# US 11,896,951 B2 · Mixed-metal strategy for the fast synthesis of metal-organic frameworks under ambient conditions

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- Number: US 11,896,951 B2
- Document ID: US11896951B2
- Status: Granted
- Kind: B2
- Application number: 17/998,510
- Filed: 2021-04-19
- Published: 2023-06-22
- Granted: 2024-02-13
- Earliest claimed: 2020-05-12
- Assignees: National University of Singapore
- Applicants: National University of Singapore
- Inventors: Dan Zhao; Shing Bo Peh; Avishek Karmakar
- Web page: https://patentgrep.com/patent/US11896951B2

## CPC

- B01J 20/226: {Coordination polymers, e.g. metal-organic frameworks [MOF], zeolitic imidazolate frameworks [ZIF] (preparation of metal complexes containing carboxylic acid moieties C07C51/418; MOF's per se C07F)}
- B01D 53/02: by adsorption, e.g. preparative gas chromatography {(solid sorbent compositions B01J20/00, preparation of inorganic compounds or elements C01)}
- B01D 53/04: with stationary adsorbents {(B01D53/025 takes precedence)}
- B01J 20/28011: {Other properties, e.g. density, crush strength}
- B01J 20/28057: {Surface area, e.g. B.E.T specific surface area}
- B01J 20/3085: {Chemical treatments not covered by groups B01J20/3007 - B01J20/3078}
- C07F 15/065: {without a metal-carbon linkage}
- B01D 2253/204: Metal organic frameworks (MOF's)
- B01D 2257/504: Carbon dioxide
- B01D 2258/0283: Flue gases
- Y02C 20/40: of CO2
- B01J: CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28)
- C07F: ACYCLIC, CARBOCYCLIC OR HETEROCYCLIC COMPOUNDS CONTAINING ELEMENTS OTHER THAN CARBON, HYDROGEN, HALOGEN, OXYGEN, NITROGEN, SULFUR, SELENIUM OR TELLURIUM (metal-containing porphyrins C07D487/22)
- Y02C: CAPTURE, STORAGE, SEQUESTRATION OR DISPOSAL OF GREENHOUSE GASES [GHG]

## Abstract

Disclosed herein is a metal organic framework (MOF) having a UTSA-16 structure, where the composition comprises: from 0 to 80 mol % of the total metal in the MOF is a first metal selected from one or more of the group consisting of Cr, Mn, Fe, Ni, Cu, and Co; and from 20 to 100 mol % of the total metal in the MOF is a second metal selected from one or more of the group consisting of Cd, Mn, and Zn.

## Claims

### Claim 1

A metal organic framework (MOF) having a UTSA-16 structure, where the MOF comprises a first metal selected from one or more of the group consisting of Cr, Fe, Ni, Cu, and Co, wherein the first metal represents up to 80 mol % of the total metal in the MOF; and from 20 to 80 mol % of the total metal in the MOF is a second metal selected from one or more of the group consisting of Cd, Mn, and Zn, wherein the MOF comprises tetrahedral metal sites and a majority of the second metal occupies the tetrahedral metal sites within the MOF.

### Claim 2 (depends on 1)

The MOF according to claim 1, wherein the second metal is Zn.

### Claim 3 (depends on 1)

The MOF according to claim 1, wherein the second metal is present in an amount of from 50 to 75 mol % of the total metal present in the MOF.

### Claim 4 (depends on 1)

The MOF according to claim 1, wherein the first metal is selected from Fe and Co.

### Claim 5 (depends on 1)

The MOF according to claim 1, wherein the first metal is Co.

### Claim 6 (depends on 1)

The MOF according to claim 1, wherein the first metal is present in an amount of from 25 to 50 mol % of the total metal present in the MOF.

### Claim 7 (depends on 1)

The MOF according to claim 1, wherein the MOF comprises octahedral metal sites and a majority of the first metal occupies the octahedral metal sites within the MOF.

### Claim 8 (depends on 1)

The MOF according to claim 1, wherein the MOF has a saturated CO2 uptake of up to 5.0 mmol/g.

### Claim 9 (depends on 1)

The MOF according to claim 1, wherein the MOF has a breakthrough CO2 working capacity of up to 2.2 mmol/g.

### Claim 10 (depends on 1)

A method of capturing CO2 comprising the step of exposing a material comprising a MOF as described in claim 1 to an environment containing CO2.

### Claim 11 (depends on 1)

The MOF according to claim 1, wherein 51 mol % or more of the second metal occupies the tetrahedral metal sites within the MOF.

### Claim 12 (depends on 1)

The MOF according to claim 1, wherein 60 mol % of the second metal occupies the tetrahedral metal sites within the MOF.

### Claim 13 (depends on 1)

A method of forming the MOF of claim 1, the method comprising:
aging a mixture comprising a first metal precursor, a second metal precursor, a base, citric acid, a first solvent, and a second solvent for a period of time at a temperature of 15° C. to 200° C.,
wherein the first metal precursor comprises a first metal that is selected from Cr, Fe, Ni, Cu, Co, and any combination thereof,
wherein the second metal precursor comprises a second metal that is selected from Cd, Mn, Zn, and any combination thereof,
wherein the first metal is present in an amount up to 80 mol % of the total amount of metal in the mixture, and
wherein the second metal is present in an amount from 20 to 80 mol % of the total amount of metal in the mixture.

### Claim 14 (depends on 13)

The method of claim 13, wherein the temperature is from 20 to 150° C.

### Claim 15 (depends on 13)

The method of claim 13, wherein the temperature is from 40 to 120° C.

### Claim 16 (depends on 13)

The method of claim 13, wherein the temperature is from 60 to 80° C.

### Claim 17 (depends on 13)

The method of claim 13, wherein:
(a) the first solvent is water and the second solvent is an alkyl alcohol;
(b) the base is a metal hydroxide; and/or
(c) the method is performed under ambient atmospheric conditions.

### Claim 18 (depends on 13)

The method of claim 13, wherein the first and second metal precursors are each a metal salt, wherein the first and second metals in the metal salt are each in a cationic form that is balanced by one or more counterions that are each independently selected from a halide, nitrate, sulfate, hydroxide, oxide, acetate anion, hydrate, and any combination thereof.

### Claim 19 (depends on 13)

The method of claim 13, wherein:
(a) the second metal precursor is Zn(OAc)2 or a hydrate thereof; and/or
(b) the second metal in the second metal precursor is present in an amount of from 50 to 75 mol % of the total amount of metal in the mixture.

### Claim 20 (depends on 13)

The method of claim 13, wherein:
(a) the first metal precursor is Fe(OAc)2, Co(OAc)2 or a hydrate thereof; and/or
(b) the first metal in the first metal precursor is present in an amount of from 25 to 50 mol % of the total amount of metal in the mixture.