A catalyst for ethane oxidative dehydrogenation reaction and a preparation method thereof

Abstract

This invention discloses a method for preparing a catalyst for the oxidative dehydrogenation of ethane, comprising the following steps: dissolving ammonium heptamolybdate tetrahydrate, ammonium metavanadate, telluric acid, and a dispersant in deionized water to form a mixed solution; adding an aqueous solution of niobium oxalate to the mixed solution within 15–50 min to form a suspension; then adding an aqueous solution of the template agent polyether P123; and subjecting the process to aging, hydrothermal crystallization, drying, calcination, and removal of the M2 phase to obtain the catalyst for the oxidative dehydrogenation of ethane. This invention introduces a dispersant and the template agent polyether P123 at specific steps in the catalyst preparation process, combined with limiting the time of adding the niobium oxalate aqueous solution to the mixed solution, which effectively improves the pore structure and specific surface area of ​​the catalyst, increases the proportion of high-concentration active sites on its terminal surface, and thus significantly enhances the catalyst's reactivity.

Description

Technical Field

[0001] This invention relates to the field of ethane oxidative dehydrogenation to ethylene technology, specifically to a catalyst for ethane oxidative dehydrogenation reaction and its preparation method. Background Technology

[0002] Ethylene is an important basic feedstock in the petrochemical industry, mainly produced through the traditional steam thermal cracking method. In a typical ethane steam cracking plant for ethylene production, energy costs account for approximately 70% of the production cost. Compared to high-temperature cracking, the oxidative dehydrogenation of ethane to ethylene (ODHE) technology produces a single, easily separable product with a simple separation system. It is a low-energy-consumption route with enormous application potential and has become one of the research hotspots in recent years.

[0003] In the molybdenum-vanadium-niobium-tellurium multi-metal oxide system, the M1 pure-phase catalyst is a promising catalyst system with high activity and strong redox capabilities at relatively low temperatures, making it a current research hotspot for the oxidative dehydrogenation of low-carbon alkanes. The synthesis of the M1 pure-phase catalyst includes hydrothermal synthesis or slurry synthesis, supplemented by appropriate purification processes. However, the preparation process is complex, and the synthesized product is highly sensitive to the parameters and conditions of the preparation process.

[0004] For example, Chinese patent document CN105080575B reported the preparation steps of the catalyst MoVTeNbO: (1) Ammonium heptamolybdate, vanadium oxysulfate, telluric acid, niobium oxalate and surfactant hexadecyltrimethylammonium bromide are used as raw materials, and the molar ratio of each component is Mo:V:Te:Nb:surfactant = 1:0.2~0.4:0.2~0.3:0.1~0.2; The raw materials are mixed according to the above ratio and placed in a special stainless steel reactor, and the mixture is heated from room temperature at 2~10℃ / min. The heating rate is increased to 160-230℃, held for 2-20 hours, and then naturally cooled to room temperature; (3) After aging, it is taken out, filtered, and dried; the dried product is calcined in two stages, the first stage is calcined in air at 300℃ for 2 hours, the second stage is calcined in nitrogen at 400-700℃ for 1-5 hours, and then pulverized into 20-40 mesh to obtain the catalyst; when reacted at 350℃, the ethane conversion rate and ethylene selectivity can reach 70.5% and 95.0% respectively, and the ethylene yield can reach 67.0%.

[0005] Chinese patent document CN108855118B discloses a method for preparing a high specific surface area pure M1 phase MoVTeNbOx catalyst, comprising the following steps: S1) mixing and dissolving a molybdenum-containing compound, a vanadium-containing compound, an antimony-containing compound, a niobium-containing compound, and a protective agent to obtain a precursor-protective agent mixture solution; wherein the protective agent is a surfactant or a small molecule organic acid and its salt; S2) subjecting the precursor-protective agent mixture solution to a hydrothermal reaction and separating it to obtain a solid; S3) calcining the solid in an air atmosphere, then calcining it in an inert gas atmosphere, and then purifying it with hydrogen peroxide to obtain a pure M1 phase MoVTeNbOx catalyst.

[0006] The specific preparation process of the catalyst disclosed in Chinese patent document CN101612564 B is as follows: the molar ratio of the active components is Mo:V:Te:Nb=1:0.2~1.0:0.2~1.0:0.1~0.5; ammonium heptamolybdate, vanadium oxysulfate, telluric acid and niobium oxalate are mixed according to the ratio and placed in a specially made stainless steel reactor. The temperature is increased from room temperature to 160~230℃ at a heating rate of 2~10℃ / min, and the holding time is 2~20 hours. Then it is allowed to cool naturally to room temperature; after aging, it is taken out, filtered, dried, and calcined at 500~700℃ for 2~5 hours.

[0007] Chinese patent document CN104941668B discloses a pure-phase compound of molybdenum-vanadium-niobium-tellurium multi-metal oxide M1 for ethane oxidative dehydrogenation reaction, prepared by the following method: Under a water bath at 60–80°C, ammonium heptamolybdate, vanadium oxysulfate, and telluric acid in an atomic ratio of molybdenum to vanadium to tellurium of 1:0.15–0.30:0.15–0.35 are mixed and dissolved in deionized water to obtain solution A. Ammonium niobate oxalate is dissolved in deionized water to obtain solution B. The atomic ratio of niobium to molybdenum in solution A is 0.05:1–0.20:1, and the volume ratio of solution A to solution B is 2:1. Solutions A and B are cooled to 30–50°C, mixed, and stirred until homogeneous to form a precursor solution. The precursor solution is then... The mixture was placed in a hydrothermal reactor, and the air was replaced with nitrogen. Hydrothermal synthesis was then carried out at 150–200°C for 24–48 hours to obtain a suspension. The suspension was washed and filtered, and the resulting suspension was dried overnight and then ground to obtain a solid-phase precursor of the pure-phase compound M1. The solid-phase precursor was calcined in a nitrogen atmosphere at 550–650°C for 1–3 hours to obtain a mixed-phase compound of molybdenum-vanadium-niobium-tellurium multi-metal oxides M1 and M2. This mixed-phase compound was placed in hydrogen peroxide with a volume fraction of 5–20% and stirred at 50–70°C for 1–3 hours. It was then filtered and dried for 12–24 hours to obtain the pure-phase compound of molybdenum-vanadium-niobium-tellurium multi-metal oxide M1.

