Cerium-Potassium-Iron Based Composite Oxide Catalyst, and Its Preparation and Application

Abstract

Cerium-Potassium-Iron Based Composite Oxide Catalyst, and Its Preparation and Application

Description

Cerium-Potassium-Iron Based Oxide Composite Catalyst, and Its Preparation and Application Cross-reference to related statements This application claims priority to a Chinese patent application No. 202011099425.4, entitled "Catalyst for producing styrene from ethylbenzene by dehydrogenation with low toluene by-product, preparation and use thereof, and method for dehydrogenating ethylbenzene", filed on October 14, 2020, the contents of which are incorporated herein by reference in their entirety. Technical background The present application relates to the technical field of dehydrogenation catalysts, in particular to an iron-potassium-cerium based composite oxide catalyst, its preparation and application. Pepshin's knowledge Catalytic dehydrogenation of ethylbenzene is a leading technical route for styrene production at home and abroad, and its production capacity accounts for about 85% of the total styrene production capacity. The main reaction of ethylbenzene dehydrogenation is C6H5-C2H5C6H5CH=CH2+H2+124KJ / mol, which is a strong endothermic reaction. Toluene and benzene are the main by-products, the benzene by-product must be separated by a rectification unit and then returned to the ethylbenzene unit for recycling, and the toluene with low economic value can only be sold as a by-product. Therefore, by reducing the production of benzene and toluene, the utilization of raw materials can be improved and the material consumption of the plant can be reduced. One of the key points of ethylbenzene dehydrogenation is the catalyst for styrene production by ethylbenzene dehydrogenation, which basically includes a main catalyst, a co-catalyst, a pore-forming agent, a reinforcing agent and the like. Fe-K-Ce series catalysts developed in the early 1980s show greatly improved activity while maintaining catalyst stability and preventing chromium oxides from polluting the environment, and are therefore used by styrene manufacturers around the world. CN104096568A is a composite oxide catalyst for the production of styrene by the dehydrogenation of ethylbenzene, comprising iron, potassium, magnesium, cerium and molybdenum oxides with the following mass percentages: 1) 68 to 75% iron oxide, calculated as Fe2O3; 2) 8 to 13% potassium oxide, calculated as K2O; 3) 0.5 to 6% magnesium oxide, calculated as MgO; 4) 8 to 15% cerium oxide, calculated as CeO2; 5) 1 to 6% molybdenum oxide, calculated as MoO3; and 6) 0.5 to 10% binder; wherein the iron oxide precursor comprises anhydrous iron oxide (e.g. red iron oxide) and hydrous iron oxide (i.e. yellow iron oxide), and the mass ratio of red iron oxide to yellow iron oxide is: red iron oxide : yellow iron oxide = 4.5 to 5.5 : 1; the potassium oxide precursor is potassium carbonate; the magnesium oxide is commercially available magnesium; the cerium oxide precursor is selected from cerium nitrate and nano cerium oxide, and the content of nano cerium oxide constitutes 10 to 50 mass percent, and preferably 25 to 40 mass percent, of the total amount of cerium oxide; the molybdenum oxide precursor is ammonium molybdate (NH4)6Mo7O24·4H2OThe binder may be at least one selected from kaolin, diatomite, cement and the like. However, the catalyst has a low ethylbenzene conversion of below 65% and a low styrene selectivity. The amount of by-product is an important indicator for evaluating the performance of the catalyst, and under the same conditions, catalysts with low by-products and good styrene selectivity are preferably used in styrene dehydrogenation processes. The catalysts disclosed in published US Patent Nos. US5190906A and US4804799A also have the problem of low styrene selectivity, and the styrene selectivity in the isothermal bed dehydrogenation reaction is usually lower than 95%, the total content of benzene and toluene in the product is greater than 4%, the material consumption is high, and the difficulty of subsequent separation is increased. US Patent No. US6177602A discloses a noble metal-containing iron oxide-based catalyst with which high selectivity can be achieved and the by-products of benzene and toluene are lower, but the cost of the catalyst is high due to the use of a noble metal catalyst, which poses a problem in industrial application. Industrial styrene production plants by ethylbenzene dehydrogenation in the world are mainly of the scale of 100,000 tons / year or above, with a maximum scale of 800,000 tons / year, and use high reaction temperatures, usually 620°C or above, and high steam-to-oil ratios, usually 1 / 3 (by weight) or above. High by-product generation, material consumption and energy consumption are always a difficult problem that styrene producers face. Therefore, developing a dehydrogenation catalyst with high selectivity and low by-product to significantly reduce material consumption and energy consumption is a difficult problem for styrene production by ethylbenzene dehydrogenation at present. Disclosure of the invention The present application aims to provide an iron-potassium-cerium based composite oxide catalyst, its preparation and application, which catalyst, when used for alkyl aromatic dehydrogenation, exhibits high selectivity, catalytic activity and stability even under conditions of low reaction temperature (e.g. not higher than 620°C) and very low steam-to-oil ratio, and has the advantages of less by-products of benzene and toluene, low material consumption and low energy consumption. To achieve the above object, in one aspect, the present application provides an iron-potassium-cerium-based composite oxide catalyst comprising a metal element M, in addition to the metal elements Fe, K and Ce, at least one of which is selected from the group consisting of Group IIA metal elements, Group VIB metal elements other than Cr, and Group IVA metal elements, wherein the catalyst has a total alkali content of 0.32 to 0.46 mmol / g and a strong alkali content of 0.061 to 0.082 mmol / g. In another aspect, a method for producing an iron-potassium-cerium-based composite oxide catalyst is provided in the present application, which comprises mixing an Fe source, a K source, a Ce source, an M source, optionally a source of a Group IVB metal element, optionally a source of a Group VA metal element, and optionally a ferrite, with a pore-forming agent and a solvent, and shaping, such as drying and / or calcining, to obtain the catalyst. In another aspect, the use of an iron-potassium-cerium based composite oxide catalyst is provided in the present application in the dehydrogenation of alkyl aromatics. In another aspect, the present application provides a process for the dehydrogenation of alkyl aromatics, comprising the step of contacting an alkyl aromatic hydrocarbon with an iron-potassium-cerium based composite oxide catalyst, which in the present application is under dehydrogenation conditions. When used for the dehydrogenation of alkyl aromatics, the catalyst of the present application exhibits strong catalytic activity, high selectivity and good stability even at low reaction temperatures and very low steam-to-oil ratios, and has the advantages of low material consumption and low energy consumption. Other features and benefits of the declaration will be explained in detail in the detailed description below. Brief description of the maps The drawings which form part of this specification are provided to aid in the understanding of this disclosure and are not to be construed as limiting. This disclosure may be interpreted by reference to the drawings in conjunction with the detailed description set forth below. In the drawings: Figure 1 shows the CO2-TPD patterns of the catalyst obtained in Example 1 of the present application before and after the reaction. Figure 2 shows the H2-TPR patterns of the catalysts obtained in Example 1 of the present application and Comparative Example 9. Figures A3 to D3 show SEM images of the catalysts obtained in Example 1 of the present application and Comparative Example 9 before and after the reaction. Detailed description of the invention The present declaration will be explained in detail below with reference to the drawing and specific examples thereof. It should be noted that the specific examples of the present declaration are provided for illustrative purposes only and are not limiting in any way. Any specific numerical value, including the endpoints of a numerical range, described in the context of the present application is not limited to its exact value, but should be interpreted to include all values ​​close to said exact value, e.g., all values ​​within ±5 percent of said exact value. Furthermore, with respect to any numerical range described herein, arbitrary combinations may be made between the endpoints of the range, between any endpoint and any specific value within the range, or between any two specific values ​​within the range to provide one or more new numerical range(s), where said new numerical range(s) should also be specifically described in the present application. Unless otherwise stated, terms used herein have the same meaning as commonly understood by those skilled in the art; and if terms are defined herein and their definitions differ from those commonly understood in the art, the definition provided herein shall govern. In this declaration, pressures given are gauge pressures unless otherwise specified. In the present declaration, the total alkali content and strong alkali content of the catalyst are measured according to the carbon dioxide temperature programmed desorption method (CO2-TPD method). Within the scope of the present disclosure, in addition to those expressly stated, any matter or matters not mentioned are considered to be, without modification, matters known in the art. Furthermore, any of the examples described herein may be freely combined with one or more other examples described herein, and the technical solutions or ideas obtained thereby are considered to be part of the main disclosure or description of the present disclosure and should not be considered as new matter not disclosed or anticipated herein, unless it is clear to those skilled in the art that such a combination is patently unreasonable. All patent and non-patent documents cited herein, including, but not limited to, textbooks and journal articles, are hereby incorporated by reference in their entirety. As described above, in a first aspect, the present application provides an iron-potassium-cerium-based composite oxide catalyst comprising, in addition to the metal elements Fe, K, and Ce, a metal element M, at least one of which is selected from the group consisting of Group IIA metal elements, Group VIB metal elements other than Cr, and Group IVA metal elements, wherein the catalyst has a total alkali content of from 0.32 to 0.46 mmol / g and a strong alkali content of from 0.061 to 0.082 mmol / g. In a preferred embodiment, the metal element M is a combination of at least two selected from the group consisting of Group IIA metal elements, Group VIB metal elements other than Cr, and Group IVA metal elements, preferably a combination of at least one Group IIA metal element, at least one Group VIB metal element other than Cr, and at least one Group IVA metal element. In a preferred embodiment, the Group IIA metal element present in the catalyst is not Mg, more preferably Sr. In a preferred embodiment, the Group VIB metal element present in the catalyst is not Cr or Mo, but is preferably W. In a preferred embodiment, the Group IVA metal element present in the catalyst is selected from Ge, Sn, and Pb, or a combination thereof. In a preferred embodiment, after 1500 hours of reaction under conditions including a pressure of -45 kPa, an ethylbenzene mass space velocity of 0.75 h-1, a temperature of 600°C, and a water to ethylbenzene weight ratio of 0.9, the catalyst crushing resistance retention rate is 80% or higher. In a preferred embodiment, after 1500 hours of reaction under conditions including a pressure of -45 kPa, an ethylbenzene mass space