A polymetallic tungstate crystal material with three-dimensional structure and preparation method thereof

Abstract

The present invention discloses a polymetallic tungstate crystal material with a three-dimensional structure and a preparation method thereof. The chemical formula of the polymetallic tungstate crystal is [Na6(H2O)8Mn2(H2O)6[H2W 12 O 42 ]·4H2O, belongs to the monoclinic system, the space group is P2(1) / n, the unit cell parameters are #imgabs0#β=109.4080(10)°, #imgabs1#Z=2. The metal tungstate crystal is prepared by hydrothermal synthesis, and tungstic acid, sodium chloride, sodium tetraborate, manganese chloride, lanthanum oxide and water are placed in a closed system for synthesis. The crystal material can play a catalytic role in the preparation of glutaraldehyde by oxidizing cyclopentene with hydrogen peroxide, and the product yield can reach more than 60%, showing a high catalytic activity.

Description

Technical Field

[0001] The invention belongs to the field of polymetallic oxoates and crystal materials, and specifically relates to a polymetallic tungstate crystal material with a three-dimensional structure and a preparation method thereof. Background Art

[0002] Early transition metal atoms (vanadium, niobium, tantalum, molybdenum and tungsten) can form polymetallic-oxygen clusters in their high oxidation states. Due to their unique molecular and electronic structures, these substances often have excellent electrical conductivity, magnetism, redox, catalysis and optical nonlinearity, and are widely used in analysis, clinical diagnosis, catalysis (including photocatalysis), biochemistry, medicine and materials science.

[0003] With the development of advanced materials, the assembly of polyoxometalates with specific composition and function has attracted more and more attention. However, since polyoxometalates are very sensitive to pH, temperature and reaction time, it is still difficult to synthesize polyoxometalates with novel structures. In the field of polyoxometalate materials, people have been studying one of the important families - polymetallic tungstate materials. Some materials with polymeric extended structures have been reported. These polymeric extended structures are usually connected by organic ligands or organometallic groups, while pure inorganic extended structures formed by simple inorganic ion connection, especially crystalline materials with three-dimensional extended structures, are rarely reported. Summary of the invention

[0004] The technical problem to be solved by the present invention is to overcome the defects of the prior art and propose a polymetallic tungstate crystal material with a three-dimensional structure.

[0005] In order to solve the technical problem of the present invention, the technical solution adopted is:

[0006] A polymetallic tungstate crystal material with a three-dimensional structure, the chemical formula of the polymetallic tungstate crystal is [Na6(H2O)8Mn2(H2O)6[H2W 12 O 42 ]·4H2O, the structural formula is as follows:

[0007]

[0008] The polymetallic tungstate crystal belongs to the monoclinic system, the space group is P2(1) / n, and the unit cell parameters are β=109.4080(10) o , Z=2,D c =3.666g / cm 3 .

[0009] The present invention also provides a method for preparing the above-mentioned polymetallic tungstate crystalline material with a three-dimensional structure, specifically: the above-mentioned polymetallic tungstate crystalline material is prepared by a hydrothermal synthesis method, 0.1 to 0.15 parts by weight of tungstic acid, 0.05 to 0.08 parts by weight of sodium chloride, 0.02 to 0.05 parts by weight of sodium tetraborate, 0.07 to 0.12 parts by weight of manganese chloride, 0.02 to 0.04 parts by weight of lanthanum oxide and 15 to 20 parts by weight of water are uniformly mixed to prepare a reaction substrate, and the reaction substrate is hydrothermally synthesized in a reaction container to obtain a polymetallic tungstate crystalline material with a three-dimensional structure, the hydrothermal synthesis temperature is at least 160°C, and the hydrothermal synthesis time is at least 15 hours.

[0010] The beneficial effects of the present invention relative to the prior art are:

[0011] First, the obtained target product was tested by single crystal diffractometer, and the result showed that the crystal chemical formula of the target product was [Na6(H2O)8Mn2(H2O)6[H2W 12 O 42 ]·4H2O, the crystal belongs to the monoclinic system, the space group is P2(1) / n, and the unit cell parameters are β=109.4080(10) o , Z=2,D c =3.666g / cm 3 The target product is named as a multi-metal tungstate crystalline material with a three-dimensional structure.

