Preparation method of rhenium trioxide and rhenium dioxide

Abstract

The invention discloses a preparation method of rhenium trioxide and rhenium dioxide, which comprises the following steps of: 1, dissolving ammonium perrhenate in deionized water to prepare an ammonium perrhenate solution, and enabling the ammonium perrhenate solution to flow through an exchange column filled with H + type C160 cationic resin to obtain a perrhenic acid solution; 2, ammonium perrhenate is subjected to hydrogen reduction, and active rhenium powder is obtained; 3, mixing and drying the perrhenic acid solution and the active rhenium powder to obtain a rhenium oxide precursor; and 4, thermally decomposing the rhenium oxide precursor in an inert atmosphere to obtain a rhenium trioxide or rhenium dioxide solid. According to the method, ammonium perrhenate is subjected to cationic resin ion exchange and hydrogen reduction treatment to obtain a perrhenic acid solution and active rhenium powder respectively, then the perrhenic acid solution and the active rhenium powder are evenly mixed, dried and subjected to thermal decomposition, and cubic-crystal-form rhenium trioxide or orthorhombic-crystal-form rhenium dioxide solids are obtained; the crystal form of rhenium dioxide is effectively controlled, the raw materials are easier to obtain and store, the difficulty of the preparation process is reduced, and the method is suitable for large-scale production.

Description

Technical Field

[0001] This invention belongs to the field of rhenium trioxide and rhenium dioxide synthesis technology, specifically relating to a method for preparing rhenium trioxide and rhenium dioxide. Background Technology

[0002] Rhenium is a strategic refractory metal, and its important oxides include rhenium trioxide and rhenium dioxide. Rhenium trioxide (ReO3) is a red solid, mainly used as a catalyst in organic synthesis reactions such as amides and methyl acetals. Due to its high conductivity and infrared reflection properties, ReO3 has significant application prospects in conductive coatings and optical filters. Rhenium trioxide was initially prepared at 300°C by reacting metallic rhenium with rhenium heptaoxide, requiring repeated grinding and heating of the reactants, resulting in a complex and time-consuming process and inconsistent product composition. Currently, rhenium trioxide is mainly prepared by reducing rhenium heptaoxide with carbon monoxide or methanol; alternatively, rhenium trioxide can also be obtained by the thermal decomposition of complexes formed by rhenium heptaoxide with dioxane or tetrahydrofuran. Japanese Patent JP3956400B2 reports a method of dissolving one or more heptavalent rhenium compounds, such as rhenium heptaoxide, perrhenic acid, and ammonium perrhenate, in various alcohols, ketones, or amines. The mass percentage concentration of the solution is controlled to be below 27%. The solution is then heated in air or a nitrogen atmosphere to evaporate to dryness, followed by washing and drying to obtain fine rhenium trioxide particles with a particle size of less than 100 nm. All of the above methods for preparing rhenium trioxide use toxic carbon monoxide and organic reagents, resulting in a harsh production environment.

[0003] Rhenium dioxide (ReO2) is a brownish-black solid primarily used as a catalyst in petroleum reforming and hydrogenation reactions. Currently, rhenium dioxide is mainly prepared through the thermal decomposition of ammonium perrhenate under an inert atmosphere. Chinese patent CN117123790A discloses a method of first ball-milling and sieving crude ammonium perrhenate, followed by calcination and decomposition in a tube furnace under nitrogen to obtain rhenium dioxide. This method produces rhenium dioxide with both monoclinic and orthorhombic ReO2 crystal forms, leading to a decrease in its catalytic performance. In addition, Chinese patent CN118663913A discloses the use of MOFs as catalysts and the use of electron beams or gamma rays to radiate and reduce ammonium perrhenate solution to obtain single-component ReO2. The rhenium dioxide particles obtained by this method are small and do not settle easily. Strong electrolytes need to be added to make ReO2 aggregate. The aggregation process is time-consuming and requires expensive cobalt source chambers or electron accelerators to generate gamma rays or electron beams. The equipment cost is high and it is not suitable for the large-scale production of rhenium dioxide. Summary of the Invention