velocity of 0.75 h-1, a temperature of 600°C, and a water to ethylbenzene weight ratio of 0.9, the total alkali content retention rate of the catalyst is 82% or higher, and the strong alkali content retention rate of the catalyst is 80% or higher. In a preferred embodiment, the catalyst has a reduction completion temperature of 730°C or higher based on H2-TPR testing. In a preferred embodiment, the catalyst comprises 66 to 80 wt% Fe2O3 based on the total amount of catalyst, for example, the Fe2O3 weight content can be 66 wt%, 67 wt%, 68 wt%, 69 wt%, 70 wt%, 71 wt%, 72 wt%, 73 wt%, 74 wt%, 75 wt%, 76 wt%, 77 wt%, 78 wt%, 80 wt% or some amount between any two of them. In a preferred embodiment, the catalyst comprises 2.3 to 6 wt% K2O, preferably 2.3 to 5.5 wt% K2O, based on the total amount of catalyst, for example, the K2O content can be 2.3 wt%, 2.8 wt%, 3.3 wt%, 3.8 wt%, 3.4 wt%, 4.8 wt%, 3.5 wt%, 5.5 wt%, or some amount therebetween. In a preferred embodiment, the catalyst comprises 6 to 12 wt% CeO2, based on the total amount of catalyst, for example, 6 wt%, 6.5 wt%, 7 wt%, 7.5 wt%, 8 wt%, 8.5 wt%, 9 wt%, 9.5 wt%, 10 wt%, 10.5 wt%, 11 wt%, 11.5 wt%, 12 wt%, or some amount therebetween. In another preferred embodiment, the catalyst comprises 66 to 80 wt% Fe2O3, 2.3 to 6 wt% K2O, 6 to 12 wt% CeO2, and 2 to 16 wt% of the oxide of the metal element M, calculated as oxide based on the total amount of the catalyst. According to the present application, in the catalyst, the metal element M is usually present in the form of an oxide at its highest capacity. The inventors of the present application have found that within the content range described above, the catalyst of the present application exhibits better catalytic activity, higher selectivity, and better stability at low temperatures and very low steam-to-oil ratios, and produces less benzene and toluene. In addition, conventional catalysts have a K2O content of more than 10 wt%, which is easily destroyed during the catalytic dehydrogenation process, thereby reducing the activity of the catalyst; While the K2O content of the catalyst of the present application is 2.3 to 6 wt%, which is significantly lower than that of conventional catalysts.With such a very low K2O content, the catalyst of the present application still exhibits better catalytic activity, higher selectivity, and better stability, and produces less benzene and toluene by-products, and thus has higher application advantages compared to conventional catalysts. In a particularly preferred embodiment, the metal element oxide M is selected from at least one of WO3, SrO, or a Group IVA metal element oxide. With this preferred embodiment, the catalytic activity, selectivity, and stability of the catalyst can be further improved, and a smaller amount of benzene and toluene by-products can be obtained. In the present application, it is preferred that the metal element oxide M is at least two selected from WO3, SrO and an oxide of a Group IVA metal element, and where the metal element oxide M is at least two selected from WO3, SrO and an oxide of a Group IVA metal element, there is no particular limitation on the content of each component in the metal element oxide M, and the content of each component may be the same or different. As can be understood, where the oxide of the metal element M is a combination of two oxides selected from WO3, SrO, and an oxide of a metal element of Group IVA, the contents of the two oxides may be the same or different. Where the contents of the two oxides are different, the respective contents are not limited to the two oxides. Furthermore, preferably, the oxide of the metal element M is a combination of WO3, SrO, and an oxide of a metal element of Group IVA. In a preferred embodiment, the catalyst comprises 0.5 to 5 wt% WO3, based on the total amount of catalyst, for example, the WO3 content may be 0.5 wt%, 1 wt%, 1.5 wt%, 2 wt%, 2.5 wt%, 3 wt%, 3.5 wt%, 4 wt%, 4.5 wt%, 5 wt%, or some amount therebetween. In a preferred embodiment, the catalyst comprises 0.5 to 5 wt% SrO, based on the total amount of catalyst, and the SrO content can be 0.5 wt%, 1 wt%, 1.5 wt%, 2 wt%, 2.5 wt%, 3 wt%, 3.5 wt%, 4 wt%, 4.5 wt%, 5 wt%, or some amount therebetween. In a preferred embodiment, the catalyst comprises 0.5 to 5 weight percent of a Group IVA metal element oxide, based on the total amount of catalyst, e.g., 0.5 weight percent, 1 weight percent, 1.5 weight percent, 2 weight percent, 2.5 weight percent, 3 weight percent, 3.5 weight percent, 4 weight percent, 4.5 weight percent, 5 weight percent, or an amount therebetween. In another preferred embodiment, the catalyst comprises 67.5 to 79 wt% Fe2O3, 2.3 to 5.5 wt% K2O, 6 to 12 wt% CeO2, 0.5 to 5 wt% WO3, 0.5 to 5 wt% SrO, and 0.5 to 5 wt% oxide of a metal element of Group IVA, calculated as oxide and based on the total amount of the catalyst. Within the content range described above, the catalyst of the present application exhibits better catalytic activity, higher selectivity, and better stability at low temperatures and very low steam-to-oil ratios, and produces less benzene and toluene by-products. In a preferred embodiment, the Group IVA metal element oxide is selected from at least one of the group consisting of GeO2, SnO2, and PbO2. With this preferred embodiment, the catalytic activity and selectivity of the catalyst can be further improved, and a lower amount of benzene and toluene by-products can be obtained. In the present application, where the Group IVA metal element oxide is at least two selected from GeO2, SnO2, and PbO2, there is no particular limitation on the content of each component in the Group IVA metal element oxide, and the content of each component may be the same or different. As can be understood, where the oxide of the metal element of Group IVA is two elements selected from GeO2, SnO2 and PbO2, the contents of the two oxides may be the same or different. In cases where the contents of the two oxides are different, the respective contents of the two oxides are not limited, and preferably the ratio between the contents of the two oxides is 1:0.5 to 1.5, preferably 1:0.8 to 1.2 as the oxide and calculated based on the total amount of the oxide of the metal element of Group IVA. In another preferred embodiment, the Group IVA metal element oxide is a combination of GeO2, SnO2, and PbO2. As can be understood, where the Group IVA metal element oxide is a combination of GeO2, SnO2 and PbO2, the contents of the three oxides may be the same or different. In cases where the contents of the three oxides are different, the content of each of the three oxides is not limited, and preferably the ratio between the contents of the three oxides GeO2, SnO2 and PbO2 is 1:0.5 to 1:1.5, preferably 1:0.8 to 1 / 2, calculated as oxides and based on the total amount of the Group IVA metal element oxide. In a preferred embodiment, the catalyst further comprises a ferrite, such as manganese ferrite, zinc ferrite, copper ferrite, nickel ferrite and the like, preferably ZnFe2O4. The inventors of the present application have found through research that where a certain amount of Fe element is added in the form of ferrite, the resulting catalyst has higher activity, better selectivity, higher stability and less production of benzene and toluene by-products compared to the case where Fe element is simply added in the form of oxide, for example, adding ZnFe2O4 compared to adding an equivalent amount of ZnO and iron oxide. In a preferred embodiment, the catalyst comprises 0.5 to 8 wt% ferrite, preferably ZnFe2O4, based on the total amount of catalyst, e.g., 0.5 wt%, 1.5 wt%, 2.5 wt%, 3.5 wt%, 4.5 wt%, 5.5 wt%, 6.5 wt%, 7.5 wt%, 8 wt%, or some amount therebetween. In another preferred embodiment, the content of ferrite, such as ZnFe2O4, in the catalyst is 1 to 7 wt%, and more preferably 2 to 6 wt%, to further improve the catalytic activity, selectivity, and stability of the catalyst and to further reduce the production of benzene and toluene by-products. In a particularly preferred embodiment, the catalyst comprises 2 to 6 wt% ZnFe2O4, based on the total amount of catalyst, and the ZnFe2O4 content can be, for example, 2 wt%, 2.5 wt%, 3 wt%, 3.5 wt%, 4 wt%, 4.5 wt%, 5 wt%, 5.5 wt%, 6 wt%, or some amount therebetween. In a preferred embodiment, the catalyst may include other metal promoters, for example, Group IVB metal oxides, such as HfO2, and / or Group VA metal oxides, such as Sb2O5. Preferably, the catalyst comprises 0.05 to 0.5 weight percent of a Group IVB metal oxide, preferably HfO2, and / or 0.5 to 1.5 weight percent of a Group VA metal oxide, preferably Sb2O5, based on the total amount of catalyst. According to the present disclosure, to further improve the catalytic activity, selectivity and stability of the catalyst at low temperature and further reduce the production of benzene and toluene by-products, it is preferred that the catalyst does not contain molybdenum. According to the present disclosure, to further improve catalyst activity at low steam-to-oil ratios and reduce dehydrogenation temperatures, it is preferred that the catalyst does not contain magnesium. In a preferred embodiment, the catalyst does not include a binder such as montmorillonite, diatomite, cement, metahalosite, saponite, kaolin, halloysite, hydrotalcite, sepiolite, rectorite, attapulgite, bentonite, or any combination thereof. The inventors of the present application have found through research that adding a binder to the catalyst of the present application is not beneficial for improving the catalytic activity and stability of the catalyst, and that this preferred embodiment is more beneficial for improving the catalytic activity and stability of the catalyst. In a particular preferred embodiment, the catalyst of the present application comprises Fe element, K element, Ce element, and metal element M, and at least one of ZnFe2O4, HfO2, and Sb2O5, the metal element M being at least one of W element, Sr element, and Group IVA metal element. Further preferably, the catalyst comprises ZnFe2O4 and at least one of HfO2 and Sb2O5. The content of each element is as described above, the detailed description of which is omitted here for brevity. The inventors of the present application have found through research that in which the iron-potassium-cerium-based composite oxide catalyst is composed of the metal components defined above and has a total alkali content of from 0.32 to 0.46 mmol / g, together with a strong alkali content of from 0.061 to 0.082 mmol / g, the catalyst exhibits strong catalytic activity, high selectivity and good stability even at low reaction temperatures (e.g., not higher than 620°C) and very low steam-to-oil ratios when used for alkyl aromatic dehydrogenation. The above advantage in controlling the total alkali content and strong alkali content of catalysts for dehydrogenation of alkyl aromatics within the specific ranges described above has not been previously known in the art, and therefore there is no specific requirement for the total alkali content and strong alkali content of the catalyst and the stability of the alkali content during the reaction process in the prior art, and the total alkali content of existing catalysts is usually below 0.32 mmol / g. The catalyst of the present disclosure is provided with a total alkali content and a strong alkali content within a specific range by using a specific element coordination, which allows for reducing the input of low-yield materials, so that when the catalyst is used for the dehydrogenation of ethylbenzene, the production of benzene and toluene can be reduced, the selectivity of styrene and the utilization of raw materials can be improved, and a small fluctuation of alkali content before and after the reaction can be achieved.For example, the crushing strength of the catalyst obtained in the present application can reach 3.88 kg / mm, and in the activity evaluation on an isothermal fixed bed under conditions including pressure of -45 kPa, mass space velocity of ethylbenzene liquid of 0.75 h-1, reaction temperature of 600 °C and steam-to-oil ratio (i.e. weight ratio of water to ethylbenzene) of 0.9, the total content