阅读说明：本技术 烷基芳烃脱氢的方法 (Process for dehydrogenating alkylaromatic hydrocarbons ) 是由 危春玲 缪长喜 陈铜 刘岳峰 冯璐 于 2019-10-14 设计创作，主要内容包括：本发明涉及脱氢技术领域,公开了一种烷基芳烃脱氢的方法,该方法包括：在无水条件下,(1)将含有烷基芳烃的原料与碳基催化剂进行第一接触,生成物流W；(2)将所述物流W与铁钾铈系催化剂进行第二接触,得到烷烯基芳烃。本发明提供的方法具有成本低,适合长周期运行的优势,且烷基芳烃转化率和产品选择性保持较高。(The invention relates to the technical field of dehydrogenation, and discloses a method for dehydrogenating alkyl aromatic hydrocarbon, which comprises the following steps: under anhydrous condition, (1) carrying out first contact on a raw material containing alkyl aromatic hydrocarbon and a carbon-based catalyst to generate a material flow W; (2) and carrying out second contact on the material flow W and a ferrum-potassium-cerium catalyst to obtain the alkyl alkenyl arene. The method provided by the invention has the advantages of low cost and suitability for long-period operation, and the conversion rate of alkyl aromatics and the selectivity of products are kept high.)

1. A process for the dehydrogenation of an alkylaromatic hydrocarbon, the process comprising: under the condition of no water, the water-soluble organic solvent is used,

(1) carrying out first contact on a raw material containing alkyl aromatic hydrocarbon and a carbon-based catalyst to generate a material flow W;

(2) and carrying out second contact on the material flow W and a ferrum-potassium-cerium catalyst to obtain the alkyl alkenyl arene.

2. The method of claim 1, wherein the carbon-based catalyst and the iron potassium cerium-based catalyst are respectively filled in two fixed bed reactors connected in series, or the carbon-based catalyst and the iron potassium cerium-based catalyst are filled in different beds of one fixed bed reactor, and the carbon-based catalyst is positioned at the upstream of the iron potassium cerium-based catalyst along the material flow direction;

preferably, the loading ratio of the carbon-based catalyst to the iron-potassium-cerium-based catalyst is 1: (0.1-1).

3. The process according to claim 1, wherein the alkylaromatic hydrocarbon is selected from at least one of ethylbenzene, methylethylbenzene and diethylbenzene, preferably ethylbenzene;

preferably, the alkylaromatic-containing feedstock comprises an alkylaromatic, a diluent, and an oxidant;

preferably, the oxidant is an oxygen-containing gas, further preferably, the oxygen content in the oxidant is above 10 vol%, preferably above 20 vol%, further preferably air and/or oxygen, more preferably oxygen;

preferably, the diluent is selected from at least one of inert gases;

preferably, the volume concentration of the alkyl aromatic hydrocarbon in the raw material is 0.5-15%, and the molar ratio of the alkyl aromatic hydrocarbon to the oxidant calculated by oxygen is 1: (0.1-2).

4. The process according to any one of claims 1 to 3, wherein the carbon-based catalyst comprises a support and an active component supported on the support;

preferably, the support is silicon carbide, preferably beta-SiC;

preferably, the active component is at least one of nanodiamond, nanocellulose and carbon nanotubes, further preferably nanodiamond;

further preferably, the active component includes nanodiamond and a modifying element selected from at least one of nitrogen, phosphorus, and boron.

5. The method according to claim 4, wherein the content of modifying elements in the active component is 1-45 wt%, preferably 20-38 wt%;

preferably, the modifying element is nitrogen element and/or phosphorus element, preferably nitrogen element and phosphorus element, and further preferably, the mass ratio of nitrogen element to phosphorus element is (1-40): 1, preferably (3-33): 1;

preferably, the content of the active component is 20-60 wt%, preferably 35-50 wt%, based on the total amount of the carbon-based catalyst; the content of the carrier is 40-80 wt%, preferably 50-65 wt%;

preferably, the carbon-based catalyst has a specific surface area of 70 to 250m²/g；

Preferably, the particle size of the active component is 1-10 nm.

6. The method of claim 4 or 5, wherein the carbon-based catalyst is prepared by a method comprising:

(a-1) mixing the nanodiamond, glucose, a dispersing agent, a solvent and an optional compound containing a modification element to obtain an active component suspension;

(a-2) immersing a carrier in the active component suspension of the step (a-1), and then sequentially drying, pre-calcining and calcining;

the modifying element-containing compound is selected from at least one of a nitrogen source, a boron source, and a phosphorus source.

7. The method of claim 6, wherein the glucose to nanodiamond mass ratio is 0.5-1.5: 1, preferably 0.8 to 1.2: 1;

preferably, the dispersant is selected from at least one of citric acid, ammonium citrate and polyethylene glycol, preferably citric acid;

preferably, the mass ratio of the dispersing agent to the nanodiamond is 0.5-2: 1, preferably 1 to 1.5: 1.

8. the method of claim 6, wherein,

the nitrogen source is selected from at least one of ammonium carbonate, ammonium sulfate, urea and ammonia water, and ammonium carbonate is preferred;

the boron source is selected from boric acid and/or sodium tetraborate, preferably boric acid;

the phosphorus source is selected from at least one of ammonium dihydrogen phosphate, diammonium hydrogen phosphate and ammonium phosphate, and is preferably ammonium dihydrogen phosphate;

the solvent is water and/or an organic solvent;

preferably, the mixing in step (1) is carried out under ultrasonic conditions for 10-200min, preferably 10-100 min.

