A catalyst for the dehydrogenation of ethylbenzene to styrene, its preparation method and application

Abstract

This invention discloses a catalyst for the dehydrogenation of ethylbenzene to styrene, its preparation method, and its application. The catalyst comprises Fe₂O₃, K₂O, CeO₂, MoO₃, TiO₂, MnO₂, and Co₃O₄; wherein the exposed crystal facet area of ​​TiO₂(001) accounts for more than 60% of the total exposed crystal facet area of ​​TiO₂. This catalyst, when used in the dehydrogenation of ethylbenzene to styrene reaction, exhibits high catalytic activity and good selectivity.

Description

Technical Field

[0001] This invention relates to a catalyst for the dehydrogenation of ethylbenzene to styrene, its preparation method and application, belonging to the field of dehydrogenation catalysis technology in chemical catalysis. Background Technology

[0002] Styrene is an important basic organic raw material, mainly used in the manufacture of polystyrene resin, unsaturated polyester resin, ion exchange resin, synthetic resin coatings, and insulators. These materials have very important applications in industries such as automobile manufacturing, home appliances, textiles, building materials, light industry, and toys. Currently, the catalytic dehydrogenation of ethylbenzene has been the main technical route for styrene production, accounting for approximately 85% of total styrene production capacity. The most crucial core technology in this method is the development of high-performance catalysts for the dehydrogenation of ethylbenzene to styrene. In current industrial applications, catalysts for the dehydrogenation of ethylbenzene to styrene typically contain potassium-doped Fe-based oxides and promoters. CN103769141B discloses a method for synthesizing such Fe-K-based oxide catalysts.

[0003] In the catalytic dehydrogenation reaction of ethylbenzene, toluene and benzene are the main byproducts. Benzene, a byproduct, can be separated by a distillation unit and recycled back to the ethylbenzene unit, while toluene, with low economic value, can only be sold as a low-priced byproduct. Improving the ethylbenzene conversion rate while reducing the amount of byproducts can improve the utilization rate of the raw material ethylbenzene, reduce equipment material consumption, and increase economic benefits. For styrene plants, catalysts with high catalytic activity and good styrene selectivity are preferred. Currently disclosed catalysts for ethylbenzene dehydrogenation to styrene mainly improve the catalyst's activity, selectivity, and stability under reaction conditions by improving the catalyst's structural stability and modifying its surface properties. CN108097260B discloses a K2Fe... 10 O 16 Based on the K2O-CeO2-WO3-based catalyst, the surface of potassium ferrate oxide is modified by introducing at least one alkali metal oxide from Rb2O and Cs2O to enhance the catalytic activity and stability of the catalyst in the dehydrogenation of ethylbenzene to styrene, achieving high styrene yield and selectivity under low water ratio conditions. CN101829576B discloses a method for preparing a catalyst based on Fe2O3-K2O-Ce2O3-MoO3 by adding multiple metal oxides such as CaO, BaO, CuO, ZnO2, Co2O3, and La2O3 as stabilizing agents. The obtained catalyst exhibits high activity and selectivity, low deactivation rate, and high stability in the ethylbenzene dehydrogenation reaction. However, the current methods do not yield significant benefits, and the catalytic activity and styrene selectivity of the catalysts do not fully meet the requirements of practical applications of ethylbenzene dehydrogenation to styrene catalysts. Summary of the Invention

[0004] To address the problems of low activity, poor stability, and low styrene selectivity in existing ethylbenzene dehydrogenation catalysts for styrene production, this invention proposes a catalyst for ethylbenzene dehydrogenation to styrene production, its preparation method, and its application. This catalyst, when applied to the ethylbenzene dehydrogenation to styrene reaction, exhibits high catalytic activity, good catalyst stability, and high styrene selectivity. Furthermore, the preparation method features a simple process flow.

[0005] The first aspect of this invention provides a catalyst for the dehydrogenation of ethylbenzene to styrene. The catalyst comprises Fe2O3, K2O, CeO2, MoO3, TiO2, MnO2, and Co3O4, wherein the exposed crystal surface area of ​​TiO2 (001) accounts for more than 60% of the total exposed crystal surface area of ​​TiO2.

[0006] According to the present invention, preferably, the exposed crystal surface area of ​​TiO2(001) in the catalyst accounts for more than 67% of the total exposed crystal surface area of ​​TiO2, preferably 67% to 98%, for example, but not limited to 69%, 71%, 73%, 78%, 80%, 83%, 87%, 91%, 94%, 98%, etc.

[0007] According to the present invention, the catalyst, based on the total mass of the catalyst and calculated as a mass fraction, comprises the following components:

[0008] (a) 58%–76% Fe2O3;

[0009] (b) 6%–12% K₂O;

[0010] (c) 5%–10% CeO2;

[0011] (d) 3%–7.5% MoO3;

[0012] (e) 4%–8.5% TiO2;

[0013] (f) 1.8%–5.4% MnO2;

[0014] (g) 0.6% to 1.8% of Co3O4.

[0015] A second aspect of this invention provides a method for preparing a catalyst for the dehydrogenation of ethylbenzene to styrene. The method includes:

[0016] (1) The Ti source, hydrofluoric acid and base M are mixed evenly and then calcined for the first time; the base M includes at least one selected from ammonia water and quaternary ammonium base.

[0017] (2) The calcination product of step (1) is mixed evenly with Fe source, K source, Ce source, Mo source, Mn source and Co source, shaped and calcined a second time to obtain the catalyst.

[0018] According to the present invention, in the method, the reaction apparatus in step (1) is a high-pressure vessel, preferably a high-pressure vessel lined with polytetrafluoroethylene. The pressure in step (1) is autogenous pressure. The mixing in step (1) is mechanical stirring; the stirring time is 20-40 min; furthermore, after the materials in step (1) are mixed evenly, they are heated. The heating temperature is 180-200°C, and the time is 18-26 h. After heating, the mixture is naturally cooled, preferably at a cooling rate of 5-10°C / min. After cooling, the mixture can optionally be centrifuged, optionally washed, optionally dried, and then subjected to a first calcination. Washing can be done with water and / or anhydrous ethanol. The drying conditions are: drying at 80-100°C for 10-12 h.

