Ethylbenzene dehydrogenation catalyst, preparation method and application thereof

Abstract

This invention relates to an ethylbenzene dehydrogenation catalyst, its preparation method, and its applications. The catalyst comprises oxides of Fe₂O₃, K₂O, CeO₂, MoO₃, CaO, and RE, wherein RE includes at least one selected from Dy, Yb, and Lu; and the average grain size of CeO₂ is less than or equal to 30 nm. This catalyst exhibits high activity, styrene selectivity, and good stability in the ethylbenzene dehydrogenation reaction at low water ratios.

Description

Technical Field

[0001] This invention relates to an ethylbenzene dehydrogenation catalyst, its preparation method, and its application, specifically to a catalyst for the dehydrogenation of ethylbenzene to styrene with a low water ratio, its preparation method, and its application. Background Technology

[0002] Styrene is an important bulk chemical raw material that plays a vital role in the national economy. The demand for styrene is extremely widespread. Its direct downstream applications include EPS (expandable polystyrene), PS (polystyrene), and ABS (acrylonitrile-butadiene-styrene), accounting for 71% of total downstream demand. End products include electronics, foam packaging, sheet materials, building materials, and household appliances, among many other fields.

[0003] Currently, there are two main methods in the world for producing styrene from ethylbenzene: one is the catalytic dehydrogenation of ethylbenzene to produce hydrogen and styrene, and the other is the PO / SM co-oxidation method. The catalytic dehydrogenation of ethylbenzene has always been the dominant technology for styrene production, accounting for more than 85% of the total styrene production capacity.

[0004] Ethylbenzene dehydrogenation is a strongly endothermic and reversible reaction involving an increase in the number of molecules, favored by high temperature and low pressure. Industrially, large amounts of high-temperature steam are typically introduced to promote the formation of the target product, styrene. Steam plays several important roles in the reaction: providing the heat required for the reaction; reducing the partial pressure of ethylbenzene, thus shifting the chemical equilibrium towards styrene; eliminating carbon buildup on the catalyst surface through a water-gas shift reaction; and oxidizing the catalyst surface to maintain its activity. However, using large amounts of superheated steam as the dehydrogenation medium results in high energy consumption, large product condensation, high equipment costs, and high production costs. Therefore, the ethylbenzene dehydrogenation process aims to achieve a high styrene yield with a low water ratio (the mass ratio of steam to ethylbenzene in the feed). Adopting a low water ratio operation is a crucial measure for energy conservation and cost reduction. Developing styrene catalysts suitable for low water ratios and improving their activity, selectivity, and stability to achieve energy conservation, cost reduction, and lower production costs in styrene plants has become an urgent need for styrene enterprises.

[0005] Most existing ethylbenzene dehydrogenation catalysts are Fe-K-Ce based, with Fe-K oxides as the main catalyst and Ce as the main promoter. They also contain structural stabilizers and electronic promoters such as oxides of Mg, Mo, W, and Ca. Currently disclosed low-water-ratio ethylbenzene dehydrogenation catalysts mainly improve their activity and stability under low-water-ratio conditions by enhancing catalyst structural stability and modifying catalyst surface properties. Rare earth elements are strategic resources, and with the increasing national emphasis on rare earth protection, improving Ce utilization efficiency and reducing Ce usage in catalysts is also an important direction for catalyst research and development.

[0006] CN106582678A discloses a method for stabilizing the active phase of a Fe-K-Ce-W catalyst by introducing Ba, Sn, and rare earth oxides (Sm, Eu, Gd). CN1981929A discloses a method for improving the stability and activity of a low-K catalyst under low water ratio conditions by adding at least two light rare earth oxide promoters (selected from La, Pr, Nd, and Sm) other than cerium to a Fe-K-Ce-W catalyst system, and simultaneously adding at least one metal oxide selected from Ca, Mg, Ba, B, Sn, Pb, Cu, Zn, Ti, Zr, or Mo.

[0007] The catalysts reported above exhibited varying degrees of low activity and poor stability when applied to ethylbenzene dehydrogenation reactions under low water ratio conditions. Current styrene production technology is trending towards larger-scale plants and more comprehensive energy utilization. Developing an ethylbenzene dehydrogenation catalyst suitable for operation under low water ratio conditions, with higher activity and better stability, has been a continuous research focus. Summary of the Invention

[0008] The technical problem this invention aims to solve is the low activity and poor stability of catalysts in existing ethylbenzene dehydrogenation technologies under low water ratio conditions. This invention provides a novel ethylbenzene dehydrogenation catalyst, its preparation method, and its applications. This catalyst exhibits high activity, styrene selectivity, and good stability in the ethylbenzene dehydrogenation reaction under low water ratio conditions.

[0009] The first aspect of the present invention provides an ethylbenzene dehydrogenation catalyst, the catalyst comprising oxides of Fe2O3, K2O, CeO2, MoO3, CaO and RE, wherein RE includes at least one selected from Dy, Yb and Lu; and the average grain size of CeO2 is less than or equal to 30 nm.

[0010] In the above technical solution, the average grain size of CeO2 in the catalyst is less than or equal to 30 nm, preferably 10 to 30 nm, and more preferably 10 to 25 nm.