9. The method of claim 6, wherein,

the drying conditions in the step (2) comprise: the temperature is 100-150 ℃, and the time is 5-12 hours;

preferably, the pre-calcining conditions of step (2) include: under the oxygen-containing atmosphere, the temperature is 350-550 ℃, and preferably 400-500 ℃; the time is 1 to 8 hours, preferably 2 to 6 hours; preferably, the oxygen-containing atmosphere is air;

preferably, the calcining conditions of step (2) include: under the inert atmosphere, the temperature is 600-900 ℃, and preferably 600-800 ℃; the time is 1 to 12 hours, preferably 2 to 8 hours; preferably, the inert atmosphere is neon and/or argon.

10. The method of any of claims 1-9, wherein the iron potassium cerium-based catalyst comprises: fe₂O₃、K₂O、CeO₂、MoO₃And CaO; preferably, Fe is contained in the total amount of the ferroceranium-based catalyst₂O₃In an amount of 65-76 wt.%, K₂O content of 6-14 wt%, CeO₂In an amount of 14 to 20% by weight,MoO₃the content of (B) is 0.5-5 wt%, and the content of CaO is 0.2-5 wt%.

11. The method of claim 10, wherein the preparation of the ferrocenium cerium-based catalyst comprises:

(b-1) dry-mixing a first portion of a cerium source, an iron source, a potassium source, a molybdenum source, a calcium source, and a pore-forming agent to obtain a catalyst precursor Q;

(b-2) mixing a second part of the cerium source, a solvent and the catalyst precursor Q, and extruding, molding and roasting the obtained mixture;

preferably, as CeO₂The first part of cerium source accounts for 70-95 wt% of the total amount of cerium source.

12. The method of any one of claims 1-11,

the conditions of the first and second contacting each independently comprise: the reaction temperature is 400-;

preferably, the conditions of the first contacting and the second contacting each independently comprise: the reaction temperature is 450-550 ℃, and the space velocity of the raw material containing the alkyl aromatic hydrocarbon is 7000-13000 mL/g.h.

Technical Field

The invention relates to the technical field of dehydrogenation, in particular to a method for dehydrogenating alkyl aromatic hydrocarbon.

Background

Industrial production of alkyl alkenyl aromatic hydrocarbons is mainly obtained by dehydrogenation of alkyl aromatic hydrocarbons, for example, industrial production of styrene is mainly catalytic dehydrogenation of ethylbenzene, the production capacity of which is about 85% of the total production capacity of styrene; the industrial production method of the divinylbenzene is mainly obtained by catalytic dehydrogenation of diethylbenzene. The dehydrogenation reaction of alkyl aromatic hydrocarbon is a strong endothermic reaction with increased molecular number, and the generation of target products is facilitated by high temperature and low pressure. Usually, the production process adopts the process conditions of adding a large amount of superheated steam at high temperature and negative pressure. Therefore, a large amount of water vapor is consumed in the production process, and the high energy consumption is a prominent problem in the production process.

Compared with direct catalytic dehydrogenation, the oxidative dehydrogenation reaction is not limited by equilibrium conversion rate, and the exothermic reaction at lower temperature is used to replace the endothermic reaction at high temperature, thus greatly reducing energy consumption and improving efficiency. However, the oxidative dehydrogenation reaction of alkyl aromatic hydrocarbon is easy to generate deep oxidation, and corresponding by-products such as ketones, aldehydes and the like are generated, so that the number of the by-products is large, and the selectivity is low, so that how to improve the selectivity of the alkyl aromatic hydrocarbon becomes one of the key directions of research.

The dehydrogenation reaction of alkyl aromatic hydrocarbon has more catalytic systems, which can be divided into a composite metal oxide catalyst system, a heteroatom molecular sieve system, a carbonaceous catalyst, a carbon molecular sieve system and the like. The dehydrogenation catalyst commonly used at present is Fe-K-Ce-Mo series, and after being roasted at high temperature, the catalyst generally contains alpha-Fe₂O₃And an iron potassium compound phase. However, in the conventional dehydrogenation process, due to the existence of a large amount of water vapor, the catalyst is continuously washed during long-term operation, which easily causes the strength of the catalyst to be reduced, and the service life of the catalyst is affected.

At present, the research on new processes for dehydrogenation of alkyl aromatic hydrocarbons is receiving more and more attention. There is a need to develop a new process with low production cost, long catalyst life and high product selectivity.

If the characteristics of various different catalyst systems can be combined, the catalysts are combined and optimized in process, so that the effects of reducing the cost of a production device and prolonging the service life of the catalysts are achieved, and the benefits of the industry are greatly improved.

Disclosure of Invention

The invention aims to overcome the technical problems of high energy consumption and low conversion rate of alkyl aromatics during long-period operation in the process of producing the alkyl alkenyl aromatics by dehydrogenating the alkyl aromatics in the prior art, and provides a method for dehydrogenating the alkyl aromatics, which has the characteristic of low cost and is suitable for long-period operation, and in addition, the conversion rate of the alkyl aromatics and the product selectivity are kept at a higher level.

