Synthesis method of dichloromolybdenum dioxide

Abstract

The invention belongs to the field of synthesis of molybdenum dioxide dichloride, and particularly relates to a synthesis method of molybdenum dioxide dichloride. Comprising the following steps: S1, pretreating a molybdenite raw material; s2, the pretreated molybdenite raw material is placed in a reactor, chlorine trifluoride, oxygen, fluorine mixed gas and inert gas are introduced into the reactor and react with the pretreated molybdenite raw material at the reaction temperature of 20-50 DEG C, and a crude product of dichloromolybdenum dioxide and a crude product of sulfur tetrafluoride are generated; and collecting a dichloromolybdenum dioxide crude product from the bottom of the reactor. The raw ore molybdenite is used as the molybdenum raw material, the cost of the synthesis process is reduced, the process route is simple, and the reaction conditions are milder; in addition, the byproduct sulfur tetrafluoride in the invention is a product with high added value.

Description

A method for synthesizing molybdenum dichlorodioxide Technical Field

[0001] This application belongs to the field of synthesis of molybdenum dichlorodioxide, specifically relating to a method for synthesizing molybdenum dichlorodioxide. Background Technology

[0002] Molybdenum dioxide (Mo₂CO₃) is an important inorganic molybdenum oxyhalide compound, typically occurring as yellow to orange crystalline or powdery solids. This compound exhibits good solubility in polar solvents but low solubility in nonpolar solvents. Due to its unique electronic structure and reactivity, Mo₂CO₃ is primarily used in two areas: First, in catalysis, it is a highly efficient and multifunctional catalyst or catalyst precursor. In organic synthesis, it is widely used in various redox reactions, such as the oxidation of olefins, the reduction of carbonyl compounds, and the space- and space-selective hydrogenation of olefins. Furthermore, it can efficiently catalyze the thioacetalization of heterocyclic, aromatic, and aliphatic compounds, as well as the reaction of alcohols with isocyanates to form mono- or polycarbamates.

[0003] Secondly, in the field of materials science, its high volatility and good thermal stability make it an ideal precursor material for preparing high-performance molybdenum oxide thin films using plasma-enhanced chemical vapor deposition or atomic layer deposition techniques. These films have broad application prospects in semiconductor devices, optical coatings, and sensors. Meanwhile, molybdenum dioxide dichlorodioxide is also a starting material for synthesizing Schrock-type highly reactive alkylene molybdenum complexes, which play an important role in olefin metathesis reactions.

[0004] The existing technologies for preparing molybdenum dichloride mainly include the following routes: ① The reaction of molybdenum trioxide with chlorine gas involves mixing molybdenum trioxide (MoO3) with activated carbon, placing it in a reaction tube, replacing the air with an inert gas, then introducing dry chlorine gas and heating to prepare molybdenum dichloride; for example, the technical solution disclosed in CN117208963B discloses a novel method for preparing molybdenum dichloride, in which molybdenum trichloride and activated carbon are mixed in a certain proportion, placed in a tubular reactor and heated to a certain temperature, and then an excess of dry chlorine gas is introduced to react and obtain molybdenum dichloride gas; the raw materials for this method are relatively easy to obtain, but the reaction process requires precise control of the chlorine gas flow rate and temperature gradient to collect the sublimation products, making the operation relatively cumbersome, and the use of activated carbon may introduce impurities. ② This involves the reaction of molybdenum trichloride with oxygen. Oxygen is introduced into an aqueous solution of molybdenum trichloride (MoCl3), resulting in the formation of molybdenum dioxide (MoCl3). However, this method involves an aqueous system, and MoCl3 is extremely sensitive to water and readily hydrolyzes. Therefore, the control of reaction conditions is extremely critical, product separation and purification are difficult, and yield and purity are often hard to guarantee, making it unsuitable for downstream applications sensitive to moisture. ③ This involves the reaction of ammonium molybdate with ammonium chloride. Ammonium molybdate and ammonium chloride are mixed in a certain proportion, dissolved in water, and heated in a closed container. After the reaction is complete, the mixture is cooled, filtered, washed, and dried to obtain MoCl3. This route avoids the direct use of chlorine gas, improving safety. However, the reaction usually needs to be carried out at a high temperature, and the byproducts are complex, requiring multiple post-processing steps. The purity of the product may be affected by the decomposition products of ammonium salts. ④ is the molybdenum pentachloride oxidation method, which involves heating molybdenum pentachloride (MoCl5) in air to react with oxygen to produce molybdenum dichlorodioxide. For example, the technical solution disclosed in announcement number CN118954594A provides a method for preparing high-purity molybdenum dichlorodioxide. High-purity molybdenum pentachloride raw material is placed in a tubular reactor, protected by argon gas, heated to 200-400℃, the argon gas is turned off, and oxygen is introduced into the tubular reactor. After reacting for 4-6 hours, molybdenum dichlorodioxide gas and molybdenum pentachloride gas are obtained. However, molybdenum pentachloride itself is expensive, and this method involves releasing chlorine gas simultaneously, requiring high corrosion resistance of equipment and a robust exhaust gas treatment system, resulting in poor economic efficiency and safety. ⑤ is the molybdenum dioxide chlorination method, which involves reacting molybdenum dioxide (MoO2) with chlorine gas at high temperatures to produce molybdenum dichlorodioxide. However, the chlorination of molybdenum dioxide is a strongly endothermic reaction, requiring a high-temperature environment and consuming a large amount of energy.

