Vanadium-phosphorus composite oxide material as well as preparation method and application thereof

Abstract

The invention discloses a vanadium-phosphorus composite oxide material. The composition of the composite oxide is VPxMyOz, wherein M is one of Ti, Mo, Fe, Co, Ni, Mn, Sb, Bi, B, alkali metal and alkaline earth metal; x is equal to 0.1-2 and is the atom molar ratio of phosphorus to vanadium; y is equal to 0-1.2 and is the atom molar ratio of M to vanadium; z is determined according to the valence state of atoms; the composite oxide material is a porous microsphere formed by assembling blocky or flaky nanoparticles, and the diameter of the microsphere is 5-100 microns. The invention also discloses a preparation method and application of the material. The vanadium-phosphorus composite oxide prepared by taking vanadium and phosphorus compounds and compounds of other elements as raw materials and amino acid compounds as auxiliary reagents can be self-assembled to form a porous micron spherical structure, is uniform in particle size distribution and large in specific surface area, is used for preparing aromatic nitrile through ammoxidation reaction of methyl aromatic hydrocarbon, and is low in ammoxidation reaction temperature and high in ammoxidation efficiency. The reaction activity is high and the selectivity is good.

Description

Technical Field

[0001] The present invention belongs to the fields of materials and chemical engineering, and particularly relates to a vanadium-phosphorus composite oxide material, a preparation method thereof, and an application thereof. Background Art

[0002] Vanadium-phosphorus composite oxide is an important inorganic functional material in the fields of materials and chemical engineering, and can be applied to fields such as catalysis, battery electrode materials, capacitor materials, sensors, etc. As a catalytic material, it has good dispersion and catalytic carbonization effects; as a battery material, it can be used to prepare excellent lithium battery, sodium battery, and magnesium battery electrode materials, which can improve electrochemical performance.

[0003] There are various main methods for synthesizing vanadium-phosphorus composite oxide. For example, through the dehydration method, vanadyl phosphate dihydrate can be dehydrated in one step under a flowing helium atmosphere to obtain VOPO4 (G. He, W. H. Kan, A. Manthiram, Chemistry of Materials 28(2)(2016)682 - 688.); or through flame spray synthesis, a certain amount of ammonium vanadate and ammonium dihydrogen phosphate are prepared into a solution, and an organic component is added to generate a self-sustaining flame during the reaction to obtain VOPO4 (G. Jodhani, F. Mikaeili, P. I. Gouma, Frontiers in Materials 6(2019)254.); it can also be obtained through solvothermal reaction. Using methanol as a solvent, vanadium pentoxide and phosphoric acid are added and subjected to solvothermal reaction at 180°C to obtain VOPO4 (M. Amedzo-Adore, J. I. Han, Ceramics International 48(18)(2022)26226 - 26232.). The materials prepared by these methods have low crystallinity, irregular morphology, and small specific surface area, which result in few surface active centers of the microparticles, small contact surfaces for chemical reactions, and low reaction activity, thus limiting its application scope. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a porous micron-sized spherical vanadium-phosphorus composite oxide VP x M y O z material, which is formed by stacking blocky or flaky nanoparticles, has uniform size, and the diameter of the microspheres is 5 - 100 μm. The porous micron-sized spherical vanadium-phosphorus composite oxide material has good catalytic effect as a catalyst for catalytic ammoxidation reaction. The porous micron-sized spherical vanadium-phosphorus composite oxide material of the present invention is prepared by the following method:

[0005] The active component source and the auxiliary agent are placed in a pressure vessel, water is added as a solvent and mixed evenly. After sealing, the temperature is raised to 120 - 300 °C, and a solvothermal reaction is carried out for 2 - 200 hours. The product is filtered, washed, and dried in vacuum to obtain a precursor; the active component source includes a vanadium source and a phosphorus source.

[0006] The precursor is calcined at a temperature of 300 - 800 °C for 0.1 - 10 hours and cooled to room temperature to obtain a porous micron-sized spherical vanadium phosphorus composite oxide.

[0007] The vanadium source is a vanadium oxide and / or a vanadium salt, and the phosphorus source is a phosphorus oxide, phosphoric acid, or phosphate.

[0008] The active component source further includes a third component source, and the third component is one of a titanium source, a molybdenum source, an iron source, a cobalt source, a nickel source, a manganese source, an antimony source, a bismuth source, a boron source, an alkali metal source, and an alkaline earth metal source.