[0008] Although the reaction performance of the M1 catalysts disclosed above has been improved, the reaction performance of the M1 catalysts still needs to be improved. Summary of the Invention

[0009] In view of this, the present invention provides a method for preparing a catalyst for the oxidative dehydrogenation reaction of ethane. This method involves adding a dispersant and a template agent in specific steps during the catalyst preparation process to disperse and support the active components, thereby improving the pore structure and specific surface area of ​​the catalyst, forming an ordered pore structure, enhancing catalytic activity, and significantly improving the reaction performance of the catalyst.

[0010] To achieve the above objectives, the present invention provides the following technical solution:

[0011] A method for preparing a catalyst for the oxidative dehydrogenation reaction of ethane includes the following steps:

[0012] (1) Dissolve ammonium heptamolybdate tetrahydrate, ammonium metavanadate, telluric acid and dispersant in deionized water to form a mixed solution;

[0013] (2) Niobium oxalate aqueous solution is added to the mixed solution within 15 to 50 min to form a suspension, and then an aqueous solution of template agent polyether P123 is added. After aging, hydrothermal crystallization reaction, drying, calcination and removal of M2 phase, the M1 phase catalyst for ethane oxidative dehydrogenation reaction is obtained.

[0014] Optionally, in the preparation method of the catalyst for the oxidative dehydrogenation reaction of ethane provided by the present invention, the amount of dispersant added is 0.005 wt% to 0.1 wt% of the mass of the ammonium heptamolybdate tetrahydrate.

[0015] Optionally, in the preparation method of the catalyst for the oxidative dehydrogenation reaction of ethane provided by the present invention, the dispersant is selected from any one of propylene glycol, polymethyl cellulose, polyvinyl alcohol, guar gum, polyethylene glycol and polyvinylpyrrolidone.

[0016] Optionally, in the preparation method of the catalyst for the oxidative dehydrogenation reaction of ethane provided by the present invention, the amount of the template agent polyether P123 added is 0.01wt% to 0.3wt% of the mass of the ammonium heptamolybdate tetrahydrate.

[0017] Optionally, in the preparation method of the catalyst for the oxidative dehydrogenation reaction of ethane provided by the present invention, the aging temperature is 20-90°C and the time is 20-180 min.

[0018] Optionally, in the preparation method of the catalyst for the oxidative dehydrogenation reaction of ethane provided by the present invention, the temperature of the hydrothermal crystallization reaction is 150-200°C and the time is 12-60 h.

[0019] Optionally, in the preparation method of the catalyst for the oxidative dehydrogenation reaction of ethane provided by the present invention, the drying temperature is 70-120°C and the time is 6-20 h.

[0020] Optionally, in the preparation method of the catalyst for the oxidative dehydrogenation reaction of ethane provided by the present invention, the calcination is selected from two-stage calcination; the two-stage calcination includes first calcining in air at 200-400°C for 2-6 hours, and then calcining in an inert atmosphere at 550-650°C for 1-4 hours.

[0021] Optionally, in the preparation method of the catalyst for the oxidative dehydrogenation reaction of ethane provided by the present invention, the M2 phase is removed by purification with hydrogen peroxide, wherein the concentration of hydrogen peroxide is 5wt% to 15wt%, the purification temperature is 30 to 80°C, and the purification time is 30 to 240 min.

[0022] Optionally, in the preparation method of the catalyst for the oxidative dehydrogenation reaction of ethane provided by the present invention, in step (1), the ammonium heptamolybdate tetrahydrate, the ammonium metavanadate, the telluric acid, and the dispersant are dissolved in deionized water. The amount of deionized water is not limited, as long as it is sufficient to dissolve the ammonium heptamolybdate tetrahydrate, ammonium metavanadate, telluric acid, and dispersant. If necessary, heating under stirring can promote the dissolution of the ammonium heptamolybdate tetrahydrate, ammonium metavanadate, telluric acid, and dispersant in deionized water. For example, stirring at 70-100°C for 60-180 min can promote dissolution. The specific amount can be adjusted according to the actual situation.

[0023] Optionally, in the preparation method of the ethane oxidative dehydrogenation catalyst provided by the present invention, the aqueous solution of niobium oxalate is obtained by dissolving niobium oxalate in deionized water. The amount of deionized water is not limited, as long as it is sufficient to dissolve niobium oxalate. If necessary, to save efficiency, heating under stirring can promote the dissolution of niobium oxalate in deionized water. For example, stirring at 60-90°C for 20-60 minutes can be used, and the specific temperature can be adjusted according to the actual situation.

[0024] Optionally, in the preparation method of the ethane oxidative dehydrogenation catalyst provided by the present invention, the aqueous solution of the template agent polyether P123 is obtained by dissolving the template agent polyether P123 in deionized water. The amount of deionized water is not limited, as long as it is sufficient to dissolve the polyether P123. If necessary, to save efficiency, the polyether P123 can be heated under stirring to promote the dissolution of the polyether P123 in the deionized water. For example, it can be stirred at 70-100°C for 120-480 min, and the specific temperature can be adjusted according to the actual situation.

[0025] Optionally, in the preparation method of the above-mentioned ethane oxidative dehydrogenation supported catalyst provided by the present invention, after purification and removal of the M2 phase by hydrogen peroxide, a step of re-drying is further included; preferably, the re-drying temperature is 60-150°C and the time is 5-18h.

[0026] This invention also provides a catalyst for the oxidative dehydrogenation reaction of ethane, prepared by the above-described method for preparing a catalyst for the oxidative dehydrogenation reaction of ethane. The general formula of the catalyst for the oxidative dehydrogenation reaction of ethane is as follows: Mo a V b Te c Nb d Where a = 1, b is 0.25 to 0.32, c is 0.16 to 0.23, and d is 0.08 to 0.15.

[0027] This invention also provides a catalyst for the oxidative dehydrogenation of ethane, prepared by the above-described method for the catalyst of ethane oxidative dehydrogenation, for catalyzing the oxidative dehydrogenation of ethane to ethylene; preferably, the reaction temperature is 350–400°C, the pressure is atmospheric pressure, and the feed space velocity of the reaction gas is 200–500 h⁻¹. -1 The molar ratio of the reaction gas ethane: oxygen: nitrogen is 1:(0.4~0.8):(1.2~2.0).