[0005] In addition, there are other novel preparation methods. For example, the technical solution disclosed in announcement number TW202530136A discloses a method for producing molybdenum dichlorodioxide. This method involves mixing anhydrous molybdenum trioxide with thionyl chloride in a non-coordinated solvent under inert gas conditions, and then refluxing and stirring the mixture at high temperature to produce a precipitated solid product, molybdenum dichlorodioxide. However, this method involves highly toxic reagents, complex waste treatment, and reliance on organic solvents, leading to a complex process and increased risks.

[0006] The technical solution disclosed in CN119551724A is a method and apparatus for preparing molybdenum dichlorodioxide. The method involves introducing oxygen and hydrogen chloride into a reactor at a temperature of 180–600°C, reacting for 0.5–3 hours to obtain molybdenum dichlorodioxide. However, this method suffers from several drawbacks, including extremely high raw material costs, increased energy consumption and equipment investment due to the high reaction temperature, and difficulties in product separation and obtaining high-purity MoO2Cl2 due to the formation of a mixture of molybdenum chloride oxides at high temperatures.

[0007] The technical solution disclosed in CN119774661B is a method for preparing molybdenum dichlorodioxide based on a molybdenum-containing solution. The method involves adding a pH adjuster to the molybdenum-containing solution to adjust the pH to 7.5-9.0, obtaining a treated molybdenum-containing solution; adding a calcium source to the treated molybdenum-containing solution and stirring at 30-60℃ for 30-100 min, followed by solid-liquid separation to obtain a molybdenum-containing precipitate; mixing the molybdenum-containing precipitate with a chlorinating agent to obtain a chlorination reactant; introducing a protective atmosphere into the chlorination reactant and reacting at 150-180℃ for 1-3 h to obtain molybdenum dichlorodioxide gas; and then condensing the molybdenum dichlorodioxide gas at 0-50℃ to obtain molybdenum dichlorodioxide based on the molybdenum-containing solution. However, this method suffers from a lengthy and complex process, high equipment investment, unsuitability for continuous production, large waste generation, and high subsequent treatment costs. In summary, while there are multiple pathways for the preparation of molybdenum dichlorodioxide (MoD2O2), they are all constrained to varying degrees by issues such as high raw material costs, enormous reaction energy consumption, complex and lengthy process flows, significant safety risks, and the difficulty in balancing product purity with large-scale production. Especially with the expanding application of MoD2O2 in high-end semiconductor PECVD / ALD thin film deposition, the market demand for low-cost, high-purity, high-performance, and stable-supply MoD2O2 precursors is becoming increasingly urgent. Therefore, there is an urgent need to develop a method for synthesizing MoD2O2 with readily available raw materials, mild reaction conditions, and a simple process flow. Summary of the Invention

[0008] Existing technologies for preparing molybdenum dichlorodioxide are constrained to varying degrees by high raw material costs, enormous reaction energy consumption, complex and lengthy process flows, significant safety risks, and the difficulty in balancing product purity with large-scale production. This application proposes a method for synthesizing molybdenum dichlorodioxide, comprising the following steps: Step S1. Pre-treating molybdenite raw material; Step S2. Placing the pre-treated molybdenite raw material in a reactor, and introducing a mixture of chlorine trifluoride, oxygen, fluorine gas, and a protective gas into the reactor, reacting with the pre-treated molybdenite raw material at a reaction temperature of 20-50°C to produce crude molybdenum dichlorodioxide and crude sulfur tetrafluoride; collecting the crude molybdenum dichlorodioxide from the bottom of the reactor.

[0009] The reaction equation is: MoS2+2ClF3+O2+F2→MoO2Cl2+2SF4; preferably, in step S1, the pretreatment method of molybdenite raw material is to crush it to a particle size of 5~30mm.