[0012] Secondly, the polymetallic tungstate crystal material with a three-dimensional structure can play a catalytic role in the preparation of glutaraldehyde by oxidizing cyclopentene with hydrogen peroxide, and the product yield can reach 63%, showing good catalytic activity.

[0013] Thirdly, the preparation of multi-metal tungstate crystalline materials with three-dimensional structure is achieved by hydrothermal synthesis, which is simple and easy to operate and has a high reaction yield.

[0014] Fourthly, in the preparation method of the polymetallic tungstate crystalline material with a three-dimensional structure, the hydrothermal synthesis temperature is at least 160°C, otherwise the crystalline material cannot be prepared.

[0015] Fifth, as a further manifestation of the beneficial effects: First, the time of hydrothermal synthesis is 24h, and the temperature of hydrothermal synthesis is 180℃, which is conducive to obtaining a higher yield of polymetallic tungstate crystalline materials with a three-dimensional structure. Second, the rate of heating the reaction substrate from room temperature to the hydrothermal synthesis temperature before the start of hydrothermal synthesis is 1-2℃ / min, and the rate of cooling from the hydrothermal synthesis temperature to room temperature after the hydrothermal synthesis is 4-6℃ / h. Lanthanum oxide is used as a mineralizer, which will be conducive to obtaining polymetallic tungstate crystals with better morphology. Third, the reaction container is an autoclave placed in an oven, and the heating before the start of hydrothermal synthesis, the heat preservation during the hydrothermal synthesis, and the cooling after the hydrothermal synthesis are regulated by the oven. The hydrothermal synthesis reaction in the autoclave can make water in a subcritical and supercritical state. At this time, the reaction is at the molecular level and the reactivity is improved. Therefore, the use of an autoclave can better prepare this type of crystalline material than other equipment. The oven can easily adjust the temperature of the hydrothermal reaction, and can also keep the hydrothermal reactor at a suitable heating and cooling rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The following structural drawings further describe the preferred embodiments of the present invention in detail.

[0017] Figure 1 It is a single crystal structure diagram of the product obtained by the present invention (all crystal water molecules and H atoms are omitted).

[0018] Figure 2 It is a two-dimensional layered structure connected by manganese ions in the crystal structure.

[0019] Figure 3 It is a three-dimensional expanded structure diagram of the product.

[0020] Figure 4 This is one of the results of characterizing the target product obtained by the present invention using an infrared spectrometer with a model number of VECTOR22 FT-IR; wherein the horizontal axis is wave number / cm -1 , the vertical axis is transmittance / %. DETAILED DESCRIPTION

[0021] First, buy from the market or prepare by conventional methods:

[0022] Tungstic acid, sodium chloride, sodium tetraborate, manganese chloride, lanthanum oxide, water, 50mL flask, magnetic stirrer, 25mL autoclave, oven.

[0023] then,

[0024] Example 1

[0025] ①. Weigh 0.1g tungstic acid, 0.07g sodium chloride, 0.05g sodium tetraborate, 0.09g manganese chloride and 0.04g lanthanum oxide into a 50mL flask, add 18mL water, place the flask on a magnetic stirrer and stir for 30 minutes.

[0026] ②. Transfer the evenly mixed solution into a 25mL autoclave.

[0027] ③. Place the autoclave in an oven, heat from room temperature to 180°C at a rate of 1.5°C / min, maintain at this temperature for 24 hours, then cool to room temperature at a rate of 5°C / h to obtain Figure 1 , Figure 2 and Figure 3 As shown, Figure 4 The yield of the multi-metal tungstate crystalline material with a three-dimensional structure shown in the curve is about 77%.

[0028] The crystal structure of the target product obtained in this example was determined by single crystal diffractometer, and the results are as follows:

[0029] Crystal data:

[0030]

[0031] Crystalline bond length ( )data:

[0032]

[0033] Crystalline bond angle ( o )data:

[0034]

[0035]

[0036]

[0037] Crystal structure analysis:

[0038] Please also read Figure 1 The crystal structure contains an isopolyacid anion [H2W 12 O 42 ] 10- The anion exhibits a typical paratungstate anion structure, is centrosymmetric, and is composed of two types of trimetallic structural units: two W3O 13 and two W3O 14 Cluster unit. The first type of trimetallic cluster unit W3O 13It is composed of three WO6 octahedrons connected by common edges. The three W atoms form an approximately equilateral triangle structure with angles of 59.25, 59.81 and 60.94°, and the corresponding three side lengths are 3.393, 3.336 and Another trimetallic cluster unit W3O 14 It is an open structure, and the three W atoms form an obtuse angle of 115.87°. In the entire anion cluster, the four trimetallic units are connected by sharing an angle, and the two protons H + Located in [W 12 O 42 ] 12- The center of the metal cluster. Bond valence calculations show that all W has a valence of +6 and Mn has a valence of +2, which is consistent with its chemical formula.