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0029] The present invention provides a method for preparing a catalyst for the oxidative dehydrogenation reaction of ethane. By introducing a dispersant and a template agent, polyether P123, at specific steps in the catalyst preparation process, and by limiting the time of adding niobium oxalate aqueous solution to the mixed solution, the pore structure and specific surface area of ​​the catalyst can be effectively improved, increasing the proportion of high-concentration active sites on its terminal surface, thereby significantly enhancing the catalyst's reactivity. Specifically, mixing ammonium heptamolybdate tetrahydrate, ammonium metavanadate, telluric acid, and the dispersant can disperse and support the active components such as molybdenum, vanadium, and tellurium, thereby improving the pore structure and specific surface area of ​​the catalyst. Aging after adding the template agent polyether P123 forms an ordered pore structure, increasing the specific surface area. By limiting the time of adding the niobium oxalate aqueous solution to the mixed solution, the rate at which the heteropolyacid anions formed in the initial mixed aqueous solution of Mo, V, and Te mix with the Nb precursor to form a complex is controlled, thereby generating more active species and improving the catalyst's reactivity. The dispersant and template agent polyether P123, combined with the time limit for adding niobium oxalate solution, work together to exert a synergistic effect, which greatly improves the reaction performance of the catalyst prepared by this method. Detailed Implementation

[0030] The present invention will now be described in detail through embodiments. It should be noted that the following embodiments are only for further illustration of the present invention and should not be construed as limiting the scope of protection of the present invention. Those skilled in the art can make some non-essential improvements and adjustments to the present invention based on the above description.

[0031] For any experimental steps or conditions not specified in the examples and comparative examples, the procedures and conditions described in the literature in this field can be followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0032] Raw material sources: All raw materials used in the catalyst preparation process were analytical grade (AR). The raw materials were: ammonium heptamolybdate tetrahydrate, propylene glycol, hydrogen peroxide, polymethyl cellulose, polyvinyl alcohol, polyethylene glycol, polyvinylpyrrolidone, hexadecyltrimethylammonium bromide, and polyether P123, which were purchased from Sinopharm Reagent Co., Ltd.; ammonium metavanadate and telluric acid were purchased from Maclean's Reagent Co.; and niobium oxalate and guar gum powder were purchased from Aladdin Reagent Co.

[0033] Evaluation and analysis methods: The catalysts prepared in the examples and comparative examples were tableted and crushed, sieved to 20-40 mesh, and packed into 10 mL fixed-bed microreactors with an inner diameter of 5 mm. The reaction was carried out at a reaction temperature of 360 °C, atmospheric pressure, and a feed space velocity of 300 h⁻¹. -1 The reaction was carried out for 2 hours under the condition that the molar ratio of ethane:oxygen:nitrogen gas was 1:0.6:1.5, yielding ethylene product. The reaction product was detected by gas chromatography.

[0034] Example 1

[0035] This embodiment provides a catalyst for the oxidative dehydrogenation reaction of ethane, and the specific preparation method includes the following steps:

[0036] (1) Add a certain amount of ammonium heptamolybdate tetrahydrate, ammonium metavanadate, telluric acid and propylene glycol to deionized water and stir at 70°C for 120 min to form a mixed solution; wherein, the amount of propylene glycol added is 0.02 wt% of the mass of ammonium heptamolybdate tetrahydrate.

[0037] (2) Add polyether p123 to deionized water and stir at 80°C for 300 min to obtain an aqueous solution of polyether 123; wherein, the amount of polyether p123 added is 0.1 wt% of the mass of ammonium heptamolybdate tetrahydrate.

[0038] (3) Add a certain amount of niobium oxalate to deionized water and stir at 70°C for 40 min to form an aqueous solution of niobium oxalate;

[0039] (4) Niobium oxalate aqueous solution was added dropwise to the mixed solution (taken 20 min) to form a suspension. Then, an aqueous solution of polyether 123 was added. After aging at 70℃ for 120 min, hydrothermal crystallization was carried out at 150℃ for 24 h, followed by drying at 80℃ for 12 h. The catalyst was calcined at 300℃ for 3.5 h in air atmosphere, and then calcined at 600℃ for 3 h in nitrogen atmosphere. The crude catalyst was placed in 12wt% hydrogen peroxide and stirred at 60℃ for 120 min. The catalyst was purified to remove the M2 phase, and then dried at 80℃ for 10 h to obtain the final catalyst product with the molecular formula Mo1V. 0.28 Te 0.18 Nb 0.12 It is denoted as ODHE-1.

[0040] Example 2

[0041] This embodiment provides a catalyst for the oxidative dehydrogenation reaction of ethane, and the specific preparation method includes the following steps:

[0042] (1) Add a certain amount of ammonium heptamolybdate tetrahydrate, ammonium metavanadate, telluric acid and polymethylcellulose to deionized water, stir at 75°C for 100 min to form a mixed solution. The amount of polymethylcellulose added is 0.005 wt% of the mass of ammonium heptamolybdate tetrahydrate.

[0043] (2) Add polyether p123 to deionized water and stir at 90°C for 180 min to obtain an aqueous solution of polyether p123; the amount of polyether p123 added is 0.3 wt% of the mass of ammonium heptamolybdate tetrahydrate.

[0044] (3) Add a certain amount of niobium oxalate to deionized water and stir at 75°C for 30 minutes to form an aqueous solution of niobium oxalate;

[0045] (4) Add an aqueous solution of niobium oxalate dropwise to the mixed solution (takes 15 min) to form a suspension. Then add an aqueous solution of polyether 123. After aging at 20°C for 100 min, perform hydrothermal crystallization at 170°C for 12 h, and then dry at 80°C for 16 h. Calcinate at 300°C in air for 5 h, and then calcine at 550°C in nitrogen for 2 h. Place the crude catalyst in 8wt% hydrogen peroxide solution and stir at 40°C for 150 min. Purify the catalyst to remove the M2 phase, and then dry at 130°C for 12 h to obtain the final catalyst product with the molecular formula Mo1V. 0.28 Te 0.20 Nb 0.08 It is denoted as ODHE-2.