[0011] In the above technical solution, the catalyst, based on the total mass of the catalyst, comprises the following components by mass fraction:

[0012] (a) 60%–86% Fe2O3;

[0013] (b) 8%–17% K₂O;

[0014] (c) 4%–11% CeO2;

[0015] (d) 0.5%–5% MoO3;

[0016] (e) 0.2%–4% CaO;

[0017] (f) 0.1% to 3% of RE oxides;

[0018] RE includes at least one selected from Dy, Yb and Lu.

[0019] In the above technical solution, preferably, RE includes at least one selected from Yb and Lu;

[0020] In the above technical solution, preferably, RE includes Yb and Lu; wherein, the weight ratio of Yb and Lu, calculated as oxides, is 0.1 to 1. Yb and Lu have a synergistic effect, which improves the activity, styrene selectivity, and stability of the catalyst in the ethylbenzene dehydrogenation reaction at a low water ratio.

[0021] A second aspect of the present invention provides a method for preparing the above-mentioned ethylbenzene dehydrogenation catalyst, the method comprising the following steps:

[0022] The Fe source, K source, Ce source, Mo source, Ca source, RE source, and optional porogen are mixed evenly, kneaded, and calcined to obtain the catalyst.

[0023] In the above technical solution, no binder is added during the preparation process.

[0024] In the above technical solution, an appropriate amount of water can be added during the kneading process. The water is added slowly, and the amount is not particularly limited; it can be adjusted according to the dryness or wetness of the material. Generally, the amount of water added accounts for 15% to 35% of the mass of the catalyst raw material.

[0025] In the above technical solution, the molding can be carried out by extrusion molding, and the strip shape can be a particle with a diameter of 2 to 5 mm and a length of 3 to 10 mm.

[0026] In the above technical solution, the calcination conditions are as follows: the calcination temperature is 900–1100℃, and the calcination time is 0.5–4 hours. The calcination is a high-temperature rapid calcination.

[0027] In the above technical solution, the preferred calcination conditions are as follows: calcination temperature is 950-1050℃, and calcination time is 1-3h.

[0028] In the above technical solution, the shaped material can undergo a drying step before calcination. The drying temperature is 30–200℃, and the drying time is 1–24 hours.

[0029] In the above technical solution, the Fe source is added in the form of Fe2O3 oxide. The Fe source is preferably iron oxide red and / or iron oxide yellow, more preferably a combination of iron oxide red and iron oxide yellow. The K source is added in the form of a potassium salt; the potassium salt is selected from any one or more of potassium carbonate, potassium nitrate, and potassium bicarbonate. The Ce source is added in the form of a cerium salt; the cerium salt is any one or more of cerium nitrate, cerium oxalate, and cerium carbonate. The Mo source is added in the form of a molybdenum salt or oxide, the molybdenum salt being ammonium molybdate; the Ca source is added in the form of an oxide or hydroxide; the RE source is added in the form of a nitrate or chloride. The pore-forming agent is any one or more of activated carbon, graphite, sodium carboxymethyl cellulose, and polystyrene microspheres. The amount of the pore-forming agent added is 0.01% to 5% of the catalyst mass.

[0030] A third aspect of the present invention provides the application of the above-described catalyst or the catalyst prepared by the above-described method in the dehydrogenation of ethylbenzene to styrene.

[0031] In the above technical solution, the method of application is as follows: the ethylbenzene-containing raw material is contacted with the catalyst of the present invention in the presence of water vapor to carry out a dehydrogenation reaction to obtain a styrene-containing product.

[0032] In the above technical solution, the application of the ethylbenzene dehydrogenation catalyst in the preparation of styrene is suitable for ethylbenzene dehydrogenation at a low water ratio; the low water ratio is below 1.2, preferably 0.7 to 1.2. The low water ratio is a weight ratio.

[0033] In the above technical solution, the water is preheated into water vapor before entering the reactor and then fully mixed with the raw material gas.

[0034] In the above technical solution, the temperature of the dehydrogenation reaction is 570–640°C.

[0035] In the above technical solution, the pressure of the dehydrogenation reaction is an absolute pressure, 20-100 kPa.

[0036] In the above technical solution, the mass hourly space velocity (MSV) of ethylbenzene is 0.2–2.0 h⁻¹. -1 .

[0037] Compared with the prior art, the present invention has significant advantages and outstanding effects, as follows:

[0038] 1. The inventors discovered that the reactivity and stability of the Fe-K-Ce ethylbenzene dehydrogenation catalyst are highly correlated with the CeO2 crystallite size within the catalyst. Small CeO2 crystallites fully expose the active sites, significantly improving the catalyst's activity. Simultaneously, during use, the gradual growth of CeO2 crystals affects the catalyst's activity, while stable CeO2 crystals enhance its stability. Further research revealed that adding Dy, Yb, and Lu promoters to the catalyst effectively limits the CeO2 crystallite size and inhibits CeO2 crystal growth during use. This is likely due to the formation of Ce-O-RE bonds, which suppress CeO2 crystal growth during catalyst preparation and use. Small CeO2 crystallites improve Ce utilization efficiency and catalyst activity, while also exhibiting good stability.

[0039] In this invention, the inventors selected at least one of the specific additives Dy, Yb, and Lu, which not only have the function of regulating the crystal structure of CeO2, but also improve the selectivity of styrene while improving the activity and stability of the catalyst.

