A standberg-type polyoxometalate-based organic-inorganic compound for catalytic oxidative desulfurization, a synthesis method and application thereof

Abstract

The application discloses a Standberg type polyoxometalate-based organic-inorganic compound for catalytic oxidative desulfurization, a synthesis method and application, and has a molecular formula of [Zn(H2datrz)2(P2Mo5O 23 )(H2O)2]·11H2O.The synthesis method comprises the following steps: in step one, zinc acetate, 3,5-diamino-1,2,4-triazole, sodium molybdate and deionized water are mixed to be homogeneous; the molar ratio of zinc acetate to deionized water is 1:173, the molar ratio of 3,5-diamino-1,2,4-triazole to sodium molybdate is 1:1, and the molar ratio of 3,5-diamino-1,2,4-triazole to zinc acetate is 4:3; in step two, the pH value is adjusted to 2.5-3, and after stirring, heating and hot filtration are carried out; and in step three, the filtrate is placed at room temperature for one week to obtain the product.The application has the characteristics of low cost, high yield and high catalytic efficiency.

Description

Technical Field

[0001] This invention relates to the field of organic catalysis and synthesis methods, and more specifically, to a Standberg-type polyoxometalate-based organic-inorganic compound for catalytic oxidative desulfurization and its synthesis method. Background Technology

[0002] Research on the oxidation reaction of sulfides has always attracted much attention. On the one hand, the oxidation products of sulfides, sulfoxides and sulfones, are widely used in fine chemicals such as pharmaceuticals and pesticides, while sulfones and sulfoxides are important synthetic intermediates in organic synthesis reactions, showing broad application prospects in the synthesis of functional materials and molecular recombination. On the other hand, sulfides, as a major source of sulfur, are widely present in fuels such as diesel and gasoline. During high-temperature combustion, sulfides are converted into SO₂. x This leads to the formation of acid rain and acid fog, which harm the environment and human health.

[0003] With the increasing global awareness of environmental protection, the development of efficient fuel desulfurization technology has become a research hotspot. Oxidative desulfurization technology has received widespread attention due to its advantages such as low cost, high desulfurization efficiency, and good product selectivity. However, its shortcomings lie in the weak oxidation capacity of hydrogen peroxide (H2O2), molecular oxygen, and tert-butyl hydrogen peroxide, especially at low temperatures where it is difficult to achieve good oxidation results. As a result, the reaction system requires the assistance of a catalyst to complete the oxidation reaction. Therefore, in the process of using H2O2 as an oxidant to achieve green oxidation, a more efficient catalytic system needs to be established.

[0004] Polyoxometalates (POMs), as inorganic metal oxide clusters with well-defined structures and remarkable physicochemical properties, are widely used in catalysis, optics, magnetism, electrochemistry, medicine and other fields. In particular, their excellent thermal stability, compatibility with various oxidants and unique redox behavior make them ideal catalysts for sulfide conversion. Summary of the Invention

[0005] The purpose of this invention is to design and develop a Standberg-type polyoxometalate-based organic-inorganic compound for catalytic oxidative desulfurization, which has high crystallinity and good structural stability.

[0006] This invention also designed and developed a method for synthesizing Standberg-type polyoxometalate-based organic-inorganic compounds for catalytic oxidative desulfurization. The method involves adjusting the ratio of zinc acetate, 3,5-diamino-1,2,4-triazole, and sodium molybdate, and can be synthesized at room temperature with a high yield.

[0007] The application also designs and develops an application of a Standberg type polyoxometalate-based organic-inorganic compound for catalytic oxidative desulfurization, which has stronger catalytic performance and can be reused.

[0008] The technical scheme provided by the application is:

[0009] A Standberg type polyoxometalate-based organic-inorganic compound for catalytic oxidative desulfurization, the molecular formula of the Standberg type polyoxometalate-based organic-inorganic compound is [Zn(H2datrz)2(P2Mo5O 23 )(H2O)2]·11H2O;

[0010] Hdatrz is 3,5-diamino-1,2,4-triazole, H2datrz is a protonated H2datrz cation because Hdatrz is protonated in the Standberg type polyoxometalate-based organic-inorganic compound.