[0046] Example 3

[0047] This embodiment provides a catalyst for the oxidative dehydrogenation reaction of ethane, and the specific preparation method includes the following steps:

[0048] (1) Add a certain amount of ammonium heptamolybdate tetrahydrate, ammonium metavanadate, telluric acid and polyvinyl alcohol to deionized water, stir at 100℃ for 90 min to form a mixed solution. The amount of polyvinyl alcohol added is 0.007 wt% of the mass of ammonium heptamolybdate tetrahydrate.

[0049] (2) Add polyether p123 to deionized water and stir at 70°C for 400 min to obtain an aqueous solution of polyether p123; the amount of polyether p123 added is 0.25 wt% of the mass of ammonium heptamolybdate tetrahydrate.

[0050] (3) Add a certain amount of niobium oxalate to deionized water and stir at 60°C for 60 min to form an aqueous solution of niobium oxalate;

[0051] (4) Niobium oxalate aqueous solution was added dropwise to the mixed solution (takes 25 min) to form a suspension. Then, polyether p123 aqueous solution was added. After aging at 50°C for 60 min, hydrothermal crystallization was carried out at 175°C for 48 h, followed by drying at 70°C for 18 h. The catalyst was calcined at 200°C for 6 h in air atmosphere, and then calcined at 600°C for 2 h in nitrogen atmosphere. The crude catalyst was placed in 7wt% hydrogen peroxide and stirred at 50°C for 60 min. The catalyst was purified to remove the M2 phase, and then dried at 100°C for 10 h to obtain the final catalyst product with the molecular formula Mo1V. 0.30 Te 0.16 Nb 0.12 It is denoted as ODHE-3.

[0052] Example 4

[0053] This embodiment provides a catalyst for the oxidative dehydrogenation reaction of ethane, and the specific preparation method includes the following steps:

[0054] (1) Add a certain amount of ammonium heptamolybdate tetrahydrate, ammonium metavanadate, telluric acid and guar gum powder to deionized water, stir at 80°C for 85 min to form a mixed solution. The amount of guar gum powder added is 0.01 wt% of the mass of ammonium heptamolybdate tetrahydrate.

[0055] (2) Add polyether p123 to deionized water and stir at 100°C for 200 min to obtain an aqueous solution of polyether p123; the amount of polyether p123 added is 0.15 wt% of the mass of ammonium heptamolybdate tetrahydrate.

[0056] (3) Add a certain amount of niobium oxalate to deionized water and stir at 80°C for 30 minutes to form an aqueous solution of niobium oxalate;

[0057] (4) Add an aqueous solution of niobium oxalate dropwise to the mixed solution (takes 30 min) to form a suspension. Then add an aqueous solution of polyether p123. After aging at 80°C for 180 min, perform hydrothermal crystallization at 180°C for 30 h, and then dry at 80°C for 16 h. Calcinate at 300°C in air for 4 h, and then calcine at 620°C in nitrogen for 2 h. Place the crude catalyst in 10 wt% hydrogen peroxide solution and stir at 60°C for 100 min. Purify the catalyst to remove the M2 phase, and then dry at 120°C for 8 h to obtain the final catalyst product with the molecular formula Mo1V. 0.30 Te 0.18 Nb 0.12 It is denoted as ODHE-4.

[0058] Example 5

[0059] This embodiment provides a catalyst for the oxidative dehydrogenation reaction of ethane, and the specific preparation method includes the following steps:

[0060] (1) Add a certain amount of ammonium heptamolybdate tetrahydrate, ammonium metavanadate, telluric acid and polyethylene glycol to deionized water, stir at 85°C for 180 min to form a mixed solution, and the amount of polyethylene glycol added is 0.1 wt% of the mass of ammonium heptamolybdate tetrahydrate.

[0061] (2) Add polyether p123 to deionized water and stir at 100°C for 200 min to obtain an aqueous solution of polyether p123; the amount of polyether p123 added is 0.05 wt% of the mass of ammonium heptamolybdate tetrahydrate.

[0062] (3) Add a certain amount of niobium oxalate to deionized water and stir at 85°C for 50 minutes to form an aqueous solution of niobium oxalate;

[0063] (4) Niobium oxalate aqueous solution was added dropwise to the mixed solution (takes 25 min) to form a suspension. Then, polyether p123 aqueous solution was added. After aging at 85℃ for 90 min, hydrothermal crystallization reaction was carried out at 190℃ for 20 h, followed by drying at 90℃ for 12 h. The catalyst was calcined at 400℃ for 2 h in air atmosphere, and then calcined at 650℃ for 1 h in nitrogen atmosphere. The crude catalyst was placed in 7.5 wt% hydrogen peroxide and stirred at 70℃ for 80 min. The catalyst was purified to remove the M2 phase, and then dried at 90℃ for 15 h to obtain the final catalyst product with the molecular formula Mo1V. 0.32 Te 0.20 Nb 0.15 It is denoted as ODHE-5.

[0064] Example 6

[0065] This embodiment provides a catalyst for the oxidative dehydrogenation reaction of ethane, and the specific preparation method includes the following steps:

[0066] (1) Add a certain amount of ammonium heptamolybdate tetrahydrate, ammonium metavanadate, telluric acid and polyvinylpyrrolidone to deionized water, stir at 75°C for 150 min to form a mixed solution. The amount of polyvinylpyrrolidone added is 0.05 wt% of the mass of ammonium heptamolybdate tetrahydrate.

[0067] (2) Add polyether p123 to deionized water and stir at 90°C for 480 min to obtain an aqueous solution of polyether 123; the amount of polyether p123 added is 0.01 wt% of the mass of ammonium heptamolybdate tetrahydrate.

[0068] (3) Add a certain amount of niobium oxalate to deionized water and stir at 75°C for 30 minutes to form an aqueous solution of niobium oxalate;

[0069] (4) Niobium oxalate aqueous solution was added dropwise to the mixed solution (taken 20 min) to form a suspension. Then, polyether p123 aqueous solution was added. After aging at 40℃ for 150 min, hydrothermal crystallization reaction was carried out at 160℃ for 36 h, followed by drying at 110℃ for 8 h. The catalyst was calcined at 400℃ for 2.5 h in air atmosphere, and then calcined at 580℃ for 3 h in argon atmosphere. The crude catalyst was placed in 11wt% hydrogen peroxide and stirred at 80℃ for 80 min. The catalyst was purified to remove the M2 phase, and then dried at 110℃ for 6 h to obtain the final catalyst product with the molecular formula Mo1V. 0.25 Te 0.23 Nb 0.10 It is denoted as ODHE-6.

