWORKS HAVING IMPROVED WATER STABILITY

Abstract

This invention relates to a continuous process for the preparation of a metal-organic framework comprising a hydrophobic compound. The process comprises the steps of: (a) providing a first component comprising either (i) a metal-organic framework, or (ii) a first reactant which includes at least one metal in ionic form and a second reactant which includes at least one ligand capable of associating with the metal in ionic form in order to form a metal-organic framework, (b) providing a hydrophobic compound, and (c) mixing the first component and the hydrophobic compound in order to form the metal-organic framework comprising the hydrophobic compound. The invention also relates to the use of a hydrophobic polymer, a silane compound and/or a siloxane compound to improve the water stability of a metal-organic framework.

Claims

1. A continuous process for the preparation of a metal-organic framework comprising a hydrophobic compound, the process comprising the steps of: (a) providing a first component comprising either (i) a metal-organic framework, or (ii) a first reactant which includes at least one metal in ionic form and a second reactant which includes at least one ligand capable of associating with the metal in ionic form in order to form a metal-organic framework, (b) providing a hydrophobic compound, and (c) mixing the first component and the hydrophobic compound in order to form the metal-organic framework comprising the hydrophobic compound.

2. A process as claimed in claim 1, wherein the metal-organic framework is selected from HKUST-1, ZIF-8, Al(fumarate)(OH), SIFSIX-3-Zn, SIFSIX-3-Cu, UiO-66-NH.sub.2, UiO-66, Zr(fumarate), ZIF-67, MOF-5, IRMOF-3, UiO-67, CAU-10, SIFSIX-3-Ni, MIL-53, MIL-101, NOTT-100, PCN-14, SIFSIX-3-Co, ZIF-90, ZIF-7, BIT-101, Mg-formate, TIFSIX-3-Ni, MIL-100, MOF-74, MOF-177, CuBTTri, IRMOF-3, MOF-5CH.sub.3, PCN-222, and UiO-66-CH.sub.3.

3. A process as claimed in claim 2, wherein the metal-organic framework is HKUST-1 or Cu-MOF-74.

4. A process as claimed in claim 3, wherein the first reactant is a nitrate, nitrite, sulfate, hydrogen sulphate, oxide, halide, acetate, oxide, hydroxide, benzoate, alkoxide, carbonate, acetylacetonate, hydrogen carbonate, fluoride, chloride, bromide, iodide, phosphate, hydrogen phosphate or dihydrogen phosphate salt.

5. A process as claimed in claim 4, wherein the first reactant is copper (II) hydroxide.

6. A process as claimed in claim 5, wherein the at least one metal in ionic form is selected from Li.sup.+, Na.sup.+, K.sup.+, Mg.sup.2+, Ca.sup.2+, Sr.sup.+, Ba.sup.2+, Sc.sup.3+, Y.sup.3+, Ti.sup.4+, Zr.sup.4+, Hf.sup.4+, Y.sup.4+, Y.sup.3+, Y.sup.2+, Nb.sup.3+, Ta.sup.3+, Cr.sup.3+, Cr.sup.4+, Cr.sup.6+, Mo.sup.3+, Mo.sup.6+, W.sup.3+, Mn.sup.3+, Mn.sup.2+, Re.sup.3+, Re.sup.2+, Fe.sup.3+, Fe.sup.2+, Ru.sup.3+, Ru.sup.2+, Os.sup.3+, Os.sup.2+, Co.sup.3+, Co.sup.2+, Rh.sup.2+, Rh.sup.+, Ir.sup.+, Ni.sup.+, Pd.sup.2+, Pd.sup.+, Pd.sup.4+, Pt.sup.2+, Pt.sup.+, Pt.sup.4+, Cu.sup.2+, Cu.sup.+, Ag.sup.+, Au.sup.+, Au.sup.3+, Zn.sup.2+, Cd.sup.2+, Hg.sup.2+, Al.sup.3+, Ga.sup.3+, In.sup.3+, Ti.sup.3+, Si.sup.4+, Si.sup.2+, Ge.sup.4+, Ge.sup.2+, Sn.sup.4+, Sn.sup.2+, Pb.sup.4+, Pb.sup.2+, As.sup.5+, As.sup.3+, As.sup.+, Sb.sup.5+, Sb.sup.3+, Sb.sup.+, Bi.sup.5+, Bi.sup.3+ and Bi.sup.+, a lanthanide ions including La.sup.3+, Ce.sup.3+, Ce.sup.4+, Pr.sup.3+, Nd.sup.3+, Pm.sup.3+, Sm.sup.3+, Eu.sup.3+, Gd.sup.3+, Tb.sup.3+, Dy.sup.3+, Ho.sup.3+, Er.sup.3+, Tm.sup.3+, Yb.sup.3+, Lu.sup.3+, and actinide ions including Th.sup.3+, Pa.sup.3+, U.sup.3+, U.sup.6+, Np.sup.3+, Pu.sup.3+, Am.sup.3+, Cm.sup.3+, Bk.sup.3+, Cf.sup.3+, Es.sup.3+, Fm.sup.3+, Md.sup.3+, No.sup.3+ and Lr.sup.3+.