[0019] According to the present invention, in the method, the conditions for the first calcination in step (1) are as follows: the calcination temperature is 550–800°C, preferably 600–750°C; the calcination time is 3–5 h, preferably 1.5–3.5 h. The heating rate during the calcination process is 1–5°C / min. The calcination atmosphere is an oxygen-containing atmosphere, preferably air. The first calcination product is solid TiO2.

[0020] According to the present invention, in the method, the Ti source in step (1) includes at least one of tetrabutyl titanate, tetraisopropyl titanate, titanium tetrachloride, and titanium sulfate, preferably tetrabutyl titanate and / or tetraisopropyl titanate.

[0021] According to the present invention, in the method, in step (1), the quaternary ammonium base includes at least one selected from tetramethylammonium hydroxide, tetraethylammonium hydroxide, and tetrapropylammonium hydroxide, preferably at least one selected from tetrapropylammonium hydroxide and tetraethylammonium hydroxide.

[0022] According to the present invention, in the method, in step (1), the mass concentration of ammonia water is 22-28%.

[0023] According to the present invention, in the method, in step (1), the mass concentration of the hydrofluoric acid is 38-44%.

[0024] According to the present invention, in the method, in step (1), the mass ratio of hydrofluoric acid, base M, and Ti source is 1:0.17-3.13:12.4-16.5, preferably 1:0.45-2.6:13.05-15.63; wherein the hydrofluoric acid is calculated as HF, the base M as the base itself, and the Ti source as the Ti source itself. When the base M is ammonia, it is calculated as NH3·H2O. When the base M is a quaternary ammonium base, it is calculated as tetramethylammonium hydroxide, tetraethylammonium hydroxide, and / or tetrapropylammonium hydroxide.

[0025] According to the present invention, in step (2) of the method, the molding is kneading molding, preferably extrusion molding. The extrusion molding method produces integral, structured catalyst particles with a diameter of 2-5 mm and a length of 3-10 mm. Moisture can be added or evaporated as needed during the molding process. Preferably, the amount of water added accounts for 15-25% of the total raw material. After kneading molding, drying can be carried out at a temperature of 60-180°C; and / or, the drying time is 8-20 hours.

[0026] According to the present invention, in the method, in step (2), the conditions for the second calcination are: calcination temperature of 600-900℃; calcination time of 3-7h; and heating rate of 10-15℃ / min.

[0027] According to the present invention, in the method, in step (2), the mixing method can be a conventional mechanical stirring method.

[0028] According to the present invention, in the method, in step (2), the Fe source, K source, Ce source, Mo source, Mn source, and Co source are oxides and / or salts. Preferably, the Fe source includes one or more of ferric oxide, ferric chloride, ferric acetate, ferric nitrate, and ferric sulfate; and / or, the K source includes one or more of potassium carbonate, potassium bicarbonate, potassium nitrate, potassium chloride, and potassium sulfate; and / or, the Ce source includes one or more of cerium carbonate, cerium oxalate, cerium nitrate, cerium acetate, cerium chloride, and cerium sulfate; and / or, the Mo source includes one or more of ammonium molybdate and ammonium phosphomolybdate; and / or, the Mn source includes one or more of manganese dioxide, manganese chloride, manganese acetate, manganese nitrate, and manganese sulfate; and / or, the Co source includes one or more of cobalt nitrate, cobalt acetate, cobalt chloride, cobalt sulfate, and cobalt acetylacetonate.

[0029] According to the present invention, in step (2) of the method, the catalyst includes Fe2O3, K2O, CeO2, MoO3, TiO2, MnO2, and Co3O4, wherein the exposed crystal surface area of ​​TiO2(001) accounts for more than 60% of the total exposed crystal surface area of ​​TiO2, preferably 60% to 98%. Preferably, the exposed crystal surface area of ​​TiO2(001) in the catalyst accounts for more than 67% of the total exposed crystal surface area of ​​TiO2, more preferably 67% to 98%, for example, but not limited to 69%, 73%, 78%, 80%, 83%, 87%, 91%, 94%, 98%, etc.

[0030] According to the present invention, in step (2) of the method, the catalyst, based on the total mass of the catalyst and calculated by mass fraction, comprises the following components:

[0031] (a) 58%–76% Fe2O3;

[0032] (b) 6%–12% K₂O;

[0033] (c) 5%–10% CeO2;

[0034] (d) 3%–7.5% MoO3;

[0035] (e) 4%–8.5% TiO2;

[0036] (f) 1.8%–5.4% MnO2;

[0037] (g) 0.6% to 1.8% of Co3O4.

[0038] The third aspect of the present invention provides the application of the above-described ethylbenzene dehydrogenation catalyst or the catalyst prepared by the above-described preparation method in the ethylbenzene dehydrogenation to styrene reaction.

[0039] According to the present invention, the application uses ethylbenzene as a raw material, and styrene is obtained after the raw material is reacted with an ethylbenzene dehydrogenation catalyst.

[0040] According to the present invention, the application conditions are: reaction pressure of 20–100 kPa (absolute pressure); and ethylbenzene mass hourly space velocity of 0.2–2.0 h⁻¹. -1 The reaction temperature is 580–640℃; the water ratio (wt) is 1.0–2.0.

[0041] Compared with the prior art, the advantages of this invention are as follows:

[0042] (1) In the prior art, the effect of the exposed crystal faces of TiO2 on the catalyst performance in the dehydrogenation of ethylbenzene to styrene has not been studied. The inventors have discovered that in the dehydrogenation of ethylbenzene to styrene, the catalytic performance of the catalyst can be directly affected by controlling the exposed crystal faces of TiO2 in the catalyst. In the catalyst of this invention, when the area of ​​exposed (001) crystal faces of TiO2 accounts for more than 60% of the total exposed crystal face area of ​​TiO2, the TiO2 nanosheets with mainly exposed (001) crystal faces cooperate and synergize with the Fe-K-Ce-Mo-Mn-Co based catalyst, which can significantly improve the activity, selectivity, and stability of the catalyst. When the proportion of TiO2 exposed (001) crystal faces exceeds 60%, preferably more than 67%, the migration ability of active species on the catalyst surface will be significantly enhanced, thereby reducing the generation of by-products and carbon deposits, and thus improving the selectivity of the catalyst.

