Iron catalyst with high dispersion and high carbon deposition resistance, preparation method and application of iron catalyst in preparation of styrene from ethylbenzene

Abstract

The invention discloses a high-dispersion and high-carbon-deposition-resistance iron catalyst, a preparation method and application of the iron catalyst in preparation of styrene from ethylbenzene, and belongs to the technical field of catalysts. The catalyst takes an aluminum oxide gel network as a framework, and iron, potassium and cerium are embedded in the framework in situ. A sol-gel method is adopted for preparation, an additional binder is not needed, the active component is highly dispersed, and the mechanical strength is high. The catalyst can be directly used for preparing styrene through ethylbenzene dehydrogenation under the condition of no water vapor and shows excellent carbon deposition resistance and operation stability, carbon deposits are easily eliminated through air roasting, and potassium loss can be neglected. Compared with a traditional iron-based catalyst, the catalyst greatly reduces the water-hydrocarbon ratio and energy consumption, has the remarkable advantages of energy conservation and consumption reduction, and is suitable for green upgrading and reconstruction of an industrial ethylbenzene dehydrogenation device.

Description

Technical Field

[0001] This invention belongs to the field of catalyst technology, specifically relating to a highly dispersed and highly resistant-to-coking iron catalyst, its preparation method, and its application in the production of styrene from ethylbenzene. Background Technology

[0002] The catalytic dehydrogenation of ethylbenzene to styrene is an important industrial reaction. Currently, the most widely used industrial catalyst is potassium-promoted iron oxide, which carries out the dehydrogenation reaction under high temperature, low pressure, and with a large amount of superheated steam. Besides serving as a heat source and a diluent to reduce the partial pressure of ethylbenzene, steam plays a crucial role in removing coke deposits from the catalyst surface. Because the coking rate on iron oxide catalysts is currently fast, a large amount of steam is required, leading to high energy consumption, large product condensation, and high equipment costs, resulting in persistently high production costs. Therefore, reducing steam consumption, i.e., lowering the water-to-hydrocarbon ratio, is one of the core directions for energy conservation and cost reduction in styrene plants. Improving the catalyst's resistance to coking or slowing down the coking rate will effectively reduce the consumption of steam or other gases required for coking removal during the reaction, thereby fundamentally achieving energy conservation and cost reduction. This has become a key research focus.

[0003] A review of the published patents reveals that current research on ethylbenzene dehydrogenation catalysts primarily focuses on optimizing additives. For example, the Shanghai Petrochemical Research Institute of China Petroleum & Chemical Corporation (Sinopec) has experimented with adding rare earth metal oxides such as Eu2O3, Tb2O3, and Ho2O3 (CN106582681A), or adding cerium oxide with (111) as the main crystal facet (CN115957775A). Suzhou Tuorui Technology Co., Ltd. has conducted research on adding more alkali metal oxide Na2O (CN106927997A). China National Petroleum Corporation (CNPC) has modified the catalyst surface with alkali metal oxides Rb2O and Cs2O in the form of nitrate solutions via impregnation or spraying (CN105749934A). The common feature of these patents is that they use iron oxides as the main component, and through the optimization of additives, the water-to-hydrogen ratio has been reduced to a certain extent.

[0004] Researchers noted that even with reduced water vapor usage, potassium loss remained a problem, leading to decreased catalyst activity and accelerated coking rate. To address this, the Shanghai Research Institute of Petrochemical Technology introduced potassium silicate species into the catalyst to reduce potassium loss and improve its anti-coking ability (CN109569637A). Furthermore, Sinopec disclosed a catalyst with good anti-coking ability under low water-to-hydrogen ratio conditions (CN1981930A), which does not add silicate cement during catalyst preparation because it contains weakly acidic SiO2, which would promote coking reaction. Suzhou Tuorui Technology Co., Ltd. prepared a binder-free, low water-to-hydrogen ratio ethylbenzene dehydrogenation catalyst (US10406508B2), maintaining high anti-coking stability under low water-to-hydrogen ratio conditions. These patents share the common feature of reducing coking precursor formation by regulating surface acidity (reducing acid content or eliminating acidic sites) and maintaining overall catalyst anti-coking performance by stabilizing potassium species to inhibit potassium loss.

