Method for storing a gas in a metal organic framework and dissolved in a liquid carrier

Abstract

The invention relates a method for storing a solution of methane and a C2-C30 hydrocarbon, the method comprising: mixing gaseous methane and a C2-C30 hydrocarbon to provide a mixture of methane and C2-C30 hydrocarbon, wherein the mixture comprises greater than or equal to about 50 mole percent of methane; maintaining the mixture of methane and C2-C30 hydrocarbon as a liquid solution at a pressure of 30 to 150 bar within a storage vessel, wherein the storage vessel comprises a porous adsorbent framework. The invention also relates to similar methods for storing hydrogen, nitrogen and carbon dioxide. The invention also relates to the use of a non-polar solvent such as a hydrocarbon for storing a non-polar gas in a porous adsorbent framework.

Claims

1. A method of storing a solution of methane and a C2-C30 hydrocarbon, the method comprising: mixing gaseous methane and a C2-C30 hydrocarbon to provide a mixture of methane and C2-C30 hydrocarbon, wherein the mixture comprises greater than or equal to about 50 mole percent of methane; maintaining the mixture of methane and C2-C30 hydrocarbon as a liquid solution at a pressure of 30 to 150 bar within a storage vessel, wherein the storage vessel comprises a porous adsorbent framework, and wherein the porous adsorbent framework is a metal organic framework.

2. The method according to claim 1, wherein the solution of methane and C2-C30 hydrocarbon is adsorbed in the porous adsorbent material.

3. The method according to claim 1, wherein mixing gaseous methane and a C2-C30 hydrocarbon comprises feeding a C2-C30 hydrocarbon into the storage vessel comprising the porous adsorbent framework, and then feeding methane into the storage vessel to produce a mixture of methane and C2-C30 hydrocarbon.

4. The method according to claim 1, wherein mixing gaseous methane and a C2-C30 hydrocarbon is carried out before the mixture of methane and C2-C30 hydrocarbon is fed into the storage vessel.

5. The method according to claim 1, wherein the mixture of methane and C2-C30 hydrocarbon comprises from about 50 to about 80 mole percent of methane, and wherein the solution of methane and C2-C30 hydrocarbon is maintained at a pressure below the vapour pressure of the C2-C30 hydrocarbon.

6. The method according to claim 1, wherein the C2-C30 hydrocarbon is fed into the storage vessel at a pressure below the vapour pressure of the C2-C30 hydrocarbon.

7. The method according to claim 1, further comprising releasing the methane from the storage vessel.

8. The method according to claim 7, wherein the methane is released without releasing the C2-C30 hydrocarbon from the storage vessel.

9. The method according to claim 8, wherein the methane is released to a pressure of about atmospheric pressure to 5 bar pressure.

10. The method according to claim 1, wherein the metal organic framework comprises molecular pores having a pore diameter of over 3.8 Angstroms.

11. The method according to claim 1, wherein the metal organic framework comprises bi-, tri-, or tetra-carboxylate ligands.

12. The method according to claim 11, wherein the metal organic framework is UiO-66, UiO-67, PCN-250 or PCN-777.

13. The method according to claim 1, wherein the C2-C30 hydrocarbon is propane and optionally the propane is fed to the storage vessel at a pressure of less than 117 psi, less than or equal to 100 psi, less than or equal to 80 psi, or less than or equal to 60 psi; or wherein the C2-C30 hydrocarbon is n-butane and optionally the n-butane is fed to the storage vessel at a pressure of less than 20 psi, less than or equal to 15 psi, less than or equal to 12 psi, or less than or equal to 10 psi; or wherein C2-C30 hydrocarbon is n-hexane and optionally the n-hexane is fed to the storage vessel at a volume of less than 120 L, less than or equal to 60 L, less than or equal to 30 L; or wherein the C2-C30 hydrocarbon is n-octane and optionally the n-octane is fed to the storage vessel at a volume of less than 120 L, less than or equal to 60 L, less than or equal to 30 L; or wherein the C2-C30 hydrocarbon is n-decane and optionally the n-decane is fed to the storage vessel at a volume of less than 120 L, less than or equal to 60 L, less than or equal to 30 L; or wherein the C2-C30 hydrocarbon is cyclodecane and optionally the cyclodecane is fed to the storage vessel at a volume of less than 120 L, less than or equal to 60 L, less than or equal to 30 L.