[0043] (2) In the preparation method of the catalyst of the present invention, a TiO2 precursor is first prepared, and then mixed with other metal sources, shaped, and calcined to obtain the catalyst. Simultaneously, in the process of preparing the TiO2 precursor, by controlling the relative amounts of titanium source, hydrofluoric acid, and base M, the surface structure of TiO2 in the catalyst can be well controlled, so that the proportion of exposed crystal faces of TiO2(001) exceeds 60%, preferably more than 67%. The catalyst prepared by this method is beneficial to improving the adsorption of reactants, especially ethylbenzene molecules, on the catalyst, thereby enhancing catalytic activity.

[0044] (3) In the application of the catalyst of the present invention, the catalyst is used in the dehydrogenation of ethylbenzene to styrene reaction, and has the characteristics of high catalytic activity, good selectivity, good stability and simple preparation process. Attached Figure Description

[0045] Figure 1 These are HR-TEM images of the main exposed crystal planes of the catalyst obtained in Example 1 of this invention.

[0046] Figure 2 These are HR-TEM images of the main exposed crystal planes of the catalyst obtained in Comparative Example 1 of this invention.

[0047] Figure 3 The results show the in-situ infrared transient reaction characterization of the catalyst obtained in Example 1 of this invention.

[0048] Figure 4 The results show the in-situ infrared transient reaction characterization of the catalyst obtained in Comparative Example 1 of this invention. Detailed Implementation

[0049] To illustrate the invention more clearly, the following embodiments are provided, but the scope of the invention is not limited to the embodiments.

[0050] In this invention, the catalyst activity is evaluated in an isothermal fixed bed. For the activity evaluation of the catalyst for the dehydrogenation of ethylbenzene to styrene, the process is briefly described as follows:

[0051] Deionized water and ethylbenzene were separately metered into a preheating mixer, preheated and mixed into a gaseous state, and then entered the reactor. The reactor was heated by an electric heating wire to reach the set temperature. The reactor was a stainless steel tube, filled with 100 mL of catalyst. The reactants flowing out of the reactor were condensed in water and their composition was analyzed by gas chromatography.

[0052] Ethylbenzene conversion and styrene selectivity are calculated using the following formulas:

[0053]

[0054]

[0055] In this invention, the HR-TEM test of exposed crystal planes was performed using a FEI Titan Cubed Themis G2 300 transmission electron microscope with double spherical aberration correction. The proportion of TiO2 (001) crystal planes to the total exposed crystal planes of TiO2 was obtained by statistical calculation based on the HR-TEM morphology images and geometric characteristics of the catalyst sample; that is, the proportion of observed TiO2 (001) crystal planes to the total observed exposed crystal planes of TiO2. The total exposed crystal planes of TiO2 are the sum of the exposed crystal planes of TiO2 (001) and TiO2 (101).

[0056] In this invention, in-situ infrared (IIR) characterization was performed using a Thermo Fisher Nicolet IS50 infrared spectrometer. The in-situ reaction cell used was a Harrick scientific infrared cell equipped with a mercury-cadmium-telluride MCT / A detector. The spectral acquisition range was 1500-900 cm⁻¹. -1 The resolution is 4cm. -1 (64 scans). All acquired spectra were measured in Kubelka-Munk units. The catalyst loading in the in-situ cell was 0.8 mL, and the ethylbenzene reaction gas was a mixed gas mixture of 1000 ppm (volume concentration, N2 as carrier gas), with a test flow rate of 20 mL / min. During the test, each catalyst was pretreated at 300 °C for 30 minutes under a high-purity N2 atmosphere, and then background spectra were acquired at 620 °C. The infrared spectra acquired in the transient reaction experiment were all subtracted from the background spectra acquired at the corresponding temperatures. The reaction temperature was maintained at 620 °C, and the reaction gas was introduced to observe the changes in the surface reaction of each catalyst over time (within 30 minutes). The maximum Kubelka-Munk intensity of the ethylbenzene adsorption vibration peak was the maximum value within the 30-minute reaction time. The larger the maximum Kubelka-Munk intensity of the ethylbenzene adsorption vibration peak, the better the adsorption of ethylbenzene molecules by the catalyst, thereby improving the catalytic activity. In this invention, the maximum Kubelka-Munk intensity of the ethylbenzene adsorption vibration peak in the in-situ infrared spectrum of the catalyst is above 0.47.

[0057] The evaluation results of each catalyst in this invention are shown in Tables 1 and 2.

[0058] Example 1

[0059] (1) According to the mass ratio of hydrofluoric acid, alkali M, and Ti source of 1:0.78:13.48, tetrabutyl titanate, 40wt% hydrofluoric acid, and tetrapropylammonium hydroxide were weighed and mixed. The mixture was stirred for 30 min, and then placed in a high-pressure reactor with a polytetrafluoroethylene liner. The mixture was kept at 180℃ for 24 h. After the high-pressure reactor cooled naturally (at a rate of 5℃ / min), the product was centrifuged, washed with deionized water and anhydrous ethanol, and dried at 80℃ for 12 h. Then, it was calcined at 650℃ for 2 h to obtain solid TiO2.

[0060] (2) Weigh out, by weight, the following amounts: 68 parts of ferric oxide (Fe₂O₃), 8.5 parts of potassium carbonate (K₂O), 7.2 parts of cerium nitrate (CeO₂), 5.3 parts of ammonium molybdate (MoO₃), 3.6 parts of manganese nitrate (MnO₂), 1.2 parts of cobalt acetate (Co₃O₄), and 6.2 parts of titanium dioxide solid obtained in step (1). Stir in a mixing container for 2 hours until uniformly mixed, and then add an appropriate amount of water. The amount of water added accounts for 21 wt% of the total raw materials.