[0011] A synthesis method of a Standberg type polyoxometalate-based organic-inorganic compound for catalytic oxidative desulfurization, comprising the following steps:

[0012] Step one, zinc acetate, 3,5-diamino-1,2,4-triazole, sodium molybdate and deionized water are mixed to be homogeneous;

[0013] The molar ratio of the zinc acetate to the deionized water is 1:173, the molar ratio of the 3,5-diamino-1,2,4-triazole to the sodium molybdate is 1:1, and the molar ratio of the 3,5-diamino-1,2,4-triazole to the zinc acetate is 4:3.

[0014] Step two, the pH value of the mixed solution is adjusted to 2.5, and after stirring, it is heated to 95 DEG C and lasts for 2 hours, and then hot filtration is performed;

[0015] Step three, the filtrate is placed at room temperature for one week to obtain the Standberg type polyoxometalate-based organic-inorganic compound.

[0016] Preferably, the zinc acetate is (CH3COO)2Zn·2H2O, and the sodium molybdate is Na2MoO4·2H2O.

[0017] Preferably, in step two, the pH value is adjusted by 85% H3PO4.

[0018] Preferably, the stirring time in step two is 30 minutes.

[0019] Preferably, the heating rate in step two is 15 DEG C / h.

[0020] Preferably, the heating process in the step two needs to keep sealed.

[0021] Preferably, the Standberg-type polyoxometalate-based organic-inorganic compound is yellow block crystal.

[0022] Preferably, further comprising:

[0023] The obtained yellow block crystal is washed with deionized water for 2-4 times.

[0024] The application of a Standberg-type polyoxometalate-based organic-inorganic compound for catalytic oxidative desulfurization, the synthesis method of the Standberg-type polyoxometalate-based organic-inorganic compound for catalytic oxidative desulfurization, and the application of the Standberg-type polyoxometalate-based organic-inorganic compound in selective oxidation catalysis of sulfides.

[0025] The beneficial effects of the present application are:

[0026] (1) The Standberg-type polyoxometalate-based organic-inorganic compound for catalytic oxidative desulfurization is designed and developed by the present application, which is composed of protonated H2datrz cation, Standberg-type [P2Mo5O 23 ] 6- anion and central zinc metal ion, forming one-dimensional (1D) chain structure, and these 1D chain structures are further assembled into three-dimensional (3D) supramolecular network structure through multiple hydrogen bond interactions, having high crystallinity and good structural stability.

[0027] (2) The synthesis method of the Standberg-type polyoxometalate-based organic-inorganic compound for catalytic oxidative desulfurization is simple, fast, short synthesis period, high synthesis yield, and low synthesis cost.

[0028] (3) The application of the Standberg-type polyoxometalate-based organic-inorganic compound for catalytic oxidative desulfurization is easy to separate from the reaction medium, does not pollute the reaction product, has stronger catalytic performance, can be reused in the subsequent cycle reaction, and still can maintain high catalytic efficiency, and due to the unique structural characteristics of the compound, the compound has the potential to become a new type of catalyst for selective oxidation of sulfides, opening up a new direction for related research. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 The coordination environment diagram of the compound is shown in the present application.

[0030] Figure 2 The structure of the compound of the present application is [P2Mo5O 23 ] 6- The structure diagram.

[0031] Figure 3 The 1D chain structure diagram of the compound of the present application.

[0032] Figure 4 The infrared spectrum of the Standberg-type polyoxometalate-based organic-inorganic compound for catalyzing oxidative desulfurization of the present application.

[0033] Figure 5 The X-ray powder diffraction pattern of the Standberg-type polyoxometalate-based organic-inorganic compound for catalyzing oxidative desulfurization of the present application.

[0034] Figure 6 The recovered infrared spectrum of the product of the embodiment of the present application after the catalytic oxidation of p-methoxythioanisole is repeated three times.

[0035] Figure 7 The X-ray powder diffraction pattern of the product of the embodiment of the present application after the catalytic oxidation of p-methoxythioanisole is repeated three times. DETAILED DESCRIPTION

[0036] The present application will be further described in detail below, so that those skilled in the art can implement the present application according to the description.