14. The method according to claim 1, wherein the hydrocarbon is a C2-C10 hydrocarbon.

15. A method of storing a solution of hydrogen and a C2-C30 hydrocarbon, the method comprising: mixing gaseous hydrogen and a C2-C30 hydrocarbon to provide a mixture of hydrogen and C2-C30 hydrocarbon, wherein the mixture comprises greater than or equal to about 50 mole percent of hydrogen; maintaining the mixture of hydrogen and C2-C30 hydrocarbon as a liquid solution at a pressure of 30 to 150 bar within a storage vessel, wherein the storage vessel comprises a porous adsorbent framework, and wherein the porous adsorbent framework is a metal organic framework.

16. The method according to claim 15, further comprising releasing the hydrogen from the storage vessel.

17. The method according to claim 16, wherein the hydrogen is released without releasing the C2-C30 hydrocarbon from the storage vessel.

18. The method according to claim 15, wherein the metal organic framework comprises molecular pores having a pore diameter of over 3.8 Angstroms.

19. The method according to claim 15, wherein the C2-C30 hydrocarbon is propane and optionally the propane is fed to the storage vessel at a pressure of less than 117 psi, less than or equal to 100 psi, less than or equal to 80 psi, or less than or equal to 60 psi.

20. A method for storing a solution of carbon dioxide or nitrogen and a C2-C30 hydrocarbon, the method comprising: mixing gaseous carbon dioxide or nitrogen and a C2-C30 hydrocarbon to provide a mixture of carbon dioxide or nitrogen and C2-C30 hydrocarbon, wherein the mixture comprises greater than or equal to about 50 mole percent of carbon dioxide or nitrogen; maintaining the mixture of carbon dioxide or nitrogen and C2-C30 hydrocarbon as a liquid solution at a pressure of 30 to 150 bar within a storage vessel, wherein the storage vessel comprises a porous adsorbent framework, and wherein the porous adsorbent framework is a metal organic framework.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) FIG. 1 is a GC chromatogram comparing desorbed methane from a metal organic framework (UiO-66) in the presence and absence of propane.

(2) FIG. 2 is a GC chromatogram comparing desorbed methane from a metal organic framework (UiO-67) in the presence and absence of n-butane.

(3) FIG. 3 is a graph showing methane absorption of PCN-250 with and without the use of n-decane.

(4) FIG. 4 is a graph showing methane absorption of UiO-66 with and without the use of cyclodecane.

(5) FIG. 5 is a graph showing methane absorption of PCN-777 with and without the use of n-dodecane.

(6) FIG. 6 is a graph showing methane absorption of UiO-66 with and without the use of propane.

(7) FIGS. 7a-7c illustrate the meanings of the terms free diameter, pore opening, and pore volume. The term void volume is employed to mean the pore volume minus trapped solvent volume. FIG. 7a illustrates the meaning of the term free diameter. FIG. 7b illustrates the meaning of the term pore opening. FIG. 7e illustrates the meaning of the term pore volume.

EXAMPLES

(8) Tests were conducted to evaluate if hydrocarbons could enhance uptake of natural gas in porous sorbents.

Example 1

(9) The test sorbents were exposed to selected hydrocarbons (alkanes) at room temperature, below their vapor pressure. Following, methane gas was adsorbed at 65 bar. The concept is based on the high solubility of methane in alkane species. Over their vapor pressure, selected alkanes (propane and n-butane) changed phase from gas to liquid state within the pores of the test adsorbents and increased adsorbent's methane uptake by dissolving adsorbed gaseous methane. This novel approach provided a new mechanism for methane uptake in addition to the physisorption mechanism.

(10) The test system is composed of two subsystems: (i) gas uptake subsystem, (ii) gas analysis subsystem.

(11) The gas uptake subsystem includes test gases, fluid system components, electrical connections and sensors. The gas analysis subsystem includes gas chromatograph with a flame ionization detector (FID), chromatograph column, GC carrier gas, GC hydrogen gas and fluid system connections.

(12) Using the gas uptake test system, the test gases were accumulated in a 500 ml stainless steel container before they were exposed to the adsorbent. The container was composed of two NPT ports for integration of a pressure transducer and for connecting to a stainless steel column, which held the tested adsorbent. Gas flow from the container was made while isolating the gas from the source (gas cylinder) by attaching a three-way valve at the container's outlet.