[0061] The particles were then extruded and granulated to obtain granules with a diameter of 3 mm and a length of 5 mm. These granules were then dried in an oven at 80°C for 4 hours and then at 150°C for 10 hours. Finally, they were calcined in a muffle furnace at 800°C for 5 hours to obtain a monolithic, structured finished catalyst. The heating rate during the calcination process was 10°C / min.

[0062] The main exposed crystal plane photographs of the catalyst obtained in this example, obtained by HR-TEM testing, are shown below. Figure 1 The in-situ infrared transient reaction characterization results of the catalyst obtained in this example are shown in [reference needed]. Figure 3 In the catalyst, the exposed crystal surface area of ​​TiO2(001) accounts for 93% of the total exposed crystal surface area of ​​TiO2. In in-situ infrared spectroscopy, the maximum Kubelka-Munk intensity of the ethylbenzene adsorption vibration peak is 0.85.

[0063] 100 mL of catalyst was loaded into the reactor and incubated at 70 kPa (absolute pressure) and ethylbenzene liquid hourly space velocity (LHSV) of 1.0 h⁻¹. -1 The performance was evaluated at a reaction temperature of 620℃ and a water ratio of 1.0 (wt). The catalyst composition and the evaluation results after 100 h of reaction are shown in Table 1. The stability evaluation results are shown in Table 2.

[0064] Example 2

[0065] (1) According to the mass ratio of hydrofluoric acid, alkali M, and Ti source of 1:0.95:16.34, tetrabutyl titanate, 40wt% hydrofluoric acid, and tetrapropylammonium hydroxide were weighed and mixed. The mixture was stirred for 30 min, and then placed in a high-pressure reactor with a polytetrafluoroethylene liner. The mixture was kept at 180℃ for 24 h. After the high-pressure reactor cooled naturally (at a natural cooling rate of 5℃ / min), the product was centrifuged, washed with deionized water and anhydrous ethanol, and dried at 80℃ for 12 h. Then, it was calcined at 650℃ for 2 h to obtain solid TiO2.

[0066] (2) Weigh out, by weight, the following amounts: 68 parts of ferric oxide (Fe₂O₃), 8.5 parts of potassium carbonate (K₂O), 7.2 parts of cerium nitrate (CeO₂), 5.3 parts of ammonium molybdate (MoO₃), 3.6 parts of manganese nitrate (MnO₂), 1.2 parts of cobalt acetate (Co₃O₄), and 6.2 parts of titanium dioxide solid obtained in step (1). Stir in a mixing container for 2 hours until uniformly mixed, and then add an appropriate amount of water. The amount of water added accounts for 21 wt% of the total raw materials.

[0067] The particles were then extruded and granulated to obtain granules with a diameter of 3 mm and a length of 5 mm. These granules were then dried in an oven at 80°C for 4 hours and then at 150°C for 10 hours. Finally, they were calcined in a muffle furnace at 800°C for 5 hours to obtain a monolithic, structured finished catalyst. The heating rate during the calcination process was 10°C / min.

[0068] In the catalyst, the exposed crystal surface area of ​​TiO2(001) accounts for 66% of the total exposed crystal surface area of ​​TiO2. In in-situ infrared spectroscopy, the maximum Kubelka-Munk intensity of the ethylbenzene adsorption vibration peak is 0.56.

[0069] 100 mL of catalyst was loaded into the reactor and incubated at 70 kPa (absolute pressure) and ethylbenzene liquid hourly space velocity (LHSV) of 1.0 h⁻¹. -1 The performance was evaluated at a reaction temperature of 620℃ and a water ratio of 1.0 (wt). The catalyst composition and the evaluation results after 100 h of reaction are shown in Table 1.

[0070] Example 3

[0071] (1) According to the mass ratio of hydrofluoric acid, alkali M, and Ti source of 1:2.79:13.48, tetrabutyl titanate, 40wt% hydrofluoric acid, and tetrapropylammonium hydroxide were weighed and mixed. The mixture was stirred for 30 min, and then placed in a high-pressure reactor with a polytetrafluoroethylene liner. The reactor was kept at 180℃ for 24 h. After the high-pressure reactor cooled naturally (at a rate of 5℃ / min), the product was centrifuged, washed with deionized water and anhydrous ethanol, and dried at 80℃ for 12 h. Then, it was calcined at 650℃ for 2 h to obtain solid TiO2.

[0072] (2) Weigh out, by weight, the following amounts: 68 parts of ferric oxide (Fe₂O₃), 8.5 parts of potassium carbonate (K₂O), 7.2 parts of cerium nitrate (CeO₂), 5.3 parts of ammonium molybdate (MoO₃), 3.6 parts of manganese nitrate (MnO₂), 1.2 parts of cobalt acetate (Co₃O₄), and 6.2 parts of titanium dioxide solid obtained in step (1). Stir in a mixing container for 2 hours until uniformly mixed, and then add an appropriate amount of water. The amount of water added accounts for 21 wt% of the total raw materials.

[0073] The particles were then extruded and granulated to obtain granules with a diameter of 3 mm and a length of 5 mm. These granules were then dried in an oven at 80°C for 4 hours and then at 150°C for 10 hours. Finally, they were calcined in a muffle furnace at 800°C for 5 hours to obtain a monolithic, structured finished catalyst. The heating rate during the calcination process was 10°C / min.

[0074] In the catalyst, the exposed crystal surface area of ​​TiO2(001) accounts for 64% of the total exposed crystal surface area of ​​TiO2. In in-situ infrared spectroscopy, the maximum Kubelka-Munk intensity of the ethylbenzene adsorption vibration peak is 0.53.

[0075] 100 mL of catalyst was loaded into the reactor and incubated at 70 kPa (absolute pressure) and ethylbenzene liquid hourly space velocity (LHSV) of 1.0 h⁻¹. -1 The performance was evaluated at a reaction temperature of 620℃ and a water ratio of 1.0 (wt). The catalyst composition and the evaluation results after 100 h of reaction are shown in Table 1. The stability evaluation results are shown in Table 2.