[0005] Currently, researchers are using pore structure regulation and support design to achieve uniform distribution of active components, thereby improving the utilization rate of active sites and suppressing coking caused by agglomeration, thus enhancing the overall stability of the catalyst. Taiyuan University of Technology used ZSM-5 / MCM-48 microporous / mesoporous composite molecular sieves as a support, utilizing mesoporous channels to achieve high dispersion of active components and slow down coking (CN103537317A). The Institute of Metal Research, Chinese Academy of Sciences, developed a highly dispersed palladium-based catalyst supported on hollow nitrogen-doped carbon nanospheres. Nitrogen doping provides anchoring sites, achieving high dispersion of active components (CN113578359A), avoiding over-activation of ethylbenzene by local active sites, which leads to deep cracking and coking reactions. These studies demonstrate that achieving high dispersion of active components can effectively suppress coking, providing important inspiration for the high-dispersion design of iron-based catalysts.

[0006] In summary, significant progress has been made in potassium-promoted iron oxide catalysts in reducing the water-to-hydrogen ratio and improving resistance to coking. However, to further meet the demands of industrial energy conservation and emission reduction, the development of more energy-efficient and highly coking-resistant ethylbenzene dehydrogenation catalysts still holds immense application potential. Summary of the Invention

[0007] The technical problem to be solved by this invention is to provide an iron-based catalyst with highly dispersed active components, high resistance to coking, and suitable for anhydrous conditions, as well as its preparation method and application in the direct dehydrogenation of ethylbenzene, which are caused by severe catalyst coking in the current ethylbenzene dehydrogenation production.

[0008] To address the aforementioned technical problems, this invention first designed and prepared a novel, highly dispersed, and high-strength iron catalyst, altering the existing forms of iron and its additives. Employing a sol-gel method, using an alumina gel network as the structural framework, iron and additive precursors are simultaneously added during sol formation, allowing them to embed in situ into the network structure, achieving high dispersion of iron and additives. This not only improves the utilization rate of active sites and facilitates synergistic effects between active components, but also inhibits the migration and aggregation of active components. Thus, while enhancing catalytic activity, it also strengthens resistance to coking and structural stability, fundamentally solving the problems of high water-to-hydrocarbon ratios, potassium loss, and high energy consumption caused by severe coking in existing technologies.

[0009] The ethylbenzene dehydrogenation catalyst of this invention contains aluminum, iron, potassium, cerium, and oxygen. It is a high-strength gel catalyst with alumina as the main framework and highly dispersed iron, potassium, cerium, and other species inside. The content of each element, calculated as oxides with a mass percentage of 100%, is as follows:

[0010] 64%~88% aluminum, calculated as Al2O3;

[0011] 5%~15% iron, calculated as Fe2O3;

[0012] Potassium content of 5% to 15%, calculated as K2O;

[0013] 2% to 6% cerium, calculated as CeO2.

[0014] The preparation method of the highly dispersed and highly coking-resistant iron catalyst of the present invention adopts a sol-gel method, which is different from the traditional dry mixing and kneading method. The steps are as follows:

[0015] 1) Prepare mixed solvent A by mixing anhydrous ethanol and deionized water;

[0016] 2) Dissolve aluminum salt, iron salt, potassium salt and cerium salt in the mixed solvent A obtained in step 1), stir and heat to obtain mixed salt solution B;

[0017] 3) Cool the mixed salt solution B obtained in step 2) to room temperature, and slowly add epoxy gelation accelerator dropwise at a constant rate under certain temperature and with thorough stirring to form a semi-gel.

[0018] 4) Transfer the semigel obtained in step 3) to a constant temperature bath and further promote gel formation at a certain temperature to obtain wet gel precursor C;

[0019] 5) Seal the wet gel precursor C obtained in step 4) with ethanol and age it at room temperature for a certain period of time.

[0020] 6) After the wet gel precursor C from step 5) is aged, it is dried and calcined to obtain the highly dispersed and highly resistant to carbon deposition iron catalyst.

[0021] In step 1), the volume ratio of anhydrous ethanol to deionized water is 1 to 4:1, preferably 2:1;

[0022] In step 2), the aluminum salt, iron salt, potassium salt, and cerium salt are one or two of chloride and acetate, preferably chloride; to maintain the mechanical strength of the gel, the molar concentration of aluminum ions in the mixed salt solution B is 0.6~1.5 mol / L (preferably 0.8~1.2 mol / L), the molar concentration of iron ions is 0.05~0.15 mol / L, the molar concentration of potassium ions is 0.1~0.2 mol / L, and the molar concentration of cerium ions is 0.02~0.04 mol / L; the heating temperature is 40~90℃, preferably 60~80℃; the heating time is 15~60 min; and the stirring speed is 200~500 r / min.