[0037] As Figures 1-3 shown, the present application provides a Standberg-type polyoxometalate-based organic-inorganic compound for catalyzing oxidative desulfurization, and the molecular formula is [Zn(H2datrz)2(P2Mo5O 23 )(H2O)2]·11H2O.

[0038] In the formula, Hdatrz is 3,5-diamino-1,2,4-triazole, and the structural formula is

[0039]

[0040] Since Hdatrz is protonated in the Standberg-type polyoxometalate-based organic-inorganic compound, H2datrz is a protonated H2datrz cation.

[0041] The present application provides a Standberg-type polyoxometalate-based organic-inorganic compound for catalyzing oxidative desulfurization, and the compound comprises a protonated H2datrz cation, a Standberg-type [P2Mo5O 23 ]6- The anions and the central zinc metal ion group form one-dimensional (1D) chain structures which are further assembled into three-dimensional (3D) supramolecular network structures through multiple hydrogen bond interactions, having high crystallinity and good structural stability.

[0042] The application further provides a synthesis method of a Standberg type polyoxometalate-based organic-inorganic compound for catalytic oxidative desulfurization, comprising the following steps:

[0043] Step one, mixing zinc acetate, 3,5-diamino-1,2,4-triazole, sodium molybdate and deionized water until homogeneous;

[0044] The zinc acetate is (CH3COO)2Zn·2H2O, the sodium molybdate is Na2MoO4·2H2O, the molar ratio of the zinc acetate to the deionized water is 1:173, the molar ratio of the 3,5-diamino-1,2,4-triazole to the sodium molybdate is 1:1, and the molar ratio of the 3,5-diamino-1,2,4-triazole to the zinc acetate is 4:3.

[0045] Step two, adjusting the pH value of the mixed solution to 2.5, stirring, heating to 95℃ and maintaining for 2h, and hot filtering;

[0046] In the embodiment, the pH value is adjusted by 85% H3PO4, the stirring time is 30 minutes, and the temperature rising rate is 15℃ / h;

[0047] In the embodiment, the heating process needs to seal the beaker;

[0048] Step three, placing the filtrate at room temperature for one week to obtain the Standberg type polyoxometalate-based organic-inorganic compound;

[0049] The filtrate obtained after hot filtering needs to be kept undisturbed at room temperature for one week;

[0050] The Standberg type polyoxometalate-based organic-inorganic compound is a yellow block crystal, and after obtaining the yellow block crystal, the yellow block crystal needs to be washed with deionized water for 2-4 times.

[0051] Embodiment

[0052] 2 mmol Na2MoO4·2H2O, 1.5 mmol (CH3COO)2Zn·2H2O and 2 mmol Hdatrz were added to a beaker containing 20 mL of deionized water and stirred until homogeneous. Then, 85% H3PO4 was added dropwise to adjust the pH to 2.5. After stirring for 30 min, the temperature was increased to 95 °C at a rate of 15 °C / h and maintained for 2 hours. After hot filtration, the filtrate was kept undisturbed at room temperature for one week, and finally, yellow blocky crystals with a yield of about 40% (based on metallic Mo) were obtained.

[0053] like Figure 1 The diagram shown is a coordination environment diagram of the compound, where, as... Figure 2 As shown, [P2Mo5O 23 ] 6- Anions can be viewed as consisting of two parts: a ring structure assembled from five MoO6 octahedra sharing a corner and six sides, and two PO4 tetrahedra capped on either side of the ring, as shown below. Figure 3 As shown, adjacent [P2Mo5O] 23 ] 6- The anion further forms a 1D chain structure through zinc ion bridging, wherein the zinc ion exhibits an octahedral coordination configuration, and is associated with two nitrogen atoms on the ligand and [P2Mo5O], respectively. 23 ] 6- The two oxygen atoms on the anion are connected to two coordinated water molecules.

[0054] In another embodiment, changing the proportion of the synthetic raw materials will result in an impure compound or an inability to synthesize it. That is, the compound is impure when the proportion of the synthetic raw materials is close to that described in this invention, and the inability to synthesize it will result when the proportion of the synthetic raw materials changes too much.