[0076] Example 4

[0077] (1) According to the mass ratio of hydrofluoric acid, alkali M, and Ti source of 1:2.23:13.48, tetrabutyl titanate, 40wt% hydrofluoric acid, and tetrapropylammonium hydroxide were weighed and mixed. The mixture was stirred for 30 min, and then placed in a high-pressure reactor with a polytetrafluoroethylene liner. The mixture was kept at 180℃ for 24 h. After the high-pressure reactor cooled naturally (at a rate of 5℃ / min), the product was centrifuged, washed with deionized water and anhydrous ethanol, and dried at 80℃ for 12 h. Then, it was calcined at 650℃ for 2 h to obtain solid TiO2.

[0078] (2) Weigh out, by weight, the following amounts: 68 parts of ferric oxide (Fe₂O₃), 8.5 parts of potassium carbonate (K₂O), 7.2 parts of cerium nitrate (CeO₂), 5.3 parts of ammonium molybdate (MoO₃), 3.6 parts of manganese nitrate (MnO₂), 1.2 parts of cobalt acetate (Co₃O₄), and 6.2 parts of titanium dioxide solid obtained in step (1). Stir in a mixing container for 2 hours until uniformly mixed, and then add an appropriate amount of water. The amount of water added accounts for 21 wt% of the total raw materials.

[0079] The particles were then extruded and granulated to obtain granules with a diameter of 3 mm and a length of 5 mm. These granules were then dried in an oven at 80°C for 4 hours and then at 150°C for 10 hours. Finally, they were calcined in a muffle furnace at 800°C for 5 hours to obtain a monolithic, structured finished catalyst. The heating rate during the calcination process was 10°C / min.

[0080] In the catalyst, the exposed crystal surface area of ​​TiO2(001) accounts for 88% of the total exposed crystal surface area of ​​TiO2. In in-situ infrared spectroscopy, the maximum Kubelka-Munk intensity of the ethylbenzene adsorption vibration peak is 0.78.

[0081] 100 mL of catalyst was loaded into the reactor and incubated at 70 kPa (absolute pressure) and ethylbenzene liquid hourly space velocity (LHSV) of 1.0 h⁻¹. -1 The performance was evaluated at a reaction temperature of 620℃ and a water ratio of 1.0 (wt). The catalyst composition and the evaluation results after 100 h of reaction are shown in Table 1.

[0082] Example 5

[0083] (1) According to the mass ratio of hydrofluoric acid, alkali M, and Ti source of 1:0.78:15.36, tetrabutyl titanate, 40wt% hydrofluoric acid, and tetrapropylammonium hydroxide were weighed and mixed. The mixture was stirred for 30 min, and then placed in a high-pressure reactor with a polytetrafluoroethylene liner. The reactor was kept at 180℃ for 24 h. After the high-pressure reactor cooled naturally (at a rate of 5℃ / min), the product was centrifuged, washed with deionized water and anhydrous ethanol, and dried at 80℃ for 12 h. Then, it was calcined at 650℃ for 2 h to obtain solid TiO2.

[0084] (2) Weigh out, by weight, the following amounts: 68 parts of ferric oxide (Fe₂O₃), 8.5 parts of potassium carbonate (K₂O), 7.2 parts of cerium nitrate (CeO₂), 5.3 parts of ammonium molybdate (MoO₃), 3.6 parts of manganese nitrate (MnO₂), 1.2 parts of cobalt acetate (Co₃O₄), and 6.2 parts of titanium dioxide solid obtained in step (1). Stir in a mixing container for 2 hours until uniformly mixed, and then add an appropriate amount of water. The amount of water added accounts for 21 wt% of the total raw materials.

[0085] The particles were then extruded and granulated to obtain granules with a diameter of 3 mm and a length of 5 mm. These granules were then dried in an oven at 80°C for 4 hours and then at 150°C for 10 hours. Finally, they were calcined in a muffle furnace at 800°C for 5 hours to obtain a monolithic, structured finished catalyst. The heating rate during the calcination process was 10°C / min.

[0086] In the catalyst, the exposed crystal surface area of ​​TiO2(001) accounts for 82% of the total exposed crystal surface area of ​​TiO2. In in-situ infrared spectroscopy, the maximum Kubelka-Munk intensity of the ethylbenzene adsorption vibration peak is 0.71.

[0087] 100 mL of catalyst was loaded into the reactor and incubated at 70 kPa (absolute pressure) and ethylbenzene liquid hourly space velocity (LHSV) of 1.0 h⁻¹. -1 The performance was evaluated at a reaction temperature of 620℃ and a water ratio of 1.0 (wt). The catalyst composition and the evaluation results after 100 h of reaction are shown in Table 1.

[0088] Example 6

[0089] (1) According to the mass ratio of hydrofluoric acid, alkali M, and Ti source of 1:1.67:14.55, tetrabutyl titanate, 40wt% hydrofluoric acid, and tetrapropylammonium hydroxide were weighed and mixed. The mixture was stirred for 30 min, and then placed in a high-pressure reactor with a polytetrafluoroethylene liner. The mixture was kept at 180℃ for 24 h. After the high-pressure reactor cooled naturally (at a rate of 5℃ / min), the product was centrifuged, washed with deionized water and anhydrous ethanol, and dried at 80℃ for 12 h. Then, it was calcined at 650℃ for 2 h to obtain solid TiO2.

[0090] (2) Weigh out, by weight, the following amounts: 68 parts of ferric oxide (Fe₂O₃), 8.5 parts of potassium carbonate (K₂O), 7.2 parts of cerium nitrate (CeO₂), 5.3 parts of ammonium molybdate (MoO₃), 3.6 parts of manganese nitrate (MnO₂), 1.2 parts of cobalt acetate (Co₃O₄), and 6.2 parts of titanium dioxide solid obtained in step (1). Stir in a mixing container for 2 hours until uniformly mixed, and then add an appropriate amount of water. The amount of water added accounts for 21 wt% of the total raw materials.

[0091] The particles were then extruded and granulated to obtain granules with a diameter of 3 mm and a length of 5 mm. These granules were then dried in an oven at 80°C for 4 hours and then at 150°C for 10 hours. Finally, they were calcined in a muffle furnace at 800°C for 5 hours to obtain a monolithic, structured finished catalyst. The heating rate during the calcination process was 10°C / min.

