Preparation method and application of crown ether-based multi-metal oxygen cluster catalyst

Abstract

The invention relates to the field of catalyst material preparation technology and application, in particular to a preparation method and application of a crown ether-based polyoxometalate catalyst.The preparation method comprises the steps that strontium salt, phosphomolybdic acid, dicyclohexane-18-crown ether-6 and deionized water are mixed according to a certain proportion, the mixture is put into a clean beaker, stirring is conducted for 20-30 min, and a mixture is obtained; stirring for a period of time at a certain temperature, filtering to obtain a yellow precipitate, drying the precipitate, dissolving the precipitate in DMSO (Dimethylsulfoxide), and standing and slowly volatilizing under an environmental condition; after two weeks, an orange blocky crystal [Sr (DCH18C6) (DMSO) 3] [HPMo12O40] (DCH18C6 = dicyclohexylo-18-crown ether-6) is obtained. The catalyst can realize degradation of mustard gas simulants in pure water. The method disclosed by the invention inherits the idea of green sustainable development, and the catalyst has a clear molecular structure, so that the research on the catalytic reaction mechanism is facilitated.

Description

Technical Field

[0001] The invention belongs to the technical field of catalyst material preparation, and relates to a preparation method and application of a crown ether-based multimetallic oxygen cluster catalyst. Background Art

[0002] Mustard gas is highly toxic, and 2-chloroethyl ethyl sulfide (CEES), which has slightly lower toxicity and contains the same functional groups as mustard gas, is usually selected as a simulant for research. So far, three main mustard gas degradation pathways have been reported: hydrolysis, dehydrogenation, halogenation, and oxidation. However, the reaction rates of hydrolysis and dehydrogenation are low, which limits their practical application. Traditional oxidative decontamination relies on the use of large amounts of corrosive oxidants, such as hypochlorite, which brings negative environmental impacts. Therefore, it is important to find a suitable catalyst to selectively oxidize it to non-toxic sulfoxides rather than over-oxidize it to toxic sulfones.

[0003] Polyoxometalates (POMs) are a class of inorganic metal oxygen clusters composed of transition metals and oxygen atoms. They are widely recognized and studied for their unique topological structure and good electron storage capacity, which makes POMs have broad application prospects in catalysis, biomedicine, energy storage, chemical biology, electronics, materials science and other fields. A large number of POMs have been reported for the degradation of mustard gas (ACS Sustainable Chem. Eng., 2024, 12,4, 1655-1665; Chinese Chem. Lett., 2022, 33, 5, 2625-2629), but the catalysts reported so far still have problems such as low selectivity and poor recyclability. In addition, the reported catalysts usually degrade CEES in organic solvents, but this faces problems such as high toxicity and environmental pollution. Water is the most favored non-classical medium and is popular for its safety, non-flammability, environmental protection and low cost. Therefore, the synthesis of a recyclable mustard gas simulant that can achieve selective oxidation in water is a very important topic at present.

[0004] Crown ethers, as macrocyclic polyether compounds, have been widely used in the field of chemistry, especially in the field of phase transfer catalysis (PTC), due to their unique molecular structure and functional properties. Crown ethers usually have one or more continuous ether oxygen atom rings that can form stable complexes with metal ions. So far, some crown ether-POMs complexes have been explored. However, most of them are alkali metal ions (K + ,Na + ) are selectively encapsulated in crown ethers to form supramolecular cations. Currently, there are no reports on the encapsulation of alkaline earth metal ions in crown ethers and their combination with POMs.

[0005] According to the concept of green synthesis, it is very necessary to design a catalyst for the degradation of mustard gas simulant CEES in water. To this end, we designed and synthesized a highly active, hydrophilic crown ether-based polymetallic oxygen cluster catalyst that can efficiently catalyze the oxidation of CEES to CEESO in water.

[0006] Through searching, no published patent documents related to the present invention application have been found. Summary of the invention

[0007] The invention aims to provide a one-pot method for synthesizing a crown ether-based polymetallic oxygen cluster catalyst in order to solve the problems that the catalyst is difficult to recover, the selectivity is low, the solvent is an organic solvent, the solvent is polluted, the cost is high, and the like in the degradation of a mustard gas simulant CEES. The method has excellent catalytic activity (conversion rate is 100%, selectivity is 96%) under the condition of using pure water as solvent.

[0008] The scheme of the present invention is that a crown ether-based multimetallic oxygen cluster catalyst realizes the degradation of mustard gas simulant 2-chloroethyl ethyl sulfide (CEES) in pure water.

