Preparation method for zeolitic imidazolate frameworks

Abstract

The present invention provides a preparation method for zeolitic imidazolate frameworks. The preparation method comprises: adding a metal carbonate or oxide, an organic ligand to a hydrophilic liquid to obtain a mixture; introducing an acidic gas to reach a reaction pressure of 0.1 MPa to 2.0 MPa, and reacting for a predetermined time; heating to 30 C.-60 C. and vacuuming to obtain the zeolitic imidazolate framework. The present invention also provides a zeolitic imidazolate framework obtained by the above preparation method. The preparation method according to the present invention is environmentally friendly and has a high yield.

Claims

1. A method for preparing a zeolitic imidazolate framework, characterized in that the method comprises the following steps: Step 1: adding a metal carbonate or oxide and an organic ligand to a hydrophilic liquid to obtain a mixture; Step 2: introducing an acidic gas to reach a reaction pressure of 0.1 MPa to 2.0 MPa, maintaining the pressure for 30 to 60 minutes, and terminating the reaction; Step 3: heating to 30 C.60 C. and vacuuming to obtain the zeolitic imidazolate framework, wherein the hydrophilic liquid comprises one or a combination of two or more of water, an alcohol, and an amide; wherein the acidic gas is CO.sub.2, H.sub.2S, SO.sub.2, or NO.sub.2; and wherein the organic ligand is selected from the group consisting of one or a combination of two or more of imidazole, 2-methylimidazole, 2-ethylimidazole, 2-propylimidazole, and benzimidazole.

2. The preparation method according to claim 1, characterized in that a mass ratio of the metal carbonate or oxide to the hydrophilic liquid is 1:2 to 1:100.

3. The preparation method according to claim 1, characterized in that a molar ratio of the metal atom in the metal carbonate or oxide to the organic ligand is 1:2 to 1:10.

4. The preparation method according to claim 1, characterized in that the hydrophilic liquid comprises water, an aqueous solution of an alcohol, an aqueous solution of an amide, or an alcoholic solution of an amide.

5. The preparation method according to claim 4, characterized in that the alcohol comprises methanol, ethanol, ethylene glycol, or triethylene glycol.

6. The preparation method according to claim 4, characterized in that the amide comprises N,N-dimethylformamide, N,N-dimethylacetamide, or N,N-diethylformamide.

7. The preparation method according to claim 1, characterized in that Steps 1 and 2 are carried out at 10 C. to 40 C.

8. The preparation method according to claim 1, characterized in that the metal carbonate or oxide is selected from the group consisting of one or a combination of two of basic zinc carbonate, cobalt carbonate, zinc oxide, and cobalt oxide.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is an X-ray diffraction (XRD) pattern of a ZIFs crystal synthesized in Example 1 of the present invention.

(2) FIG. 2 is an X-ray diffraction (XRD) pattern of a ZIFs crystal synthesized in Example 2 of the present invention.

(3) FIG. 3 is an X-ray diffraction (XRD) pattern of a ZIFs crystal synthesized in Example 3 of the present invention.

(4) FIG. 4 is an X-ray diffraction (XRD) pattern of a ZIFs crystal synthesized in Example 4 of the present invention.

(5) FIG. 5 is an X-ray diffraction (XRD) pattern of a ZIFs crystal synthesized in Example 5 of the present invention.

(6) FIG. 6 is an X-ray diffraction (XRD) pattern of a ZIFs crystal synthesized in Example 6 of the present invention.

(7) FIG. 7 is an X-ray diffraction (XRD) pattern of a ZIFs crystal synthesized in Example 7 of the present invention.

(8) FIG. 8 is an X-ray diffraction (XRD) pattern of a ZIFs crystal synthesized in Example 8 of the present invention.

(9) FIG. 9 is an X-ray diffraction (XRD) pattern of a ZIFs crystal synthesized in Example 9 of the present invention.

(10) FIG. 10 is a mass spectrum in the process for synthesizing a ZIFs crystal according to Example 10 of the present invention.

(11) FIG. 11 is an X-ray diffraction (XRD) pattern of a ZIFs crystal synthesized in Example 12 of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

(12) In order to more clearly understand the technical features, objects, and advantageous effects of the present invention, the technical solutions of the present invention are described in detail below, but are not to be construed as limiting the implementable scope of the present invention.