[0040] 2. In this invention, the inventors discovered that rapid high-temperature calcination during the preparation of the Fe-K-Ce ethylbenzene dehydrogenation catalyst facilitates the rapid crystallization of CeO2, which is beneficial for obtaining small crystallites and further improves the controllability of CeO2 crystallite size adjustment. Compared with conventional preparation methods, this method is more conducive to improving the catalytic performance of the ethylbenzene dehydrogenation catalyst. The catalyst preparation process is simple, and the resulting catalyst has the advantages of high activity, high styrene selectivity, and stable performance after 1000 hours of operation.

[0041] 3. The catalyst of this invention is used in the dehydrogenation reaction of ethylbenzene to styrene. It exhibits high activity, high selectivity and high stability under different water ratios, especially at low water ratios, and has achieved good technical results.

[0042] Using the technical solution of this invention, the catalyst of this invention is evaluated for activity in an isothermal fixed bed at 60 kPa (absolute pressure) and ethylbenzene mass hourly space velocity (MHSV) of 1.0 h⁻¹. -1 The catalyst was evaluated at 605℃ under conditions where the water ratio was reduced from the usual 2.0 (by weight) to 0.8 (by weight). After 100 hours of reaction, the ethylbenzene conversion reached over 76%, and the styrene selectivity reached over 96%. After 1000 hours of operation, there was no significant change in catalyst activity and styrene selectivity, indicating good catalyst stability. This demonstrates that the catalyst of this invention, when used in the dehydrogenation of ethylbenzene to styrene, especially under low water ratio conditions, exhibits high activity, styrene selectivity, and stability, achieving excellent technical results. Attached Figure Description

[0043] Figure 1 The images show the XRD patterns of the catalysts in Example 1 and Comparative Example 1. Detailed Implementation

[0044] The present invention will be further illustrated by the following embodiments, but the scope of protection of the present invention is not limited by the embodiments.

[0045] In this invention, XRD was performed using a Rigaku Ultima IV X-ray powder diffractometer from Japan, with a Cu-Kα ray source (λ = 0.15406 nm), a nickel filter, an operating voltage of 35 kV, a current of 25 mA, and a scanning rate of 2° / min.

[0046] In this invention, the average grain size of CeO2 is calculated based on the X-ray diffraction pattern and the Scherrer equation. The average grain size of CeO2 is calculated based on the diffraction peak of the CeO2(111) crystal plane in the X-ray diffraction pattern, specifically the diffraction peak at position 2θ = 28.50 ± 0.15°, and the Scherrer equation. The Scherrer equation, D = Kλ / βcosθ, describes the relationship between the average grain size and the half-maximum width (WHM) of the diffraction peak in the XRD pattern. In the equation, D is the average size of the grain perpendicular to the crystal plane, K is the Scherrer constant, λ is the X-ray wavelength, β is the measured WHM of the diffraction peak in the sample, and θ is the Bragg diffraction angle.

[0047] In this invention, the performance of the catalyst for the ethylbenzene dehydrogenation reaction is evaluated in an isothermal fixed bed. The process is briefly described below:

[0048] The reactor is a 1” stainless steel tube filled with 50–150 mL of catalyst with a diameter of 3–10 mm. Deionized water and ethylbenzene are separately metered into a preheating mixer, preheated and mixed into a gaseous state before entering the reactor. The reactor is heated by an electric heating wire to reach a predetermined temperature. The reactants flowing out of the reactor are condensed in water and their composition is analyzed by gas chromatography.

[0049] Ethylbenzene conversion and styrene selectivity are calculated using the following formulas:

[0050]

[0051]

[0052]

Example 1

[0053] Weigh out the following amounts: iron oxide red (equivalent to 48.5 parts Fe₂O₃), iron oxide yellow (equivalent to 23.2 parts Fe₂O₃), potassium carbonate (equivalent to 13.2 parts K₂O), cerium nitrate (equivalent to 9.6 parts CeO₂), ammonium molybdate (equivalent to 3.2 parts MoO₃), calcium hydroxide (equivalent to 1.8 parts CaO), ytterbium nitrate (equivalent to 0.2 parts Yb₂O₃), lutetium nitrate (equivalent to 0.3 parts Lu₂O₃), and sodium carboxymethyl cellulose (equivalent to 1.8 parts). Stir in a mixer for 2 hours until homogeneous. Then add deionized water (equivalent to 24% of the total weight of the dehydrogenation catalyst raw materials) and mix for 2 hours. Next, extrude and granulate the mixture to obtain particles with a diameter of 3 mm and a length of 6 mm. Place these particles in an oven and dry at 80°C for 4 hours, then at 160°C for 4 hours. Finally, calcine them in a muffle furnace at 1000°C for 1.5 hours to obtain the finished dehydrogenation catalyst. The composition of the dehydrogenation catalyst is listed in Table 1. The XRD pattern of the dehydrogenation catalyst is shown in [Table 1]. Figure 1 .

[0054] 100 mL of dehydrogenation catalyst was loaded into the reactor and incubated at 60 kPa (absolute pressure) and a mass hourly space velocity (WHSV) of 1.0 h⁻¹ for ethylbenzene. -1 The performance was evaluated under the conditions of reaction temperature 605℃ and water ratio 0.8 (wt). The test results after 100h of reaction are listed in Table 1, and the test results after 1000h of reaction are listed in Table 2.