[0039] Please also read Figure 2 , the manganese ion is coordinated with seven oxygen atoms, three of which come from three water molecules, three from three isopoly acid anions, and one from the bridging oxygen in {-Na-O-Mn-}. Each manganese ion is connected to three surrounding isopoly acid anions, so that the isopoly acid anions are connected into a two-dimensional layered structure through the manganese ions.

[0040] Please also read Figure 3 The above two-dimensional layered structure is connected by sodium ions to form a three-dimensional structure that is infinitely extended.

[0041] pass Figure 4 It can be seen that 930, 871, 735 cm in the infrared spectrum -1 The series of absorption peaks at are the characteristic stretching vibration peaks of W=O and WOW. From the infrared spectrum, it can be seen that the vibration position of the absorption peak is consistent with the structural analysis of the target product.

[0042] Example 2

[0043] ①. Weigh 0.1g tungstic acid, 0.07g sodium chloride, 0.05g sodium tetraborate, 0.09g manganese chloride and 0.04g lanthanum oxide into a 50mL flask, add 18mL water, place the flask on a magnetic stirrer and stir for 30 minutes.

[0044] ②. Transfer the evenly mixed solution into a 25mL autoclave.

[0045] ③. Place the autoclave in an oven, heat from room temperature to 160°C at a rate of 1.5°C / min, maintain at this temperature for 18 hours, then cool to room temperature at a rate of 5°C / h to obtain Figure 1 , Figure 2 and Figure 3 As shown, Figure 4The yield of the multi-metal tungstate crystalline material with a three-dimensional structure shown in the curve is about 71%.

[0046] Example 3

[0047] ①. Weigh 0.1g tungstic acid, 0.07g sodium chloride, 0.05g sodium tetraborate, 0.09g manganese chloride and 0.04g lanthanum oxide into a 50mL flask, add 18mL water, place the flask on a magnetic stirrer and stir for 30 minutes.

[0048] ②. Transfer the evenly mixed solution into a 25mL autoclave.

[0049] ③. Place the autoclave in an oven, heat from room temperature to 170°C at a rate of 1.5°C / min, maintain at this temperature for 18 hours, then cool to room temperature at a rate of 5°C / h to obtain Figure 1 , Figure 2 and Figure 3 As shown, Figure 4 The yield of the multi-metal tungstate crystalline material with a three-dimensional structure shown in the curve is about 73%.

[0050] Example 4

[0051] ①. Weigh 0.13g of tungstic acid, 0.05g of sodium chloride, 0.03g of sodium tetraborate, 0.12g of manganese chloride and 0.03g of lanthanum oxide into a 50mL flask, add 20mL of water, place the flask on a magnetic stirrer and stir for 30 minutes.

[0052] ②. Transfer the evenly mixed solution into a 25mL autoclave.

[0053] ③. Place the autoclave in an oven, heat from room temperature to 160°C at a rate of 1.5°C / min, maintain at this temperature for 24 hours, then cool to room temperature at a rate of 5°C / h to obtain Figure 1 , Figure 2 and Figure 3 As shown, Figure 4 The yield of the multi-metal tungstate crystalline material with a three-dimensional structure shown in the curve is about 65%.

[0054] Example 5

[0055] ①. Weigh 0.13g of tungstic acid, 0.05g of sodium chloride, 0.03g of sodium tetraborate, 0.12g of manganese chloride and 0.03g of lanthanum oxide into a 50mL flask, add 20mL of water, place the flask on a magnetic stirrer and stir for 30 minutes.

[0056] ②. Transfer the evenly mixed solution into a 25mL autoclave.