[0023] In step 3), 15-20 mL of epoxy gelation accelerator is added dropwise to 30 mL of mixed salt solution B; the temperature range for adding the epoxy gelation accelerator is 0-10℃, preferably 0-5℃; the epoxy gelation accelerator is one of propylene oxide, epichlorohydrin, and 1,2-epoxybutane; the dropping rate is 3-5 mL / min.

[0024] In step 4), the temperature for further promoting gel formation is 50~80℃, preferably 60~70℃; the time for promoting gel formation is 3~10 min.

[0025] In step 5), the aging time is 12h~72h, preferably 24~48h;

[0026] In step 6), the drying temperature is 30~80℃, preferably 40~60℃; the calcination temperature is 600~900℃, preferably 700~800℃; the calcination atmosphere is pure oxygen or air; and the calcination time is 1~8h, preferably 4~6h.

[0027] The highly dispersed and highly resistant to coking iron catalyst of the present invention is prepared by the above method.

[0028] The highly dispersed and anti-coking iron catalyst described in this invention can be applied in the direct dehydrogenation of ethylbenzene, with a reaction pressure of negative pressure or atmospheric pressure (1 standard atmosphere is atmospheric pressure), a reaction temperature of 550~610℃, and an ethylbenzene space velocity of 0.1~10h. -1 .

[0029] Features and advantages of this invention:

[0030] (1) The catalyst of the present invention uses an alumina gel network as its structural framework, with iron, potassium, and cerium embedded in the network in situ. Characterization results (XRD / TEM, etc.) show that the active components are highly dispersed and the utilization rate of active sites is high. Therefore, excellent catalytic performance can be obtained with a low amount of metal, and the cost is low.

[0031] (2) The catalyst described in this invention does not require the addition of a binder during the preparation process. It can obtain high mechanical strength through a sol-gel process alone, thus avoiding the influence of acidic sites introduced by the binder on the coking rate.

[0032] (3) The catalyst described in this invention exhibits strong resistance to coking and a low coking rate under direct dehydrogenation of ethylbenzene without anhydrous vapor, and can operate stably for a long time. The deactivated catalyst can be regenerated by calcination at the reaction temperature or lower in an air atmosphere. Potassium loss is negligible, the operating cost is low, and it has significant energy-saving and consumption-reducing advantages. Attached Figure Description

[0033] Figure 1 The results are for the performance of Example 1 during multiple cycles of air regeneration-ethylbenzene dehydrogenation experiments.

[0034] Figure 2 This is a comparison of the fine Fe 2p spectra before and after regeneration in Example 1 using XPS.

[0035] Figure 3 The XRD patterns of Example 1, Comparative Example 1, and Comparative Example 3 are shown. The corresponding phase data are from the standard databases Al2O3 (PDF#00-10-0425), Fe2O3 (PDF#00-33-0664), CeO2 (PDF#00-043-1002), and KCl (PDF#00-041-1476).

[0036] Figure 4 The results are NH3-TPD characterization results for Example 1 and Comparative Example 2.

[0037] Figure 5 The XRD patterns of Example 1, Comparative Examples 4 and 5 are shown. The corresponding phase data are from the standard database for Al2O3 (PDF#00-10-0425) and K2Fe. 22 O 34 (PDF#00-031-1034), K2Fe4O7 (PDF#00-039-1106), CeO2 (PDF#00-043-1002) and KCl (PDF#00-041-1476).

[0038] Figure 6Thermogravimetric analysis curves of air after the catalyst reaction in Comparative Example 5 and Example 1 are shown. Detailed Implementation

[0039] Example 1

[0040] 1) Mix anhydrous ethanol and deionized water to prepare mixed solvent A. The volume of mixed solvent A is 30 mL, and the volume ratio of anhydrous ethanol to deionized water is 2:1.

[0041] 2) Dissolve 7.24g aluminum chloride hexahydrate, 0.34g ferric chloride hexahydrate, 0.34g potassium chloride and 0.23g cerium chloride heptahydrate in the mixed solvent A obtained in step 1), so that the theoretical content of each component in the resulting catalyst is Al2O3: 71%, Fe2O3: 12%, K2O: 12%, CeO2: 5%; heat and stir at 80℃ for 0.5h at a stirring speed of 300r / min to obtain mixed salt solution B;

[0042] 3) Cool the mixed salt solution B obtained in step 2) to room temperature, and add 18 mL of propylene oxide gelation accelerator to it at a constant rate of 5 mL / min per second under a 5°C ice-water bath and with thorough stirring to form a semi-gel.