[0070] Example 7

[0071] This embodiment provides a catalyst for the oxidative dehydrogenation reaction of ethane, and the specific preparation method includes the following steps:

[0072] (1) Add a certain amount of ammonium heptamolybdate tetrahydrate, ammonium metavanadate, telluric acid and polyvinyl alcohol to deionized water, stir at 90°C for 60 min to form a mixed solution. The amount of polyvinyl alcohol added is 0.08 wt% of the mass of ammonium heptamolybdate tetrahydrate.

[0073] (2) Add polyether p123 to deionized water and stir at 100°C for 300 min to obtain an aqueous solution of polyether p123; the amount of polyether p123 added is 0.2 wt% of the mass of ammonium heptamolybdate tetrahydrate.

[0074] (3) Add a certain amount of niobium oxalate to deionized water and stir at 80°C for 20 minutes to form an aqueous solution of niobium oxalate;

[0075] (4) Niobium oxalate aqueous solution was added dropwise to the mixed solution (takes 35 min) to form a suspension. Then, polyether p123 aqueous solution was added. After aging at 90℃ for 60 min, hydrothermal crystallization reaction was carried out at 170℃ for 30 h, followed by drying at 85℃ for 15 h. The catalyst was calcined at 350℃ for 3 h in air atmosphere, and then calcined at 610℃ for 4 h in helium atmosphere. The crude catalyst was placed in 8.5 wt% hydrogen peroxide and stirred at 60℃ for 200 min. The catalyst was purified to remove the M2 phase, and then dried at 120℃ for 10 h to obtain the final catalyst product with the molecular formula Mo1V. 0.31 Te 0.19 Nb 0.13 It is denoted as ODHE-7.

[0076] Example 8

[0077] This embodiment provides a catalyst for the oxidative dehydrogenation reaction of ethane, and the specific preparation method includes the following steps:

[0078] (1) Add a certain amount of ammonium heptamolybdate tetrahydrate, ammonium metavanadate, telluric acid and polyvinylpyrrolidone to deionized water, stir at 80°C for 80 min to form a mixed solution. The amount of polyvinylpyrrolidone added is 0.03 wt% of the mass of ammonium heptamolybdate tetrahydrate.

[0079] (2) Add polyether p123 to deionized water and stir at 85°C for 360 min to obtain an aqueous solution of polyether p123; the amount of polyether p123 added is 0.08 wt% of the mass of ammonium heptamolybdate tetrahydrate.

[0080] (3) Add a certain amount of niobium oxalate to deionized water and stir at 80°C for 25 minutes to form an aqueous solution of niobium oxalate;

[0081] (4) Niobium oxalate aqueous solution was added dropwise to the mixed solution (taken 40 min) to form a suspension. Then, polyether p123 aqueous solution was added. After aging at 60℃ for 100 min, hydrothermal crystallization reaction was carried out at 165℃ for 55 h, followed by drying at 120℃ for 10 h. The catalyst was calcined at 350℃ for 4 h in air atmosphere, and then calcined at 630℃ for 2 h in helium atmosphere. The crude catalyst was placed in 5 wt% hydrogen peroxide and stirred at 30℃ for 180 min. The catalyst was purified to remove the M2 phase, and then dried at 70℃ for 8 h to obtain the final catalyst product with the molecular formula Mo1V. 0.29 Te 0.18 Nb 0.14 It is denoted as ODHE-8.

[0082] Example 9

[0083] This embodiment provides a catalyst for the oxidative dehydrogenation reaction of ethane, and the specific preparation method includes the following steps:

[0084] (1) Add a certain amount of ammonium heptamolybdate tetrahydrate, ammonium metavanadate, telluric acid and guar gum powder to deionized water, stir at 90°C for 75 min to form a mixed solution. The amount of guar gum powder added is 0.02 wt% of the mass of ammonium heptamolybdate tetrahydrate.

[0085] (2) Add polyether p123 to deionized water and stir at 95°C for 240 min until completely dissolved to obtain an aqueous solution of polyether p123; the amount of polyether p123 added is 0.18 wt% of the mass of ammonium heptamolybdate tetrahydrate.

[0086] (3) Add a certain amount of niobium oxalate to deionized water and stir at 90°C for 30 minutes to form an aqueous solution of niobium oxalate;

[0087] (4) Add an aqueous solution of niobium oxalate dropwise to the mixed solution (takes 35 min) to form a suspension. Then add an aqueous solution of polyether p123, age at 90℃ for 20 min, and then perform hydrothermal crystallization reaction at 180℃ for 40 h. Then dry at 100℃ for 6 h. Calcinate at 250℃ in air for 4 h, and then calcine at 600℃ in helium for 2 h. Place the crude catalyst in 6wt% hydrogen peroxide and stir at 50℃ for 240 min. Purify the catalyst to remove the M2 phase, and then dry at 100℃ for 8 h to obtain the final catalyst product with the molecular formula Mo1V. 0.30 Te 0.18 Nb 0.10 It is denoted as ODHE-9.

[0088] Example 10

[0089] This embodiment provides a catalyst for the oxidative dehydrogenation reaction of ethane, and the specific preparation method includes the following steps:

[0090] (1) Add a certain amount of ammonium heptamolybdate tetrahydrate, ammonium metavanadate, telluric acid and polyethylene glycol to deionized water, stir at 80°C for 140 min to form a mixed solution, and the amount of polyethylene glycol added is 0.03 wt% of the mass of ammonium heptamolybdate tetrahydrate.

[0091] (2) Add polyether p123 to deionized water and stir at 100°C for 120 min to obtain an aqueous solution of polyether p123; the amount of polyether p123 added is 0.13 wt% of the mass of ammonium heptamolybdate tetrahydrate.