7. A process as claimed in claim 6, wherein the at least one metal in ionic form is Cu.sup.2+.

8. A process as claimed in claim 7, wherein the at least one ligand capable of associating with the metal in ionic form is either an organic ligand selected from carboxylates, imidazoles, sulfonates, phosponates, peptides, carboranes, polyoxymetalates, heterocycles, and derivatives thereof; and mixtures thereof; or an inorganic ligand selected from SiF.sub.6, TiF.sub.6 and oxalate and mixtures thereof.

9. A process as claimed in claim 8, wherein the at least one ligand capable of associating with the metal in ionic form is a trimesate.

10. A process as claimed in claim 9, wherein the hydrophobic compound is a hydrophobic polymer, a silane compound and/or a siloxane compound.

11. A process as claimed in claim 10, wherein the hydrophobic polymer is an acrylic, amide, imide, carbonate, diene, ester, ether, fluorocarbon, olefin, styrene, vinyl acetal, vinyl acetate, vinyl, vinylidene chloride, vinyl ester, vinyl ether, vinyl ketone, vinylpyridine, or vinylpyrrolidone polymer.

12. A process as claimed in claim 10, wherein the siloxane compound is selected from octamethyltrisiloxane, polydimethyl siloxane, methylmethoxy siloxane, phenylmethoxy siloxane, methyl silsesquioxane and phenyl silsesquioxane, and mixtures thereof.

13. A process as claimed in claim 12, wherein the silane or siloxane compound is selected from octamethyltrisiloxane, trimethoxy(methyl)silane, polydimethyl siloxane and mixtures thereof.

14. A process as claimed in claim 13, wherein step (b) comprises providing a solution comprising a silane compound and a siloxane compound.

15. A process as claimed in claim 14, wherein step (b) comprises providing a solution comprising octamethyltrisiloxane, polydimethyl siloxane, methylmethoxy siloxane, phenylmethoxy siloxane, methyl silsesquioxane, phenyl silsesquioxane and trimethoxy(methyl)silane.

16. A process as claimed in claim 15, wherein step (b) comprises providing a solution comprising the hydrophobic compound and step (c) comprises mixing the first component and the solution in order to form the metal-organic framework comprising the hydrophobic compound.

17. A process as claimed in claim 16, wherein the solution comprises a solvent selected from methanol, ethanol, acetone, isopropanol, hexane, heptane, water and mixtures thereof.

18. A process as claimed in claim 17, wherein in step (c) the mixing is under conditions of prolonged and sustained pressure and shear.

19. A process as claimed in claim 18, wherein the conditions of prolonged and sustained pressure and shear are applied by an extrusion process.

20. A process as claimed in claim 19, wherein in step (c) the mixing is carried out at a temperature of less than 150° C.

