A structured catalyst for trace fluorination reactions, its preparation method and use

Abstract

The application belongs to the field of fluorination reaction catalyst preparation, and relates to a structural catalyst for trace fluorination reaction and a preparation method and application thereof. The structural catalyst is composed of a substrate material, an adsorption material grown on the surface and a catalytic material compounded on the adsorption material, wherein the substrate material accounts for 50-90% of the mass percentage of the structural catalyst; the preparation method comprises the following steps: preparing a mother liquor of the adsorption material, then immersing the substrate material in the mother liquor of the adsorption material, then performing high-pressure treatment and calcination to obtain a structural catalyst precursor, and finally performing impregnation, high-pressure treatment, calcination, impregnation and calcination to realize the compound growth of the adsorption material and the catalytic material on the substrate; the structural catalyst can be applied to improve the conversion rate of raw materials or remove trace impurities, has the advantages of large specific surface area, excellent corrosion resistance, anti-pulverization, thermal conductivity and adsorption, and has a long service life, which is beneficial to continuous industrial production and reduces the cost of industrial production.

Description

Technical Field

[0001] This application belongs to the field of fluorination reaction catalyst preparation, and relates to a structural catalyst for fluorination reaction, specifically a structural catalyst for trace fluorination reaction, its preparation method and application. Background Technology

[0002] High-purity octafluoropropane has advantages such as low edge lateral erosion, high etching rate, and high precision in certain processes of etching ultra-high-performance integrated circuits and cleaning CVD chambers, which can well meet the requirements of low linewidth.

[0003] Currently, there are three processes for preparing octafluoropropane. One is the production of octafluoropropane as a byproduct of tetrafluoroethylene and hexafluoropropylene. This method yields octafluoropropane with many impurities, making purification difficult. Another method involves high-temperature cracking of trifluoromethane, hexafluoropropane, or heptafluoropropane. This method has low yield and complex impurities, making it unsuitable for industrial production. The last method involves the direct reaction of heptafluoropropane or hexafluoropropane with fluorine gas for fluorination. This reaction process is simple, the conditions are mild, and the yield is high. However, hexafluoropropane or heptafluoropropane cannot react completely, resulting in trace amounts of hexafluoropropane or heptafluoropropane in the product, which increases the difficulty of purification. This method is currently the mainstream method in the market. Therefore, the removal of trace amounts of hexafluoropropane or heptafluoropropane from the product is particularly important.

[0004] The reaction of hexafluoropropylene or heptafluoropropane with fluorine is a gas-to-gas reaction at room temperature, in which fluorine is in slight excess and the reaction is incomplete. Therefore, it is necessary to design a reaction so that the slight excess fluorine continues to react with the trace amount of hexafluoropropylene or heptafluoropropane after the reaction, thereby increasing the reaction depth of the raw material hexafluoropropylene or heptafluoropropane. This allows the crude octafluoropropane to be easily purified to obtain high-purity octafluoropropane for circuit applications.

[0005] Currently, the main technology for trace reaction is catalytic reaction technology. However, existing adsorbent-supported catalysts have problems such as the adsorbent material being susceptible to fluorine gas corrosion, and metal fluoride catalysts have problems such as small specific surface area, poor adsorption effect, and difficulty in molding. Summary of the Invention

[0006] To address the technical problems in the aforementioned related technologies, this application provides a structural catalyst for trace fluorination reactions, its preparation method, and its application. This aims to solve the technical problem of incomplete reaction between hexafluoropropylene or heptafluoropropane and fluorine gas, resulting in trace amounts of reactants in the products. The catalyst is designed to remove difficult-to-separate impurities and reduce purification difficulty.

[0007] In a first aspect, this application provides a structural catalyst for trace fluorination reactions, employing the following technical solution:

[0008] A structural catalyst for trace fluorination reactions, the structural catalyst comprising a substrate material, an adsorbent material grown on the surface, and a catalytic material composited with the adsorbent material, wherein the substrate material accounts for 50-90% of the mass percentage of the structural catalyst, and the adsorbent material and catalytic material grown on the surface account for 10-90% of the mass percentage of the structural catalyst.

[0009] In one specific implementation scheme, the substrate material is one of wire mesh corrugated plate, perforated plate corrugated plate, or Pall ring, and the substrate material is one of nickel, Monel, or Hastelloy.