[0004] The technical problem to be solved by this invention is to provide a method for preparing rhenium trioxide and rhenium dioxide, addressing the shortcomings of the prior art. This method involves treating ammonium perperurate with cation exchange resin and hydrogen reduction to obtain a perperuric acid solution and activated rhenium powder, respectively. The two are then mixed, dried, and thermally decomposed to obtain cubic rhenium trioxide or orthorhombic rhenium dioxide solids. This method solves the problems of the hazards of using organic reagents and carbon monoxide in existing rhenium trioxide preparation processes, as well as the issue of rhenium dioxide exhibiting a mixed monoclinic and orthorhombic crystal form.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a method for preparing rhenium trioxide and rhenium dioxide, characterized in that the method includes the following steps: Step 1: Dissolve ammonium perrhenate in deionized water to prepare an ammonium perrhenate solution, then flow the ammonium perrhenate solution through a container filled with H... + An exchange column of type C160 cation exchange resin was used to obtain a perrhenic acid solution; the mass concentration of rhenium in the perrhenic acid solution was 16 g / L to 35 g / L. Step 2: Ammonium perrhenate is reduced with hydrogen to obtain activated rhenium powder; the average particle size of the activated rhenium powder is 10μm~50μm; Step 3: Mix the perrhenic acid solution obtained in Step 1 with the active rhenium powder obtained in Step 2 in a certain proportion and dry it in an air atmosphere to obtain the rhenium oxide precursor; the volume ratio of the perrhenic acid solution to the mass ratio of the active rhenium powder is 100mL~400mL:1g. Step 4: The rhenium oxide precursor obtained in Step 3 is thermally decomposed under an inert atmosphere to obtain rhenium trioxide or rhenium dioxide solid; when the thermal decomposition temperature is 300℃~500℃, rhenium trioxide solid is obtained, and when the thermal decomposition temperature is 600℃~800℃, rhenium dioxide solid is obtained.

[0006] This invention obtains a rhenium oxide precursor by drying perrhenic acid and active rhenium powder at low temperature, as shown in the following reaction formula: 6HReO4+Re+(7n-3)H2O→7ReO3·nH2O; The rhenium oxide precursor is then thermally decomposed under an inert atmosphere. Specifically, thermal decomposition at 300℃~500℃ yields solid rhenium trioxide, and thermal decomposition at 600℃~800℃ yields solid rhenium dioxide. The reaction equations are as follows: ; .

[0007] This invention avoids low product yield and excessively long drying time by controlling the mass concentration of rhenium in the perrhenic acid solution; by controlling the particle size of the activated rhenium powder and the ratio of the volume of the perrhenic acid solution to the mass of the activated rhenium powder, it ensures complete reaction between Re and HReO4 and eliminates the adverse effects of residual rhenium powder in the product; at the same time, it eliminates the need to use organic reagents such as carbon monoxide or methanol, and obtains a single-phase component of rhenium trioxide or rhenium dioxide solid.

[0008] The above-mentioned method for preparing rhenium trioxide and rhenium dioxide is characterized in that, in step one, the ammonium perrhenate solution flows through a container filled with H... + The flow rate of the C160 cation exchange column is 2 BVs / h to 4 BVs / h, and the ammonium perrhenate solution reacts with H... + The volume ratio of the C160 cation exchange resin is 5:1 to 10:1. This invention controls the exchange flow rate of the ammonium perrhenate solution and the volume ratio of the ammonium perrhenate solution to the resin, ensuring the complete conversion of ammonium perrhenate to perrhenic acid and eliminating NH4+. + Adverse effects on the rhenium trioxide and rhenium dioxide phase components of the product.

[0009] The method for preparing rhenium trioxide and rhenium dioxide described above is characterized in that the hydrogen reduction in step two is carried out at a temperature of 800℃~1000℃ for 1h~4h. This invention, by controlling the temperature and time of hydrogen reduction, ensures the complete conversion of ammonium perrhenate into active rhenium powder, which is beneficial for the subsequent synthesis of rhenium trioxide and rhenium dioxide.

[0010] The method for preparing rhenium trioxide and rhenium dioxide described above is characterized in that the drying temperature in step three is 100℃~160℃, and the drying time is 6h~10h. This invention, by controlling the drying temperature and time, ensures complete evaporation of moisture from the mixture of rhenium powder and perrhenic acid, while avoiding excessive temperature leading to rhenium volatilization loss.

