Core-shell type catalyst as well as preparation method and application thereof

Abstract

The invention provides a core-shell type catalyst and a preparation method thereof, and also provides a method for preparing chlorine by performing hydrogen chloride catalytic oxidation in the presence of a fluorine-containing compound by using the core-shell type catalyst, the catalyst has a core-shell structure, and comprises: a core located inside, the core comprising nickel oxide or titanium oxide; the active layer comprises oxides of one or more of the following elements: ruthenium, rhodium, palladium, copper, nickel, molybdenum and rare earth elements; a coating layer that contains titanium oxide when the core contains nickel oxide; and when the core contains titanium oxide, the cladding layer contains nickel oxide. The catalyst does not contain toxic components, the preparation method is simple, and the catalyst is high in activity, good in fluoride tolerance and high in stability.

Description

Technical Field

[0001] This application relates to the field of catalysis, and more specifically to a core-shell catalyst and its preparation method. It also provides a method for using the core-shell catalyst to catalytically oxidize hydrogen chloride to produce chlorine gas in the presence of fluorine-containing compounds. Background Technology

[0002] Chlorine is an important basic chemical raw material, widely used in chemistry, metallurgy, medicine, and materials synthesis. However, chlorine production generates hydrogen chloride as a byproduct during use; for example, a large amount of hydrogen chloride is produced during the phosgene process for producing MDI and TDI. With the increasing demand for chlorine, the amount of hydrogen chloride as a byproduct is also increasing. Since hydrogen chloride is inexpensive and industrial demand is small, achieving high-value utilization of hydrogen chloride is particularly important. The reaction process for converting hydrogen chloride into chlorine using catalytic oxidation is illustrated below:

[0003] This process not only provides a solution for the byproduct hydrogen chloride but also enables the recycling of chlorine, which is of great significance. However, this process still has many defects and shortcomings, which pose a significant obstacle to its large-scale industrialization.

[0004] For example, most research on this process to date has used high-purity hydrogen chloride as a raw material. However, a significant source of hydrogen chloride is the waste gas from various fluorochemical companies. This waste gas often contains large amounts of fluorides. During the catalytic oxidation of hydrogen chloride, these fluorides react with the active components of the catalyst to form metal fluorides, causing the loss of active components and catalyst deactivation, ultimately preventing the catalytic reaction from proceeding. Purifying the hydrogen chloride raw material through pretreatment to remove fluorides would significantly increase investment costs, while also raising the operating and maintenance costs of the entire equipment, potentially leading to overall losses and making the process impractical for industrial application.

[0005] Furthermore, existing catalysts developed for this process still have many drawbacks, such as insufficient catalytic activity, toxic and harmful components that increase process risks and cause environmental problems, insufficient catalyst stability, and short lifespan. Although relevant companies and research institutions in this field have invested significant human and financial resources in long-term research, they have been unable to achieve a breakthrough for a long time.

[0006] Therefore, there is an urgent need in the field to develop a new technology that can solve the above problems in order to promote the recycling of the huge amount of hydrogen chloride waste gas containing fluoride impurities generated by fluorochemical enterprises. Summary of the Invention

[0007] To address the aforementioned problems, the inventors, through extensive and in-depth research, developed a novel catalyst and its synthesis method. They also developed a method for catalytically oxidizing hydrogen chloride waste gas containing fluoride impurities using the aforementioned catalyst to produce chlorine gas, successfully solving the problems of existing technologies.

[0008] The first aspect of this application provides a catalyst suitable for the catalytic oxidation of hydrogen chloride (containing fluoride impurities) to produce chlorine, said catalyst having a core-shell structure and comprising: An internal core, comprising nickel oxide or titanium oxide; An active layer comprising oxides of one or more of the following elements: ruthenium, rhodium, palladium, copper, nickel, molybdenum, and rare earth elements; The cladding layer comprises titanium oxide when the core contains nickel oxide; and the cladding layer comprises nickel oxide when the core contains titanium oxide. The catalyst comprises, from the inside out, a core, an active layer, and a coating layer; or, from the inside out, a core, a coating layer, and an active layer.

[0009] According to one embodiment of the first aspect of this application, the catalyst further has an outer layer comprising molybdenum oxide.

[0010] According to another embodiment of the first aspect of this application, based on the total weight of the catalyst, the content of the core is 10-90% by weight, the content of the active layer is 0.1-20% by weight, and the content of the coating layer is 10-90% by weight.

[0011] According to another embodiment of the first aspect of this application, when the catalyst has an outer layer, the content of the outer layer is 1-50% by weight based on the total weight of the catalyst.

[0012] A second aspect of this application provides a method for preparing the catalyst of the present invention, the method comprising: Step 1: React the first metal precursor with an alkaline reagent to generate a first precipitate, and then subject the first precipitate to a first calcination. The first metal precursor is a soluble salt of nickel or titanium. Step 2A: Impregnate the product obtained in Step 1 or Step 2B with a second metal precursor solution, and then subject the impregnated material to a second calcination. The second metal precursor is a soluble salt of one or more of the following metal elements: ruthenium, rhodium, palladium, copper, nickel, molybdenum, and rare earth elements. Step 2B: Deposit a third metal on the surface of the product obtained in Step 1 or Step 2A using a third metal precursor solution, and perform a third calcination; when the first metal precursor is a nickel-soluble salt, the third metal precursor is a titanium-soluble salt; when the first metal precursor is a titanium-soluble salt, the third metal precursor is a nickel-soluble salt. Step 2B is performed after step 2A, or step 2B is performed before step 2A.

[0013] According to another embodiment of the second aspect of this application, the method further includes step 3: forming an outer layer containing molybdenum oxide on the solid obtained in step 2A or step 2B by hydrothermal reaction and a fourth calcination.

[0014] According to another embodiment of the second aspect of this application, the temperature of the first roasting is 400-900℃, the temperature of the second roasting is 450-900℃, the temperature of the third roasting is 400-900℃, and the temperature of the fourth roasting is 400-900℃.

[0015] According to another embodiment of the second aspect of this application, the hydrothermal reaction in step 3 is carried out as follows: a solution is prepared using a soluble molybdenum salt, sugars, and organic acids, and the solid product obtained in step 2A or step 2B is added to it. The resulting mixture is then reacted under hydrothermal conditions at 120-180°C for 4-48 hours.