of benzene and toluene in the product can reach 2.26%, the selectivity of styrene can reach 17.97%, and the conversion of ethylbenzene can reach 6.77%; after 1500 hours of reaction, the total content of benzene and toluene in the product can reach 1.93%, the selectivity of styrene can reach 99.97%, and the conversion of ethylbenzene can reach 76.7%; And after 1500 hours of reaction, the retention rate of the total alkali content of the catalyst can reach 96.94%, the retention rate of the strong alkali content of the catalyst can reach 92.41%, and the retention rate of the crushing resistance of the catalyst can reach 94.85%, indicating good stability. In a preferred embodiment, the total alkali content of the catalyst is 0.32 to 0.42 mmol / g, preferably 0.324 to 0.397 mmol / g, particularly preferably 0.384 to 0.397 mmol / g, and may be, for example, 0.384 mmol / g, 0.386 mmol / g, 0.388 mmol / g, 0.39 mmol / g, 0.392 mmol / g, 0.394 mmol / g, 0.396 mmol / g, 0.397 mmol / g, or some amount therebetween. In a preferred embodiment, the strong alkali content of the catalyst is 0.061 to 0.080 mmol / g, preferably 0.061 to 0.079 mmol / g, particularly preferably 0.072 to 0.079 mmol / g, and may be, for example, 0.072 mmol / g, 0.074 mmol / g, 0.076 mmol / g, 0.078 mmol / g, 0.079 mmol / g, or some amount therebetween. In a particularly preferred embodiment, the catalyst of the present application has a total alkali content of 0.384 to 0.397 mmol / g and a strong alkali content of 0.072 to 0.079 mmol / g, in which case the catalyst of the present application exhibits better catalytic activity, higher selectivity, and better stability, and provides lower benzene and toluene content in the product under weak catalytic dehydrogenation conditions. In a second aspect, a method for producing an iron-potassium-cerium-based composite oxide catalyst is provided in the present application, which comprises mixing an Fe source, a K source, a Ce source, an M source, optionally a source of a Group IVB metal element, optionally a source of a Group VA metal element, and optionally a ferrite, with a pore-forming agent and a solvent, and shaping, optionally drying and / or calcining, to obtain the catalyst; wherein the source M is at least one of the group consisting of sources of Group IIA metal elements, sources of Group VIB metal elements other than Cr, and sources of Group IVA metal elements, preferably at least one of a source of W, a source of Sr, and a source of a Group IVA metal element, more preferably a combination of at least two sources of W, a source of Sr, and a source of a Group IVA metal element, and particularly preferably a combination of a source of W, a source of Sr, and at least one source of a selected Group IVA metal element. In the second aspect of the present disclosure, the Group IVB metal element, the Group VA metal element, ferrite, the Group IIA metal element, the Group VIB metal element other than Cr, the Group IVA metal element and the like are as defined above, the detailed description of which is omitted here for brevity. There is no particular limitation on the mixing mode in the method of the present disclosure, as long as the Fe source, K source, Ce source, M source, pore forming agent, solvent, optional Group IVB metal element source, optional Group VA metal element source and optional ferrite can be uniformly mixed. To further increase the catalytic activity and selectivity of the resulting catalyst and reduce the toluene content of the product at low temperature, in a preferred embodiment, the method of the present application comprises the following steps: 1) mixing an Fe source, a K source, a Ce source, an M source, optionally a source of a Group IVB metal element, and optionally a source of a Group VA metal element with a pore forming agent; 2) mixing the mixture obtained in step 1) with a ferrite, wherein the ferrite is preferably ZnFe2O4; and 3) Mixing the mixture obtained in step 2) with a solvent, shaping, and optionally drying and / or calcining to obtain the catalyst. In such a preferred embodiment, uniform mixing can be facilitated, catalytic activity, selectivity, and catalyst stability can be further improved, and the production of benzene and toluene by-products can be further reduced. In the preferred embodiment described above, there is no particular requirement on the mixing time of step 1), step 2) and step 3), which can be adjusted within a wide range as long as it enables the materials to be mixed uniformly in the additive order described above. Preferably, to save energy and ensure uniform mixing of the materials, the mixing time of step 1), step 2) and step 3) is independently 0.1 to 2 hours; more preferably, the mixing time of step 1) is 0.1 to 0.6 hours, the mixing time of step 2) is 1 to 2 hours and the mixing time of step 3) is 0.2 to 1 hour. In the method of the present application, the mixing mode can be selected within a wide range, and the mixing can be carried out, for example, under stirring conditions. The mixing can also be carried out in a mixer. In the present application, there is no particular limitation on the selection of the Fe source, which may be any iron-containing compound that can be converted into Fe2O3 in the subsequent calcination process. Preferably, the Fe source is red iron oxide and / or yellow iron oxide, more preferably a combination of red iron oxide and yellow iron oxide. In such a preferred embodiment, the catalytic activity and selectivity of the catalyst can be further improved, and the production of benzene and toluene by-products can be further reduced. In the present application, the ratio of red iron oxide to yellow iron oxide can be selected within a wide range, and preferably the weight ratio of red iron oxide to yellow iron oxide is 2 to 4:1, calculated as oxide; for example, it may be 2:1, 2 / 2:1, 2 / 4:1, 2 / 6:1, 2 / 8:1, 3:1, 3 / 2:1, 3 / 4:1, 3 / 6:1, 3 / 8:1, 4:1, or some amount between any two of them. In the present application, there is no particular limitation on the selection of the Ce source, which can be any cerium-containing compound that can be converted to CeO2 in a subsequent calcination process. Preferably, the Ce source is cerium hydroxide and / or cerium acetate. In such a preferred embodiment, environmental protection requirements (since nitrogen-containing gas is released during calcination of cerium nitrate) can be met, and the strength of the resulting catalyst can be further improved. In the present application, there is no particular limitation on the choice of the K source, which may be any potassium-containing compound that can be converted to K2O in a subsequent calcination process. Preferably, the K source is potassium carbonate and / or potassium bicarbonate; more preferably, potassium carbonate. In the present application, there is no particular limitation on the selection of the source of the Group VIB metal element, which may be any compound containing a Group VIB metal element that can be converted into a Group VIB metal oxide in a subsequent calcination process, and may be a salt containing a Group VIB metal element and / or a Group VIB metal element oxide. In the present application, there is no particular limitation on the selection of the W source, which may be any tungsten-containing compound that can be converted to WO3 in a subsequent calcination process, and preferably, the W source is at least one selected from the group consisting of ammonium tungstate, ammonium metatungstate, and tungsten trioxide; preferably ammonium tungstate. In the present application, there is no particular limitation on the selection of the source of the Group IIA metal element, which may be any compound containing a Group IIA metal element that can be converted into a Group IIA metal oxide in a subsequent calcination process, and the salt may contain a Group IIA metal element and / or a Group IIA metal element oxide. In the present application, there is no particular limitation on the selection of the Sr source, which may be any strontium-containing compound that can be converted to SrO in a subsequent calcination process, and preferably the Sr source is strontium carbonate and / or strontium hydroxide. In the present application, there is no particular limitation on the selection of the source of the Group IVA metal element, which may be any compound containing the Group IVA metal element that can be converted into the Group IVA metal oxide in the subsequent calcination process, and may be a salt containing the Group IVA metal element and / or an oxide of the Group IVA metal element. Preferably, the source of the Group IVA metal element is selected from oxides containing the Group IVA metal element. In the present application, there is no particular limitation on the selection of the source of the Group IVB metal element, which may be any compound containing a Group IVB metal element that can be converted into a Group IVB metal oxide in a subsequent calcination process, and may be a salt containing a Group IVB metal element and / or an oxide containing a Group IVB metal element. In the present application, there is no particular limitation on the selection of the Hf source, which may be any salt and / or oxide containing the element Hf that can be converted to hafnium oxide in the subsequent calcination process, preferably HfO2. In the present application, there is no particular limitation on the selection of the source of the VA group metal element, which may be any compound containing a VA group metal element that can be converted into a VA group metal oxide in the subsequent calcination process, and may be a salt containing a VA group metal element and / or an oxide containing a VA group metal element. In the present application, there is no particular limitation on the selection of the Sb source, which may be any salt and / or oxide containing the element Sb that can be converted to antimony oxide in the subsequent calcination process, preferably Sb2O5. In the present application, there is no particular limitation on the amount of the pore-forming agent added, and in order to provide a large specific surface area while ensuring the desired strength of the catalyst, it is preferred that the pore-forming agent be added in an amount of 2.2 to 3.6 wt%, preferably 3.8 to 6.5 wt%, based on the total amount of the Fe source, K source, Ce source, M source, optional ferrite, optional Group IVB metal element source, and optional Group VA metal element source. In the present application, there is no particular limitation on the type of pore-forming agent, which may be one commonly used in the art. Preferably, the pore-forming agent is at least selected from the group consisting of polystyrene, graphite, and cellulose and their derivatives. In the present application, graphite may be selected within a wide range and may be natural graphite or synthetic graphite without any particular limitation in the present application. Cellulose and its derivatives are preferably at least one of methylcellulose, hydroxymethylcellulose, ethylcellulose and sodium hydroxymethylcellulose. In a preferred embodiment of the present application, the pore-forming agent is at least one selected from the group consisting of graphite, polystyrene (which may be in the form of microspheres), and sodium carboxymethyl cellulose. In the present disclosure, there is no particular limitation on the amount of solvent added as long as the requirements for mixing the materials can be met. Preferably, the solvent is added in an amount of 15 to 35% by weight, preferably 22 to 32% by weight, based on the total weight of the catalyst raw materials. According to the present disclosure, the solvent may be chosen within a wide range, as long as it can provide a favorable environment for mixing and is preferably a water solvent. In the present application, there is no particular limitation on the shape of the catalyst, which may be, for example, a pellet, a rod or the like. A person skilled in the art can transform the mixed material obtained in step 3) into various usable sizes according to production requirements, for example, it may be extruded into pellets with a diameter of 3 mm and a