[0009] As mentioned above [Sr(DCH 18 C6)(DMSO)3][HPMo 12 O 40 ] A method for preparing a crown ether-based multimetallic oxygen cluster catalyst, comprising the following steps:

[0010] In a clean beaker, add strontium chloride hexahydrate and dicyclohexane-18-crown ether-6 in turn and mix with water, stir, and then add H3PMo 12 O 40 The aqueous solution was stirred at a certain temperature for 2 h, filtered, the precipitate was dried and dissolved in DMSO to form a saturated solution, and the solution was allowed to stand under ambient conditions. After two weeks, block crystals were generated.

[0011] The preferred method is to add SrCl2·6H2O (0.3 mmol) and dicyclohexane-18-crown-6 (0.3 mmol) in a clean beaker and mix with H2O (10 mL), stir, and then add H3PMo 12 O 40 (0.18 mmol) in aqueous solution (10 mL) at 25 o C for 2 h, filtered, the precipitate was dried and dissolved in DMSO to form a saturated solution, and the solution was allowed to stand under ambient conditions. After two weeks, orange-yellow block crystals were generated with a yield of about 24-50%.

[0012] The product was characterized by single crystal X-ray diffraction and powder X-ray diffraction to obtain accurate information about the crystal structure. The specific results are as follows:

[0013] The molecular formula of the crystal is [Sr(DCH 18 C6)(DMSO)3][HPMo 12 O 40 ], crystallized in the triclinic P-1 space group, with the asymmetric unit consisting of a [PMo 12 O 40 ] 3− anion and a [Sr(DCH 18 C6)(DMSO)3] 2+ Cation composition. Among the cations, Sr 2+ The ion is completely concentrated in the cavity of dicyclohexaned-18-crown-6-ether, coordinated with 6 oxygen atoms from the ether and with the oxygen in three molecules of DMSO.

[0014] The present invention has the following beneficial effects:

[0015] 1. The preparation method is simple, and the catalysts have a clear molecular structure, which is conducive to studying the mechanism of catalytic reactions.

[0016] 2. The catalyst can achieve 100% degradation of mustard gas simulant in pure water with high selectivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 For the compound [Sr(DCH 18 C6)(DMSO)3][HPMo 12 O 40 ] schematic diagram of the crystal structure;

[0018] Figure 2 For the compound [Sr(DCH 18 C6)(DMSO)3][HPMo 12 O 40 ]’s PXRD characterization diagram. DETAILED DESCRIPTION

[0019] The present invention is described in detail below in conjunction with the examples, but the scope of protection is not limited thereto. The experimental methods in the following examples are conventional methods unless otherwise specified, and the materials, reagents, etc. used in the following examples are all commercially available unless otherwise specified.

[0020] Embodiment 1:

[0021] Compound [Sr(DCH 18 C6)(DMSO)3][HPMo 12 O 40 Preparation of

[0022] In a clean beaker, SrCl2·6H2O (0.3 mmol) and dicyclohexane-18-crown-6 (0.3 mmol) were added in sequence and mixed with H2O (10 mL). After stirring, H3PMo was added. 12 O 40 (0.18 mmol) in aqueous solution (10 mL) at 15 o C for 2 h, filtered, the precipitate was dried and dissolved in DMSO to form a saturated solution, and the solution was allowed to stand under ambient conditions. After two weeks, orange-yellow block crystals were generated. The yield was 35%.

[0023] Embodiment 2:

[0024] Compound [Sr(DCH 18 C6)(DMSO)3][HPMo 12 O 40 Preparation of

[0025] In a clean beaker, SrCl2·6H2O (0.3 mmol) and dicyclohexane-18-crown-6 (0.3 mmol) were added in sequence and mixed with H2O (10 mL). After stirring, H3PMo was added. 12 O 40 (0.18 mmol) in aqueous solution (10 mL) at 25 o C for 2 h, filtered, the precipitate was dried and dissolved in DMSO to form a saturated solution, and the solution was allowed to stand under ambient conditions. After two weeks, orange-yellow block crystals were generated. The yield was 50%.

[0026] Embodiment 3:

[0027] Compound [Sr(DCH 18 C6)(DMSO)3][HPMo 12 O 40 Preparation of

[0028] In a clean beaker, SrCl2·6H2O (0.3 mmol) and dicyclohexane-18-crown-6 (0.3 mmol) were added in sequence and mixed with H2O (10 mL). After stirring, H3PMo was added. 12 O 40 (0.18 mmol) in aqueous solution (10 mL) at 35 o C for 2 h, filtered, the precipitate was dried and dissolved in DMSO to form a saturated solution, and the solution was allowed to stand under ambient conditions. After two weeks, orange-yellow block crystals were generated. The yield was 37%.