The inventor of the invention finds in research that the secondary continuous reaction of the alkyl aromatic hydrocarbon by adopting the method for dehydrogenating the alkyl aromatic hydrocarbon provided by the invention can effectively combine the advantages of two different catalysts, on one hand, the method can reduce energy consumption, on the other hand, the method is favorable for avoiding the pressure drop of a fixed bed reactor, is very suitable for a long-period production process, and keeps the conversion rate of the alkyl aromatic hydrocarbon and the selectivity of products to be higher continuously.

In order to achieve the above object, the present invention provides a method for dehydrogenating an alkylaromatic hydrocarbon, the method comprising: under the condition of no water, the water-soluble organic solvent is used,

(1) carrying out first contact on a raw material containing alkyl aromatic hydrocarbon and a carbon-based catalyst to generate a material flow W;

(2) and carrying out second contact on the material flow W and a ferrum-potassium-cerium catalyst to obtain the alkyl alkenyl arene.

Preferably, the carbon-based catalyst and the iron potassium cerium catalyst are respectively filled in two fixed bed reactors connected in series, or the carbon-based catalyst and the iron potassium cerium catalyst are filled in different beds of one fixed bed reactor, and the carbon-based catalyst is positioned at the upstream of the iron potassium cerium catalyst along the material flow direction.

Preferably, the loading ratio of the carbon-based catalyst to the iron-potassium-cerium-based catalyst is 1: (0.1-1).

In the invention, alkyl arene reacts with a double-catalyst system, the upstream catalyst is a carbon-based catalyst, and the downstream catalyst is a ferrum-potassium-cerium-based catalyst, so that the method for preparing the alkyl alkenyl arene is suitable for long-period operation, and after the operation is carried out for 100 hours, the conversion rate of the alkyl arene can reach more than 34%; after running for 50 hours, the product selectivity can reach more than 89%.

Detailed Description

The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.

In the present invention, the carbon-based catalyst refers to a catalyst in which an active component of the catalyst contains carbon element.

The invention provides a method for dehydrogenating alkyl aromatic hydrocarbon, which comprises the following steps: under the condition of no water, the water-soluble organic solvent is used,

(1) carrying out first contact on a raw material containing alkyl aromatic hydrocarbon and a carbon-based catalyst to generate a material flow W;

(2) and carrying out second contact on the material flow W and a ferrum-potassium-cerium catalyst to obtain the alkyl alkenyl arene.

According to the invention, the process can be carried out in a fixed bed reactor. The carbon-based catalyst and the iron-potassium-cerium catalyst can be filled in two fixed bed reactors or the same fixed bed reactor. Preferably, the carbon-based catalyst and the iron potassium cerium catalyst are respectively filled in two fixed bed reactors connected in series, or the carbon-based catalyst and the iron potassium cerium catalyst are filled in different beds of one fixed bed reactor, and the carbon-based catalyst is positioned at the upstream of the iron potassium cerium catalyst along the material flow direction.

According to a preferred embodiment of the present invention, the loading ratio of the carbon-based catalyst to the iron-potassium-cerium-based catalyst is 1: (0.1-1), preferably 1: (0.2-0.4). In the preferred embodiment, the dosage ratio of the dual catalyst system provided by the invention can ensure the smooth proceeding of the alkyl aromatic dehydrogenation reaction, and is more favorable for reducing the production cost of the alkane olefin aromatic.

According to the invention, the optional types of the alkyl aromatic hydrocarbon are wide in range, the substituent on the benzene ring of the alkyl aromatic hydrocarbon can be linear alkyl, branched alkyl aromatic hydrocarbon or cycloalkyl, and the number of the substituent on the benzene ring of the alkyl aromatic hydrocarbon can be one, two, three, four, five or six. Preferably, the number of carbon atoms in the substituent on the benzene ring of the alkylaromatic hydrocarbon is less than 6, further preferably, the alkylaromatic hydrocarbon is selected from at least one of ethylbenzene, methylethylbenzene and diethylbenzene, more preferably ethylbenzene. In the present invention, the reaction is carried out by oxidative dehydrogenation of ethylbenzene, which is merely illustrative of the present invention, and the present invention is not limited thereto.

According to the present invention, preferably, the alkylaromatic-containing feedstock contains alkylaromatic, diluent and oxidant.

According to the invention, the oxidizing agent is an oxygen-containing gas. The oxygen-containing gas in the present invention is selected from a wide range, and may be pure oxygen or a mixed gas of oxygen and other inert gases, and preferably, the oxygen content in the oxidizing agent is 10 vol% or more, preferably 20 vol% or more, more preferably air and/or oxygen, and still more preferably oxygen.

According to the present invention, preferably, the diluent is selected from at least one of inert gases. The inert gas is a gas inert to the oxidative dehydrogenation of ethylbenzene, and is preferably at least one of nitrogen, helium and argon.

According to a preferred embodiment of the invention, the bulk concentration of the alkylaromatic hydrocarbon in the feed is chosen within a wide range, preferably from 0.5 to 15% by volume, and the molar ratio of alkylaromatic hydrocarbon to oxidant, calculated as oxygen, is from 1: (0.1-2), more preferably 1: (0.5-1). By adopting the preferred embodiment, the smooth proceeding of the oxidative dehydrogenation reaction of the alkyl aromatic hydrocarbon can be ensured, and the dosage of the oxidant can be reduced.