[0043] 4) Transfer the semigel obtained in step 3) to a constant temperature bath and let it stand in a constant temperature water bath at 65℃ for 5 minutes to obtain wet gel precursor C;

[0044] 5) Add 10 ml of anhydrous ethanol to the wet gel precursor C obtained in step 4) for liquid sealing (use anhydrous ethanol to completely cover the surface of the wet gel precursor C) and age at room temperature for 36 h.

[0045] 6) After the aging in step 5) is completed, the wet gel precursor C is dried in an oven at 60°C for 12 hours, and then calcined in a muffle furnace at 800°C for 5 hours in air atmosphere with a heating rate of 2°C / min to obtain about 1.8g of the blocky solid iron catalyst, which is yellowish-brown in appearance; after crushing and sieving, 20-40 mesh catalyst is taken and used for the direct catalytic reaction of ethylbenzene.

[0046] The catalyst was used in the direct dehydrogenation reaction of ethylbenzene, and the product analysis method is as follows: Saturated ethylbenzene vapor at 76℃ was bubbled through a fixed-bed reactor bed with an inner diameter of 8 mm, using 10 mL / min high-purity nitrogen gas. The catalyst loading was 0.4 g, and the ethylbenzene space velocity was 1.0 h⁻¹. -1The reaction temperature was 600℃. The effluent was absorbed with ethanol, and its composition was analyzed using a Shimadzu GC-2010 gas chromatograph. The ethylbenzene conversion and styrene selectivity were calculated. Specifically, ethylbenzene conversion = (moles of ethylbenzene consumed / moles of ethylbenzene input); styrene selectivity = (moles of styrene produced / moles of ethylbenzene consumed).

[0047] For the catalyst of Example 1, the ethylbenzene conversion rate in the stable reaction section was measured to be 65%, the styrene selectivity to be 95%, and it could operate stably for more than 50 hours. The mass of carbon deposits on the catalyst surface was calculated based on the weight gain after the reaction. After 75 hours of operation, the catalyst of Example 1 had a weight gain of 0.08 g.

[0048] Example 2

[0049] Compared to Example 1, the only difference is that the proportions of aluminum, iron, potassium, and cerium in the raw materials remain unchanged, but the mass of the raw materials is reduced to half of the original (the theoretical percentage content of each metal in the obtained catalyst: Al2O3: 85.5%, Fe2O3: 6%, K2O: 6%, CeO2: 2.5%). The performance of the obtained catalyst was still tested using the method of Example 1. For the catalyst of Example 2, the measured ethylbenzene conversion rate in the stable reaction stage was 60%, the styrene selectivity was 92%, and it could operate stably for more than 50 hours.

[0050] Example 3

[0051] Compared to Example 1, the amounts of aluminum, iron, and cerium in the raw materials remained unchanged, but the mass of potassium was increased to 1.25 times that of Example 1 (the theoretical percentage content of each metal in the obtained catalyst: Al2O3: 68%, Fe2O3: 12%, K2O: 15%, CeO2: 5%). The performance of the obtained catalyst was still tested using the method of Example 1. For the catalyst of Example 3, the ethylbenzene conversion rate in the stable reaction section was measured to be 60%, the styrene selectivity was 95%, and it could operate stably for more than 50 hours.

[0052] Example 4

[0053] Compared to Example 1, the amounts of aluminum, iron, and cerium in the raw materials remained unchanged, but the mass of potassium was reduced to 0.75 times that of Example 1 (the theoretical percentage content of each metal in the obtained catalyst: Al2O3: 73%, Fe2O3: 12%, K2O: 9%, CeO2: 5%). The performance of the obtained catalyst was still tested using the method of Example 1. For the catalyst of Example 4, the measured ethylbenzene conversion rate in the stable reaction stage was 63%, the styrene selectivity was 93%, and it could operate stably for more than 40 hours.