[0011] The method for preparing rhenium trioxide and rhenium dioxide described above is characterized in that the inert atmosphere in step four is argon or nitrogen, and the thermal decomposition time is 2h~5h. This invention ensures that the products rhenium trioxide and rhenium dioxide are not re-oxidized by air by controlling the thermal decomposition of the rhenium oxide precursor under an argon or nitrogen atmosphere. Simultaneously, by controlling the thermal decomposition time, complete thermal decomposition is guaranteed, avoiding residual water of crystallization in the products.

[0012] Compared with the prior art, the present invention has the following advantages: 1. This invention obtains perrhenic acid solution and active rhenium powder by treating ammonium perrhenate with cation exchange resin and hydrogen reduction, respectively. The two are then mixed and dried to obtain a rhenium oxide precursor, which is then thermally decomposed to obtain cubic rhenium trioxide or orthorhombic rhenium dioxide solid. This not only avoids the hazards of using organic reagents and carbon monoxide in the preparation of rhenium trioxide, but also avoids the influence of monoclinic and orthorhombic mixed crystal forms on the performance of rhenium dioxide. This invention is applicable to the field of rhenium trioxide and rhenium dioxide synthesis technology.

[0013] 2. Unlike traditional methods for preparing rhenium trioxide that use volatile and hygroscopic rhenium heptaoxide solid as raw material, this invention converts ammonium perrhenate into perrhenic acid solution through an ion exchange reaction. The raw material perrhenic acid is easier to collect, obtain, and store than rhenium heptaoxide, reducing the difficulty of the preparation process and making it suitable for large-scale production.

[0014] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0015] Figure 1 The image shows the XRD pattern of the rhenium trioxide solid prepared in Example 1 of this invention.

[0016] Figure 2 This is a microscopic morphology diagram of the rhenium trioxide solid prepared in Example 1 of the present invention.

[0017] Figure 3 This is the energy dispersive spectroscopy (EDS) analysis diagram of the rhenium trioxide solid prepared in Example 1 of the present invention.

[0018] Figure 4 The image shows the XRD pattern of the rhenium dioxide solid prepared in Example 4 of this invention.

[0019] Figure 5 This is a microscopic morphology diagram of the rhenium dioxide solid prepared in Example 4 of the present invention.

[0020] Figure 6 This is the energy dispersive spectroscopy (EDS) analysis diagram of the rhenium dioxide solid prepared in Example 4 of the present invention. Detailed Implementation

[0021] Example 1 This embodiment includes the following steps: Step 1: Dissolve 2.3g of ammonium perrhenate in 100mL of deionized water to prepare an ammonium perrhenate solution. Then, flow the ammonium perrhenate solution through a container of 10mL H₂ at a flow rate of 4 BVs / h. + An exchange column of type C160 cation exchange resin was used to obtain a perrhenic acid solution with a Re mass concentration of 16 g / L; Step 2: Ammonium perrhenate was reduced with hydrogen at 800℃ for 4 hours to obtain active rhenium powder with an average particle size of 23 μm. Step 3: Mix 100 mL of the perrhenic acid solution obtained in Step 1 with 0.25 g of the active rhenium powder obtained in Step 2 in a certain proportion and dry it in air at 160 °C for 6 h to obtain the rhenium oxide precursor; Step 4: The rhenium oxide precursor obtained in Step 3 is placed in an argon atmosphere and thermally decomposed at 400°C for 5 hours to obtain red rhenium trioxide solid.

[0022] XRD analysis was performed on the rhenium trioxide solid prepared in this embodiment, and the results are as follows: Figure 1 As shown, the obtained rhenium trioxide solid phase is cubic ReO3.

[0023] The rhenium trioxide solid prepared in this embodiment was subjected to microstructure and energy dispersive spectroscopy analysis, and the results are as follows: Figure 2 and Figure 3 As shown, the morphology of the rhenium trioxide solid is cubic, and the mass percentages of Re and O elements are 79.30% and 20.70%, respectively.

[0024] In summary, the product prepared in this embodiment is a cubic rhenium trioxide with high purity.