[0029] Embodiment 4:

[0030] Compound [Sr(DCH 18 C6)(DMSO)3][HPMo 12 O 40 Preparation of

[0031] In a clean beaker, SrCl2·6H2O (0.25 mmol) and dicyclohexane-18-crown-6 (0.3 mmol) were added in sequence and mixed with H2O (10 mL). After stirring, H3PMo was added. 12 O 40 (0.3 mmol) in aqueous solution (10 mL) at 25 o C for 2 h, filtered, the precipitate was dried and dissolved in DMSO to form a saturated solution, and the solution was allowed to stand under ambient conditions. After two weeks, orange-yellow block crystals were generated. The yield was 34%.

[0032] Embodiment 5:

[0033] Compound [Sr(DCH 18 C6)(DMSO)3][HPMo 12 O 40 Preparation of

[0034] In a clean beaker, SrCl2·6H2O (0.2 mmol) and dicyclohexane-18-crown-6 (0.3 mmol) were added in sequence and mixed with H2O (10 mL). After stirring, H3PMo was added. 12 O 40 (0.24 mmol) in aqueous solution (10 mL) at 25 o C for 2 h, filtered, the precipitate was dried and dissolved in DMSO to form a saturated solution, and the solution was allowed to stand under ambient conditions. After two weeks, orange-yellow block crystals were generated. The yield was 40%.

[0035] Embodiment 6:

[0036] Compound [Sr(DCH 18 C6)(DMSO)3][HPMo 12 O 40 Preparation of

[0037] In a clean beaker, SrCl2·6H2O (0.2 mmol) and dicyclohexane-18-crown-6 (0.2 mmol) were added in sequence and mixed with H2O (10 mL). After stirring, H3PMo was added. 12 O 40 (0.12 mmol) in aqueous solution (10 mL) at 25 oC for 2 h, filtered, the precipitate was dried and dissolved in DMSO to form a saturated solution, and the solution was allowed to stand under ambient conditions. After two weeks, orange-yellow block crystals were generated. The yield was 24%.

[0038] Embodiment 7:

[0039] Degradation of Mustard Gas Simulant 2-Chloroethyl Ethyl Sulfide (CEES)

[0040] The catalyst (1 mmol%), CEES (0.2 mmol), and H2O2 (0.24 mmol) were mixed with H2O (2 mL) in a clean Shrek tube and heated at 40 o C for 1 h. After the reaction is complete, 20.0 μL (0.20 mmol) of chlorobenzene is added to the cooled solution and shaken. The supernatant is extracted with a syringe and filtered through a syringe filter. 1.5 mL of the solution is added to a gas chromatograph vial. The conversion rate and selectivity of the CEES catalytic oxidation reaction are determined using a GC-7890B gas chromatograph. The conversion rate is 100% and the selectivity is 96%.

[0041] Table 1. Compounds [Sr(DCH 18 C6)(DMSO)3][HPMo 12 O 40 ] crystallographic data

[0042]

[0043] As shown below, the catalyst [Sr(DCH 18 C6)(DMSO)3][HPMo 12 O 40 ] The degradation results of mustard gas simulant CEES are as follows:

[0044]

[0045] The above results show that [Sr(DCH 18 C6)(DMSO)3][HPMo 12 O 40 The catalyst showed high catalytic activity in the degradation of mustard gas simulant CEES in pure water. Under the condition of hydrogen peroxide as oxidant, it could effectively catalyze the conversion of CEES into non-toxic sulfoxide product (CEESO) instead of toxic sulfone (CEESO2). o Under C conditions, the conversion rate can reach 100% within 1 hour, and the selectivity is 96%.

[0046] Of course, the above embodiments of the present invention are only examples for illustrating the present invention, and are not intended to limit the specific implementation methods of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above examples. It is impossible to give detailed examples of all implementation methods here. All obvious changes or modifications derived from the technical solution of the present invention are still within the scope of protection of the present invention.

Claims

1. A method for preparing a crown ether-based polymetallic oxygen cluster catalyst, characterized in that: The steps are as follows: add strontium chloride hexahydrate and dicyclohexane-18-crown ether-6 in a container in sequence and mix with water, stir, and then add H3PMo 12 O 40 The aqueous solution was stirred at a certain temperature for 2 h, filtered, the precipitate was dried and dissolved in DMSO, and the solution was allowed to stand under ambient conditions. After two weeks, good block crystals were generated.

2. The method for preparing the crown ether-based polymetallic oxygen cluster catalyst according to claim 1, characterized in that: Strontium chloride hexahydrate: H3PMo 12 O 40 The molar ratio of dicyclohexane-18-crown ether-6 is 0.20-0.4: 0.12-0.24: 0.20-0.4, and the mixture is stirred at 15 o C~35 o C.

3. Use of the catalyst obtained by the preparation method as described in any one of claims 1-2 in pure water to achieve the degradation of mustard gas simulant 2-chloroethyl ethyl sulfide (CEES).

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