[0010] Preferably, step S2 further includes pre-treating the reactor containing pretreated molybdenite raw material. The pre-treating process involves heating the reactor containing the pretreated molybdenite raw material to 100-150°C and evacuating it to a pressure below -0.09 MPa for 2 hours.

[0011] Preferably, in step S2, the molar ratio of chlorine trifluoride, fluorine gas, and oxygen is 2:1:1; and the volume ratio of the mixture of chlorine trifluoride, fluorine gas, and oxygen gas to the inert gas is 1:4 to 1:20.

[0012] Preferably, the protective gas is selected from any one or more of nitrogen, argon, and helium.

[0013] Preferably, the synthesis method further includes step S3, where the crude sulfur tetrafluoride product exiting the reactor is collected through a cold trap.

[0014] Preferably, in step S3, the temperature of the cold trap is -90 to -45°C.

[0015] Preferably, the synthesis method further includes step S4. The uncondensed tail gas is passed into a two-stage alkaline scrubbing tower for treatment. The alkaline solution is an aqueous solution of sodium hydroxide, an aqueous solution of potassium hydroxide, or a mixture of two alkaline solutions in any mass ratio. The concentration of the alkaline solution is not less than 2 mol / L, and the operating temperature of the alkaline scrubbing tower is 0~70℃.

[0016] The beneficial effects of this application are as follows: This application uses natural molybdenite directly as raw material, avoiding the need for expensive intermediates such as high-purity molybdenum oxide, molybdic acid, or molybdenum metal required by traditional methods, thus significantly reducing raw material costs from the source. Simultaneously, the pretreatment only requires crushing and a one-step synthesis route, reducing equipment investment and operating units, making the overall process simple and low-cost.

[0017] The synthesis reaction in this application is carried out at 20-50°C, which significantly reduces energy consumption compared to the ambient high-temperature conditions in existing technologies. This not only reduces energy costs but also lowers the requirements for reactor materials and heating and cooling, making the production equipment simpler and requiring less investment.

[0018] This application controls the oxidative fluorination atmosphere of the reaction by controlling gas parameters, enabling efficient and selective conversion of molybdenite into the target product MoO2Cl2 at low temperatures. Simultaneously, it effectively suppresses side reactions such as over-fluorination or oxidation, improving reaction selectivity and main product yield. Pre-treatment with heating and vacuum effectively removes moisture and volatile impurities from the raw materials and system, further ensuring the smooth progress of the reaction and the initial purity of the product.

[0019] The mild reaction temperature in this application is itself an important safety factor, reducing the risk of material decomposition due to high temperatures. The use of inert gas dilution moderates the reaction process, avoiding violent exothermic reactions and making the reaction more stable and controllable. Furthermore, a product collection, byproduct recovery, and tail gas treatment unit is installed after the reaction, forming a closed loop and further ensuring production safety and environmental friendliness.

[0020] This application not only synthesizes the target product, but also converts the sulfur generated in the reaction into a high-value-added sulfur tetrafluoride byproduct, which has important applications in pharmaceutical intermediates and integrated circuits.

[0021] This application presents a complete process, from raw material pretreatment, reaction, main product collection and purification, by-product recovery to tail gas treatment.

[0022] In summary, this application provides a method for synthesizing molybdenum dioxide dichlorodioxide that is low in cost, mild in conditions, safe and controllable, allows for comprehensive utilization of resources, and is easy to industrialize. Attached Figure Description

[0023] Figure 1 is a diagram of the apparatus for the synthesis of molybdenum dichlorodioxide according to this application. The figures are labeled as follows: 1. Reactor; 2. Cold trap; 3. Primary alkaline washing tower; 4. Secondary alkaline washing tower. Detailed Implementation

[0024] To further illustrate the technical means and effects adopted by this application in order to achieve the intended purpose of the invention, the following detailed description of the specific implementation methods, structures, features and effects of this application is provided in conjunction with the accompanying drawings and preferred embodiments.

[0025] This embodiment provides a synthesis apparatus for molybdenum dichlorodioxide, including a reactor 1, a cold trap 2, a primary alkaline washing tower 3, and a secondary alkaline washing tower 4. The outlet of the reactor 1 is connected to the inlet of the cold trap 2, the outlet of the cold trap 2 is connected to the inlet of the primary alkaline washing tower 3, and the outlet of the primary alkaline washing tower 3 is connected to the inlet of the secondary alkaline washing tower 4. The top of the secondary alkaline washing tower 4 is used for tail gas discharge; the bottom of the reactor 1 is used for powder collection.