According to a preferred embodiment of the present invention, the carbon-based catalyst comprises a carrier and an active component supported on the carrier.

The carrier is selected in a wide range in the invention, as long as the catalyst prepared by loading the active component on the carrier can achieve the purpose of the invention. The carrier may be at least one of molecular sieve, alumina, silica and silicon carbide. According to the invention, preferably, the support is silicon carbide, preferably β -SiC. When the beta-SiC carrier is adopted, the catalyst formed by the active component and the carrier has better selectivity and stability in the process of alkyl aromatic dehydrogenation reaction.

According to the present invention, preferably, the active component is at least one of nanodiamond, nanocellulose, and carbon nanotubes, and is further preferably nanodiamond.

Further preferably, the active component includes nanodiamond and a modifying element selected from at least one of nitrogen, phosphorus, and boron. The preferred embodiment is more beneficial to further improving the activity, selectivity and stability of the catalyst in the process of alkyl aromatic dehydrogenation reaction.

According to the invention, the content of the modifying element in the active component is preferably from 1 to 45% by weight, preferably from 20 to 38% by weight.

According to the invention, the modifying element can be one of boron, nitrogen and phosphorus, or optionally two of the boron, nitrogen and phosphorus, or three of the boron, nitrogen and phosphorus.

According to a preferred embodiment of the present invention, the modifying element is a nitrogen element and/or a phosphorus element, preferably a nitrogen element and a phosphorus element, and further preferably, the mass ratio of the nitrogen element to the phosphorus element is (1-40): 1, preferably (3-33): 1. the carbon-based catalyst adopting the embodiment is used in the oxidative dehydrogenation reaction process of alkyl aromatic hydrocarbon, the activity is better, and the selectivity of the alkyl alkenyl aromatic hydrocarbon product is higher.

According to the present invention, preferably, the carbon-based catalyst has a specific surface area of 70 to 250m²Per g, more preferably 90 to 200m²(ii) in terms of/g. In the present invention, the specific surface area isThe test is carried out by adopting a Tristar 3000 type physical adsorption instrument of Micromeritics company in the United states and using N₂As adsorbates, the samples were subjected to vacuum pretreatment at 300 ℃ and the BET method was used to calculate the specific surface area of the catalyst samples.

According to the present invention, preferably, the particle size of the active component is 1 to 10 nm. In the present invention, the particle size of the active ingredient is measured using a FEI Tecnai G2F 20S-TWIN transmission electron microscope in the United states, unless otherwise specified.

The content of the active component in the carbon-based catalyst is selected in a wide range, and preferably, the content of the active component is 20-60 wt%, preferably 35-50 wt% based on the total amount of the carbon-based catalyst; the content of the carrier is 40 to 80% by weight, preferably 50 to 65% by weight. The adoption of the preferred embodiment is more beneficial to further improving the activity, selectivity and stability of the carbon-based catalyst in the dehydrogenation of the alkyl aromatic hydrocarbon.

The invention can achieve the purpose of the invention as long as the preparation method with the characteristics of the carbon-based catalyst is obtained, the selection range of the preparation method of the carbon-based catalyst is wider, the preparation method can be a conventional method in the field, a specific preparation method of the carbon-based catalyst is provided, and the invention is not limited to the method.

According to the present invention, preferably, the method for preparing the carbon-based catalyst comprises:

(a-1) mixing the nanodiamond, glucose, a dispersing agent, a solvent and an optional compound containing a modification element to obtain an active component suspension;

(a-2) impregnating the carrier in the active component suspension of the step (a-1), and then sequentially performing drying, pre-calcination and calcination.

In the mixing process of the nanodiamond, the compound containing the modifying element, the glucose, the dispersant and the solvent in the step (a-1), the adding sequence of the materials is not particularly limited, and the nanodiamond, the compound containing the modifying element, the glucose, the dispersant and the solvent can be added together, or after mixing two of the components, the other rest components can be sequentially added. In order to enhance the mixing uniformity, glucose and a dispersant can be dissolved in a solvent, then a compound containing a modification element is added, and finally the nano-diamond is added.

In the present invention, the mixing temperature is not particularly limited, and may be, for example, from room temperature to 80 ℃ and, for energy saving and ease of operation, it is preferable that the mixing is carried out at room temperature (20 to 30 ℃).

According to the present invention, preferably, the solvent is water and/or an organic solvent. The water can be distilled water, deionized water or ultrapure water, and is further preferably ultrapure water; the organic solvent is not particularly limited in the present invention, and may be conventionally selected in the art, and examples thereof include alkanes, alcohols, esters, and carboxylic acids, more preferably alcohols, still more preferably methanol and/or ethanol, and particularly preferably ethanol.

According to the present invention, the amount of the solvent is selected from a wide range, and can be determined by those skilled in the art according to the content of the active component in the target catalyst and the water absorption of the carrier.

The invention has wide selection range of the dispersant as long as the aim of dispersing powder can be achieved. Preferably, the dispersant is selected from at least one of citric acid, ammonium citrate and polyethylene glycol, and further preferably citric acid.

According to the present invention, preferably, the mass ratio of the dispersant to the nanodiamond is 0.5 to 2: 1, preferably 1 to 1.5: 1.

according to the invention, preferably, the mass ratio of glucose to nanodiamond is 0.5-1.5: 1, preferably 0.8 to 1.2: 1.

preferably, the modifying element-containing compound is selected from at least one of a nitrogen source, a boron source, and a phosphorus source.