[0009] The composition of the vanadium phosphorus composite oxide is VP x M y O z , where x = 0.1 - 2, which is the atomic molar ratio of phosphorus to vanadium; y = 0 - 1.2, which is the atomic molar ratio of the third component to vanadium; z is determined according to the atomic valence state.

[0010] The vanadium oxides include but are not limited to at least one of V2O5, V2O4, and V2O3, and the vanadium salts include but are not limited to at least one of NH4VO3, VOSO4, and VOCl2; the phosphorus source is at least one of P4O6, P2O5, H3PO4, (NH4)2HPO4, (NH4)H2PO4, and (NH4)3PO4; the chromium oxides are at least one of Cr2O3 and CrO3; the titanium source is TiCl4, TiCl3, or TiO2, etc.; the molybdenum source is MoO3, (NH4)6Mo7O 24etc.; the iron source is FeCl3, Fe2O3, Fe3O4, Fe(NO3)3·9H2O, Fe(OAc)2, FeC2O4·2H2O, Fe2(C2O4)3·6H2O, etc.; the cobalt source is Co(OAc)2, Co(NO3)2·6H2O, Co3O4, CoCl2, etc.; the nickel source is NiCl2·6H2O, Ni(NO3)2·6H2O, etc.; the manganese source is MnO2, MnCl2, Mn(NO3)2, etc.; the antimony source is Sb2O3, Sb2O5, H3SbO4, Sb(NO3)3, SbCl3, SbCl5, (SbO)2SO4, antimony acetate, ammonium oxalatoantimonate, potassium antimonyl tartrate, sodium antimonyl tartrate, tartaric acid antimonate, etc.; the bismuth source is Bi(NO3)3, BiCl3, Bi2O3, etc.; the boron source is H3BO3, B2O3, etc.; the alkali metal source is its oxide, hydroxide, nitrate, carbonate, oxalate, sulfate, chloride, etc.; the alkaline earth metal source is its oxide, hydroxide, nitrate, carbonate, oxalate, sulfate, chloride, etc.

[0011] The auxiliary agent is an amino acid, including but not limited to α-, β-, γ-amino acids, etc.; the molar ratio of the auxiliary agent to vanadium is 0.1-10.

[0012] The pressure vessel is an autoclave or a pressure-resistant reactor.

[0013] The solvothermal reaction temperature is 160-240 °C and the time is 12-72 hours.

[0014] The porous microspherical vanadium-phosphorus composite oxide provided by the present invention can be used for catalytic ammoxidation of methylarene to prepare aromatic nitrile.

[0015] The methylarene includes toluene, halogenated toluene, methoxytoluene, hydroxytoluene, nitrotoluene, cyanotoluene, aminotoluene, xylene, methylpyridine, methylpyrazine or methylpyrimidine.

[0016] The present invention uses vanadium, phosphorus compounds and compounds of other elements as raw materials, amino acid compounds as auxiliary reagents, and water as a solvent to carry out a solvothermal reaction in a pressure vessel. The prepared vanadium-phosphorus binary or ternary composite oxide can self-assemble into a porous microspherical structure. The particle size distribution of the microsphere material is uniform, the specific surface area is large, the catalyst preparation method is simple, the raw materials are easy to obtain, the cost is low, and it is suitable for large-scale preparation; when the vanadium-phosphorus composite oxide with this structure is used for the ammoxidation of methylarene to prepare aromatic nitrile, the ammoxidation reaction temperature is 300-420 °C; compared with other vanadium-based catalysts, not only the reaction temperature is significantly reduced, but also the reaction activity is significantly increased by 5-40%, and the selectivity is also greatly improved. Description of the Drawings

[0017] Figure 1 Scanning electron microscope image (20-μm scale bar) of the porous microspherical VOPO4 precursor obtained in the present invention.

[0018] Figure 2 Scanning electron microscope image (5-μm scale bar) of the porous microspherical VOPO4 precursor obtained in the present invention.

[0019] Figure 3 Scanning electron microscope image (5-μm scale bar) of the porous microspherical VOPO4 obtained in the present invention.

[0020] Figure 4 Scanning electron microscope image (2-μm scale bar) of the porous microspherical VOPO4 obtained in the present invention.