length of 6 mm, but the present application is not limited thereto. In a preferred embodiment, the drying conditions of step 3) are: a temperature of 30 to 145°C, and a drying time of 1 to 8 hours; preferably the drying comprises: drying at a temperature of 35 to 95°C for 0.5 to 4 hours, followed by heating to 95 to 145°C and further drying for 0.5 to 4 hours. In a preferred embodiment, the calcination conditions of step 3) are: a temperature of 320 to 960°C, and a calcination time of 2 to 8 hours. Preferably, the calcination comprises: calcining at a temperature of 320 to 750°C for 1 to 4 hours, followed by further heating to 750 to 960°C and further calcining for 1 to 4 hours. In a third aspect, there is provided an iron-potassium-cerium based composite oxide catalyst obtained by the method of the present application. In a fourth aspect, the use of an iron-potassium-cerium based composite oxide catalyst is provided in the present application in the dehydrogenation of alkyl aromatics. In a fifth aspect, the present disclosure provides a process for the dehydrogenation of alkyl aromatics, comprising the step of contacting an alkyl aromatic hydrocarbon with an iron-potassium-cerium-based composite oxide catalyst of the present disclosure under dehydrogenation conditions. In a preferred embodiment, the alkyl aromatic hydrocarbon is one or more of the C8 to C10 alkylbenzenes, preferably ethylbenzene. When used for the dehydrogenation of alkyl aromatics, the catalyst of the present application exhibits higher catalytic activity, selectivity and stability, and provides low content of benzene and toluene by-products in the product, even at low temperatures and very low oil-to-steam ratios. In a preferred embodiment, the alkyl aromatic hydrocarbon dehydrogenation temperature may be 580 to 620°C, preferably 590 to 610°C, e.g., 590°C, 595°C, 600°C, 605°C or 610°C, or any value therebetween. According to the present disclosure, to further reduce material consumption, the mass space velocity of the alkyl aromatic hydrocarbon is preferably 0.5 to 1 h-1, more preferably 0.6 to 0.8 h-1, and may be, for example, 0.6 h-1, 0.65 h-1, 0.7 h-1, 0.75 h-1, 0.8 h-1, or any value therebetween. According to the present disclosure, to further reduce energy consumption, the weight ratio of water to alkyl aromatic hydrocarbon is preferably 0.7 to 1, and preferably 0.8 to 1, and may be, for example, 0.8, 0.82, 0.84, 0.86, 0.88, 0.9, 0.92, 0.94, 0.96, 0.98, 1, or any value therebetween. According to the present disclosure, the pressure for the alkyl aromatic hydrocarbon may be selected within a wide range, preferably the pressure may be from -60 kPa to atmospheric pressure, more preferably from -50 kPa to atmospheric pressure, and even more preferably from -50 kPa to -20 kPa, for example, -50 kPa, -48 kPa, -46 kPa, -44 kPa, -42 kPa, -40 kPa, -38 kPa, -36 kPa, -34 kPa, -32 kPa, -30 kPa, -28 kPa, -26 kPa, -24 kPa, -22 kPa, -20 kPa, or any value therebetween. In certain preferred embodiments, the dehydrogenation conditions may include: a temperature of 580 to 620°C, a mass space velocity of the alkyl aromatic hydrocarbon of 0.5 to 1 h-1, a weight ratio of water to alkyl aromatic hydrocarbon of 0.7 to 1, and a pressure of -60 kPa to atmospheric pressure; more preferably, the dehydrogenation conditions of the alkyl aromatic hydrocarbon include: a temperature of 590 to 610°C, a mass space velocity of 0.6 to 0.8 h-1, a weight ratio of water to alkyl aromatic hydrocarbon of 0.8 to 1, and a pressure of -50 kPa to atmospheric pressure. Examples The present declaration will be further explained by reference to the following examples, but the present declaration is not limited thereto. In the following examples and comparative examples, the catalyst performance was characterized by the conversion of ethylbenzene, the selectivity of styrene, and the contents of benzene and toluene in the product, respectively. Specifically, the catalyst performance was evaluated in an isothermal fixed bed, the process of which was summarized as follows: deionized water and ethylbenzene were respectively fed into a preheated mixer through a metering pump, mixed and preheated in a gas state, and then passed into a reactor, the reactor was heated to a predetermined temperature using electric heating wires, the reactor was a stainless steel tube with an inner diameter of 1 inch and was filled with 100 ml of catalyst, the reaction product exiting the reactor was condensed with water, and then the concentration of ethylbenzene (by weight percent), the concentration of styrene (by weight percent), and the concentrations of benzene and toluene (by weight percent) in the reaction product were analyzed by gas chromatography. Ethylbenzene conversion (percent) = (initial concentration of ethylbenzene in the reaction stream (wt%) - ethylbenzene concentration in the reaction product (wt%)) / initial concentration of ethylbenzene in the reaction stream (wt%); and Styrene selectivity (percent) = styrene concentration in the reaction product (wt%) / (initial ethylbenzene concentration in the reaction stream (wt%) - ethylbenzene concentration in the reaction product (wt%)). In the following examples and comparative examples, the total alkali content and strong alkali content of the catalyst were analyzed by the carbon dioxide temperature-programmed desorption method, in which 0.1 g of the catalyst was activated at 600°C for 2 hours in a helium gas stream, then cooled to 80°C and subjected to CO2 adsorption until equilibrium was reached, purged with helium gas to physically adsorb CO2, then heated from 80°C to 600°C at 10°C / min by the temperature-programmed method, the CO2-TPD pattern was recorded, and the desorbed CO2 was collected using liquid nitrogen at the same time, and the collected CO2 was quantitatively analyzed by gas chromatography. A typical CO2-TPD pattern is shown in Figure 1, where the peak in the low temperature region (80–400°C) is the desorption peak corresponding to weak alkali content, the peak in the high temperature region (400–600°C) is the desorption peak corresponding to strong alkali content.The desorbed CO2 was collected using liquid nitrogen during the recording of the CO2-TPD pattern, the amount of CO2 collected was quantitatively analyzed by gas chromatography, and the corresponding weak alkali content and strong alkali content were calculated. The total alkali content is the sum of the weak alkali content and the strong alkali content. The alkali content retention rate is the ratio of the alkali content after the reaction to the alkali content before the reaction. In the following examples and comparative examples, the electron microscope image of the catalyst was taken on a JSM-35 scanning electron microscope manufactured by Nippon electronics Co., Ltd., at working accelerating voltages of 15, 25 kV, at a working distance of 20 mm, a magnification of 20,000, and a resolution of 3.5 nm, respectively. In the following examples and comparative examples, the crushing resistance of the catalyst was measured according to HG / T2782-2011 using a particle intensity meter QCY-602. 40 granular test samples were taken by quartile method, and the crushing resistance of the sample was calculated as the arithmetic mean of the measured results. The crushing resistance retention rate is the ratio of the crushing resistance after reaction to the crushing resistance before reaction. In the following examples and comparative examples, the change in catalyst reduction temperature was observed using the temperature programmed reduction (TPR) method, in which a 50 mg sample of the catalyst was placed in a U-tube quartz reactor and heated to 400 °C in a helium atmosphere, and then cooled to room temperature, the atmosphere was changed to H2 / N2 reducing gas (with a H2 concentration of 10 vol%) to perform the programmed temperature reduction, and the temperature was increased to 850 °C at a rate of 10 °C / min. Example 1 2.55 parts by weight of red iron oxide, calculated as Fe2O3, 1.20 parts by weight of yellow iron oxide, calculated as Fe2O3, 4.66 parts by weight of potassium carbonate, calculated as K2O, 9.89 parts by weight of cerium acetate, calculated as CeO2, 2.61 parts by weight of ammonium tungstate, calculated as WO3, 2.38 parts by weight of strontium carbonate, calculated as SrO, 1.68 parts by weight of GeO2, 0.32 parts by weight of HfO2, and 5.69 parts by weight of sodium carboxymethyl cellulose (available from Shanghai Changguang Enterprise Development Co. Ltd.)., premium food products, which also applies below) were stirred in a mixer for 0.5 hours, 3.16 parts by weight of ZnFe2O4 was added thereto and stirred for another 1.5 hours, then deionized water was added in an amount of 26.3% by weight relative to the total weight of the catalyst raw materials, stirred and mixed for 0.5 hours, the product was taken out and extruded into granules with a diameter of 3 mm and a length of 6 mm, the granules were placed in an oven, dried at 55 ° C for 2 hours, heated to 135 ° C and dried for 3 hours, then placed in a muffle furnace, calcined at 455 ° C for 3 hours, then heated to 930 ° C and calcined for 3 hours to obtain a catalyst product whose composition is shown in Table 1. The change in the catalyst reduction temperature obtained in Example 1 was observed by the temperature programmed reduction (TPR) method and the H2-TPR pattern obtained is shown in Figure 2. From Figure 2, it can be seen that the catalyst reduction completion temperature (i.e., the temperature corresponding to the peak of the curve in the H2-TPR pattern) was 746 °C. 100 mL of the catalyst product obtained in this example was charged into a reactor and performance evaluation was carried out under conditions of -45 kPa, a mass space velocity of 0.75 h-1, 600°C and a steam to ethylbenzene weight ratio of 0.9, and the test results obtained after 100 hours and 1500 hours of reaction are shown in Table 5. The total alkali content and strong alkali content of the catalyst obtained in Example 1 were analyzed before the reaction and after 1500 hours of reaction by the carbon dioxide temperature programmed desorption method, and the obtained CO2-TPD pattern is shown in Figure 1. In Figure 1, the peak in the low temperature region is the desorption peak corresponding to the weak alkali content, and the peak in the high temperature region is the desorption peak corresponding to the strong alkali content. The desorbed CO2 was collected using liquid nitrogen while recording the CO2-TPD pattern, the amount of the collected CO2 was quantitatively analyzed by gas chromatography, and the corresponding weak alkali content and strong alkali content were calculated. The total alkali content is the sum of the weak alkali content and the strong alkali content. The strong alkali content and total alkali content before and after the reaction of the catalyst obtained in Example 1 and the retention rate of the alkali content are shown in Table 4. The catalyst obtained in Example 1 has a crushing strength of 3.35 kg / mm ​​before reaction, a strength of 2.88 kg / mm ​​after reaction, and a retention rate of 85.97%, as measured by the HG / T2782-2011 method, and the results are shown in Table 4. An electron microscope image of the catalyst was taken on a scanning electron microscope, and the scanning electron microscope (SEM) images of the catalyst obtained in Example 1 before and after the reaction are shown in Figures A3 and B3, respectively. Comparative Example 1 A catalyst was prepared as described in Example 1, except that ZnFe2O4 and GeO2 were not added, specifically: 58.01 parts by weight of red iron oxide, calculated as Fe2O3, 21.12 parts by weight of yellow iron oxide, calculated as Fe2O3, 4.9 parts by weight of potassium carbonate, calculated as K2O, 10.39 parts by weight of cerium acetate, calculated as CeO2, 2.74 parts by weight of ammonium tungstate, calculated as WO3, 2.5 parts by weight of strontium carbonate, calculated as SrO, 0.34 parts by weight of HfO2, and 5.69 parts by weight of sodium carboxymethyl cellulose were stirred in a mixer for 20 hours, deionized water was added in an amount of 26.3% by weight relative to the total weight of