[0026] The operating principle of the apparatus is as follows: Molybdenite, the raw material for molybdenum production, is pulverized and loaded into reactor 1. After pressure testing and leak detection, the reactor is heated and evacuated; after a period of time, the reactor is cooled. A mixture of chlorine trifluoride, oxygen, and fluorine, along with an inert gas, is introduced into reactor 1 to react with the molybdenite. Circulating water is circulated through the external jacket of the reactor to cool it and control the reactor temperature. After the reaction, solid molybdenum dioxide (Mo₂CO₃) is obtained at the bottom of reactor 1, and sulfur tetrafluoride (SF₂CO₃) gas, a byproduct, enters cold trap 2. The temperature of cold trap 2 is controlled, and the SF₂CO₃ product is collected. Other non-condensable gaseous impurities in cold trap 2 enter an alkaline scrubbing tower to remove fluorine-containing tail gas. The alkaline scrubbing tower consists of two stages: a primary alkaline scrubbing tower 3 and a secondary alkaline scrubbing tower 4. After two stages of treatment, the gas is vented.

[0027] Examples 1-3 and Comparative Examples 1-2 are based on the apparatus provided in the apparatus examples, and are as follows: Example 1 Step S1. Crush the molybdenum raw material molybdenite to 5mm.

[0028] Step S2. The crushed molybdenite is loaded into the reactor. After passing the pressure test and leak detection, the reactor is heated to 150°C and evacuated to below -0.09 MPa. After 2 hours, the reactor is cooled to room temperature. Chlorine trifluoride, oxygen, fluorine, and an inert gas are mixed and introduced into the reactor using a mass flow controller to react with the molybdenite. The ratio of the mixture of chlorine trifluoride, fluorine, and oxygen to the inert gas is 1:20; the inert gas is nitrogen. Circulating water is introduced into the outer jacket of the reactor to cool it down, and the reactor temperature is controlled at 20°C. After the reaction, solid molybdenum dioxide dichloride is obtained at the bottom of the reactor.

[0029] Step S3. The byproduct sulfur tetrafluoride gas enters the sulfur tetrafluoride cold trap after the reactor; the temperature of the sulfur tetrafluoride cold trap is controlled at -45℃, and the sulfur tetrafluoride product is collected. The purity of the crude molybdenum dichlorodioxide is 98.2%, and the purity of the crude sulfur tetrafluoride is 95.1%.

[0030] Step S4. Other non-condensable gas impurities in the sulfur tetrafluoride cold trap enter the alkaline scrubbing tower. The alkaline solution in the alkaline scrubbing tower is sodium hydroxide with a concentration of 2 mol / L. The temperature of the alkaline scrubbing tower is 70℃ to remove fluorine-containing tail gas. The alkaline scrubbing tower is a two-stage system. After two-stage treatment, the gas is vented.

[0031] Example 2, Step S1: Crush the molybdenum raw material molybdenite to 15mm.

[0032] Step S2. The crushed molybdenite is loaded into the reactor. After pressure testing and leak detection, the reactor is heated to 125°C and evacuated to below -0.09 MPa. After 2 hours, the reactor is cooled to room temperature. A mixture of chlorine trifluoride, oxygen, fluorine, and an inert gas is introduced into the reactor using a mass flow controller to react with the molybdenite. The ratio of the chlorine trifluoride, fluorine, and oxygen mixture to the inert gas is 1:10; the inert gas is argon. Circulating water is circulated through the reactor jacket for cooling, and the reactor temperature is controlled at 35°C. After the reaction, solid molybdenum dioxide dichloride is obtained at the bottom of the reactor.

[0033] Step S3. The byproduct sulfur tetrafluoride gas enters the sulfur tetrafluoride cold trap after the reactor; the temperature of the sulfur tetrafluoride cold trap is controlled at -70℃, and the sulfur tetrafluoride product is collected. The purity of the crude molybdenum dichlorodioxide is 98.5%, and the purity of the crude sulfur tetrafluoride is 94.8%.

[0034] Step S4. Other non-condensable gas impurities in the sulfur tetrafluoride cold trap enter the alkaline scrubbing tower. The alkaline solution in the alkaline scrubbing tower is potassium hydroxide with a concentration of 2 mol / L. The temperature of the alkaline scrubbing tower is 35℃ to remove fluorine-containing tail gas. The alkaline scrubbing tower is a two-stage system. After two-stage treatment, the gas is vented.

[0035] Example 3, Step S1: Crush the molybdenum raw material molybdenite to 30mm.