[0092] In the catalyst, the exposed crystal surface area of ​​TiO2(001) accounts for 85% of the total exposed crystal surface area of ​​TiO2. In in-situ infrared spectroscopy, the maximum Kubelka-Munk intensity of the ethylbenzene adsorption vibration peak is 0.75.

[0093] 100 mL of catalyst was loaded into the reactor and incubated at 70 kPa (absolute pressure) and ethylbenzene liquid hourly space velocity (LHSV) of 1.0 h⁻¹. -1 The performance was evaluated at a reaction temperature of 620℃ and a water ratio of 1.0 (wt). The catalyst composition and the evaluation results after 100 h of reaction are shown in Table 1.

[0094] Example 7

[0095] (1) According to the mass ratio of hydrofluoric acid, alkali M, and Ti source of 1:0.78:13.48, tetrabutyl titanate, 40wt% hydrofluoric acid, and tetrapropylammonium hydroxide were weighed and mixed. The mixture was stirred for 30 min, and then placed in a high-pressure reactor with a polytetrafluoroethylene liner. The mixture was kept at 180℃ for 24 h. After the high-pressure reactor cooled naturally (at a rate of 5℃ / min), the product was centrifuged, washed with deionized water and anhydrous ethanol, and dried at 80℃ for 12 h. Then, it was calcined at 650℃ for 2 h to obtain solid TiO2.

[0096] (2) Weigh out, by weight, the following amounts: 68 parts of ferric oxide (Fe₂O₃), 8.5 parts of potassium carbonate (K₂O), 7.2 parts of cerium nitrate (CeO₂), 5.8 parts of ammonium molybdate (MoO₃), 4.6 parts of manganese nitrate (MnO₂), 1.7 parts of cobalt acetate (Co₃O₄), and 4.2 parts of titanium dioxide solid obtained in step (1). Stir in a mixing container for 2 hours until uniformly mixed, and then add an appropriate amount of water. The amount of water added accounts for 21 wt% of the total raw materials.

[0097] The particles were then extruded and granulated to obtain granules with a diameter of 3 mm and a length of 5 mm. These granules were then dried in an oven at 80°C for 4 hours and then at 150°C for 10 hours. Finally, they were calcined in a muffle furnace at 800°C for 5 hours to obtain a monolithic, structured finished catalyst. The heating rate during the calcination process was 10°C / min.

[0098] In the catalyst, the exposed crystal surface area of ​​TiO2(001) accounts for 77% of the total exposed crystal surface area of ​​TiO2. In in-situ infrared spectroscopy, the maximum Kubelka-Munk intensity of the ethylbenzene adsorption vibration peak is 0.68.

[0099] 100 mL of catalyst was loaded into the reactor and incubated at 70 kPa (absolute pressure) and ethylbenzene liquid hourly space velocity (LHSV) of 1.0 h⁻¹. -1The performance was evaluated at a reaction temperature of 620℃ and a water ratio of 1.0 (wt). The catalyst composition and the evaluation results after 100 h of reaction are shown in Table 1.

[0100] Example 8

[0101] (1) According to the mass ratio of hydrofluoric acid, alkali M, and Ti source of 1:0.78:13.48, tetrabutyl titanate, 40wt% hydrofluoric acid, and tetrapropylammonium hydroxide were weighed and mixed. The mixture was stirred for 30 min, and then placed in a high-pressure reactor with a polytetrafluoroethylene liner. The mixture was kept at 180℃ for 24 h. After the high-pressure reactor cooled naturally (at a rate of 5℃ / min), the product was centrifuged, washed with deionized water and anhydrous ethanol, and dried at 80℃ for 12 h. Then, it was calcined at 650℃ for 2 h to obtain solid TiO2.

[0102] (2) Weigh out, by weight, the following amounts: 68 parts of ferric oxide (Fe₂O₃), 8.5 parts of potassium carbonate (K₂O), 6.2 parts of cerium nitrate (CeO₂), 4.8 parts of ammonium molybdate (MoO₃), 3.1 parts of manganese nitrate (MnO₂), 1.2 parts of cobalt acetate (Co₃O₄), and 8.2 parts of titanium dioxide solid obtained in step (1). Stir in a mixing container for 2 hours until homogeneous and add an appropriate amount of water. The amount of water added accounts for 21 wt% of the total raw materials.

[0103] The particles were then extruded and granulated to obtain granules with a diameter of 3 mm and a length of 5 mm. These granules were then dried in an oven at 80°C for 4 hours and then at 150°C for 10 hours. Finally, they were calcined in a muffle furnace at 800°C for 5 hours to obtain a monolithic, structured finished catalyst. The heating rate during the calcination process was 10°C / min.

[0104] In the catalyst, the exposed crystal surface area of ​​TiO2(001) accounts for 74% of the total exposed crystal surface area of ​​TiO2.

[0105] In in-situ infrared spectroscopy, the maximum Kubelka-Munk intensity of the ethylbenzene adsorption vibration peak was 0.64.

[0106] 100 mL of catalyst was loaded into the reactor and incubated at 70 kPa (absolute pressure) and ethylbenzene liquid hourly space velocity (LHSV) of 1.0 h⁻¹. -1 The performance was evaluated at a reaction temperature of 620℃ and a water ratio of 1.0 (wt). The catalyst composition and the evaluation results after 100 h of reaction are shown in Table 1. The stability evaluation results are shown in Table 2.

[0107] Example 9

[0108] Same as Example 1, except for the different catalyst composition. The feed amount for step (2) is shown in Table 1. The test results are shown in Table 1.

[0109] In the catalyst, the exposed crystal surface area of ​​TiO2(001) accounts for 93% of the total exposed crystal surface area of ​​TiO2.

[0110] In in-situ infrared spectroscopy, the maximum Kubelka-Munk intensity of the ethylbenzene adsorption vibration peak was 0.78.

[0111] Example 10

[0112] Same as Example 1, except that the alkali M is ammonia. In step (1), tetrabutyl titanate, 40wt% hydrofluoric acid and 25wt% ammonia are weighed and mixed according to the mass ratio of hydrofluoric acid, alkali M and Ti source of 1:0.78:13.48.