[0054] Example 5

[0055] When the catalyst in Example 1 ran for more than 100 hours, the ethylbenzene conversion rate dropped below 50%. The ethylbenzene feed was then switched to air at a rate of 30 mL / min, while maintaining the reactor temperature. After 3 hours of air regeneration, the reactor was purged with nitrogen at a rate of 10 mL / min for 15 minutes, and then switched back to ethylbenzene feed. After 1 hour of adjustment, the ethylbenzene conversion rate recovered to 63%. When the ethylbenzene conversion rate dropped to 50% again, air regeneration was performed again to restore the conversion rate. Multiple cycles of air regeneration-ethylbenzene dehydrogenation experiments were conducted on the catalyst with a reaction time exceeding 280 hours. The results are shown in the attached figure. Figure 1 The study demonstrated the cyclic stability of the catalyst after air regeneration. This indicates that intermittent air regeneration is a feasible and efficient regeneration method. The valence state of XPS iron on the catalyst surface before and after regeneration was compared (see attached figure). Figure 2 ), Fe 3+ The increased content indicates that some Fe was reduced during the reaction. 3+ The catalyst is re-oxidized, which restores its activity.

[0056] Comparative Example 1

[0057] Compared to Example 1, the only difference was that the catalyst calcination temperature was set to 500℃; the resulting catalyst appeared identical to that of Example 1. The performance of the obtained catalyst was tested using the same method as in Example 1. For the catalyst of Comparative Example 1, the measured ethylbenzene conversion rate in the stable reaction stage was 45%, the styrene selectivity was 95%, and it could operate stably for more than 30 hours. However, we observed that the catalyst induction time was relatively long, exceeding 30 hours before reaching its maximum conversion rate. Combined with XRD results (see attached...). Figure 3 The spectrum in Comparative Example 1 shows a large peak, indicating that the catalyst structure is mainly amorphous. Under the calcination temperature conditions, the crystalline phase in the catalyst cannot be formed, resulting in a long activation induction period for the catalyst.

[0058] Comparative Example 2

[0059] Compared with Example 1, the only difference is that potassium salt was removed from the raw materials; the other preparation steps remained the same as in Example 1 (the theoretical percentage content of each metal in the obtained catalyst: Al2O3: 82%, Fe2O3: 13%, CeO2: 5%). The performance of the obtained catalyst was still tested using the method of Example 1. The measured performance of the catalyst was: ethylbenzene conversion 55%, styrene selectivity 92%, but the stabilization time was significantly shortened, and it could operate stably for 12 hours. Combined with the NH3-TPD characterization results (see attached...). Figure 4 When the catalyst lacks potassium, the catalyst is more acidic and has more acidic sites, which leads to a faster rate of coking and deactivation.

[0060] Comparative Example 3

[0061] Compared to Example 1, the only difference was that the amounts of aluminum, potassium, and cerium in the raw materials remained the same, but the mass of iron was increased to 1.5 times that of Example 1 (the theoretical percentage content of each metal in the obtained catalyst: Al2O3: 65%, Fe2O3: 18%, K2O: 12%, CeO2: 5%). The appearance of the prepared catalyst differed from that of Example 1, exhibiting a brick-red color. The performance of the obtained catalyst was still tested using the method of Example 1. For the catalyst of Comparative Example 3, the measured ethylbenzene conversion rate was approximately 40%, the styrene selectivity was 85%, and the reaction was only maintained for 20 hours. The catalyst bed was blocked by a large amount of coke generated during the reaction, and the reaction could not continue. Combined with the XRD results (see attached...) Figure 3 In Comparative Example 3, iron could not exist in a highly dispersed form, but instead formed an aggregated form of Fe2O3. As a result, the rate of catalyst coking was greatly accelerated, leading to the unstable operation of the ethylbenzene dehydrogenation reaction under this condition.

[0062] Comparative Example 4

[0063] Compared to Example 1, the difference lies in the addition of aluminum to the raw materials, while all other conditions remain unchanged. The resulting catalyst was tested using the same method as in Example 1, and the measured performance was: ethylbenzene conversion 45%, styrene selectivity 88%, and stable operation for 20 hours. XRD results are shown (see attached). Figure 5 The resulting catalyst contained only diffraction peaks of Al2O3.

[0064] Comparative Example 5

[0065] Currently, BASF catalysts are widely used in traditional ethylbenzene dehydrogenation industries. Under the same experimental conditions as in Example 1, the performance of the catalyst for direct ethylbenzene dehydrogenation was tested. The measured performance was: ethylbenzene conversion of 69% and styrene selectivity of 90%, but this could not be maintained for a long time; the conversion rate dropped rapidly after 20 hours. After 30 hours of operation, the catalyst weight increased by 0.18 g.