the catalyst raw materials and mixed for 0.5 hours, the product was taken out and extruded into granules with a diameter of 3 mm and a length of 6 mm, the granules were placed in an oven were added, dried at 55 °C for 2 h, heated to 135 °C and dried for 3 h, then placed in a muffle furnace, calcined at 455 °C for 3 h, and then calcined at 930 °C for 3 h to obtain the catalytic product whose composition is shown in Table 1. The catalyst was evaluated and analyzed as described in Example 1, the results of the alkali content analysis and strength measurement are shown in Table 4 and the evaluation results are shown in Table 5. Comparative Example 2 A catalyst was prepared, evaluated and analyzed as described in Example 1, except that ZnFe2O4 was not added, but was replaced with red iron oxide, yellow iron oxide and ZnO with equivalent elemental oxide amounts, the relative proportions of the remaining components, the preparation of the catalyst. The method and conditions of the catalyst evaluation and the analysis method were the same as in Example 1. The composition of the catalyst is shown in Table 1, the results of the alkali content analysis and strength measurement are shown in Table 4, and the evaluation results are shown in Table 5. Example 2 A catalyst was prepared, evaluated and analyzed as described in Example 1, except that SnO2 was used instead of GeO2. The catalyst composition is shown in Table 1, the results of the alkali content analysis and strength measurements are shown in Table 4, and the evaluation results are shown in Table 5. Comparative Example 3 A catalyst was prepared, evaluated and analyzed as described in Example 1, except that SnO2 was used instead of GeO2, ZnFe2O4 was not added but was replaced by red iron oxide, yellow iron oxide and ZnO with equivalent elemental oxide amounts, calculated as oxide. The catalyst composition is shown in Table 1, the results of the alkali content analysis and resistance measurements in Table 4 and the evaluation results in Table 5. Example 3 A catalyst was prepared, evaluated and analyzed as described in Example 1, except that PbO2 was used instead of GeO2. The catalyst composition is shown in Table 1, the results of the alkali content analysis and strength measurements are shown in Table 4, and the evaluation results are shown in Table 5. Comparative Example 4 A catalyst was prepared, evaluated and analyzed as described in Example 1, except that PbO2 was used instead of GeO2, ZnFe2O4 was not added but was replaced by red iron oxide, yellow iron oxide and ZnO with equivalent elemental oxide amounts, calculated as oxide. The catalyst composition is shown in Table 1, the results of the alkali content analysis and strength measurements are shown in Table 4 and the evaluation results are shown in Table 5. Example 4 A catalyst was prepared, evaluated and analyzed as described in Example 1, except that 0.84 parts by weight of GeO2 and 0.84 parts by weight of SnO2 were used instead of 1.68 parts by weight of GeO2. The catalyst composition is shown in Table 1, the results of the alkali content analysis and strength measurements are shown in Table 4, and the evaluation results are shown in Table 5. Example 5 A catalyst was prepared, evaluated and analyzed as described in Example 1, except that 0.84 parts by weight of GeO2 and 0.84 parts by weight of PbO2 were used instead of 1.68 parts by weight of GeO2. The catalyst composition is shown in Table 1, the results of the alkali content analysis and strength measurements are shown in Table 4, and the evaluation results are shown in Table 5. Example 6 A catalyst was prepared, evaluated and analyzed as described in Example 1, except that 0.84 parts by weight of SnO2 and 0.84 parts by weight of PbO2 were used instead of 1.68 parts by weight of GeO2. The catalyst composition is shown in Table 1, the results of the alkali content analysis and strength measurements are shown in Table 4, and the evaluation results are shown in Table 5. Example 7 A catalyst was prepared, evaluated, and analyzed as described in Example 1, except that 0.56 parts by weight of GeO2, 0.56 parts by weight of SnO2, and 0.56 parts by weight of PbO2 were used instead of 1.68 parts by weight of GeO2. The catalyst composition is shown in Table 1, the results of the alkali content analysis and strength measurements are shown in Table 4, and the evaluation results are shown in Table 5. Example 8 54.01 parts by weight of red iron oxide, calculated as Fe2O3, 16.9 parts by weight of yellow iron oxide, calculated as Fe2O3, 2.37 parts by weight of potassium carbonate, calculated as K2O, 11.84 parts by weight of cerium acetate, calculated as CeO2, 4.16 parts by weight of ammonium tungstate, calculated as WO3, 3.35 parts by weight of strontium carbonate, calculated as SrO, 0.85 parts by weight of GeO2, 0.06 parts by weight of HfO2, 0.96 parts by weight of Sb2O5 and 5.69 parts by weight of sodium carboxymethyl cellulose were stirred in a mixer for 1 hour, 5.5 parts by weight of ZnFe2O4 was added to it and then stirred for 2 hours, deionized water was added in an amount of 15% by weight relative to the weight All catalyst raw materials were added, stirred and mixed for 1 hour, the product was taken out and extruded into pellets with a diameter of 3 mm and a length of 6 mm, the pellets were placed in an oven, dried at 30 °C for 4 hours, then dried at 95 °C for 4 hours, placed in a muffle furnace, calcined at 320 °C for 4 hours, and then calcined at 750 °C for 4 hours.hours to obtain the catalytic product whose composition is shown in Table 1. A catalyst was prepared, evaluated and analyzed as described in Example 1, the results of alkali content analysis and strength measurements are shown in Table 4 and the evaluation results are shown in Table 5. Example 9 52.62 parts by weight of red iron oxide, calculated as Fe2O3, 13.45 parts by weight of yellow iron oxide, calculated as Fe2O3, 4.66 parts by weight of potassium carbonate, calculated as K2O, 10.55 parts by weight of cerium hydroxide, calculated as CeO2, 1.72 parts by weight of ammonium tungstate, calculated as WO3, 4.83 parts by weight of strontium carbonate, calculated as SrO, 4.4 parts by weight of GeO2, 0.12 parts by weight of HfO2, and 5.69 parts by weight of sodium carboxymethyl cellulose were stirred in a mixer for 0.4 hours, 7.65 parts by weight of ZnFe2O4 was added to it and then stirred for 1 hour, deionized water was added in an amount of 35% by weight based on the total weight of the catalyst raw materials to It was added, mixed for 1 hour, the result was taken out and extruded into pellets of 3 mm diameter and 6 mm length, the pellets were placed in an oven, dried at 95 °C for 0.5 h and further dried at 145 °C for 0.5 h, then placed in a muffle furnace, calcined at 750 °C for 1 h, and then further at 960 °C.They were calcined for 1 hour to obtain the catalytic product whose composition is shown in Table 1. A catalyst was prepared, evaluated and analyzed as described in Example 1, the results of alkali content analysis and strength measurements are shown in Table 4 and the evaluation results are shown in Table 5. Example 10 36.55 parts by weight of red iron oxide, calculated as Fe2O3, 17.42 parts by weight of yellow iron oxide, calculated as Fe2O3, 3.71 parts by weight of potassium carbonate, calculated as K2O, 9.01 parts by weight of cerium acetate, calculated as CeO2, 4.82 parts by weight of ammonium tungstate, calculated as WO3, 1.83 parts by weight of strontium carbonate, calculated as SrO, 4.58 parts by weight of GeO2, 0.45 parts by weight of HfO2, and 5.69 parts by weight of sodium carboxymethyl cellulose were stirred in a mixer for 0.5 hours, 2.82 parts by weight of ZnFe2O4 was added to it and then stirred for 1.5 hours, deionized water was added in an amount of 26.3% by weight of the total weight of the raw materials. The catalyst was added, mixed for 0.5 h, the product was decanted and extruded into pellets of 3 mm diameter and 6 mm length, the pellets were placed in an oven, dried at 55 °C for 2 h, then dried at 135 °C for 3 h, placed in a muffle furnace, calcined at 455 °C for 3 h, and then calcined at 930 °C for 3 h.were used to obtain a catalytic product whose composition is shown in Table 2. A catalyst was prepared, evaluated and analyzed as described in Example 1, the results of alkali content analysis and strength measurements are shown in Table 4 and the evaluation results are shown in Table 5. Example 11 60.69 parts by weight of red iron oxide, calculated as Fe2O3, 17.36 parts by weight of yellow iron oxide, calculated as Fe2O3, 5.05 parts by weight of potassium carbonate, calculated as K2O, 6.15 parts by weight of cerium acetate, calculated as CeO2, 1.78 parts by weight of ammonium tungstate, calculated as WO3, 0.55 parts by weight of strontium carbonate, calculated as SrO, 2.02 parts by weight of GeO2, 0.25 parts by weight of HfO2 and 5.69 parts by weight of sodium carboxymethyl cellulose were stirred in a mixer for 0.5 hours, 6.15 parts by weight of ZnFeO24 was added to it and then stirred for 1.5 hours, deionized water was added in an amount of 26.3% by weight relative to the total weight of the raw materials. The catalyst was added, and mixed for 0.5 h, the product was taken out and extruded into pellets with a diameter of 3 mm and a length of 6 mm, the pellets were placed in an oven, dried at 55 °C for 2 h, and then dried at 135 °C for 3 h, then placed in a muffle furnace, calcined at 455 °C for 3 h, and then at 930 °C for 3 h.They were calcined to obtain the catalytic product, the composition of which is shown in Table 2. A catalyst was prepared, evaluated and analyzed as described in Example 1, the results of alkali content analysis and strength measurements are shown in Table 4 and the evaluation results are shown in Table 5. Comparative Example 5 4.54 parts by weight of red iron oxide, calculated as Fe2O3, 1.21 parts by weight of yellow iron oxide, calculated as Fe2O3, 4.77 parts by weight of potassium carbonate, calculated as K2O, 4.55 parts by weight of K2SiO3, 7.75 parts by weight of cerium acetate, calculated as CeO2, 2.58 parts by weight of ammonium tungstate, calculated as WO3, 1.38 parts by weight of strontium carbonate, calculated as SrO, 1.48 parts by weight of GeO2, 0.02 parts by weight of HfO2, and 5.69 parts by weight of sodium carboxymethyl cellulose were stirred in a mixer for 0.5 hours, 3.74 parts by weight of ZnFe2O4 was added to it and then stirred for 1.5 hours, deionized water was added in an amount 26.3% by weight of the total weight of the catalyst raw materials was added, mixed for 0.5 hours, the product was taken out and extruded into pellets with a diameter of 3 mm and a length of 6 mm, the pellets were placed in a furnace, dried at 55 °C for 2 hours, and then dried at 135 °C for 3 hours, placed in a muffle furnace, and calcined at 455 °C for 3 hours, and then at 930 °C.They were calcined at 100 °C for 3 h to obtain the catalytic product, the composition of which is shown in Table 2. A catalyst was prepared, evaluated and analyzed as described in Example 1, the results of alkali content analysis and strength measurements are shown in Table 4 and the evaluation results are shown in Table 5. Comparative Example 6 42.9 parts by weight of red iron oxide, calculated as Fe2O3, 25.8 parts by weight of yellow iron oxide, calculated as Fe2O3, 5.8 parts by weight of potassium carbonate, calculated as K2O, 1.9 parts by weight of cerium acetate, calculated as CeO2, 2.5 parts by weight of ammonium tungstate, calculated as WO3, 1.4 parts by weight of strontium carbonate, calculated as SrO, 4.77 parts by weight of GeO2, 0.13 parts by weight of HfO2, and 5.69 parts by weight of sodium carboxymethyl cellulose were stirred in a mixer for 0.5 hours, 4.9 parts by weight of ZnFeO24 was added thereto and stirred for 1.5 hours, deionized water was added to it in an amount of 26.3% by weight relative to the total weight of the catalyst raw materials, and for The mixture was mixed for 0.5 h, the product was extruded into pellets with a diameter of 3 mm and a length of 6 mm, and the pellets were placed in an oven, dried at 55 °C for 2 h, and then dried at 135 °C for 3 h, then placed in a muffle furnace, calcined