[0021] Figure 5 XRD pattern (PDF#27-0948) of the porous microspherical VOPO4 obtained in the present invention. Detailed Description of the Invention

[0022] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0023] Example 1

[0024] Weigh 2.50 g of V2O5, 3.17 g of H3PO4 (85%) and 2.27 g of phenylalanine according to the molar ratio of V:P:phenylalanine = 1:1:0.5, place them in a beaker, then add 5.20 g of oxalic acid and 80 ml of distilled water, stir well to mix evenly, heat the reaction in a water bath until no bubbles are generated, transfer the obtained dark blue solution into a hydrothermal reaction kettle with a Teflon liner with a volume of 100 ml, seal the reaction kettle, place it in an electric resistance furnace and heat it to 180 °C, keep the temperature constant for 24 h, and then cool it naturally to room temperature. Filter the product in the reaction kettle, wash it repeatedly with distilled water and ethanol respectively, and then dry it in vacuum at 70 °C for 12 h to obtain an amorphous spherical VOPO4 precursor. The precursor is calcined in a muffle furnace at 550 °C for 2 h to obtain a porous microsphere assembled from nano-VOPO4. Figure 1 And 2 Scanning electron microscope image of the VOPO4 precursor obtained in this example. It can be seen that the precursor is a solid spherical structure with a size of 20-30 μm; Figure 3 And 4 Scanning electron microscope image of the obtained porous microspherical VOPO4. It can be seen that a porous spherical structure with a size of 20-30 μm is formed after the precursor is calcined; Figure 5 XRD pattern of the obtained porous microspherical VOPO4. The catalyst is an orthorhombic VOPO4 crystal structure.

[0025] Example 2

[0026] This example is a control example.

[0027] The preparation method and treatment method of the catalyst are the same as those in Example 1. The difference is that no phenylalanine additive is added. The obtained catalyst precursor is amorphous. After calcination at 550 °C for 2 h, VOPO4 is obtained, which is not spherical and has poor dispersion. The material has no complete morphology, the particle sizes of the microparticles are different, and the specific surface area is small.

[0028] Example 3

[0029] Weigh NH4VO3, KH2PO4 and tryptophan with a total mass of 5.0 g according to the molar ratio of vanadium, phosphorus and additive of 1:0.5:1 and place them in a hydrothermal reaction kettle with a polytetrafluoroethylene liner with a volume of 100 ml. Then add 80 ml of water and stir well to mix evenly. After sealing, put the reaction kettle into an electric resistance furnace and heat it to 240 °C. After isothermal hydrothermal treatment for 36 h, it is naturally cooled to room temperature. Filter the product in the reaction kettle and wash it repeatedly with distilled water and ethanol, and then dry it in vacuum at 70 °C for 8 h to obtain an amorphous VPK composite oxide precursor. The precursor is calcined in an electric resistance furnace at 550 °C for 3 h to obtain VP 0.5 K 0.5 O4 composite oxide porous microspheres.

[0030] Example 4

[0031] Weigh VOSO4, P4O6, H3BO3 and β-alanine with a total mass of 6.0 g according to the molar ratio of vanadium, phosphorus, boron and additive of 1:0.8:0.2:3 and place them in a hydrothermal reaction kettle with a polytetrafluoroethylene liner with a volume of 100 ml. Then add 80 ml of distilled water and stir well to mix evenly. After sealing, put the reaction kettle into an electric resistance furnace and heat it to 220 °C. After isothermal hydrothermal treatment for 24 h, it is naturally cooled to room temperature. Filter the product in the reaction kettle and wash it repeatedly with distilled water and ethanol, and then dry it in vacuum at 70 °C for 12 h to obtain an amorphous VPB composite oxide precursor. The precursor is calcined in an electric resistance furnace at 630 °C for 2 h to obtain VP 0.8 B 0.2 O 4.8 composite oxide porous microspheres.

[0032] Example 5

[0033] Weigh V2O3, H3PO4, Ni(NO3)2 and γ-aminobutyric acid with a total mass of 5.0 g according to the molar ratio of vanadium, phosphorus, nickel and promoter of 1:1:0.1:0.5, and place them in a hydrothermal reactor with a PTFE liner with a volume of 100 ml. Then add 80 ml of distilled water, stir well to mix evenly, seal the reactor, and place it in an electric resistance furnace and heat it to 180 °C. After isothermal hydrothermal treatment for 48 h, naturally cool it to room temperature. Filter the product in the reactor, wash it repeatedly with distilled water and ethanol respectively, and then dry it in vacuum at 70 °C for 12 h to obtain an amorphous VPNi composite oxide precursor. The precursor is calcined in an electric resistance furnace at 600 °C for 2 h to obtain VPNi 0.1 O 5.1 Composite oxide porous microspheres.