[0016] A third aspect of this application provides a catalytic reaction method comprising catalytically oxidizing a hydrogen chloride feedstock to produce chlorine gas in the presence of a catalyst, wherein the catalyst is the method of this invention, and the hydrogen chloride feedstock contains a fluorine-containing compound.

[0017] According to another embodiment of the third aspect of this application, the catalytic reaction method uses oxygen as an oxidant, and the volume ratio of hydrogen chloride to oxygen is 0.5:1 to 6:1.

[0018] According to another embodiment of the third aspect of this application, the temperature of the catalytic reaction is 200-600°C; the reaction pressure is 0.1-1 MPa; the content of fluorine-containing compounds in the hydrogen chloride feedstock is 1-500 ppm, and the fluorine-containing compounds include one or more of the following: hydrogen fluoride, fluoroalkanes, and fluoroolefins.

[0019] In the detailed embodiments section below, the method and composite adsorbent of this application will be further described with reference to the accompanying drawings. Attached Figure Description

[0020] Figure 1A A schematic diagram of a catalyst core-shell structure according to one embodiment of this application is shown; Figure 1B A schematic diagram of a catalyst core-shell structure according to another embodiment of this application is shown; Figure 2 A TEM image of a catalyst prepared according to an embodiment of this application is shown, in which a distinct coating structure can be seen; Figure 3 As shown in one embodiment of this application, the mapping characterization technique revealed that the active component ruthenium was distributed very uniformly after the reaction, and no obvious particle aggregation was observed. Detailed Implementation

[0021] The “range” disclosed in this document takes the form of a lower limit and an upper limit. It can be one or more lower limits and one or more upper limits, respectively. A given range is defined by selecting a lower limit and an upper limit. The selected lower and upper limits define the boundaries of the particular range. All ranges that can be defined in this way are inclusive and composable; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is also expected that ranges of 60-110 and 80-120 are also included. Furthermore, if the minimum range values ​​are listed as 1 and 2, and if the maximum range values ​​are listed as 3, 4, and 5, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5.

[0022] In this application, unless otherwise stated, the numerical range "ab" is a shortened representation of any combination of real numbers from a to b, where a and b are real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" have been listed in this document, and "0-5" is simply a shortened representation of these numerical combinations.

[0023] Unless otherwise specified in this application, all embodiments and preferred embodiments mentioned herein can be combined to form new technical solutions.

[0024] Unless otherwise specified, all technical features and preferred features mentioned herein can be combined to form new technical solutions.

[0025] In this application, unless otherwise specified, the term "comprising" as used herein can be either open-ended or closed-ended. For example, "comprising" may mean that it may also include other components not listed, or it may only include the listed components.

[0026] The catalyst of this application has a core-shell structure, comprising a core, an active layer, a coating layer, and possibly an outermost layer. The core is located at the innermost part of the catalyst, and the order of the inner and outer layers of the active layer and the coating layer can be interchanged.

[0027] Specifically, according to some embodiments of this application, in order from the inside out, the core-shell catalyst includes a core, an active layer, and a coating layer, but does not have an outer layer, and has the following characteristics: Figure 1A The structure shown.

[0028] According to other embodiments of this application, the core-shell catalyst comprises a core, an active layer, a coating layer, and an outer layer, in an order from the inside out, having the following characteristics: Figure 1B The structure shown.

[0029] According to some other embodiments of this application, the core-shell catalyst includes a core, a coating layer, and an active layer in an inside-out order, but does not have an outer layer. According to some other embodiments of this application, the core-shell catalyst includes a core, a coating layer, an active layer, and an outer layer in an inside-out order. Neither of these cases is shown in the accompanying drawings.

[0030] It should be noted here that, Figure 1A and Figure 1B This is merely a schematic diagram, and only shows a cross-sectional view of half of the catalyst.

[0031] According to one embodiment of this application, the catalyst is in the form of powder, fine particles, or microspheres, and generally has an irregular shape that is spherical, ellipsoidal, or nearly spherical. According to another embodiment of this application, the particle size of the catalyst is 15 nanometers to 100 micrometers, or 20 nanometers to 1 micrometer, or within a numerical range obtained by combining any two of the following endpoints: 15 nanometers, 20 nanometers, 30 nanometers, 50 nanometers, 60 nanometers, 80 nanometers, 100 nanometers, 200 nanometers, 500 nanometers, 1 micrometer, 2 micrometers, 5 micrometers, 10 micrometers, 15 micrometers, 20 micrometers, 30 micrometers, 40 micrometers, 50 micrometers, 80 micrometers, and 100 micrometers.

[0032] According to one embodiment of this application, the core of the catalyst comprises nickel oxide or titanium oxide, preferably nickel oxide. According to another embodiment of this application, the content of the core, based on the total weight of the catalyst, is 10-90% by weight, or 15-85% by weight, or within a range obtained by combining any two of the following endpoints: 10% by weight, 15% by weight, 20% by weight, 25% by weight, 30% by weight, 35% by weight, 40% by weight, 45% by weight, 50% by weight, 55% by weight, 60% by weight, 65% by weight, 70% by weight, 75% by weight, 80% by weight, 85% by weight, 90% by weight.

[0033] According to another embodiment of this application, the active layer of the catalyst comprises oxides of one or more of the following elements: ruthenium, rhodium, palladium, copper, nickel, molybdenum, and rare earth elements. The rare earth elements are selected from one or more of the following: yttrium, lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium. Preferably, the rare earth elements are selected from one or more of the following: lanthanum, cerium, and samarium.

[0034] According to an exemplary embodiment of this application, the active layer contains only ruthenium oxide.

[0035] According to another exemplary embodiment of this application, the active layer comprises ruthenium oxide and copper oxide, wherein the weight ratio of ruthenium oxide to copper oxide is 1:100 to 20:1, for example, 1:5 to 5:1, or within the range of values ​​obtained by combining any two of the following endpoints: 1:100, 1:90, 1:80, 1:70, 1:50, 1:30, 1:20, 1:10, 1:8, 1:6, 1:5, 1:4, 1:3, 1:2, 1:1, 2:1, 3:1, 4:1, 5:1, 8:1, 10:1, 12:1, 15:1, 20:1.

[0036] According to another exemplary embodiment of this application, the active layer contains only copper oxide.