[0055]

Example 2

[0056] Weigh out the following amounts: 38.2 parts of iron oxide red (Fe₂O₃), 23.7 parts of iron oxide yellow (Fe₂O₃), 16.8 parts of potassium carbonate (K₂O), 10.8 parts of cerium nitrate (CeO₂), 4.9 parts of ammonium molybdate (MoO₃), 2.9 parts of calcium hydroxide (CaO), 0.8 parts of ytterbium nitrate (Yb₂O₃), 1.9 parts of lutetium nitrate (Lu₂O₃), and 1.6 parts of sodium carboxymethyl cellulose. Stir in a mixer for 2 hours until homogeneous. Then add 24% (by weight) of deionized water (based on the total weight of the dehydrogenation catalyst raw materials) and mix for 2 hours. Next, extrude and granulate the mixture to obtain particles with a diameter of 3 mm and a length of 6 mm. Place these particles in an oven and dry at 80°C for 4 hours, then at 160°C for 4 hours. Finally, calcine them in a muffle furnace at 1000°C for 1.5 hours to obtain the finished dehydrogenation catalyst. The composition of the dehydrogenation catalyst is listed in Table 1.

[0057] 100 mL of dehydrogenation catalyst was loaded into the reactor and incubated at 60 kPa (absolute pressure) and a mass hourly space velocity (WHSV) of 1.0 h⁻¹ for ethylbenzene. -1 The performance was evaluated under the conditions of reaction temperature 605℃ and water ratio 0.8 (wt). The test results after 100h of reaction are listed in Table 1.

[0058]

Example 3

[0059] Weigh out the following amounts: 48.2 parts of iron oxide red (Fe₂O₃), 21.9 parts of iron oxide yellow (Fe₂O₃), 14.2 parts of potassium carbonate (K₂O), 10.3 parts of cerium nitrate (CeO₂), 3.6 parts of ammonium molybdate (MoO₃), 1.6 parts of calcium hydroxide (CaO), 0.1 parts of ytterbium nitrate (Yb₂O₃), 0.1 parts of lutetium nitrate (Lu₂O₃), and 0.2 parts of sodium carboxymethyl cellulose. Stir in a mixer for 2 hours until homogeneous. Then add 24% (by weight) of deionized water (based on the total weight of the dehydrogenation catalyst raw materials) and mix for 2 hours. Next, extrude and granulate the mixture to obtain particles with a diameter of 3 mm and a length of 6 mm. Place these particles in an oven and dry at 80°C for 4 hours, then at 160°C for 4 hours. Finally, calcine them in a muffle furnace at 1000°C for 1.5 hours to obtain the finished dehydrogenation catalyst. The composition of the dehydrogenation catalyst is listed in Table 1.

[0060] 100 mL of dehydrogenation catalyst was loaded into the reactor and incubated at 60 kPa (absolute pressure) and a mass hourly space velocity (WHSV) of 1.0 h⁻¹ for ethylbenzene. -1 The performance was evaluated under the conditions of reaction temperature 605℃ and water ratio 0.8 (wt). The test results after 100h of reaction are listed in Table 1.

[0061]

Example 4

[0062] Weigh out the following amounts: 55.6 parts of iron oxide red (Fe₂O₃), 29.4 parts of iron oxide yellow (Fe₂O₃), 8.3 parts of potassium carbonate (K₂O), 4.6 parts of cerium nitrate (CeO₂), 1.2 parts of ammonium molybdate (MoO₃), 0.5 parts of calcium hydroxide (CaO), 0.2 parts of ytterbium nitrate (Yb₂O₃), 0.2 parts of lutetium nitrate (Lu₂O₃), and 4.2 parts of sodium carboxymethyl cellulose. Stir in a mixer for 2 hours until homogeneous. Then add 24% (by weight) of deionized water (based on the total weight of the dehydrogenation catalyst raw materials) and mix for 2 hours. Next, extrude and granulate the mixture to obtain particles with a diameter of 3 mm and a length of 6 mm. Dry these particles in an oven at 80°C for 4 hours, then at 160°C for 4 hours. Finally, calcine them in a muffle furnace at 1000°C for 1.5 hours to obtain the finished dehydrogenation catalyst. The composition of the dehydrogenation catalyst is listed in Table 1.

[0063] 100 mL of dehydrogenation catalyst was loaded into the reactor and incubated at 60 kPa (absolute pressure) and a mass hourly space velocity (WHSV) of 1.0 h⁻¹ for ethylbenzene. -1 The performance was evaluated under the conditions of reaction temperature 605℃ and water ratio 0.8 (wt). The test results after 100h of reaction are listed in Table 1.

[0064]

Example 5

[0065] Weigh out the following amounts: iron oxide red (equivalent to 46.3 parts Fe2O3), iron oxide yellow (equivalent to 23.3 parts Fe2O3), potassium carbonate (equivalent to 15.4 parts K2O), cerium nitrate (equivalent to 9.9 parts CeO2), ammonium molybdate (equivalent to 0.6 parts MoO3), calcium hydroxide (equivalent to 2.8 parts CaO), ytterbium nitrate (equivalent to 0.8 parts Yb2O3), lutetium nitrate (equivalent to 0.9 parts Lu2O3), and sodium carboxymethyl cellulose (equivalent to 2.1 parts). Stir in a mixer for 2 hours until homogeneous. Then add deionized water (equivalent to 24% of the total weight of the dehydrogenation catalyst raw materials) and mix for 2 hours. Next, extrude and granulate the above mixture to obtain particles with a diameter of 3 mm and a length of 6 mm. Place them in an oven and dry at 80°C for 4 hours, then at 160°C for 4 hours. Finally, place them in a muffle furnace and calcine at 1000°C for 1.5 hours to obtain the finished dehydrogenation catalyst. The composition of the dehydrogenation catalyst is listed in Table 1.