[0025] Example 2 This embodiment includes the following steps: Step 1: Dissolve 2.89g of ammonium perrhenate in 100mL of deionized water to prepare an ammonium perrhenate solution. Then, flow the ammonium perrhenate solution through a container containing 15mL of H2 at a flow rate of 2BVs / h. + An exchange column of type C160 cation exchange resin was used to obtain a perrhenic acid solution with a Re mass concentration of 20 g / L; Step 2: Ammonium perrhenate was reduced with hydrogen at 800℃ for 1 hour to obtain active rhenium powder with an average particle size of 10 μm. Step 3: Mix 100 mL of the perrhenic acid solution obtained in Step 1 with 0.33 g of the active rhenium powder obtained in Step 2 in a certain proportion and dry it in air at 120 °C for 8 h to obtain the rhenium oxide precursor; Step 4: The rhenium oxide precursor obtained in Step 3 is placed in a nitrogen atmosphere and thermally decomposed at 300°C for 2 hours to obtain red rhenium trioxide solid.

[0026] Upon testing, the rhenium trioxide solid phase prepared in this embodiment was found to be cubic ReO3.

[0027] Example 3 This embodiment includes the following steps: Step 1: Dissolve 4.32g of ammonium perrhenate in 100mL of deionized water to prepare an ammonium perrhenate solution. Then, flow the ammonium perrhenate solution through a container containing 20mL of H2 at a flow rate of 3BVs / h. + An exchange column of type C160 cation exchange resin was used to obtain a perrhenic acid solution with a Re mass concentration of 30 g / L; Step 2: Ammonium perrhenate was reduced with hydrogen at 900℃ for 3 hours to obtain active rhenium powder with an average particle size of 31 μm. Step 3: Mix 100 mL of the perrhenic acid solution obtained in Step 1 with 0.5 g of the active rhenium powder obtained in Step 2 in a certain proportion and dry it in air at 100 °C for 10 h to obtain the rhenium oxide precursor; Step 4: The rhenium oxide precursor obtained in Step 3 is placed in an argon atmosphere and thermally decomposed at 500°C for 3 hours to obtain red rhenium trioxide solid.

[0028] Upon testing, the rhenium trioxide solid phase prepared in this embodiment was found to be cubic ReO3.

[0029] Example 4 This embodiment includes the following steps: Step 1: Dissolve 5.05g of ammonium perrhenate in 100mL of deionized water to prepare an ammonium perrhenate solution. Then, flow the ammonium perrhenate solution through a container containing 20mL of H2 at a flow rate of 2BVs / h. + A perrhenic acid solution with a Re mass concentration of 35 g / L was obtained by using a C160 cation exchange column. Step 2: Ammonium perrhenate was reduced with hydrogen at 1000℃ for 1 hour to obtain active rhenium powder with an average particle size of 50 μm. Step 3: Mix 100 mL of the perrhenic acid solution obtained in Step 1 with 1 g of the active rhenium powder obtained in Step 2 in a certain proportion and dry it in air at 100 °C for 10 h to obtain the rhenium oxide precursor; Step 4: Place the rhenium oxide precursor obtained in Step 3 under a nitrogen atmosphere and thermally decompose it at 600°C for 2 hours to obtain brownish-black rhenium dioxide solid.

[0030] XRD analysis was performed on the rhenium dioxide solid prepared in this embodiment, and the results are as follows: Figure 4 As shown, the obtained rhenium dioxide solid phase is orthorhombic ReO2.

[0031] The rhenium dioxide solid prepared in this embodiment was subjected to microstructure and energy dispersive spectroscopy analysis, and the results are as follows: Figure 5 and Figure 6 As shown, the morphology of the rhenium dioxide solid is irregular particles, and the mass percentages of Re and O elements are 85.67% and 14.33%, respectively.

[0032] In summary, the product prepared in this embodiment is rhenium dioxide with high purity in the orthorhombic form.