(13) The gas uptake tests were conducted in two steps. First, the selected alkane gas was accumulated in the container and the pressure was recorded by the pressure transducer. Following, the tested adsorbent was exposed to the accumulated alkane gas by directing the three-way valve towards the stainless steel test column. The test column volume was 1 ml, which was sufficient to store 220-260 mg of adsorbent (UIO-66 and UIO-67). After exposure to the alkane gas, methane gas set at 65 bar was directed to the test column. Each adsorption step took 15 minutes, during this time frame pressure drop in the test column was observed representing gas uptake by the adsorbent.

(14) Following the gas uptake test, the test column at high pressure (60-65 bar) was removed from the container and connected to a gas chromatograph's sample port. The gas chromatograph was equipped with a capillary column, which was specific to the hydrocarbons tested. The amount of gas released to atmospheric pressure was quantified by the gas chromatograph and test results were reported as follows:

(15) TABLE-US-00001 GC Integration Area (GCIA) n- GCIA W Methane Propane butane CH.sub.4 [W/W.sub.0] UIO-66 (258.4 mg) W[g] (CH.sub.4) (C.sub.3H.sub.8) (C.sub.4H.sub.10) [A/A.sub.0] (%) (%) Desorbed 4 hrs at 70 deg C. 95.504 388528 0 0.00% 0.07% Adsorbed (Methane only at 65 bar) 95.5749 Desorbed 4 hrs at 70 deg C. 95.5036 458581 268024 0 18.03% 0.10% Adsorbed (Propane at 60 PSI 95.6029 and methane at 65 bar) Desorbed 4 hrs at 70 deg C. 95.5037 372874 0 17109 4.03% 0.10% Adsorbed (n-butane at 20 PSI 95.597 and methane at 65 bar) Desorbed 4 hrs at 70 deg C. 95.5041 255538 530136 34.23% 0.12% Adsorbed (Propane at 117 PSI 95.615 and methane at 65 bar) UIO-67 (224.3 mg) Desorbed 4 hrs at 120 deg C. 92.2765 412157 0 0.00% 0.08% Adsorbed (Methane only at 65 bar) 92.3525 Desorbed 4 hrs at 120 deg C. 92.2741 328074 281006 0 20.40% 0.13% Adsorbed (Propane at 60 PSI 92.3928 and methane at 65 bar) Desorbed 4 hrs at 120 deg C. 92.2734 408346 0 27795 0.92% 0.12% Adsorbed (n-butane at 20 PSI 92.3807 and methane at 65 bar) Desorbed 3 hrs at 120 deg C. 92.2736 435496 0 11733 7.11% 0.09% Adsorbed (n-butane at 10 PSI 92.3591 and methane at 65 bar) note 1: the highest pressure of propane at room temperature and 1 atm pressure is 117 PSI note 2: the highest pressure of n-butane at room temperature and 1 atm pressure is 20 PSI

(16) When the GC chromatograms are analyzed, it can be seen that besides the GC integration area or pA (peak area) difference, the intensity of the elution signals are also different in magnitude (labeled X FIG. 1 and FIG. 2). Specifically, the UIO-66 sorbent desorbed gas analysis shows that the pA intensities are different in magnitude indicating the difference in deliverable methane capacity with and without the use of propane gas. In FIG. 1, the diamond data points represent UiO-66 test with propane; the circular data points represent UiO-66 without propane. In FIG. 2, the diamond data points represent UiO-67 with n-butane; the circular data points represent UiO-67 without n-butane. Another interesting fact is the time difference between the eluted gas species when propane is used to enhance the methane uptake capacity of the MOF sorbent. FIG. 1 UIO-66 desorbed gas analysis with propane graph shows two peaks. The lesser retained, lighter methane molecules are eluted completely before the higher molecular weight propane gas is off-gassed from the MOF sorbent. Similarly, in FIG. 2, UIO-67's GC chromatogram shows an increase in deliverable methane capacity when n-butane is used to flush the sorption column before methane gas was introduced at 65 bar pressure. In addition, the elution time difference of different species is more evident when n-butane is used. This behavior is likely due to the higher molecular weight of n-butane when compared to propane and methane molecules. Lesser retained, more volatile and lighter weight molecules are eluted from the MOF sorbent faster before the molecules with less vapor pressure are released.