[0113] In the catalyst, the exposed crystal surface area of ​​TiO2(001) accounts for 89% of the total exposed crystal surface area of ​​TiO2.

[0114] In in-situ infrared spectroscopy, the maximum Kubelka-Munk intensity of the ethylbenzene adsorption vibration peak was 0.80.

[0115] Comparative Example 1

[0116] (1) According to the mass ratio of hydrofluoric acid, base M, and Ti source of 1:3.35:16.82, tetrabutyl titanate, 40wt% hydrofluoric acid, and tetrapropylammonium hydroxide were weighed and mixed. The mixture was stirred for 30 min, and then placed in a high-pressure reactor with a polytetrafluoroethylene liner. The mixture was kept at 180℃ for 24 h. After the high-pressure reactor cooled naturally (at a rate of 5℃ / min), the product was centrifuged, washed with deionized water and anhydrous ethanol, and dried at 80℃ for 12 h. Then, it was calcined at 650℃ for 2 h to obtain solid TiO2.

[0117] (2) Weigh out, by weight, the following amounts: 68 parts of ferric oxide (Fe₂O₃), 8.5 parts of potassium carbonate (K₂O), 7.2 parts of cerium nitrate (CeO₂), 5.3 parts of ammonium molybdate (MoO₃), 3.6 parts of manganese nitrate (MnO₂), 1.2 parts of cobalt acetate (Co₃O₄), and 6.2 parts of titanium dioxide solid obtained in step (1). Stir in a mixing container for 2 hours until uniformly mixed, and then add an appropriate amount of water. The amount of water added accounts for 21 wt% of the total raw materials.

[0118] The particles were then extruded and granulated to obtain granules with a diameter of 3 mm and a length of 5 mm. These granules were then dried in an oven at 80°C for 4 hours and then at 150°C for 10 hours. Finally, they were calcined in a muffle furnace at 800°C for 5 hours to obtain a monolithic, structured finished catalyst. The heating rate during the calcination process was 10°C / min.

[0119] The main exposed crystal plane photographs of the catalyst obtained in this example, obtained by HR-TEM testing, are shown below. Figure 2 The in-situ infrared transient reaction characterization results of the catalyst obtained in this example are shown in [reference needed]. Figure 4 In the catalyst, the exposed crystal surface area of ​​TiO2(001) accounts for 52% of the total exposed crystal surface area of ​​TiO2.

[0120] In in-situ infrared spectroscopy, the maximum Kubelka-Munk intensity of the ethylbenzene adsorption vibration peak was 0.41.

[0121] 100 mL of catalyst was loaded into the reactor and incubated at 70 kPa (absolute pressure) and ethylbenzene liquid hourly space velocity (LHSV) of 1.0 h⁻¹. -1 The performance was evaluated at a reaction temperature of 620℃ and a water ratio of 1.0 (wt). The catalyst composition and the evaluation results after 100 h of reaction are shown in Table 1. The stability evaluation results are shown in Table 2.

[0122] Comparative Example 2

[0123] (1) According to the mass ratio of hydrofluoric acid, alkali M, and Ti source of 1:1.78:17.25, tetrabutyl titanate, 40wt% hydrofluoric acid, and tetrapropylammonium hydroxide were weighed and mixed. The mixture was stirred for 30 min, and then placed in a high-pressure reactor with a polytetrafluoroethylene liner. The mixture was kept at 180℃ for 24 h. After the high-pressure reactor cooled naturally (at a natural cooling rate of 5℃ / min), the product was centrifuged, washed with deionized water and anhydrous ethanol, and dried at 80℃ for 12 h. Then, it was calcined at 650℃ for 2 h to obtain solid TiO2.

[0124] (2) Weigh out, by weight, the following amounts: 68 parts of ferric oxide (Fe₂O₃), 8.5 parts of potassium carbonate (K₂O), 7.2 parts of cerium nitrate (CeO₂), 5.3 parts of ammonium molybdate (MoO₃), 3.6 parts of manganese nitrate (MnO₂), 1.2 parts of cobalt acetate (Co₃O₄), and 6.2 parts of titanium dioxide solid obtained in step (1). Stir in a mixing container for 2 hours until uniformly mixed, and then add an appropriate amount of water. The amount of water added accounts for 21 wt% of the total raw materials.

[0125] The particles were then extruded and granulated to obtain granules with a diameter of 3 mm and a length of 5 mm. These granules were then dried in an oven at 80°C for 4 hours and then at 150°C for 10 hours. Finally, they were calcined in a muffle furnace at 800°C for 5 hours to obtain a monolithic, structured finished catalyst. The heating rate during the calcination process was 10°C / min.

[0126] In the catalyst, the exposed crystal surface area of ​​TiO2(001) accounts for 56% of the total exposed crystal surface area of ​​TiO2. In in-situ infrared spectroscopy, the maximum Kubelka-Munk intensity of the ethylbenzene adsorption vibration peak is 0.44.

[0127] 100 mL of catalyst was loaded into the reactor and incubated at 70 kPa (absolute pressure) and ethylbenzene liquid hourly space velocity (LHSV) of 1.0 h⁻¹. -1 The performance was evaluated at a reaction temperature of 620℃ and a water ratio of 1.0 (wt). The catalyst composition and the evaluation results after 100 h of reaction are shown in Table 1. The stability evaluation results are shown in Table 2.

[0128] Comparative Example 3

[0129] (1) Weigh 25 mL of tetrabutyl titanate and place it in a high-pressure reactor with a polytetrafluoroethylene liner. Keep it at 180 °C for 24 h. After the high-pressure reactor cools naturally (at a rate of 5 °C / min), the product is centrifuged, washed with deionized water and anhydrous ethanol, and dried at 80 °C for 12 h. Then, it is calcined at 650 °C for 2 h to obtain solid TiO2.