21. A process as claimed in claim 20 additionally comprising, after step (c), the step of: (d) drying the metal-organic framework.

22. A process as claimed in claim 21 additionally comprising, after step (c) or step (d), the step of: (e) forming a shaped body comprising the metal-organic framework.

23. The use of a hydrophobic polymer, a silane compound and/or a siloxane compound to improve the water stability of a metal-organic framework.

Description

[0064] This invention will be further described by reference to the following Figures which are not intended to limit the scope of the invention claimed, in which:

[0065] FIG. 1 shows a bar chart comparing the hydrothermal stability of CuBTC and the material of Example 1,

[0066] FIG. 2 shows N.sub.2 isotherms at 77K for CuBTC and the material of Example 1 exposed to humid conditions,

[0067] FIG. 3 shows XRD data for CuBTC exposed to humid conditions,

[0068] FIG. 4 shows XRD data for the material of Example 1 exposed to humid conditions,

[0069] FIG. 5 shows the colour change demonstrated by CuBTC and the material of Example 1 exposed to humid conditions,

[0070] FIG. 6 shows SEM images of CuBTC and the material of Example 1 exposed to humid conditions,

[0071] FIG. 7 shows XRD data for Cu-MOF-74 exposed to humid conditions,

[0072] FIG. 8 shows a bar chart comparing the hydrothermal stability of Cu-MOF-74 and the material of Example 6,

[0073] FIG. 9 shows N.sub.2 isotherms at 77K for Cu-MOF-74 and the material of Example 6,

[0074] FIG. 10 shows XRD data for the material of Example 6 exposed to humid conditions,

[0075] FIG. 11 shows SEM images the material of Example 6 exposed to humid conditions, which demonstrates that there is no significant degradation,

[0076] FIG. 12 shows a bar chart comparing the hydrothermal stability of Cu-MOF-74 and the material of Example 8,

[0077] FIG. 13 shows N.sub.2 isotherms at 77K for Cu-MOF-74 and the material of Example 8,

[0078] FIG. 14 shows XRD data for the material of Example 8 exposed to humid conditions,

[0079] FIG. 15 shows a bar chart comparing the hydrothermal stability of CuBTC and the material of Example 14,

[0080] FIG. 16 shows N.sub.2 isotherms at 77K for CuBTC and the material of Example 14, and

[0081] FIG. 17 shows XRD data for the material of Example 14 exposed to humid conditions.

EXAMPLES

Example 1: Processing CuBTC (Powder) with Siloxanes/Silanes

[0082] A copper-trimesate MOF was processed in a twin screw extruder (Thermofisher Process 11), as follows.

[0083] Commercially available CuBTC was fed into the extruder using a volumetric feeder at a rate of 0.6 g/min. A solution containing a mixture of siloxanes/silanes (2.5 g of DC 1-2577) in 100 ml acetone was fed into the extruder at 1.9 mL/min. The mixture was processed through the barrel at 55 rpm. The temperature of the barrel was 25° C. The extrudate was collected and dried overnight under vacuum at room temperature. The BET surface area of the product was determined to be 1484 m.sup.2/g.

Example 2: Hydrothermal Stability Studies of CuBTC (Powder) with Siloxanes/Silanes

[0084] Commercially available CuBTC was exposed to 100% relative humidity at 50° C. for 14 days. The BET surface area of this material decreased from 1621 m.sup.2/g to 549 m.sup.2/g after 2 days, ie a drop of approximately 66%, and to 82 m.sup.2/g after 14 days, ie a total drop of approximately 95%.

[0085] Material prepared according to Example 1 above, ie siloxane/silane treated CuBTC, was also exposed to 100% relative humidity at 50° C. for 14 days. The BET surface area of this material also decreased. However, the decrease for this material was much less, from 1484 m.sup.2/g to 1445 m.sup.2/g after 2 days, ie a drop of approximately 3%, and to 1054 m.sup.2/g after 14 days. This is a total drop of only around 29%.

