Ultrafine mesoporous molybdenum oxide material and preparation method thereof

Abstract

This invention provides an ultrafine intermediate molybdenum oxide material and its preparation method. The method involves placing ammonium molybdate in a reaction vessel and heating it in a vacuum environment at 400℃–600℃ for at least 3 hours to obtain the ultrafine intermediate molybdenum oxide material. The reaction vessel is a sealed structure except for the exhaust end, which is equipped with a one-way gas flow valve. The Fisher particle size of the ultrafine intermediate molybdenum oxide material is 0.8–1.0 micrometers. The method uses a reaction vessel equipped with a one-way gas flow valve, preventing external air from entering during the roasting process while simultaneously allowing the exhaust of gases generated during decomposition, thus ensuring the purity of the obtained molybdenum oxide material. The process conditions are simple and easy to control, making it suitable for industrial production. This material, with its small particle size and high purity, has broad application prospects.

Description

Technical Field

[0001] The present invention belongs to the technical field of chemical raw materials, relates to molybdenum oxide materials, and particularly relates to a superfine intermediate molybdenum oxide material and a preparation method thereof. Background Art

[0002] Intermediate molybdenum oxide MoO 3-x (<0<x<1) is the general name of a series of molybdenum oxides formed by the mixed valence states of molybdenum. The valence of molybdenum is between +5 and +6. This molybdenum oxide has unique properties due to the existence of mixed valence states that single-valence molybdenum oxides do not have. The transfer of electrons during the change of molybdenum valence states causes changes in the color of the compound. Therefore, it has important applications in the colorimetric detection of phosphates, arsenates, silicates and mixtures in sewage, etc. It has broad application prospects in fields such as electrochromic and photochromic smart windows, organic solar cells, supercapacitors and lithium-ion batteries, catalytic reaction processes of hydrogen evolution and organic matter oxidation, etc., and is also an important component of ceramic blue glazes.

[0003] There are different methods for preparing intermediate molybdenum oxide. For example: reacting molybdenum trioxide with an atmosphere having reducing properties (such as hydrogen), and by controlling the ratio of hydrogen / inert atmosphere, hexavalent molybdenum can be reduced to pentavalent molybdenum to form intermediate molybdenum oxide; using molybdenum chloride as a precursor and anhydrous ethanol as a solvent, intermediate molybdenum oxide of molybdenum can be obtained through a solvothermal reaction; intermediate molybdenum oxide can also be prepared by thermally decomposing ammonium molybdate under an inert atmosphere.

[0004] In the methods of the prior art, some require hydrogen and inert gas atmospheres, with high costs and very fine control of the atmosphere; some will introduce other impurities besides molybdenum and oxygen during the preparation process, resulting in a decrease in the purity of molybdenum oxide; there is also a method of using hydrogen peroxide to oxidize molybdenum metal to prepare molybdenum blue, but due to the strong oxidizing property of hydrogen peroxide, it is difficult to obtain intermediate-valence molybdenum oxide, and organic reducing agents often need to be added to achieve it; the process conditions of the above methods are all relatively complex and difficult to control. Summary of the Invention

[0005] Aiming at the defects and deficiencies existing in the prior art, the purpose of the present invention is to provide a superfine intermediate molybdenum oxide material and a preparation method thereof, and solve the technical problem that the process conditions for preparing intermediate molybdenum oxide in the prior art are relatively complex and difficult to control.

[0006] To solve the above technical problems, the present invention adopts the following technical solutions to achieve:

[0007] A method for preparing ultrafine intermediate molybdenum oxide material, wherein the raw material ammonium molybdate is placed in a reaction vessel and heated in a vacuum environment at a temperature of 400℃~600℃ for at least 3 hours to obtain ultrafine intermediate molybdenum oxide material; the reaction vessel is a sealed structure except for the exhaust end, and a one-way gas flow valve is installed in the exhaust end.