(17) Below is set out the testing procedure regarding the lightweight gaseous hydrocarbons (e.g. C.sub.3 and C.sub.4 alkanes) and heavier-weight liquid hydrocarbons (e.g. C.sub.6-C.sub.10):

(18) A. Gaseous Alkane (C.sub.3 and C.sub.4 Alkanes) Test Description:

(19) Fluidic System Purge/Clean-up: Initially, before the hydrocarbon injection, the test system is purged with an inert gas to remove all the atmospheric impurities including water vapor. To accomplish the inert gas purge, the canister is purged with 50 psig UHP Nitrogen gas three times using the 3-way valve of the test set-up. At the end of the last purge, the needle valve of the test set-up is closed to seal the system from water vapor. Following the inert gas purge, the selected lightweight hydrocarbon (propane or n-butane) pressurized gas cylinder is connected to the 3-way valve inlet and the charger canister is filled with the test gas over atmospheric pressure to prevent contamination from outside. After the canister is charged, the 3-way valve flow is directed towards the purge line and the purge gas is replaced with the selected hydrocarbon gas in the test system.

(20) Gaseous Alkane Injection: After purging the test system with the selected alkane gas (C.sub.3 and C.sub.4 alkanes), the test canister is charged to the selected gas pressure. The C.sub.3 gas pressure is selected according to the maximum storage pressure of propane at ambient temperature and half of the amount of this test pressure. These values are 117 psig and 60 psig for propane gas and 20 and 10 psi for n-butane gas. After the test canister is charged to the desired test pressures, the gas is directed to the regenerated MOF sorbent while the system pressure dropdue to adsorption, is recorded. Following a 10-minute test duration, the test cell is disconnected from the test set-up and its weight gaindue to adsorption, is recorded.

(21) High Pressure Methane Injection: Following the weight measurement of the test cell, it is re-connected to the test system for the last time for the high-pressure methane uptake step. After purging the test system with methane gas to remove the alkane gas impurities, the test canister is charged to the selected ANG test pressure (65 bar pressure). Following, the gas is directed to the alkane-loaded-MOF-sorbent while the system pressure dropdue to methane adsorption, is recorded. Immediately after a 10-minute test duration, the test cell is disconnected from the test set-up and its weight gaindue to methane adsorption, is recorded.

(22) Gas Chromatography Measurements: Following the methane uptake test, the adsorbed gas is injected to a GC column integrated to a flame-ionization detector to measure the concentration of the methane gas desorbed from the test cell at ambient pressure.

(23) B. Liquid Alkane (C6-C10 Alkanes) Test Description:

(24) Fluidic System Purge/Clean-up: Initially, before the hydrocarbon injection, the test system is purged with an inert gas to remove all the atmospheric impurities including water vapor. Following the inert gas purge, the test system is sealed by a ball valve located in between the system and the test cell.

(25) Liquid Alkane Injection: While the test cell is sealed, liquid alkane is injected directly to the headspace of the test cell. This volume is enough to store 120 microliters of the tested liquid alkane chemical. With the alkane in its headspace, the test cell is connected to the ball valve of the test system.

(26) High Pressure Methane Injection: After purging the test system with methane gas to remove the alkane gas impurities, the test canister is charged to the selected ANG test pressure (65 bar pressure). Following, the gas is directed to the MOF sorbent while carrying the liquid alkane in its pathway. Immediately after a 10-minute test duration, the test cell is disconnected from the test set-up and its weight gaindue to methane adsorption, is recorded.

(27) Gas Chromatography Measurements: Following the methane uptake test, the adsorbed gas is injected to a GC column integrated to a flame-ionization detector to measure the concentration of the methane gas desorbed from the test cell at ambient pressure.

(28) C. Liquid Alkane (C6-C10 Alkanes) with Hydrogen Test Description:

(29) Fluidic System Purge/Clean-up: Initially, before the hydrocarbon injection, the test system is purged with an inert gas to remove all the atmospheric impurities including water vapor. Following the inert gas purge, the test system is sealed by a ball valve located in between the system and the test cell.

(30) Liquid Alkane Injection: While the test cell is sealed, liquid alkane is injected directly to the headspace of the test cell. This volume is enough to store 120 microliters of the tested liquid alkane chemical. With the alkane in its headspace, the test cell is connected to the ball valve of the test system.