[0086] These results are shown in Table 1 below, and as a bar chart in FIG. 1.

TABLE-US-00003 TABLE 1 Material exposed to 100% RH at 50° C. 0 h 2 days 14 days CuBTC* 1621 m.sup.2/g  549 m.sup.2/g  82 m.sup.2/g siloxanes/silane treated 1484 m.sup.2/g 1445 m.sup.2/g 1054 m.sup.2/g CuBTC (MTA 16) *comparative example

[0087] N.sub.2 adsorption/desorption isotherms were also measured for CuBTC and siloxane/silane treated CuBTC both before humidity exposure and after exposure to 100% relative humidity at 50° C. for 14 days. The equipment used was a Belsorp Mini II, the N.sub.2 adsorption isotherms being recorded at 77 K. The results are shown in FIG. 2 (CuBTC=squares, siloxane/silane treated CuBTC=triangles; filled=before, empty=after). Whilst both materials exhibit a decline in N.sub.2 adsorption, the reduction is much more significant for CuBTC than it is for siloxanes/silane treated CuBTC.

[0088] Powder X-ray diffraction data was also collected for CuBTC and siloxanes/silane treated CuBTC. The equipment used was a Panalytical Aeris. Measurements were made before humidity exposure, as well as after 2, 4 and 14 days of exposure to 100% relative humidity at 50° C. This data is shown in FIGS. 3 (CuBTC) and 4 (siloxane/silane treated CuBTC).

[0089] The deterioration of the CuBTC sample is clearly shown by the change in the XRD trace from the before exposure sample (bottom trace) up through the increasing exposure times (2, 4, and then the top trace for 14 days). In contrast, siloxane/silane treated CuBTC sample shows very little difference between the before exposure sample (bottom trace) and that after 14 days exposure to humidity (top trace).

[0090] Further evidence of the deterioration of the CuBTC sample is shown by its change in colour from before its exposure to humidity, through to exposure to 100% relative humidity at 50° C. after 2, 4 and 14 days. This is shown in FIG. 5, in which the top sample is CuBTC and the bottom sample is siloxane/silane treated CuBTC. The colour of the CuBTC sample clearly fades as the duration of humidity exposure increases, whereas the colour of the siloxane/silane treated CuBTC sample remains substantially the same.

[0091] FIG. 6 shows SEM images of CuBTC (top row) and siloxane/silane treated CuBTC (bottom row) before humidity exposure and after 2 and 14 days of exposure to 100% relative humidity at 50° C. These images demonstrate a substantial change in the morphology of CuBTC particles upon exposure to humidity, which is in agreement with the structure deterioration determined by XRD and BET analysis. In contrast, the siloxane/silane treated CuBTC particles showed very little change after exposure to humidity for 14 days.

Example 3: Preparing and Processing CuBTC (Powder) with Siloxane/Silanes

[0092] In the third example, a copper-trimesate MOF was synthesised and processed in the extruder (Thermofisher Process 11), as follows.

[0093] A mixture of copper (II) hydroxide and trimesic acid (in stoichiometric ratio) was fed into the extruder using a volumetric feeder at a rate of 0.6 g/min. A solution containing a mixture of siloxanes/silanes (2.5 g of DC 1-2577) in 100 ml of acetone/methanol (50:50) was fed into the extruder at 1.9 mL/min. The mixture was processed through the barrel at 55 rpm. The temperature of the barrel was 25° C. The extrudate was collected and dried overnight under vacuum at room temperature. The BET surface area of the product was determined to be 1255 m.sup.2/g.

Example 4: Processed CuBTC in Shaped Form (Extrudates) with Siloxanes/Silanes

[0094] In the fourth example, a copper-trimesate MOF was prepared and processed in the extruder (Thermofisher Process 11) in shaped form, as follows.