[0008] The present invention also has the following technical features:

[0009] Specifically and optionally, the reaction vessel is a muffle furnace; the exhaust pipe of the muffle furnace is the exhaust end, and the furnace body except for the exhaust pipe is a sealed structure, with a one-way flow valve installed in the exhaust pipe.

[0010] Specifically and optionally, the reaction vessel is a tubular furnace; one end of the tubular furnace is the exhaust end, and the furnace body except for the exhaust end is a sealed structure, with a one-way flow valve installed in the exhaust end.

[0011] Specifically, the heating process is as follows: first, raise the temperature to 400℃ and hold for 1 hour; then raise the temperature to 500℃ and hold for 2 hours; finally, raise the temperature to 530-550℃ and hold for 1.5-2 hours.

[0012] Specifically, the raw material ammonium molybdate is ammonium octamolybdate.

[0013] Specifically, the raw material ammonium molybdate has a Fisher particle size of 1.0 to 1.5 micrometers.

[0014] This invention also protects an ultrafine intermediate molybdenum oxide material, which is prepared by the method described above for preparing ultrafine intermediate molybdenum oxide materials.

[0015] Specifically, the Fisher particle size of this ultrafine intermediate molybdenum oxide material is 0.8–1.0 micrometers.

[0016] The beneficial technical effects of this invention compared to the prior art are as follows:

[0017] (I) Compared with existing technologies, the preparation method of the ultrafine intermediate molybdenum oxide material of the present invention does not require the use of hydrogen for reduction or an inert protective atmosphere, and does not introduce other impurities during preparation. This method uses a reaction vessel equipped with a one-way gas flow valve, preventing external air from entering during the calcination process while simultaneously venting gases generated during decomposition, thus ensuring the purity of the obtained molybdenum oxide material. The process conditions of this method are simple, easy to control, and suitable for industrial production.

[0018] (II) The ultrafine intermediate molybdenum oxide material of the present invention has small particle size, high purity, and broad application prospects. Attached Figure Description

[0019] Figure 1This is a SEM image of an ultrafine intermediate molybdenum oxide material.

[0020] Figure 2 The image shows the XRD pattern of the ultrafine intermediate molybdenum oxide material.

[0021] The technical solution of the present invention will be further described below with reference to the embodiments. Detailed Implementation

[0022] Under normal conditions, ammonium molybdate decomposes into molybdenum trioxide at 400℃~600℃, releasing ammonia and water.

[0023] (NH4)4Mo8O 26 →8MoO3+4NH3↑+2H2O↑

[0024] With proper ventilation, ammonia and water are promptly expelled, resulting in white or light-colored molybdenum trioxide. However, when ventilation is inadequate, ammonia and water cannot be expelled in time, and ammonia undergoes slight decomposition above 400℃ (the reverse reaction for ammonia synthesis).

[0025] 2NH3→3H2+N2

[0026] The hydrogen gas can reduce the product molybdenum trioxide. Since the amount of hydrogen gas is very small, it reduces molybdenum trioxide to MoO. 3-x Molybdenum oxide in intermediate valence states.

[0027] In this invention, a vacuum environment refers to an environment with a vacuum level of 0.02 MPa to 0.09 MPa.

[0028] It should be noted that all raw materials, components and equipment used in this invention, unless otherwise specified, are those known in the art. For example, the one-way airflow valve is a one-way airflow valve known in the prior art.

[0029] Following the above technical solutions, specific embodiments of the present invention are given below. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent modifications made based on the technical solutions of this application fall within the protection scope of the present invention.

[0030] Example 1:

[0031] This embodiment provides a method for preparing ultrafine intermediate molybdenum oxide materials. The specific process of this method is as follows:

[0032] Take 200g of ammonium octamolate with a Fisher particle size of 1.0 micrometer and place it in a crucible. Place the crucible containing the ammonium octamolate in a muffle furnace, evacuate the furnace, raise the temperature to 400℃ and hold for 1 hour; then raise the temperature to 500℃ and hold for 2 hours; finally raise the temperature to 530℃ and hold for 1.5 hours, then lower the temperature. After the temperature drops below 30℃, take out the product, which is a blue-gray powdery solid.