[0066] 100 mL of dehydrogenation catalyst was loaded into the reactor and incubated at 60 kPa (absolute pressure) and a mass hourly space velocity (WHSV) of 1.0 h⁻¹ for ethylbenzene. -1 The performance was evaluated under the conditions of reaction temperature 605℃ and water ratio 0.8 (wt). The test results after 100h of reaction are listed in Table 1, and the test results after 1000h of reaction are listed in Table 2.

[0067]

Example 6

[0068] Weigh out the following amounts: 47.1 parts of iron oxide red (Fe₂O₃), 24.6 parts of iron oxide yellow (Fe₂O₃), 12.8 parts of potassium carbonate (K₂O), 10.4 parts of cerium nitrate (CeO₂), 3.6 parts of ammonium molybdate (MoO₃), 0.2 parts of calcium hydroxide (CaO), 1.3 parts of ytterbium nitrate (Yb₂O₃), and 1.4 parts of sodium carboxymethyl cellulose. Stir in a mixer for 2 hours until homogeneous. Then add 24% (by weight) of deionized water (based on the total weight of the dehydrogenation catalyst raw materials) and mix for 2 hours. Next, extrude and granulate the mixture to obtain particles with a diameter of 3 mm and a length of 6 mm. Place these particles in an oven and dry at 80°C for 4 hours, then at 160°C for 4 hours. Finally, calcine them in a muffle furnace at 1000°C for 1.5 hours to obtain the finished dehydrogenation catalyst. The composition of the dehydrogenation catalyst is listed in Table 1.

[0069] 100 mL of dehydrogenation catalyst was loaded into the reactor and incubated at 60 kPa (absolute pressure) and a mass hourly space velocity (WHSV) of 1.0 h⁻¹ for ethylbenzene. -1 The performance was evaluated under the conditions of reaction temperature 605℃ and water ratio 0.8 (wt). The test results after 100h of reaction are listed in Table 1.

[0070]

Example 7

[0071] Weigh out the following amounts: 46.9 parts of iron oxide red (Fe₂O₃), 23.9 parts of iron oxide yellow (Fe₂O₃), 10.7 parts of potassium carbonate (K₂O), 10.0 parts of cerium nitrate (CeO₂), 3.2 parts of ammonium molybdate (MoO₃), 2.6 parts of calcium hydroxide (CaO), 2.1 parts of ytterbium nitrate (Yb₂O₃), 0.6 parts of lutetium nitrate (Lu₂O₃), and 2.2 parts of sodium carboxymethyl cellulose. Stir in a mixer for 2 hours until homogeneous. Then add 24% (by weight of the total raw materials for the dehydrogenation catalyst) of deionized water and mix for 2 hours. Next, extrude and granulate the mixture to obtain particles with a diameter of 3 mm and a length of 6 mm. Place the particles in an oven and dry at 80°C for 4 hours, then at 160°C for 4 hours. Finally, calcine them in a muffle furnace at 1000°C for 1.5 hours to obtain the finished dehydrogenation catalyst. The composition of the dehydrogenation catalyst is listed in Table 1.

[0072] 100 mL of dehydrogenation catalyst was loaded into the reactor and incubated at 60 kPa (absolute pressure) and a mass hourly space velocity (WHSV) of 1.0 h⁻¹ for ethylbenzene. -1 The performance was evaluated under the conditions of reaction temperature 605℃ and water ratio 0.8 (wt). The test results after 100h of reaction are listed in Table 1.

[0073]

Example 8

[0074] Weigh out the following amounts: 48.5 parts of iron oxide red (Fe₂O₃), 23.2 parts of iron oxide yellow (Fe₂O₃), 13.2 parts of potassium nitrate (K₂O), 9.6 parts of cerium nitrate (CeO₂), 3.2 parts of MoO₃, 1.8 parts of calcium hydroxide (CaO), 0.5 parts of dysprosium nitrate (Dy₂O₃), and 1.8 parts of sodium carboxymethyl cellulose. Stir in a mixer for 2 hours until homogeneous. Then add 24% (by weight) of deionized water (based on the total weight of the dehydrogenation catalyst raw materials) and mix for 2 hours. Next, extrude and granulate the mixture to obtain particles with a diameter of 3 mm and a length of 6 mm. Place these particles in an oven and dry at 80°C for 4 hours, then at 160°C for 4 hours. Finally, calcine them in a muffle furnace at 1000°C for 1.5 hours to obtain the finished dehydrogenation catalyst. The composition of the dehydrogenation catalyst is listed in Table 1.

[0075] 100 mL of dehydrogenation catalyst was loaded into the reactor and incubated at 60 kPa (absolute pressure) and a mass hourly space velocity (WHSV) of 1.0 h⁻¹ for ethylbenzene. -1 The performance was evaluated under the conditions of reaction temperature 605℃ and water ratio 0.8 (wt). The test results after 100h of reaction are listed in Table 1.