at 455 °C for 3 h, and then calcined at 930 °C for 3 h.were used to obtain a catalytic product whose composition is shown in Table 2. A catalyst was prepared, evaluated and analyzed as described in Example 1, the results of alkali content analysis and strength measurements are shown in Table 4 and the evaluation results are shown in Table 5. Comparative Example 7 54.8 parts by weight of red iron oxide, calculated as Fe2O3, 16.04 parts by weight of yellow iron oxide, calculated as Fe2O3, 5.85 parts by weight of potassium carbonate, calculated as K2O, 7.11 parts by weight of CeO2, 4.42 parts by weight of ammonium tungstate, calculated as WO3, 3.35 parts by weight of strontium carbonate, calculated as SrO, 3.85 parts by weight of GeO2, 0.99 parts by weight of MoO3, 0.09 parts by weight of HfO2, and 5.69 parts by weight of sodium carboxymethyl cellulose were stirred in a mixer for 0.5 hours, 3.5 parts by weight of ZnFe2O4 was added to it and then stirred for 1.5 hours, deionized water was added in an amount of 26.3% by weight of the total weight of the raw materials. The catalyst was added, mixed for 0.5 h, the product was taken out and extruded into pellets with a diameter of 3 mm and a length of 6 mm, the pellets were placed in an oven, dried at 55 °C for 2 h, and then dried at 135 °C for 3 h, placed in a muffle furnace, and calcined at 455 °C for 3 h, and then dried at 930 °C for 3 h to obtain the product.A catalyst is obtained whose composition is shown in Table 2. A catalyst was prepared, evaluated and analyzed as described in Example 1, the results of alkali content analysis and strength measurements are shown in Table 4 and the evaluation results are shown in Table 5. Comparative Example 8 50.5 parts by weight of red iron oxide, calculated as Fe2O3, 17.01 parts by weight of yellow iron oxide, calculated as Fe2O3, 4.66 parts by weight of potassium carbonate, calculated as K2O, 6.15 parts by weight of cerium acetate, calculated as CeO2, 3.29 parts by weight of ammonium tungstate, calculated as WO3, 2.73 parts by weight of strontium carbonate, calculated as SrO, 4.53 parts by weight of GeO2, 0.75 parts by weight of HfO2, 1.2 parts by weight of cement, and 5.69 parts by weight of sodium carboxymethyl cellulose were stirred in a mixer for 0.5 hours, 8.28 parts by weight of ZnFeO24 was added to it and then stirred for 1.5 hours, deionized water was added to the amount of 26.3% by weight. The raw materials were added to it in proportion to the total weight of the catalyst, mixed for 0.5 hours, the product was taken out and extruded into granules with a diameter of 3 mm and a length of 6 mm, the granules were placed in an oven, dried at 55 °C for 2 hours, and then dried at 135 °C for 3 hours, then placed in a muffle furnace, calcined at 455 °C for 3 hours, and then calcined at 930 °C toThey were calcined for 3 hours to obtain the catalytic product, the composition of which is shown in Table 2. A catalyst was prepared, evaluated and analyzed as described in Example 1, the results of alkali content analysis and strength measurements are shown in Table 4 and the evaluation results are shown in Table 5. Example 12 48.01 parts by weight of red iron oxide, calculated as Fe2O3, 20.4 parts by weight of yellow iron oxide, calculated as Fe2O3, 35.5 parts by weight of potassium carbonate, calculated as K2O, 11.15 parts by weight of cerium acetate, calculated as CeO2, 0.91 parts by weight of ammonium tungstate, calculated as WO3, 4.85 parts by weight of strontium carbonate, calculated as SrO, 4.4 parts by weight of SnO2, 0.28 parts by weight of HfO2, and 5.69 parts by weight of sodium carboxymethyl cellulose were stirred for 5 hours, 4.65 parts by weight of ZnFe2O4 was added to it and then stirred for 1.5 hours, deionized water was added to it in an amount of 26.3% by weight relative to the total weight of the catalyst raw materials, for The mixture was mixed for 0.5 hours, the product was taken out and extruded into pellets with a diameter of 3 mm and a length of 6 mm, the pellets were placed in an oven, dried at 55 °C for 2 hours, and then dried at 135 °C for 3 hours, then placed in a muffle furnace, calcined at 455 °C for 3 hours, and then calcined at 930 °C for 3 hours to obtain the product.A catalyst is obtained whose composition is shown in Table 2. A catalyst was prepared, evaluated and analyzed as described in Example 1, the results of alkali content analysis and strength measurements are shown in Table 4 and the evaluation results are shown in Table 5. Example 13 52.7 parts by weight of red iron oxide, calculated as Fe2O3, 2.25 parts by weight of yellow iron oxide, calculated as Fe2O3, 5.05 parts by weight of potassium carbonate, calculated as K2O, 8.99 parts by weight of cerium acetate, calculated as CeO2, 2.58 parts by weight of ammonium tungstate, calculated as WO3, 1.38 parts by weight of strontium carbonate, calculated as SrO, 2.89 parts by weight of PbO2, 0.26 parts by weight of HfO2, and 5.69 parts by weight of sodium carboxymethyl cellulose were stirred in a mixer for 0.5 hours, 0.95 parts by weight of ZnFeO24 was added to it and then stirred for 1.5 hours, deionized water was added in an amount of 26.3% by weight based on the total weight of the catalyst raw materials. was added, mixed for 0.5 h, the product was removed and extruded into pellets of 3 mm diameter and 6 mm length, the pellets were placed in an oven, dried at 55 °C for 2 h, and then dried at 135 °C for 3 h, then placed in a muffle furnace, calcined at 455 °C for 3 h, and then at 930 °C for 3 h.They were calcined to obtain the catalytic product, the composition of which is shown in Table 2. A catalyst was prepared, evaluated and analyzed as described in Example 1, the results of alkali content analysis and strength measurements are shown in Table 4 and the evaluation results are shown in Table 5. Example 14 25.54 parts by weight of red iron oxide, calculated as Fe2O3, 18.42 parts by weight of yellow iron oxide, calculated as Fe2O3, 19.5 parts by weight of potassium carbonate, calculated as K2O, 15.9 parts by weight of cerium acetate, calculated as CeO2, 3.22 parts by weight of ammonium tungstate, calculated as WO3, 2.69 parts by weight of strontium carbonate, calculated as SrO, 3.95 parts by weight of GeO2, 0.48 parts by weight of HfO2, and 5.69 parts by weight of sodium carboxymethyl cellulose were mixed in a mixer for 0.5 hours, 2.65 parts by weight of NiFe2O4 was added to it and then stirred for 1.5 hours, deionized water was added in an amount of 26.3% by weight based on the total weight of the catalyst raw materials. It was added, mixed for 0.5 h, the product was taken out and extruded into pellets with a diameter of 3 mm and a length of 6 mm, the pellets were placed in an oven, dried at 55 °C for 2 h, and then dried at 135 °C for 3 h, and then placed in a muffle furnace, which was calcined at 455 °C for 3 h, and then calcined at 930 °C forThey were calcined for 3 hours to obtain the catalytic product, the composition of which is shown in Table 2. A catalyst was prepared, evaluated and analyzed as described in Example 1, the results of alkali content analysis and strength measurements are shown in Table 4 and the evaluation results are shown in Table 5. Comparative Example 9 A catalyst was prepared as described in Example 1, except that ZnFe2O4 was stirred together with red iron oxide, yellow iron oxide, potassium carbonate, cerium acetate, ammonium tungstate, strontium carbonate, GeO2, HfO2, and sodium carboxymethyl cellulose for 2 hours, deionized water was added in an amount of 26.3 wt% based on the total weight of the catalyst raw materials, stirred and mixed for 0.5 hours, and the ratio of other added components and other preparation steps were as in Example 1. The H2-TPR pattern of the obtained catalyst is shown in Figure 2, the electron microscope images of the catalyst before and after the reaction are shown in Figure C3 and Figure D3, respectively, and the analysis method was the same as in Example 1. As can be seen from Figure 2, the reduction completion temperature of the catalyst obtained in Comparative Example 9 was 674°C, and the reduction completion temperature of the catalyst obtained in Example 1 was 72°C higher than that of Comparative Example 9, indicating that the catalyst obtained in Example 1 has better reduction resistance. As can be seen from Figures A3 and B3, after 1500 hours of reaction, the surface particles of the catalyst obtained in Example 1 still have clear lines and are uniformly distributed; in contrast, as can be seen from Figures C3 and D3, the catalyst obtained in Comparative Example 9 shows a sintering phenomenon and obvious growth of particles on the surface after reaction, indicating that the catalyst obtained in Example 1 has better stability. A catalyst was prepared, evaluated and analyzed as described in Example 1, the results of alkali content analysis and strength measurements are shown in Table 4 and the evaluation results are shown in Table 5. Comparative Example 10 A catalyst was prepared as described in Example 1, except that 8.88 parts by weight of cerium acetate, calculated as CeO2, was added, and at the same time, magnesium hydroxide was also added in an amount equivalent to 1.01 part by weight of MgO, and the proportions of the other added components and the other preparation steps were as in Example 1. A catalyst was prepared, evaluated and analyzed as described in Example 1, the results of alkali content analysis and strength measurements are shown in Table 4 and the evaluation results are shown in Table 5. Comparative Example 11 4.54 parts by weight of red iron oxide, calculated as Fe2O3, 1.21 parts by weight of yellow iron oxide, calculated as Fe2O3, 2.61 parts by weight of potassium carbonate, calculated as K2O, 4.55 parts by weight of K2ZnO2, 10.26 parts by weight of cerium acetate, calculated as CeO2, 2.58 parts by weight of ammonium tungstate, calculated as WO3, 1.38 parts by weight of strontium carbonate, calculated as SrO, 3.74 parts by weight of ZnFe2O4, 1.48 parts by weight of GeO2, 0.02 parts by weight of HfO2, and 5.69 parts by weight of sodium carboxymethyl cellulose were stirred in a mixer for 1.5 hours, deionized water was added in an amount of 26.3% by weight based on the total weight of the catalyst raw materials. The mixture was stirred for 0.5 h, the product was extruded into pellets with a diameter of 3 mm and a length of 6 mm, the pellets were placed in a furnace, dried at 60 °C for 2 h, and then dried at 130 °C for 3 h, then placed in a muffle furnace, calcined at 650 °C for 3 h, and then calcined at 920 °C for 3 h to obtain the product.A catalyst is obtained whose composition is shown in Table 2. A catalyst was prepared, evaluated and analyzed as described in Example 1, the results of alkali content analysis and strength measurements are shown in Table 4 and the evaluation results are shown in Table 5. Comparative Example 12 49.7 parts by weight of red iron oxide, calculated as Fe2O3, 19.5 parts by weight of yellow iron oxide, calculated as Fe2O3, 5.81 parts by weight of potassium carbonate, calculated as K2O, 5.73 parts by weight of K2SiO3, 11.23 parts by weight of cerium nitrate, calculated as CeO2, 0.74 parts by weight of ammonium tungstate, calculated as WO3, 4.27 parts by weight of magnesium hydroxide, calculated as MgO, 0.85 parts by weight of SrO, 1.98 parts by weight of Eu2O3, 0.19 parts by weight of GeO2, and 5.69 parts by weight of graphite were stirred in a mixer for 1.5 hours. Deionized water was added to it in an amount of 26.3% by weight relative to the total weight of the catalyst raw materials. The mixture was stirred for 0.5 hours. The resulting product was extruded into pellets with a diameter of 3 mm and a length of 6 mm. The pellets were placed in a furnace, dried at 60 °C for 2 h, then dried at 130 °C for 3 h, then placed in a muffle furnace, calcined at 650 °C for 3 h, and then calcined at 920 °C for 3 h to obtain a catalytic product thatIts composition is shown in Table 3. A catalyst was prepared, evaluated and analyzed as described in Example 1, the results of alkali content analysis and strength measurements are shown in Table 4 and the evaluation results are