[0034] Example 6

[0035] Charge 10 g of the VOPO4 porous microspheres prepared in Example 1 into a quartz tube fixed-bed reactor with an inner diameter of 30 mm. Preheat and mix p-methoxytoluene, ammonia and air in a molar ratio of 1:5:20 and then pass them through the catalyst bed for reaction. The reaction temperature is 350 °C. After 8 hours of reaction, the conversion rate of p-methoxytoluene is 86.7%, and the molar yield of anisic nitrile is 75.1%.

[0036] Using the VOPO4 prepared in Example 2 as the catalyst, when the reaction temperature is 400 °C, after 8 hours of reaction, the conversion rate of p-methoxytoluene is 73.1%, and the molar yield of anisic nitrile is 55.7%.

[0037] Example 7

[0038] Charge 10 g of the VP 0.5 K 0.5 O4 composite oxide porous microspheres prepared in Example 3 into a quartz tube fixed-bed reactor with an inner diameter of 30 mm. Preheat and mix 3-methylpyridine, ammonia and air in a molar ratio of 1:3:20 and then pass them through the catalyst bed for reaction. The reaction temperature is 325 °C. After 8 hours of reaction, the conversion rate of 3-methylpyridine is 94.7%, and the molar yield of 3-cyanopyridine is 88.7%.

[0039] Using the VOPO4 prepared in Example 2 as the catalyst, when the reaction temperature is 360 °C, after 8 hours of reaction, the conversion rate of 3-methylpyridine is 95.9%, and the molar yield of 3-cyanopyridine is 75.5%.

[0040] Example 8

[0041] Charge 10 g of the VP 0.5 K 0.5O4 composite oxide porous microspheres. p-Methoxytoluene, ammonia, and air are preheated and mixed in a molar ratio of 1:5:20 and then passed through the catalyst bed for reaction. The reaction temperature is 325 °C. After 8 hours of reaction, the conversion rate of p-methoxytoluene is 92.3%, and the molar yield of p-methoxybenzonitrile is 84.5%.

[0042] Example 9

[0043] 15 g of the VP prepared in Example 4 is loaded into a quartz tube fixed-bed reactor with an inner diameter of 30 mm 0.8 B 0.2 O 4.8 Composite oxide porous microspheres. 2,6-Dichlorotoluene, ammonia, and air are preheated and mixed in a molar ratio of 1:4:15 and then passed through the catalyst bed for reaction. The reaction temperature is 340 °C. After 8 hours of reaction, the conversion rate of 2,6-dichlorotoluene is 90.1%, and the molar yield of 2,6-dichlorobenzonitrile is 78.1%.

[0044] Using the VOPO4 prepared in Example 2 as the catalyst, when the reaction temperature is 400 °C, after 8 hours of reaction, the conversion rate of 2,6-dichlorotoluene is 93.6%, and the molar yield of 2,6-dichlorobenzonitrile is 59.8%.

[0045] Example 10

[0046] 10 g of the VPNi prepared in Example 5 is loaded into a quartz tube fixed-bed reactor with an inner diameter of 30 mm 0.1 O 5.1 Composite oxide porous microspheres. 2-Methylpyrazine, ammonia, and air are preheated and mixed in a molar ratio of 1:5:25 and then passed through the catalyst bed for reaction. The reaction temperature is 320 °C. After 8 hours of reaction, the conversion rate of 2-methylpyrazine is 94.4%, and the molar yield of 2-cyanopyrazine is 82.4%.

[0047] Using the VOPO4 prepared in Example 2 as the catalyst, when the reaction temperature is 380 °C, after 8 hours of reaction, the conversion rate of 2-methylpyrazine is 96.2%, and the molar yield of 2-cyanopyrazine is 63.1%.

Claims

1. A vanadium-phosphorus composite oxide material, characterized in that: The composition of the composite oxide is VP x M y O z , M is one of Ti, Mo, Fe, Co, Ni, Mn, Sb, Bi, B, alkali metal and alkaline earth metal; 0.1≤x≤2 is the atomic molar ratio of phosphorus to vanadium; 0≤y≤1.2 is the atomic molar ratio of M to vanadium; z depends on the atomic valence state; the composite oxide material is a porous microsphere formed by assembling block or flaky nanoparticles, and the diameter of the microsphere is 5-100μm.