[0095] A mixture of copper (II) hydroxide and trimesic acid (in stoichiometric ratio) was fed into the extruder using a volumetric feeder at a rate of 1.6 g/min. A solution containing a mixture of siloxanes/silanes (6.35 g of DC 1-2577) in 100 ml of acetone/methanol (50:50) was fed into the extruder at 1.9 mL/min. The mixture was processed through the barrel at 55 rpm. The temperature of the barrel was 25° C. At the end of the barrel a 2 mm die was connected. The extrudate was collected in pellet form (2 mm diameter) and dried overnight under vacuum at room temperature. The BET surface area of the product was determined to be 1642 m.sup.2/g.

Example 5: Hydrothermal Stability Studies of CuBTC in Shaped Form (Extrudates) with Siloxanes/Silanes

[0096] Commercially available 2 mm CuBTC pellets were exposed to 100% relative humidity at 50° C. for 14 days. The BET surface area of this material decreased from 1559 m.sup.2/g to 53 m.sup.2/g, ie a drop of approximately 97%.

[0097] Material prepared according to Example 4 was also exposed to 100% relative humidity at 50° C. for 14 days. The BET surface area of this material also decreased. However, the decrease for this material was much less, from 1642 m.sup.2/g to 837 m.sup.2/g. This is a drop of only around 51%. A similar result was obtained when drying at 150° C. (as was the case for all of the examples).

Example 6: Processing Cu-MOF-74 (Powder by Extrusion) with Siloxanes/Silanes

[0098] In the sixth example, a commercially available copper-2,5-dihydroxiterephthalate MOF (ie Cu-MOF-74) was processed in a twin screw extruder (Thermofisher Process 11), as follows.

[0099] Cu-MOF-74 was fed into the extruder using a volumetric feeder at a rate of 0.25 g/min. A solution containing 2.43 g of silane/siloxane mixture (ie DC 1-2577) in 100 mL acetone was fed into the extruder at 0.7 mL/min. The mixture was processed through the barrel at 55 rpm. The temperature of the barrel was 30° C. The extrudate was collected and dried overnight under vacuum at room temperature. The BET surface area of the product was determined to be 541 m.sup.2/g.

Example 7: Processing Cu-MOF-74 (Powder by Sonication) with Siloxanes/Silanes

[0100] In the seventh example, a commercially available copper-2,5-dihydroxiterephthalate MOF was processed in an ultrasound bath, as follows.

[0101] 1 g of Cu-MOF-74 was added into a 10 mL acetone solution containing 0.10 g of silane/siloxane (ie DC 1-2577). The mixture was processed at 30° C. for 60 minutes. The solid was recovered from the solution and dried overnight under vacuum at room temperature. The BET surface area of the product was determined to be 794 m.sup.2/g.

Example 8 Preparing and Processing Cu-MOF-74 (Powder by Solution) with Siloxane/Silanes

[0102] In the eighth example, a copper-2,5-dihydroxyterephthalate MOF was processed in solution, as follows.

[0103] 1.03 g of the commercially available copper-trimesate MOF was added to a 10 mL acetone solution containing 0.30 g of silicones/silane (DC-1-2577). The mixture was processed at 70° C. (ie at reflux) for 60 minutes. The solid was recovered from the solution and dried overnight under vacuum at room temperature. The BET surface area of the product was determined to be 972 m.sup.2/g.

Example 9: Hydrothermal Stability Studies of Cu-MOF-74 (Powder by Extrusion, Sonication and Solution) with Siloxanes/Silanes

[0104] Commercially available Cu-MOF-74 was exposed to 100% relative humidity at 70° C. for 2 days. The BET surface area decreased from 1129 m.sup.2/g to 28 m.sup.2/g.

[0105] Material prepared according to Example 6 was also exposed to 100% relative humidity at 70° C. for 2 days. The BET surface area decreased from 541 m.sup.2/g to 526 m.sup.2/g. This data is shown in FIG. 8.

[0106] Material prepared according to Example 7 was also exposed to 100% relative humidity at 70° C. for 2 days. The BET surface area decreased from 794 m.sup.2/g to 758 m.sup.2/g.