shown in Table 5. Comparative Example 13 2.50 parts by weight of red iron oxide, calculated as Fe2O3, 0.19 parts by weight of yellow iron oxide, calculated as Fe2O3, 5.81 parts by weight of potassium carbonate, calculated as K2O, 5.73 parts by weight of K2ZnO2, 11.23 parts by weight of cerium nitrate, calculated as CeO2, 0.74 parts by weight of ammonium tungstate, calculated as WO3, 4.27 parts by weight of magnesium hydroxide, calculated as MgO, 0.85 parts by weight of SrO, 1.98 parts by weight of Eu2O3, 0.19 parts by weight of GeO2, and 5.69 parts by weight of graphite were stirred in a mixer for 1.5 hours. Deionized water was added to it in an amount of 26.3% by weight relative to the total weight of the catalyst raw materials. The mixture was stirred for 0.5 hours. The resulting product was extruded into pellets with a diameter of 3 mm and a length of 6 mm. The pellets were placed in an oven, dried at 60 °C for 2 hours, and then dried at 130 °C for 3 hours, then placed in a muffle furnace, calcined at 650 °C for 3 hours, and then calcined at 920 °C for 3 hours to obtain a catalytic product thatIts composition is shown in Table 3. A catalyst was prepared, evaluated and analyzed as described in Example 1, the results of alkali content analysis and strength measurements are shown in Table 4 and the evaluation results are shown in Table 5. Comparative Example 14 48.56 parts by weight of red iron oxide, calculated as Fe2O3, 17.19 parts by weight of yellow iron oxide, calculated as Fe2O3, 6.8 parts by weight of potassium carbonate, calculated as K2O, 21.7 parts by weight of CeO2, 2.58 parts by weight of ammonium tungstate, calculated as WO3, 1.12 parts by weight of magnesium hydroxide, calculated as MgO, 4.84 parts by weight of ZnFe2O4, and 5.69 parts by weight of sodium carboxymethyl cellulose were stirred in a mixer for 1.5 hours, 26.3% by weight of the total weight of the catalyst raw materials was added to it in deionized water, mixed for 0.5 hours, the product was taken out and extruded into granules with a diameter of 3 mm and a length of 6 mm, the granules were placed in a furnace, at a temperature of They were dried at 60 °C for 2 h, and then dried at 130 °C for 3 h, then placed in a muffle furnace, and calcined at 650 °C for 3 h, and then calcined at 920 °C for 3 h to obtain the catalytic product whose composition is shown in Table 3. A catalyst was prepared, evaluated and analyzed as described in Example 1, the results of alkali content analysis and strength measurements are shown in Table 4 and the evaluation results are shown in Table 5. Table 1 Composition of catalysts obtained in examples and comparative examples Composition, weight percent Example 1 Comparative example 1 Comparative example 2 Example 2 Comparative example 3 Example 3 Comparative example 4 Example 4 Example 5 Example 6 Example 7 Example 8 Example 9 Fe2O3 75 / 3 79 / 13 77 / 4 75 / 3 77 / 4 75 / 3 75 / 3 75 / 3 75 / 3 75 / 3 75 / 3 70 / 91 66 / 07 K2O 4 / 66 4 / 9 4 / 66 4 / 66 4 / 66 4 / 66 4 / 66 4 / 66 4 / 66 4 / 66 2 / 37 4 / 66 CeO2 9 / 89 10 / 39 9 / 89 9 / 89 9 / 89 9 / 89 9 / 89 9 / 89 9 / 89 9 / 89 11 / 84 10 / 55 WO3 2 / 61 2 / 74 2 / 61 2 / 61 2 / 61 2 / 61 2 / 61 2 / 61 2 / 61 2 / 61 2 / 61 4 / 16 1 / 72 SrO 2 / 38 2 / 5 2 / 38 2 / 38 2 / 38 2 / 38 2 / 38 2 / 38 2 / 38 2 / 38 2 / 38 3 / 35 4 / 83 ZnFe2O4 3 / 16 0 0 3 / 16 0 3 / 16 0 3 / 16 3 / 16 3 / 16 3 / 16 5 / 5 7 / 65 ZnO 0 0 1 / 06 0 1 / 06 0 1 / 06 0 0 0 0 0 0 GeO2 1 / 68 0 1 / 68 0 0 0 0 0 / 84 0 / 84 0 0 / 56 0 / 85 4 / 4 SnO2 0 0 0 1 / 68 1 / 68 0 0 0 / 84 0 0 / 84 0 / 56 0 0 PbO2 0 0 0 0 0 1 / 68 1 / 68 0 0 / 84 0 / 84 0 / 56 0 0 HfO2 0 / 32 0 / 34 0 / 32 0 / 32 0 / 32 0 / 32 0 / 32 0 / 32 0 / 32 0 / 32 0 / 32 0 / 06 0 / 12 Sb2O5 0 0 0 0 0 0 0 0 0 0 0.96 0 Table 2 Composition of catalysts obtained in examples and comparative examples Composition, weight percent Example 10 Example 11 Comparative example 5 Comparative example 6 Comparative example 7 Comparative example 8 Example 12 Example 13 Example 14 Comparative example 9 Comparative example 10 Comparative example 11 Fe2O3 72 / 78 78 / 05 75 / 5 68 / 7 70 / 84 67 / 51 68 / 41 77 / 9 72 / 67 75 / 3 75 / 3 75 / 5 K2O 3 / 71 5 / 05 4 / 77 5 / 8 5 / 85 4 / 66 5 / 35 5 / 05 5 / 19 4 / 66 4 / 66 2 / 61 K2SiO3 0 0 4 / 55 0 0 0 0 0 0 0 0 K2ZnO2 0 0 0 0 0 0 0 0 0 0 0 4 / 55 CeO2 9 / 01 6 / 15 7 / 75 9 / 1 7 / 11 6 / 15 11 / 15 8 / 99 9 / 15 9 / 89 8 / 88 10 / 26 WO3 4 / 82 1 / 78 2 / 58 2 / 5 4 / 42 3 / 29 0 / 91 2 / 58 3 / 22 2 / 61 2 / 61 2 / 58 SrO 1 / 83 0 / 55 1 / 38 4 / 1 3 / 35 2 / 73 4 / 85 1 / 38 2 / 69 2 / 38 2 / 38 1 / 38 ZnFe2O4 2 / 82 6 / 15 3 / 74 4 / 9 3 / 5 8 / 28 4 / 65 0 / 95 0 3 / 16 3 / 16 3 / 74 NiFe2O4 0 0 0 0 0 0 0 0 2 / 65 0 0 0 GeO2 4 / 58 2 / 02 1 / 48 4 / 77 3 / 85 4 / 53 0 0 3 / 95 1 / 68 0 1 / 48 SnO2 0 0 0 0 0 0 4 / 4 0 0 0 1 / 68 0 PbO2 0 0 0 0 0 0 0 2 / 89 2 / 89 0 0 0 HfO2 0 / 45 0 / 25 0 / 02 0 / 13 0 / 09 0 / 75 0 / 28 0 / 26 0 / 48 0 / 32 0 0.02 Sb2O5 0 0 0 0 0 0 0 0 0 0 0 / 32 0 MoO3 0 0 0 0 0 / 99 0 0 0 0 0 0 0 Cement 0 0 0 0 0 2 / 1 0 0 0 0 0 0 MgO 0 0 0 0 0 0 0 0 0 0 1 / 01 0 Table 3 Composition of catalysts obtained in examples and comparative examples Composition, weight percent Comparative Example 12 Comparative Example 13 Comparative Example 14 Fe2O3 69 / 2 69 / 2 75 / 65 K2O 5 / 81 5 / 81 8 / 6 K2SiO3 5 / 73 0 0 K2ZnO3 0 5 / 73 0 CeO2 11 / 23 11 / 23 7 / 21 WO3 0 / 74 0 / 74 2 / 58 MgO 4 / 27 4 / 27 1 / 12 SrO 0 / 85 0 / 85 0 Eu2O3 1 / 98 1 / 98 0 GeO2 0 / 19 0 / 19 0 ZnFe2O4 0 0 4 / 84 Table 4 Changes in the properties of the catalysts obtained in the examples and comparative examples before and after the reaction Catalyst Before reaction After reaction Strong alkali content, mmol / g Total alkali content, mmol / g Strength, kg / mm ​​Strong alkali content, mmol / g Total alkali content, mmol / g Strength, kg / mm ​​Retention rate of strong alkali content, percent Retention rate of total alkali content, percent Strength retention rate, percent Example 1 0.066 0.371 3.35 0.057 0.334 2.88 86.36 90.03 85.97 Comparative example 1 0.044 0.237 1.55 0.022 0.121 0.76 50.0 51.05 49.03 Comparative example 2 0.052 0.286 1.76 0.029 0.160 0.96 55.77 55.94 54 / 55 Example 2 0 / 068 0 / 371 3 / 31 0 / 059 0 / 334 2 / 89 86 / 76 90 / 03 87 / 31 Comparative Example 3 0 / 055 0 / 306 1 / 82 0 / 031 0 / 177 1 / 04 56 / 36 57 / 84 57 / 14 Example 3 0 / 065 0 / 376 3 / 39 0 / 056 0 / 338 2 / 92 86 / 15 89 / 89 86 / 14 Comparative Example 4 0 / 056 0 / 313 1 / 89 0 / 032 0 / 185 1 / 1 57 / 14 59 / 11 58 / 2 Example 4 0 / 076 0 / 384 3 / 52 0 / 067 0 / 353 3 / 15 88 / 16 91 / 93 89 / 49 Example 5 0 / 072 0 / 382 3 / 61 0 / 064 0 / 348 3 / 22 88 / 89 91 / 1 89 / 20 Example 6 0 / 074 0 / 385 3 / 56 0 / 066 0 / 352 3 / 15 89 / 19 91 / 43 88 / 48 Example 7 0 / 079 0 / 397 3 / 88 0 / 073 0 / 377 3 / 6892 / 41 94 / 96 94.85 Example 8 0 / 067 0 / 366 3 / 38 0 / 058 0 / 330 2 / 94 86 / 57 90 / 16 86 / 98 Example 9 0 / 061 0 / 324 3 / 21 0 / 052 0 / 285 2 / 71 85 / 25 87 / 96 84 / 42 Example 10 0 / 064 0 / 339 3 / 18 0 / 055 0 / 306 2 / 76 85 / 94 90 / 27 86 / 79 Example 11 0 / 063 0 / 335 3 / 26 0 / 054 0 / 296 2 / 76 85 / 71 88 / 36 84 / 66 Comparative example 5 0 / 099 0 / 593 2 / 12 0 / 059 0 / 362 1 / 21 59 / 60 61 / 05 57 / 08 Comparative example 6 0 / 058 0 / 317 2 / 32 0 / 036 0 / 200 1 / 42 62 / 07 63 / 09 61 / 21 Comparative example 7 0 / 052 0 / 305 2 / 45 0 / 034 0 / 204 1 / 56 65 / 38 66 / 89 63 / 67 Comparative example 8 0 / 046 0 / 267 2 / 98 0 / 027 0 / 160 1 / 76 58 / 70 59 / 93 59 / 06 Example 12 0 / 068 0 / 36 3 / 41 0 / 059 0 / 324 2 / 98 86 / 76 90 / 0 87 / 39 Example 13 0 / 067 0 / 379 3 / 11 0 / 056 0 / 323 2 / 62 83 / 58 85 / 22 84 / 24 Example 14 0 / 062 0 / 337 3 / 12 0 / 053 0 / 303 2 / 66 85 / 48 89 / 91 85 / 27 Comparative Example 9 0 / 06 0 / 319 2 / 76 0 / 041 0 / 223 1 / 87 68 / 33 69 / 91 67 / 75 Comparative Example 10 0 / 094 0 / 587 2 / 45 0 / 058 0 / 370 1 / 46 61 / 70 63 / 03 59 / 59 Comparative Example 11 0 / 056 0 / 317 1 / 77 0 / 034 0 / 194 1 / 05 60 / 71 61 / 20 59 / 32 Comparative Example 12 0 / 083 0 / 473 2 / 32 0 / 052 0 / 305 1 / 47 62 / 65 64 / 48 63 / 36 ExampleComparative 13 0.091 0.517 2.16 0.055 0.321 1.33 60.44 62.09 61.57 Comparative Example 14 0.052 0.301 2.28 0.036 0.233 1.59 69.23 77.41 69.74 Table 5 Measured results of catalytic performance of catalysts obtained in examples and comparative examples Catalyst Reaction time 100 hours 1500 hours Benzene and toluene content in the product, wt% Ethylbenzene conversion, styrene selectivity, benzene and toluene content in the product, wt% Ethylbenzene conversion, styrene selectivity, Example 1 2.74 76.65 96.35 2.54 74.15 96.85 Comparative example 1 5.11 69.94 91.35 5.07 57.44 91.45 Comparative example 2 4.81 71.17 92.07 4.71 60.67 92.32 Example 2 2.86 76.5 96.21 2.65 73.9 96.73 Comparative example 3 4.66 71.1 92 / 31 4 / 55 61 / 3 92 / 59 Example 3 2 / 82 76 / 56 96 / 24 2 / 64 73 / 86 96 / 69 Comparative Example 4 4 / 75 71 / 21 92 / 15 4 / 65 61 / 36 92 / 39 Example 4 2 / 5 77 / 1 96 / 75 2 / 24 75 / 2 97 / 4 Example 5 2 / 57 77 / 2 96 / 67 2 / 29 75 / 25 97 / 37 Example 6 2 / 55 77 / 23 96 / 71 2 / 29 75 / 29 97 / 36 Example 7 2 / 26 77 / 6 97 / 17 1 / 93 76 / 7 97 / 99 Example 8 2 / 68 76 / 51 96 / 45 2 / 47 73 / 86 96 / 97 Example 9 3 / 45 75 / 18 94 / 76 3 / 27 68 / 68 95 / 15 Example 10 3 / 51 76 / 17 95 / 22 3 / 32 73 / 49 95 / 7 Example 11 3 / 2 76 / 24 95 / 65 3 / 01 73 / 66 96 / 13 Comparative Example 5 4 / 41 72 / 6 92 / 93 4 / 29 65 / 1 93 / 22 Comparative Example 6 4 / 17 73 / 2 93 / 54 4 / 05 64 / 4 93 / 85 Comparative Example 7 4 / 25 71 / 0 93 / 14 4 / 14 59 / 893 / 41 Comparative Example 8 4 / 61 71 / 37 92 / 52 4 / 54 60 / 47 92 / 7 Example 12 2 / 91 76 / 56 96 / 06 2 / 72 73 / 66 96 / 54 Example 13 3 / 59 75 / 67 95 / 04 3 / 41 72 / 37 95 / 5 Example 14 3 / 55 76 / 09 95 / 13 3 / 37 73 / 32 95 / 56 Comparative Example 9 3 / 85 71 / 8 93 / 92 3 / 69 65 / 30 94 / 31 Comparative Example 10 4 / 63 70 / 58 91 / 32 4 / 5 65 / 08 91 / 64 Comparative Example 11 4 / 43 72 / 58 92 / 9 4 / 3 65 / 28 93 / 22 Comparative example 12 3 / 57 71 / 93 93 / 56 3 / 43 68 / 02 93 / 89 Comparative example 13 3 / 71 71 / 07 93 / 39 3 / 59 66 / 23 93 / 65 Comparative example 14 4 / 16 72 / 11 92 / 54 4 / 01 67 / 89 92 / 93 As can be seen from the measured results of the above examples and comparative examples, compared with the catalysts of the comparative examples and prior art, the catalyst of the present application, by employing a specific coordination of elements and controlling the total alkali content in a range of 0.32 to 0.46 mmol / g and the strong alkali content in a range of 0.061 to 0.082 mmol / g, has outstanding advantages of high ethylbenzene conversion, less benzene and toluene by-products, high styrene selectivity, high stability in catalytic performance, and high strength and stability in alkali content before and after the reaction, which is beneficial to reducing the cost and improving the efficiency of the styrene plant. Therefore, the catalyst of the present application is a dehydrogenation catalyst that meets the market needs and can be well used in the industrial production of styrene by dehydrogenating ethylbenzene at a low reaction temperature and a very low steam-to-oil ratio. The present application has been illustrated in detail herein with reference to preferred embodiments, but is not intended to be limited to those embodiments. Various modifications may be made following the inventive concept of the present application, and such modifications should be within the scope of the present application. It should be noted that the various technical features described in the above examples may be combined in any suitable manner without contradiction, and in order to avoid unnecessary repetition, the various possible combinations are not described in the present application, but such combinations should also be within the scope of the present application. Furthermore, the various examples of the present disclosure may be combined arbitrarily so long as the combination does not depart from the spirit of the present disclosure, and such combined examples shall be considered as a disclosure of the present disclosure.

