Adsorbents with stepped isotherms for gas storage applications

1. An adsorbent having a stepped isotherm comprising a flexible metal-organic framework which has repeating cores comprising the formula M-L-M, wherein L is a linking moiety comprising a structure of Formula I:

wherein,

X 1 -X 6 are each independently a C or a N;

R 1 -R 2 and R 7 -R 8 are each independently selected from the group consisting of H, D, optionally substituted C 1 -C 3 alkyl, optionally substituted C 1 -C 3 alkenyl, halo, hydroxyl, aldehyde, carboxyl, amine, nitrile, azide, and nitro;

R 3 -R 6 are each independently selected from the group consisting of H, D, FG, optionally substituted (C 1 -C 12 )alkyl, optionally substituted hetero-(C 1 -C 12 )alkyl, optionally substituted (C 2 -C 12 )alkenyl, optionally substituted hetero-(C 1 -C 12 )alkenyl, optionally substituted (C 2 -C 12 )alkynyl, optionally substituted hetero-(C 2 -C 12 )alkynyl, optionally substituted cycloalkyl, optionally substituted cycloalkenyl, optionally substituted aryl, optionally substituted heterocycle, optionally substituted mixed ring system, —C(R 11 ) 3 , —CH(R 11 ) 2 , —CH 2 R 11 , —C(R 12 ) 3 , —CH(R 12 ) 2 , —CH 2 R 12 , —OC(R 11 ) 3 , OCH(R 11 ) 2 , —OCH 2 R 11 , —OC(R 12 ) 3 , —OCH(R 12 ) 2 , OCH 2 R 12 , and adjacent R groups can be linked together to form an optionally substituted ring;

R 11 is selected from the group consisting of FG, optionally substituted (C 1 -C 12 )alkyl, optionally substituted hetero-(C 1 -C 12 )alkyl, optionally substituted (C 1 -C 12 )alkenyl, optionally substituted hetero-(C 1 -C 12 )alkenyl, optionally substituted (C 1 -C 12 )alkynyl, optionally substituted hetero-(C 1 -C 12 )alkynyl; and

R 12 is selected from the group consisting of cycloalkyl, aryl and heterocycle; and wherein

M is selected from the group consisting of Be 2+ , Mg 2+ , Ca 2+ , Sr 2+ , Ba 2+ , Sc 2+ , Y 2+ , Ti 2+ , Zr 2+ , V 2+ , Nb 2+ , Ta 2+ , Cr 2+ , Mo 2+ , W 2+ , Re 2+ , Fe 2+ , Ru 2+ , Os 2+ , Rh 2+ , Ir 2+ , Ni 2+ , Pd 2+ , Pt 2+ , Cu 2+ , Ag 2+ , Au 2+ , Hg 2+ , Al 2 , In 2+ , Si 2+ , Ge 2+ , Sn 2+ , Pb 2+ , As 2+ , Te 2+ , La 2+ , Ce 2+ , Pr 2+ , Nd 2+ , Sm 2+ , Eu 2+ , Gd 2+ , Tb 2+ , Db 2+ , Tm 2+ , Yb 2+ , La 2+ , and combinations thereof, including any complexes which contain the metals or metal ions, as well as any corresponding metal salt counter-anions;

wherein tetrahedrally or pseudo-tetrahedrally M is bridged by μ 2 -pyrazolate units of L; and

wherein M is selected from the croup consisting of Mg 2+ , Ca 2+ , Ba 2+ , Zr 2+ , V 2+ , Cr 2+ , Mo 2+ , W 2+ , Fe 2+ , Ni 2+ , Cu 2+ , and Ce 2+ .

2. The adsorbent of claim 1 , wherein L comprises a structure of Formula I(a):

wherein,

R 3 -R 6 are each independently selected from the group consisting of H, D, halos, hydroxyls, carboxyls, carbonates, carboxylates, aldehydes, esters, ethers, amines, amides, azides, nitriles, sulfides, nitros, optionally substituted (C 1 -C 6 )alkyl, optionally substituted hetero-(C 1 -C 6 )alkyl, optionally substituted (C 2 -C 6 )alkenyl, optionally substituted hetero-(C 1 -C 6 )alkenyl, optionally substituted (C 2 -C 6 )alkynyl, optionally substituted hetero-(C 2 -C 6 )alkynyl.

3. The adsorbent of claim 2 , wherein L comprises a structure of Formula I(b):

4. The adsorbent of claim 1 , wherein M is Fe 2+ .

5. A gas storage device comprising an adsorbent of claim 1 .

6. The gas storage device of claim 5 , wherein L is a linking moiety comprising a structure of Formula I(b)

and wherein M is selected from the group consisting of Mg 2+ , Ca 2+ , Ba 2+ , Zr 2+ , V 2+ , Cr 2+ , Co 2+ , Mo 2+ , W 2+ , Fe 2+ , Ni 2+ , Cu 2+ , and Ce 2+ .

7. The adsorbent of claim 1 , wherein the adsorbent's volumetric usable capacity is (i) not significantly reduced when there is a minimum desorption pressure requirement, (ii) not significantly reduced due to heat released during adsorption of the one or more gases to the adsorbent, and/or (iii) is not significantly reduced due to cooling resulting from de-adsorption of the one or more gases from the adsorbent.

8. The adsorbent of claim 1 , wherein the minimum desorption pressure requirement is around 5.8 bar and the one or more gases is a natural gas.

9. The absorbent or device of claim 8 , wherein natural gas is adsorbed under an adsorption pressure between 35 and 65 bar.

10. The device of claim 5 , wherein the one or more gases are selected from natural gas, hydrogen or methane.

11. The device of claim 5 , wherein the device is a fuel tank or fuel cylinder.

12. The device of claim 11 , wherein the fuel tank or fuel cylinder delivers stored natural gas, methane or hydrogen to a combustion engine.

13. An automobile, bus, or truck comprising the device of claim 11 .

14. A method to reversibly store one or more gases comprising contacting the one or more gases with the adsorbent of claim 1 .

15. The method of claim 14 , wherein L comprises a structure of Formula I(a):

wherein,

R 3 -R 6 are each independently selected from the group consisting of H, D, halos, hydroxyls, carboxyls, carbonates, carboxylates, aldehydes, esters, ethers, amines, amides, azides, nitriles, sulfides, nitros, optionally substituted (C 1 -C 6 )alkyl, optionally substituted hetero-(C 1 -C 6 )alkyl, optionally substituted (C 2 -C 6 )alkenyl, optionally substituted hetero-(C 1 -C 6 )alkenyl, optionally substituted (C 2 -C 6 )alkynyl, optionally substituted hetero-(C 2 -C 6 )alkynyl.

16. The method of claim 15 , wherein L comprises a structure of Formula I(b):

17. The method claim 14 , wherein M is selected from the group consisting of Mg 2+ , Ca 2+ , Ba 2+ , Zr 2+ , V 2+ , Cr 2+ , Mo 2+ , W 2+ , Fe 2+ , Ni 2+ , Cu 2+ , Co 2+ and Ce 2+ .

18. The method of claim 17 , wherein M is Fe 2+ or Co 2+ .

19. The method claim 14 , wherein the one or more gases are selected from natural gas, hydrogen or methane.