[0076]

Example 9

[0077] Weigh out the following amounts: 48.5 parts of iron oxide red (Fe₂O₃), 23.2 parts of iron oxide yellow (Fe₂O₃), 13.2 parts of potassium bicarbonate (K₂O), 9.6 parts of cerium nitrate (CeO₂), 3.2 parts of ammonium molybdate (MoO₃), 1.8 parts of CaO, 0.5 parts of lutetium nitrate (Lu₂O₃), and 1.8 parts of sodium carboxymethyl cellulose. Stir in a mixer for 2 hours until homogeneous. Then add 24% (by weight) of deionized water (based on the total weight of the dehydrogenation catalyst raw materials) and mix for 2 hours. Next, extrude and granulate the mixture to obtain particles with a diameter of 3 mm and a length of 6 mm. Place these particles in an oven and dry at 80°C for 4 hours, then at 160°C for 4 hours. Finally, calcine them in a muffle furnace at 900°C for 2 hours to obtain the finished dehydrogenation catalyst. The composition of the dehydrogenation catalyst is listed in Table 1.

[0078] 100 mL of dehydrogenation catalyst was loaded into the reactor and incubated at 60 kPa (absolute pressure) and a mass hourly space velocity (WHSV) of 1.0 h⁻¹ for ethylbenzene. -1 The performance was evaluated under the conditions of reaction temperature 605℃ and water ratio 0.8 (wt). The test results after 100h of reaction are listed in Table 1.

[0079]

Example 10

[0080] Weigh out the following amounts: 48.5 parts of iron oxide red (Fe₂O₃), 23.2 parts of iron oxide yellow (Fe₂O₃), 13.2 parts of potassium carbonate (K₂O), 9.6 parts of cerium oxalate (CeO₂), 3.2 parts of ammonium molybdate (MoO₃), 1.8 parts of calcium hydroxide (CaO), 0.2 parts of ytterbium nitrate (Yb₂O₃), 0.3 parts of lutetium nitrate (Lu₂O₃), and 1.8 parts of graphite. Stir in a mixer for 2 hours until homogeneous. Then add 24% (by weight) of deionized water (based on the total weight of the dehydrogenation catalyst raw materials) and mix for 2 hours. Next, extrude and granulate the mixture to obtain particles with a diameter of 3 mm and a length of 6 mm. Place these particles in an oven and dry at 80°C for 4 hours, then at 160°C for 4 hours. Finally, calcine them in a muffle furnace at 950°C for 1.8 hours to obtain the finished dehydrogenation catalyst. The composition of the dehydrogenation catalyst is listed in Table 1.

[0081] 100 mL of dehydrogenation catalyst was loaded into the reactor and incubated at 60 kPa (absolute pressure) and a mass hourly space velocity (WHSV) of 1.0 h⁻¹ for ethylbenzene. -1 The performance was evaluated under the conditions of reaction temperature 605℃ and water ratio 0.8 (wt). The test results after 100h of reaction are listed in Table 1, and the test results after 1000h of reaction are listed in Table 2.

[0082]

Example 11

[0083] Weigh out the following amounts: 48.5 parts of iron oxide red (Fe₂O₃), 23.2 parts of iron oxide yellow (Fe₂O₃), 13.2 parts of potassium carbonate (K₂O), 9.6 parts of cerium carbonate (CeO₂), 3.2 parts of ammonium molybdate (MoO₃), 1.8 parts of calcium hydroxide (CaO), 0.2 parts of ytterbium nitrate (Yb₂O₃), 0.3 parts of lutetium nitrate (Lu₂O₃), and 1.8 parts of activated carbon. Stir in a mixer for 2 hours until homogeneous. Then add 24% (by weight) of deionized water (based on the total weight of the dehydrogenation catalyst raw materials) and mix for 2 hours. Next, extrude and granulate the mixture to obtain particles with a diameter of 3 mm and a length of 6 mm. Place these particles in an oven and dry at 80°C for 4 hours, then at 160°C for 4 hours. Finally, calcine them in a muffle furnace at 1050°C for 1 hour to obtain the finished dehydrogenation catalyst. The composition of the dehydrogenation catalyst is listed in Table 1.

[0084] 100 mL of dehydrogenation catalyst was loaded into the reactor and incubated at 60 kPa (absolute pressure) and a mass hourly space velocity (WHSV) of 1.0 h⁻¹ for ethylbenzene. -1 The performance was evaluated under the conditions of reaction temperature 605℃ and water ratio 0.8 (wt). The test results after 100h of reaction are listed in Table 1.

[0085]

Example 12

[0086] Weigh out the following amounts: 48.5 parts of iron oxide red (Fe₂O₃), 23.2 parts of iron oxide yellow (Fe₂O₃), 13.2 parts of potassium carbonate (K₂O), 9.6 parts of cerium nitrate (CeO₂), 3.2 parts of ammonium molybdate (MoO₃), 1.8 parts of calcium hydroxide (CaO), 0.2 parts of ytterbium chloride (Yb₂O₃), 0.3 parts of lutetium chloride (Lu₂O₃), and 1.8 parts of polystyrene microspheres. Stir in a mixer for 2 hours until homogeneous. Then add 24% (by weight) of deionized water (based on the total weight of the dehydrogenation catalyst raw materials) and mix for 2 hours. Next, extrude and granulate the mixture to obtain particles with a diameter of 3 mm and a length of 6 mm. Dry these particles in an oven at 80°C for 4 hours, then at 160°C for 4 hours. Finally, calcine them in a muffle furnace at 1000°C for 1.5 hours to obtain the finished dehydrogenation catalyst. The composition of the dehydrogenation catalyst is listed in Table 1.