[0092] (3) Add a certain amount of niobium oxalate to deionized water and stir at 80°C for 40 minutes to form an aqueous solution of niobium oxalate;

[0093] (4) Add an aqueous solution of niobium oxalate dropwise to the mixed solution (takes 50 min) to form a suspension. Then add an aqueous solution of polyether p123, age at 30°C for 50 min, and then perform hydrothermal crystallization at 200°C for 16 h. Dry at 90°C for 15 h. Calcine at 250°C for 3 h in air and at 620°C for 3 h in helium atmosphere. Place the crude catalyst in 9 wt% hydrogen peroxide solution and stir at 70°C for 30 min. Purify the catalyst to remove the M2 phase, and then dry at 60°C for 18 h to obtain the final catalyst product with the molecular formula Mo1V. 0.31 Te 0.21 Nb 0.12 It is denoted as ODHE-10.

[0094] Example 11

[0095] This embodiment provides a catalyst for the oxidative dehydrogenation reaction of ethane, and the specific preparation method includes the following steps:

[0096] (1) Add a certain amount of ammonium heptamolybdate tetrahydrate, ammonium metavanadate, telluric acid and guar gum powder to deionized water, stir at 85°C for 70 min to form a mixed solution. The amount of guar gum powder added is 0.01 wt% of the mass of ammonium heptamolybdate tetrahydrate.

[0097] (2) Add polyether p123 to deionized water and stir at 90°C for 420 min to obtain an aqueous solution of polyether 123; the amount of polyether p123 added is 0.16 wt% of the mass of ammonium heptamolybdate tetrahydrate.

[0098] (3) Add a certain amount of niobium oxalate to deionized water and stir at 85°C for 20 minutes to form an aqueous solution of niobium oxalate;

[0099] (4) Niobium oxalate aqueous solution was added dropwise to the mixed solution (takes 40 min) to form a suspension. Then, polyether p123 aqueous solution was added. After aging at 70℃ for 150 min, hydrothermal crystallization was carried out at 175℃ for 60 h, followed by drying at 100℃ for 20 h. The catalyst was calcined at 300℃ for 2 h in air and at 600℃ for 3 h in argon atmosphere. The crude catalyst was then placed in 15 wt% hydrogen peroxide and stirred at 80℃ for 90 min. The catalyst was purified to remove the M2 phase and then dried at 80℃ for 16 h to obtain the final catalyst product with the molecular formula Mo1V. 0.30 Te 0.20 Nb 0.11 It is denoted as ODHE-11.

[0100] Example 12

[0101] This embodiment provides a catalyst for the oxidative dehydrogenation reaction of ethane, and the specific preparation method includes the following steps:

[0102] (1) Add a certain amount of ammonium heptamolybdate tetrahydrate, ammonium metavanadate, telluric acid and guar gum powder to deionized water, stir at 80°C for 85 min to form a mixed solution. The amount of guar gum powder added is 0.5 wt% of the mass of ammonium heptamolybdate tetrahydrate.

[0103] (2) Add polyether p123 to deionized water and stir at 100°C for 200 min to obtain an aqueous solution of polyether p123; the amount of polyether p123 added is 0.005 wt% of the mass of ammonium heptamolybdate tetrahydrate.

[0104] (3) Add a certain amount of niobium oxalate to deionized water and stir at 80°C for 30 minutes to form an aqueous solution of niobium oxalate;

[0105] (4) Niobium oxalate aqueous solution was added in batches to the mixed solution (over 30 min) to form a suspension. Then, polyether p123 aqueous solution was added. After aging at 80℃ for 180 min, hydrothermal crystallization was carried out at 180℃ for 30 h, followed by drying at 80℃ for 16 h. The catalyst was calcined at 300℃ for 4 h in air atmosphere, and then calcined at 620℃ for 2 h in nitrogen atmosphere. The crude catalyst was placed in 10 wt% hydrogen peroxide and stirred at 60℃ for 100 min. The catalyst was purified to remove the M2 phase, and then dried at 120℃ for 8 h to obtain the final catalyst product with the molecular formula Mo1V. 0.30 Te 0.18 Nb 0.12 It is denoted as ODHE-12.

[0106] Comparative Example 1

[0107] The catalyst for the oxidative dehydrogenation of ethane provided in this comparative example is similar to that in Example 4, except that template agent P123 and dispersant guar gum powder are not added in this comparative example. The specific preparation method of the catalyst for the oxidative dehydrogenation of ethane provided in this comparative example includes the following steps:

[0108] (1) Add a certain amount of ammonium heptamolybdate tetrahydrate, ammonium metavanadate and telluric acid to deionized water and stir at 80°C for 90 min to form a mixed solution.

[0109] (2) Add a certain amount of niobium oxalate to deionized water and stir at 80°C for 30 minutes to form an aqueous solution of niobium oxalate;

[0110] (3) An aqueous solution of niobium oxalate was added dropwise to the mixed solution (over 30 min) to form a suspension. After aging at 80°C for 180 min, it was subjected to hydrothermal crystallization at 180°C for 30 h, and then dried at 80°C for 16 h. The catalyst was calcined at 300°C for 4 h in air, and then calcined at 620°C for 2 h in nitrogen atmosphere. The crude catalyst was then placed in 10 wt% hydrogen peroxide solution and stirred at 60°C for 100 min. The catalyst was purified to remove the M2 phase, and then dried at 120°C for 8 h to obtain the final catalyst product with the molecular formula Mo1V. 0.30 Te 0.18 Nb 0.12 It is denoted as ODHE-12.

[0111] Comparative Example 2

[0112] The catalyst for the oxidative dehydrogenation of ethane provided in this comparative example is similar to that in Example 4, except that template agent P123 was not added in this comparative example. The specific preparation method of the catalyst for the oxidative dehydrogenation of ethane provided in this comparative example includes the following steps:

[0113] (1) Add a certain amount of ammonium heptamolybdate tetrahydrate, ammonium metavanadate, telluric acid and guar gum powder to deionized water, stir at 80°C for 85 min to form a mixed solution. The amount of guar gum powder added is 0.04 wt% of the mass of ammonium heptamolybdate tetrahydrate.

[0114] (2) Add a certain amount of niobium oxalate to deionized water and stir at 80°C for 30 minutes to form an aqueous solution of niobium oxalate;

[0115] (3) An aqueous solution of niobium oxalate was added dropwise to the mixed solution (over 30 min) to form a suspension. After aging at 80°C for 180 min, it was subjected to hydrothermal crystallization at 180°C for 30 h, and then dried at 80°C for 16 h. The catalyst was calcined at 300°C for 4 h in air, and then calcined at 620°C for 2 h in nitrogen atmosphere. The crude catalyst was then placed in 10 wt% hydrogen peroxide solution and stirred at 60°C for 100 min. The catalyst was purified to remove the M2 phase, and then dried at 120°C for 8 h to obtain the final catalyst product with the molecular formula Mo1V. 0.30 Te 0.18 Nb 0.12 It is denoted as ODHE-13.