[0057] ③. Place the autoclave in an oven, heat from room temperature to 170°C at a rate of 1.5°C / min, maintain at this temperature for 24 hours, then cool to room temperature at a rate of 5°C / h to obtain Figure 1 , Figure 2 and Figure 3 As shown, Figure 4 The yield of the multi-metal tungstate crystalline material with a three-dimensional structure shown in the curve is about 68%.

[0058] Example 6

[0059] ①. Weigh 0.13g of tungstic acid, 0.05g of sodium chloride, 0.03g of sodium tetraborate, 0.12g of manganese chloride and 0.03g of lanthanum oxide into a 50mL flask, add 20mL of water, place the flask on a magnetic stirrer and stir for 30 minutes.

[0060] ②. Transfer the evenly mixed solution into a 25mL autoclave.

[0061] ③. Place the autoclave in an oven, heat from room temperature to 180°C at a rate of 1.5°C / min, maintain at this temperature for 24 hours, then cool to room temperature at a rate of 5°C / h to obtain Figure 1 , Figure 2 and Figure 3 As shown, Figure 4 The yield of the multi-metal tungstate crystalline material with a three-dimensional structure shown in the curve is about 76%.

[0062] Example 7

[0063] As an application test example, the application of the multi-metal tungstate crystal material with a three-dimensional structure prepared by the present invention in catalyzing the oxidation of cyclopentene with hydrogen peroxide to prepare glutaraldehyde is specifically as follows:

[0064] Take 0.08g of the powdered polymetallic tungstate crystal material (prepared in Example 1) and add it to a round-bottom flask containing 18mL of tert-butyl alcohol and 10mL of cyclopentene. Control the reaction temperature at 36°C and drop 15mL of hydrogen peroxide. After reacting for 6h, filter the solution and perform chromatographic analysis. The results show that the yield of the obtained product glutaraldehyde can reach 63%, showing good catalytic activity.

[0065] Obviously, those skilled in the art can make various changes and modifications to the organic-inorganic hybrid polymolybdate crystalline material and the preparation method thereof without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A polymetallic tungstate crystalline material having a three-dimensional structure, characterized in that The chemical formula of the polymetallic tungstate crystal is [Na6(H2O)8Mn2(H2O)6[H2W 12 O 42 ]·4H2O, the structural formula is as follows: The polymetallic tungstate crystal belongs to the monoclinic system, the space group is P2(1) / n, and the unit cell parameters are β=109.4080(10) o , Z=2,D c =3.666g / cm 3 .

2. A method for preparing the polymetallic tungstate crystalline material with a three-dimensional structure as claimed in claim 1, using a hydrothermal synthesis method, characterized in that: 0.1-0.15 parts by weight of tungstic acid, 0.05-0.08 parts by weight of sodium chloride, 0.02-0.05 parts by weight of sodium tetraborate, 0.07-0.12 parts by weight of manganese chloride, 0.02-0.04 parts by weight of lanthanum oxide and 15-20 parts by weight of water are uniformly mixed to prepare a reaction substrate, and the reaction substrate is hydrothermally synthesized in a reaction container to obtain a multi-metal tungstate crystalline material with a three-dimensional structure, the hydrothermal synthesis temperature is at least 160° C., and the hydrothermal synthesis time is at least 15 hours.

3. The preparation method according to claim 2, characterized in that: The time of hydrothermal synthesis is 24 h, and the temperature of hydrothermal synthesis is 180 °C.

4. The preparation method according to claim 3, characterized in that: Before the hydrothermal synthesis begins, the temperature of the reaction substrate is raised from room temperature to the hydrothermal synthesis temperature at a rate of 1 to 2°C / min.

5. The preparation method according to claim 4, characterized in that: After the hydrothermal synthesis is completed, the cooling rate from the hydrothermal synthesis temperature to room temperature is 4 to 6°C / h.

6. The preparation method according to claim 2, characterized in that: The lanthanum oxide added in the hydrothermal reaction serves as a mineralizer.

7. The preparation method according to claim 2, characterized in that: The reaction container is an autoclave placed in an oven, and the temperature increase before the start of hydrothermal synthesis, the heat preservation during the hydrothermal synthesis, and the temperature reduction after the hydrothermal synthesis are regulated by the oven.

8. Use of the multi-metal tungstate crystal material with a three-dimensional structure as claimed in claim 1 in catalyzing the oxidation of cyclopentene with hydrogen peroxide to prepare glutaraldehyde.

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