[0107] Material prepared according to Example 8 was also exposed to 100% relative humidity at 70° C. for 2 days. The BET surface area of this material also decreased. However, the decrease for this material was much less, from 972 m.sup.2/g to 389 m.sup.2/g.

[0108] Again, this showed that the decrease in BET surface area was much less for the inventive materials of Examples 6, 7 and 8 than it was for Cu-MOF-74.

[0109] N.sub.2 adsorption/desorption isotherms were also measured for Cu-MOF-74 and the material of Examples 6 and 8 both before humidity exposure and after exposure to 100% relative humidity at 70° C. for 2 days. The equipment used was a Belsorp Mini II, the N.sub.2 adsorption isotherms being recorded at 77 K. The results are shown in FIG. 9 (Example 6) and FIG. 13 (Example 8). This shows that Cu-MOF-74 experiences a significant decline in N.sub.2 adsorption, whilst the material of Examples 6 and 8 had only slightly lower adsorption.

[0110] Powder X-ray diffraction data was also collected for Cu-MOF-74, and the materials of Examples 6 and 8. The equipment used was a Panalytical Aeris. Measurements were made before humidity exposure, as well as after 2 days of exposure to 100% relative humidity at 70° C. This data is shown in FIGS. 7 (Cu-MOF-74), 10 (Example 6) and 14 (Example 8).

[0111] The deterioration of the Cu-MOF-74 sample is clearly shown by the change in the XRD trace from the before exposure sample (bottom trace) to the 2 day sample (top trace). In contrast, material of Examples 6 and 8 shows very little difference between the before exposure sample (bottom trace) and that after 2 days' exposure to humidity (top trace).

Example 10: Preparing and Processing CuBTC in Shaped Form (Extrudates) with Octamethyltrisiloxane

[0112] In the tenth example, a copper-trimesate MOF was prepared and processed in the extruder (Thermofisher Process 11) in shaped form, as follows.

[0113] A mixture of copper (II) hydroxide and trimesic acid (in stoichiometric ratio) was fed into the extruder using a volumetric feeder at a rate of 1.12 g/min. A solution containing a mixture of 18.37 g octamethyltrisiloxane in 100 ml acetone/methanol (85:15) was fed into the extruder at 1.93 mL/min. The mixture was processed through the barrel at 55 rpm. The temperature of the barrel was 25° C. At the end of the barrel a 2 mm die was connected. The extrudate was collected in pellet form (2 mm diameter) and dried overnight under vacuum at room temperature. The BET surface area of the product was determined to be 1056 m.sup.2/g.

Example 11: Preparing and Processing CuBTC in Shaped Form (Extrudates) with Trimethoxyl(Methyl)Silane

[0114] In the eleventh example, a copper-trimesate MOF was prepared and processed in the extruder (Thermofisher Process 11) in shaped form, as follows.

[0115] A mixture of copper (II) hydroxide and trimesic acid (in stoichiometric ratio) was fed into the extruder using a volumetric feeder at a rate of 1.15 g/min. A 100 mL solution containing a mixture of 33.04 g of trimethoxyl(methyl)silane in acetone/methanol (85:15) was fed into the extruder at 2.32 mL/min. The mixture was processed through the barrel at 55 rpm. The temperature of the barrel was 25° C. At the end of the barrel a 2 mm die was connected. The extrudate was collected in pellet form (2 mm diameter) and dried overnight under vacuum at room temperature. The BET surface area of the product was determined to be 1400 m.sup.2/g.

Example 12: Preparing and Processing CuBTC in Shaped Form (Extrudates) with Poly(Dimethylsiloxane)

[0116] In the twelfth example, a copper-trimesate MOF was prepared and processed in the extruder (Thermofisher Process 11) in shaped form, as follows.