Example 1

(13) This example provided a method for preparing a zeolitic imidazolate framework, comprising the following steps:

(14) 1.6843 g of basic zinc carbonate [ZnCO.sub.3.2Zn(OH).sub.2.H.sub.2O] and 7.5294 g of 2-methylimidazole were dissolved in a mixed solution of 7.5885 g of water and 7.5470 g of ethylene glycol, and stirred uniformly;

(15) carbon dioxide was introduced at 25 C. to reach an equilibrium pressure of 0.54 MPa, and the pressure was maintained for 30 minutes, and the reaction was terminated;

(16) then the reactor was heated to 40 C., and vacuumed to remove carbon dioxide;

(17) after CO.sub.2 was removed, the solid-liquid mixture was separated by filtration, and the solid phase product was placed in a vacuum drying oven, dried and activated to obtain a ZIF-8 crystal, and finally the filtrate was recycled and reused for the next cycle.

(18) The XRD peak shape of the ZIF-8 crystal of the example is shown in FIG. 1, which is consistent with the literature report (Yaghi et al, Exceptional chemical and thermal stability of zeolitic imidazolate frameworks, PNAS, 2006, 103 (27):10186-10191). The yield of the ZIF-8 of the example was 93%.

Example 2

(19) This example provided a method for preparing a zeolitic imidazolate framework, comprising the following steps:

(20) 1.7105 g of zinc oxide and 4.1258 g of 2-methylimidazole were dissolved in 15.0052 g of methanol, and stirred uniformly;

(21) sulfur dioxide was introduced at 20 C. to reach an equilibrium pressure of 0.65 MPa, and the pressure was maintained for 35 minutes, and the reaction was terminated;

(22) the reactor was heated to 50 C., and vacuumed to remove sulfur dioxide;

(23) after SO.sub.2 was removed, the solid-liquid mixture was separated by filtration, and the solid phase product was placed in a vacuum drying oven, dried and activated to obtain a ZIF-8 crystal, and finally the filtrate was recycled and reused for the next cycle.

(24) The XRD peak shape of the ZIF-8 crystal of the example is shown in FIG. 2, which is consistent with the literature report (Yaghi et al, Exceptional chemical and thermal stability of zeolitic imidazolate frameworks, PNAS, 2006, 103 (27):10186-10191). The calculated yield of the example was 90%.

Example 3

(25) This example provided a method for preparing a zeolitic imidazolate framework, comprising the following steps:

(26) 6.0365 g of cobalt carbonate and 28.2120 g of 2-methylimidazole were dissolved in 20.0365 g of ethanol and 60.0325 g of DMA, and stirred uniformly;

(27) carbon dioxide was introduced at 27 C. to reach an equilibrium pressure of 0.24 MPa, the pressure was maintained for 50 minutes, and the reaction was terminated;

(28) the reactor was heated to 50 C., and vacuumed to remove carbon dioxide;

(29) after CO.sub.2 was removed, the solid-liquid mixture was separated by filtration, and the solid phase product was placed in a vacuum drying oven, dried and activated to obtain a ZIF-67 crystal, and finally the filtrate was recycled and reused for the next cycle.

(30) The XRD peak shape of the crystal of the example is shown in FIG. 3, which is consistent with the literature report (Qian et al. Hydrothermal synthesis of zeolitic imidazolate framework-67 (ZIF-67) nanocrystals, Materials Letters, 2012, 82:220-223). The yield of ZIF-67 of the example was 80%.

Example 4

(31) This example provided a method for preparing a zeolitic imidazolate framework, comprising the following steps:

(32) 2.7321 g of basic zinc carbonate [ZnCO.sub.3.2Zn(OH).sub.2.H.sub.2O] and 9.5903 g of 2-ethylimidazole were dissolved in 20.0069 g of water and 30.0052 g of DMF, and stirred uniformly;

(33) carbon dioxide was introduced at 30 C. to reach an equilibrium pressure of 1.50 MPa, and the pressure was maintained for 60 minutes, and the reaction was terminated;

(34) the reactor was heated to 50 C., and vacuumed to remove carbon dioxide;

(35) after CO.sub.2 was removed, the solid-liquid mixture was separated by filtration, and the solid phase product was placed in a vacuum drying oven, dried and activated to obtain a ZIF crystal, and finally the filtrate was recycled and reused for the next cycle.

(36) The XRD peak shape of the ZIF crystal of the example is shown in FIG. 4, and is not reported by any literature. The yield of the ZIF crystal of the example was 83%.

Example 5

(37) This example provided a method for preparing a zeolitic imidazolate framework, comprising the following steps:

(38) 1.1243 g of basic zinc carbonate [ZnCO3.2Zn(OH)2.H2O] and 4.7494 g of 2-propylimidazole were dissolved in 50.0036 g of water, and stirred uniformly;

(39) nitrogen dioxide was introduced at 28 C. to reach an equilibrium pressure of 0.14 MPa, and the pressure was maintained for 30 minutes, and the reaction was terminated;

(40) the reactor was heated to 40 C., and vacuumed to remove nitrogen dioxide and carbon dioxide;

(41) after NO.sub.2 and CO.sub.2 was removed, the solid-liquid mixture was separated by filtration, and the solid phase product was placed in a vacuum drying oven, dried and activated to obtain a ZIF crystal, and finally the filtrate was recycled and reused for the next cycle.