[0033] As a specific embodiment, the muffle furnace has an exhaust pipe, and the furnace body except for the exhaust pipe is a sealed structure. A one-way airflow valve is installed in the exhaust pipe.

[0034] In this embodiment, the raw material ammonium molybdate decomposes into molybdenum oxide, ammonia, and water vapor upon heating. The muffle furnace designed above can discharge the ammonia and water vapor generated during the roasting of ammonium molybdate through an exhaust pipe. Because a one-way airflow valve is installed in the exhaust pipe, external air cannot enter the furnace.

[0035] In this embodiment, the particle size of the blue-gray powder solid was tested using a Fisher particle size analyzer, and its Fisher particle size was measured to be 0.8 micrometers.

[0036] Example 2:

[0037] This embodiment provides a method for preparing ultrafine intermediate molybdenum oxide materials. The specific process of this method is as follows:

[0038] Take 150g of ammonium octamolate with a Fisher particle size of 1.2 micrometers and place it in a crucible. Place the crucible containing the ammonium octamolate in a tube furnace, evacuate the furnace, raise the temperature to 400℃ and hold for 1 hour; then raise the temperature to 500℃ and hold for 2 hours; finally raise the temperature to 550℃ and hold for 2 hours, then lower the temperature. After the temperature drops below 30℃, take out the product, which is a blue-gray powdery solid.

[0039] As a specific embodiment, one end of the tubular furnace is the exhaust end, and the other end of the tubular furnace is a sealed structure, with a one-way airflow valve installed inside the exhaust end.

[0040] In this embodiment, the tubular furnace designed above can discharge the ammonia and water vapor generated by the roasting of ammonium molybdate through one end of the tubular furnace. Since a one-way airflow valve is installed inside one end of the tubular furnace, external air cannot enter the furnace body.

[0041] In this embodiment, the particle size of the blue-gray powder solid was tested using a Fisher particle size analyzer, and its Fisher particle size was measured to be 1.0 micrometers.

[0042] Product identification:

[0043] The final obtained blue-gray powdery solid was identified using SEM and XRD. The SEM results are shown in [Figure number missing]. Figure 1 XRD such as Figure 2 As shown. Figure 1 The microstructure of this bluish-gray powdery solid is shown. Figure 2 The XRD pattern corresponds to JCPDS card number 74-1648, indicating that the powder is MoO. 2.5 (OH) 0.5The bluish-gray powdery solid is an intermediate state molybdenum oxide, and it is ultimately named an ultrafine intermediate state molybdenum oxide material. This material needs to be vacuum-packed to prevent it from oxidizing in the air.

[0044] The purity of the ultrafine intermediate molybdenum oxide material finally obtained by this invention is ≥99.95%.

Claims

1. A method for preparing an ultrafine meso-oxidic molybdenum material, characterized in that, Ammonium molybdate was placed in a reaction vessel and heated to 400°C in a vacuum environment for 1 hour; then heated to 500°C for 2 hours; and finally heated to 530–550°C for 1.5–2 hours to obtain ultrafine intermediate molybdenum oxide material. The reaction vessel is a muffle furnace or a tube furnace; When the reaction vessel is a muffle furnace, the exhaust pipe of the muffle furnace is the exhaust end, and the furnace body except for the exhaust pipe is a sealed structure. A one-way flow valve is installed in the exhaust pipe. When the reaction vessel is a tubular furnace, one end of the tubular furnace is the exhaust end, and the furnace body except for the exhaust end is a sealed structure. A one-way flow valve is installed in the exhaust end. The raw material ammonium molybdate is ammonium octamolybdate; The raw material ammonium octamolybdate has a Fisher particle size of 1.0–1.5 micrometers; The Fisher particle size of this ultrafine intermediate molybdenum oxide material is 0.8–1.0 micrometers.

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