[0116] Comparative Example 3

[0117] The catalyst for the oxidative dehydrogenation of ethane provided in this comparative example is similar to that in Example 4, except that the dispersant guar gum powder is not added in this comparative example. The specific preparation method of the catalyst for the oxidative dehydrogenation of ethane provided in this comparative example includes the following steps:

[0118] (1) Add a certain amount of ammonium heptamolybdate tetrahydrate, ammonium metavanadate and telluric acid to deionized water and stir at 80°C for 85 min to form a mixed solution;

[0119] (2) Add polyether p123 to deionized water and stir at 100°C for 200 min to obtain an aqueous solution of polyether p123; the amount of p123 added is 0.15 wt% of the mass of ammonium heptamolybdate tetrahydrate.

[0120] (3) Add a certain amount of niobium oxalate to deionized water and stir at 80°C for 30 minutes to form an aqueous solution of niobium oxalate;

[0121] An aqueous solution of niobium oxalate was added dropwise to the mixed solution (over 30 minutes) to form a suspension. Then, an aqueous solution of polyether p123 was added. After aging at 80°C for 180 minutes, hydrothermal crystallization was carried out at 180°C for 30 hours, followed by drying at 80°C for 16 hours. The catalyst was calcined at 300°C for 4 hours in air, and then calcined at 620°C for 2 hours in nitrogen atmosphere. The crude catalyst was then placed in 10wt% hydrogen peroxide and stirred at 60°C for 100 minutes. The catalyst was purified to remove the M2 phase, and then dried at 120°C for 8 hours to obtain the final catalyst product with the molecular formula Mo1V. 0.30 Te 0.18 Nb 0.12 It is denoted as ODHE-14.

[0122] Comparative Example 4

[0123] The catalyst for the oxidative dehydrogenation of ethane provided in this comparative example is similar to that in Example 4, except that the order of addition of the template agent is different. The specific preparation method of the catalyst for the oxidative dehydrogenation of ethane provided in this comparative example includes the following steps:

[0124] (1) A certain amount of ammonium heptamolybdate tetrahydrate, ammonium metavanadate, telluric acid, guar gum powder, and P123 were added to deionized water and stirred at 80°C for 85 minutes to form a mixed solution. The amount of guar gum powder added was 0.04 wt% of the mass of ammonium heptamolybdate tetrahydrate. The amount of polyether P123 added was 0.15 wt% of the mass of ammonium heptamolybdate tetrahydrate.

[0125] (2) Add a certain amount of niobium oxalate to deionized water and stir at 80°C for 30 minutes to form an aqueous solution of niobium oxalate;

[0126] (3) An aqueous solution of niobium oxalate was added dropwise to the mixed solution (over 30 min) to form a suspension. After aging at 80°C for 180 min, it was subjected to hydrothermal crystallization at 180°C for 30 h, and then dried at 80°C for 16 h. The catalyst was calcined at 300°C for 4 h in air, and then calcined at 620°C for 2 h in nitrogen atmosphere. The crude catalyst was then placed in 10 wt% hydrogen peroxide solution and stirred at 60°C for 100 min. The catalyst was purified to remove the M2 phase, and then dried at 120°C for 8 h to obtain the final catalyst product with the molecular formula Mo1V. 0.30 Te 0.18 Nb 0.12 It is denoted as ODHE-15.

[0127] Comparative Example 5

[0128] The catalyst for the oxidative dehydrogenation of ethane provided in this comparative example is similar to that in Example 4, except that the niobium oxalate solution is added at a different time. The specific preparation method of the catalyst for the oxidative dehydrogenation of ethane provided in this comparative example includes the following steps:

[0129] (1) Add a certain amount of ammonium heptamolybdate tetrahydrate, ammonium metavanadate, telluric acid and guar gum powder to deionized water, stir at 80°C for 85 min to form a mixed solution. The amount of guar gum powder added is 0.04 wt% of the mass of ammonium heptamolybdate tetrahydrate.

[0130] (2) Add polyether p123 to deionized water and stir at 100°C for 200 min to obtain an aqueous solution of polyether p123; the amount of polyether p123 added is 0.15 wt% of the mass of ammonium heptamolybdate tetrahydrate.

[0131] (3) Add a certain amount of niobium oxalate to deionized water and stir at 80°C for 30 minutes to form an aqueous solution of niobium oxalate;

[0132] (4) Add an aqueous solution of niobium oxalate dropwise to the mixed solution (takes 5 min) to form a suspension. Then add an aqueous solution of polyether p123. After aging at 80°C for 180 min, perform hydrothermal crystallization at 180°C for 30 h, and then dry at 80°C for 16 h. Calcinate at 300°C in air for 4 h, and then calcine at 620°C in nitrogen for 2 h. Place the crude catalyst in 10 wt% hydrogen peroxide solution and stir at 60°C for 100 min. Purify the catalyst to remove the M2 phase, and then dry at 120°C for 8 h to obtain the final catalyst product with the molecular formula Mo1V. 0.30 Te 0.18 Nb 0.12 It is denoted as ODHE-16.

[0133] Comparative Example 6

[0134] The catalyst for the oxidative dehydrogenation of ethane provided in this comparative example is similar to that in Example 4, except that a different template agent is used. The specific preparation method of the catalyst for the oxidative dehydrogenation of ethane provided in this comparative example includes the following steps:

[0135] (1) Add a certain amount of ammonium heptamolybdate tetrahydrate, ammonium metavanadate, telluric acid and guar gum powder to deionized water, stir at 80°C for 85 min to form a mixed solution. The amount of guar gum powder added is 0.04 wt% of the mass of ammonium heptamolybdate tetrahydrate.

[0136] (2) Add hexadecyltrimethylammonium bromide to deionized water and stir at 60°C for 60 min to obtain an aqueous solution of hexadecyltrimethylammonium bromide; the amount of hexadecyltrimethylammonium bromide added is 0.15 wt% of the mass of ammonium heptamolybdate tetrahydrate.