(31) High Pressure Methane Injection: After purging the test system with methane gas to remove the alkane gas impurities, the test canister is charged to the selected ANG test pressure (65 bar pressure). Following, the gas is directed to the MOF sorbent while carrying the liquid alkane in its pathway. Immediately after a 10-minute test duration, the test cell is disconnected from the test set-up and its weight gaindue to methane adsorption, is recorded. The hydrogen adsorption is determined by measuring the pressure drop in the test system due to hydrogen uptake of the MOF sorbent with and without the tested liquid alkane sorbent.

Example 2: Methane Uptake (n-Decane & PCN-250)

(32) PCN-250 is a molecular organic framework described in international patent application no. PCT/GB2014/053506 (hereby incorporated by reference in its entirety). PCN-250 is a channel type MOF. Its synthesis is repeated here:

(33) Synthesis of PCN-250 (Fe.sub.3):

(34) ##STR00001##

(35) L22 (10 mg), Fe.sub.3O(CH.sub.3COO).sub.6 (15 mg) and acetic acid (1 ml) in 2 mL of DMF were ultrasonically dissolved in a Pyrex vial. The mixture was heated in 140 C. oven for 12 h. After cooling down to room temperature, dark brown crystals were harvested by filtration (Yield. 80%).

(36) The synthesis of L22 was carried out in accordance with Wang, X.-S.; Ma, S.; Rauch, K.; Simmons, J. M.; Yuan, D.; Wang, X.; Yildirim, T.; Cole, W. C.; Lopez, J. J.; de Meij ere, A.; Zhou, H.-C. Metal-organic frameworks based on double-bond-coupled di-isophthalate linkers with high hydrogen and methane uptakes, Chemistry of Materials 2008, 20, 3145 (hereby incorporated in its entirety by reference).

(37) The uptake of methane was measured using the test procedure B described above using PCN-250 as porous adsorbent material and n-decane as the hydrocarbon. The results are shown in FIG. 3. The control referred to in FIG. 3 is the same test procedure performed without the use of n-decane. The square data points represent methane uptake without n-decane. The triangular data points represent methane uptake using n-decane.

(38) FIG. 3 demonstrates the improved methane adsorption observed when PCN-250 is employed as the porous adsorbent material in connection with n-decane as the hydrocarbon solvent. As seen in FIG. 3, a significant improvement in methane adsorption is observed.

Example 3: Methane Uptake (Cyclodecane & UiO-66)

(39) UiO-66 is a zirconium molecular organic framework described in international patent application no. PCT/GB2009/001087published as WO2009/133366 (hereby incorporated by reference in its entirety). UiO-66 is a cage type MOF.

(40) The uptake of methane was measured using the test procedure B described above using UiO-66 as porous adsorbent material and cyclodecane as the hydrocarbon. The results are shown in FIG. 4. The square data points represent methane uptake without cyclodecane. The triangular data points represent methane uptake with cyclodecane.

(41) FIG. 4 demonstrates the improved methane adsorption observed when UiO-66 is used as the porous adsorbent material and cyclo-decane is employed as the hydrocarbon. As seen from FIG. 4, a significant increase in methane adsorption is observed.

Example 4: Methane Uptake (n-Dodecane & PCN-777)

(42) PCN-777 is zirconium containing molecular organic framework described by Feng et al in Angew. Chem. Int. Ed. 2014, 53, 1-7 (hereby incorporated by reference in its entirety). PCN-777 is a channel type MOF.

(43) The uptake of methane was measured using the test procedure B described above using PCN-777 as porous adsorbent material and n-dodecane as the hydrocarbon. The results are shown in FIG. 5. The square data points represent methane uptake without n-dodecane. The triangular data points represent methane uptake using n-dodecane.

(44) FIG. 5 demonstrates the improved methane adsorption observed when PCN-777 is employed as the porous adsorbent material and dodecane is employed as the hydrocarbon. As seen in FIG. 5, a significant increase in methane adsorption is observed.

Example 5: Methane Uptake (Propane & UiO-66)

(45) The uptake of methane was measured using the test procedure A described above using UiO-66 as porous adsorbent material and propane as the hydrocarbon. The results are shown in FIG. 6. The square data points represent methane uptake without propane (i.e. the control). The triangular data points represent methane uptake using propane.

(46) FIG. 6 demonstrates the improved methane adsorption observed when UiO-66 is employed as the porous adsorbent material and propane is employed as the hydrocarbon. As seen in FIG. 6, a significant increase in methane adsorption is observed.