[0066] XRD analysis of the catalysts prepared by Example 1 and Comparative Example 5 (see attached) Figure 5 As can be seen, the iron catalyst prepared by the sol-gel method in this invention does not contain crystalline phases of iron species such as iron oxide, while Comparative Example 5 contains potassium polyferrates, such as K2Fe. 22 O 34 Therefore, the iron in this invention exists as a highly dispersed iron species in the alumina framework, and its catalytic mechanism is different from that of traditional iron oxide catalysts. As a result, the type and amount of coke produced are significantly different from those of traditional catalysts. The evidence is as follows: (1) The air thermogravimetric analysis curve of the catalyst of Example 1 after the reaction (attached) Figure 6(2) It can be seen that the air decomposition temperature range of the surface coke of the low-content iron gel catalyst of the present invention is 365~490℃, which is a type of coke that is easier to eliminate. In contrast, the air decomposition temperature range of the surface coke of the traditional iron oxide catalyst is 570~728℃, which is a type of coke that is more difficult to eliminate. (3) Comparing the surface coke amount of the catalyst of the present invention (Example 1) and the industrial BASF catalyst (Comparative Example 5), it can be seen that the catalyst weight gain of Example 1 after the reaction is lower than that of Comparative Example 5. According to the calculation, the styrene yield corresponding to each gram of coke on the iron catalyst of the present invention is 1843.2 mmol / g, which is higher than 926.0 mmol / g of Comparative Example 5, and therefore has better anti-coke properties.

[0067] The catalyst of this invention can perform a direct dehydrogenation reaction of ethylbenzene without water vapor during use, supplemented by a regeneration process of calcination and decarbonization by intermittent air introduction, thereby achieving the best overall energy-saving effect.

[0068] Comparing the above examples with the comparative examples, it can be seen that the process parameters (iron content, potassium content, and calcination temperature, etc.) in the sol-gel method preparation process are the key to obtaining the highly dispersed iron catalyst with high anti-coking performance in this invention.

Claims

1. The preparation of the highly dispersed and highly coking-resistant iron catalyst of the present invention adopts the sol-gel method, and the steps are as follows: 1) Prepare mixed solvent A by mixing anhydrous ethanol and deionized water; 2) Dissolve aluminum salt, iron salt, potassium salt and cerium salt in the mixed solvent A obtained in step 1), stir and heat to obtain mixed salt solution B; 3) Cool the mixed salt solution B obtained in step 2) to room temperature, and slowly add epoxy gelation accelerator dropwise at a constant rate under certain temperature and with thorough stirring to form a semi-gel. 4) Transfer the semigel obtained in step 3) to a constant temperature bath and further promote gel formation at a certain temperature to obtain wet gel precursor C; 5) Seal the wet gel precursor C obtained in step 4) with ethanol and age it at room temperature for a certain period of time. 6) After the wet gel precursor C from step 5) is aged, it is dried and calcined to obtain the highly dispersed and highly resistant to carbon deposition iron catalyst.

2. As described in claim 1, in step 2), the molar concentration of iron ions is 0.05~0.15 mol / L, the molar concentration of potassium ions is 0.1~0.2 mol / L, and the molar concentration of cerium ions is 0.02~0.04 mol / L.

3. As described in claim 1, in step 6), the drying temperature is 30~80℃, preferably 40~60℃; the calcination temperature is 600~900℃, preferably 700~800℃; the calcination atmosphere is pure oxygen or air atmosphere; and the calcination time is 1~8h, preferably 4~6h.

4. The content of each element in the catalyst prepared in step 6) as described in claim 1 is as follows: 64%~88% aluminum, calculated as Al2O3; 5%~15% iron, calculated as Fe2O3; Potassium content of 5% to 15%, calculated as K2O; 2% to 6% cerium, calculated as CeO2.

5. A highly dispersed iron catalyst with high resistance to coking, characterized in that: It is prepared by the preparation method described in any one of claims 1 to 4.

6. The application of the highly dispersed and highly coking-resistant iron catalyst of claim 5 in the direct dehydrogenation of ethylbenzene under anhydrous conditions. Its characteristics are: The reaction pressure is negative or atmospheric pressure, the reaction temperature is 575~610℃, and the ethylbenzene space velocity is 0.1~10h. -1 .

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