[0037] According to another exemplary embodiment of this application, the active layer comprises ruthenium oxide, copper oxide, and cerium oxide, wherein the weight ratio of ruthenium oxide to copper oxide is 1:100 to 20:1, for example, 1:5 to 5:1, or within a numerical range obtained by combining any two of the following endpoints: 1:100, 1:90, 1:80, 1:70, 1:50, 1:30, 1:20, 1:10, 1:8, 1:6, 1:5, 1:4, 1:3, 1:2, 1:1, 2:1, 3:1, 4:1, 5:1, 8:1. 10:1, 12:1, 15:1, 20:1; the weight ratio of ruthenium oxide to cerium oxide is 1:100 to 20:1, for example, 1:5 to 5:1, or within the range of any combination of the following two endpoints: 1:100, 1:90, 1:80, 1:70, 1:50, 1:30, 1:20, 1:10, 1:8, 1:6, 1:5, 1:4, 1:3, 1:2, 1:1, 2:1, 3:1, 4:1, 5:1, 8:1, 10:1, 12:1, 15:1, 20:1.

[0038] According to another embodiment of this application, based on the total weight of the catalyst, the content of the active layer is 0.1-20% by weight, or 0.5-10% by weight, or within the range of any combination of the following two endpoints: 0.1% by weight, 0.2% by weight, 0.5% by weight, 0.8% by weight, 1% by weight, 2% by weight, 3% by weight, 4% by weight, 5% by weight, 6% by weight, 7% by weight, 8% by weight, 9% by weight, 10% by weight, 11% by weight, 12% by weight, 13% by weight, 14% by weight, 15% by weight, 16% by weight, and 18% by weight.

[0039] According to another embodiment of this application, the coating layer comprises nickel oxide or titanium oxide, and the material of the coating layer is different from that of the core. That is, when the core comprises nickel oxide, the coating layer comprises titanium oxide; and when the core comprises titanium oxide, the coating layer comprises nickel oxide.

[0040] According to another embodiment of this application, based on the total weight of the catalyst, the content of the coating layer is 10-90% by weight, or 15-85% by weight, or within the range of any combination of the following two endpoints: 10% by weight, 15% by weight, 20% by weight, 25% by weight, 30% by weight, 35% by weight, 40% by weight, 45% by weight, 50% by weight, 55% by weight, 60% by weight, 65% by weight, 70% by weight, 75% by weight, 80% by weight, 85% by weight, and 90% by weight.

[0041] As described above, the catalyst of the present invention may or may not include an outer layer. The outer layer comprises molybdenum oxide and contains substantially no other metal oxides.

[0042] According to another embodiment of this application, based on the total weight of the catalyst, the content of the outer layer is 1-50% by weight, or 2-30% by weight, or within the range of any combination of the following two endpoints: 1% by weight, 1.5% by weight, 2% by weight, 3% by weight, 4% by weight, 5% by weight, 8% by weight, 10% by weight, 12% by weight, 15% by weight, 20% by weight, 25% by weight, 30% by weight, 35% by weight, 40% by weight, 45% by weight, and 50% by weight.

[0043] According to one embodiment of this application, the method for preparing the catalyst can sequentially apply various layers on top of the core as needed.

[0044] For example, when the catalyst comprises a core-active layer-coating layer in the order from the inside out, the catalyst synthesis method sequentially includes steps 1, 2A, and 2B; when the catalyst comprises a core-coating layer-active layer in the order from the inside out, the catalyst synthesis method sequentially includes steps 1, 2B, and 2A; when the catalyst comprises a core-active layer-coating layer-outer layer in the order from the inside out, the catalyst synthesis method sequentially includes steps 1, 2A, 2B, and 3; when the catalyst comprises a core-coating layer-active layer-outer layer in the order from the inside out, the catalyst synthesis method sequentially includes steps 1, 2B, 2A, and 3.

[0045] According to one embodiment of this application, the nucleus can be formed by preparing an aqueous solution or organic solution (e.g., an ethanol solution) using a soluble salt of nickel or titanium, then adding an alkaline reagent to form a solid precipitate, separating the solid precipitate, drying it, and then calcining it. Examples of soluble salts of nickel include one or more of the following: nickel sulfate (NiSO4), nickel chloride (NiCl2), and nickel nitrate (Ni(NO3)2). Examples of soluble salts of titanium include one or more of the following: titanium tetrachloride, titanium sulfate, titanium oxysulfate, tetrabutyl titanate, tetramethyl titanate, and tetraisopropyl titanate. The alkaline reagent can be an inorganic or organic base, such as potassium hydroxide, sodium hydroxide, or ammonia. The first roasting in step 1 can be carried out at a temperature of 400-950°C, for example, 550-850°C, or the temperature of the first roasting can be within the numerical range of the following two endpoints: 400°C, 450°C, 500°C, 550°C, 600°C, 650°C, 700°C, 750°C, 800°C, 850°C. The duration of the first roasting can be 1-12 hours, preferably 4-6 hours.

[0046] According to this application, in step 2A, the active layer can be formed by impregnating the core (when the active layer is inside the coating layer) or the core with the coating layer (when the active layer is outside the coating layer) with an aqueous solution of a soluble metal salt of one or more active metal elements selected for forming the active layer, followed by drying and then calcination. The calcination in step 2A can be carried out at a temperature of 400-950°C, for example, 450-850°C, or the calcination temperature can be within the numerical range of the following two endpoints: 400°C, 450°C, 500°C, 550°C, 600°C, 650°C, 700°C, 750°C, 800°C, and 850°C. The duration of the calcination can be 1-12 hours, preferably 4-6 hours.

[0047] The soluble salt of the active metal element in the active layer is selected from one or more of the following: nitrates, sulfates, chlorides, phosphates, metal salts, halometalates, organic acid salts (e.g., formates, acetates, etc.), coordination compounds, etc. For example, when the active layer contains ruthenium, the water-soluble salt of ruthenium may include one or more of the following: ruthenium halides (e.g., RuCl3), carbonyl complexes (e.g., Ru3(CO)). 12 The active layer may contain lanthanum sulfate, lanthanum chloride, cerium chloride, samarium nitrate, and samarium chloride. When copper is present in the active layer, the water-soluble salts of copper may include one or more of the following: copper sulfate, copper chloride, and copper nitrate. When lanthanum and cerium are present in the active layer, the water-soluble salts of lanthanum and cerium may include one or more of the following: lanthanum nitrate, lanthanum chloride, cerium nitrate, cerium chloride, samarium nitrate, and samarium chloride.

