A dehydrogenation catalyst, a method for preparing the same, and a method for preparing an alkenyl arene

Abstract

The present application relates to a kind of dehydrogenation catalyst and its preparation method and application and a kind of preparation of alkenyl aromatic hydrocarbon method, the catalyst includes the following components by weight percentage: (a) 65~86% Fe2O3;(b) 6~12% alkali metal oxide;(c) 7~13% CeO2;(d) 0.5~4% alkali earth metal oxide;(e) 0.2~3% VIB group metal oxide;(f) 0.1~2% VB group metal oxide;(g) 0.05~1% heavy rare earth oxide;(h) 0.001-0.2% acidic oxide;(i) 0~4% binder.The catalyst of the present application has better catalytic activity in low water ratio conditions for preparing alkenyl aromatic hydrocarbon or olefin, and the selectivity of alkenyl aromatic hydrocarbon or olefin is high.

Description

TECHNICAL FIELD

[0001] The present application relates to a dehydrogenation catalyst, a preparation method and application thereof, and a method for preparing an alkenyl aromatic hydrocarbon. BACKGROUND

[0002] Alkenyl aromatic hydrocarbons are important organic monomers in the chemical industry, which can be used to synthesize plastics, rubbers and polyesters, etc. In industry, a typical production process is to prepare them by dehydrogenation of alkyl aromatic hydrocarbons. Taking styrene as an example, ethylbenzene dehydrogenation is widely used in industry, accounting for more than 85% of the styrene production capacity. Ethylbenzene dehydrogenation is a strong endothermic reversible reaction with an increase in the number of molecules. Superheated steam and ethylbenzene are reacted to produce styrene by feeding with a certain water / oil ratio and contacting with the catalyst, and the main by-product is benzene and toluene with low value. In industry, Fe-K-Ce catalysts are mainly used for direct catalytic dehydrogenation of ethylbenzene. Generally speaking, reducing the temperature, increasing the space velocity or introducing a small amount of CO2 into the raw material is beneficial to the selectivity of styrene. Under the same reaction conditions, the selectivity of the catalyst is mainly affected by diffusion, surface acidity and basicity, surface composition and structure. The ethylbenzene dehydrogenation reaction is an internal diffusion controlled reaction, and large pore size and low specific surface area are generally beneficial to the diffusion of reactants and products, thereby improving the selectivity of styrene. In addition, suitable acidity and basicity, active site electronic structure and coordination environment are also crucial to improving the selectivity of styrene.

[0003] Selectivity is an important indicator for evaluating industrial catalysts, and improving the selectivity of target products can reduce material consumption and separation energy consumption, improve raw material utilization and increase economic benefits. In the prior art, the selectivity of alkenyl aromatic hydrocarbons of alkyl aromatic hydrocarbon dehydrogenation catalysts is improved mainly by adjusting the structure of the additive, the type and content of the additive, the type of the pore forming agent or improving the preparation method, controlling the pore structure of the catalyst or modifying the Fe chemical environment.

[0004] Chinese patent ZL03150717.4 reports that the introduction of ppm-level noble metals Rh and Pd in the Fe-K-Ce-Mo system can improve the styrene yield and reduce the ratio of toluene / benzene.

[0005] Chinese patent ZL201210240057.X reports that the introduction of Ta2O5 and Group IVB metal oxides modifies the structure of the Fe-K-Ce-W-Mg catalyst system, which can reduce the toluene selectivity by 0.6% and increase the styrene selectivity by 0.5-1.0%.

[0006] CN202011099431.X discloses that a small amount of Ba, Li and Group VB metal oxides are introduced into the Fe-K-Ce-W-Mg system, and at the same time, the number of basic sites of the catalyst is controlled in the range of 0.387-0.455 mmol / g, thereby reducing the content of by-product benzene and significantly improving the selectivity of styrene.

[0007] Although the above techniques improve styrene selectivity to some extent by using different promoters or preparation methods, the water ratio conditions they are suitable for are relatively mild. SUMMARY

[0008] The present application is based on the problem of low water ratio catalyst selectivity and by-products in the prior art, and provides a low water ratio resistant dehydrogenation catalyst and a preparation method thereof. The catalyst has the characteristics of high selectivity while maintaining good catalytic activity under low water ratio conditions.

[0009] To achieve the above-mentioned purpose, the present application provides a dehydrogenation catalyst, which comprises the following components in percentage by weight: (a) 65-86% Fe2O3; (b) 6-12% alkali metal oxide; (c) 7-13% CeO2; (d) 0.5-4% alkaline earth metal oxide; (e) 0.2-3% VIB group metal oxide; (f) 0.1-2% VB group metal oxide; (g) 0.05-1% heavy rare earth oxide; (h) 0.001-0.2% acidic oxide; (i) 0-4% binder.

[0010] The second aspect of the present application provides a preparation method of the catalyst described in the present application, wherein the method comprises: mixing Fe source, alkali metal source, Ce source, alkaline earth metal source, VIB group metal source, VB group metal source, heavy rare earth metal source, solvent and optional binder source, and then performing optional drying and calcination after shaping; and then impregnating and contacting with an acidic oxide source, and optionally drying and calcining.