[0087] 100 mL of dehydrogenation catalyst was loaded into the reactor and incubated at 60 kPa (absolute pressure) and a mass hourly space velocity (WHSV) of 1.0 h⁻¹ for ethylbenzene. -1 The performance was evaluated under the conditions of reaction temperature 605℃ and water ratio 0.8 (wt). The test results after 100h of reaction are listed in Table 1.

[0088] Comparative Example 1

[0089] Weigh out the following amounts: 48.5 parts of iron oxide red (Fe₂O₃), 23.2 parts of iron oxide yellow (Fe₂O₃), 13.2 parts of potassium carbonate (K₂O), 9.6 parts of cerium nitrate (CeO₂), 3.2 parts of ammonium molybdate (MoO₃), 2.3 parts of calcium hydroxide (CaO), and 1.8 parts of sodium carboxymethyl cellulose. Stir in a mixer for 2 hours until homogeneous. Add the same amount of water as in Example 1 and mix for 2 hours. Then, extrude and granulate the mixture to obtain particles with a diameter of 3 mm and a length of 6 mm. Place the particles in an oven and dry at 80°C for 4 hours, then at 160°C for 4 hours. Finally, calcine them in a muffle furnace at 650°C for 2 hours and then at 900°C for 2 hours to obtain the finished dehydrogenation catalyst. The composition of the dehydrogenation catalyst is listed in Table 1. The XRD pattern of the dehydrogenation catalyst is shown in [Table 1]. Figure 1 .

[0090] 100 mL of dehydrogenation catalyst was loaded into the reactor and incubated at 60 kPa (absolute pressure) and a mass hourly space velocity (WHSV) of 1.0 h⁻¹ for ethylbenzene. -1 The performance was evaluated under the conditions of reaction temperature 605℃ and water ratio 0.8 (wt). The test results after 100 h of reaction are listed in Table 1. The test results after 1000 h of reaction are listed in Table 2.

[0091] Comparative Example 2

[0092] Weigh out the following amounts: 48.5 parts of iron oxide red (Fe₂O₃), 23.2 parts of iron oxide yellow (Fe₂O₃), 13.2 parts of potassium carbonate (K₂O), 9.6 parts of cerium nitrate (CeO₂), 3.2 parts of ammonium molybdate (MoO₃), 1.8 parts of calcium hydroxide (CaO), 0.2 parts of ytterbium nitrate (Yb₂O₃), 0.3 parts of lutetium nitrate (Lu₂O₃), and 1.8 parts of sodium carboxymethyl cellulose. Stir in a mixer for 2 hours until homogeneous. Then add 24% (by weight of the total raw materials for the dehydrogenation catalyst) of deionized water and mix for 2 hours. Next, extrude and granulate the mixture to obtain particles with a diameter of 3 mm and a length of 6 mm. Place the particles in an oven and dry at 80°C for 4 hours, then at 160°C for 4 hours. Finally, calcine them in a muffle furnace at 650°C for 2 hours and then at 900°C for 2 hours to obtain the finished dehydrogenation catalyst. The composition of the dehydrogenation catalyst is listed in Table 1.

[0093] 100 mL of dehydrogenation catalyst was loaded into the reactor and incubated at 60 kPa (absolute pressure) and a mass hourly space velocity (WHSV) of 1.0 h⁻¹ for ethylbenzene. -1 The performance was evaluated under the conditions of reaction temperature 605℃ and water ratio 0.8 (wt). The test results after 100h of reaction are listed in Table 1.

[0094] Comparative Example 3

[0095] Weigh out the following amounts: 48.5 parts of iron oxide red (Fe₂O₃), 23.2 parts of iron oxide yellow (Fe₂O₃), 13.2 parts of potassium carbonate (K₂O), 9.6 parts of cerium nitrate (CeO₂), 3.2 parts of ammonium molybdate (MoO₃), 2.3 parts of calcium hydroxide (CaO), and 1.8 parts of sodium carboxymethyl cellulose. Stir in a mixer for 2 hours until homogeneous. Then add 24% (by weight) of deionized water (based on the total weight of the dehydrogenation catalyst raw materials) and mix for 2 hours. Next, extrude and granulate the mixture to obtain particles with a diameter of 3 mm and a length of 6 mm. Place these particles in an oven and dry at 80°C for 4 hours, then at 160°C for 4 hours. Finally, calcine them in a muffle furnace at 1000°C for 1.5 hours to obtain the finished dehydrogenation catalyst. The composition of the dehydrogenation catalyst is listed in Table 1.

[0096] 100 mL of dehydrogenation catalyst was loaded into the reactor and incubated at 60 kPa (absolute pressure) and a mass hourly space velocity (WHSV) of 1.0 h⁻¹ for ethylbenzene. -1 The performance was evaluated under the conditions of reaction temperature 605℃ and water ratio 0.8 (wt). The test results after 100h of reaction are listed in Table 1, and the test results after 1000h of reaction are listed in Table 2.

[0097] Comparative Example 4

[0098] Weigh out the following amounts: 48.5 parts of iron oxide red (Fe₂O₃), 23.2 parts of iron oxide yellow (Fe₂O₃), 13.2 parts of potassium carbonate (K₂O), 9.6 parts of cerium nitrate (CeO₂), 3.2 parts of ammonium molybdate (MoO₃), 1.8 parts of calcium hydroxide (CaO), 0.5 parts of neodymium nitrate (Nd₂O₃), and 1.8 parts of sodium carboxymethyl cellulose. Stir in a mixer for 2 hours until homogeneous. Then add 24% (by weight) of deionized water (based on the total weight of the dehydrogenation catalyst raw materials) and mix for 2 hours. Next, extrude and granulate the mixture to obtain particles with a diameter of 3 mm and a length of 6 mm. Place these particles in an oven and dry at 80°C for 4 hours, then at 160°C for 4 hours. Finally, calcine them in a muffle furnace at 1000°C for 1.5 hours to obtain the finished dehydrogenation catalyst. The composition of the dehydrogenation catalyst is listed in Table 1.