According to the present invention, the nitrogen source may be a nitrogen-containing compound soluble in the solvent or soluble in the solvent by a dispersant and/or glucose, and preferably, the nitrogen source is selected from at least one of ammonium carbonate, ammonium sulfate, urea and aqueous ammonia, and more preferably ammonium carbonate.

According to the invention, the boron source may be a boron-containing compound soluble in the solvent or soluble in the solvent under the action of a dispersant and/or glucose, preferably the boron source is selected from boric acid and/or sodium tetraborate, more preferably boric acid.

According to the present invention, the phosphorus source may be a phosphorus-containing compound that is soluble in the solvent or soluble in the solvent by the action of a dispersant and/or glucose, preferably, the phosphorus source is selected from at least one of monoammonium phosphate, diammonium phosphate, and ammonium phosphate, and more preferably, monoammonium phosphate.

According to the present invention, preferably, the mixing in step (a-1) is performed under ultrasonic conditions for 10 to 200min, preferably 10 to 100min, more preferably 20 to 60 min.

According to the present invention, the impregnation conditions are not particularly limited, and preferably, the impregnation time in the step (a-2) is 12 to 36 hours. The temperature of the impregnation may be room temperature (20-30 ℃).

According to the present invention, preferably, the drying conditions of step (a-2) include: the temperature is 100 ℃ and 150 ℃, and the time is 5-12 hours.

According to the present invention, preferably, the conditions of the pre-calcination of step (a-2) include: under the oxygen-containing atmosphere, the temperature is 350-550 ℃, and preferably 400-500 ℃; the time is 1 to 8 hours, preferably 2 to 6 hours. The oxygen-containing atmosphere may be pure oxygen or may contain an inert gas (non-reactive gas) in addition to oxygen; the oxygen content in the oxygen-containing atmosphere is preferably 10 vol% or more, more preferably 20 vol% or more, and in order to reduce the production cost, it is preferable that the oxygen-containing atmosphere is air.

According to the present invention, preferably, the calcination conditions of step (a-2) include: under the inert atmosphere, the temperature is 600-900 ℃, and preferably 600-800 ℃; the time is 1-12h, preferably 2-8 h. The inert atmosphere is preferably neon and/or argon. The invention is illustrated in part by the example of argon.

The iron potassium cerium-based catalyst of the present invention conforms to the concept conventionally understood by those skilled in the art.

According to the inventionIn a preferred embodiment, the ferrocenium-cerium-based catalyst comprises: fe₂O₃、K₂O、CeO₂、MoO₃And CaO; more preferably, Fe is contained in the total amount of the ferrocssicacid catalyst₂O₃In an amount of 65-76 wt.%, K₂O content of 6-14 wt%, CeO₂In an amount of 14-20 wt%, MoO₃The content of (A) is 0.5-5 wt%, and the content of CaO is 0.2-5 wt%; more preferably, Fe is added based on the total amount of the ferroceranium-based catalyst₂O₃In an amount of 68-74 wt.%, K₂O content of 8-11 wt%, CeO₂In an amount of 14-19 wt%, MoO₃The content of (B) is 1-3 wt%, and the content of CaO is 1-2 wt%.

The object of the present invention can be achieved by any preparation method capable of producing the characteristics of the ferrocenium-cerium-based catalyst, and the present invention is not particularly limited to the preparation method of the ferrocenium-cerium-based catalyst, and a specific preparation method is provided.

Preferably, the preparation method of the iron potassium cerium-based catalyst comprises the following steps:

(b-1) dry-mixing a first portion of a cerium source, an iron source, a potassium source, a molybdenum source, a calcium source, and a pore-forming agent to obtain a catalyst precursor Q;

(b-2) mixing the second part of cerium source, the solvent and the catalyst precursor Q, extruding the obtained mixture, and calcining.

The relative adding amount of the first part cerium source and the second part cerium source is selected in a wide range, and preferably CeO is used₂The first portion of cerium sources comprises 70-95 wt.% of the total amount of cerium sources (i.e., the total amount of cerium sources added in the first and second portions).

In the dry-blending process of the cerium source, the iron source, the potassium source, the molybdenum source, the calcium source and the pore-forming agent in step (b-1), the order of addition of the respective materials is not particularly limited, and all the components may be dry-blended together, or after dry-blending some two components, the other remaining components may be sequentially added. The specific means for the dry blending is not particularly limited, and for example, the dry blending may be carried out using a stirring tank or a kneader, preferably a kneader, and the kneader of the present invention is not particularly limited as long as the purpose of the dry blending can be achieved.

In the present invention, the temperature for the dry blending is not particularly limited, and may be, for example, from room temperature to 80 ℃ and, for energy saving and ease of operation, the mixing is preferably carried out at room temperature (20 to 30 ℃). Preferably, the dry blending time is 0.5 to 3 hours.

The extrusion molding in step (b-2) is not particularly limited in the present invention, and may be performed according to a conventional technique in the art, and the extrusion molding may be performed in a bar extruder.

Preferably, the conditions of the calcination include: roasting at the temperature of 200-380 ℃ for 2-6h, and then roasting at the temperature of 660-950 ℃ for 4-12 h. In this preferred mode, the resulting catalyst has better activity.