[0130] (2) Weigh out, by weight, the following amounts: 68 parts of ferric oxide (Fe₂O₃), 8.5 parts of potassium carbonate (K₂O), 7.2 parts of cerium nitrate (CeO₂), 5.3 parts of ammonium molybdate (MoO₃), 3.6 parts of manganese nitrate (MnO₂), 1.2 parts of cobalt acetate (Co₃O₄), and 6.2 parts of titanium dioxide solid obtained in step (1). Stir in a mixing container for 2 hours until uniformly mixed, and then add an appropriate amount of water. The amount of water added accounts for 21 wt% of the total raw materials.

[0131] The particles were then extruded and granulated to obtain granules with a diameter of 3 mm and a length of 5 mm. These granules were then dried in an oven at 80°C for 4 hours and then at 150°C for 10 hours. Finally, they were calcined in a muffle furnace at 800°C for 5 hours to obtain a monolithic, structured finished catalyst. The heating rate during the calcination process was 10°C / min.

[0132] In the catalyst, the exposed crystal surface area of ​​TiO2(001) accounts for 39% of the total exposed crystal surface area of ​​TiO2. In in-situ infrared spectroscopy, the maximum Kubelka-Munk intensity of the ethylbenzene adsorption vibration peak is 0.30.

[0133] 100 mL of catalyst was loaded into the reactor and incubated at 70 kPa (absolute pressure) and ethylbenzene liquid hourly space velocity (LHSV) of 1.0 h⁻¹. -1 The performance was evaluated at a reaction temperature of 620℃ and a water ratio of 1.0 (wt). The catalyst composition and the evaluation results after 100 h of reaction are shown in Table 1. The stability evaluation results are shown in Table 2.

[0134] Table 1. Styrene catalyst composition and evaluation results after 100 h of reaction for the examples and comparative examples.

[0135]

[0136]

[0137] Table 2. Stability evaluation results of styrene catalysts in the examples and comparative examples.

[0138]

[0139] 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. A catalyst for dehydrogenation of ethylbenzene to styrene comprising Fe2O3, K2O, CeO2, M0O3, TiO2, MnO2, Co3O4, wherein, The exposed crystal plane area of ​​TiO2(001) accounts for more than 60% of the total exposed crystal plane area of ​​TiO2, and the total exposed crystal plane of TiO2 is the sum of the exposed crystal planes of TiO2(001) and TiO2(101); The preparation method of the catalyst for the dehydrogenation of ethylbenzene to styrene includes: (1) The Ti source, hydrofluoric acid, and base M are mixed evenly and then calcined for the first time; the base M includes at least one selected from ammonia water and quaternary ammonium bases; (2) The calcination product of step (1) is mixed evenly with Fe source, K source, Ce source, Mo source, Mn source and Co source, shaped and calcined a second time to obtain the catalyst; The catalyst, based on its total mass and calculated as a mass fraction, comprises the following components: (a) 58%~76% Fe2O3; (b) 6%~12% K2O; (c) 5%~10% CeO2; (d) 3%~7.5% MoO3; (e) 4%~8.5% TiO2; (f) 1.8%~5.4% MnO2; (g) 0.6%~1.8% Co3O4.

2. A method for preparing the catalyst according to claim 1, comprising: (1) The Ti source, hydrofluoric acid, and base M are mixed evenly and then calcined for the first time; the base M includes at least one selected from ammonia water and quaternary ammonium bases; (2) The calcination product of step (1) is mixed evenly with Fe source, K source, Ce source, Mo source, Mn source and Co source, shaped and calcined a second time to obtain the catalyst.

3. The preparation method according to claim 2, characterized in that, In step (1), the quaternary ammonium base includes at least one of tetramethylammonium hydroxide, tetraethylammonium hydroxide, and tetrapropylammonium hydroxide; And / or, the Ti source in step (1) includes at least one of tetrabutyl titanate, tetraisopropyl titanate, titanium tetrachloride, and titanium sulfate.

4. The preparation method according to claim 3, characterized in that, In step (1), the quaternary ammonium base includes at least one of tetrapropylammonium hydroxide and tetraethylammonium hydroxide; And / or, the Ti source in step (1) includes at least one of tetrabutyl titanate and tetraisopropyl titanate.

5. The preparation method according to claim 2, characterized in that, In step (1), the mass ratio of hydrofluoric acid, base M, and Ti source is 1:0.17~3.13:12.4~16.

5.

6. The preparation method according to claim 2, characterized in that, In step (1), the mass ratio of hydrofluoric acid, base M, and Ti source is 1:0.45~2.6:13.05~15.

63.

7. The preparation method according to claim 2, characterized in that, The conditions for the first roasting in step (1) are: roasting temperature of 550~800°C; and / or roasting time of 3~5h.

8. The preparation method according to claim 7, characterized in that, The conditions for the first calcination in step (1) are: calcination temperature of 600~750 °C; and / or calcination time of 1.5~3.5 h.

9. The preparation method according to claim 2, characterized in that, In step (2), the conditions for the second calcination are: calcination temperature of 600~900 ℃; calcination time of 3~7 h; and heating rate of 10~15 ℃ / min.

10. The preparation method according to claim 2, characterized in that, In step (2), the Fe source, K source, Ce source, Mo source, Mn source, and Co source are oxides and / or salts.

11. The preparation method according to claim 10, characterized in that, In step (2), the Fe source includes one or more of ferric oxide, ferric chloride, ferric acetate, ferric nitrate, and ferric sulfate; And / or, the K source includes one or more of potassium carbonate, potassium bicarbonate, potassium nitrate, potassium chloride, and potassium sulfate; And / or, the Ce source includes one or more of cerium carbonate, cerium oxalate, cerium nitrate, cerium acetate, cerium chloride, and cerium sulfate; And / or, the Mo source includes one or more of ammonium molybdate and ammonium phosphomolybdate; And / or, the Mn source includes one or more of manganese dioxide, manganese chloride, manganese acetate, manganese nitrate, and manganese sulfate; And / or, the Co source includes one or more of cobalt nitrate, cobalt acetate, cobalt chloride, cobalt sulfate, and cobalt acetylacetonate.

12. The use of the catalyst according to claim 1 or the catalyst prepared by any one of claims 2 to 11 in the dehydrogenation of ethylbenzene to styrene reaction.

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