[0010] Secondly, this application provides a method for preparing a structural catalyst for trace fluorination reactions, employing the following technical solution:

[0011] A method for preparing a structural catalyst for trace fluorination reactions includes the following steps: first, pre-preparing a mother liquor of adsorbent material; then, immersing a substrate material in the mother liquor of adsorbent material; then, subjecting the substrate to high-pressure treatment and calcination to obtain a structural catalyst matrix; and finally, achieving composite growth of adsorbent material and catalyst material on a substrate through impregnation, high-pressure treatment, calcination, impregnation, and calcination.

[0012] In one specific implementation, the mother liquor of the adsorbent material is a mixture of petroleum coke and asphalt in a mass ratio of 2 to 3:1.

[0013] In one specific implementation, the high-pressure treatment includes placing the substrate material impregnated with the mother liquor in an inert gas at 5–10 MPa for 2–24 hours.

[0014] In one specific implementation, the calcination temperature is 1150–1350°C, the time is 2–12 h, and the matrix of the structural catalyst is obtained under inert gas protection.

[0015] In one specific feasible implementation, the composite growth of the adsorbent material and the catalytic material on the substrate is accomplished by the following steps:

[0016] First, the phenolic resin is dissolved in alcohol and completely impregnated into the substrate. Then, it is left to stand in an inert gas at 5-10 MPa for 2-24 hours and calcined at 500-800℃ for 2-10 hours under inert gas protection.

[0017] Subsequently, the calcined parent material is impregnated with a saturated aqueous solution of one or more of magnesium sulfate, nickel sulfate, and chromium sulfate, dried, and then calcined at 1000–1200°C for 0.5–1 h under inert gas protection to complete the composite growth of the adsorbent and catalytic materials on the substrate, thereby obtaining the structured catalyst.

[0018] Thirdly, this application provides an application of a structural catalyst for trace fluorination reactions, employing the following technical solution:

[0019] Application of a structural catalyst for trace fluorination reactions, used to catalyze the fluorination reaction of trace hexafluoropropylene or heptafluoropropane with trace amounts of fluorine gas, to improve feed conversion or remove trace impurities.

[0020] In one specific feasible implementation, the concentration of trace hexafluoropropylene or heptafluoropropane is 0.001% to 2%, and the reaction temperature is 100 to 200°C.

[0021] This application includes at least one of the following beneficial technical effects:

[0022] 1. The structural catalyst provided in this application uses a metallic material as a base, with petroleum coke and pitch as carbon materials, which are subjected to high-pressure pressing and calcination. It exhibits high structural strength and a large specific surface area, resulting in excellent corrosion resistance, anti-pulverization properties, thermal conductivity, and adsorption capacity. In the field of trace fluorination, it demonstrates superior catalytic performance. It also boasts a long service life, which is beneficial for continuous industrial production. Furthermore, the adsorption materials used in this application are abundant and have low raw material costs. The catalytic reaction temperature is low, energy consumption is low, and safety is high, significantly reducing the cost of industrial production and demonstrating substantial economic benefits and promising development prospects.

[0023] 2. This application utilizes asphalt and petroleum coke as carbon-based materials, combined with alcohol to dissolve phenolic resin to form an adsorbent material, which has a large specific surface area and relies on van der Waals forces to physically adsorb trace impurities. The adsorbed impurities are removed by reacting with fluorine gas catalyzed by a catalyst (metal fluoride: metal sulfate decomposes to metal oxide upon heating, and the metal oxide is fluorinated in fluorine gas to form metal fluoride) grown in the adsorbent material. The metal coordination unsaturation in the metal fluoride creates defect sites, giving it high Lewis acidity and exhibiting high catalytic activity, thus achieving efficient adsorption and separation. Detailed Implementation

[0024] The present application will be further described in detail below with reference to specific embodiments.

[0025] Example 1

[0026] This application discloses a method for preparing a structural catalyst for trace fluorination reactions, comprising the following steps:

[0027] First, petroleum coke and asphalt are mixed at a mass ratio of 2:1 to prepare the adsorbent mother liquor. Hastelloy Pall rings are selected as the base material of the structural catalyst, accounting for 90% of the mass of the structural catalyst. The Pall rings are immersed in the mixed adsorbent mother liquor, left to stand for 1 hour, and then subjected to high pressure treatment, specifically, left to stand for 24 hours under an inert gas pressure of 10 MPa. The high-pressure treated Pall rings are then removed and calcined at 1150℃ for 2 hours under inert gas protection to obtain the structural catalyst mother liquor.