In the present invention, there is no particular limitation on the specific selection of the cerium source, the iron source, the potassium source, the molybdenum source, and the calcium source, as long as the corresponding oxides can be produced by subsequent firing.

The cerium source is selected from a wide range, and may be a cerium-containing compound, preferably, the cerium source is selected from at least two of cerium oxalate, cerium nitrate, cerium sulfate, cerium carbonate, cerium hydroxide and cerium acetate, and more preferably, cerium oxalate and cerium nitrate. For example, the cerium source in step (b-1) is cerium oxalate and the cerium source in step (b-2) is cerium nitrate.

The iron source is selected from a wide range, the iron source can be an iron-containing compound, preferably, the iron source is selected from at least one of iron oxide red, iron oxide yellow and iron oxide black, and further preferably, the iron oxide red.

The potassium source is selected from a wide range, and may be a potassium-containing compound, preferably, the potassium source is selected from at least one of potassium carbonate, potassium nitrate, potassium sulfate, potassium oxalate and potassium hydroxide, and more preferably, potassium carbonate.

In the present invention, the molybdenum source is selected from a wide range, and the molybdenum source may be a molybdenum-containing compound, preferably, the molybdenum source is selected from at least one of ammonium molybdate, molybdenum carbonate, molybdenum nitrate, molybdenum sulfate, molybdenum oxalate and molybdenum oxide, and more preferably, ammonium molybdate.

In the present invention, the calcium source is selected from a wide range, and the molybdenum source may be a calcium-containing compound, preferably, the calcium source is selected from at least one of calcium carbonate, calcium nitrate, calcium sulfate, calcium oxalate, calcium hydroxide and calcium oxide, and more preferably, calcium carbonate.

The pore-forming agent of the present invention may be conventionally selected in the art, and preferably, the pore-forming agent is selected from at least one of sodium carboxymethyl cellulose, methyl cellulose, hydroxypropyl cellulose and sesbania powder, and more preferably, sodium carboxymethyl cellulose.

The invention has wide selection range of the dosage of the cerium source, the iron source, the potassium source, the molybdenum source, the calcium source and the pore-forming agent, and preferably, the dosage of the cerium source, the iron source, the potassium source, the molybdenum source, the calcium source and the pore-forming agent is that Fe in the iron-potassium-cerium-based catalyst is ensured based on the total amount of the iron-potassium-cerium-based catalyst₂O₃In an amount of 65 to 76% by weight, preferably 68 to 74% by weight; k₂The content of O is 6 to 14% by weight, preferably 8 to 11% by weight; CeO (CeO)₂In an amount of 14 to 20 wt.%, preferably 14 to 19 wt.%; MoO₃In an amount of 0.5 to 5% by weight, preferably 1 to 3% by weight; the CaO content is 0.2 to 5% by weight, preferably 1 to 2% by weight.

According to the present invention, preferably, the solvent is water.

According to a preferred embodiment of the present invention, the conditions of the first contacting and the second contacting each independently comprise: the reaction temperature is 400-600 ℃, and the space velocity of the raw material containing the alkyl aromatic hydrocarbon is 3000-20000 mL/g.h. The reaction pressure may be normal pressure.

According to a preferred embodiment of the present invention, the conditions of the first contacting and the second contacting each independently comprise: the reaction temperature is 450-550 ℃, and the space velocity of the raw material containing the alkyl aromatic hydrocarbon is 7000-13000 mL/g.h. In the present invention, the space velocity refers to the total space velocity with respect to the total amount of catalyst charged, unless otherwise specified.

The present invention will be described in detail below by way of examples. In the following preparation examples, the particle size of the active component in the carbon-based catalyst was measured using a FEI Tecnai G2F 20S-TWIN transmission electron microscope in the United states; the content of the boron element and the phosphorus element in the active component can be calculated by the feeding ratio.

The specific surface area of the catalyst sample was calculated by the BET method using a Tristar 3000 type physical adsorption apparatus from Micromeritics, USA, under the specific condition that N is used₂As adsorbates, catalyst samples were pretreated by evacuation at 300 ℃.

The raw materials used in the examples and the preparation examples are all commercially available products. Wherein the nano-diamond is commercially available from Reliter science and technology Limited of Beijing, and has a specification of 4-6 nm; beta-SiC is commercially available from Sicat, France.

Preparation examples I-1 to I-6 are illustrative of the preparation of carbon-based catalysts

Preparation example I-1

(1) 0.6894g of glucose and 1.0341g of citric acid were dissolved in 4ml of water at room temperature (25. + -. 1 ℃ C., the same applies hereinafter), and ammonium carbonate equivalent to 0.3013 g of nitrogen was dissolved in the solution after dissolution (a large amount of bubbles were generated); adding ammonium dihydrogen phosphate equivalent to 0.0093 g of phosphorus into the solution, adding 0.6894g of nano diamond powder after forming a uniform and stable solution, and performing ultrasonic treatment for 30min to form a uniform and stable suspension;

(2) soaking 1.35 g of beta-SiC carrier in the suspension, and drying in an oven at 130 ℃ for 12h after adsorption saturation is achieved; then carrying out pre-calcination treatment at 400 ℃ in air atmosphere for 2 h; finally, calcining at 600 ℃ in argon atmosphere for 9h to prepare the required catalyst S-1, wherein the composition and parameters of the catalyst are shown in Table 1.