[0011] The third aspect of the present application provides a dehydrogenation catalyst for preparing alkenyl aromatic hydrocarbons or alkenes.

[0012] The fourth aspect of the present application provides a method for preparing alkenyl aromatic hydrocarbons, using alkyl aromatic hydrocarbons as raw materials, the reaction temperature is 580-650℃, the liquid space velocity is 0.2-1.5 hours -1 , the water / oil weight ratio is 0.7-3.0, the pressure is 10kPaA-atmospheric pressure, the raw materials are mixed with steam and contacted with the catalyst to occur dehydrogenation reaction.

[0013] The present application adds at least one VB group element oxide promoter and heavy rare earth oxide promoter in the Fe-alkali metal-Ce-VIB group-alkaline earth metal system, and preferably controls the mass ratio of VIB group and VB group metal oxides to be 0.5-20, thereby improving the selectivity of the catalyst to alkenyl aromatic hydrocarbons.

[0014] Furthermore, in the preferred embodiment, the optimized design of the preparation method promotes improved selectivity and yield of alkenyl aromatics in the catalyst. The catalyst prepared using this invention was evaluated in an isothermal fixed-bed reactor at atmospheric pressure, a reaction temperature of 620°C, and a liquid hourly space velocity of 1.0 h⁻¹. －1 When tested under a water ratio (by weight) of 1.05, the selectivity of alkenyl aromatics reached 96.0% or higher, achieving good technical results. Attached Figure Description

[0015] Figure 1 This is the NH3-TPD spectrum of the catalyst in Example 1 of the present invention. Detailed Implementation

[0016] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0017] The present invention provides a dehydrogenation catalyst comprising, by weight percentage: (a) 65-86% Fe₂O₃; (b) 6-12% alkali metal oxides; (c) 7-13% CeO₂; (d) 0.5-4% alkaline earth metal oxides; (e) 0.2-3% Group VIB metal oxides; (f) 0.1-2% Group VB metal oxides; (g) 0.05-1% heavy rare earth oxides; (h) 0.001-0.2% acidic oxides; and (i) 0-4% binder.

[0018] According to a preferred embodiment of the present invention, the ratio of strong acid sites to weak acid sites on the catalyst surface is (3.4-5.0):1, preferably (3.6-4.9):1, including but not limited to 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1, 4.2, 4.3, 4.5, 4.6, 4.7, 4.8, and 4.9. By employing the aforementioned preferred embodiment, it is possible to modify and control the adsorption properties of alkenyl aromatics and other products in the dehydrogenation process, such as the preparation of alkenyl aromatics from alkyl aromatics. While maintaining a certain level of activity, this reduces the formation of byproducts in the dehydrogenation reaction and improves the selectivity of alkenyl aromatics.

[0019] According to a preferred embodiment of the present invention, the mass ratio of group VIB metal oxide to group VB metal oxide is 0.5 to 20, preferably 1.0 to 12. By employing the aforementioned preferred embodiment, the acidity and basicity of the catalyst can be controlled, thereby improving the selectivity of alkenyl aromatics.

[0020] According to a preferred embodiment of the present application, the catalyst does not contain cobalt oxide and nickel oxide.

[0021] In the present application, the alkali metal elements are all applicable to the present application, according to a preferred embodiment of the present application, the alkali metal elements include but are not limited to at least one of Na, K, Rb. According to a preferred embodiment of the present application, the alkali metal oxide is selected from at least one of Na2O, K2O and Rb2O, preferably K2O; using the foregoing preferred embodiment, it can be achieved to maintain high catalytic activity under reaction conditions.

[0022] In the present application, the alkali earth metal elements are all applicable to the present application, according to a preferred embodiment of the present application, the alkali earth metal elements include but are not limited to at least one of Mg, Ca, Sr; according to a preferred embodiment of the present application, the alkali earth metal oxide is selected from at least one of MgO, CaO, SrO; using the foregoing preferred embodiment, it can be achieved to promote the formation of multi-alkali metal ferrite precursor.

[0023] In the present application, the VIB group elements are all applicable to the present application, according to a preferred embodiment of the present application, the VIB group elements include but are not limited to at least one of Cr, Mo, W; according to a preferred embodiment of the present application, the VIB group oxide contains at least one of Cr2O3, CrO3, MoO2, MoO3, WO2, WO3, preferably at least one of CrO3, MoO3, WO3; using the foregoing preferred embodiment, it can be achieved to achieve suitable crystal structure control and improve reduction resistance.

[0024] In the present application, preferably, the VIB group oxide content is 0.25-2.8%, including but not limited to 0.4%, 0.6%, 0.8%, 1.0%, 1.2%, 1.4%, 1.6%, 1.8%, 2.0%, 2.2%, 2.4%, 2.6% and the like.

[0025] In the present application, the VB group elements are all applicable to the present application, according to a preferred embodiment of the present application, the VB group elements include but are not limited to at least one of V, Nb, Ta; according to a preferred embodiment of the present application, the VB group metal oxide contains at least one of V2O3, V2O4, V2O5, V6O 13 , NbO2, Nb2O5, Ta2O5, preferably at least one of V6O 13 , V2O5, Nb2O5, Ta2O5; using the foregoing preferred embodiment, it can be achieved to regulate the electronic properties of alkali metal ferrite and reduce byproduct generation.