[0048] In cases where the active layer contains two or more metal elements, an aqueous solution of each metal element is prepared separately, and the impregnation operation is performed independently with an aqueous solution of one metal element, followed by the above-mentioned calcination. Then, the impregnation operation is performed with an aqueous solution of the next metal element, and then the above-mentioned calcination is performed again.

[0049] The immersion time for each metal can be 1-48 hours, preferably 12-24 hours.

[0050] According to one embodiment of this application, in step 2A, after impregnating the solid material with an aqueous solution of an active metal element, the mixture is not washed or separated, but is directly dried and calcined, thereby impregnating all the active metal elements in the impregnation solution onto the solid material.

[0051] In step 2B, the coating layer can be formed by dispersing the solid particles obtained in the preceding steps in an aqueous solution or organic solution (e.g., an ethanol solution) of titanium or nickel, followed by hydrolysis or a hydrothermal reaction (the temperature of the hydrolysis or hydrothermal reaction can be 60-200°C, for example 70-180°C), forming a titanium oxide or nickel oxide layer on the surface of the solid particles (core or core with an active layer), and then calcining. The calcination in step 2B can be carried out at a temperature of 400-950°C, for example 450-850°C, or the calcination temperature can be within the numerical range of the following two endpoints: 400°C, 450°C, 500°C, 550°C, 600°C, 650°C, 700°C, 750°C, 800°C, 850°C. The duration of the calcination can be 1-12 hours, preferably 4-6 hours.

[0052] Examples of nickel-soluble salts in step 2B include one or more of the following: nickel sulfate (NiSO4), nickel chloride (NiCl2), and nickel nitrate (Ni(NO3)2). Examples of titanium-soluble salts include one or more of the following: titanium tetrachloride, titanium sulfate, titanium oxysulfate, tetrabutyl titanate, tetramethyl titanate, and tetraisopropyl titanate.

[0053] In step C, the outer layer can be formed by a hydrothermal reaction and calcination on the solid particles obtained in the preceding steps, forming an outer layer containing molybdenum oxide. For example, the soluble molybdenum salt can be ammonium molybdate. The hydrothermal reaction can also use sugars and organic acids, examples of which include glucose and acrylic acid. The temperature of the hydrothermal reaction in step C can be 100-180°C, preferably 120-160°C; the duration of the hydrothermal reaction can be 2-24 hours, preferably 8-12 hours. The calcination in step 3 can be carried out at a temperature of 400-950°C, for example 450-850°C, or the calcination temperature can be within the numerical range of the following two endpoints: 400°C, 450°C, 500°C, 550°C, 600°C, 650°C, 700°C, 750°C, 800°C, 850°C. The duration of the calcination can be 1-12 hours, preferably 4-6 hours.

[0054] According to another embodiment of this application, the drying steps in steps 1, 2A, 2B and 3 above can be carried out at a temperature of 50-120°C for 3-12 hours.

[0055] According to another embodiment of this application, the water used preferably has high purity, such as distilled water, desalinated water, ultrapure water, or deionized water.

[0056] The catalyst of this application can be used for the catalytic oxidation of hydrogen chloride to synthesize chlorine. The inventors unexpectedly discovered that when the hydrogen chloride feedstock contains fluorine-containing compound impurities, the catalyst exhibits excellent tolerance to fluorine, excellent corrosion resistance, high catalytic activity, and its excellent catalytic performance can be maintained for a long time with good stability, which is beneficial for large-scale industrial production. Furthermore, the catalyst of this invention does not contain toxic components and can be synthesized through a simple and low-requirement process.

[0057] According to one embodiment of this application, the fluorinated compounds contained in the hydrogen chloride feedstock may include hydrogen fluoride, fluoroalkanes (e.g., monofluoromethane, difluoromethane, tetrafluoromethane) and / or fluoroolefins (e.g., tetrafluoropropylene, perfluoropropylene). According to another embodiment of this application, the content of fluorinated compounds in the hydrogen chloride can be 1-500 ppm. According to a specific embodiment, the hydrogen chloride feedstock contains hydrogen fluoride, difluoromethane, tetrafluoropropylene, and perfluoropropylene in a molar ratio of 4:1.5:2:2.5.

[0058] According to one embodiment of this application, the catalytic oxidation reaction of hydrogen chloride is carried out by: loading a catalyst into a reactor (e.g., a tubular fixed-bed reactor), and preheating the raw material hydrogen chloride (containing fluorine-containing compound impurities) and oxygen before introducing them into the reactor to carry out the catalytic oxidation reaction of hydrogen chloride.

[0059] According to one embodiment of this application, the volumetric flow rate ratio of hydrogen chloride to oxygen is 0.5:1 to 6:1, preferably 1:1 to 4:1. According to another embodiment of this application, the hydrogen chloride space velocity is 200-800 L / (kgcat). h), preferably 300-500 L / (kgcat) h).

[0060] According to another embodiment of this application, the reaction temperature is 200-600°C, preferably 300-450°C, and more preferably 330-430°C.

[0061] According to another embodiment of this application, the reaction pressure is 0.1-1 MPa, preferably 0.1-0.5 MPa.

[0062] According to an exemplary embodiment of this application, the volumetric flow rate ratio of hydrogen chloride to oxygen is 2:1, and the space velocity of hydrogen chloride is 500 L / (kgcat). The reaction temperature is 300~450℃ and the reaction pressure is 0.2MPa.

[0063] The following embodiments illustrate the methods of this application in detail, with the aim of providing a better understanding of the content of this application. It should be understood that these embodiments are merely illustrative and not restrictive. Unless otherwise stated, the reagents used in the embodiments are commercially available analytical grade reagents. Unless otherwise specified, the methods and conditions used in the embodiments are conventional methods and conditions.

[0064] Example

[0065] The water used in the following examples was deionized water, and all other reagents were analytical grade, purchased commercially, and used directly without further treatment. The hydrogen chloride feedstock for the catalytic oxidation reaction in the examples was provided by Shanghai Chlor-Alkali Chemical Co., Ltd., and contained a total of 5 ppm, 20 ppm, or 100 ppm of fluorinated compounds, including hydrogen fluoride, difluoromethane, tetrafluoropropylene, and perfluoropropylene, in a molar ratio of 4:1.5:2:2.5.