Preparation example I-2

(1) Dissolving 0.64g of glucose and 0.8g of citric acid in 4ml of water at room temperature under stirring, and dissolving ammonium carbonate equivalent to 0.15 g of nitrogen in the solution after dissolution (a large amount of bubbles are generated in the process); adding ammonium dihydrogen phosphate equivalent to 0.05 g of phosphorus into the solution, adding 0.8g of nano-diamond powder after forming a uniform and stable solution, and performing ultrasonic treatment for 30min to form a uniform and stable suspension;

(2) soaking 1.86 g of beta-SiC carrier in the suspension, and drying in an oven at 130 ℃ for 12h after the beta-SiC carrier is saturated by adsorption; then carrying out pre-calcination treatment at 400 ℃ in air atmosphere for 2 h; finally, calcining at 700 ℃ in argon atmosphere for 5h to prepare the required catalyst S-2, wherein the composition and parameters of the catalyst are shown in Table 1.

Preparation example I-3

(1) Dissolving 0.744g of glucose and 0.682g of citric acid in 4ml of water at room temperature under stirring, and dissolving ammonium carbonate equivalent to 0.3688 g of nitrogen in the solution after dissolution (a large amount of bubbles are generated in the process); adding ammonium dihydrogen phosphate equivalent to 0.0112 g of phosphorus into the solution, adding 0.62g of nano-diamond powder after forming a uniform and stable solution, and performing ultrasonic treatment for 30min to form a uniform and stable suspension;

(2) 1g of beta-SiC carrier is soaked in the suspension, and after the suspension is saturated by adsorption, the suspension is dried in an oven at the temperature of 130 ℃ for 12 hours; then carrying out pre-calcination treatment at 400 ℃ in air atmosphere for 2 h; finally, calcining at 700 ℃ in argon atmosphere for 5h to prepare the required catalyst S-3, wherein the composition and parameters of the catalyst are shown in Table 1.

Preparation example I-4

(1) Dissolving 0.8g of glucose and 0.9g of citric acid in 2ml of water and 2ml of absolute ethanol at room temperature under stirring, and dissolving ammonium carbonate equivalent to 0.2902 g of nitrogen in the solution after dissolution (a large amount of bubbles are generated in the process); adding ammonium dihydrogen phosphate equivalent to 0.0186 g of phosphorus into the solution, adding 0.6912% of nano diamond powder after forming a uniform and stable solution, and performing ultrasonic treatment for 30min to form a uniform and stable suspension;

(2) soaking 0.7 g of beta-SiC carrier in the suspension, and drying in an oven at 130 ℃ for 12h after adsorption saturation is achieved; then carrying out pre-calcination treatment at 400 ℃ in air atmosphere for 2 h; finally, calcining at 700 ℃ in argon atmosphere for 5h to prepare the required catalyst S-4, wherein the composition and parameters of the catalyst are shown in Table 1.

Preparation examples I-5

Following the procedure of preparation I-1, except that no ammonium dihydrogen phosphate was added in step (1), i.e. no phosphorus source was introduced, the specific step (1) included:

(1) dissolving 0.6894g of glucose and 1.0341g of citric acid in 4ml of water at room temperature, stirring and dissolving, dissolving 0.3013 g of nitrogen-containing ammonium carbonate in the solution after the dissolution (a large amount of bubbles are generated in the process), adding 0.6987g of nano diamond powder after a uniform and stable solution is formed, and performing ultrasonic treatment for 30min to form a uniform and stable suspension;

(2) soaking 1.35 g of beta-SiC carrier in the suspension, and drying in an oven at 130 ℃ for 12h after adsorption saturation is achieved; then carrying out 400 ℃ pre-calcination treatment in air atmosphere for 2 h; finally, calcining at 600 ℃ in argon atmosphere for 9h to prepare the required catalyst S-5, wherein the composition and parameters of the catalyst are shown in Table 1.

Preparation example I-6

Following the procedure of preparation I-1, except that ammonium carbonate was not added in step (1), i.e., no nitrogen source was introduced, the specific step (1) included:

(1) dissolving 0.6894g of glucose and 1.0341g of citric acid in 4ml of water at room temperature, stirring and dissolving, adding ammonium dihydrogen phosphate equivalent to 0.0093 g of phosphorus into the solution after the glucose and the citric acid are dissolved, adding 0.9907g of nano diamond powder after a uniform and stable solution is formed, and performing ultrasonic treatment for 30min to form uniform and stable suspension;

(2) soaking 1.35 g of beta-SiC carrier in the suspension, and drying in an oven at 130 ℃ for 12h after adsorption saturation is achieved; then carrying out 400 ℃ pre-calcination treatment in air atmosphere for 2 h; finally, calcining at 600 ℃ in argon atmosphere for 9h to prepare the required catalyst S-6, wherein the composition and parameters of the catalyst are shown in Table 1.

TABLE 1

Note: the content of the modified element is based on the total amount of the active components, and the content of the active components is based on the total amount of the carbon-based monolithic catalyst.

Preparation examples II-1 to II-3 are illustrative of the preparation of the iron potassium cerium-based catalyst.