[0026] According to a preferred embodiment of the present application, the content of VB group metal oxide is 0.1-2%, preferably 0.2-1.9%, including but not limited to 0.4%, 0.6%, 0.8%, 1.0%, 1.2%, 1.4%, 1.6%, 1.8%, etc.

[0027] According to a preferred embodiment of the present application, the heavy rare earth element includes but is not limited to at least one of Y, Dy, Ho, Er, preferably at least two; according to a preferred embodiment of the present application, the heavy rare earth oxide is preferably selected from at least two of Y2O3, Dy2O3, Ho2O3 or Er2O3; using the aforementioned preferred embodiment, the growth of CeO2 crystals can be inhibited, and the stability of the catalyst under low water ratio conditions can be improved.

[0028] According to a preferred embodiment of the present application, the acidic oxide contains the oxide of one or more of Al, Si, P. According to a preferred embodiment of the present application, the acidic oxide contains at least one of the oxide of Al, Si, P; using the aforementioned preferred embodiment, in combination with the preparation method of preferably impregnating after shaping, the proportion of weak acid sites and strong acid sites on the surface of the catalyst can be regulated.

[0029] The catalysts with the aforementioned features of the present application can all achieve the purpose of the present application, and there is no special requirement for the preparation method thereof. For the present application, a preparation method of a catalyst is provided, wherein the method comprises: mixing a Fe source, an alkali metal source, a Ce source, an alkaline earth metal source, a VIB group metal source, a VB group metal source, a heavy rare earth metal source, a solvent, and an optional binder source, and then performing optional drying and calcination after shaping; and then performing impregnation contact with an acidic oxide source, and optionally drying and calcination.

[0030] According to a preferred embodiment of the present application, the method comprises the following steps:

[0031] (1) uniformly mixing a Fe source, an alkali metal source, a Ce source, an alkaline earth metal source, a VIB group metal source, a VB group metal source, a heavy rare earth metal source, a solvent, and an optional binder source to form a first mixed powder containing a solvent;

[0032] (2) kneading the first mixed powder after adding the solvent and removing part of the solvent to form a second mixed paste;

[0033] (3) shaping the second mixed paste by extrusion, pelletization, and drying, and then impregnating with an acidic oxide source.

[0034] In the present application, the method of mixing, kneading, and removing the solvent is not subject to special requirements, and the following exemplary descriptions are provided, but the scope of the present application is not limited thereto.

[0035] In this invention, step (1) can be performed, for example, by mixing evenly in a continuous agitator (belt mixer, plow mixer, etc.) or a batch high-speed mixer.

[0036] In this invention, step (2) can be performed by adding solvent to a kneader or a mixer for kneading.

[0037] In this invention, step (2) can, for example, remove part of the solvent by heating or negative pressure suction.

[0038] In this invention, there are no special requirements for the steps and methods of extruding, pelletizing and drying the second mixed paste in step (3), and conventional techniques can be used. This invention will not describe them in detail here.

[0039] In this invention, it is exemplarily described that the particles can be formed into cylindrical particles with a diameter of 3 mm and a length of 5 to 10 mm.

[0040] According to a preferred embodiment of the present invention, the method of the present invention includes:

[0041] (1) The Fe source, alkali metal source, Ce source, alkaline earth metal source, group VIB metal source, group VB metal source, heavy rare earth metal source, solvent and optional binder are mixed evenly in a continuous stirrer or mixer to form a first mixed powder containing a certain amount of solvent.

[0042] (2) Transfer the first mixed powder to a kneader or mixer, add solvent and knead; remove part of the solvent by heating or negative pressure suction to form a second mixed paste.

[0043] (3) After the second mixed paste is extruded, granulated and dried, it is impregnated with a weak acid, weak base or salt containing acidic metal to obtain the third mixed particles.

[0044] This invention does not have special requirements for the raw materials used; as long as the preparation is carried out in accordance with the steps described above, the purpose of this invention can be achieved.

[0045] In this invention, commonly used Fe sources can achieve the purpose of this invention. For this invention, preferred Fe sources include, but are not limited to, one or more of ferric nitrate, ferric oxide red, ferric oxide yellow, ferric oxide blue, ferric oxide green, ferric oxide gray, and ferric oxide black.

[0046] In this invention, commonly used alkali metal sources can achieve the purpose of this invention. For this invention, the alkali metal source includes, but is not limited to, at least one of alkali metal oxides, hydroxides, carbonates and nitrates.

[0047] In this invention, commonly used Ce sources can achieve the purpose of this invention. For this invention, the Ce source includes, but is not limited to, at least one of cerium oxide, carbonate, basic carbonate, oxalate, nitrate, sulfate, hydroxide, and ammonium salt.

[0048] In this invention, commonly used alkaline earth metal sources can achieve the purpose of this invention. For this invention, alkaline earth metal sources include, but are not limited to, at least one of alkaline earth metal oxides, hydroxides, carbonates, oxalates, and acetates.

[0049] In this invention, commonly used group VIB metal sources can achieve the purpose of this invention. For this invention, group VIB metal sources include, but are not limited to, at least one of group VIB metal oxides, nitrates, metal salts, and ammonium metal salts.