[0117] A mixture of copper (II) hydroxide and trimesic acid (in stoichiometric ratio) was fed into the extruder using a volumetric feeder at a rate of 1.15 g/min. A solution containing a mixture of 16.52 g of poly(dimethylsiloxane) in 100 ml of acetone/methanol (85:15) was fed into the extruder at 2.316 mL/min. The mixture was processed through the barrel at 55 rpm. The temperature of the barrel was 25° C. At the end of the barrel a 2 mm die was connected. The extrudate was collected in pellet form (2 mm diameter) and dried overnight under vacuum at room temperature. The BET surface area of the product was determined to be 1113 m.sup.2/g.

Example 13: Hydrothermal Stability Studies CuBTC in Shaped Form (Extrudates) with Octamethyltrisiloxane, Trimethoxyl(Methyl)Silane or Poly(Dimethylsiloxane)

[0118] Commercially available 2 mm Cu-BTC pellets were exposed to 100% relative humidity at 50° C. for 2 days. The BET surface area decreased from 1508 m.sup.2/g to 2 m.sup.2/g.

[0119] Material prepared according to Example 10 was also exposed to 100% relative humidity at 50° C. for 2 days. The BET surface area decreased from 1111 m.sup.2/g to 717 m.sup.2/g.

[0120] Material prepared according to Example 11 was also exposed to 100% relative humidity at 50° C. for 2 days. The BET surface area decreased from 1400 m.sup.2/g to 972 m.sup.2/g.

[0121] Material prepared according to Example 12 was also exposed to 100% relative humidity at 50° C. for 2 days. The BET surface area decreased from 1113 m.sup.2/g to 384 m.sup.2/g.

[0122] This work showed that the decrease in BET surface area was much less for the inventive materials of Examples 10-12 than it was for Cu-BTC.

Example 14: Preparing and Processing CuBTC in Shaped Form (Extrudates) with Poly(Vinyl Pyrrolidone)

[0123] In the fourteenth example, a copper-trimesate MOF was synthesised and processed in the extruder (Thermofisher Process 11), as follows.

[0124] A mixture of copper (II) hydroxide and trimesic acid (in stoichiometric ratio) was fed into the extruder using a volumetric feeder at a rate of 1.37 g/min. A solution containing a mixture of PVP (10.09 g of PVP) in 100 ml of methanol was fed into the extruder at 1.9 mL/min. The mixture was processed through the barrel at 55 rpm. The temperature of the barrel was 25° C. The extrudate was collected and dried overnight under vacuum at room temperature. The BET surface area of the product was determined to be 1369 m.sup.2/g.

Example 15: Hydrothermal Stability Studies of CuBTC with PVP

[0125] Commercially available 2 mm CuBTC pellets were exposed to 100% relative humidity at 50° C. for 2 days. The BET surface area of this material decreased from 1508 m.sup.2/g to 2 m.sup.2/g.

[0126] Material prepared according to Example 14 was also exposed to 100% relative humidity at 50° C. for 2 days. The BET surface area of this material also decreased. However, the decrease for this material was much less, from 1369 m.sup.2/g to 507 m.sup.2/g.

[0127] The BET surface area data for the above Example 14 is shown in FIG. 15. A much more significant decrease is shown for CuBTC than for the material of Example 14.

[0128] N.sub.2 adsorption/desorption isotherms were also measured for the material of Example 14 both before humidity exposure and after exposure to 100% relative humidity at 50° C. for 2 days. The equipment used was a Belsorp Mini II, the N.sub.2 adsorption isotherms being recorded at 77 K. The results are shown in FIG. 16. This shows that the material of Example 16 had a lower, but still useful, adsorption.

[0129] Powder X-ray diffraction data was also collected for the material of Example 17. The equipment used was a Panalytical Aeris. Measurements were made before humidity exposure, as well as after 2 days of exposure to 100% relative humidity at 70° C. This data is shown in FIG. 17. The material of Example 14 shows very little difference between the before exposure sample (bottom trace) and that after 2 days' exposure to humidity (top trace), as all the main characteristic diffraction peaks are still present after the humidity exposure.