(42) The XRD peak shape of the ZIF crystal of the example is shown in FIG. 5, and is not reported by any literature. The yield of the ZIF crystal of the example was 81%.

Example 6

(43) This example provided a method for preparing a zeolitic imidazolate framework, comprising the following steps:

(44) 1.7103 g of basic zinc carbonate [ZnCO.sub.3.2Zn(OH)2.H.sub.2O] and 4.1283 g of imidazole were dissolved in 50.0135 g of water and stirred uniformly;

(45) sulfur dioxide was introduced at 30 C. to reach an equilibrium pressure of 0.6 MPa, and the pressure was maintained for 55 minutes, and the reaction was terminated;

(46) the reactor was heated to 40 C., and vacuumed to remove sulfur dioxide and carbon dioxide;

(47) after SO.sub.2 and CO.sub.2 was removed, the solid-liquid mixture was separated by filtration, and the solid phase product was placed in a vacuum drying oven, dried and activated to obtain a ZIF crystal, and finally the filtrate was recycled and reused for the next cycle.

(48) The XRD peak shape of the ZIF crystal of the example is shown in FIG. 6, and is not reported by any literature. The yield of the ZIF crystal of the example was 74%.

Example 7

(49) This example provided a method for preparing a zeolitic imidazolate framework, comprising the following steps:

(50) 0.3852 g of basic zinc carbonate [ZnCO.sub.3.2Zn(OH)2.H.sub.2O] and 1.9720 g of benzimidazole were dissolved in 50.0132 g of DMF and stirred uniformly;

(51) carbon dioxide was introduced at 40 C. to reach an equilibrium pressure of 0.56 MPa, and the pressure was maintained for 40 minutes, and the reaction was terminated;

(52) the reactor was heated to 40 C., and vacuumed to remove carbon dioxide;

(53) after CO.sub.2 was removed, the solid-liquid mixture was separated by filtration, and the solid phase product was placed in a vacuum drying oven, dried and activated to obtain a ZIF-7 crystal, and finally the filtrate was recycled and reused for the next cycle.

(54) The XRD peak shape of the ZIF-7 crystal of the example is shown in FIG. 7, which is consistent with the literature report (Yaghi et al, Exceptional chemical and thermal stability of zeolitic imidazolate frameworks, PNAS, 2006, 103 (27):10186-10191). The yield of the ZIF-7 of the example was 80%.

Example 8

(55) This example provided a method for preparing a zeolitic imidazolate framework, comprising the following steps:

(56) 0.1842 g of zinc oxide, 0.2623 g of cobalt carbonate and 1.4523 g of 2-methylimidazole were dissolved in 15.0036 g of ethylene glycol and stirred uniformly;

(57) carbon dioxide was introduced at 25 C. to reach an equilibrium pressure of 0.14 MPa, and the pressure was maintained for 30 minutes, and the reaction was terminated;

(58) the reactor was heated to 40 C., and vacuumed to remove carbon dioxide;

(59) after CO.sub.2 was removed, the solid-liquid mixture was separated by filtration, and the solid phase product was placed in a vacuum drying oven, dried and activated to obtain a bimetallic Zn/Co-ZIF crystal, and finally the filtrate was recycled and reused for the next cycle.

(60) The XRD peak shape of the bimetallic Zn/Co-ZIF crystal of the example is shown in FIG. 8 and is consistent with ZIF-8/ZIF-67. The yield of the Zn/Co-ZIF crystal of the example was 86%.

Example 9

(61) This example provided a method for preparing a zeolitic imidazolate framework, comprising the following steps:

(62) 1.0023 g of zinc oxide, 0.6005 g of imidazole, 0.0023 g of 2-methylimidazole, 0.6032 g of 2-ethylimidazole, and 0.60053 g of 2-propylimidazole were dissolved in 50.0036 g of DMA, and stirred uniformly;

(63) carbon dioxide was introduced at 18.5 C. to reach an equilibrium pressure of 0.14 MPa, and the pressure was maintained for 55 minutes, and the reaction was terminated;

(64) the reactor was heated to 40 C., and vacuumed to remove carbon dioxide;

(65) after CO.sub.2 was removed, the solid-liquid mixture was separated by filtration, and the solid phase product was placed in a vacuum drying oven, dried and activated to obtain a composite ZIF crystal, and finally the filtrate was recycled and reused for the next cycle.