[0050] In this invention, commonly used group VB metal sources can achieve the purpose of this invention. For this invention, group VB metal sources include, but are not limited to, at least one of group VB metal oxides, hydroxides, ortho-acid salts, meta-acid salts, and ammonium salts.

[0051] In this invention, commonly used heavy rare earth metal sources can achieve the purpose of this invention. For this invention, the heavy rare earth metal source includes, but is not limited to, at least one of heavy rare earth oxides, nitrates, acetates, oxalates, and carbonates.

[0052] In this invention, in addition to the main catalyst component, a binder may be optionally added. Common binder sources can achieve the purpose of this invention. For this invention, the binder source includes, but is not limited to, at least one of the following: kaolin, diatomaceous earth, cement, silica sol, boehmite, potassium silicate, montmorillonite, halloysite, quasi-haloysite, soapstone, rettosite, sepiolite, attapulgite, hydrotalcite, bentonite, polyacrylamide, sodium polyacrylate, starch, cellulose ether, and povidone.

[0053] In this invention, a wide range of solvents can be selected. Specifically, the solvent is selected from one or more of water, alcohols, esters, ketones, ethers, and hydrocarbons; preferably, it is selected from one or more of water, methanol, ethanol, acetone, ethylene glycol, glycerol, and pyrrolidone, and more preferably includes at least two of these solvents. This can further improve the activity of the catalyst.

[0054] In this invention, the range of acidic oxide sources is relatively wide, generally selecting at least one of Al2O3, SiO2, and P2O5. For this invention, the preferred acidic oxide sources include one or more of a weak acid, weak base, and salt of an acidic metal.

[0055] In this invention, there are no special requirements for the total amount of solvent used. Commonly used solvent amounts can achieve the purpose of this invention. For this invention, the preferred total amount of solvent is 15-40% of the total mass of the catalyst as oxide, including but not limited to 18%, 21%, 24%, 27%, 30%, 33%, 36%, 39%, etc.

[0056] In this invention, the range of selectable operating conditions in step (1) is relatively wide. The following is an illustrative description, but it does not limit the scope of this invention. In this invention, the purpose of forming the first powder is to uniformly mix the raw material powder and the binder. For this invention, the solvent content of the first mixed powder is 1-10% by weight of the total mass of the catalyst as oxides, including but not limited to 2% by weight, 3% by weight, 4% by weight, 5% by weight, 6% by weight, 7% by weight, 8% by weight, 9% by weight, etc.

[0057] In this invention, the solvent in step (1) has a wide range of options, and all commonly used solvents can be used in this invention. For this invention, the solvent in step (1) preferably includes one or more of water, alcohols, esters, ketones, ethers, and hydrocarbons; preferably includes one or more of water, C1-C3 alcohols, and C1-C3 ketones; more preferably includes at least one of water, methanol, ethanol, and acetone; even more preferably includes water and ethanol, preferably the mass ratio of water to ethanol is 1-10:1, and more preferably 2-3:1.

[0058] In this invention, the range of selectable operating conditions in step (2) is relatively wide. The following is an illustrative description, but it does not limit the scope of this invention. For this invention, it is preferred that the solvent content used in the second mixture is 5-39% by weight of the total mass of the catalyst as oxides, including but not limited to 9% by weight, 13% by weight, 17% by weight, 21% by weight, 25% by weight, 29% by weight, 33% by weight, 37% by weight, etc.

[0059] In this invention, the solvent in step (2) has a wide range of options, and commonly used solvents can be used in this invention. For this invention, the solvent in step (2) preferably includes one or more of water, alcohols, esters, ketones, ethers, hydrocarbons, and amides; preferably includes one or more of water, C2-C3 diols and / or triols; preferably includes at least one of water, ethylene glycol, glycerol, and pyrrolidone, more preferably water and glycerol, preferably the mass ratio of water to glycerol is 0.1-10:1, more preferably the same amount of water and glycerol.

[0060] In this invention, the purpose of forming the second mixed paste is to convert the raw material powder into a non-Newtonian fluid with viscoelastic and thixotropic properties, which facilitates the subsequent catalyst molding. For this invention, the solid content of the second mixed paste is 65-100% by weight, preferably 80-95% by weight, including but not limited to 82% by weight, 84% by weight, 86% by weight, 88% by weight, 90% by weight, 92% by weight, and 94% by weight.

[0061] The aforementioned preferred embodiments can achieve uniform distribution of each component raw material in the catalyst, ensuring the impregnation effect of acidic oxides.

[0062] In this invention, there are no special requirements for the impregnation method in step (3). For this invention, it is preferred that the impregnation in step (3) be carried out by equal volume impregnation or excessive impregnation.

[0063] In this invention, there are no special requirements for the drying and calcination conditions. Specifically, for this invention, an exemplary description is given, for example, the drying temperature is 50-200℃, the drying time is 4-48 hours, the calcination temperature is 300-1300℃, and the calcination time is 3-18 hours.

[0064] According to a preferred embodiment of the present invention, the drying process involves two steps: the first drying temperature is 50-80°C; and the second drying temperature is 100-130°C. The drying times for the first and second drying steps can be selected within a wide range, for example, the first drying time is 10-15 hours, and the second drying time is 20-28 hours.