[0033] Example 5 This embodiment includes the following steps: Step 1: Dissolve 3.6g of ammonium perrhenate in 100mL of deionized water to prepare an ammonium perrhenate solution. Then, flow the ammonium perrhenate solution through a container of 10mL H₂ at a flow rate of 3BVs / h. + An exchange column of type C160 cation exchange resin was used to obtain a perrhenic acid solution with a Re mass concentration of 25 g / L; Step 2: Ammonium perrhenate was reduced with hydrogen at 900℃ for 4 hours to obtain active rhenium powder with an average particle size of 35μm. Step 3: Mix 100 mL of the perrhenic acid solution obtained in Step 1 with 0.42 g of the active rhenium powder obtained in Step 2 in a certain proportion and dry it in air at 140 °C for 6 h to obtain the rhenium oxide precursor; Step 4: The rhenium oxide precursor obtained in Step 3 is placed in a nitrogen atmosphere and thermally decomposed at 800°C for 5 hours to obtain brownish-black rhenium dioxide solid.

[0034] Testing revealed that the rhenium dioxide solid phase prepared in this embodiment is orthorhombic ReO2.

[0035] Example 6 This embodiment includes the following steps: Step 1: Dissolve 2.6g of ammonium perrhenate in 100mL of deionized water to prepare an ammonium perrhenate solution. Then, flow the ammonium perrhenate solution through a container containing 15mL of H2 at a flow rate of 4BVs / h. + An exchange column of type C160 cation exchange resin was used to obtain a perrhenic acid solution with a Re mass concentration of 18 g / L; Step 2: Ammonium perrhenate was reduced with hydrogen at 800℃ for 3 hours to obtain active rhenium powder with an average particle size of 20μm. Step 3: Mix 100 mL of the perrhenic acid solution obtained in Step 1 with 0.3 g of the active rhenium powder obtained in Step 2 in a certain proportion and dry in air at 160 °C for 8 h to obtain the rhenium oxide precursor; Step 4: The rhenium oxide precursor obtained in Step 3 is placed in an argon atmosphere and thermally decomposed at 700°C for 4 hours to obtain brownish-black rhenium dioxide solid.

[0036] Upon testing, the rhenium dioxide solid phase prepared in this embodiment was determined to be orthorhombic ReO2.

[0037] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any way. Any simple modifications, alterations, and equivalent changes made to the above embodiments based on the inventive essence shall still fall within the protection scope of the present invention.

Claims

1. A method for preparing rhenium trioxide and rhenium dioxide, characterized in that, The method includes the following steps: Step 1: Dissolve ammonium perrhenate in deionized water to prepare an ammonium perrhenate solution, then flow the ammonium perrhenate solution through a container filled with H... + An exchange column of type C160 cation exchange resin was used to obtain a perrhenic acid solution; the mass concentration of rhenium in the perrhenic acid solution was 16 g / L to 35 g / L. Step 2: Ammonium perrhenate is reduced with hydrogen to obtain activated rhenium powder; the average particle size of the activated rhenium powder is 10μm~50μm; Step 3: Mix the perrhenic acid solution obtained in Step 1 with the active rhenium powder obtained in Step 2 in a certain proportion and dry it in an air atmosphere to obtain the rhenium oxide precursor; the volume ratio of the perrhenic acid solution to the mass ratio of the active rhenium powder is 100mL~400mL:1g. Step 4: The rhenium oxide precursor obtained in Step 3 is thermally decomposed under an inert atmosphere to obtain rhenium trioxide or rhenium dioxide solid; when the thermal decomposition temperature is 300℃~500℃, rhenium trioxide solid is obtained, and when the thermal decomposition temperature is 600℃~800℃, rhenium dioxide solid is obtained.

2. The method for preparing rhenium trioxide and rhenium dioxide according to claim 1, characterized in that, The ammonium perrhenate solution described in step one flows through a container filled with H + The flow rate of the C160 cation exchange column is 2 BVs / h to 4 BVs / h, and the ammonium perrhenate solution reacts with H... + The volume ratio of type C160 cationic resin is 5:1 to 10:

1.

3. The method for preparing rhenium trioxide and rhenium dioxide according to claim 1, characterized in that, The hydrogen reduction in step two is carried out at a temperature of 800℃~1000℃ for 1h~4h.

4. The method for preparing rhenium trioxide and rhenium dioxide according to claim 1, characterized in that, The drying temperature in step three is 100℃~160℃, and the drying time is 6h~10h.

5. The method for preparing rhenium trioxide and rhenium dioxide according to claim 1, characterized in that, The inert atmosphere mentioned in step four is argon or nitrogen, and the thermal decomposition time is 2h to 5h.

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