2. A method for preparing a vanadium-phosphorus composite oxide material, characterized in that: The method comprises the following steps: 1) placing an active component source and an auxiliary agent in a pressure vessel, adding water as a solvent and mixing evenly, and finally sealing and heating to 120-300° C., performing a solvent thermal reaction for 2-200 hours, filtering, washing, and vacuum drying the product to obtain a precursor; the active component source includes a vanadium source and a phosphorus source; 2) calcining the precursor at 300-800° C. for 0.1-10 hours and cooling to room temperature to obtain porous micron-shaped spherical vanadium-phosphorus composite oxide.

3. The method for preparing the vanadium-phosphorus composite oxide material according to claim 2, characterized in that: The vanadium source is vanadium oxide and / or vanadium salt, and the phosphorus source is phosphorus oxide, phosphoric acid or phosphate.

4. The method for preparing the vanadium-phosphorus composite oxide material according to claim 2, characterized in that: The active component source also includes a third component source, and the third component is one of a titanium source, a molybdenum source, an iron source, a cobalt source, a nickel source, a manganese source, an antimony source, a bismuth source, a boron source, an alkali metal source, and an alkaline earth metal source; the composition of the vanadium-phosphorus composite oxide is VP x M y O z , the 0.1≤x≤2 is the atomic molar ratio of phosphorus to vanadium; 0<y≤1.2 is the atomic molar ratio of the third component to vanadium; z is determined according to the atomic valence state.

5. The method for preparing the vanadium-phosphorus composite oxide material according to claim 2 or 4, characterized in that: The vanadium oxides include but are not limited to at least one of V2O5, V2O4 and V2O3; the vanadium salts include but are not limited to at least one of NH4VO3, VOSO4 and VOCl2; the phosphorus source is at least one of P4O6, P2O5, H3PO4, (NH4)2HPO4, (NH4)H2PO4 or (NH4)3PO4.

6. The method for preparing the vanadium-phosphorus composite oxide material according to claim 4, characterized in that: The titanium source is TiCl4, TiCl3 or TiO2; the molybdenum source is MoO3 or (NH4)6Mo7O 24 ; The iron source is FeCl3, Fe2O3, Fe3O4, Fe(NO3)3·9H2O, Fe(OAc)2, FeC2O4·2H2O or Fe2(C2O4)3·6H2O; the cobalt source is Co(OAc)2, Co(NO3)2·6H2O, Co3O4 or CoCl2; the nickel source is NiCl2·6H2O or Ni(NO3)2·6H2O; the manganese source is MnO2, MnCl2 or Mn(NO3)2; the antimony source is Sb2O3, Sb2O5, H3SbO4, Sb(NO3)3, SbCl3, SbCl5, (SbO)2SO4, antimony acetate, ammonium antimony oxalate, potassium antimony tartrate, sodium antimony tartrate or antimony tartrate; the bismuth source is Bi(NO3)3, BiCl3 or Bi2O3; the boron source is H3BO3 or B2O3; the alkali metal source is an oxide, hydroxide, nitrate, carbonate, oxalate, sulfate or chloride of an alkali metal; the alkaline earth metal source is an oxide, hydroxide, nitrate, carbonate, oxalate, sulfate or chloride of an alkaline earth metal.

7. The method for preparing the vanadium-phosphorus composite oxide material according to claim 2 or 4, characterized in that: The auxiliary agent is an amino acid, including but not limited to α-amino acid, β-amino acid and γ-amino acid; the molar ratio of the auxiliary agent to vanadium is 0.1-10.

8. The method for preparing the vanadium-phosphorus composite oxide material according to claim 2 or 4, characterized in that: The solvent thermal reaction temperature is 160 to 240° C. and the reaction time is 12 to 72 hours.

9. Use of the vanadium-phosphorus composite oxide material according to claim 1 in catalyzing the ammoxidation reaction of methyl aromatic hydrocarbons to prepare aromatic nitriles.

10. The use according to claim 9, characterized in that: The methyl aromatic hydrocarbons include toluene, halogenated toluene, methoxytoluene, hydroxytoluene, nitrotoluene, cyanotoluene, aminotoluene, xylene, picoline, methylpyrazine and methylpyrimidine.

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