[0065] According to a preferred embodiment of the present invention, the roasting is carried out in two steps: the temperature of the first roasting is 300-500℃; and the temperature of the second roasting is 800-1000℃. The time for the first and second roasting can be selected within a wide range, for example, the first roasting time is 1-6 hours and the second roasting time is 2-8 hours.

[0066] According to a preferred embodiment of the present invention, the drying process involves two steps: the first drying is performed at a temperature of 50-80°C for 10-15 hours; the second drying is performed at a temperature of 100-130°C for 20-28 hours. This improves the performance of the catalyst.

[0067] According to a preferred embodiment of the present invention, the calcination is carried out in two steps: the first calcination is carried out at a temperature of 300-500°C for 1-6 hours; the second calcination is carried out at a temperature of 800-1000°C for 2-8 hours. This can improve the performance of the catalyst.

[0068] The dehydrogenation catalyst of the present invention has the advantages of high product selectivity and low by-products, and can be applied to various dehydrogenation reactions. The present invention provides the application of the dehydrogenation catalyst of the present invention in the preparation of alkenyl aromatics or olefins.

[0069] According to a preferred embodiment of the present invention, a method for preparing alkenyl aromatics is provided, using alkyl aromatics as raw materials, with a reaction temperature of 580–650°C and a liquid hourly space velocity of 0.2–1.5 h⁻¹. -1 The water / oil weight ratio is 0.7 to 3.0, the pressure is 10 kPaA to atmospheric pressure, and the raw materials are mixed with steam and come into contact with the catalyst to undergo a dehydrogenation reaction.

[0070] The catalyst of this invention overcomes the problems of poor selectivity and excessive by-products in existing low-water-ratio catalysts. While maintaining good catalytic activity under low-water-ratio conditions, it also has the characteristic of high selectivity for the target product.

[0071] The catalyst prepared by the method of this invention was evaluated for its performance in the ethylbenzene dehydrogenation reaction in an isothermal fixed bed. The process is briefly described below:

[0072] The reactor is a 1” stainless steel tube filled with 50–150 mL of cylindrical catalyst, 3 mm in diameter and 5–10 mm in length. Deionized water and ethylbenzene are separately metered into a preheating mixer, preheated and mixed into a gaseous state before entering the reactor. The reactor is heated by an electric heating wire to reach a predetermined temperature. The reaction temperature is 580–650 °C, and the liquid hourly space velocity (LHSV) is 0.2–1.5 h⁻¹. －1 The water ratio (water / ethylbenzene weight ratio) is 0.7–3.0 (preferably below 1.2, 1.05 in the example), and the pressure is 10 kPaA to atmospheric pressure. The reactants flowing out of the reactor are condensed in water and their composition is analyzed by gas chromatography.

[0073] Ethylbenzene conversion and styrene selectivity are calculated using the following formulas:

[0074]

[0075]

[0076]

[0077]

[0078] The solid content of the paste described in this invention is determined using a thermogravimetric analyzer. The specific steps are as follows: Take 10-20 mg of powder or block sample, heat it to 600 °C at a heating rate of 5 °C / min under N2 atmosphere, accurately weigh the thermal weight loss rate of the paste as the temperature rises within the corresponding solvent boiling point range, and the solid content can be calculated.

[0079] The acidic sites of the catalyst described in this invention were analyzed using the NH3-temperature programmed desorption (NH3-TPD) method with a TCD detector. 0.1-0.2 g of catalyst sample particles with a particle size of 40-60 mesh were pretreated at 550°C for 1 hour under a He atmosphere, then cooled to below 60°C. 10% NH3 / He was adsorbed until equilibrium was reached. He gas was then switched, and the baseline was established at 100°C. After leveling, the temperature was increased to 650°C at a rate of 10°C / min, and the NH3 desorption spectrum was recorded. The ratio of strong acid to weak acid sites was calculated based on the area ratio of the desorption peaks (strong acid sites) at temperatures above 400°C and below 400°C (weak acid sites).

[0080] In this invention, the catalyst composition is based on the composition calculated from the amount of feed.

[0081] Example 1

[0082] Iron oxide red, potassium hydroxide, cerium carbonate, ammonium molybdate, WO3, magnesium oxalate, CaO, ammonium metavanadate, niobium hydroxide, Y2O3, erbium nitrate, methylcellulose, and ethanol (equivalent to 5% by mass of the catalyst oxide) were stirred in a mixer for 2 hours until homogeneous. The mixture was then further stirred in a continuous mixer at 100 rpm to obtain a first mixed powder, which was transferred to a kneader.

[0083] A solvent water solution, equivalent to 20% of the catalyst by mass (based on oxides), was added dropwise to the mixer of a kneader at a uniform rate, and kneaded under a negative pressure of 50 kPa for 20 minutes. Analysis using a thermogravimetric analyzer revealed a paste with a solid content of 84.3%. The resulting paste was extruded and granulated to obtain particles with a diameter of 3 mm and a length of 5-10 mm. Subsequently, an equal volume of silicic acid solution, equivalent to 0.01 parts of SiO2, was impregnated onto the particles, and the mixture was allowed to stand for 4 hours. The particles were then placed in an oven and dried at 70°C for 12 hours, then at 120°C for 24 hours. Finally, the mixture was calcined in a muffle furnace at 450°C for 4 hours and then at 900°C for 4 hours to obtain the finished catalyst. The catalyst composition is listed in Table 1.