[0066] Example 1

[0067] In this embodiment, the catalyst was first prepared according to the following steps: (1) Dissolve 73.380 g of nickel nitrate in 1100 mL of deionized water. Turn on the magnetic stirrer and after it is completely dissolved, add 400 mL of 1 mol / L sodium hydroxide solution dropwise. After the addition is complete, continue stirring for 1 hour. Then filter and wash the solid precipitate with water. Dry the washed solid in a vacuum drying oven at 60 °C overnight, and then transfer it to a muffle furnace and calcine at 550 °C for 5 hours to obtain nickel oxide.

[0068] (2) Dissolve 1.45 g of ruthenium chloride in 9 mL of deionized water and stir for 30 minutes until completely dissolved. Add the nickel oxide powder obtained in the above steps and impregnate for 24 hours under stirring. Then transfer the impregnated material to a vacuum drying oven and dry at 60°C overnight. After that, transfer the dried solid to a muffle furnace and calcine at 550°C for 5 hours.

[0069] (3) Disperse the solid particles obtained in the above steps in 450 ml of ethanol, add 13.210 g of tetrabutyl titanate and 23 g of ammonia water with a concentration of 28% dropwise, stir the mixture continuously for 5 hours under heating conditions of 70°C, then filter, wash with water, transfer the solid into a vacuum drying oven and dry overnight at 60°C, and then transfer the obtained dried solid into a muffle furnace and calcine at 550°C for 5 hours.

[0070] Figure 2 The TEM image of the catalyst particles obtained by the above operation is shown, from which a clear coating structure can be seen.

[0071] The catalyst will then be used in the catalytic oxidation reaction of hydrogen chloride according to the following steps: The fixed-bed reactor tube is filled with empty carrier, catalyst and empty carrier in sequence from bottom to top, with the catalyst loading amount being 20 grams.

[0072] Hydrogen chloride (containing 5 ppm of fluorine compounds) and oxygen were introduced into the reactor at a volumetric flow rate ratio of 2:1, with a hydrogen chloride space velocity of 500 L / (kgcat). The reaction temperature was 400℃ and the reaction pressure was 0.2MPa.

[0073] The reaction products were condensed and the chlorine content was quantitatively analyzed by iodometric titration. The tail gas was absorbed by alkaline solution before being discharged. Since no side reactions occur in the catalytic oxidation reaction of hydrogen chloride, the conversion rate of hydrogen chloride can be expressed by the following formula:

[0074] In this example, the hydrogen chloride conversion rate was 85.0% after the reaction continued for 20 hours and 77.0% after the reaction continued for 2000 hours.

[0075] Figure 3 The distribution of ruthenium, the active component, in the catalyst after the reaction was determined using mapping characterization techniques. The results showed that the ruthenium distribution was very uniform after the reaction, and no obvious particle agglomeration was observed.

[0076] Example 1-1

[0077] In this embodiment, the steps of Example 1 are repeated to synthesize the catalyst, except that the calcination temperature used in (3) is changed from 550°C to 850°C.

[0078] The catalyst prepared in this example was subjected to the same steps as in Example 1 for the catalytic oxidation of hydrogen chloride. The results showed that the hydrogen chloride conversion rate was 90.5% after the reaction was carried out for 20 hours and 84.0% after the reaction was carried out for 2000 hours.

[0079] Examples 1-2

[0080] In this embodiment, the steps of Example 1 are repeated for catalyst synthesis, except that (3) is omitted.

[0081] The catalyst prepared in this example was subjected to the same steps as in Example 1 for the catalytic oxidation of hydrogen chloride. The results showed that the hydrogen chloride conversion rate was 83.7% after the reaction was carried out for 20 hours and 73.0% after the reaction was carried out for 2000 hours.

[0082] Examples 1-3

[0083] In this embodiment, the steps of Example 1 are repeated for catalyst synthesis, except that (2) of this embodiment is carried out in the following manner: 1.98 g of ruthenium chloride is dissolved in 9 mL of deionized water and stirred for 30 minutes until completely dissolved. The nickel oxide powder obtained in the above step is added to the solution, and impregnation is carried out for 24 hours under stirring conditions. The impregnated material is then transferred to a vacuum drying oven and dried overnight at 60°C. The resulting dried solid is then transferred to a muffle furnace and calcined at 550°C for 5 hours. Subsequently, 0.89 g of copper chloride is dissolved in 10 mL of deionized water and stirred for 30 minutes until completely dissolved. The ruthenium-impregnated nickel oxide powder obtained in the above step is added to the solution, and impregnation is carried out for 24 hours under stirring conditions. The impregnated material is then transferred to a vacuum drying oven and dried overnight. The resulting dried solid is then transferred to a muffle furnace and calcined at 550°C for 5 hours. In this embodiment, (3) is carried out in the following manner: the solid particles obtained in the above steps are dispersed in 450 ml of ethanol, and 13.210 g of tetrabutyl titanate and 23 g of ammonia water with a concentration of 28% are added dropwise. The mixture is stirred continuously for 5 hours under heating conditions of 70°C, then filtered, washed with water, and the solid is transferred into a vacuum drying oven and dried overnight at 60°C. Then the dried solid is transferred into a muffle furnace and calcined at 850°C for 5 hours.

[0084] The catalyst prepared in this example was subjected to the same steps as in Example 1 for the catalytic oxidation of hydrogen chloride. The results showed that the hydrogen chloride conversion rate was 92.5% after the reaction was carried out for 20 hours and 85.5% after the reaction was carried out for 2000 hours.

[0085] Examples 1-4

[0086] In this embodiment, the steps of Example 1 are repeated for catalyst synthesis, except that (2) of this embodiment is carried out as follows: 1.98 g of ruthenium chloride is dissolved in 9 mL of deionized water and stirred for 30 minutes until completely dissolved. The nickel oxide powder obtained in the above step is added to the solution, and impregnation is carried out for 24 hours under stirring conditions. The impregnated material is then transferred to a vacuum drying oven and dried overnight. The resulting dried solid is then transferred to a muffle furnace and calcined at 550°C for 5 hours. Subsequently, 0.89 g of copper chloride is dissolved in 10 mL of deionized water and stirred for 30 minutes until completely dissolved. The ruthenium-impregnated nickel oxide powder obtained in the above step is added to the solution, and impregnation is carried out for 24 hours under stirring conditions. The impregnated material is then transferred to a vacuum drying oven and dried overnight. The resulting dried solid is then transferred to a muffle furnace and calcined at 550°C for 5 hours. In this embodiment, (3) is carried out in the following manner: the solid particles obtained in the above steps are dispersed in 450 ml of ethanol, and 13.210 g of tetrabutyl titanate and 23 g of ammonia water with a concentration of 28% are added dropwise. The mixture is stirred continuously for 5 hours under heating conditions of 70°C, then filtered, washed with water, and the solid is transferred into a vacuum drying oven and dried overnight at 60°C. Then the dried solid is transferred into a muffle furnace and calcined at 850°C for 5 hours.