Claims

Claims 1. A cerium-potassium-iron based composite oxide catalyst, comprising, in addition to the metal elements Fe, K and Ce, a metal element M which is at least one selected from the group consisting of metal elements of Group IIA, metal elements of Group VIB other than Cr and metal elements of Group IVA, wherein the catalyst has a total alkali content of 0.32 to 0.46 mmol / g, preferably 0.32 to 0.42 mmol / g, more preferably 0.324 to 0.397 mmol / g, particularly preferably 0.384 to 0.397 mmol / g and a strong alkali content of 0.061 to 0.082 mmol / g, preferably 0.061 to 0.080 mmol / g, more preferably 0.061 to 0.079 mmol / g, particularly preferably 0.072 to 0.079 mmol / g It is.

2. The catalyst according to claim 1, wherein the metal element M is a combination of at least two elements selected from the group consisting of metal elements of Group IIA, metal elements of Group VIB other than metallic Cr, and metal elements of Group IVA, preferably a combination of at least one metal element of Group IIA, at least one metal element of Group VIB other than metallic Cr, and at least one metal element of Group IVA.

3. The catalyst according to claim 1 or 2, wherein the catalyst has at least one of the following characteristics: the Group IIA metal element present in the catalyst is not Mg, but is preferably Sr; the Group VIB metal element present in the catalyst is not Cr or Mo, but is preferably W; the Group IVA metal element present in the catalyst is selected from the group consisting of Ge, Sn and Pb or a combination thereof; and the catalyst does not include a binder such as montmorillonite, diatomite, cement, metahalosite, saponite, kaolin, halloysite, hydrotalcite, sepiolite, rectorite, attapulgite, bentonite, or a combination thereof.

4. The catalyst according to any one of claims 1 to 3, wherein the catalyst has at least one of the following characteristics: after 1500 hours of reaction under conditions including a pressure of -45 kPa, an ethylbenzene mass space velocity of 0.75 h-1, a temperature of 600°C and a weight ratio of water to ethylbenzene of 0.9, the crushing resistance retention rate of the catalyst is 80% or more; after 1500 hours of reaction under conditions including a pressure of -45 kPa, an ethylbenzene mass space velocity of 0.75 h-1, a temperature of 600°C and a weight ratio of water to ethylbenzene of 0.9, the total alkali content retention rate of the catalyst is 82% or more, and the strong alkali content retention rate of the catalyst is 80% or more; The catalyst has a reduction completion temperature of 730°C or higher based on the H2-TPR test.

5. Catalyst according to any one of claims 1 to 4, wherein the catalyst has a K2O content of from 2.3 to 6% by weight, preferably 2.3 to 5.5% by weight, based on the total amount of catalyst.

6. The catalyst according to claim 5, wherein the catalyst has a Fe2O3 content of 66 to 80 wt%, preferably 67.5 to 79 wt%; a K2O content of 2.3 to 6 wt%, preferably 2.3 to 5.5 wt%; a CeO2 content of 6 to 12 wt%; and a content of the oxide of the metal element M of 2 to 16 wt% based on the total amount of the catalyst; preferably, the catalyst has a WO3 content of 0.5 to 5 wt%, a SrO content of 0.5 to 5 wt%, and a Group IVA metal oxide content of 0.5 to 5 wt% based on the total amount of the catalyst.

7. The catalyst according to any one of claims 1 to 6, wherein the catalyst further comprises 0.5 to 8 wt%, preferably 1 to 7 wt%, more preferably 2 to 6 wt% of a ferrite, and the ferrite is preferably ZnFe2O4; preferably, the catalyst comprises 0.05 to 0.5 wt% of a Group IVB metal oxide, preferably HfO2, and / or 0.5 to 1.5 wt% of a Group VA metal oxide, preferably Sb2O5, based on the total amount of the catalyst.

8. A method for producing a cerium-potassium-iron-based oxide composite catalyst, according to any one of claims 1 to 7, comprising the steps of mixing a Fe source, a K source, a Ce source, an M source, optionally a source of a Group IVB metal element, optionally a source of a Group VA metal element, and optionally a ferrite, with a pore-forming agent and a solvent and shaping, optionally drying and / or calcining, to obtain the catalyst, wherein the M source is at least selected from a group consisting of sources of Group IIA metal elements, sources of Group VIB metal elements other than Cr, and sources of Group IVA metal elements, preferably at least one of a W source, a Sr source and a source of a Group IVA metal element, more preferably a combination of at least two W sources, a Sr source and a source of a Group IVA metal element, particularly preferably a combination of a W source, a Sr source and at least one source of a Group IVA metal element.

9. The method according to claim 8, comprising the steps of: 1) mixing the Fe source, the K source, the Ce source, the M source, the optional Group IVB metal element source and the optional Group VA metal element source with the pore forming agent; 2) mixing the mixture obtained in step 1) with ferrite; and 3) mixing the mixture obtained in step 2) with a solvent and shaping, optionally drying and / or calcining, to obtain the catalyst.

10. The method according to claim 8 or 9, wherein the method has at least one of the following features: the Fe source is selected from red iron oxide, yellow iron oxide or a combination thereof, preferably a combination of red iron oxide and yellow iron oxide, and preferably, the weight ratio of red iron oxide to yellow iron oxide calculated as Fe2O3 is 2 to 4:1; the Ce source is selected from cerium acetate, cerium hydroxide or a combination thereof; the K source is selected from potassium carbonate, potassium bicarbonate or a combination thereof; the Group IIA metal element source is selected from Group IIA metal element salts, Group IIA metal element oxides or a combination thereof, and preferably does not contain Mg; the Group VIB metal element source other than Cr is selected from Group VIB metal element salts, Group VIB metal element oxides or a combination thereof, and preferably does not contain Mo; The W source is selected from ammonium tungstate, ammonium metatungstate, tungsten trioxide or a combination thereof; the Sr source is selected from strontium carbonate, strontium hydroxide or a combination thereof; the Group IVA metal element source is selected from Group IVA metal element salts, metal element oxidesGroup IVA or a combination thereof, preferably the Group IVA metal element is selected from Ge, Sn and Pb or a combination thereof; the Group IVB metal element source is selected from Group IVB metal element salts, Group IVB metal element oxides or a combination thereof, preferably selected from salts containing Hf, HfO2 or a combination thereof; the Group VA metal element source is selected from Group VA metal element salts, Group VA metal element oxides or a combination thereof, preferably selected from salts containing Sb, Sb2O5 or a combination thereof; and the ferrite is ZnFe2O4.

11. The method according to any one of claims 8 to 10, wherein the method has at least one of the following features: the amount of added pore-forming agent is 2.2 to 3.6% by weight, preferably 3.8 to 6.5% by weight, based on the total amount of Fe source, K source, Ce source, M source, optional ferrite, optional Group IVB metal element source and optional Group VA metal element source; the pore-forming agent is selected from polystyrene, graphite, cellulose and derivatives thereof or a combination thereof; the amount of added solvent is 15 to 35% by weight, preferably 22 to 32% by weight, based on the total amount of catalyst raw materials; and the solvent is water.

12. The method according to any one of claims 8 to 11, wherein the method has at least one of the following features; the mixing time of step 1), step 2) and step 3) is independently 0.1 to 2 hours, preferably the mixing time of step 1) is 0.1 to 0.6 hours, the mixing time of step 2) is 1 to 2 hours, and the mixing time of step 3) is 0.2 to 1 hour; the drying conditions of step 3) include: a temperature of 30 to 145°C and a drying time of 1 to 8 hours, and preferably the drying includes drying at a temperature of 35 to 95°C for 0.5 to 4 hours, then heating to 95 to 145°C, and further drying for 0.5 to 4 hours; and the calcination conditions of step 3) are: a temperature of 320 to 960°C and a calcination time of 2 to 8 hours, preferably the calcination includes calcining at a temperature of 320 to 750°C for 1 to 4 hours, then heating to 750 to 960°C, and further calcining for 1 to 4 hours.

13. Use of a cerium-potassium-iron based composite oxide catalyst according to any one of claims 1 to 7 for the dehydrogenation of alkyl aromatic hydrocarbons, preferably alkyl aromatic hydrocarbons, one or more of 8C to 10C alkylbenzenes, more preferably ethylbenzene.

14. A process for the dehydrogenation of alkyl aromatics, comprising the step of contacting an alkyl aromatic hydrocarbon with a cerium-potassium-iron-based composite oxide catalyst according to any one of claims 1 to 7 for reaction under dehydrogenation conditions; preferably, the dehydrogenation conditions are: a temperature of 580 to 620°C, preferably 590 to 610°C, a mass space velocity of the alkyl aromatic hydrocarbon of 0.5 to 1h-1, preferably 0.6 to 0.8h-1, a weight ratio of water to alkyl aromatic hydrocarbon of 0.7 to 1, preferably 0.8 to 1, and a pressure of -60 kPa to atmospheric pressure, preferably -50 kPa to atmospheric pressure; Preferably, the alkyl aromatic hydrocarbon is one or more of the 8C to 10C alkylbenzenes, preferably ethylbenzene.

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