[0084] Figure 1 The image shows the NH3-TPD spectrum of catalyst Example 1. The ratio of strong acid sites to weak acid sites in the catalyst was determined to be 4.30 by NH3-TPD.

[0085] 100 ml of catalyst was loaded into the reactor and incubated at atmospheric pressure and a liquid hourly space velocity (LHSV) of 1.0 h⁻¹. －1 The performance was evaluated at a temperature of 620℃ and a water ratio of 1.05 (wt), and the test results are listed in Table 2.

[0086] Example 2

[0087] Iron oxide yellow, potassium carbonate, basic cerium carbonate, sodium nitrate, MoO3, chromium nitrate, magnesium hydroxide, SrO, and V6O are added. 13 Dysprosium nitrate, Ho₂O₃, methylcellulose, and methanol (equivalent to 2% by mass of the catalyst oxide) were stirred in a mixer for 0.5 hours until homogeneous. The mixture was then further stirred in a continuous mixer at 80 rpm to obtain a first mixed powder, which was transferred to a grinding mill.

[0088] A solvent water equivalent to 14% of the catalyst by mass (based on oxides) was uniformly added dropwise to a mixer, and the mixture was wet-kneaded under a negative pressure of 20 kPaA for 120 min. Thermogravimetric analysis of the sample revealed a solid content of 94.6% in the obtained paste. The paste was then extruded and granulated to obtain particles with a diameter of 3 mm and a length of 5-10 mm. Subsequently, an equal volume of aluminic acid (equivalent to 0.11 parts Al₂O₃) and phosphoric acid solution (0.07 parts) was impregnated onto the particles, and the mixture was allowed to stand for 4 h. The particles were then placed in an oven and dried at 60℃ for 12 h, then at 100℃ for 24 h, and finally calcined in a rotary kiln at 350℃ for 4 h and 850℃ for 4 h to obtain the finished catalyst. The catalyst composition is listed in Table 1. The ratio of strong acid sites to weak acid sites in the catalyst, determined by NH₃-TPD, was 4.75.

[0089] The catalyst was tested and evaluated according to the method in Example 1, and the test results are listed in Table 2.

[0090] Example 3

[0091] Iron oxide red, potassium nitrate, cerium nitrate, ammonium tungstate, magnesium carbonate, Nb₂O₅, yttrium nitrate, dysprosium nitrate, Ho₂O₃, Er₂O₃, methylcellulose, and water (equivalent to 10% by mass of the catalyst oxide) were stirred in a mixer for 1 hour until homogeneous. The mixture was then further stirred at 70 rpm in a continuous mixer to obtain a first mixed powder, which was transferred to a kneader.

[0092] A water-ethylene glycol (1:1) mixture, equivalent to 30% of the catalyst by mass (based on oxides), was uniformly dripped into a kneader and kneaded under negative pressure at 80 kPa for 10 minutes. Thermogravimetric analysis revealed a paste with a solid content of 80.50%. The paste was then extruded and granulated to obtain particles with a diameter of 3 mm and a length of 5-10 mm. Subsequently, an equal volume of aluminic acid solution (equivalent to 0.002 parts Al₂O₃) was impregnated onto the particles, and the mixture was allowed to stand for 4 hours. The particles were then placed in an oven and dried at 50°C for 12 hours, then at 110°C for 24 hours, and finally calcined in a muffle furnace at 400°C for 4 hours and 820°C for 4 hours to obtain the finished catalyst. The catalyst composition is listed in Table 1. The ratio of strong acid sites to weak acid sites in the catalyst, determined by NH₃-TPD, was 3.65.

[0093] The catalyst was tested and evaluated according to the method in Example 1, and the test results are listed in Table 2.

[0094] Example 4

[0095] Compared with Example 1, “5% solvent ethanol” was replaced with “5% water + ethanol (water to ethanol mass ratio 2:1)”, and “20% solvent water” was replaced with “20% water + glycerol (water to glycerol mass ratio 1:1)”. Other steps were the same as in Example 1, and the catalyst composition is listed in Table 1.

[0096] The ratio of strong acid sites to weak acid sites in the catalyst was determined to be 4.16 by NH3-TPD.

[0097] The catalyst was tested and evaluated according to the method in Example 1, and the test results are listed in Table 2.

[0098] Example 5

[0099] Compared to Example 1, the proportions of some raw materials were changed. Other steps were the same as in Example 1, and the catalyst composition is listed in Table 1.

[0100] The ratio of strong acid sites to weak acid sites in the catalyst was determined to be 4.83 by NH3-TPD.

[0101] The catalyst was tested and evaluated according to the method in Example 1, and the test results are listed in Table 2.

[0102] Example 6

[0103] The difference from Example 1 is the addition of nickel oxide. All other steps are the same as in Example 1, and the catalyst composition is listed in Table 1.