[0099] 100 mL of dehydrogenation catalyst was loaded into the reactor and incubated at 60 kPa (absolute pressure) and a mass hourly space velocity (WHSV) of 1.0 h⁻¹ for ethylbenzene. -1 The performance was evaluated under the conditions of reaction temperature 605℃ and water ratio 0.8 (wt). The test results after 100h of reaction are listed in Table 1.

[0100] As shown in Table 1, rare earth element Nd can also inhibit the crystal growth of CeO2. However, in addition to adjusting the crystal structure of CeO2, these additives will inevitably affect the surface properties and electronic structure of the catalyst, thus affecting the catalytic performance. Therefore, the styrene selectivity of the catalyst is significantly reduced.

[0101] Table 1. Catalyst composition, properties, and evaluation results for the examples and comparative examples.

[0102]

[0103]

[0104] Note: * Average CeO2 grain size calculated using the Scherrer equation;

[0105] **Ethylbenzene conversion and styrene selectivity after 100 h of reaction at a water ratio of 0.5;

[0106] ***Comparative Example 4 also contains 0.5 parts by weight of Nd2O3.

[0107] Table 2. Stability evaluation results of dehydrogenation catalysts in the examples and comparative examples.

[0108]

[0109]

[0110] The specific embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combining the various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. An ethylbenzene dehydrogenation catalyst, said catalyst being composed of oxides of Fe2O3, K2O, CeO2, MoO3, CaO and RE, wherein RE is selected from at least one of Dy, Yb and Lu; and the average grain size of CeO2 is less than or equal to 30 nm; The catalyst, based on its total mass, has the following component contents expressed as a mass fraction: (a) 60%–86% Fe2O3; (b) 8%–17% K₂O; (c) 4%–11% CeO2; (d) 0.5%–5% MoO3; (e) 0.2%–4% CaO; (f) 0.1% to 3% of the oxides of RE.

2. The catalyst according to claim 1, characterized in that, In the catalyst, the average grain size of CeO2 is 10–30 nm.

3. The catalyst according to claim 2, characterized in that, In the catalyst, the average grain size of CeO2 is 10–25 nm.

4. The catalyst according to claim 1, characterized in that, RE is selected from at least one of Yb and Lu.

5. The catalyst according to claim 4, characterized in that, RE represents Yb and Lu.

6. The catalyst according to claim 4, characterized in that, RE consists of Yb and Lu, in an oxide ratio of 0.1 to 1.

7. A method for preparing the catalyst according to any one of claims 1 to 6, comprising the following steps: The Fe source, K source, Ce source, Mo source, Ca source, RE source, and optional porogen are mixed evenly, kneaded, and calcined to obtain the catalyst. The calcination conditions are a calcination temperature of 900–1100℃ and a calcination time of 0.5–4 hours.

8. The preparation method according to claim 7, characterized in that, The calcination conditions are a calcination temperature of 950–1050℃ and a calcination time of 1–3 hours.

9. The preparation method according to claim 7, characterized in that, The Fe source was added in the form of Fe2O3 oxide; And / or, the K source is added in the form of a potassium salt; the potassium salt is selected from any one or more of potassium carbonate, potassium nitrate, and potassium bicarbonate; And / or, the Ce source is added in the form of a cerium salt; the cerium salt is any one or more of cerium nitrate, cerium oxalate, and cerium carbonate; And / or, the Mo source is added in the form of a molybdenum salt or oxide, wherein the molybdenum salt is ammonium molybdate; And / or, the Ca source is added in the form of an oxide or hydroxide; And / or, the RE source is added in the form of nitrate or chloride; And / or, the pore-forming agent is any one or more of activated carbon, graphite, sodium hydroxymethyl cellulose, and polystyrene microspheres.

10. The preparation method according to claim 9, characterized in that, The Fe source is iron oxide red and / or iron oxide yellow.

11. The preparation method according to claim 9, characterized in that, The amount of the porogen added is 0.01% to 5% of the catalyst mass.

12. The use of a catalyst according to any one of claims 1 to 6 or a catalyst prepared by any one of claims 7 to 11 in the dehydrogenation of ethylbenzene to styrene.

13. The application according to claim 12, characterized in that, The method of application is as follows: the ethylbenzene-containing raw material is contacted with the catalyst in the presence of water vapor to carry out a dehydrogenation reaction, thereby obtaining a styrene-containing product.

14. The application according to claim 13, characterized in that, The application is suitable for the dehydrogenation of ethylbenzene under low water-to-acetate ratios; the low water-to-acetate ratio is below 1.2; and / or, the temperature of the dehydrogenation reaction is 570–640°C; and / or, the pressure of the dehydrogenation reaction is an absolute pressure of 20–100 kPa; and / or, the mass hourly space velocity of ethylbenzene is 0.2–2.0 h⁻¹. -1 .

15. The application according to claim 14, characterized in that, The low water ratio is 0.7 to 1.2.

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