[0028] The precursor catalyst was impregnated with phenolic resin dissolved in alcohol at a mass ratio of 1:3. It was then allowed to stand for 24 hours under an inert gas atmosphere of 10 MPa, followed by calcination at 800°C for 2 hours under inert gas protection. In this case, the alcohol-dissolved phenolic resin served as the adsorbent material, composited onto the substrate. Next, the calcined precursor was impregnated with a saturated nickel sulfate aqueous solution, dried, and then calcined at 1000°C for 0.5 hours under inert gas protection to obtain structural catalyst 1. In this case, the saturated nickel sulfate aqueous solution served as the catalytic material, composited onto the substrate. The adsorbent and catalytic materials in structural catalyst 1 comprised 10% of the total mass.

[0029] Trace hexafluoropropylene with trace amounts of fluorine gas at a concentration of 2% was fluorinated using structural catalyst 1 at 200°C. GC analysis showed that the content of hexafluoropropylene in the tail gas was 0.002%, and the removal efficiency of hexafluoropropylene was 99.9%.

[0030] It should be noted that the embodiments in this application are merely examples. For instance, the catalyst material can be one or more saturated aqueous solutions of magnesium sulfate, nickel sulfate, and chromium sulfate; in this embodiment, a saturated nickel sulfate aqueous solution is selected. The substrate material can be one of a wire mesh corrugated plate, a perforated plate corrugated plate, or a Pall ring; in this embodiment, a Pall ring is selected. The substrate material can be one of nickel, Monel, or Hastelloy; in this embodiment, Hastelloy is selected. The inert gas in the above method is a gas that does not participate in the reaction and is inert, such as nitrogen or helium.

[0031] Example 2

[0032] This application discloses a method for preparing a structural catalyst for trace fluorination reactions, comprising the following steps:

[0033] First, petroleum coke and asphalt were mixed at a mass ratio of 2.5:1 to prepare the adsorbent mother liquor. A perforated corrugated plate made of Monel material was selected as the base material of the structural catalyst, accounting for 70% of the mass of the structural catalyst. The perforated corrugated plate was immersed in the mixed adsorbent mother liquor, and after standing for 1 hour, it was subjected to high pressure treatment, specifically standing for 12 hours under an inert gas pressure of 7 MPa. The high-pressure treated Pall rings were then removed and calcined at 1200℃ for 6 hours under inert gas protection to obtain the structural catalyst mother body.

[0034] The phenolic resin matrix was impregnated with alcohol at a mass ratio of 1:3. The mixture was allowed to stand for 12 hours under an inert gas pressure of 7 MPa, and then calcined at 650°C for 5 hours under an inert gas protection. The calcined matrix was then impregnated with a saturated chromium sulfate aqueous solution, dried, and calcined at 1100°C for 0.7 hours under an inert gas protection to obtain structural catalyst 2. The adsorbent and catalytic materials account for 30% of the total mass of structural catalyst 2.

[0035] Trace heptafluoropropane at a concentration of 0.15% was catalyzed by structural catalyst 2 and fluorinated with trace amounts of fluorine at 150°C for fluorination. GC analysis showed that the heptafluoropropane content in the tail gas was 0.0009%, and the heptafluoropropane removal efficiency was 99.4%.

[0036] Example 3

[0037] This application discloses a method for preparing a structural catalyst for trace fluorination reactions, comprising the following steps:

[0038] First, petroleum coke and asphalt are mixed at a mass ratio of 3:1 to prepare the adsorbent mother liquor. Nickel-plated wire mesh corrugated plates are selected as the base material for the structural catalyst, accounting for 50% of the mass of the structural catalyst. The perforated corrugated plates are immersed in the mixed adsorbent mother liquor, left to stand for 1 hour, and then subjected to high pressure treatment. Specifically, the plates are left to stand for 2 hours under an inert gas pressure of 5 MPa. The high-pressure treated Pall rings are then removed and calcined at 1350℃ for 12 hours under inert gas protection to obtain the structural catalyst mother body.

[0039] The phenolic resin matrix was impregnated with alcohol at a mass ratio of 1:3. The mixture was allowed to stand for 2 hours under an inert gas pressure of 5 MPa, and then calcined at 500°C for 10 hours under inert gas protection. The calcined matrix was then impregnated with a 20 wt% aqueous solution of nickel sulfate, magnesium sulfate, and chromium sulfate at a mass ratio of 1:1:1. After drying, the matrix was calcined at 1200°C for 1 hour under inert gas protection to obtain structural catalyst 3. In structural catalyst 3, the adsorbent and catalytic materials account for 50% of the total mass.