[0055] The compounds obtained in the examples were characterized as follows:

[0056] 1. Infrared spectroscopy characterization of phase composition:

[0057] The infrared spectra of compound materials were tested using an FT-IR spectrometer, such as... Figure 4 As shown, the compound at 3332 and 3142 cm⁻¹ -1 The absorption peaks at these locations are attributed to the OH stretching vibration of water molecules and the N-stretching vibration of the exocyclic amino group in the Hdatrz ligand, respectively. In the low wavenumber region, the Strandberg type [P2Mo5O]... 23 ] 6- The absorption peak is located at 1039 cm⁻¹ -1 and 1009cm -1 Furthermore, the absorption peak of Mo-O appears at 959 cm⁻¹. -1 and 890cm -1and the Mo-O-Mo absorption peak is distributed at 557cm -1 ~793cm -1 .

[0058] 2. Powder diffraction characterization phase purity:

[0059] The powder diffraction data is collected on a Rigaku Ultima IV X-ray diffractometer, the operating current is 40mA, the voltage is 40kV, a molybdenum target X-ray is used, fixed scanning, the receiving slit width is 0.1mm, the density data collection scanning range is 5° to 50°, the scanning speed is 5° / s, the span is 0.02° / time, and the single crystal structure powder diffraction spectrum simulation conversion uses Mercury1.4.1.

[0060] As shown in Figure 5 , the powder X-ray diffraction spectrum of the compound is basically consistent with the fitting spectrum, indicating that the Standberg type polyoxometalate-based organic-inorganic compound obtained in the embodiment has high crystallinity and is a pure phase.

[0061] 3. Crystal structure determination:

[0062] Suitable size single crystals are selected by a microscope, and the diffraction data is collected at room temperature by using a Bruker SMART APEX II diffractometer (graphite monochromator, Mo Kα (λ=0.071073nm)), the scanning mode is ω-θ diffraction data, the absorption correction is performed by using the SADABS program, the data reduction and structure analysis are respectively completed by using the direct method and the SHELX program, and the optimization is performed by using the ShelXL program of least squares minimization, Figures 1-3 The crystal structure of the compound synthesized in the embodiment is shown, and the detailed crystallographic diffraction point data is shown in Table 1.

[0063] Table 1 Detailed crystallographic diffraction point data of the compound in the embodiment

[0064]

[0065]

[0066] The synthesis method of the Standberg type polyoxometalate-based organic-inorganic compound for catalytic oxidation desulfurization designed and developed by the application is simple, fast, has a short synthesis period, a high synthesis yield, and a low synthesis cost.

[0067] The application also provides a use of a Standberg-type polyoxometalate-based organic-inorganic compound for catalytic oxidative desulfurization, which can be used as a catalyst for selective oxidation of sulfides, and the catalyst is not only suitable for selective oxidation of thioanisole, but also can effectively catalyze selective oxidation of 4-bromothioanisole, 4-chlorothioanisole, diphenyl disulfide and 2-chloroethyl ethyl sulfide and the like, and exhibits excellent catalytic performance.

[0068] The application of the compound obtained in the examples to selective catalytic oxidation of sulfides (main product: sulfoxide) is characterized in that the molar ratio of the catalyst to the sulfide is 0.021:1:

[0069] 1. Catalytic oxidation of thioanisole:

[0070] The compound obtained in the examples is used as a catalyst, 0.4 mmol of thioanisole, 10 μmol of the polyoxometalate-based organic-inorganic compound, 0.42 mmol of hydrogen peroxide (oxidizing agent) and 5 mL of methanol solvent are put into a brown glass bottle, the reaction temperature is controlled at room temperature 25℃, and the reaction is stopped after stirring for 20 min.

[0071] 2. Catalytic oxidation of 4-chlorothioanisole:

[0072] The compound obtained in the examples is used as a catalyst, 0.4 mmol of 4-chlorothioanisole, 10 μmol of the polyoxometalate-based organic-inorganic compound, 0.42 mmol of hydrogen peroxide and 5 mL of methanol solvent are put into a brown glass bottle, the reaction temperature is controlled at room temperature 25℃, and the reaction is stopped after stirring for 20 min.