[0104] The ratio of strong acid sites to weak acid sites in the catalyst was determined to be 4.05 by NH3-TPD.

[0105] The catalyst was tested and evaluated according to the method in Example 1, and the test results are listed in Table 2.

[0106] Example 7

[0107] Compared to Example 1, the mass ratio of oxides of the same group elements was kept constant, while the mass ratio of group VIB and group VB elements and the content of acidic oxides were adjusted. Other steps were the same as in Example 1, and the catalyst composition is listed in Table 1.

[0108] The ratio of strong acid sites to weak acid sites in the catalyst was determined to be 3.47 by NH3-TPD.

[0109] The catalyst was tested and evaluated according to the method in Example 1, and the test results are listed in Table 2.

[0110] Example 8

[0111] Compared to Example 3, the raw materials and conditions were changed, with the addition of iron oxide yellow, potassium hydroxide, cerium nitrate, ammonium metatungstate, calcium hydroxide, and V6O. 13 Niobium oxalate, Ho2O3, erbium nitrate, methylcellulose, and water (equivalent to 10% of the catalyst mass) are mixed evenly in a mixer.

[0112] A water + ethylene glycol (1:1) mixed solvent, equivalent to 30% of the catalyst mass, was added dropwise to a kneader and kneaded at normal pressure for 30 minutes. Other steps were the same as in Example 3, and the catalyst composition is listed in Table 1.

[0113] Thermogravimetric analysis revealed that the solid content of the second mixed paste was 69.7%. NH3-TPD analysis showed that the ratio of strong acid sites to weak acid sites in the catalyst was 3.91.

[0114] The catalyst was tested and evaluated according to the method in Example 1, and the test results are listed in Table 2.

[0115] Comparative Example 1

[0116] Compared with Example 1, this example does not contain group VB metal oxide additives, but the other steps are the same as in Example 1. The catalyst composition is listed in Table 1.

[0117] The ratio of strong acid sites to weak acid sites in the catalyst was determined to be 7.58 by NH3-TPD.

[0118] The catalyst was tested and evaluated according to the method in Example 1, and the test results are listed in Table 2.

[0119] Comparative Example 2

[0120] Compared with Example 2, there was no acidic oxide impregnation treatment, and the other steps were the same as in Example 2. The catalyst composition is listed in Table 1.

[0121] The ratio of strong acid sites to weak acid sites in the catalyst was determined to be 15.1 by NH3-TPD.

[0122] The catalyst was tested and evaluated according to the method in Example 1, and the test results are listed in Table 2.

[0123] Table 1

[0124]

[0125]

[0126] Table 2

[0127]

[0128] Note: The evaluation conditions for the above embodiments used an airspeed of 1.0 h. -1 Water ratio (wt) 1.05.

[0129] The above examples and comparative examples illustrate that by adding a certain proportion of at least one group VB metal (V, Nb, Ta) oxide promoter and a heavy rare earth metal (Y, Dy, Ho, Er) oxide promoter to the iron-alkali metal-cerium-VIB group-alkaline earth metal system, and in the preferred embodiment, introducing a trace amount of acidic oxide on the catalyst surface to control the mass ratio of group VIB and group VB metal oxides in the catalyst, the catalyst exhibits high selectivity for alkenyl aromatics under low water ratio conditions, making it suitable for industrial production of alkenyl aromatics from alkyl aromatics under low water ratio conditions.

[0130] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A dehydrogenation catalyst, characterized in that, The catalyst comprises, by weight percentage, the following components: (a) 65–86% Fe₂O₃; (b) 6–12% alkali metal oxides; (c) 7–13% CeO₂; (d) 0.5–4% alkaline earth metal oxides; (e) 0.2–3% Group VIB metal oxides; (f) 0.1–2% Group VB metal oxides; (g) 0.05–1% heavy rare earth oxides; (h) 0.001–0.2% acidic oxides; and (i) 0–4% binder, wherein the ratio of strong acid sites to weak acid sites on the catalyst surface is (3.4–5.0):1, and the acidic oxides comprise one or more oxides of Al, Si, and P.

2. The catalyst according to claim 1, wherein, The ratio of strong acid sites to weak acid sites on the catalyst surface is (3.6-4.9):1; and / or The mass ratio of group VIB metal oxides to group VB metal oxides is 0.5–20; and / or The catalyst does not contain cobalt oxide or nickel oxide.

3. The catalyst according to claim 2, wherein, The mass ratio of group VIB metal oxides to group VB metal oxides is 1.0 to 12.

4. The catalyst according to claim 1, wherein, Alkali metal elements include at least one of Na, K, and Rb; and / or Alkaline earth metal elements include at least one of Mg, Ca, and Sr; and / or Group VIB elements include at least one of Cr, Mo, and W; and / or VB family elements include at least one of V, Nb, and Ta; and / or Heavy rare earth elements include at least one of Y, Dy, Ho, and Er.

5. The catalyst according to claim 4, wherein, Heavy rare earth elements include at least two of Y, Dy, Ho, and Er.

6. A method for preparing the catalyst according to any one of claims 1-5, wherein, The method includes: mixing an Fe source, an alkali metal source, a Ce source, an alkaline earth metal source, a group VIB metal source, a group VB metal source, a heavy rare earth metal source, a solvent, and an optional binder source, molding the mixture, and then optionally drying and calcining it; subsequently impregnating and contacting it with an acidic oxide source, and optionally drying and calcining it.