[0036] Step S2. The crushed molybdenite is loaded into the reactor. After passing the pressure test and leak detection, the reactor is heated to 100°C and evacuated to below -0.09 MPa. After 2 hours, the reactor is cooled to room temperature. A mixture of chlorine trifluoride, oxygen, fluorine, and an inert gas is introduced into the reactor using a mass flow controller to react with the molybdenite. The ratio of the chlorine trifluoride, fluorine, and oxygen mixture to the inert gas is 1:4; the inert gas is helium. Circulating water is introduced into the reactor jacket for cooling, and the reactor temperature is controlled at 50°C. After the reaction, solid molybdenum dioxide dichloride is obtained at the bottom of the reactor.

[0037] Step S3. The byproduct sulfur tetrafluoride gas enters the sulfur tetrafluoride cold trap after the reactor; the temperature of the sulfur tetrafluoride cold trap is controlled at -90℃, and the sulfur tetrafluoride product is collected. The purity of the crude molybdenum dichlorodioxide is 97.6%, and the purity of the crude sulfur tetrafluoride is 95.6%.

[0038] Step S4. Other non-condensable gas impurities in the sulfur tetrafluoride cold trap enter the alkaline scrubbing tower. The alkaline solution in the alkaline scrubbing tower is a mixture of potassium hydroxide and potassium hydroxide in a mass ratio of 1:1, with a concentration of 2 mol / L. The temperature of the alkaline scrubbing tower is 0℃ to remove fluorine-containing tail gas. The alkaline scrubbing tower is a two-stage system, and the gas is vented after the two-stage treatment.

[0039] Comparative Example 1 differs from Example 1 in that the reactor temperature was controlled at 0°C. The purity of the crude molybdenum dichlorodioxide was 90.2%, and the purity of the crude sulfur tetrafluoride was 89.4%.

[0040] The difference between Comparative Example 2 and Example 1 is that the reactor temperature was controlled at 100°C. The purity of the crude molybdenum dichlorodioxide was 88.7%, and the purity of the crude sulfur tetrafluoride was 89.3%.

[0041] The above description is merely a preferred embodiment of this application and is not intended to limit this application in any way. Although this application has been disclosed above with reference to preferred embodiments, it is not intended to limit this application. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the technical solution of this application. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of this application without departing from the scope of the technical solution of this application shall still fall within the scope of the technical solution of this application.

Claims

1. A method for synthesizing molybdenum dichlorodioxide, characterized in that, The process includes the following steps: Step S1. Pre-treating the molybdenite raw material; Step S2. Placing the pre-treated molybdenite raw material in a reactor, and introducing a mixture of chlorine trifluoride, oxygen, fluorine gas, and a protective gas into the reactor, reacting with the pre-treated molybdenite raw material at a reaction temperature of 20~50℃ to produce crude molybdenum dioxide dichloride and crude sulfur tetrafluoride; collecting the crude molybdenum dioxide dichloride from the bottom of the reactor.

2. The method for synthesizing molybdenum dichlorodioxide according to claim 1, characterized in that, In step S1, the pretreatment method for molybdenite raw material is to crush it to a particle size of 5~30mm.

3. The method for synthesizing molybdenum dichlorodioxide according to claim 1, characterized in that, In step S2, the reactor containing the pretreated molybdenite raw material is further pretreated. The pretreatment involves heating the reactor containing the pretreated molybdenite raw material to 100-150°C and evacuating it to a pressure below -0.09 MPa for 2 hours.

4. The method for synthesizing molybdenum dichlorodioxide according to claim 1, characterized in that, In step S2, the molar ratio of chlorine trifluoride, fluorine gas, and oxygen is 2:1:1; the volume ratio of the mixture of chlorine trifluoride, fluorine gas, and oxygen gas to the inert gas is 1:4 to 1:

20.

5. The method for synthesizing molybdenum dichlorodioxide according to claim 1, characterized in that, The protective gas is any one or more of nitrogen, argon, and helium.

6. The method for synthesizing molybdenum dichlorodioxide according to claim 1, characterized in that, The synthesis method further includes step S3, in which crude sulfur tetrafluoride from the reactor is collected through a cold trap.

7. The method for synthesizing molybdenum dichlorodioxide according to claim 6, characterized in that, In step S3, the temperature of the cold trap is -90~-45℃.

8. The method for synthesizing molybdenum dichlorodioxide according to claim 1, characterized in that, The synthesis method further includes step S4, in which the uncondensed tail gas is passed into a two-stage alkaline scrubbing tower for treatment, wherein the operating temperature of the alkaline scrubbing tower is 0~70℃.

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