[0073] 3. Catalytic oxidation of 4-bromothioanisole:

[0074] The compound obtained in the examples is used as a catalyst, 0.4 mmol of 4-bromothioanisole, 10 μmol of the polyoxometalate-based organic-inorganic compound, 0.42 mmol of hydrogen peroxide and 5 mL of methanol solvent are put into a brown glass bottle, the reaction temperature is controlled at room temperature 25℃, and the reaction is stopped after stirring for 20 min.

[0075] 4. Catalytic oxidation of diphenyl disulfide:

[0076] The compound obtained in the examples is used as a catalyst, 0.4 mmol of diphenyl disulfide, 10 μmol of the polyoxometalate-based organic-inorganic compound, 0.42 mmol of hydrogen peroxide and 5 mL of methanol solvent are put into a brown glass bottle, the reaction temperature is controlled at room temperature 25℃, and the reaction is stopped after stirring for 20 min.

[0077] 5. Catalytic oxidation of dibenzyl sulfide:

[0078] The compound obtained in the example was used as a catalyst, 0.4 mmol of dibenzyl sulfide, 10 μmol of the polyacid-based organic-inorganic compound, 0.42 mmol of hydrogen peroxide, and 5 mL of methanol solvent were put into a brown glass bottle, the reaction temperature was controlled at room temperature 25°C, and after stirring for 20 min, the reaction was stopped.

[0079] 6. Catalytic oxidation of diethyl sulfide:

[0080] The compound obtained in the example was used as a catalyst, 0.4 mmol of dibenzyl sulfide, 10 μmol of the polyacid-based organic-inorganic compound, 0.42 mmol of hydrogen peroxide, and 5 mL of methanol solvent were put into a brown glass bottle, the reaction temperature was controlled at room temperature 25°C, and after stirring for 20 min, the reaction was stopped.

[0081] The sample was prepared for GC-MS detection, naphthalene was used as an internal standard, the conversion rate and selectivity of the catalytic oxidation of sulfide compounds were calculated from the results of GC-MS, and the conversion rate of the catalytic oxidation of sulfide compounds was represented as:

[0082]

[0083] The selectivity of the catalytic oxidation of sulfide compounds was represented as:

[0084]

[0085] The reaction formula of the catalytic oxidation of sulfide compounds was represented as:

[0086]

[0087] In the catalytic oxidation of anisyl sulfide using the compound obtained in the example, the GC-MS results showed that the conversion rate of the oxidation of the reaction substrate into the corresponding sulfoxide was 99%, and the selectivity was 96%; in the catalytic oxidation of 4-chloroanisyl sulfide using the compound obtained in the example, the GC-MS results showed that the conversion rate of the oxidation of the reaction substrate into the corresponding sulfoxide was 99%, and the selectivity was 91%; in the catalytic oxidation of 4-bromoanisyl sulfide using the compound obtained in the example, the GC-MS results showed that the conversion rate of the oxidation of the reaction substrate into the corresponding sulfoxide was 98%, and the selectivity was 90%; in the catalytic oxidation of diphenyl disulfide using the compound obtained in the example, the GC-MS results showed that the conversion rate of the oxidation of the reaction substrate into the corresponding sulfoxide was 97%, and the selectivity was 92%; in the catalytic oxidation of dibenzyl sulfide using the compound obtained in the example, the GC-MS results showed that the conversion rate of the oxidation of the reaction substrate into the corresponding sulfoxide was 98%, and the selectivity was 93%; in the catalytic oxidation of diethyl sulfide using the compound obtained in the example, the GC-MS results showed that the conversion rate of the oxidation of the reaction substrate into the corresponding sulfoxide was 99%, and the selectivity was 93%.

[0088] The compound obtained in the example is recycled after the catalytic reaction of thioanisole is finished. The recycling method is as follows: after the reaction is finished, the obtained solution is filtered to filter out the polyacid-based organic-inorganic compound, which is recycled after treatment. The recycled compound is used again in the catalytic oxidation reaction of thioanisole. After the first recycling, the conversion rate of thioanisole is 96% and the selectivity is 94% according to the GC-MS analysis. After the catalyst is recycled and used for three times, the conversion rate of thioanisole is greater than 95% and the selectivity is 94% according to the GC-MS analysis. It can be seen that the catalytic effect does not weaken obviously. The sample recycled after being used for three times is characterized by infrared and powder diffraction, which is consistent with the original infrared spectrum and powder diffraction spectrum, indicating that the polyacid-based organic-inorganic compound has good stability in the catalytic process. Figures 6-7

[0089] The application of the Standberg-type polyoxometalate-based organic-inorganic compound for catalytic oxidation desulfurization designed and developed by the application can always be carried out at room temperature 25℃ and has good catalytic capacity, fast catalytic speed, high conversion rate and good selectivity.