[0087] This embodiment also includes (4): dissolving 1.68 g of ammonium molybdate, 0.083 g of glucose, and 0.135 g of acrylic acid in 30 mL of deionized water, then adding the solid obtained in (3) to the solution, dispersing it under ultrasonic conditions for 1 hour, and then transferring the mixture into a hydrothermal reactor for crystallization at 160°C for 10 hours. The hydrothermal reactor is then cooled to room temperature, opened, and the material removed and filtered. The solid is transferred to a vacuum drying oven and dried overnight at 60°C. The resulting dried solid is then transferred to a muffle furnace and calcined at 450°C for 5 hours.

[0088] The catalyst prepared in this example was subjected to the same steps as in Example 1 for the catalytic oxidation of hydrogen chloride. The results showed that the hydrogen chloride conversion rate was 92.0% after the reaction was carried out for 20 hours and 87.8% after the reaction was carried out for 2000 hours.

[0089] Examples 1-5

[0090] In this embodiment, the catalyst was first prepared according to the following steps: (1) Repeat step (1) of Example 1 to obtain nickel oxide.

[0091] (2) Dissolve 0.89 g of copper chloride in 10 mL of deionized water and stir for 30 minutes until completely dissolved. Add the nickel oxide powder obtained in the above steps and impregnate for 24 hours under stirring. Then transfer the impregnated material to a vacuum drying oven and dry at 60 °C overnight. After that, transfer the dried solid to a muffle furnace and calcine at 550 °C for 5 hours.

[0092] The catalyst prepared in this example was subjected to the same steps as in Example 1 for the catalytic oxidation of hydrogen chloride. The results showed that the hydrogen chloride conversion rate was 79.0% after the reaction was carried out for 20 hours and 60.0% after the reaction was carried out for 2000 hours.

[0093] Example 2

[0094] In this embodiment, the catalyst was first prepared according to the following steps: (1) Dissolve 73.380 g of nickel nitrate in 1100 mL of deionized water. Turn on the magnetic stirrer and after it is completely dissolved, add 400 mL of 1 mol / L sodium hydroxide solution dropwise. After the addition is complete, continue stirring for 1 hour. Then filter and wash the solid precipitate with water. Dry the washed solid in a vacuum drying oven at 60 °C overnight, and then transfer it to a muffle furnace and calcine at 550 °C for 5 hours to obtain nickel oxide.

[0095] (2) The solid particles obtained in the above steps were dispersed in 450 ml of ethanol, and 13.210 g of tetrabutyl titanate and 23 g of 28% ammonia water were added dropwise. The mixture was stirred continuously for 5 hours under heating conditions of 70°C, then filtered, washed with water, and the solid was transferred to a vacuum drying oven and dried overnight at 60°C. The resulting dried solid was then transferred to a muffle furnace and calcined at 850°C for 5 hours.

[0096] (3) Dissolve 1.45 g of ruthenium chloride in 9 mL of deionized water and stir for 30 minutes until completely dissolved. Add the solid particles obtained in the above steps to the solution and impregnate for 24 hours under stirring. Then transfer the mixture of impregnation solution and solid powder into a vacuum drying oven and dry overnight at 60°C. Then transfer the resulting dried solid into a muffle furnace and calcine at 550°C for 5 hours.

[0097] The catalyst was then used for the catalytic oxidation of hydrogen chloride following the same steps as in Example 1.

[0098] In this example, the hydrogen chloride conversion rate was 90.5% after the reaction continued for 20 hours and 80.0% after the reaction continued for 2000 hours.

[0099] Example 2-1

[0100] In this embodiment, the catalyst was first prepared according to the following steps: (1) Repeat (1) of Example 2.

[0101] (2) Repeat (2) of Example 2.

[0102] (3) Repeat (3) of Example 2.

[0103] (4) Dissolve 1.68 g of ammonium molybdate, 0.083 g of glucose, and 0.135 g of acrylic acid in 30 mL of deionized water. Then add the solid obtained in (3) to the solution and disperse it under ultrasonic conditions for 1 hour. Then transfer the mixture to a hydrothermal reactor and crystallize it at 160 °C for 10 hours. Then cool the hydrothermal reactor to room temperature, open the reactor, remove and filter the material, transfer the solid to a vacuum drying oven and dry it overnight at 60 °C. Then transfer the dried solid to a muffle furnace and calcine it at 450 °C for 5 hours.

[0104] The catalyst was then used for the catalytic oxidation of hydrogen chloride following the same steps as in Example 1.

[0105] In this example, the hydrogen chloride conversion rate was 90.1% after the reaction continued for 20 hours, and 81.5% after the reaction continued for 2000 hours.

[0106] Example 3

[0107] In this embodiment, the catalyst was first prepared according to the following steps: (1) TiO2 was purchased from Adamas as the core.

[0108] (2) Dissolve 1.45 g of ruthenium chloride in 25 mL of deionized water and stir for 30 minutes until completely dissolved. Add 30 g of the above TiO2 and impregnate for 24 hours under stirring. Then transfer the impregnated material to a vacuum drying oven and dry overnight at 60 °C. Then transfer the resulting dried solid to a muffle furnace and calcine at 850 °C for 5 hours.

[0109] (3) Dissolve 5.379 g of nickel chloride, 0.269 g of urea, and 0.43 g of glucose in 45 mL of water. Then disperse the solid particles obtained in the above steps in the solution and sonicate for 1 hour. Then transfer the mixture to a hydrothermal reactor and crystallize at 180°C for 10 hours. Then cool the hydrothermal reactor to room temperature, open the reactor, remove and filter the material, transfer the solid to a vacuum drying oven and dry at 60°C overnight. Then transfer the dried solid to a muffle furnace and calcine at 550°C for 5 hours.