7. The preparation method according to claim 6, wherein the mixing comprises the following steps: (1) Mix the Fe source, alkali metal source, Ce source, alkaline earth metal source, group VIB metal source, group VB metal source, heavy rare earth metal source, solvent, and optionally binder source evenly to form a first mixed powder containing solvent. (2) After adding the first mixed powder to the solvent, knead it and remove part of the solvent to form the second mixed paste; (3) After the second mixed paste is extruded, granulated and dried, it is impregnated with an acidic oxide source.

8. The preparation method according to claim 6, wherein, The Fe source includes one or more of ferric nitrate, ferric oxide red, ferric oxide yellow, ferric oxide blue, ferric oxide green, ferric oxide gray, and ferric oxide black; and / or Alkali metal sources include at least one of alkali metal oxides, hydroxides, carbonates, and nitrates; and / or Ce sources include at least one of cerium oxide, carbonate, basic carbonate, oxalate, nitrate, sulfate, hydroxide, and ammonium salt; and / or Alkaline earth metal sources include at least one of the following: oxides, hydroxides, carbonates, oxalates, and acetates of alkaline earth metals; and / or Group VIB metal sources include at least one of group VIB metal oxides, nitrates, metal salts, and ammonium metal salts; and / or Group VB metal sources include at least one of the following: oxides, hydroxides, orthoates, metaates, and ammonium salts of Group VB metals; and / or Heavy rare earth metal sources include at least one of heavy rare earth oxides, nitrates, acetates, oxalates, and carbonates; and / or The binder source includes at least one of the following: kaolin, diatomaceous earth, cement, silica sol, boehmite, potassium silicate, montmorillonite, halloysite, pseudo-haloysite, soapstone, palygorskite, sepiolite, attapulgite, hydrotalcite, bentonite, polyacrylamide, sodium polyacrylate, starch, methylcellulose, cellulose ether, and povidone; and / or The solvent is selected from one or more of water, alcohols, esters, ketones, ethers, and hydrocarbons; and / or Acidic oxide sources include one or more of the following: weak acids, weak bases, and salts of acidic metals; and / or The total amount of solvent is 15-40% of the total mass of the catalyst as oxides.

9. The preparation method according to claim 8, wherein, Solvents include one or more of water, methanol, ethanol, acetone, ethylene glycol, glycerol, and pyrrolidone.

10. The preparation method according to claim 9, wherein, The solvent includes at least two of the following: water, methanol, ethanol, acetone, ethylene glycol, glycerol, and pyrrolidone.

11. The preparation method according to claim 7, wherein, In step (1), The solvent content of the first mixed powder is 1-10% by weight of the total mass of the catalyst (calculated as oxides). The solvent includes one or more of water, alcohols, esters, ketones, ethers, and hydrocarbons; and / or In step (2), The solvent content used in the second mixture is 5-39% by weight of the total mass of the catalyst as oxides; and / or The solvent includes one or more of water, alcohols, esters, ketones, ethers, hydrocarbons, and amides; and / or The solid content of the second mixed paste is 65-100% by weight. and / or In step (3), the impregnation is carried out by either equal volume impregnation or excessive volume impregnation.

12. The preparation method according to claim 11, wherein, In step (1), The solvent includes at least one of water, methanol, ethanol, and acetone; and / or In step (2), The solvent includes at least one of water, ethylene glycol, glycerol, and pyrrolidone; and / or The solid content of the second mixed paste is 80-95% by weight.

13. The preparation method according to claim 12, wherein, In step (1), The solvent is water and ethanol; and / or In step (2), The solvent is water and glycerol.

14. The preparation method according to claim 6, wherein, The drying temperature is 50-200℃, and the calcination temperature is 300-1300℃.

15. The preparation method according to claim 14, wherein, The drying process involves two steps: the first drying temperature is 50-80℃; the second drying temperature is 100-130℃; and / or The roasting process involves two steps: the first roasting temperature is 300-500℃, and the second roasting temperature is 800-1000℃.

16. The preparation method according to claim 15, wherein, The drying process involves two steps: the first drying step is performed at 50-80℃ for 10-15 hours; the second drying step is performed at 100-130℃ for 20-28 hours; and / or The roasting process involves two steps: the first roasting is carried out at a temperature of 300-500℃ for 1-6 hours; the second roasting is carried out at a temperature of 800-1000℃ for 2-8 hours.

17. The use of any one of the dehydrogenation catalysts of claims 1-5 in the preparation of alkenyl aromatics or olefins.

18. A method for preparing alkenyl aromatics, using alkyl aromatics as raw materials, with a reaction temperature of 580–650 °C and a liquid hourly space velocity of 0.2–1.5 h⁻¹. -1 The water / oil weight ratio is 0.7 to 3.0, the pressure is 10 kPaA to atmospheric pressure, and the raw materials are mixed with steam and contacted with any one of the dehydrogenation catalysts in claims 1-5 to undergo a dehydrogenation reaction.

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