Preparation example II-1

Will correspond to 68.68 parts of Fe₂O₃Iron oxide red of (1), corresponding to 10.16 parts of K₂Potassium carbonate of O, equivalent to 13.03 parts of CeO₂Corresponding to 1.25 parts of MoO₃Ammonium molybdate (b), calcium carbonate corresponding to 1.29 parts of CaO, and 5.0 parts of sodium carboxymethylcellulose (c) were stirred in a kneader for 1.5 hours to obtain a catalyst precursor Q. Will correspond to 5.59 parts of CeO₂Dissolving cerium nitrate in deionized water accounting for 23.5 percent of the total weight of the catalyst raw materials, adding the dissolved cerium nitrate into a catalyst precursor Q, wet-kneading for 0.6 hour, taking out and extruding into particles with the diameter of 3 mm and the length of 5 mm, putting the particles into an oven, baking for 4.5 hours at 50 ℃, baking for 10 hours at 120 ℃, then baking for 6 hours at 350 ℃, then baking for 5 hours at 850 ℃ to obtain a finished catalyst, crushing the particles into particles with the size of 60-80 meshes, and recording the particles as a catalyst X. The catalyst composition is listed in table 2.

Preparation example II-2

Will correspond to 73.12 parts Fe₂O₃The iron oxide red of (A) is equivalent to 8.52 parts of K₂Potassium carbonate of O, equivalent to 13.06 parts of CeO₂Cerium oxalate, equivalent to 2.03 parts of MoO₃Ammonium molybdate (b), calcium carbonate corresponding to 1.82 parts of CaO, and 5.8 parts of sodium carboxymethylcellulose (c) were stirred in a kneader for 1.3 hours to obtain a catalyst precursor Q. Equivalent to 1.45 parts of CeO₂Dissolving cerium nitrate in deionized water accounting for 23.5 percent of the total weight of the catalyst raw materials, adding the dissolved cerium nitrate into a catalyst precursor Q, wet-kneading for 0.6 hour, taking out and extruding into particles with the diameter of 3 mm and the length of 5 mm, putting the particles into an oven, baking for 4.5 hours at 55 ℃, baking for 10 hours at 120 ℃, then baking for 6 hours at 370 ℃, then baking for 5 hours at 860 ℃ to obtain a finished catalyst, crushing the particles into 60-80 meshes of particles, and recording the particles as catalysisAnd (C) an agent Y. The catalyst composition is listed in table 2.

TABLE 2

Preparation example II-3

The process of preparation II-1 was followed except that the cerium source was added in one portion, specifically:

will correspond to 68.68 parts of Fe₂O₃Iron oxide red of (1), corresponding to 10.16 parts of K₂Potassium carbonate of O, corresponding to 18.62 parts of CeO₂Corresponding to 1.25 parts of MoO₃Ammonium molybdate (b), calcium carbonate corresponding to 1.29 parts of CaO, and 5.0 parts of sodium carboxymethylcellulose (c) were stirred in a kneader for 1.5 hours to obtain a catalyst precursor Q. Mixing the catalyst precursor Q with deionized water accounting for 23.5 percent of the total weight of the catalyst raw materials, wet-kneading for 0.6 hour, taking out and extruding into strips, extruding into particles with the diameter of 3 mm and the length of 5 mm, putting into an oven, baking for 4.5 hours at 50 ℃, baking for 10 hours at 120 ℃, then roasting for 6 hours at 350 ℃, then roasting for 5 hours at 850 ℃ to obtain a finished catalyst, crushing into particles with the size of 60-80 meshes, and recording as the catalyst Z.

Example 1

Reacting reaction gas with a double-catalyst system in an isothermal fixed bed reactor, wherein the upper layer of the fixed bed reactor is filled with a carbon-based catalyst S-1, the lower layer is filled with a ferro-potassium-cerium catalyst X, the total filling amount of the catalysts is 150mg, the reaction temperature is 500 ℃, the reaction pressure is normal pressure, the flow rate of the reaction gas is 30mL/min, the content of ethylbenzene in the reaction gas is 2.9 volume percent, the content of oxygen in the reaction gas is 2.9 volume percent, and the balance is helium. The reaction results are shown in Table 3.

Examples 2 to 7

The procedure of example 1 was followed except that the types of the carbon-based catalyst and the ferrocement-based catalyst and the loading ratio were as shown in Table 3. The reaction results are shown in Table 3.

Example 8

The procedure is as in example 1, except that the reaction temperature is 450 ℃. The reaction results are shown in Table 3.

Example 9

The process of example 1 was followed except that the reaction gas had an ethylbenzene content of 4 vol%, an oxygen content of 2 vol% and the balance helium. The reaction results are shown in Table 3.

Comparative example 1

The procedure of example 1 was followed except that the catalyst was entirely carbon-based catalyst S-1. The results are shown in Table 3.

Comparative example 2

The procedure of example 1 was followed except that the catalyst was entirely a potassium iron cerium-based catalyst X. The reaction results are shown in Table 3.

Comparative example 3

The procedure of example 1 was followed except that in the bed of the reactor, the upper layer was packed with the iron-potassium-cerium-based catalyst X and the lower layer was packed with the carbon-based catalyst S-1.

TABLE 3

In the invention, alkyl arene reacts with a double-catalyst system, the upstream catalyst is a carbon-based catalyst, and the downstream catalyst is a ferrum-potassium-cerium-based catalyst, so that the method for preparing the alkyl alkenyl arene has the characteristics of suitability for long-period operation, high conversion rate of the alkyl arene and high product selectivity.

The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.