[0040] Trace hexafluoropropylene with trace amounts of fluorine gas at a concentration of 0.001% was fluorinated using structural catalyst 3 at 100°C. GC analysis showed that the content of hexafluoropropylene in the tail gas was 0.00001%, and the removal efficiency of hexafluoropropylene was 99%.

[0041] Although the present invention has been described in detail by way of preferred embodiments, the present invention is not limited thereto. Various equivalent modifications or substitutions can be made to the embodiments of the present invention by those skilled in the art without departing from the spirit and essence of the invention, and such modifications or substitutions should all be within the scope of the present invention. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should also be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be determined by the scope of the claims.

Claims

1. A structural catalyst for trace fluorination reactions, characterized in that, The structural catalyst is composed of a substrate material, an adsorbent material grown on the surface, and a catalytic material composited with the adsorbent material, wherein the substrate material accounts for 50-90% of the mass percentage of the structural catalyst, and the adsorbent material and catalytic material grown on the surface account for 10-90% of the mass percentage of the structural catalyst. The substrate material is one of wire mesh corrugated plate, perforated plate corrugated plate, and Pall ring, and the material of the substrate material is one of nickel, Monel, and Hastelloy. The adsorbent material uses a mixture of petroleum coke and asphalt as the mother liquor. The substrate material is immersed in the mother liquor and then subjected to high pressure treatment and high temperature calcination to obtain the structural catalyst matrix. It is then impregnated with phenolic resin dissolved in alcohol, subjected to high pressure treatment, and high temperature calcination to obtain the final product. The catalytic material is impregnated and calcined with one or more saturated aqueous solutions of magnesium sulfate, nickel sulfate, and chromium sulfate, and then composited onto the adsorbent material.

2. The method for preparing a structural catalyst for trace fluorination reactions according to claim 1, characterized in that: Includes the following steps: First, a mixture of petroleum coke and asphalt at a mass ratio of 2-3:1 is prepared as the mother liquor for the adsorbent material. Then, the substrate material is immersed in the mother liquor of the adsorbent material, followed by high-pressure treatment and calcination to obtain the structural catalyst matrix. Finally, the adsorbent material and the catalyst material are compositely grown on the substrate by alcohol dissolution, phenolic resin impregnation, high-pressure treatment under inert gas protection, calcination under inert gas protection, impregnation with one or more saturated aqueous solutions of magnesium sulfate, nickel sulfate, and chromium sulfate, and calcination.

3. The method for preparing a structural catalyst for trace fluorination reactions according to claim 2, characterized in that: The high-pressure treatment includes placing the substrate material impregnated with the mother liquor in an inert gas at 5-10 MPa for 2-24 hours.

4. The method for preparing a structural catalyst for trace fluorination reactions according to claim 2, characterized in that: In the preparation of the structural catalyst matrix, the calcination temperature is 1150–1350 °C, the time is 2–12 h, and the structural catalyst matrix is ​​obtained under inert gas protection.

5. The method for preparing a structural catalyst for trace fluorination reactions according to claim 2, characterized in that: The composite growth of adsorbent and catalytic materials on the substrate is accomplished through the following steps: First, the phenolic resin is dissolved in alcohol and completely impregnated into the substrate. Then, it is left to stand in an inert gas at 5-10 MPa for 2-24 hours and calcined at 500-800℃ for 2-10 hours under inert gas protection. Subsequently, the calcined parent material is impregnated with a saturated aqueous solution of one or more of magnesium sulfate, nickel sulfate, and chromium sulfate, dried, and then calcined at 1000–1200°C for 0.5–1 h under inert gas protection to complete the composite growth of the adsorbent and catalytic materials on the substrate, thereby obtaining the structured catalyst.

6. The application of the structural catalyst of claim 1 for trace fluorination reactions, characterized in that: It is used to catalyze the fluorination reaction of trace amounts of hexafluoropropylene or heptafluoropropane with trace amounts of fluorine gas, and to improve the conversion rate of raw materials or remove trace impurities.

7. The application of the structural catalyst for trace fluorination reactions according to claim 6, characterized in that: The concentration of trace hexafluoropropylene or heptafluoropropane is 0.001% to 2%, and the reaction temperature is 100 to 200°C.