[0090] Although the embodiments of the application have been disclosed as above, they are not limited to the application listed in the specification and the embodiments, and can be fully applied to various fields suitable for the application. Those skilled in the art can easily realize other modifications, and therefore the application is not limited to specific details and the examples shown and described herein.​

Claims

1. A Standberg type polyoxometalate based organic-inorganic compound for catalytic oxidative desulfurization, characterized in that, The molecular formula of the Standberg-type polyoxometalate-based organic-inorganic compound is [Zn(H2datrz)2(P2Mo5O 23 )(H2O)2]·11H2O; Hdatrz is 3,5-diamino-1,2,4-triazole, and H2datrz is a protonated H2datrz cation because Hdatrz is protonated in the Standberg-type polyoxometalate-based organic-inorganic compound.

2. A process for the synthesis of Standberg type polyoxometalate based organic-inorganic compounds for catalytic oxidative desulfurization characterized by, The method comprises the following steps: Step one, mixing zinc acetate, 3,5-diamino-1,2,4-triazole, sodium molybdate and deionized water to be homogeneous; The molar ratio of zinc acetate to deionized water is 1:173, the molar ratio of 3,5-diamino-1,2,4-triazole to sodium molybdate is 1:1, and the molar ratio of 3,5-diamino-1,2,4-triazole to zinc acetate is 4:

3. Step two, adjusting the pH value of the mixed solution to 2.5, stirring, heating to 95℃ and maintaining for 2h, and hot filtering; Step three, standing the filtrate at room temperature for one week to obtain the Standberg-type polyoxometalate-based organic-inorganic compound.

3. The method for synthesizing Standberg-type polyoxometalate-based organic-inorganic compounds for catalytic oxidative desulfurization as described in claim 2, characterized in that, The zinc acetate is (CH3COO)2Zn·2H2O, and the sodium molybdate is Na2MoO4·2H2O.

4. The method for synthesizing Standberg-type polyoxometalate-based organic-inorganic compounds for catalytic oxidative desulfurization as described in claim 3, characterized in that, The pH value is adjusted by 85% H3PO4 in the step two.

5. The method for synthesizing Standberg-type polyoxometalate-based organic-inorganic compounds for catalytic oxidative desulfurization as described in claim 4, characterized in that, The stirring time in the step two is 30 minutes.

6. The method for synthesizing Standberg-type polyoxometalate-based organic-inorganic compounds for catalytic oxidative desulfurization as described in claim 5, characterized in that, The heating rate in the step two is 15℃ / h.

7. The method for synthesizing Standberg-type polyoxometalate-based organic-inorganic compounds for catalytic oxidative desulfurization as described in claim 6, characterized in that, The heating process needs to be sealed in the step two.

8. The method for synthesizing Standberg-type polyoxometalate-based organic-inorganic compounds for catalytic oxidative desulfurization as described in claim 7, characterized in that, The Standberg-type polyoxometalate-based organic-inorganic compound is a yellow block crystal.

9. The method for synthesizing Standberg-type polyoxometalate-based organic-inorganic compounds for catalytic oxidative desulfurization as described in claim 8, characterized in that, Further comprising: The obtained yellow block crystal is washed with deionized water for 2-4 times.

10. Use of a Standberg-type polyoxometalate-based organic-inorganic compound for catalytic oxidative desulfurization, wherein the Standberg-type polyoxometalate-based organic-inorganic compound is synthesized using the synthesis method for a Standberg-type polyoxometalate-based organic-inorganic compound for catalytic oxidative desulfurization according to any one of claims 2 to 9, characterized in that, The application of the Standberg-type polyoxometalate-based organic-inorganic compound in the catalysis of selective oxidation of sulfides.

Images