[0110] The catalyst was then used for the catalytic oxidation of hydrogen chloride following the same steps as in Example 1.

[0111] In this example, the hydrogen chloride conversion rate was 90.5% after the reaction continued for 20 hours and 87.0% after the reaction continued for 2000 hours.

[0112] Example 3-1

[0113] In this embodiment, the catalyst was first prepared according to the following steps: (1) Repeat (1) of Example 3.

[0114] (2) Dissolve 1.45 g of ruthenium chloride in 25 mL of deionized water and stir for 30 minutes until completely dissolved. Add 30 g of the above TiO2 and impregnate for 24 hours under stirring. Then transfer the impregnated material to a vacuum drying oven and dry at 60°C overnight. Transfer the resulting dried solid to a muffle furnace and calcine at 850°C for 5 hours. Subsequently, dissolve 0.92 g of copper chloride in 30 mL of deionized water and stir for 30 minutes until completely dissolved. Add the ruthenium-impregnated nickel oxide powder obtained in the above steps and impregnate for 24 hours under stirring. Transfer the mixture of impregnation solution and solid powder to a vacuum drying oven and dry overnight. Transfer the resulting dried solid to a muffle furnace and calcine at 550°C for 5 hours.

[0115] (3) Repeat (3) of Example 3.

[0116] The catalyst was then used for the catalytic oxidation of hydrogen chloride following the same steps as in Example 1.

[0117] In this example, the hydrogen chloride conversion rate was 92.0% after the reaction continued for 20 hours and 88.5% after the reaction continued for 2000 hours.

[0118] Example 3-2

[0119] In this embodiment, the catalyst was first prepared according to the following steps: (1) Repeat (1) of Example 3.

[0120] (2) Dissolve 1.45 g of ruthenium chloride in 25 mL of deionized water and stir for 30 minutes until completely dissolved. Add 30 g of the above TiO2 and impregnate for 24 hours under stirring. Then transfer the impregnated material to a vacuum drying oven and dry overnight at 60°C. Transfer the resulting dried solid to a muffle furnace and calcine at 850°C for 5 hours. Subsequently, dissolve 0.92 g of copper chloride in 30 mL of deionized water and stir for 30 minutes until completely dissolved. Add the ruthenium-impregnated nickel oxide powder obtained in the above steps and impregnate for 24 hours under stirring. Then transfer the impregnated material to a vacuum drying oven and dry overnight. Transfer the resulting dried solid to a muffle furnace and calcine at 550°C for 5 hours.

[0121] (3) Repeat (3) of Example 3.

[0122] (4) Dissolve 1.68 g of ammonium molybdate, 0.085 g of glucose, and 0.140 g of acrylic acid in 45 mL of deionized water. Then add the solid obtained in (3) to the solution and disperse it under ultrasonic conditions for 1 hour. Then transfer the mixture to a hydrothermal reactor and crystallize it at 160 °C for 10 hours. Then cool the hydrothermal reactor to room temperature, open the reactor, remove and filter the material, transfer the solid to a vacuum drying oven and dry it overnight at 60 °C. Then transfer the dried solid to a muffle furnace and calcine it at 450 °C for 5 hours.

[0123] The catalyst was then used for the catalytic oxidation of hydrogen chloride following the same steps as in Example 1.

[0124] In this example, the hydrogen chloride conversion rate was 92.2% after the reaction continued for 20 hours and 89.3% after the reaction continued for 2000 hours.

[0125] Example 3-3

[0126] In this embodiment, the catalyst was first prepared according to the following steps: (1) Repeat (1) of Example 3.

[0127] (2) Dissolve 1.45 g of ruthenium chloride in 25 mL of deionized water and stir for 30 minutes until completely dissolved. Add 30 g of the above-mentioned TiO2 and impregnate for 24 hours under stirring. Then transfer the impregnated material to a vacuum drying oven and dry at 60°C overnight. Transfer the resulting dried solid to a muffle furnace and calcine at 850°C for 5 hours. Next, dissolve 0.92 g of copper chloride in 30 mL of deionized water and stir for 30 minutes until completely dissolved. Add the ruthenium-impregnated nickel oxide powder obtained in the above steps and impregnate for 24 hours under stirring. Then transfer the impregnated material to a vacuum drying oven and dry overnight. Transfer the resulting dried solid to a muffle furnace and calcine at 550°C for 5 hours. Next, dissolve 3.045 g of cerium nitrate hexahydrate in 30 mL of deionized water and stir for 30 minutes until completely dissolved. Add the solid powder obtained in the above steps and impregnate for 24 hours under stirring. The impregnated material was then transferred to a vacuum drying oven and dried overnight. The resulting dried solid was then transferred to a muffle furnace and calcined at 550°C for 5 hours.

[0128] (3) Repeat (3) of Example 3.

[0129] (4) Dissolve 1.68 g of ammonium molybdate, 0.085 g of glucose, and 0.140 g of acrylic acid in 45 mL of deionized water. Then add the solid obtained in (3) to the solution and disperse it under ultrasonic conditions for 1 hour. Then transfer the mixture to a hydrothermal reactor and crystallize it at 160 °C for 10 hours. Then cool the hydrothermal reactor to room temperature, open the reactor, remove and filter the material, transfer the solid to a vacuum drying oven and dry it overnight at 60 °C. Then transfer the dried solid to a muffle furnace and calcine it at 450 °C for 5 hours.

[0130] The catalyst was then used for the catalytic oxidation of hydrogen chloride following the same steps as in Example 1.

[0131] In this example, the hydrogen chloride conversion rate was 93.1% after the reaction continued for 20 hours and 90.5% after the reaction continued for 2000 hours.

[0132] Examples 3-4

[0133] In this embodiment, the catalyst was prepared by repeating the steps of Examples 3-3.

[0134] Next, the catalyst was used for the catalytic oxidation reaction of hydrogen chloride following the same steps as in Example 1, except that the total amount of fluorine-containing compounds in the hydrogen chloride was 20 ppm.

[0135] In this example, the hydrogen chloride conversion rate was 92.8% after the reaction continued for 20 hours, and 87.5% after the reaction continued for 2000 hours.

[0136] Examples 3-5

[0137] In this embodiment, the catalyst was prepared by repeating the steps of Examples 3-3.