[0137] (3) Add a certain amount of niobium oxalate to deionized water and stir at 80°C for 30 minutes to form an aqueous solution of niobium oxalate;

[0138] (4) Niobium oxalate aqueous solution was added dropwise to the mixed solution (takes 30 min) to form a suspension. Then, hexadecyltrimethylammonium bromide aqueous solution was added. After aging at 80℃ for 180 min, hydrothermal crystallization was carried out at 180℃ for 30 h, followed by drying at 80℃ for 16 h. The catalyst was calcined at 300℃ for 4 h in air atmosphere, and then calcined at 620℃ for 2 h in nitrogen atmosphere. The crude catalyst was placed in 10 wt% hydrogen peroxide and stirred at 60℃ for 100 min. The catalyst was purified to remove the M2 phase, and then dried at 120℃ for 8 h to obtain the final catalyst product with the molecular formula Mo1V. 0.30 Te 0.18 Nb 0.12 It is denoted as ODHE-16.

[0139] Catalyst evaluation results

[0140] The catalysts prepared in the above embodiments and comparative examples were subjected to performance tests according to the aforementioned performance evaluation and analysis methods. The specific results are shown in the table below.

[0141] Table 1

[0142]

[0143]

[0144] As shown in the table above, compared with the prior art, the catalyst prepared by the method of this invention exhibits excellent catalytic performance when used in the oxidative dehydrogenation reaction of ethane. Specifically, comparing Example 4 with Comparative Example 1, it can be seen that the reaction performance of the prepared catalyst is significantly improved after adding dispersant and template agent. This is mainly because the addition of dispersant and template agent during the preparation process disperses and supports the active components, thereby improving the pore structure and specific surface area of ​​the catalyst and enhancing its catalytic activity. Conversely, the reaction performance of catalysts prepared by adding dispersant alone (Comparative Example 2) and template agent alone (Comparative Example 3) is significantly reduced, indicating that the dispersant and template agent work synergistically during catalyst preparation, significantly improving the reaction performance of the catalyst.

[0145] As can be seen from the comparison between Example 4 and Comparative Example 4, the reaction performance of the catalyst prepared after adding the template agent during the aging stage is significantly improved. This is mainly because the catalyst forms an ordered pore structure, resulting in an increased specific surface area. However, the reaction performance of the catalyst is poor when the template agent is added in the initial stage. This is mainly because Mo, V, and Te interact to form Anderson-type heteropolycationic complexes in the initial stage. Adding an organic template agent at this stage will interfere with or even destroy the formation of this microstructure, thereby affecting the formation of the active phase of the catalyst and resulting in poor catalyst reaction performance.

[0146] As can be seen from the comparison between Example 4 and Comparative Example 5, the catalyst prepared by shortening the dropping time of niobium oxalate solution has poor reaction performance. This is mainly because the niobium oxalate solution is added too quickly, which affects the formation of active species, resulting in a reduction of the active phase in the catalyst and a decrease in catalyst performance.

[0147] As shown in Example 4 compared to Comparative Example 6, while the addition of hexadecyltrimethylammonium bromide can improve the catalyst's reactivity to some extent, the effect of the organic template agent polyether p123 is more pronounced. This is mainly because polyether p123, as an organic template agent, can be used to prepare a mesoporous MoVTeNb catalyst in situ through solvent evaporation-induced self-assembly, significantly improving the catalyst's specific surface area, pore volume, and pore size. In summary, the addition of both dispersants and template agents greatly improves the catalyst's physical properties and reactivity, but the order in which the template agents are added is crucial.

[0148] Of course, the present invention may have other various embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications according to the present invention, but these corresponding changes and modifications should all fall within the protection scope of the claims of the present invention.

Claims

1. A method for preparing a catalyst for the oxidative dehydrogenation reaction of ethane, characterized in that, Includes the following steps: (1) Dissolve ammonium heptamolybdate tetrahydrate, ammonium metavanadate, telluric acid and dispersant in deionized water to form a mixed solution; (2) Niobium oxalate aqueous solution is added to the mixed solution within 15~50 min to form a suspension, and then an aqueous solution of template agent polyether P123 is added. After aging, hydrothermal crystallization reaction, drying, calcination and removal of M2 phase, the catalyst for ethane oxidative dehydrogenation reaction is obtained. The dispersant is selected from any one of propylene glycol, polymethyl cellulose, polyvinyl alcohol, guar gum, polyethylene glycol, and polyvinylpyrrolidone; The amount of the dispersant added is 0.005 wt% to 0.1 wt% of the mass of the ammonium heptamolybdate tetrahydrate; The amount of the template agent polyether P123 added is 0.01wt%~0.3wt% of the mass of the ammonium heptamolybdate tetrahydrate; The catalyst used for the oxidative dehydrogenation reaction of ethane has the following general formula: Mo a V b Te c Nb d Where a=1, b is 0.25~0.32, c is 0.16~0.23, and d is 0.08~0.

15.

2. The preparation method according to claim 1, characterized in that, The aging temperature is 20~90℃ and the time is 20~180min.

3. The preparation method according to claim 1, characterized in that, The hydrothermal crystallization reaction is carried out at a temperature of 150~200℃ for a time of 12~60h.

4. The preparation method according to claim 1, characterized in that, The drying temperature is 70~120℃, and the time is 6~20h.

5. The preparation method according to claim 1, characterized in that, The roasting process is selected from two-stage roasting.

6. The preparation method according to claim 5, characterized in that, The two-stage calcination process includes first calcining in air at 200-400°C for 2-6 hours, and then calcining in an inert atmosphere at 550-650°C for 1-4 hours.

7. The preparation method according to claim 1, characterized in that, The M2 phase is removed by purification with hydrogen peroxide, wherein the concentration of hydrogen peroxide is 5wt%~15wt%, the purification temperature is 30~80℃, and the time is 30~240min.

8. A catalyst for the oxidative dehydrogenation of ethane prepared by the method for preparing the catalyst for the oxidative dehydrogenation reaction of ethane according to any one of claims 1-7, characterized in that, The catalyst used for the oxidative dehydrogenation reaction of ethane has the following general formula: Mo a V b Te c Nb d Where a=1, b is 0.25~0.32, c is 0.16~0.23, and d is 0.08~0.15.

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