(66) The XRD peak shape of the composite ZIF crystal of the example is shown in FIG. 9, and the composite crystal has not been reported in the literature yet. The yield of the composite ZIF of the example was 74%.

Example 10

(67) In this example, ZIF-8 was synthesized from zinc oxide (ZnO) and 2-methylimidazole in an aqueous medium, specifically comprising the following steps:

(68) 3.4202 g of zinc oxide and 8.2501 g of 2-methylimidazole were dissolved in 30.0052 g of water and stirred uniformly;

(69) carbon dioxide was introduced at 25 C. to reach an equilibrium pressure of 0.64 MPa, and the pressure was maintained for 30 minutes, and the reaction was terminated;

(70) the reactor was heated to 50 C., and vacuumed to remove carbon dioxide;

(71) after CO.sub.2 was removed, the solid-liquid mixture was separated by filtration, and the solid phase product was placed in a vacuum drying oven, dried and activated to obtain a ZIF-8 crystal, and finally the filtrate was recycled and reused for the next cycle. After introducing CO.sub.2, it was found by infrared analysis that a new carbonyl absorption peak appeared at 1639 cm.sup.1 after CO.sub.2 absorption in the system (TONG Xiongshi, et al. Removal of CO.sub.2 from natural gas by 2-methylimidazole/ethylene glycol system at room temperature. CIESC Journal, 2016, 67(10): 4240-4245), indicating that CO.sub.2 as a deprotonating agent interacts with the pair of free electron pairs of N on the imidazole ring to form a carbonyl, thereby removing proton hydrogen. The presence of [Zn.(C.sub.4N.sub.2H.sub.5CO.sub.2).H.sub.2O].sup.+ in the system was determined by mass spectrometry analysis (FIG. 10). Therefore, it is speculated that the removed hydrogen ions react with zinc oxide to form water, and zinc ions are combined with the ligand having a carbonyl group to form the intermediate Zn.(C.sub.4N.sub.2H.sub.5CO.sub.2), which is then complexed with solvent water to form [Zn.(C.sub.4N.sub.2H.sub.5CO.sub.2).H.sub.2O], thus continuously consumes zinc oxide. The mechanism is shown as follows:

(72) ##STR00002##

(73) CO.sub.2 is removed from the Zn(C.sub.4N.sub.2H.sub.5CO.sub.2).sup.+ intermediate by appropriate heating and vacuuming, to form Zn(C.sub.4N.sub.2H.sub.5).sup.+, and N atom at 1-position of the resulting 2-methylimidazole ring bonds to Zn ion due to the presence of a lone pair of electrons, and forms ZIF-8 by self-assembly. The mechanism is shown as follows.

(74) ##STR00003##

Example 11

(75) In this example, ZIF-67 was synthesized from cobalt carbonate (CoCO.sub.3) and 2-methylimidazole in an aqueous medium, specifically comprising the following steps:

(76) 3.0335 g of cobalt carbonate and 14.1120 g of 2-methylimidazole were dissolved in 40.0353 g of water and stirred uniformly;

(77) carbon dioxide was introduced at 26 C. to reach an equilibrium pressure of 0.26 MPa, and the pressure was maintained for 30 minutes, and the reaction was terminated;

(78) the reactor was heated to 50 C., and vacuumed to remove carbon dioxide;

(79) after CO.sub.2 was removed, the solid-liquid mixture was separated by filtration, and the solid phase product was placed in a vacuum drying oven, dried and activated to obtain a ZIF-67 crystal, and finally the filtrate was recycled and reused for the next cycle. The mechanism is shown as follows:

(80) ##STR00004##

Example 12

(81) This example provided a method for preparing a zeolitic imidazolate framework, comprising the following steps:

(82) 0.8422 g of basic zinc carbonate [ZnCO.sub.3.2Z(OH).sub.2.H.sub.2O] and 1.2123 g of 2-methylimidazole were dissolved in the recycled filtrate of Example 1, and stirred uniformly;

(83) carbon dioxide was introduced at 25 C. to reach an equilibrium pressure of 0.54 MPa, and the pressure was maintained for 30 minutes, and the reaction was terminated;

(84) then the reactor was heated to 40 C., and vacuumed to remove carbon dioxide;

(85) after CO.sub.2 was removed, the solid-liquid mixture was separated by filtration, and the solid phase product was placed in a vacuum drying oven, dried and activated to obtain a ZIF-8 crystal, and finally the filtrate was recycled and reused for the next cycle.

(86) The XRD peak shape of the ZIF-8 crystal of the example is shown in FIG. 11, which is consistent with the literature report (Yaghi et al, Exceptional chemical and thermal stability of zeolitic imidazolate frameworks, PNAS, 2006, 103 (27):10186-10191). The yield of the ZIF-8 of the example was 91%.