[0138] Next, the catalyst was used for the catalytic oxidation reaction of hydrogen chloride following the same steps as in Example 1, except that the total amount of fluorine-containing compounds in the hydrogen chloride was 100 ppm.

[0139] In this example, the hydrogen chloride conversion rate was 92.1% after the reaction continued for 20 hours and 83.5% after the reaction continued for 2000 hours.

[0140] Example 4

[0141] In this embodiment, the catalyst was first prepared according to the following steps: (1) TiO2 was purchased from Adamas as the core.

[0142] (2) Dissolve 5.379 g of nickel chloride, 0.269 g of urea, and 0.43 g of glucose in 45 mL of water. Then disperse the above TiO2 solid particles in the solution and sonicate for 1 hour. Then transfer the mixture to a hydrothermal reactor and crystallize at 180 °C for 10 hours. Then cool the hydrothermal reactor to room temperature, open the reactor, remove and filter the material, transfer the solid to a vacuum drying oven and dry at 60 °C overnight. Then transfer the dried solid to a muffle furnace and calcine at 550 °C for 5 hours.

[0143] (3) Dissolve 1.45 g of ruthenium chloride in 28 mL of deionized water and stir for 30 minutes until completely dissolved. Add 30 g of the solid particles obtained in the above steps and impregnate for 24 hours under stirring. Then transfer the impregnated material to a vacuum drying oven and dry at 60 °C overnight. Then transfer the dried solid to a muffle furnace and calcine at 850 °C for 5 hours.

[0144] The catalyst was then used for the catalytic oxidation of hydrogen chloride following the same steps as in Example 1.

[0145] In this example, the hydrogen chloride conversion rate was 88.3% after the reaction continued for 20 hours, and 72% after the reaction continued for 2000 hours.

[0146] Example 4-1

[0147] In this embodiment, the catalyst was first prepared according to the following steps: (1) Repeat (1) of Example 4.

[0148] (2) Repeat (2) of Example 4.

[0149] (3) Repeat (3) of Example 4.

[0150] (4) Add 1.68 g of ammonium molybdate, 0.083 g of glucose, and 0.139 g of acrylic acid to deionized water, and then add the solid obtained in (3). Disperse the mixture under ultrasonic conditions for 1 hour, and then transfer the mixture to a hydrothermal reactor and crystallize it at 160°C for 10 hours. Then cool the hydrothermal reactor to room temperature, open the reactor, remove and filter the material, transfer the solid to a vacuum drying oven and dry it overnight at 60°C, and then transfer the dried solid to a muffle furnace and calcine it at 450°C for 5 hours.

[0151] The catalyst was then used for the catalytic oxidation of hydrogen chloride following the same steps as in Example 1.

[0152] In this example, the hydrogen chloride conversion rate was 88.0% after the reaction continued for 20 hours, and 73.0% after the reaction continued for 2000 hours.

Claims

1. A core-shell catalyst, said catalyst having a core-shell structure, comprising: An internal core, comprising nickel oxide or titanium oxide; An active layer comprising oxides of one or more of the following elements: ruthenium, rhodium, palladium, copper, nickel, molybdenum, and rare earth elements; The cladding layer comprises titanium oxide when the core contains nickel oxide; and the cladding layer comprises nickel oxide when the core contains titanium oxide. The catalyst comprises, from the inside out, a core, an active layer, and a coating layer; or, from the inside out, a core, a coating layer, and an active layer.

2. The core-shell catalyst as described in claim 1, characterized in that, The catalyst also has an outer layer comprising molybdenum oxide.

3. The core-shell catalyst as described in claim 1 or 2, characterized in that, Based on the total weight of the catalyst, the core content is 10-90% by weight, the active layer content is 0.1-20% by weight, and the coating layer content is 10-90% by weight; and When the catalyst has an outer layer, the content of the outer layer is 1-50% by weight, based on the total weight of the catalyst.

4. A method for preparing a catalyst according to any one of claims 1-3, the method comprising: Step 1: React the first metal precursor with an alkaline reagent to generate a first precipitate, and then subject the first precipitate to a first calcination. The first metal precursor is a soluble salt of nickel or titanium. Step 2A: Impregnate the product obtained in Step 1 or Step 2B with a second metal precursor solution, and then subject the impregnated material to a second calcination. The second metal precursor is a soluble salt of one or more of the following metal elements: ruthenium, rhodium, palladium, copper, nickel, molybdenum, and rare earth elements. Step 2B: Deposit a third metal on the surface of the product obtained in Step 1 or Step 2A using a third metal precursor solution, and perform a third calcination; when the first metal precursor is a nickel-soluble salt, the third metal precursor is a titanium-soluble salt; when the first metal precursor is a titanium-soluble salt, the third metal precursor is a nickel-soluble salt. Step 2B is performed after step 2A, or step 2B is performed before step 2A.

5. The method as described in claim 4, characterized in that, The method further includes step 3: forming an outer layer containing molybdenum oxide on the solid obtained in step 2A or step 2B by hydrothermal reaction and a fourth calcination.

6. The method as described in claim 4 or 5, characterized in that, The first roasting temperature is 400-900℃, the second roasting temperature is 450-900℃, the third roasting temperature is 400-900℃, and the fourth roasting temperature is 400-900℃.

7. The method as described in claim 5, characterized in that, The hydrothermal reaction in step 3 is carried out as follows: a solution is prepared using soluble molybdenum salt, sugars, and organic acids, and the solid product obtained in step 2A or step 2B is added to it. The resulting mixture is then reacted under hydrothermal conditions at 120-180°C for 4-48 hours.

8. A catalytic reaction method comprising catalytically oxidizing a hydrogen chloride feedstock to produce chlorine gas in the presence of a catalyst, wherein the catalyst is the method of any one of claims 1-3, and the hydrogen chloride feedstock contains a fluorine-containing compound.

9. The method as described in claim 8, characterized in that, The catalytic reaction method uses oxygen as an oxidant, and the volume ratio of hydrogen chloride to oxygen is 0.5:1 to 6:

1.

10. The method as described in claim 8, characterized in that, The temperature of the catalytic reaction is 200-600℃; the reaction pressure is 0.1-1MPa; the content of fluorine-containing compounds in the hydrogen chloride feedstock is 1-500ppm, and the fluorine-containing compounds include one or more of the following: hydrogen fluoride, fluoroalkanes, and fluoroolefins.

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